Body and carcass linear measurements of goats slaughtered at different weights

S Attah*, A O Okubanjo, A B Omojola and A O K Adesehinwa**

Meat Science Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria
abomojola@yahoo.com

^*Present Address: Department of Animal Production, University of Agriculture, Makurdi, Nigeria.

** Institute of Agricultual Research & Training, Obafemi Awolowo University,
PMB 5029, Moor Plantation, Ibadan. Nigeria.

Abstract

Body and carcass measurements were obtained from 9 each of Red Sokoto (RS) and West African Dwarf (WAD) male and female yearling goats. At the commencement of the experiment their initial body weight ranged between 5.47 and 8.82 kg. They were fed on a 16.8% crude protein concentrate diet and then slaughtered three per group at 10,15 or 20 kg body weight. Prior to slaughter, at the various predetermined slaughter weights, body measurements (height at withers, height at pelvis, width of chest , chest girth and width of pelvis) were carried out on each of the animals. After slaughter the hot carcass weight (HCW) was taken on the kill floor within 20 minutes post-mortem. The carcasses were chilled at 3C for approximately 24hr after which the various carcass measurements were carried out.

Body and carcass measurements that had to do with height and length of animals or their parts were significantly higher (P< 0.05) in the RS than the WAD. The males were significantly taller (P< 0.05) at 10 kg body weight. At 20 kg body weight, the males had significantly wider chest while the females had wider pelvis (P< 0.05). The width of pelvis, width of chest, chest girth, height at withers, height at pelvis and carcass depth of chest were at one stage of growth or the other found to be highly correlated with empty body weight (P< 0.05 - 0.001). The chest girth in all animals, width of chest in animals slaughtered at 10 and 20 kg body weights and the depth of chest (carcass) in animals slaughtered at 10 kg body weight were all highly correlated (P< 0.01) with dressing percentage.

Key Words: Body measurement, breed, carcass measurement, goats, sex

Introduction

Meat is a major source of animal protein in the human diet. In Nigeria, goats are kept mainly for meat although the skin is also valuable. Apart from taking live weight of meat animals, researchers also use other parameters such as body length, width of pelvis, height at withers and chest girths in order to adequately evaluate live animals. According to Srivastava et al (1968), body measurements are indices of skeletal development and indirectly help to determine carcass composition.

Another parameter that has been used over the years to estimate the amount of meat that could be obtained from slaughtered animals is carcass measurement. De Boer et al (1974) identified four types of linear carcass measurements. These include length of carcass, depth of chest, length of leg and width of leg.

In this study male and female goats of two breeds indigenous to West Africa were studied in order to determine their body and carcass measurements at three slaughter weights.

Materials and methods

Thirty six male and female goats of two breeds, the West African Dwarf (WAD) and the Red Sokoto (RS) were purchased in equal numbers by breed and sex from some goat farmers in Ibadan, South Western Nigeria. They were all purchased at about one and a half years of age with initial live weight range of between 5.47 and 8.82 kg. They were later assigned to a 2 x 2 x 3 factorial design and fed ad libitum with a 16.8% crude protein diet. Table 1 shows the composition of the experimental diet.

Table 1. Composition of experimental diet
Ingredient	Percentage
Maize	40.00
Dusa¹	29.00
Brewers Dry Grain	18.00
Groundnut cake	10.00
Bone Meal	1.00
Vit/Mineral Premix	2.00
Total	100.00
Determined Analysis
Moisture	8.00
Crude protein	16.80
Crude fibre	12.40
Ether extract	3.50
Nitrogen free extract	53.50
Ash	6.00
¹ By product of an alcoholic drink made from guinea corn

At the various predetermined slaughter weights of 10, 15 and 20 kg, body measurements namely height at withers, height at pelvis, width of chest, depth of chest, chest girth and width of pelvis were carried out using a measuring tape according to the method described by De Boer et al (1974).

When an animal reached a predetermined weight it was fasted for 24 hours, weighed and taken to the Department of Animal Science, University of Ibadan abattoir for slaughter. After slaughter the head, the skin and the feet were removed. The carcass was then eviscerated. The hot carcass weight (HCW) was taken on the kill floor within 20 min post-mortem.

The carcasses were chilled at 3ºC for approximately 24hr after which the cold carcass weights (CCW) were obtained. The carcass was split into two halves along the vertebral axis using a meat saw. The length of carcass, depth of chest, length of leg, maximum width of leg and width of leg from medial splitting surface were then measured following the procedure described by De Boer et al (1974).

