Influence of sex, slaughter weight and carcass weight on “non

Small Ruminant Research 60 (2005) 247–254
Influence of sex, slaughter weight and carcass weight on
“non-carcass” and carcass quality in segureña lambs
F. Peña a, ∗ , T. Cano b , V. Domenech a , Ma.J. Alcalde c , J. Martos a ,
A. Garcı́a-Martinez a , M. Herrera a , E. Rodero a
a
b
Departamento Producción Animal, Universidad de Córdoba, Campus Universitario de Rabanales,
Carretera Madrid-Córdoba km. 396, C.P. 14071 Córdoba, Spain
Oficina Comarcal Agraria La Loma, Av. Cristo Rey, Hospital de Santiago, 23400 Úbeda, Jaén, Spain
c Departamento de Ciencias Agroforestales, Escuela de Ingenierı́a Técnica Agrı́cola,
Universidad de Sevilla, Ctra. Utrera km. 1, 41013 Sevilla, Spain
Received 27 December 2002; received in revised form 21 December 2004; accepted 21 December 2004
Available online 25 February 2005
Abstract
The effects of sex, slaughter weight and carcass weight on carcass characteristics and meat quality traits were evaluated using
100 Segureña lambs. The management of all lambs was similar prior to slaughter at 19–25 kg. Slaughtered animals with a hot
carcass weight below 20 kg were assigned to class B, and those greater than 22 kg to class C. Carcass weight had a significant
influence on “non-carcass” components, dressing percentage, subjective carcass conformation, fat deposits, carcass fatness, bone
and most carcass measurements. Sex had a significant effect on age at slaughter, “non-carcass” components, rib measurements,
dressing percentage, fat deposits, and neck and shoulder percentage. As the weight increased, the carcass measurements also
increased. Concurrently, while improving the conformation indices of the carcass, leg and dressing percentages, neither the
commercial cuts of the animal nor tissue composition was significantly affected. Sex primarily affected the quantity of all types
of fat deposits.
© 2005 Elsevier B.V. All rights reserved.
Keywords: Lamb; Carcass; Non-carcass components; Sex; Slaughter weight
1. Introduction
The increasing demand for meat and meat products has led to studies on the carcass and meat char∗ Corresponding author. Tel.: +34 957 418738;
fax: +34 957 218667.
E-mail address: [email protected] (F. Peña).
0921-4488/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.smallrumres.2004.12.011
acteristics of sheep breeds and the influence of age
and weight at slaughter (Field et al., 1990). Criteria for the European carcass classification system in
lambs (European Union, 1994) are based on carcass
weight, meat colour and degree of subcutaneous fat
in carcasses under 13 kg. The classification is also established by comparing photographic patterns. Furthermore, three classes of cold-carcass weight (CCW)
248
F. Peña et al. / Small Ruminant Research 60 (2005) 247–254
(≤7, 7.1–10 and 10.1–13 kg) reflect the market price of
lambs. Environmental conditions in Spain and the consumer preferences for lamb meat favour the precocious
sheep breeds, slaughtered at an early age of 75–90 days
(19–26 kg of live weight). The light carcass (9–12.5 kg)
includes classes B and C of the European carcass classification system. The Segureña, with 1,275,000 animals
raised in the Southeast of Spain, is a rustic-type breed,
typical of the Mediterranean region which excel as light
lambs. These animals have short wool and ewes weigh
50–65 kg at maturity. The carcass weight of Segureña
lamb, in relation to the requirements of both producer
and consumer, and influence of sex, were evaluated.
2. Materials and methods
In this study 100 Segureña lambs weaned at 40–50
days of age were fed a creep ration consisting of 88.3%
dry matter, 19.2% crude protein, 2.9% crude fat and
5.7% ash, from 15 days. After weaning, the lambs were
fed a commercial ration, based on concentrate (88.2%
dry matter, 17.5% crude protein, 3.5% crude fat, 8.0%
ash) and cereal straw, until slaughter.
All lambs slaughtered at 19–25 kg live weight, were
classified (European Union, 1994) and processed according to the methodology of Colomer-Rocher et al.
