Livestock Research for Rural Development 17 (12) 2005 Guidelines to authors LRRD News

Citation of this paper

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 (47.31.28) 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 12th and 13th 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 12th and 13th 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.

Table 1 least squares means of carcass yield traits and carcass composition for goats within breed-type and duration of feeding

Item

Borana

Arsi-Bale

90 days

120 days

150 days

90 Days

120 Days

150 Days

Live weight #, (LW), kg

23.38.2.14b

28.001.29a

30.631.07a

14.000.63d

17.750.58c

18.500.75c

Empty body weight*(EBW), kg

18.932.09b

22.703.25a

20.050.90a

11.220.51d

15.170.56c

15.350.63c

Carcass Weight, kg

10.511.16b

12.560.75a

13.560.52a

5.850.25d

8.150.26c

7.620.47cd

Carcass length, cm

72.851.83b

76.311.2a

78.431.61a

64.560.85d

69.251.18c

67.370.88cd

Dressing, %LW

44.570.01ab

44.680.01ab

44.260.01ab

41.930.01cb

45.970.01a

41.090.01c

Dressing %EBW

55.820.01a

55.210.01ab

54.110.00ab

52.210.01bc

53.870.00ab

49.410.01c

Leg circumference, cm

29.561.66b

33.181.0a

33.430.43a

23.680.52c

27.310.80b

27.120.76b

Rib eye area, mm2

38.386.44abc

42.873.99a

47.311.28a

23.872.71d

36.371.43bc

29.001.33cd

Back fat thickness, mm

1.400.25bc

1.410.20bc

3.000.09a

1.190.13bc

1.000.00c

1.560.11b

Kidney fat, g

62.40.02b

73.500.01b

134.500.02a

24.380.01b

35.130.01b

50.500.01b

Scrotal fat, g

33.200.01c

72.130.01b

114.380.01a

18.500.01c

33.750.01c

36.250.00c

Pelvic fat, g

65.500.01bc

81.630.02b

136.130.02a

25.000.00c

47.290.01bc

44.750.01bc

Heart fat, g

40.750.01b

49.570.00ab

58.250.01a

9.500.00d

21.250.00cd

29.000.00c

Carcass composition, %

 

 

 

 

 

 

Bone 

28.110.02ab

25.730.01b

26.360.01b

30.880.01a

29.800.01ab

30.920.01a

Lean meat

66.240.01abc

67.420.01a

63.070.01c

66.100.01abc

66.850.01ab

63.660.01bc

Fat

5.630.01bc

6.830.01b

10.560.01a

3.100.01d

4.060.01cd

5.40.01bc

Means within the row with different subscript letter differ at P<0.05.
*EBW, Empty body weight; #LW, fasting live weight.

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.

Table 2 least squares means of carcass yield components (primal cuts) for goats within breed-type and duration of feeding

Carcass components

Borana

Arsi-Bale goats

90 days

120 days

150 days

90days

120days

150days

Leg

Meat%

69.310.10a

70.300.01a

67.930.01a

68.060.01a

67.750.02a

66.440.01a

 

Bone %

27.100.02ab

25.420.01b

26.140.01b

30.00.02a

28.910.01ab

30.410.01a

 

Fat %

  3.590.01ab

  4.200.01ab

  5.930.00a

  1.940.01b

  3.320.02b

  3.140.00b

Loin

Meat%

64.500.03a

67.500.01a

62.210.03a

60.740.03a

67.380.04a

64.370.02a

 

Bone %

29.610.04a

22.900.02a

24.540.01a

30.120.02a

23.070.02a

26.990.01a

 

Fat %

  5.890.01a

  9.600.01a

13.250.02a

  9.120.05a

  9.530.05a

  8.600.01a

Rack

Meat%

54.790.06a

60.890.01a

56.790.02a

63.330.01a

63.960.02a

56.050.03a

 

Bone %

35.860.01a

31.990.01a

30.870.01a

33.490.01a

33.890.04a

38.460.02a

 

Fat %

  9.350.03ab

  7.110.01b

12.330.02a

  3.160.01c

  2.140.01c

  5.180.01c

Shoulder and neck

Meat%

68.610.01a

69.590.01a

64.240.01b

68.790.01a

68.250.01a

63.420.02b

Bone %

25.960.02bc

25.200.01c

26.010.01bc

29.740.01a

28.940.01ab

30.490.01a

 

Fat %

  5.410.01b

  5.230.01b

  9.750.01a

  1.450.00c

  2.790.00c

  6.080.00b

Breast and Shank

Meat%

64.470.03a

61.780.02a

56.350.01b

61.690.02a

64.920.01a

62.190.02a

Bone %

28.520.03b

25.400.02b

25.84001b

34.560.02a

30.280.02ab

30.530.01ab

Fat %

  6.990.02c

12.800.01b

17.800.01a

  3.730.01c

  4.780.01c

  7.270.01c

Means within the row with different subscript letter differ at P<0.05

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


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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