Dic08.pdf

AÑO 2, NÚMERO 16, DICIEMBRE DE 2008
Los progestágenos
Los progestágenos son un grupo de hormonas esteroides y como todas las hormonas
esteroides derivan del colesterol, son liposolubles, no se degradan en el aparato digestivo
y son absorbibles a través de la piel y de las mucosas. La progesterona es el
progestágeno natural y los hay sintéticos como el norgestomet, acetato de fluorogestona
(FGA), altrenosgest y acetato de melengestrol (MGA). Los progestágenos disminuyen la
secreción de la hormona liberadora de gonadotropinas (GnRH) en el hipotálamo así como la respuesta
de la hipófisis a la GnRH; de esta forma, inhiben la maduración folicular y la ovulación. Por sus efectos,
se han utilizado con éxito como anticonceptivos en humanos y para el control artificial de la
reproducción en los animales domésticos. En los bovinos se utilizan para la sincronización del estro y en
hembras en anestro para la inducción de actividad ovárica. Las presentaciones comerciales más
comunes son los implantes auriculares que contienen norgestomet y los dispositivos intravaginales que
liberan progesterona; ambas eficaces y de fácil manejo en el campo. El MGA es un progestágeno oral
que se utiliza en hembras mantenidas en corrales de engorda para suprimir el estro y la ovulación. El
MGA se puede mezclar fácilmente con cualquier concentrado o grano molido y la dosis utilizada por vaca
es de 0.5 mg al día, en tratamientos de 9 a 14 días. Después del último día de tratamiento, el estro
ocurre entre los días 2 y 7. El periodo que transcurre entre el retiro del MGA hasta el estro es más largo
si se compara con otros progestágenos. Esto obedece al tiempo de eliminación del MGA, ya que
mientras un implante o un dispositivo intravaginal se retiran en forma abrupta, el MGA continua
absorbiéndose durante su paso por el tracto gastrointestinal. En tratamientos de 14 días se pueden
obtener porcentajes de concepción menores que en el estro natural, lo cual se debe en gran medida a la
ovulación de folículos persistentes. Así, un tratamiento eficaz consiste en la administración de MGA
durante 14 días, seguido de una inyección de PGF2α 15 o 17 días después del retiro del progestágeno,
con lo cual, una alta proporción de hembras tendrá un cuerpo lúteo al momento de la inyección de la
PGF2α. O bien, otro esquema práctico y con buenos resultados es la administración de MGA durante 9
días, más una dosis de PGF2α en el día 9. Este último, lo hemos evaluado en vaquillas Holstein y el
porcentaje de hembras sincronizadas resulta alto (95%) con una tasa de preñez de hasta el 70%. Como
puede observarse, los resultados con MGA son comparables con otros esquemas comerciales de
sincronización y a menor costo. NR
Dr. Joel Hernández Cerón y M.C. Álvaro Ortega León
Compiladores
Departamento de Reproducción
1
Noticias de Reproducción Bovina
DICIEMBRE 2008
Nota técnica
¿QUÉ SON LOS ANIMALES TRANSGÉNICOS?
Yvonne C. Ducolomb Ramírez1, Salvador Romo García2.
1
Universidad Autónoma Metropolitana–Iztapalapa. 2FES - Cuautitlán.
UNAM.
INTRODUCCION
La transgénesis es una técnica que está tomando
gran importancia en la modificación genética de
todo tipo de animales. Las modificaciones que
podrían realizarse involucrarían cambios para que
los
animales
domésticos
aumenten
su
productividad, la cantidad y calidad de la carne y
la leche, y la resistencia a enfermedades. En el
campo de la biomedicina, a través de los animales
transgénicos, se están obteniendo productos
farmacéuticos y órganos para xenotransplantes
para el tratamiento de ciertos padecimientos.
La transgénesis es la modificación genética de un
organismo mediante la introducción de ADN
exógeno que contiene genes específicos, a células
embrionarias totipotenciales. Estas células pueden
ser ovocitos fertilizados, células embrionarias en
un estado temprano de desarrollo o células madre
(también llamadas células troncales o células de
tallo embrionario), que pueden proceder de la
masa celular interna de un embrión en etapa de
blastocisto. La integración del ADN a los
cromosomas puede deberse a que la célula lo
reconoce como un fragmento roto que debe de
ser reparado.
Si el ADN exógeno se integra a los cromosomas
del ovocito fertilizado, el animal será totalmente
transgénico ya que todas sus células tendrán el
gen ajeno, llamado transgen. Cuando la
integración ocurre en el estado posterior a la
formación del cigoto, algunas de sus células
incorporarán el transgen, a estos animales se les
llama mosaicos. Si el transgen se integra en la
línea germinal a partir de la cual se forman los
espermatozoides o los ovocitos, la modificación
genética pasará a toda la descendencia.
El objetivo de la transgénesis es producir animales
fundadores
capaces
de
transmitir
las
características deseadas a su descendencia y de
esa manera mejorar la calidad de vida del hombre
y de los animales.
La transgénesis se ha extendido a diversas
especies domésticas como conejos, borregos,
cerdos y bovinos. En la producción animal provee
un mecanismo mediante el cual se pueden
obtener características deseadas en los animales
de una manera más rápida que por medio de la
selección a partir de la crianza selectiva, sin el
inconveniente de la propagación de características
genéticas asociadas que posiblemente no son
deseables.
En los últimos 15 años se han realizado avances
considerables en la producción de animales
genéticamente
modificados.
Los
animales
domésticos
transgénicos
constituyen
una
herramienta muy útil para evaluar la función de
un gen determinado. A la fecha, los
investigadores
han
empleado
animales
transgénicos para determinar la importancia de
genes involucrados en el crecimiento, desarrollo,
resistencia a las enfermedades infecciosas o
parasitarias,
terapias
humanas,
eficiencia
alimenticia, respuesta inmunológica y lactancia.
Además, han sido identificados genes específicos
que le confieren a la leche características
nutritivas y la posibilidad de producir proteínas
biofarmacéuticas.
Los
animales
lecheros
modificados genéticamente pueden proporcionar
productos lácteos de mayor valor económico.
La manipulación transgénica del ganado puede
minimizar el empleo de antibióticos, pesticidas y
puede ser de utilidad en la producción pecuaria.
Además de la posibilidad de controlar
enfermedades,
puede
colaborar
en
la
preservación de la diversidad genética. La
importancia del ganado transgénico aparte de la
producción animal, tiene un papel muy importante
en la producción biofarmacéutica.
TÉCNICAS PARA PRODUCIR ANIMALES TRANSGÉNICOS
Algunas de las metodologías que se utilizan para
la transferencia de genes en distintos tipos
celulares
son:
microinyección
de
ADN,
transferencia nuclear o clonación, transferencia
genética retroviral, transgénesis por medio de
espermatozoides y transgénesis por medio de
células madre o troncales.
COMO PUEDE UTILIZARSE LA TRANSGÉNESIS
Históricamente el ganado ha sido seleccionado
con base en sus características y no por los genes
deseables. Muchos rasgos fenotípicos son
dependientes de la interacción de múltiples genes
2
Noticias de Reproducción Bovina
a lo largo del tiempo, por lo que éstos no se
prestan a modificaciones fácilmente. Antes de que
la transgénesis se realice, se debe evaluar el
impacto de las intervenciones genéticas sobre el
ganado tanto en aspectos biológicos como de
mercado.
En la selección de las características a modificarse
es fundamental que la genómica funcional se
encuentre
claramente
comprendida.
Es
importante poder relacionar el gen con la función
de la proteína a la cual codifica antes de intentar
manipularlo en el animal.
En los animales domésticos, las características
introducidas pueden ser clasificadas en diferentes
categorías: a) Las que puedan tener un beneficio
para el productor mediante la reducción de los
costos asociados con la producción. b) Las que
agreguen cierto valor a un producto alimenticio.
c) Las que puedan proveer nuevos productos de
consumo de tipo alimenticio y/o de tipo
farmacéutico. d) Las que reduzcan los gastos en
el manejo y los problemas en las instalaciones
relacionados con los animales. e) Las que
diversifiquen los productos de origen animal
produciendo nuevas oportunidades económicas en
las áreas rurales, y f) Las que puedan conferir al
animal resistencia a las enfermedades y por lo
tanto contribuyan a reducir el uso de antibióticos,
medicamentos y gastos veterinarios.
EJEMPLOS DE CAMBIOS EN LA PRODUCTIVIDAD
Una de las metas de la producción animal es
mantener y aumentar la producción de alimentos
sin deterioro del medio ambiente. En la
porcicultura, la contaminación por fósforo
proveniente del excremento de cerdo y otros
animales monogástricos es un gran problema.
Este abono, rico en fósforo, es el resultado de la
incapacidad de estos animales para digerir el
fitato de fósforo que es común en los granos de
los cereales y semillas oleaginosas, y en los
suplementos alimenticios con fosfatos minerales
que se emplean para que los animales alcancen
un desarrollo óptimo. Además, estos fertilizantes
orgánicos llegan a los ríos provenientes de
grandes explotaciones, alterando las cadenas
alimenticias y causando la muerte de peces y
animales acuáticos.
Se han empleado diversas estrategias para tratar
de reducir o eliminar el fósforo mineral de la dieta
de los porcinos, una de éstas es emplear como
DICIEMBRE 2008
alimento harina de carne o de hueso. Sin
embargo, esto ha conducido a la propagación de
enfermedades entre los animales. Otra estrategia
es la de complementar el alimento con fitasa, que
es una enzima que libera el fósforo del fitato.
Recientemente, se han producido cerdos
transgénicos que producen la enzima fitasa en la
saliva, lo que les permite digerir el fósforo del
fitato. Estos cerdos casi no requieren suplementos
de fosfatos inorgánicos para alcanzar una buena
talla y excretan 75% menos fósforo en las heces
que los cerdos no transgénicos.
Se han producido borregas transgénicas en las
que se ha aumentado la producción de lana.
También se han producido vacas genéticamente
modificadas que pueden producir en su leche
diversos productos con gran valor económico. En
este caso, la transgénesis se emplea para
modificar la composición de los productos con
varios propósitos, por ejemplo la composición de
la leche para que sea confiable y de alto valor
nutritivo. Esta selección puede ocurrir mediante la
modificación de las proteínas ya presentes o
mediante la adición de nuevas proteínas. También
puede haber modificaciones relacionadas con la
congelación, el sabor y la alergenicidad. Algunas
vacas tienen ciertas características en las
proteínas de su leche que son poco favorables
para la elaboración de quesos, la leche con más
cantidad de kappa caseína es más adecuada para
la elaboración de quesos. Algunas de estas
características son adecuadas pero se presentan
con poca frecuencia en la población. La tecnología
transgénica puede usarse para insertar ADN,
favoreciendo la expresión de dichas características
en las razas que no los presentan, preservando
así la diversidad genética.