(1988). The digestive contents and offal were weighed.
The “non-carcass” body components were grouped
into “caidos” (head, skin and feet), “red offal” (lung,
trachea, heart, thymus, liver and spleen), “white offal”
(empty digestive tract) and “fat depots” (pericardic fat,
mesenteric fat and omental fat). The empty live weight
(ELW) was estimated by subtracting the digestive content from the slaughter weight (SW). Hot carcasses
were weighed (HCW) and graded for conformation (1:
poor to 5: excellent), fatness (1: low to 5: very high) and
kidney fatness (1: without fat to 5: completely covered
with great thickness of fat) using the EUROP system
for light lambs (Colomer-Rocher et al., 1988). After
chilling at 4 ◦ C for 24 h, carcasses were again weighed
to determine the cold-carcass weight.
The objective carcass conformation measurements
and indices, as described by Palsson (1939) and
Boccard et al. (1958), were as follows: internal carcass length (L), hind limb length (F), buttock width
(G), buttock perimeter (BG), thoracic perimeter (PT),
thoracic depth (Th), carcass compactness (CCW/L),
G/F, Th/L, Th/G, L/G, L/PT and hind limb compactness (leg weight/F). The carcasses were split along the
spine and measured at the cross-section of the 13th
rib for maximum width (A) and depth (B) of the m.
longissimus thoracis, subcutaneous fat thickness (C)
along the prolonged line of the measurement B and
over the m. serratus dorsalis caudalis (J). The subjective evaluation of meat colour (1: pale, to 5: red
dark) for m. rectus abdominis (Sierra, 1974) was based
on chilled carcass (24 h post-mortem). At 24 h postmortem, the left side was separated into commercial
joints (shoulder, neck, ribs, loin, leg, breast and tail)
and dissected into muscle, bone, subcutaneous fat, intermuscular fat and tissues (Colomer-Rocher et al.,
1988; Fisher and de Boer, 1994). At the same time, the
muscle/bone (M/B) and muscle/fat (M/F) indices were
determined.
The mathematical model for the analysis of noncarcass and carcass quality included a fixed effect due
to sex, body weight class (7–10 and 10.1–13 kg) and
residual error. Data were analysed using the Statgraphic
four statistical package for Windows. The interaction
was not significant and, therefore, excluded.
3. Results
The distribution of the carcasses according to carcass weight and sex is presented in Table 1. Class B
included 30% of the slaughtered lambs and the remaining 70% were in class C. Slaughtered lambs weighing
under 20 kg were mostly class B carcasses; those over
22 kg were class C and those with 20–22 kg in both
classes. Lambs slaughtered at an average of 79 days
weighed 21.4 kg (Table 2). There were no significant
effect of sex on weight at slaughter, nevertheless, females took 6 days longer to reach slaughter weight.
There were no significant effect of sex on slaughter
weight, empty live weight and hot carcass weight, but
weight class B and C were different (P < 0.05). The average dressing percentage, 48% (CCW/SW) and 55%
(HCW/ELW), was greater in females than males and
there was a significant and positive effect of slaughter
weight. The non-carcass components were 35% of the
empty body weight. With increased carcass weight, the
non-carcass components/ELW decreased significantly.
There were significant effects of sex on the non-carcass
components.
F. Peña et al. / Small Ruminant Research 60 (2005) 247–254
249
Table 1
Carcasses distribution in Segureña light lambs
Slaughter weight (kg)
Carcass class
B
C
8.1–9 kg
M
19.0–20
20.1–21
21.1–22
22.1–23
23.1–24
24.1–25
Carcass distribution (%)
9.1–10 kg
10.1–11 kg
11.1–12 kg
12.1–13 kg
M
F
M
F
1
3
4
1
5
6
3
1
3
F
M
F
M
F
2
4
8
2
4
7
3
2
5
6
9
4
3
5
6
3
2
28
43
23
4
M, male; F, female.