Means and standard errors were determined on all data according to the following classifications: breed x weight level, sex x weight level and breed x sex. The data were subsequently subjected to analysis of variance appropriate to the design and Duncan's multiple Range Test (Steel and Torrie 1980) for separation of means. Data were then analysed by the regression procedure of statistical analysis system of Barr and Goodnight (1976). Individual animals were considered as experimental units.

Results and discussion

The data obtained on the experimental animals are summarized in Tables 2, 3 and 4. All the body and carcass measurements that had to do with height and length of animals or their parts such as height at withers, height at pelvis, carcass length and length of leg were significantly higher (P< 0.05) in the Red Sokoto (RS) than the West African Dwarf (WAD) (Tables 3 and 5). This was expected because the former is the taller of the two breeds. However, measurements like chest girth, width of chest and depth of chest (carcass) that related to fatness were generally higher in the WAD.

Table 2. Means and standard errors of body and carcass measurements by breed and slaughter weight
Variable	Slaughter weight (kg)
	10		15		20
	WAD	RS	WAD	RS	WAD	RS
Height at withers, cm	35.13±1.51^c	46.91±0.69^a	40.64±0.33^b	47.83±0.43^a	41.38±0.40^b	49.25±0.41^a
Height at pelvis, cm	39.36±1.74^d	50.07±0.64^b	45.29±0.49^c	51.33±0.39^b	47.29±0.34^c	59.50±0.64^a
Width of pelvis, cm	20.19±0.13^c	20.60±0.22^c	23.53±0.49^b	22.55±0.44^b	25.73±1.27^a	23.23±0.70^b
Depth of chest (live), cm	21.30±0.48^b	19.09±0.67^b	24.05±0.72^a	20.02±0.68^b	25.41±0.52^a	22.08±0.68^ab
Chest girth, cm	51.68±0.31^bc	50.40±0.08^c	58.64±0.55^a	53.93±0.32^b	58.25±1.72^a	55.13±0.59^ab
Width of chest, cm	17.87±0.36^b	16.22±0.10^b	29.25±0.85^a	26.98±0.13^a	30.13±0.78^a	27.52±0.46^a
Carcass length, cm	35.93±0.77^c	41.15±0.62^a	39.15±0.32^b	45.62±0.14^a	39.45±0.55^b	46.20±0.46^a
Hot carcass weight, kg	3.73±0.07^c	3.39±0.07^c	6.08±0.14^b	5.56±0.14^b	10.25±0.48^a	9.70±0.31^a
Empty body weight, kg	9.31±0.08^c	8.91±0.07^c	13.50±0.11^b	13.49±0.02^b	17.96±0.24^a	18.13±0.09^a
Chilled carcass weight, kg	3.47±0.06^c	3.09±0.05^c	5.79±0.15^b	5.11±0.10^b	10.00±0.48^a	9.38±0.30^a
Chilling loss, kg	0.27±0.01^c	0.30±0.02^b	0.31±0.06^b	0.45±0.08^a	0.25±0.03^c	0.33±0.04^b
Percent chilling loss	7.32±0.27^a	8.84±0.33^a	5.08±0.97^b	7.99±1.35^a	2.45±0.29^c	3.34±0.36^c
Dressing percentage¹	40.02±0.51^c	37.99±0.70^c	45.03±0.75^b	41.17±1.03^c	56.88±2.40^a	53.55±1.87^a
Depth of chest (carcass), cm	16.12±0.20	15.94±0.24	17.28±0.72	16.75±0.40	18.30±0.91	17.57±0.59
Length of leg, cm	24.43±0.31^b	28.45±0.55^a	23.78±0.58^b	28.46±0.42^a	24.04±0.57^b	28.70±0.59^a
Maximum width of leg, cm	4.68±0.15	4.93±0.34	4.95±0.12	5.13±0.14	5.48±0.48	5.88±0.36
Width of leg from medial splitting surface, cm	3.90±0.27	4.10±0.20	3.98±0.15	4.23±0.11	3.95±0.37	4.11±0.41
¹Based on empty body weight ^abcMeans in the same row without common superscripts are different at P<0.05.

