Comparison of carcass characteristics of Borana and Arsi-Bale goats under different durations of feedlot management

Hailu Dadi, Tatek Woldu and Tesfaye Lema

Adami Tulu Agricultural Research Center,
PO Pox 35, Ziway, Ethiopia,
edenhailu@yahoo.com

Abtract

The objective of this study was to assess the carcass characteristics of two goat breed types under different durations of feedlot management. Forty eight yearling intact male Borana (n=24) and Arsi-Bale (n=24) goats were used in a 2 x 3 factorial arrangement, the factors being breed-type (Borana and Arsi-bale) and feeding days (90, 120 and 150). The goats were slaughtered after 18 hours fasting to evaluate the various carcass traits. The carcasses were separated into leg, lion, rack, shoulder and neck and breast and shank primal cuts.

The Borana goats possessed heavier live weight, empty body weight, carcass weight and length than the Arsi-Bale goats in the feedlot environment. Dressing percentage varied from 41.0 to 45.9% for both goat breed types. Borana had greater rib eye area than Arsi-Bale goats for 120 (42.9±3.99) and 150 (47.3±1.28) feeding days. Back fat thickness was higher for both breed-types for 150 days feedlot feeding.  The highest bone proportion was 30.9% for Arsi-Bale goats while the lowest was 25.7% for Borana goats. The percentage of rack fat of Borana was higher than for the Arsi-Bale goats.

Key words: Arsi-Bale goats, Borana goats, carcass characteristics, feeding durations

Introduction

In Ethiopia, goats are kept mainly for meat, although milk production may be practiced by resource poor farmers. The estimated goat population is larger than the population of sheep under pastoral and agro-pastoral production systems (Workneh and Rowlands 2004). The number per se may not sufficiently contribute to the economic growth of the country unless productivity is substantially improved. Improvement of productivity is fundamentally based on careful performance evaluations of the genetic potential of the indigenous goat breed-types and designing  appropriate improvement of breeding methods (Wiener 1994; Bourdon  2000; Jansen and Burg Kees 2002).

Goat meat evaluations have received little attention and as a result knowledge of yield and quality of goat meat is limited when compared to sheep and cattle (Warmington and Kirton 1990; Anous and Mourad 1993). Nevertheless, this situation is changing because of increase in demand for goat meat. Thus, to be profitable and satisfy market demands further performance evaluation of carcass traits and improvement is required.

The majority of goats in the Central and Southern environments of Ethiopia are Arsi-Bale and Borana ecotypes. They are small to medium in body size. Although, farmers usually fatten these animals under different durations of feeding, genetic variations in carcass traits have been not well characterized and documented. The objective of this study was, therefore, to assess the genetic potential of Borana and Arsi-Bale goats for their carcass characteristics under different durations of a feedlot management system.

Materials and methods

Study area

The study was conducted at Adami Tullu Agricultural Research Center (ATARC) situated at a latitude of 7⁰ 9'N and 38⁰ 7^'E longitude in the semi-arid middle rift valley of Ethiopia. The altitude is 1650 masl. The soil is fine sandy loam with sand silt and clay in the proportion of 34, 48 and 18%, respectively (ATARC 1998). The area is mainly dominated by pennesitum, cinchrus grass species, forbs and acacia trees.

Animals and management

Two goat breed-types (Borana and Arsi-Bale) were used for the carcass comparison study. Forty eight yearling intact male goats were purchased from local markets in 2004. Dentition was used and also farmers were consulted to purchase goats which were about 12 months age. Borana (n=24) and Arsi-Bale goats (n=24) were assigned randomly to three feeding durations (90, 120 and 150 days), in a 2 x 3 factorial arrangement, with 8 animals per feeding duration. The animals were supplemented gradually up to 600g concentrate/head/day. The composition of the concentrate feed was 50% noug cake, 49% wheat bran and 1% salt. Grass hay, fresh lablab and tree legumes were also provided to the goats.

Slaughter and data collection

The goats were fastened for 18 hours and weighed. All eight goats were slaughtered for each feeding duration at the  ATARC animal slaughter house. Empty body weight was calculated by deducting weight of digesta from live weight. Dressing percentage of the carcass was calculated based on fasting body weight and empty body weight. Carcass length was measured from the point of the hock to the point of the neck. Leg circumference was measured across the stifle area of the legs. Kidney, scrotal, pelvic, and heart fat weight measurements were taken by sensitive balance.

The carcasses were separated into five primal cuts namely, leg, lion, rack, shoulder and neck and breast and shank. After splitting into primal cuts, these were chilled at -2C⁰ for 24 hours and after weighting each primal cut they were separated into lean meat, bone and subcutaneous fat. Rib eye area and fat thickness were measured between the 12^th and 13^th ribs. To measure rib eye area calibrated water proof paper was used. Fat thickness was measured by using a ruler at the mid point of  the 12^th and 13^th ribs. 

Statistical analysis

Data analysis were performed using the Statistical Analysis System (SAS 1999-2000), in a 2 x 3 factorial arrangement with breed-type (Borana and Arsi-Bale) and feeding duration (90, 120 and 150 feeding days) as main effects. The interaction was not significant for breed types and feeding duration. Estimated least squares means were separated by Duncan's Multiple Range Test at P< 0.05.