The “caidos” were 35% of the empty live weight,
followed by “white offals” (9%), “red offals” (6%)
and lastly the “fat deposits” (3%). These percentages increased with carcass weight (17.0% versus
16.7%; 9.9% versus 9%; 6.0% versus 5.6%; 2.7%
versus 2.9%). The percentages of “caidos”, red offals and white offals were greater in males, while
fat deposits were greater in females. In general, both
classes of carcass meet Spanish market requirements of
medium–high conformation, medium–low fatness and
Table 2
Mean (±S.E.) for weight class and sex of dressing percentage, non-carcass characteristics and carcass subjective evaluation of Segureña light
lambs
Trait
Mean
Age (day)
SW (kg)
ELW (kg)
HCW (kg)
HCW/SW (%)
HCW/ELW (%)
HCW/SW (%)
CCW/ELW (%)
Nc/ELW (%)
Caidos/ELW (%)
Caidos/Nc (%)
Red offals/ELW (%)
Red offals/Nc (%)
White offals/ELW (%)
White offals/Nc (%)
Fat depots/ELW (%)
Fat depots/Nc (%)
CC
CF
KF
Meat colour
79.1
21.4
19.1
10.5
49
55
48
53
35
17
48
6
16
9
27
3
8
2.3
2.6
2.6
1.3
Carcass class
B (8.1–10 kg)
77.4a
20.4a
18.3a
9.9a
48.3a
54.1a
47.1a
52.7a
35.4a
17.0a
48.1a
5.8a
16.4a
9.9a
27.8a
2.7a
7.7a
2.2a
2.5a
2.6a
1.3a
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
2.16
0.21
0.18
0.09
0.33
0.32
0.32
0.31
0.30
0.20
0.40
0.10
0.30
0.20
0.20
0.39
0.30
0.07
0.06
0.06
0.06
Sex
C (10.1–13 kg)
80.9a
22.4b
19.9b
11.1b
49.5b
55.6b
48.4b
54.3b
34.2b
16.7a
48.7a
5.6a
16.5a
9.0a
26.4b
2.9a
8.4b
2.5b
2.7b
2.7a
1.4a
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
1.54
0.15
0.13
0.06
0.23
0.24
0.23
0.22
0.20
0.10
0.30
0.10
0.20
0.10
0.30
0.10
0.20
0.05
0.04
0.04
0.04
Females
82.0a
21.3a
19.0a
10.4a
49.0a
55.1a
47.9a
53.8a
34.3a
16.5a
48.2a
5.6a
16.3a
9.1a
26.4a
3.1a
9.2a
2.4a
2.8a
2.9a
1.4a
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
1.97
0.19
0.16
0.08
0.30
0.29
0.29
0.04
0.30
0.29
0.30
0.09
0.30
0.29
0.30
0.09
0.29
0.07
0.05
0.05
0.06
Males
76.2b
21.6a
19.2a
10.5a
48.8a
54.5a
47.5a
53.2a
35.3b
17.2b
48.7a
5.9a
16.6a
9.9b
27.8b
2.4b
6.9b
2.3a
2.4b
2.3b
1.3a
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
1.77
0.17
0.14
0.07
0.28
0.26
0.26
0.26
0.30
0.10
0.30
0.10
0.20
0.10
0.30
0.10
0.21
0.06
0.05
0.05
0.05
Note: a, b means within a row within weight class or sex, not followed by the same superscript differ (P < 0.05); SW: slaughter weight; ELW:
empty live weight; HCW: hot carcass weight; CCW: cold-carcass weight; Nc: non-carcass body components; CC: carcass conformation; CF:
carcass fatness; KF: kidney fatness.
F. Peña et al. / Small Ruminant Research 60 (2005) 247–254
250
clear meats. Nevertheless, it is important that females
do not exceed ideal levels of fatness (CF = 2.5–3.5;
fat deposits < 3.5%). The average carcass conformation
score was 2.3, which shows well-formed carcasses that
improved with increase in weight.
In the group ≤10 kg, 63% of the carcasses were classified as conformation 2, and 37% as conformation 3,
while in the group >10 kg, 24% were classified as 2,
70% as 3, and 6% as 4. When the carcass weight increased, males showed a slightly higher quality carcass
score than females.