Table 3. Means and standard errors of body and carcass measurements by sex and slaughter weight
Variable	Slaughter weight, kg
	10		15		20
	M	F	M	F	M	F
Height at withers, cm	43.44±2.26	38.60±3.03	44.72±1.77	43.76±1.50	45.78±1.82	44.85±1.77
Height at pelvis, cm	47.30±1.83^a	42.13±2.98^b	48.97±1.33^a	47.65±1.45^a	51.47±1.72^a	50.33±1.62^a
Width of pelvis, cm	20.77±0.25^c	20.22±0.07^c	22.05±0.24^c	24.03±0.28^b	22.35±0.34^c	26.60±0.90^a
Depth of chest (live), cm	21.42±0.43^bc	18.97±0.62^c	23.60±0.92^a	20.48±0.89^bc	24.91±0.70^a	22.58±0.91^ab
Chest girth, cm	51.41±0.41^b	50.67±0.21^b	57.08±1.24^a	55.49±0.92^a	58.13±1.42^a	55.25±1.20^a
Width of chest, cm	17.51±0.49^b	16.58±0.29^b	28.60±0.96^a	27.63±0.47^a	29.73±0.83^a	27.92±0.69^a
Carcass length, cm	38.75±1.44	38.33±1.26	42.68±1.44	42.10±1.49	43.45±1.62	42.20±1.55
Hot carcass weight, kg	3.64±0.10^c	3.48±0.09^c	6.08±0.13^b	5.56±0.15^b	10.20±0.40^a	9.75±0.43^a
Empty body weight, kg	9.11±0.15^c	9.11±0.06^c	13.60±0.06^b	13.39±0.06^b	18.35±0.11^a	17.74±0.14^a
Chilled carcass weight, kg	3.33±0.10^c	3.22±0.10^c	5.68±0.19^b	5.21±0.14^b	9.82±0.40^a	9.53±0.43^a
Chilling loss, kg	0.31±0.01	0.27±0.01	0.40±0.06	0.36±0.09	0.35±0.03	0.23±0.02
Percent chilling loss	8.48±0.48^a	7.69±0.34^a	6.68±1.16^a	6.38±1.50^a	3.46±0.31^b	2.33±0.26^b
Dressing percentage¹	39.86±0.50^c	38.15±0.79^c	44.66±0.78^b	41.55±1.24^b	55.88±2.21^a	54.54±2.30^a
Depth of chest (carcass), cm	16.36±0.08	15.70±0.23	17.88±0.57	16.15±0.30	18.89±0.67	16.98±0.64
Length of leg, cm	26.65±0.98	26.23±1.02	26.00±1.21	26.24±1.11	26.15±1.32	26.59±1.04
Maximum width of leg, cm	4.90±0.25	4.70±0.28	5.20±0.13	4.88±0.11	5.83±0.34	5.53±0.49
Width of leg from medial splitting surface, cm	4.08±0.22	3.93±0.26	4.18±0.13	4.03±0.15	4.21±0.39	3.85±0.38
¹Based on empty body weight ^abcMeans in the same row without common superscripts are different at P<0.05..

The male animals were generally taller in both breeds than their female counterparts, the differences being significant (P< 0.05) in animals slaughtered at 10 kg body weight. Both sexes have reached close to the peak height at withers for their class at 10 kg live weight with only insignificant increase in height to 20 kg weight. Indeed, Hall (1991) noted that height at withers rarely changes significantly with age.

Table 4 shows the effect of breed x sex interaction. There was no significant effect of this interaction as this table follows a similar pattern with those showing the breed and sex effects (Tables 2 and 3). The height at withers observed in both breeds here are generally lower than the ones recorded for the same breeds by Ngere et al (1979). While those workers used mature animals, the animals used in this work were not fully mature even at 20 kg body weight. However, the higher heights in male animals observed here were also reported by those workers.

Table 4. Means and standard errors of body and carcass measurements by breed and sex
Variable	Breed/Sex
Variable	WADM²	WADF³	RSM⁴	RSF⁵
Height at withers, cm	40.32±0.57^b	37.78±1.51^c	48.97±0.22^a	47.03±0.55^a
Height at pelvis, cm	42.68±0.68^b	42.26±1.75^c	52.80±0.67^a	51.12±0.80^a
Width of pelvis, cm	21.89±0.42^b	24.40±1.23^a	21.56±0.18^b	22.82±0.66^ab
Depth of chest (live), cm	24.77±0.65^a	22.41±0.63^b	21.85±0.45^b	18.94±0.48
Chest girth, cm	57.62±1.42^a	54.76±1.97^ab	53.45±0.79^b	52.84±0.75^b
Width of chest, cm	26.62±2.08	24.88±1.97	23.94±1.90	23.20±1.80
Carcass length, cm	38.50±0.80^b	37.85±0.65^b	44.75±0.89^a	43.90±0.93
Hot carcass weight, kg	6.89±1.00	6.48±0.96	6.38±0.95	6.04±0.93
Empty body weight, kg	13.85±1.31	13.32±1.19	13.52±1.36	13.50±1.30
Chilled carcass weight, kg	6.60±1.00	6.24±0.97	5.97±0.94	5.74±0.93
Chilling loss, kg	0.30±0.02^ab	0.26±0.04^b	0.41±0.04^a	0.31±0.05^ab
Percent chilling loss	5.04±0.73	4.86±0.96	7.37±0.95	6.07±1.14
Dressing percentage¹	48.14±2.73	46.48±2.76	45.46±2.41	43.01±2.69
Depth of chest (carcass), cm	18.33±0.56^a	16.12±0.39^b	17.08±0.43^ab	16.43±0.38^b
Length of leg, cm	23.95±0.43^b	24.21±0.38^b	28.58±0.49^a	28.49±0.33^a
Maximum width of leg, cm	5.18±0.20	4.88±0.30	5.43±0.27	5.18±0.27
Width of leg from medial splitting surface, cm	4.07±0.24	3.81±0.19	4.23±0.18	4.06±0.24
¹Based on empty body weight; ²West African Dwarf Male; ³West African Dwarf Female; ⁴Red Sokoto Male; ⁵Red Sokoto Female ^abcMeans in the same row without common superscripts are different at P<0.05..