Los transgenes seleccionados, deben de ser
socialmente aceptados. La producción de
alimentos transgénicos para la población humana
genera controversia porque la opinión que se
tiene de este recurso como una medida para
incrementar los recursos alimenticios es diferente
de la aceptación que se tiene de los productos
biofarmacéuticos producidos por transgénesis.
EJEMPLOS DE AUMENTO EN EL CRECIMIENTO Y
DESARROLLO
La mayoría de los estudios de transferencia de
genes principalmente en ovinos y porcinos, se han
realizado con genes que regulan el crecimiento.
Algunos cerdos transgénicos que expresan el gen
3
Noticias de Reproducción Bovina
DICIEMBRE 2008
promotor de la hormona de crecimiento bovino
ganan peso más rápidamente y aumentan su
eficiencia alimenticia. La expresión de algunos
genes produce una reducción en la grasa del
lomo, la cual es una característica deseable desde
el punto de vista productivo. Sin embargo, la
mayoría de los cerdos han mostrado una
sobreexpresión de la hormona de crecimiento, la
cual ha sido asociada con diversos efectos
secundarios negativos, como la disminución del
apetito, letargo, artritis, descenso en la fertilidad y
alta incidencia de úlceras pépticas.
leche para el consumo, sean capaces de producir
en la glándula mamaria proteínas con
características farmacéuticas que puedan ser
empleadas en el tratamiento de enfermedades en
el humano.
Los genes que codifican para la β-lactoglobulina
en los ovinos hacen que la expresión de esta
proteína en la glándula mamaria sea más eficiente
y específica. Se ha construido una fusión de esta
secuencia de genes, con la secuencia que codifica
para el factor IX antihemofílico humano, dando
como resultado su producción en la leche ovina.
Se ha demostrado también, que una modificación
de la hormona porcina del crecimiento ha tenido
efectos benéficos sobre importantes parámetros
del crecimiento sin efectos colaterales negativos,
por lo que estas líneas de cerdos transgénicos
podrían ser una opción para la alimentación
humana.
También la glándula mamaria del porcino puede
ser usada para producir proteínas recombinantes
de uso farmacéutico. Se ha logrado la producción
de cerdas transgénicas que tienen el gen para
producir la proteína C humana en la leche. En
humanos, la ausencia congénita de esta proteína
conduce a una coagulación intravascular no
controlada y a la muerte. Si este padecimiento se
diagnostica a tiempo y se suministra la proteína C
que es requerida como un anticoagulante a
pacientes con esta deficiencia, la enfermedad
desaparece.
EJEMPLOS DE MODELOS PARA EL ESTUDIO DE
ENFERMEDADES HUMANAS
La producción de ganado transgénico creará un
nuevo campo en la producción animal que tendrá
por objeto obtener productos farmacéuticos a
partir de animales, que sean aplicables en
medicina humana.
En ovinos y porcinos se han introducido genes
para
incrementar
la
resistencia
a
las
enfermedades y así poder producir moléculas
inmunológicamente relacionadas con dicha
resistencia. Otra área en la que los animales
transgénicos, especialmente los cerdos, tendrá un
gran impacto, será en el desarrollo de modelos de
enfermedades genéticas humanas.
Hasta ahora los ratones han sido el principal
modelo, aunque no el más adecuado para
estudiar enfermedades como la arteriosclerosis,
anemia falciforme, enfermedad de Alzheimer,
enfermedades autoinmunes, linfáticas, dermatitis
y cáncer de próstata. Muchos de estos modelos
tendrán que ser llevados a cabo en animales
domésticos para poder ser útiles para el humano.
El cerdo podría ser un modelo apropiado para
solucionar una afección humana conocida como
retinitis pigmentosa, debido a la similitud y al
tamaño del ojo entre el hombre y el porcino.
EJEMPLOS DE PRODUCCIÓN DE PROTEÍNAS
RECOMBINANTES EN LA LECHE
A nivel mundial se intenta la producción de vacas
y borregas transgénicas que además de producir
La hemofilia A, causada por la deficiencia del
factor VIII de coagulación en la sangre se
presenta con cierta frecuencia en la población. La
enfermedad ha sido tratada con preparados que
contienen dicho factor, pero en ocasiones esto ha
conducido a la transmisión del virus de la
inmunodeficiencia humana (VIH). Por medio de la
tecnología de proteínas recombinantes se ha
podido producir este factor en la leche porcina,
llegándose a obtener hasta 50 mg de proteína por
litro.
EJEMPLOS DE PRODUCCIÓN DE PROTEÍNAS
RECOMBINANTES EN PORCINOS
Recientemente
se
ha
logrado
obtener
hemoglobina humana funcional en cerdos
transgénicos. Mediante la microinyección del gen
de la globina β humana en cigotos porcinos y la
transferencia de estos a hembras receptoras, se
logró que 2.6% de los lechones vivos fueran
transgénicos. Todos expresaron el gen de la
hemoglobina humana que pudo ser purificado
hasta el 99%, exhibiendo una afinidad hacia el
oxígeno similar a la hemoglobina que produce el
humano. La producción de este sustituto de
sangre en animales domésticos tiene la ventaja de
que no presenta patógenos humanos como el
VIH, hepatitis u otros virus.
4
Noticias de Reproducción Bovina
EJEMPLO DE PRODUCCIÓN DE ÓRGANOS PARA
XENOTRANSPLANTES
Los avances en las tecnologías transgénicas
podrán permitir que en unos años, se puedan
producir cerdos modificados genéticamente que
sirvan como donadores de órganos para ser
trasplantados a los humanos. Estos órganos
podrían ser de uso temporal, hasta que se
obtenga un órgano humano apropiado, sin
embargo, la tendencia futura de esta tecnología
es el desarrollo de animales que produzcan
órganos transgénicos que puedan emplearse en
transplantes permanentes.
El cerdo presenta ventajas porque tiene una gran
semejanza en cuanto a sus características
anatómicas, fisiológicas y bioquímicas con el
humano, además, producen un mayor número de
crías que otros animales domésticos y son una
especie en la que es fácil la crianza y
manutención.
Actualmente el mayor impedimento para el
empleo de órganos provenientes de cerdo es el
rechazo
hiperagudo
causado
por
la
incompatibilidad inmunológica que está mediada
por anticuerpos específicos hacia antígenos
presentes en la superficie de las células
endoteliales, pero estos antígenos podrían ser
completamente eliminados mediante transgénesis.
Otra solución sería la creación de cerdos
modificados genéticamente para que produzcan
proteínas inhibidoras del complemento presente
en la sangre. Éste se activa al reconocer algún
elemento que no es propio del organismo y forma
parte de la respuesta del rechazo agudo hacia los
transplantes. Para la obtención de cerdos
adecuados para xenotransplantes se requieren
varios transgenes para producir un donador
adecuado.
Se ha logrado la producción de cerdos
transgénicos que tienen el gen del “factor humano
de aceleración del decaimiento (human decayaccelerating factor), que ayuda a superar el
rechazo hiperagudo de un órgano porcino cuando
es transplantado a un primate no humano,
observando que el 80% de los animales
integraron el gen y esta característica fue
transmitida a su descendencia.
EJEMPLO DE LA RESISTENCIA A ENFERMEDADES
Los animales modificados genéticamente pueden
ser una propuesta interesante para aumentar la
resistencia a ciertas enfermedades. Se pueden
DICIEMBRE 2008
transferir genes de resistencia que produzcan ARN
contra virus, que codifiquen para anticuerpos
monoclonales específicos, que expresen linfocinas
o receptores de linfocitos T.
La resistencia a enfermedades en los animales
domésticos
ofrece
muchas
ventajas:
los
consumidores se benefician porque la producción
de animales sanos contribuye a la obtención de
productos alimenticios sanos, a disminuir el uso
de antibióticos en las granjas y el riesgo de
residuos en los productos alimenticios. Además,
se incrementa el bienestar de los animales
mediante el control de las enfermedades. En
algunos casos, la logística de la aplicación de
vacunas reduce su eficacia, por ejemplo cuando
no se cuenta con los medios adecuados para su
refrigeración ni con las instalaciones necesarias
para la manipulación de dichas vacunas.
En cerdos se realizaron intentos para aumentar la
resistencia hacia la influenza A por microinyección
de genes de ratón, pero su expresión durante la
embriogénesis temprana fue perjudicial para el
desarrollo subsecuente. Por otro lado, no quedó
claro si la expresión transgénica de la proteína
incrementa la resistencia natural contra el virus de
la influenza. La producción de cerdos transgénicos
resistentes a ciertas enfermedades específicas
requiere más estudios a fin de superar los
obstáculos que se han presentado, pero no deja
de ser importante considerar los grandes
beneficios que se obtendrían si se logran éxitos
con estas investigaciones. Otro caso es la
cisticercosis, un problema de salud pública en
México, que afecta al hombre y al cerdo. En este
último, que es el hospedero intermediario podría
ser disminuida su susceptibilidad a esta
parasitosis por medio de la producción de cerdos
transgénicos resistentes. Se ha utilizado un
modelo experimental de cisticercosis en diferentes
cepas de ratones, encontrando que el gen Q9
perteneciente
al
Complejo
Principal
de
Histocompatibilidad está asociado con la
resistencia a esta forma de cisticercosis. Con este
gen, se creó el primer ratón transgénico y se
confirmó la relevancia del gen Q9 en el control de
la parasitosis. Pronto podrían producirse cerdos
transgénicos resistentes a la cisticercosis
CONSIDERACIONES ÉTICAS
A pesar de que la transgénesis parece ofrecer un
mejoramiento de la salud, tanto humana como
animal, y de la producción tanto vegetal como
5
Noticias de Reproducción Bovina
animal, existen dudas y aspectos éticos que
pueden detener su aplicación. La manipulación del
material genético tiene implicaciones sociales,
éticas y religiosas. Algunos grupos no están de
acuerdo con la manipulación de gametos y
embriones. Esto se debe a la preocupación de que
las manipulaciones genéticas puedan afectar la
salud humana y animal, así como dañar al
ambiente. Además, a otros grupos les preocupa
que se lleguen a aplicar en el ser humano.
Hay grupos religiosos, étnicos o culturales que
recomiendan normas alimenticias en las cuales
ciertos animales están prohibidos y estas normas
o tradiciones religiosas pueden ser violadas si los
animales o productos derivados de éstos son el
resultado de la ingeniería genética, afectando la
aceptación de algunos productos alimenticios.