Subjective evaluation of carcass and kidney fatness
(Table 3) showed an average value of 2.6. Therefore
the majority were classified as medium fat with 2/3covered kidney. The scores for kidney fat and carcass
fat were higher in females than males. With the increase
Table 3
Subjective evaluation of carcass conformation, carcass fatness, renal fatness and meat colour
Carcass class
Sex
Scoresa
1
2
3
9 (64)
10 (63)
Total
Total
Carcass conformation
B: ≤10 kg
Females
Males
C: >10 kg
Females
Males
Scores
Factors
P-value
Mean
P-value
3
5 (36)
6 (37)
NS
NS
Sex
NS
2.36
2.38
NS
19 (63)
11 (37)
**
**
Weight
**
2.33
*
17 (24)
49 (70)
NS
*
Sex
*
2.81
2.82
NS
Sex
NS
3.07
2.69
*
Weight
*
2.87
*
3.19
2.91
*
4 (6)
2.81
11 (79)
11 (69)
2 (4)
NS
NS
Total
6 (20)
22 (73)
2 (7)
*
NS
Total
3 (4)
60 (86)
7 (10)
4 (11)
NS
3.06
7 (19)
NS
Sex
3 (9)
29 (81)
31 (91)
**
12 (86)
13 (81)
2 (14)
NS
Sex
NS
3.14
2.81
NS
3 (19)
Total
3 (10)
25 (83)
2 (7)
2.97
NS
Total
4 (6)
53 (76)
13 (18)
4 (12)
24 (67)
39 (85)
12 (33)
1 (3)
Females
Males
C: >10 kg
4
Association
2
1 (7)
5 (31)
Kidney fatness
B: ≤10 kg
Females
Males
Meat colour
B: ≤10 kg
1
29 (81)
20 (60)
Females
Males
C: >10 kg
4
7 (19)
10 (29)
Carcass fatness
B: ≤10 kg
Females
Males
C: >10 kg
P-value (scores)
NS
NS
NS
Weight
NS
NS
**
Sex
*
3.33
2.91
*
Sex
NS
1.86
1.81
NS
Weight
NS
1.83
NS
3.19
Females
Males
3 (21)
3 (19)
10 (71)
13 (81)
1 (7)
NS
NS
Total
6 (20)
23 (77)
1 (3)
NS
NS
Total
10 (14)
57 (82
3 (4)
Females
Males
4 (11)
6 (18)
31 (86)
26 (76)
1 (3)
2 (6)
NS
1.90
NS
NS
NS
Sex
NS
1.92
1.88
NS
NS: P > 0.05.
a Absolute and relative frequences (%) respect to its group; carcass conformation from 1 (poor conformation) to 4 (better conformation);
carcass and renal fatness from 1 (low fat) to 4 (high fat); meat colour from 1 (pale meat) to 4 (reddish meat).
* P < 0.05.
** P < 0.01.
F. Peña et al. / Small Ruminant Research 60 (2005) 247–254
in carcass weight, the scores of kidney and carcass fat
also increased (2.5–2.7; 2.2–2.5, respectively), but differences were only evident in the latter. Subjective evaluation of muscle colour showed an average value of 1.3,
indicating that the majority of the Segureña lamb car-
251
casses had pink muscles. Carcass weight and sex had
no significant influence in muscle colour.