Significant (P<0.05) increases in chest girth and width of chest were observed between 15 and 20 kg live weight. Depth of chest did not significantly increase in RS goat as weight increased from 10 to 20 kg but was observed to increase in WAD goats between 10 and 15 kg weight without appreciable increase thereafter. While the males had significantly wider chests (P<0.05), the females had significantly wider pelvis (P<0.05) especially at 20 kg body weight. Significant increase in width of pelvis of females from 10 kg to 20 kg but not in the corresponding males indicate greater measure of pubertal influence. Indeed, Butswat et al (1998) working with RS does recorded a market live weight in the range 17.2 to 17.8 kg for animals brought to the slaughter slab and which were observed to be at puberty. Okubanjo (1996) also reported that between 8.04% and 12.43% of such animals brought for slaughter were observed to be gravid and would therefore benefit from an enlarged pelvis if pregnancy were brought to term.

Carcass chilling loss decreased from 7.32% to 2.45% in WAD and from 8.84% to 3.34% in RS between 10 and 20 kg live weight while dressing percent increased significantly (P<0.05) from 40.0% to 56.9% in WAD and from 38.0% to 53.6% in RS. Decrease in exposed surface area as carcass weight increased and more efficient insulation due to increased fatness may be responsible for the protection against dehydration loss. Except at the 15 kg slaughter weight, there was no significant difference (P>0.05) in chilling loss between the breeds. Similarly no significant difference in chilling loss was attributable to sex effect at any slaughter weight. However, the chilling loss percent at 20kg slaughter weight was superior to those at 10 or 15 kg weight.

Lack of variation in carcass depth of chest among sexes and weight classes could be expected due to carcass posture assumed on hanging the carcass by the archilles tendon during chilling. This posture allows the chest cage to be pulled caudally and inwards by the abdominal muscles Obliquus abdominis externus and internus (Sisson and Grossman 1953) thereby reducing the depth of chest. The carcass length and carcass length of leg followed the same trend with RS being significantly (P<0.05) longer at each slaughter weight than the WAD. No significant (P>0.05) breed, sex or weight group effect was observed in either the maximum width of leg or the width of leg from the medial splitting surface.

The chest girth in all animals, width of chest in all animals slaughtered at 10 and 20kg body weights and depth of chest (carcass) in animals slaughtered at 10kg body weight were all highly correlated (P<0.01) with dressing percentage (Table 5). However, other linear measurements such as height at withers, height at pelvis and width of pelvis were negatively correlated with dressing percentage. In an earlier work, Devendra (1966) could not associate live measurements of female goats with carcass values but Rasheed (1977) found that chest girth in Buffalo vealers was strongly correlated with dressing percentage.

Table 5. Correlation between body and carcass linear measurements and dressing percentage at the three slaughter weights
Trait	Weight, kg	Sample size	Correlation coefficient
Height at withers	10	12	-0.38^ns
	15.	12	-0.56^ns
	20	12	-0.23^ns
Height at pelvis	10	12	-0.33^ns
	15	12	-0.52^ns
	20	12	-0.21^ns
Width of pelvis	10	12	-0.04^ns
	15	12	-0.11^ns
	20	12	-0.18^ns
Depth of chest (live animal)	10	12	0.83***
	15	12	0.90***
	20	12	0.53^ns
Chest girth	10	12	0.72**
	15	12	0.82**
	20	12	0.72**
Width of chest	10	12	0.75**
	15	12	0.65*
	20	12	0.77*
Carcass length	10	12	-0.35^ns
	15	12	-0.61*
	20	12	-0.03^ns
Depth of chest (carcass)	10	12	0.64*
	15	12	0.55^ns
	20	12	0.73**
Length of leg	10	12	0.43^ns
	15	12	-0.57^ns
	20	12	0.03^ns
Max. width of leg	10	12	0.24^ns
	15	12	0.36^ns
	20	12	0.59*
Width of leg from medial splitting surface	10	12	0.84***
	15	12	0.07^ns
	20	12	0.23^ns
ns = Not significant; * P<0.05; P<0.01; * P<0.001