DICIEMBRE 2008
CONCLUSIONES
Los animales transgénicos constituyen un recurso
importante que permite ampliar el conocimiento
sobre el material genético, su función e
interacción en especies domésticas. En muchos
casos este conocimiento puede ser extrapolado al
ser humano, además permite relacionar el
genoma con ciertos estados fisiológicos y
patológicos.
Los
animales
transgénicos
constituyen una herramienta para incrementar la
producción animal, mejorando la calidad de los
alimentos y permitiendo la creación de nuevos
productos alimenticios. Sin embargo, la función de
un transgen en un animal específico, debe de ser
valorada, además de evaluar su impacto sobre la
población y el ambiente.
En algunos países se están desarrollando políticas
para indicar a los consumidores, mediante una
etiqueta, cuales son los alimentos derivados de
animales producidos por ingeniería genética. Las
mismas especificaciones deben hacerse cuando se
trata de productos terapéuticos derivados de
biotecnologías. Pero en contraste, el público tiene
una opinión menos estricta de los productos
obtenidos para usos biomédicos y farmacéuticos
que de los producidos para la alimentación.
La transgénesis puede mejorar la producción
animal por medio de la selección de
características de una manera más rápida y
eficiente que cuando se llevan a cabo
cruzamientos dirigidos entre individuos con
características específicas. En estas últimas, las
modificaciones genéticas que pueden alcanzarse
son más lentas y sólo se pueden obtener las
características deseadas de manera aleatoria, con
el riesgo de presentarse acompañadas con rasgos
que puedan ser inadecuados o perjudiciales a la
producción o a la salud del animal.
Otro aspecto que causa polémica es el bienestar
animal, hay grupos defensores de los animales
que no aprueban la experimentación realizada en
animales. Consideran injusto el sufrimiento y las
consecuencias producto de las manipulaciones
genéticas. Además, piensan que las tecnologías
genéticas violan los derechos y la dignidad de los
animales, independientemente de que sean de
utilidad para el ser humano.
En área de la salud, pueden servir como modelo
para conocer más a fondo las enfermedades
genéticas que afectan al humano y a los animales
de utilidad económica. Constituyen una fuente de
productos biofarmacéuticos útiles en medicina
humana y veterinaria. Además representan un
medio importante para la obtención de órganos
para la realización de xenotransplantes que
pueden mejorar la calidad de la vida humana.
[email protected]
6
Noticias de Reproducción Bovina
DICIEMBRE 2008
Manejo Reproductivo
J. Dairy Sci. 91:4640–4650, 2008
Progesterone, Follicular, and Estrual Responses to
Progesterone-Based Estrus and Ovulation
Synchronization Protocols at Five Stages of the Estrous
Cycle
J. S. Stevenson.
The objective was to monitor changes in ovarian
status in heifers exposed to a progesterone insert
with or without concurrent GnRH injection. Estrus
was manipulated in 283 heifers (31 breeding
clusters) by administering GnRH, progesterone,
and PGF2α at 5 stages of the estrous cycle. Estrus
was presynchronized with a progesterone insert
(CIDR) for 7 d before PGF2α was administered 24
h before insert removal. Successive clusters of
heifers were assigned to treatments (2 heifers per
treatment) on cycle d 2, 5, 10, 15, and 18.
Treatments consisted of a progesterone insert (d
0) for 7 d plus: 1) PGF2 α on d 6, 24 h before
insert removal (early PGF); 2) GnRH on d 0 +
early PGF2α (GnRH + early PGF); 3) PGF2α at
insert removal (late PGF); and 4) GnRH on d 0 +
late PGF (GnRH + late PGF). Controls received
GnRH on d 0 and PGF2α on d 7. Ovaries were
scanned by transrectal ultrasonography on d 0, 2,
7, 9, and 11 to assess follicle diameters and
ovulation. Blood was collected on d 0, 2, 6, 7, 8,
and 9 to quantify serum concentrations of
progesterone.
Insemination
occurred
after
detected estrus or by timed artificial insemination
(TAI) at 64 h after insert removal. Only 25% of
141 GnRH-treated heifers ovulated by d 2; twice
as many ovulated when treatment was initiated
on d 5 (46.4%) than on other cycle days (20.3%).
Diameters of the largest follicle exposed to GnRH
on d 0, 2, 7, or 9 did not differ regardless of
whether ovulation occurred. Small treatment and
stage of cycle differences in diameter of the
largest follicle were detected on d 2, 7, and 9.
Compared
with
controls,
progesterone
concentration was greater in all progesteronetreated heifers on d 2 and 6. Early- vs. late-PGF
treatment resulted in less progesterone on d 7
and 8. Pregnancies per AI were less after TAI
(44%) than after detected estrus (56%) and were
less in controls than in all progesterone
treatments. Heifers in which treatments were
initiated on d 10 of the cycle had the most
consistent (estrus vs. TAI) pregnancies per AI
(65.4%) compared with other cycle days.
Compared with controls, more progesterone
treated heifers ovulated by 96 h after insert
removal. Application of the progesterone insert
reduced variance of the interval to estrus after
insert removal (or PGF2α injection in controls) by
1.6-fold compared with controls. These results do
not support the use of GnRH in a progesteronebased synchronization protocol.
[email protected]
J. Dairy Sci. 91:4552–4559, 2008
Lameness, Activity Time-Budgets, and Estrus
Expression in Dairy Cattle
S. L. Walker, R. F. Smith, J. E. Routly, D. N. Jones, M. J.
Morris, and H. Dobson
Department of Veterinary Clinical Science, Faculty of Veterinary
Science, University of Liverpool, Leahurst, Neston, Wirral CH64 7TE,
United Kingdom.
The aim of the present study was to identify
specific behavioral patterns that contribute to
diminished estrus expression in lame cows.
Behavioral scan and focal sampling were used to
examine the effect of lameness on daily activity
budgets, sexual behavior, feeding activities, and
body condition score. A total of 59 milking cows
(51.8 ± 1.4 d postpartum) were monitored on a
commercial dairy farm for 5 d following estrus
synchronization. Overall, lame cows (n = 39)
spent proportionately less time elevated on their
feet and more time lying down compared with
nonlame cows (n = 20). This included lame cows
spending less time walking or standing. Overall,
the total proportion of scans in which an estrous
behavior was observed was very small but tended
to be smaller for lame compared with nonlame
cows. Throughout a day, lame cows displayed a
lower proportion of estrous behaviors in the early
morning. Lameness did not affect durations of
drinking, grazing, or ruminating, or how these
behavioral states fluctuated throughout the day.
Similarly, rumination chewing rates were the same
for lame and nonlame cows, and there was no
association
between
lameness
and
dominance/displacement while feeding at a feedfence. Lame cows did, however, have a slower
bite rate at pasture and had a lower body
condition score. Lame cows were also nearer the
rear of the herd, both as they left the field and
7
Noticias de Reproducción Bovina
when entering the milking parlor. In conclusion,
lame cows have longer lying times and spend less
time standing, walking, and expressing an estrous
behavior. Lame cows also have a lower bite rate
at pasture and are more likely to be of lower body
condition score.
[email protected]
Animal Reproduction Science 109 (2008) 17–26
Evaluation of vaginal electrical resistance as an
indicator of follicular maturity and suitability for timed
artificial insemination in beef cows subjected to a
synchronization of ovulation protocol
J.F. Zuluagaa,b, J.P. Saldarriagaa,b, D.A. Coopera,b, J.A.
Cartmilla,b, G.L. Williamsa,b
a
Animal Reproduction Laboratory, Texas A&M University Agricultural
Research Station, Beeville, TX 78102, USA. bCenter for Animal
Biotechnology and Genomics, Department of Animal Science, Texas
A&M University, College Station, TX 77843, USA.
Objectives were to test the hypothesis that
vaginal electrical resistance (VER) could be used
to identify cows without a large (<10 mm) follicle
at timed-AI (TAI) following a synchronization of
ovulation protocol and thus serve as a prospective
decision aid for determining cows that should not
be inseminated. Brahman x Hereford (F1) females
(n = 233) were synchronized with the CO-Synch
+ CIDR protocol that consisted of a controlled
internal drug release (CIDR) insert and i.m.
injection of GnRH (GnRH-1; 100 µg) on day 0,
removal of CIDR and i.m. injection of
prostaglandin F2α (PGF; 25 mg) on day 7, and
i.m. injection of GnRH (GnRH-2, 100 µg) and TAI
66 h after CIDR removal (day 10). Vaginal
electrical resistance was determined with a
commercially available device (Ovascan; Animark
Inc., Aurora, CO) at days 0, 7, and 10. Transrectal
ultrasonography was used on day 10 to assess
ovarian morphology at TAI in all cattle and in a
subset of females (n = 98) on days 0 and 7. Mean
(±S.E.M.) age, body condition score (BCS), BW
and days postpartum were 7.2±0.3 years,
5.2±0.1, 538±5.3 kg, and 77±1.1 days,
respectively. Mean VER (Ω) was greatest
(101.4±0.8) on day 0 and declined (P < 0.01) to
95.2±0.8 and 82.0±0.8Ω, respectively, on days 7
and 10. Mean diameter of the largest follicle and
VER values in females conceiving after TAI
differed (P = 0.05) from those that did not
conceive. Mean VER on days 7 and 10 and VER
difference (VER on day 10 minus VER on day 7)
did not differ between females with a small (<10
DICIEMBRE 2008
mm) or large (≥10 mm) follicle at TAI. Timed-AI
pregnancy rate was greater (P < 0.01) for
females with large follicles (43%) than those with
small follicles (22%). Vaginal electrical resistance
difference values, categorized as negative (<0Ω)
or neutral/positive (≥0Ω), did not differ between
females that conceived to TAI compared with
those that did not. We conclude that VER
measurements, as used in the present study, are
not adequately sensitive to differentiate between
females with and without a large follicle and thus
are unable to serve as a prospective decision aid
for determining suitability for TAI after
synchronization.
Veterinary Clinics of North America: Food Animal Practice
Volume 24, Issue 3, Pages 443-453 (November 2008)
Development of Teaser Bulls Under Field Conditions
Gregor L. Morgan, BVSc, MS, PhDa , Lionel J. Dawson, BVSc,
MSab
a
Center for Veterinary Health Sciences, Oklahoma State University, 1BVMTH, Room 002, Stillwater, OK 74078, USA. bAmerican Institute
for Goat Research, Langston University, Langston, OK 73050, USA.