Table 4 shows the effect of carcass weight and sex
on carcass measurements and indices. Carcass weight
classification influenced the majority of carcass mea-
Table 4
Mean (±S.E.) for carcass measurements and indices, measurements of rib steak (m. longissimus thoracis), carcass commercial joint and carcass
tissue composition in Segureña light lambs carcasses
Trait
Mean
L (cm)
F (cm)
BG (cm)
PT (cm)
G (cm)
Th (cm)
CCW/L (g/cm)
G/F
Th/L
Th/G
L/G
L/PT
Leg weight/F
A (mm)
B (mm)
C (mm)
J (mm)
B/A (%)
B/C (%)
Area (cm2 )
Neck (%)
Shoulder (%)
Loin (%)
Breast (%)
Ribs (%)
Leg (%)
Tail (%)
Kidney (%)
Kidney fat (%)
Pelvic fat (%)
Testi. fat (%)
Sub. fat (%)
Interm. fat (%)
Muscle (%)
Bone (%)
Othera (%)
Loss (%)
Meat/bone
Meat/fat
52.2
24.1
50.9
58.8
16.5
22.2
195.6
0.7
0.4
1.3
3.2
0.9
70.9
46.7
23.5
2.0
5.7
50
14
8.7
8
20
7
11
17
34
1
1
2
0.6
0.4
7
12
54
20
2.5
2.5
2.8
2.5
Carcass class
B (8.1–10 kg)
51.7a
24.1a
49.9a
58.1a
16.2a
21.9a
186.2a
0.67a
0.4a
1.4a
3.2a
0.9a
65.6a
46.5a
23.2a
1.8a
4.9a
50.1a
15.0a
8.5a
7.6a
20.2a
6.9a
11.0a
17.4a
34.0a
0.9a
0.9a
2.3a
0.5a
0.4a
6.4a
11.4a
54.5a
20.3a
2.5a
2.6a
2.7a
2.7a
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
0.30
0.20
0.30
0.19
0.10
0.10
1.59
0.01
0.01
0.12
0.03
0.01
0.80
0.80
0.50
0.10
0.30
0.90
1.10
0.30
0.10
0.10
0.20
0.30
0.20
0.20
0.10
0.10
0.10
0.04
0.04
0.30
0.41
0.50
0.20
0.10
0.10
0.16
0.09
Sex
C (10.1–13 kg)
Females
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
52.1a ±
23.9a ±
50.9a ±
58.5a ±
16.4a ±
21.9a ±
195.8a ±
0.7a ±
0.4a ±
1.4a ±
3.2a ±
0.9a ±
70.8a ±
45.5a ±
23.5a ±
2.2a ±
6.4a ±
51.5a ±
12.4a ±
8.4a ±
7.4a ±
19.9a ±
6.9a ±
11.6a ±
17.5a ±
33.8a ±
0.9a ±
0.9a ±
2.9a ±
0.7a ±
–
7.4a ±
12.3a ±
54.0a ±
19.2a ±
2.4a ±
2.5a ±
2.9a ±
2.4a ±
52.8b
24.0a
51.9b
59.6b
16.8b
22.5b
204.9b
0.72b
0.4a
1.3a
3.1a
0.9a
73.5b
47.0a
23.8a
2.1a
6.4b
50.6a
13.3a
8.8a
7.6a
20.1a
7.0a
11.5a
17.5a
33.5a
0.9a
0.9b
2.5a
0.6a
0.4a
7.0a
12.4b
53.9a
19.7b
2.3a
2.5a
2.8b
2.5b
0.20
0.10
0.20
0,20
0.10
0.10
1.10
0.01
0.01
0.01
0.01
0.01
0.84
0.60
0.30
0.10
0.20
0.70
0.80
0.20
0.10
0.10
0.10
0.21
0.20
0.20
0.10
0.10
0.10
0.03
0.03
0.20
0.30
0.40
0.20
0.10
0.10
0.03
0.01
Males
0.20
0.20
0.30
0.20
0.09
0.09
1.50
0.01
0.01
0.02
0.02
0.01
0.90
0.70
0.40
0.10
0.30
0.90
1.01
0.20
0.10
0.10
0.20
0.20
0.20
0.20
0.10
0.10
0.10
0.03
0.03
0.40
0.50
0.20
0.10
0.10
0.03
0.06
52.3a
24.2a
51.0a
59.2b
17.7b
22.4b
195.4a
0.7a
0.4a
1.3a
3.1a
0.9a
70.8a
48.0b
23.5a
1.8b
5.0b
49.2b
15.9b
8,9a
7.8b
20.3b
7.0a
11.0a
17.4a
33.7a
0.9a
0.9a
1.8b
0.5b
0.4
6.1b
11.5a
54.4a
20.9b
2.4a
2.5a
2.7b
2.7b
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
0.20
0.20
0.30
0.20
0.10
0.10
1.30
0.01
0.01
0.02
0.02
0.01
1.00
0.70
0.40
0.10
0.30
0.80
0.90
0.20
0.10
0.10
0.10
0.20
0.20
0.20
0.10
0.10
0.10
0.03
0.03
0.20
0.30
0.40
0.20
0.10
0.10
0.03
0.08
Note: a, b means within a row within weight class or sex, not followed by the same superscript differ (P < 0.05). L: internal carcass length;
F: hind limb length; G: buttock length; BG: buttock perimeter; PT: thoracic depth; CCW/L: carcass compactness; A: maximum width of the
m. longissimus thoracis; B: maximum depth of the m. longissimus thoracis; C: subcutaneous thickness of the m. longissimus thoracis; J:
subcutaneous thickness of the m. serratus dorsalis caudalis.