Results and discussion

The higher final live weight, carcass weight and carcass length for Borana compared to Arsi-Bale goats (Table 1) can be explained by the superior growth rate of Borana than the Arsi-Bale goats. Dressing percentages of Borana were higher after 150 days than for Arsi-Bale goats. The estimated dressing percentages for both Borana and Arsi-Bale goats correspond with the reports of Nsoso et al (2004) and Warmington and Kirton (1990). The Borana goats possessed greater (P<0.05) leg circumference for 120 and 150 feeding days than their counterpart. The Borana had higher (P<0.05) rib eye area than the Arsi-Bale goats for 120 (42.87±3.99) and 150 (47.31±1.28) feeding days. Back fat thickness in the present study for both breed-types was in the range of 10.00±-3±0.09 mm. Carcass from 150 feeding days of Borana had significantly (P<0.05) higher fat thickness. Oman et al (1999) reported for Bore x Spanish and Spanish goats an unadjusted fat thickness of 12 and 7 mm, respectively. As it was expected, the present study suggested that these breed-types possessed thin fat thickness and perhaps it is a characteristic feature of goat carcass. The Borana goats deposited larger (P<0.0) scrotal (114.38±0.01g) and pelvic (136.13±0.02g) fat for 120 and 150 feeding days than the Arsi-Bale goats. Heart fat accumulation was significantly (P<0.05) higher for Borana than in Arsi-Bale goats. In general, the trends for internal fat accumulation showed that increasing duration of feeding days increased fat deposition. In fact, internal fat content increased as age of the animal is advanced.

Although slight variations were observed, bone percentage was not significantly different (P>0.05) for feeding days within breed-type. The Arsi-Bale goats bone proportions were considerably (P<0.05) higher than the Borana for 120 and 150 feeding days. The proportions of bone vary from 25.7-30.9% for both breed-types. This is in agreement with the reports of Fonseca (1987) for Chernequiera goats and Ash and Norton (1987) for Australian Feral goats, but higher than Fehr et al (1976) for carcass weight ranged from 8-13 for Alpine goats. Lean meat percentages of Arsi-Bale goats were not influenced by duration of feeding, however meat percentage of Borana for 120 feeding days were significantly P<0.05) higher than 150 feeding days of Borana. In general, lean meat percentage varies from 63-67.4% and this is in agreement with the findings of Fehr et al (1976). Fat proportion gradually increased for both Borana and Arsi-Bale goats with increasing of feeding days. Fat percentages of 5.1-7.1% were reported by Fehr et al (1976) for Alpine goats.

Least squares means of carcass components for goats within breed-type and durations of feeding are presented in Table 2. The estimated means of lean meat from legs did not significantly (P>0.05) vary. The Borana had a lower (P<0.05) percentage of bone from the legs than the Arsi-Bale fed for 90 and 150 days. Compared to Arsi-Bale, higher (P<0.05) fat percentage was observed for Borana fed for 150 days. The percentages of loin cut carcass components were not significantly (P>0.05) different. This trend was also observed for percentages of meat and bone components of rack. Nevertheless, rack fat percentages for Borana was significantly (P<0.05) higher than the Arsi-Bale goats. Feedlot feeding of goats for 150 days resulted in lower (P<0.05) percentages lean meat from the shoulder and neck. Bone percentages of Shoulder and neck for Arsi-Bale goats were significantly higher (P<0.05) than the Borana goats for 90 and 150 feeding days. Fat percentage of 150 feeding days for Borana was significantly (P<0.05) higher than others feeding durations. Fat obtained from 150 feedlot feeding from Shoulder and neck for Borana had a higher (p<0.05) fat percentage than 90 and 120 feedlot feeding of Borana, the same differences were also observed for Arsi-Bale.

Breast and shank meat of Borana goats fed for 150 days possessed lower (P<0.05) percentage of meat than all others feedlot feedings. On the contrary, fat produced by 150 feeding days of Borana from breast and shank were significantly (P<0.05) higher than others feedlot feedings.

Conclusion

• Duration of feeding was found to influence live weight and carcass characteristics of both Borana and Arsi-Bale goats.

• The Borana goats produced higher live weight, carcass weight, and carcass length than the Arsi-Bale goats.

• The better performance of Borana is mainly attributed to the inherent high growth rate of this breed-type.

• The advantage of Borana goats is primarily in the higher live and carcass weights at a similar age for Arsi-Bale.

• Increasing feeding days linearly increased fat proportion while this was not true for meat and bone proportion.

• The Borana goats had a better trend for fat deposition in the carcasses compared to Arsi-Bale goats.

Acknowledgment

The authors are grateful to Merga Wakijira and Jarso Wakayo, Meseret Tilaye and Meseret Terefe for their data collection and typing the manuscript. We are also thankful to the Oromiya Agricultural Research Institute for funding this study.

References

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Received 1 December 2004; Accepted 25 November 2005; Published 1 December 2005

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