A teaser bull is a term describing a bull whose
reproductive system has been surgically altered to
render him sterile. The purpose of such bulls is to
aid in detection of cows in estrus to facilitate
when to artificially inseminate. The bull is
sterilized by either vasectomy or caudal
epididymectomy. In addition to sterilization, other
surgical options are described that prevent
intromission and the spread of venereal disease.
This article describes briefly some of those
options. The procedures described are those
preferred by the authors and can be performed in
the field. Some of the pros and cons of these
procedures are discussed.
[email protected]
Theriogenology 70 (2008) 1507–1515
The economic effects of an estrus synchronization
protocol using prostaglandin in beef heifers
D.E. Holm, P.N. Thompson, P.C. Irons
Department of Production Animal Studies, Faculty of Veterinary
Science, University of Pretoria, Private Bag X04, Onderstepoort 0110,
South Africa.
We estimated the effect of estrus synchronization
on reproduction, production and economic
outcomes in 272 beef heifers randomly allocated
to a synchronized Test group or an
unsynchronized Control group. The Test group
received AI upon estrus detection for 6 days
followed by PGF2 treatment of heifers that had
not shown estrus by day 6 (PGF/6). In both
8
Noticias de Reproducción Bovina
groups AI was continued for 50 days, followed by
a 42-day bull breeding period. Heifers were
followed through their second breeding season
and until they had weaned their first calves.
Synchronization resulted in a reduction in median
days to first insemination (8 vs. 11 in the Test and
Control groups, respectively, P < 0.01) and
median days to calving of calves born to AI (14
vs. 20, P = 0.04). There was no significant
difference in pregnancy rate to the AI period
(60.0% vs. 51.8%, P = 0.18), final pregnancy
rate (82.2% vs. 83.2%, P = 0.87) or pregnancy
rate to the subsequent breeding season (96.0%
vs. 95.0%, P = 1.00). Although mean calf
weaning mass was not significantly different
(207.0 kg vs. 201.4 kg, P = 0.32), the total mass
of calves weaned in this study was 14,843 kg vs.
13,060 kg and the benefit: cost ratio for
synchronization was 2.8. It was therefore
concluded that a PGF/6 protocol may affect the
total mass of calves weaned by changing days to
calving, weaning rate, the ratio of male: female
calves born and/or the birth mass of calves.
[email protected]
Reprod Dom Anim 43, 735–743 (2008)
A Study of Endometritis Causing Repeat Breeding of
Cycling Iraqi Buffalo Cows
OI Azawi1, SN Omran2 and JJ Hadad3
Department of Surgery and Obstetrics, College of Veterinary
Medicine, University of Mosul, Mosul; 2Department of
Theriogenology, College of Veterinary Medicine, University of
Baghdad, Baghdad; 3Department of Microbiology, College of
Veterinary Medicine, University of Dohuk, Dohuk, Iraq.
1
The objectives of this study were to determine the
non-specific aerobic and anaerobic bacterial
causes of endometritis causing repeat breeding of
cycling Iraqi buffalo cows at Nineveh province,
validate diagnostic criteria for endometritis and to
evaluate the treatment efficiency of using
systemic or intrauterine infusion of antibiotics for
the treatment of endometritis. Data were
collected from 60 buffalo cows with history of
repeat breeding in different herds. All buffaloes
were subjected to detailed clinical examination
including external inspection, vaginoscopy and
transrectal palpation of the cervix, uterus and
ovaries. Swabs for bacteriology and biopsies for
histopathology were collected from the uterine
lumen from each cow. Character, odour and
estimation of polymorphonuclear cells (PMN) of
the vaginal mucus were scored. Blood samples
were collected from cows for creatine kinase (CK)
DICIEMBRE 2008
and
aspartate
aminotransferase
(AST)
measurement.
Treatment
conducted
using
oxytetracycline with tylosin in local intrauterine
infusion or systemically with hormonal treatment.
The most predisposing factor for uterine infection
was retained placenta (13.3%). The most
prevalent bacteria in uterine lumen were E. coli
(23%), Archanobacterium pyogenes (13%) and
Staphylococcus aureus (10%) were mostly
isolated from buffaloes with repeat breeding.
Vaginal mucus character score was associated
with the bacterial growth density score. The
difference in PMN was highly significant (p <
0.01) in animals with repeat breeding than control
groups. In addition, PMNs was significantly (p <
0.01) correlated r = 0.894 with the character of
vaginal discharge. High level of PMNs observed in
buffaloes infected with A. pyogenes. Buffalo cows
with endometritis had higher CK (321.47 ± 39.06
vs 162.01 ± 16.41 U/l) and AST (133.93 ± 12.43
vs 97.01 ± 6.86 U/l) activities (p < 0.05) than
control-heifers, but no significant difference was
observed between buffalo cows with endometritis
in CK (321.47 ± 39.06 vs 208.33 ± 5.84) and AST
(133.93 ± 12.43 vs 156.17 ± 9.65) activities than
control-pluriparious. It could be concluded that A.
pyogenes was the only non-specific uterine
pathogen directly associated with severe
endometrial lesions. Vaginoscopy examination
combined with palpation of uterus increase the
accuracy of diagnosing endometritis and cytogenic
examination of uterine discharge is more reliable
method of establishing the presence or absence of
uterine inflammation in buffalo cows. Animals with
repeat breeding (endometritis) showed clinical
cure and improved pregnancy in all treatment
groups with no significant difference. The use of
oestradiol in repeat breeder cases has no effect in
improving neither clinical cure rate nor pregnancy
rate.
Animal Reproduction Science 109 (2008) 100–109
Superovulatory response in a bovine model of
reproductive aging
Pritpal S. Malhia, Gregg P. Adamsa, Reuben J. Mapletoftb,
Jaswant Singha
a
Department of Veterinary Biomedical Sciences, Western College of
Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
S7N 5B4. bDepartment of Large Animal Clinical Sciences, Western
College of Veterinary Medicine,
University of Saskatchewan, Saskatoon, Canada S7N 5B4
Two experiments were done to test the
hypotheses that aging in cattle is associated with
9
Noticias de Reproducción Bovina
a reduced number of follicles recruited into an
ovarian follicular wave, and a reduction in the
ovarian response to gonadotropin treatment.
Older cows (13–16 years of age) and their
daughters (3–6 years of age) were treated with
FSH for ovarian superstimulation four times over
two
consecutive
years
(31
and
33
superstimulations in old and young cows,
respectively, experiments and years combined). In
Experiment 1, ovulation was induced using LH. In
Experiment 2, cumulus-oocyte complexes were
collected by ultrasonographic-guided follicle
aspirations before expected ovulations. The
ovarian follicular and ovulatory responses were
monitored daily by ultrasonography. Fewer 2–
5mm follicles (P < 0.01) were detected at the
expected time of follicular wave emergence in
older cows than in their daughters. After
superstimulation, older cows had fewer follicles
≥6mm (P < 0.01), and tended (P = 0.1) to have
fewer ovulations than their daughters (32±4
versus 40±3, respectively). There was a positive
correlation in the response of individual cows to
successive superstimulatory treatments (r > 0.8;
P < 0.0001) and the number of detected
ovulations from one year to the next (r = 0.6; P =
0.04). In conclusion, aging was associated with
fewer 2–5mm follicles at follicular wave
emergence and a lesser follicular and ovulatory
response after superstimulatory treatment. The
follicular
and
ovulatory
response
after
superstimulation
was
repeatable
within
individuals, regardless of age.
[email protected]
Theriogenology 70 (2008) 1544–1549
Delayed treatment with GnRH agonist, hCG and
progesterone and reduced embryonic mortality in
buffaloes
G. Campanilea, D. Vecchioa, R. Di Paloa, G. Negliaa, B.
Gasparrinia, A. Prandib, L. Zicarellia, M.J. D’Occhioc
a
DISCIZIA, Faculty of Veterinary Medicine, ‘‘Federico II’’ University,
V.F. Delpino 1, Naples 80137, Italy. bDSA, Udine University, Italy.
c
School of Animal Studies, Faculty of Natural Resources, Agriculture
and Veterinary Science, University of Queensland, Gatton Campus,
Queensland 4343, Australia.
The present study examined the effect of delayed
treatment with tropic hormones and progesterone
(P4) on embryonic mortality in buffaloes.
Buffaloes with a conceptus on Day 25 after AI
were assigned to the following treatments:
Control (n = 41), i.m. physiological saline; GnRH
agonist (n = 36), i.m. 12 mg buserelin acetate;
DICIEMBRE 2008
hCG (n = 33), i.m. 1500 IU hCG; P4 (n = 38), i.m.
341 mg P4 every 4 days on three occasions.
Control buffaloes had an embryonic mortality of
41.4% (17/41) between Days 25 and 45, and this
was reduced (P < 0.01) by treatment with GnRH
agonist (11.1%, 4/36), hCG (9.0%, 3/33) and P4
(13.1%, 5/38). On Day 45, buffaloes treated with
hCG and which ovulated had greater (P < 0.05)
concentrations of P4 in whey (453 ± 41 pg/ml)
than buffaloes in the same treatment that did not
ovulate (297 ± 32 pg/ml). A similar but nonsignificant trend was observed for buffaloes
treated with GnRH agonist. It was concluded from
the findings that the treatment of buffaloes on
Day 25 after AI with tropic hormones or P4 is
beneficial to processes associated with embryonic
implantation.
[email protected]
Reprod Dom Anim 43, 744–746 (2008)
A Competitive Dipstick Enzyme Immunoassay for
Diagnosis of Early Pregnancy in Bovine
S Venkatesa Perumal, V Umapathi, T Ambwani and BD
Lakhchaura
Department of Veterinary Biochemistry and Animal Biotechnology
Centre, College of Veterinary and Animal Sciences, G.B. Pant
University of Agriculture & Technology, Pantnagar, Uttarakhand,
India.
Early pregnancy diagnosis in bovines is one of the
important aspects in efficient dairy farm
management. In order to develop a competitive
enzyme immunoassay (EIA) employing low cost
reagents, anti-progesterone antiserum and
progesterone-penicillinase enzyme conjugate were
prepared. Using this antiserum and conjugate
along with pencillinV–starch–iodine substrate
system, the competitive EIA was standardized. In
the experiment, danazol, a weak androgen used
to extract the progesterone bound to proteins in
milk, was included after standardizing the
optimum concentration. Incubation period and
temperature and pH of the reaction mixture were
also optimized. The developed test was validated
with milk samples obtained from dairy farm and
individual animal owners. Confirmation of the
pregnancy was made by per rectum examination
of the genital tract around 60 days postinsemination. The user friendly test procedure
showed sensitivity and specificity of 83.3% and
87.5%, respectively as compared with residual
binding method which was earlier developed in
the laboratory with sensitivity and specificity of
100% and 87.5% respectively.