a Remaining tissues from dissection (mainly connective tissue).
252
F. Peña et al. / Small Ruminant Research 60 (2005) 247–254
surements, as well as the degree of compactness of the
carcass and the leg. These results indicated that carcass
measurements, carcass compactness and leg conformation increased with carcass weight. In addition, the sex
of the animal had little influence on carcass dimensions.
However, male carcasses were both deeper (Th), wider
(G) and more voluminous (PT).
There were no significant differences between the
<10 and >10 kg groups on any of the rib steak characteristics. However, there were significant effects of
sex on most of the rib steak characteristics. Differences
between sexes corroborated the previously stated observation regarding the greater degree of fatness in females. The commercial cuts showed values of 34% for
the leg, 20% for the shoulder, 17% for the ribs, 11% for
the breast, 8% for the neck, and 7% for the loin. Carcass
weight showed no significant effect on the proportion
of commercial cuts, but the leg varied from 34% in
the <10 kg group to 33.5% in the >10 kg group, and
the breast varied from 11 to 11.5% in the respective
groups.
Sex affected the proportion of commercial cuts only
in the neck and back, which were more developed in the
males. The carcass (Table 4) contained 22% fat, 54%
muscle and 20% bone. Carcass muscle content was approximately 54.5% for carcasses of less than 10 kg and
53.9% for those heavier than 10 kg; the bone percentage varied between 20.3 and 19.7%, and that of fat
21–23%. Female carcasses had a significantly higher
proportion of fat, similar to that found by Benevent
(1971), while the male carcasses had a heavier skeleton. The percentage of muscle was similar in both
sexes.
Weight at slaughter had a significant influence on
intermuscular fat and bone, which corresponded to
their allometric growth. The quantity of subcutaneous
fat also increased with slaughtering weight. Given the
great variability among animals, the difference was not
statistically significant.
4. Discussion
The lower growth rates of females associated with
greater age at slaughter are consistent with those reported by Falagan (1992) for the same breed. Slaughter
weight, empty live weight, hot carcass weight, dressing percentage and non-carcass components percent-
age were similar to those recorded in lambs slaughtered at same age and/or weight (Falagan, 1988; Peña
et al., 1989; Domenech et al., 1990; Ruiz de Huidobro
and Cañeque, 1993; Delfa et al., 1996; Alcalde et al.,
1999).
In agreement with previous studies (Ruiz de Huidobro and Jurado, 1989; Falagan, 1992; Santos et al.,
2000), the carcass yield was greater in females, possibly due to more fat, especially in the renal region.
The absence of statistical differences between sexes
could possibly be attributed to the range of slaughter
weights. With increased slaughter weight, the dressing percentage also increased, again in agreement with
Domenech et al. (1990), Sañudo et al. (1997), Vergara
et al. (1999) and Pérez et al. (2002). In contrast, De
la Fuente et al. (1999) found no variations of the carcass yield with the increase in live weight, while Cano
et al. (2003) obtained an allometric coefficient <1 in
Segureña lambs at the same weight.