Measurements such as width of pelvis, width of chest, chest girth, depth of chest (carcass), height at withers and height at pelvis were at one stage or the other found to be highly correlated with empty body weight (P< 0.05 - 0.001) (Table 6). This is in agreement with the findings of Ladipo (1973) who observed similar relationships between live animal measurements and empty body weight in male goats in the United States. Similarly the observed significant linear regression of body measurements on slaughter weight agrees with the findings of Gizaw (1995) who made the same observation in Ethiopian Horro sheep. The low correlations between certain linear measurements (height at withers, height at pelvis and width of pelvis) and dressing percentage observed in this study also agree with the observations of Devendra (1966) who could not associate live measurements on female goats with carcass value. However, other live measurements in the present study were strongly correlated with dressing percentage.

Table 6. Correlation between body and carcass linear measurements and empty body weight at the three slaughter weights
Trait	Weight, kg	Sample size	Correlation coefficient
Height at withers	10	12	-0.64*^s
	15	12	0.01^ns
	20	12	0.23^ns
Height at pelvis	10	12	-0.59*
	15	12	0.10^ns
	20	12	0.23^ns
Width of pelvis	10	12	-0.47^ns
	15	12	0.59*
	20	12	- 0.85***
Depth of chest (live animal)	10	12	0.48^ns
	15	12	0.41^ns
	20	12	0.22^ns
Chest girth	10	12	0.81***
	15	12	0.32^ns
	20	12	0.41^ns
Width of chest	10	12	0.77**
	15	12	0.57^ns
	20	12	0.27^ns
Carcass length	10	12	-0.56^ns
	15	12	0.07^ns
	20	12	0.31^ns
Depth of chest (carcass)	10	12	0.23ⁿ
	15	12	0.68*
	20	12	0.45^ns
Length of leg	10	12	-0.61*
	15	12	-0.11^ns
	20	12	0.03^ns
Max. width of leg	10	12	0.03^ns
	15	12	0.27^ns
	20	12	0.09^ns
Width of leg from medial splitting surface	10	12	0.08^ns
	15	12	0.23^ns
	20	12	0.15^ns
ns = Not significant; * P<0.05; P<0.01; * P<0.001

The results tend to suggest that as the slaughter weight increased each of the measurements also increased. The regression coefficients also indicate that the width of chest increased at a slower rate than the other traits in both breeds (Table 7). Apart from the height at withers and the height at pelvis in which the RS had relatively higher regression coefficients, other traits had close regression coefficients for both breeds. This was probably because the RS being the taller of the two breeds, experienced height increase at a faster rate than the WAD.

Table 7. Regression equation (y = a + bx) for body measurements on slaughter weight
Trait	Breed	Sample size	Intercept	Regression coefficient	SE¹
Height at withers	WAD	18	-40.48	6.42	0.05
Height at withers	RS	18	-40.78	8.08	0.05
Height at pelvis	WAD	18	-93.17	2.97	0.01
Height at pelvis	RS	18	-161.03	10.54	0.12
Width of pelvis	WAD	18	-84.59	2.99	0.02
Width of pelvis	RS	18	-67.15	2.92	0.07
Depth of chest	WAD	18	-133.14	10.28	0.17
Depth of chest	RS	18	-173.08	11.43	0.18
Chest girth	WAD	18	-84.77	9.35	0.02
Chest girth	RS	18	-60.71	8.43	0.08
Width of chest	WAD	18	-24.28	0.71	0.01
Width of chest	RS	18	-23.72	0.82	0.01
¹Standard error

Conclusion

It was observed that breed, sex and body weight did influence body and carcass linear measurements as well as other traits to various degrees in goats. Most of these measurements are at one stage of growth or the other highly correlated with either the empty body weight or dressing percentage.

References

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Body and carcass linear measurements of goats slaughtered at different weights

S Attah*, A O Okubanjo, A B Omojola and A O K Adesehinwa**

Abstract

Introduction

Materials and methods

Determined Analysis

Results and discussion

Variable

Variable

Variable

Weight, kg

Sample size

Height at withers

Height at withers

Conclusion

References