10
Noticias de Reproducción Bovina
Animal Reproduction Science 109 (2008) 65–76
Evaluation of short estrus synchronization methods in
dairy cows
Ümüt Cirita, Suleyman Bacinoglua, Muzaffer Taşb, Kamber
Demira, Ahmet Başc, Kemal Aka, İrfan Kamuran İleria
a
Istanbul University, Faculty of Veterinary Medicine, Department of
Reproduction and Artificial Insemination, 34320 Avcilar, Istanbul,
Turkey. bDicle University, Faculty of Veterinary Medicine, Department
of Reproduction and Artificial Insemination, 21280 Diyarbakir,
Turkey. cGeneral Directorate of Agricultural Enterprises (TİGEM),
Directorate of Agricultural Enterprises of Türkgeldi, Lüleburgaz,
Kırklareli, Turkey.
In the present study, two newshort estrus
synchronization methods have been developed for
lactating dairy cows. The study was completed in
three consecutive phases. In experiment (Exp) 1,
32 cows, that were not detected in estrus since
calving between the 50th and 84th post-partum
days, were treated with PGF2α (PGF, dcloprostenol, 0.150 mg), estradiol propionate (EP,
2 mg) and GnRH (lecirelina, 50 µg) at 24 h
intervals, respectively, and timed artificial
insemination (TAI) was performed 48 h after PGF.
Different from Exp 1, EP and GnRH were given at
48 and 60 h, respectively after PGF in Exp 2 (n =
20), instead of 24 and 48 h. Ovulations were
investigated by ultrasound for 7 days starting
from the day of PGF treatment, and ovulation
rates were compared with the ones obtained in
Exp 1. In Exp 3, cows were given the same
treatments as Exp 2, but treatments started at
certain estrus stages. Cows detected in estrus and
with a confirmed ovulation (n = 27) after the
second PGF given 11 days apart were assigned to
three treatment groups. Treatment was initiated
at Day 3 (group metestrus, n = 9), Day 12 (group
diestrus, n = 9) and Day 18 (group proestrus,
n=9) after ovulation. All cows included in Exp 3
were TAI between 16 and 20 h after GnRH
treatment. In Exp 2 and 3, blood samples were
obtained once every 2 days, starting from Day 0
to the 10th day after GnRH injection, and once
every 4 days between the 10th and the 22nd days
after GnRH to examine post-treatment luteal
development. During the study, animals exhibiting
natural estrus were inseminated and served as
controls (n = 85). The rate of estrus was found to
be significantly higher in cows with an active
corpus luteum (CL) at the start of Exp 1 (72.7%
vs. 30.0%, P < 0.05) and the pregnancy rate
tended to be higher than cows without an active
CL (40.9% vs. 10.0%, P = 0.08). Compared to
those in Exp 1, cows in Exp 2 had higher rates of
DICIEMBRE 2008
synchronized ovulation (94.1% vs. 59.1%, P =
0.013). In Exp 3, estrus (P < 0.001) and
pregnancy rates (P = 0.01) were found to be
significantly higher in cows in the proestrus group
than in those in the metestrus group. Comparable
pregnancy rates were obtained from the first and
second inseminations in Exp 1 and 3 with results
from those inseminated at natural estrus (P >
0.05). It was concluded from the study that the
treatment in Exp 1 and 3 could result in
comparable pregnancy rates after timed AI of
lactating dairy cows at random stages of the
estrus cycle relating to those
inseminated at
natural estrus, but the stage of the estrus cycle
can have significant effects on pregnancy rates.
[email protected]
Theriogenology 70 (2008) 1560–1568
Effects of scrotal insulation in Nellore bulls (Bos taurus
indicus) on seminal quality and its relationship with in
vitro fertilizing ability
C.E. Fernandesa, M.A.N. Dodeb, D. Pereirab, A.E.D.F. Silvac
a
Departamento de Patologia, Centro de Ciências Biológicas e da
Saúde, Universidade Federal de Mato Grosso do Sul, 79070-900
Campo Grande, MS, Brazil. bEmbrapa Recursos Genéticos e
Biotecnologia, W5 Norte, 70770-990 Brasília, Distrito Federal, Brazil.
c
Faculdade de Medicina Veterinária e Zootecnia, UNESP, 18618-000
Campus de Botucatu, SP, Brazil.
The objectives of this study were to assess the
effects of induced testicular degeneration in Bos
taurus indicus (Nellore) bulls on changes in
seminal characteristics and fertilizing ability of
sperm. Four Nellore bulls (30–36-month-old, 500–
550 kg) with good seminal quality (>80% motile
and morphologically normal sperm) had scrotal
insulation applied for 5 d. Semen was collected by
electroejaculation and cryopreserved at the preinsulation moment, and 7, 14, and 21 d after
insulation was removed. Gross motility, vigor of
sperm movement (1–5), acrosome integrity,
sperm morphology (phase-contrast microscopy),
nuclear vacuoles and abnormal chromatin
(Feulgen-stain) were determined after sperm
preparations for in vitro fertilization (IVF). Prior to
IVF, sperm were separated using a Percoll
gradient (45% and 90%). Normal sperm
decreased (P < 0.05) 14 and 21 d after insulation
was removed. On 14 and 21 d, the incidence of
head defects (9.7±0.6 and 17.0±0.8, respectively;
mean ± S.E.M.) was higher (P < 0.05) in
agreement with the incidence of nuclear vacuoles
(14.0±5.0 and 12.3±2.3) and abnormal chromatin
(24.4±7.2 and 30.8±2.8). Although the frequency
11
Noticias de Reproducción Bovina
of cleaved oocytes decreased only on 21 d (P <
0.05), blastocyst rates were lower (P < 0.05) than
pre-insulation on 14 and 21 d. In regression
analyses, only nuclear vacuoles, head defects and
intact acrosome accounted for differences in
cleavage (R2=0.38, 0.48, and 0.30, respectively)
and blastocyst rates (R2=0.35, 0.37, and 0.44).
Abnormal chromatin was associated only with
blastocyst rates (R2 = 0.35). In conclusion,
blastocyst rate was more sensitive than cleavage
rate and the assessment of nuclear integrity is
recommended to predict the fertilizing ability of
bull sperm.
[email protected]
Animal Reproduction Science 109 (2008) 77–87
Effect of timing of estradiol benzoate administration
upon synchronization of ovulation in suckling Nelore
cows (Bos indicus) treated with a progesteronereleasing intravaginal device
H. Ayresa, C.M. Martinsa, R.M. Ferreirab, J.E. Melloa, J.H.
Domingueza, A.H. Souzaa, R. Valentinc, I.C.C. Santosc, P.S.
Barusellia
a
Departamento de Reprodução Animal, FMVZ-USP, Rua Prof. Orlando
Marques de Paiva 87, CEP 05508-000, São Paulo, SP, Brazil.
b
Departamento de Medicina Veterinária Preventiva e Reprodução
Animal, FCAV-UNESP, Via Acesso Prof. Dr. Paulo Donato Castellane
s/n, CEP 14850-000, Jaboticabal, SP, Brazil. cTecnopec Cons C. R.
Ltda, Rua Emílio de Sousa Docca, 480 Vila Sta. Catarina, CEP 04379020, São Paulo, SP, Brazil.
The present study investigated how the timing of
the administration of estradiol benzoate (EB)
impacted the synchronization of ovulation in fixedtime artificial insemination protocols of cattle. To
accomplish this, two experiments were conducted,
with EB injection occurring at different times: at
withdrawal of the progesterone-releasing (P4)
intravaginal device or 24 h later. The effectiveness
of these times was compared by examining
ovarian follicular dynamics (Experiment 1, n = 30)
and conception rates (Experiment 2, n = 504). In
Experiment 1, follicular dynamics was performed
in 30 Nelore cows (Bos indicus) allocated into two
groups. On a random day of the estrous cycle
(Day 0), both groups received 2 mg of EB i.m.
and a P4-releasing intravaginal device, which was
DICIEMBRE 2008
removed on Day 8, when 400 IU of eCG and 150
µg of GF were administered. The control group
(G-EB9; n = 15) received 1 mg of EB on Day 9,
while Group EB8 (G-EB8; n = 15) received the
same dose a day earlier. Ovarian ultrasonographic
evaluations were performed every 8 h after device
removal until ovulation. The timing of EB
administration (Day 8 compared with Day 9) did
affect the interval between P4 device removal to
ovulation (59.4±2.0 h compared with 69.3±1.7 h)
and maximum diameter of dominant (1.54±0.06 a
cm compared with 1.71±0.05 b cm, P = 0.03)
and ovulatory (1.46±0.05 a cm compared with
1.58±0.04 b cm, P < 0.01) follicles. In Experiment
2, 504 suckling cows received the same treatment
described in Experiment 1, but insemination was
performed as follows: Group EB8-AI48h (G-EB8AI48h; n = 119) and Group EB8-AI54h (G-EB8AI54h; n = 134) received 1 mg of EB on Day 8
and FTAI was performed, respectively, 48 or 54 h
after P4 device removal. Group EB9-AI48h (GEB9-AI48h; n = 126) and Group EB9-AI54h (GEB9-AI54h; n = 125) received the same
treatments and underwent the same FTAI
protocols as G-EB8-AI48h and G-EB8-AI54h,
respectively; however, EB was administered on
Day 9. Conception rates were greater (P < 0.05)
in G-EB9-AI54h [63.2% (79/125) a], GEB9-AI48h
[58.7% (74/126) a] and G-EB8-AI48h [58.8%
(70/119) a] than in G-EB8-AI54h [34.3% (46/134)
b].We concluded that when EB administration
occurred at device withdrawal (D8), the interval to
ovulation shortened and dominant and ovulatory
follicle diameters decreased. Furthermore, when
EB treatment was performed 24 h after device
removal, FTAI conducted at either 48 or 54 h
resulted in similar conception rates. However, EB
treatment on the same day as device withdrawal
resulted in a lesser conception rate when FTAI
was conducted 54 h after device removal.
[email protected]
12
Noticias de Reproducción Bovina
DICIEMBRE 2008
Artículos de Revisión
Animal Reproduction Science 109 (2008) 1–16
Oestrous synchronisation in cattle—Current options
following the EU regulations restricting use of
oestrogenic compounds in food-producing animals: A
review
E.A. Lanea, E.J. Austinb, M.A. Croweb,c
Centre for Veterinary Epidemiology and Risk Analysis, Veterinary
Sciences Centre,
University College Dublin, Belfield, Dublin 4, Ireland. bSchool of
Agriculture, Food Science and Veterinary Medicine, Veterinary
Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland.
c
Conway Institute, University College Dublin, Belfield, Dublin 4,
Ireland.
the European ban on oestrogenic compounds
being used for oestrous synchrony protocols.