The percentage of non-carcass components was
comparable to the figures from Peña et al. (1989), but
of a slightly lower valve than in other Spanish breeds
(Rasa Aragonesa, Roya Bilbilitana, Ojinegra de Teruel
and Rubia del Molar) at the same slaughter weight. This
is attributed to the lighter weight of the skin (8.2% of
the ELW; Peña et al., 1989) compared between to 9.5
and 13% recorded by other researchers (Alcalde et al.,
1999; Delfa et al., 1999; De la Fuente et al., 1999).
The Nc/ELW ratios decreased with slaughter
weight, in agreement with the results of Peña et al.
(1989) for the Segureña breed. However, De la Fuente
et al. (1999) reported a higher allometric coefficient at
70–90 days of age for the Rubia del Molar breed. This
difference can be explained by the different wool-type:
medium-wool in the Segureña breed and carpet-wool
in the Rubia del Molar breed.
The carcass measurements were lower than those
reported in lambs with similar slaughter weights
(Aparicio et al., 1989; Falagan, 1992; Ruiz de Huidobro
and Cañeque, 1993; Alcalde et al., 1999). Increase in
carcass measurements and the index of carcass conformation, along with the higher fatness, are the main
causes for the higher degree of subjective classification
of the carcass conformation of group C. However, females do not show better shaped carcasses than males
in contrast to the results of Vergara et al. (1999). The
higher measurement and index values for carcass compactness in males are compensated for a higher fat con-
F. Peña et al. / Small Ruminant Research 60 (2005) 247–254
tent in females, which eliminates differences in slaughter weight. When the animals are slaughtered at a later
age and heavier weight, females had better carcasse
conformation, which is in accordance with the allometric coefficient for fat covering (Aparicio et al., 1989;
Domenech et al., 1989).
The good level of fatness in these carcasses, despite
their relatively low weight, was due in great measure,
to the precocity of the Segureña breed, an observation which is confirmed when compared with results
for breeds or crossbreeds of greater adult weight, such
as Manchega (Ruiz de Huidobro and Cañeque, 1993;
Alcalde et al., 1999). Female carcasses have a higher
proportion of fat, in agreement with the figures reported
by Dı́az et al. (2002). M/B were higher in heavier carcasses and in males that were associated with a better conformation (Hopkins et al., 1997). The difference of fatness between sexes increased with carcass
weight (Domenech et al., 1989; Aparicio et al., 1989;
Santos et al., 2000). There was a higher percentage
of female carcasses with a score of 4 (Table 3). Therefore, the slaughter weight of females should not exceed
23–25 kg, while males may be more than 25–27 kg.
The males had carcass heavier than the females, in
agreement with previous results (Zurita et al., 1980;
Olleta et al., 1992). Possibly due to the physiology
of the male, which includes an advanced growth rate
and, consequently, a greater elongation of bones (Wylie
et al., 1997). No differences were detected between
sexes for buttock perimeter, contrary to the studies of
Colomer and Espejo (1972), and Ruiz de Huidobro and
Jurado (1989) that reported higher values for females,
attributed to anatomical adaptation for lambing. These
discrepancies are due to the differences in slaughter
weights.
The proportion of commercial cuts were similar
in both sexes, as reported by Zurita et al. (1980).
In contrast, Domenech et al. (1990) and Pérez et al.
(2002) found higher percentages in females. The correlation of percentage of commercial cuts with carcass
weight are in agreement with reported allometric coefficients (Domenech et al., 1990; Ruiz de Huidobro
and Cañeque, 1993; Pérez et al., 2002). Therefore, the
Segureña breed can be used for the production of both
types of carcass. This is because the fat content in females was 24% of the carcass, and the proportion of
pelvic and renal fat/carcass weight was about 4%. Exceeding these values would lead to carcass deprecia-
253
tion, indicating that the females should not be slaughtered at heavier weights.
5. Conclusion
The Segureña breed produces a carcass with good
conformation and fatness within 7–13 kg cold-carcass
weight. Weight class influenced mainly by slaughter
weight, and carcass fatness varied according to sex.
Therefore, the producer could increase the returns from
breeding and fattening by determining the appropriate
time for slaughter.
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