Currently, the options available for oestrous
synchronization are generally not as effective,
efficient or cost effective as those that
incorporated use of oestrogenic compounds.
mark.crowe@ucd
a
Oestrous synchronisation is an important strategy
to improve reproductive management of cattle.
The use of oestradiol-17β, and its related ester
derivatives, in food-producing cattle for the
purposes of oestrous synchronisation is prohibited
in the European Union since October 2006; a
serious limitation in the implementation of largescale use of cost effective synchronisation
regimens in both dairy and beef herds. This has
obvious consequences within the EU and also in
other countries that have restricted the use of
oestradiol following the EU ban. Oestrous
synchronisation is an important facilitator for the
use of artificial insemination, a necessary part of
any national herd genetic improvement scheme.
Presently, only 35% of the Irish dairy herd is bred
by artificial insemination; and facilitation rather
than restriction is required to increase this
percentage. Ideally synchronisation of oestrus
should increase submission rates, improve or at
least not affect conception rates, and thus,
increase overall pregnancy rate at the end of the
breeding season. This should reduce the
proportion of cows to be culled. This paper aims
to review the oestrous synchrony options available
in EU countries and other countries affected by
Domestic Animal Endocrinology 35 (2008) 325–342
The role of endocrine insulin-like growth factor-I (IGF-I)
in female bovine reproduction
M.A. Velazqueza, L.J. Spicerb, D.C. Wathesc
Escuela Superior de Ciencias Agropecuarias, Universidad Autónoma
de Campeche, Calle 53 s/n, C.P. 24350, Escárcega, Campeche,
Mexico. bDepartment of Animal Science, Oklahoma State University,
Stillwater, OK 74078, USA. cReproduction, Genes and Development
Group, Department of Veterinary Basic Sciences, Royal Veterinary
College, London AL9 7TA, UK.
a
Insulin-like growth factor-I (IGF-I) plays a pivotal
role in cattle fertility, acting as a monitoring signal
that allows reproductive events to occur when
nutritional conditions for successful reproduction
are reached. However, endocrine IGF-I is not a
predictor of reproductive events, but rather an
indirect estimator of the suitability of the animal
to achieve the reproductive event in question.
Although
measuring
circulating
IGF-I
concentrations might not have any clinical
application in the cattle industry, endocrine IGF-I
screening will continue to be important for the
study of interactions between nutrition and
reproduction. In addition, endocrine IGF-I
screening could be used as an ancillary test for
the selection of cattle for high reproductive
potential, especially in herds of high genetic merit
for milk production, in which a decline in fertility
has been identified.
lestaurus [email protected]
13
Noticias de Reproducción Bovina
DICIEMBRE 2008
Fisiología Reproductiva
Animal Reproduction Science 109 (2008) 50–64
Effect of different thawing rates on post-thaw sperm
viability, kinematic parameters and motile sperm
subpopulations structure of bull semen
R. Muiñoa, M.M. Riverab, T. Rigaub, J.E. Rodriguez-Gilb, A.I.
Peñaa
a
Unit of Reproduction and Obstetrics, Department of Animal
Pathology, Faculty of Veterinary Medicine of Lugo, University of
Santiago de Compostela, 27002 Lugo, Spain. bUnit of Animal
Reproduction, Department of Animal Medicine and Surgery, School of
Veterinary Medicine, Autonomous University of Barcelona, Bellaterra,
Spain.
The aim of the present study was to evaluate
three thawing rates for bull semen frozen in 0.25ml straws: placing the straws in a water bath at
37 ºC for 40 s, at 50 ºC for 15s or at 70 ºC for 5
s. In a first experiment, the three thawing rates
were compared in relation to post-thaw sperm
motility, determined subjectively, and sperm
plasma and acrosomal membrane integrity,
examined by flow cytometry, after 0 and 5 h of
incubation at 37 ºC. In a second experiment, the
three thawing rates were evaluated based on
post-thaw sperm motility, determined using a
CASA system, after 0 and 2 h of incubation at 37
ºC. In addition, for the motile spermatozoa, the
individual motility descriptors were analysed using
a multivariate clustering procedure to test the
presence of separate sperm subpopulations with
specific motility characteristics in the thawed bull
semen samples. Finally, it was investigated if the
thawing rate had any influence on the relative
frequency distribution of spermatozoa within the
different subpopulations. In terms of overall
postthaw motility or plasma and acrosomal sperm
membrane integrity there were no significant
differences between the three thawing methods
evaluated. The statistical analysis clustered all the
motile
spermatozoa
into
four
separate
subpopulations
with
defined
patterns
of
movement: (1) moderately slow and progressive
sperm (27%); (2) “hyperactivated-like” sperm
(15.4%); (3) poorly motile non-progressive sperm
(34.3%); (4) fast and progressive sperm (23.3%).
The thawing rate had no significant influence on
the frequency distribution of spermatozoa within
the four subpopulations, but there was a
significant effect (P < 0.05) of the interaction
between thawing rate and incubation time. Higher
proportions of spermatozoa with fast and
progressive movement were observed after 2 h of
post- thaw incubation when the thawing was at
the faster rates (35 ºC/40 s: 8.3%, 50 ºC/15 s:
18.1% and 70 ºC/5 s: 16.5%). Whether this
subtle difference might affect to the in vivo
fertility of the thawed bovine semen is not known.
[email protected]
Reprod Dom Anim 43, 713–719 (2008)
Effect of Protease Inhibitors on the Acrosome Reaction
and Sperm-Zona Pellucida Binding in Bovine Sperm
M Deppe1, P Morales2 and R Sánchez3
Center of Reproductive Biotechnology, Department of Basic
Sciences, Faculty of Medicine, De La Frontera University, Temuco;
2
Department of Biomedicine, Faculty of Health Sciences, University of
Antofagasta, Antofagasta; 3Center of Reproductive Biotechnology,
Department of Preclinical Science, Faculty of Medicine, De La
Frontera University, Temuco, Chile.
1
Acrosomal proteases participate in several events
during fertilization process and are necessary
during the acrosome reaction (AR) and spermzona pellucida (ZP) binding process. In this study,
the
participation
of
sperm
trypsin-like,
chymotrypsin- like, and metalloprotease enzymes
in the AR and ZP binding in cattle was
investigated using protease inhibitors. Motile
bovine sperm were obtained by a swim-up
method (4X106 cells⁄ml) in Brackett and Oliphant
medium. The sperm were capacitated and then
incubated with Antithrombin III (trypsin and
N-a-p-tosyl-Lchymotrypsin
inhibitor);
lysinechloromethyl-ketone
(trypsin
inhibitor);
Trypsin inhibitor (I-S Type from soybean); N-tosylL-phenylalanine-chloromethylketone (chymotrypsin inhibitor);
or
disodium
salt
from
the
hydrated
ethylenediaminetetraacetic acid (metalloprotease
inhibitor). Then, the AR was induced with
lysophosphatidylcholine and evaluated with the
double stain technique. Sperm zona binding
capacity was evaluated using cumulus cell-free
oocytes. A significant decrease (p < 0.05) in the
percent of true acrosome-reacted sperm was
observed only in cells incubated with trypsin (10.2
± 1%) and chymotrypsin inhibitors (18.5 ± 1%)
in relation to the control (52.2 ± 1%). Treatment
with the metalloprotease inhibitor did not affect
the AR percentage (51.8 ± 1%). On the contrary,
there was no significant change in the number of
sperm bound to the ZP with any of the inhibitors
used. The results suggest a role for trypsin and
14
Noticias de Reproducción Bovina
chymotrypsin
proteases,
but
not
metalloproteases, in the AR in bovine sperm. In
addition, these proteases do not seem to be
involved in the binding of bovine sperm to the ZP.
Reproduction (2008) 136 543–557
Propagation of bovine spermatogonial stem cells in
vitro
Pedro M Aponte1,2, Takeshi Soda1, Katja J Teerds3, S Canan
Mizrak4, Henk J G van de Kant1 and Dirk G de Rooij1,4
1
Departments of Endocrinology and Metabolism, Faculty of Science,
Utrecht University and of Cell Biology, UMCU, 3584 CH Utrecht, The
Netherlands, 2Department of Biomedical Sciences, Faculty of
Veterinary Sciences, Central University of Venezuela, Aragua State,
PO Box 4563, Maracay, Venezuela, 3Department of Animal Sciences,
Wageningen University, 6709 PJ Wageningen, The Netherlands and
4
Center for Reproductive Medicine, Academic Medical Hospital, 1105
AZ Amsterdam, The Netherlands.
The
access
to
sufficient
numbers
of
spermatogonial stem cells (SSCs) is a prerequisite
for the study of their regulation and further
biomanipulation. A specialized medium and
several growth factors were tested to study the in
vitro behavior of bovine type A spermatogonia, a
cell population that includes the SSCs and can be
specifically stained for the lectin Dolichos biflorus
agglutinin. During short-term culture (2weeks),
colonies appeared, themorphology of which varied
with the specific growth factor(s) added.
Whenever the stem cell medium was used, round
structures reminiscent of sectioned seminiferous
tubules appeared in the core of the colonies.
Remarkably, these round structures always
contained type A spermatogonia. When leukemia
inhibitory factor (LIF), epidermal growth factor
(EGF), or fibroblast growth factor 2 (FGF2) were
added, specific effects on the numbers and
arrangement of somatic cells were observed.
However, the number of type A spermatogonia
was significantly higher in cultures to which glial
cell line-derived neurotrophic factor (GDNF) was
added and highest when GDNF, LIF, EGF, and
FGF2 were all present. The latter suggests that a
proper stimulation of the somatic cells is
necessary for optimal stimulation of the germ cells
in culture. Somatic cells present in the colonies
included Sertoli cells, peritubularmyoid cells, and a
few Leydig cells. A transplantation experiment,
using nude mice, showed the presence of SSCs
among the cultured cells and in addition strongly
suggested amore than 10 000-fold increase in the
number of SSCs after 30 days of culture. These
results demonstrate that bovine SSC self-renew in
our specialized bovine culture system and that
DICIEMBRE 2008
this system can be used for the propagation of
these cells.
[email protected]
Animal Reproduction Science 109 (2008) 88–99
Metabolic requirements associated with GSH synthesis
during in vitro maturation of cattle oocytes
C.C. Furnusa,b,d, D.G. de Matosc, S. Piccoa,d, P. Peral Garcíaa,
A.M. Indab,e, G. Mattiolif, A.L. Errecaldeb
a
Centro de Investigaciones en Genética Básica y Aplicada (CIGEBA),
Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata,
La Plata (CP 1900), Buenos Aires, Argentina. bCátedra de Citología,
Histología y Embriología “A”, Facultad de Ciencias Médicas,
Argentina. cReproductive Medicines Associates, New Jersey, USA
d
CONICET, Argentina. eCIC, Argentina. fCátedra de Fisiología,
Facultad de Ciencias Veterinarias, UNLP, Argentina.
Glutathione (GSH) concentration increases in
bovine oocytes during in vitro maturation (IVM).
The constitutive amino acids involved in GSH
synthesis are glycine (Gly), glutamate (Glu) and
cysteine (Cys). The present study was conducted
to investigate the effect of the availability of
glucose, Cys, Gly and Glu on GSH synthesis during
IVM. The effect of the amino acid serine (Ser) on
intracellular
reduced/oxidized
glutathione
(GSH/GSSG) content in both oocytes and cumulus
cells was also studied. Cumulus–oocyte complexes
(COC) of cattle obtained from ovaries collected
from an abattoir were matured in synthetic
oviduct fluid (SOF) medium containing 8 mg/ml
bovine serum albumin-fatty acid-free (BSA-FAF),
10 µg/ml LH, 1µg/ml porcine FSH (pFSH) and 1
µg/ml 17 beta-estradiol (17β-E2). GSH/GSSG
content was measured using a double-beam
spectrophotometer. The COC were cultured in
SOF supplemented with 1.5mM or 5.6mM glucose
(Exp. 1); with or without Cys + Glu + Gly (Exp.
2); with the omission of one constitutive GSH
amino acid (Exp. 3); with 0.6mM Cys or Cys + Ser
(Exp. 4). The developmental capacity of oocytes
matured in IVM medium supplemented with Cys
and the cell number per blastocyst were
determined (Exp. 5). The results reported here
indicate (1) no differences in the intracellular
GSH/GSSG content at any glucose concentrations.
Also, cumulus cell number per COC did not differ
either before or after IVM (Exp. 1). (2)
Glutathione content in oocytes matured in SOF
alone were significantly different from oocytes
incubated with SOF supplemented with Cys + Glu
+ Gly (Exp. 2). (3) Addition of Cys to maturation
medium, either with or without Gly and Glu
supplementation resulted in an increase of
GSH/GSSG content. However, when Cys was
15
Noticias de Reproducción Bovina
omitted from the IVM medium intracellular GSH in
oocytes or cumulus cells was less but not
significantly altered compared to SOF alone (Exp.
3). (4) Glutathione content in both oocytes and
cumulus cells was significantly reduced by
incubation with 5mMSer (Exp.4). (5) There was a
significant increase in cleavage and blastocyst
rates when Cys was added to maturation medium.
In contrast, the cleavage, morula and blastocyst
rates were significantly different when 5mM Ser
was added to maturation media. There was also a
significant difference in mean cell number per
blastocyst, obtained from oocytes matured with
5mM Ser (Exp. 5). This study provides evidence
that optimal embryo development in vitro is
partially dependent on the presence of precursor
amino acids for intracellular GSH production.
Moreover, the availability of Cys might be a critical
factor for GSH synthesis during IVM in cattle
oocytes. Greater Ser concentration in IVM medium
altered “normal” intracellular GSH in both oocytes
and cumulus cells with negative consequences for
subsequent developmental capacity.
[email protected]
BIOLOGY OF REPRODUCTION 79, 1219–1225 (2008)
Antral Follicle Count Reliably Predicts Number of
Morphologically Healthy Oocytes and Follicles in
Ovaries of Young Adult Cattle
J.L.H. Ireland,3 D. Scheetz,3 F. Jimenez-Krassel,3 A.P.N.
Themmen,6 F. Ward,7 P. Lonergan,7 G.W. Smith,4 G.I. Perez,5
A.C.O. Evans,7 and J.J. Ireland2,3
Molecular Reproductive Endocrinology Laboratory,3 Laboratory of
Mammalian Reproductive Biology and Genomics,4 Department of
Animal Science, and Physiology Department,5 Michigan State
University, East Lansing, Michigan 48824. Department of Internal
Medicine,6 Erasmus MC, Rotterdam 3000 DR, The Netherlands.
School of Agriculture, Food Science, and Veterinary Medicine,7 and
Conway Institute, College of Life Sciences, University College Dublin,
Dublin 4, Ireland.
Methods to predict numbers of healthy oocytes in
the ovaries of young adults could have important
diagnostic relevance in family planning and animal
agriculture. We have observed that peak antral
follicle count (AFC) determined by serial ovarian
ultrasonography during follicular waves is very
highly reproducible within individual young adult
cattle, despite 7-fold variation among animals.
Herein, we tested the hypothesis that AFC is
positively associated with the number of
morphologically healthy oocytes and follicles in
ovaries and with serum concentrations of antiMüllerian hormone (AMH), an indirect marker for
number of healthy follicles and oocytes in ovaries.
DICIEMBRE 2008
In the present study, age-matched young adult
cattle (12–18 mo old) were subjected to serial
ultrasonography to identify animals with a
consistently high (≥25 follicles that were ≥3 mm
in diameter) or low (≤15 follicles) AFC during
follicular waves. Differences in serum AMH
concentrations, ovary weight, and number of
morphologically healthy and atretic follicles and
oocytes were determined. The phenotypic
classifications of cattle based on AFC during
follicular waves or AMH concentrations both
predict reliably the relative number of
morphologically healthy follicles and oocytes in
ovaries of age-matched young adult cattle.
[email protected]
Reproduction, Fertility and Development, 2008, 20,
884–891
Development and quality of bovine morulae cultured in
serum-free medium with specific retinoid receptor
agonists
Enrique Gómez, Aida Rodríguez, Marta Muñoz, José Néstor
Caamaño, Susana Carrocera, David Martín, Nieves Facal and
Carmen Díez
ASERIDA, Camino de los Claveles 604, Somió, 33205 Gijón, Spain.
Retinoids
regulate
development
and
differentiation of the bovine blastocyst in vitro,
although the underlying mechanisms remain to be
clarified.
A
challenge
in
reproductive
biotechnology is the identification of pathways
that regulate early embryonic development and
their influence on blastocyst differentiation,
apoptosis and survival to cryopreservation as
traits of embryo quality. The present paper
analyses the effects of short-term exposure (24 h)
to retinoids on in vitro produced bovine morulae.
Immature cumulus oocyte complexes were in vitro
matured and fertilised. Presumptive zygotes were
subsequently cultured in modified synthetic
oviduct fluid up to Day 6, in which morulae were
randomly allocated to the different experimental
groups. The treatments consisted of 0.1µm
LG100268 (LG; a retinoid X receptor agonist),
0.7µm all-trans retinoic acid (ATRA; a retinoic acid
receptor agonist) or no additives. Day 8 blastocyst
development was increased in the ATRA-treated
group compared with the LG and untreated
embryos. In Day 7 embryos, the number of total
cells and cells allocated to the trophectoderm
were higher in the ATRA-treated group compared
with untreated embryos. Apoptosis in the inner
cell mass increased after LG treatment, whereas
16
Noticias de Reproducción Bovina
ATRA had no effect. After vitrification and
warming, survival and hatching rates of Day 7
blastocysts did not change with retinoid
treatment. Within the LG treated and untreated
blastocyst groups, survival and hatching rates
were higher for Day 7 than Day 8 embryos;
however, Day 8 blastocysts treated with ATRA
showed improved hatching rates. In conclusion,
treatment of morulae with ATRA in serum-free
medium improves embryo development and
quality without increasing the incidence of
apoptosis and necrosis.
[email protected]
Reprod Dom Anim 43, 672–677 (2008)
Influence of Heat Stress on the Cortisol and OxidantAntioxidants Balance During Oestrous Phase in BuffaloCows (Bubalus bubalis): Thermo-protective Role of
Antioxidant Treatment
GA Megahed1, MM Anwar2, SI Wasfy2 and ME Hammadeh3
1
Department of Theriogenology, Faculty of Veterinary Medicine;
2
Department of Physiology, Faculty of Medicine, Assiut University,
Assiut, Egypt; 3Department of Obstetrics and Gynaecology, Faculty of
Human Medicine, University of Saarland, Homburg ⁄ Saar, Germany.
In the present study, the effect of heat stress,
which is commonly observed in the animals of
Upper Egypt area in summer, as well as the effect
of antioxidant treatment as a thermo-protective
was examined. In this study, the animals (n =
120) were divided into winter group (n = 40, bred
during winter) and summer group (n = 80, bred
during summer) as well as, animals in the
summer group were divided into first subgroup
animals (n = 40) and injected with Viteselen
intramuscularly (15 ml) twice weekly for 10 weeks
and second subgroup animals (n = 40) were not
treated (as control). Serum levels of progesterone
(P4), oestradiol (E2), cortisol, superoxide
dismutase (SOD), lipid peroxidase (LPO) and nitric
oxide (NO) were measured. The pregnancy rate of
all animals was detected rectally. The levels of
oestradiol and the activity of the antioxidant SOD
were decreased in serum of animals in
behavioural oestrus during summer as compared
with those in winter. During the same time period
the levels of oxidants such as LPO and NO were
increased in the serum of animals again in the
phase of oestrus. In another group of animals
treated by intramuscular injection with 15 ml
viteselen (antioxidant) twice weekly for 6 weeks
during hot months, the activities of serum SOD
showed an increase and the levels of oxidants and
DICIEMBRE 2008
cortisol decreased. Moreover, the levels of
oestradiol were increased during the oestrous
behaviour. The pregnancy rate was decreased in
animals under heat stress and the pregnancy rate
was enhanced dramatically when these animals
received antioxidants during the heat stress. This
means that the heat-stress in Upper Egypt may
affect the fertility of animals and pregnancy rate
and this effect may be through an increased
production of free radicals and decreased
production of antioxidants as well as increased
levels of cortisol. Treatment of animals or
supplementation with antioxidants before the
beginning of months of heat-stress and also
during the stress period may correct the infertility
due to heat-stress through the decrease in cortisol
secretion and a decrease in the oxidative stress.
These results resulted in an increase in pregnancy
rate in treated animals.
Reprod Dom Anim 43, 720–729 (2008)
Oviductal Fluid Proteins Associated with the Bovine
Zona Pellucida and the Effect on In Vitro Sperm–Egg
Binding, Fertilization and Embryo Development
RF Gonçalves, AL Staros and GJ Killian
Department of Animal Reproduction, College of Veterinary Medicine
and Animal Science, São Paulo University, Cidade Universitária, SP,
Brazil. Department of Dairy and Animal Science, The John O.
Almquist Research Center, The Pennsylvania State University,
University Park, PA, USA.
Studies have demonstrated that oviductal fluid
(ODF) proteins associate with eggs of numerous
species including the bovine. In this study, the
association of three ODF proteins, the bovine
oestrus-associated protein, osteopontin (OPN),
lipocalin-type prostaglandin D synthase (L-PGDS),
with the bovine zona pellucida (ZP) was
demonstrated by immunohistochemistry and
western blot. The biological function of ODF
derived egg-associated OPN and L-PGDS in sperm
binding, fertilization and embryonic development
was also explored. In vitro matured bovine
oocytes were preincubated with ODF collected by
cannula from cows in oestrus, or ODF with
antibodies to OPN, L-PGDS and bovine serum
albumin (BSA). Following incubation, oocytes
were inseminated with 1 X 105 frozen-thawed
spermatozoa, and they were evaluated for sperm
binding, fertilization and embryonic development
in vitro. Pre-treatment of ODF with antibodies to
all of proteins reduced sperm binding to the ZP
and fertilization in vitro. Cleavage rates were not
17
Noticias de Reproducción Bovina
significantly different among incubations, but
rates of embryo development were significantly
decreased. We conclude that antibodies to OPN,
L-PGDS and BSA react with oocytes incubated
with ODF and inhibit sperm binding, fertilization
and embryonic development in vitro, suggesting a
potential role of these proteins in these events.
The Veterinary Journal 178 (2008) 208–213
Differential alterations in the ability of bovine
neutrophils to generate extracellular and intracellular
reactive oxygen species during the periparturient
period
Manuela Rinaldia, Paolo Moronia, Max J. Paapeb, Douglas D.
Bannermanb
a
Department of Veterinary Pathology, Hygiene and Public Health,
University of Milan, 20133, Italy. bBovine Functional Genomics
Laboratory, US Department of Agriculture, Agricultural Research
Service, Beltsville, MD 20705, USA.
The periparturient period of a dairy cow is
associated with increased incidence and/or
severity of certain infectious diseases, including
mastitis. It is believed that the heightened
physiological demands of calving and initiation of
milk production contribute to a state of
immunosuppression during this period. Previous
studies have indicated that neutrophil production
of reactive oxygen species (ROS), which is a
critical element of the host innate immune
response to bacterial infection, is impaired in the
1–2 week period following calving. However,
whether there is comprehensive inhibition of ROS
production or selective inhibition of particular ROS
remains unknown. The present study provides
evidence that neutrophils isolated from cows (n =
20) after calving have an increased capacity to
generate intracellular ROS and an impaired ability
to release extracellular superoxide anion and
hydrogen peroxide.
[email protected]
Reprod Dom Anim 43, 647–655 (2008)
The Role of Platelet-activating Factor in the Mammalian
Female Reproductive Tract
U Tiemann
Department of Reproductive Biology, Research Institute for the
Biology of Farm Animals, Dummerstorf, Germany.
Platelet-activating factor (PAF) is a potent lipid
mediator produced by various cell types of
mammals and is involved in an inflammatory-like
process with increased vascular permeability.
Platelet-activating factor exerts its actions through
the activation of specific PAF receptors (PAF-R)
DICIEMBRE 2008
found in cells and tissues of the female
reproductive tract. The aim of this article was
summarized briefly in the current research on the
role of PAF in female reproductive functions.
Platelet-activating factor has been implicated in
processes of ovulation, implantation and
parturition because of its angiogenic and growth
factor properties. This factor is influenced by
ovarian steroid hormones in bringing about
changes in the uterus and is a candidate molecule
for initial embryo–maternal dialogue. Tissue
concentrations of PAF are regulated by the
equilibrium between biosynthesis and degradation
by PAF-acetylhydrolase (PAF-AH). Antagonists of
PAF interfere with ovulation and implantation.
Platelet-activating factor, its receptor, and PAFAH
activity play an important role in the maintenance
of pregnancy.
Animal Reproduction Science 109 (2008) 27–39
Identification of sperm subpopulations with defined
motility characteristics in ejaculates from Holstein
bulls: Effects of cryopreservation and between-bull
variation
R. Muiñoa, C. Tamargob, C.O. Hidalgob, A.I. Peñaa
Unidad de Reproducción y Obstetricia, Departamento de Patología
Animal, Facultad de Veterinaria, Universidad de Santiago de
Compostela (USC), 27002 Lugo, Spain. bÁrea de Selección y
Reproducción Animal, Servicio Regional de Investigación y Desarrollo
Agroalimentario (SERIDA), 33203 Somió, Gijón, Asturias, Spain.
a
The aims of the present study were: (1) to
determine the existence of sperm subpopulations
with specific motility characteristics in fresh
ejaculates from Holstein bulls, (2) to investigate
the effects of semen cryopreservation and postthaw incubation on the distribution of
spermatozoa within the different subpopulations,
and (3) to evaluate the existence of between-bull
variation in the sperm subpopulations structure of
fresh and frozen-thawed semen. Six ejaculates
were collected from each of 9 Holstein bulls and
cryopreserved following a standard protocol.
Overall sperm motility and the individual kinematic
parameters of motile spermatozoa, determined
using a CASA system, were evaluated before
freezing and after 0, 2 and 4 h of post-thaw
incubation at 37 ºC. Data from 16,740 motile
spermatozoa, defined by VCL, VSL, VAP, LIN,
STR, WOB, ALH and BCF, were analysed using a
multivariate clustering procedure to identify and
quantify specific subpopulations within the semen
samples. The statistical analysis clustered all the
18
Noticias de Reproducción Bovina
motile
spermatozoa
into
four
separate
subpopulations with defined patters of movement:
Subpopulation (Subp. 1) moderately slow but
progressive spermatozoa (23.2%), (Subp. 2)
highly active but non-progressive spermatozoa
(16.0%), (Subp. 3) poorly motile non-progressive
sperm (35.5%), and (Subp. 4) highly active and
progressive sperm (25.3%). Subpopulations 2 and
4 significantly (P < 0.01) decreased during
cryopreservation and post-thaw incubation (Subp.
2: 21.1%, 18.1%, 8.7% and 5.9%; and Subp. 4:
34.1%, 20.6%, 15.2% and 7.3%, respectively, for
fresh, 0, 2 and 4 h post-thaw) whereas Subp. 3
significantly (P < 0.01) increased (10.7%, 27.2%,
27.2% and 30.7%, respectively, for fresh, 0, 2
and 4 h post-thaw). The frequency distribution of
spermatozoa within subpopulations was quite
similar for the 9 bulls, either in fresh or frozen–
thawed semen, and differences among bulls were
mainly due to differences in the Subp. 4.
DICIEMBRE 2008
Significant correlations (P < 0.01) were found
between the proportions of spermatozoa assigned
to Subp. 4 in the fresh ejaculates and those in
frozen-thawed semen after 0 (r = 0.473), 2 (r =
0.513) and 4 h post-thaw (r = 0.450). This
indicated that the ejaculates with the highest
subpopulations of rapid and progressive sperm
were also the most resistant to cryopreservation
and showed the best post-thaw sperm longevity
were found between the proportions of
spermatozoa assigned to Subp. 4 in the fresh
ejaculates and those in frozen-thawed semen
after 0 (r = 0.473), 2 (r = 0.513) and 4 h postthaw (r = 0.450). This indicated that the
ejaculates with the highest subpopulations of
rapid and progressive sperm were also the most
resistant to cryopreservation and showed the best
post-thaw sperm longevity.
[email protected]
Próximos eventos
CURSO TEÓRICO-PRÁCTICO DE INSEMINACIÓN ARTIFICIAL
EN BOVINOS
Fecha: 15 al 18 enero de 2009.
Sede: Centro de Enseñanza, Práctica e Investigación en
Producción y Salud Animal (CEPIPSA)
Informes: [email protected]
CURSO TEÓRICO-PRÁCTICO SOBRE TRANSFERENCIA DE
EMBRIONES EN BOVINOS
Fecha: 29 - 31 enero de 2009.
Sede (Teórico): Auditorio Pablo Zierold Reyes, FMVZ-UNAM
Sede (Práctico): Centro de Enseñanza, Práctica e
Investigación en Producción y Salud Animal (CEPIPSA)
Informes: [email protected]
19
Noticias de Reproducción Bovina
DICIEMBRE 2008
Sitios de interés
Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación
http://www.sagarpa.gob.mx
Confederación Nacional de Organizaciones Ganaderas
http://www.cnog.com.mx
Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias
http://www.inifap.gob.mx
Facultad de Medicina Veterinaria y Zootecnia
http://www.fmvz.unam.mx
Academia Veterinaria Mexicana, A.C.
http://www.academiaveterinaria.org
Asociación Mexicana de Médicos Veterinarios Especialistas en Bovinos, A.C.
http://www.AMMVEB.net
Federación de Colegios y Asociaciones de Médicos Veterinarios Zootecnistas de México, A.C.
www.fedmvz.com
Organización de las Naciones Unidas para la Agricultura y la Alimentación
www.fao.org
Organización Panamericana de la Salud.
www.cinu.org.mx/onu/estructura/mexico/org/ops.htm
Revista Veterinaria México
http://www.fmvz.unam.mx/fmvz/revvetmex/revvetmex.htm
Dirección General de Salud Animal
http://senasicaw.senasica.sagarpa.gob.mx/portal/html/salud_animal/introduccion
/introduccion.html
American Dairy Science Association (ADSA)
http://www.adsa.org/
Dairy and Animal Science (The Pennsylvania State University)
http://www.das.psu.edu/
College of Agriculture. Animal & Food Sciences (University Of Kentucki)
http://www.uky.edu/Ag/AnimalSciences/index.html
Electronic Zoo (NetVet Vterinary Resourcs –Cows Sites)
http://netvet.wustl.edu/cows.htm#dairy
Dairy Cattle Nutrition UW-Extension (University of Wisconsin)
http://www.uwex.edu/ces/dairynutrition/
Fundación Española para el Desarrollo de la Nutrición Animal
http://www.etsia.upm.es/fedna/introtablaf.htm
JOHNE´s Infomation Center (University of Wisconsin)
http://www.johnes.org/
20
Noticias de Reproducción Bovina
DICIEMBRE 2008
21