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FACTORS AFFECTING GOAT CARCASS YIELD AND QUALITY

By: "Frank Pinkerton"
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Introduction

Carcasses of meat animals are generally evaluated commercially in terms of yield and quality of lean. In beef carcasses, yield refers to the percentage of closely trimmed, boneless retail cuts (edible lean) on a carcass weight basis. Quality of lean refers to the palatability (taste appeal) of the lean and is perceived as being strongly influenced by the degree of marbling (intramuscular fat deposition). Since most goat carcasses are not presently marketed in typical retail cuts and since goat meat is primarily valued for its unmarbled lean, this evaluation scheme seems somewhat inappropriate for goats, at least for now.

Instead, goat processors seem to pay particular attention to dressing percent and to "muscling" or "meatiness", both terms reflecting an assessment of meat-to-bone ratios. However, processors do prefer young goats (less than 40 lb live weight) to show considerable fat deposition around the kidneys and heart. Experienced goat buyers are quite adept at palpating the loin/rib area of a live kid and predicting degree of muscling and kidney fat and, accordingly, the visual and commercial appeal of the carcass to buyers. Contrarily, older, heavier carcasses are discriminated against if they have more than a (poorly defined) minimum of fatness.

Carcass Characteristics

The dressing percentage of slaughter goats may be influenced by age, weight, sex, body condition, amount of gut fill at slaughter, whether the carcass is weighed hot or cold and, of course, by the number of body components included in the yield calculation. Dividing the unshrunk liveweight into the weight of the hot carcass with liver, heart and kidney but without skin, head, feet and viscera will yield dressing percent values in the 45-52% range. The interactions among the individual factors affecting dressing percentage are great, making it rather difficult to accurately predict carcass yield or quality by visual examination of the live goat.

Table 1, taken from a review by Shelton, Snowder and Figueiredo (1984), compares slaughter characteristics of castrated vs. intact meat type kids (columns 1 and 2, 4 and 5), Angora vs. meat type intact males (columns 3 and 4) and aged Angora females vs. aged meat type females (columns 6 and 7); column 8 shows the averages for the 92 head in the study. Table 1 also indicates the percent of the live weight found in the hanging carcass (with kidneys) and in various body components. Certain of these components are considered to be edible by various groups of consumers; any calculation of "dressing percent" would necessarily have to denote which component is to be included.

The effects of castration are also shown in Tables 2 and 3 (Shelton, Snowder and Figueiredo, 1984). These and other studies indicate that intact males are heavier per day of age, make more efficient gains but have a higher percent of their weight in the lower value hindquarters. Castrates show more carcass quality (improved fat cover) and generally sell for more per lb, except in specialized markets taking larger, more mature bucks. Castration may have an adverse impact on daily gain as documented in Table 2.

The effect of breed on carcass characteristics of goats has not been extensively reported. The recent arrival of the meat type Boer goat has sparked much interest in its potential for crossing with dairy and Spanish goats. Table 4 reports a study in England which compares two dairy breeds, Saanen and Nubian, with Boer x Saanen goats, all slaughtered at various body weights (Gibb, Cook & Tresher, 1993). All were on a hay and concentrate ration after weaning at 8 weeks of age. The numbers of animals used were quite small and so apparently was the genetic diversity within breed; readers should be aware of these experimental limitations.

In this study there were no significant differences between breeds in 8 week weights or in daily feed intake. With regard to daily weight gains, at heavier slaughter weights, the Saanen kids were superior to the Boer x Saanen crosses which, in turn, were superior to the Nubian kids. Nubian and, to a lesser extent, Boer x Saanen crosses produced superior carcasses in terms of muscling. The Boer x Saanen crosses had more fat overall all slaughter weight than the Nubian kids; Saanen kids had the least fat.

The energy density of diets fed to goats can influence carcass characteristics across various slaughter weights. Table 5 illustrates this point using Boer goats in South Africa (Ueckerman, 1969). Dressing percent rises with slaughter weight and length of time on feed. Feed efficiency (lb of feed required to put on lb of gain) decreases as heavier carcasses are produced. An all-roughage ration required more time on feed and required more lb of hay per lb of gain than the rations containing concentrates. Apparently, the responses to 60:40 R:C and 40:60 R:C ratios were rather similar. The relative costs of hays and concentrates and reduced time on feed at the higher concentrate level would determine the economic choice among R:C ratios.

Conclusions

Table 1
Carcass characteristics of slaughter goats may be affected by a number of genetic and environmental conditions as well as specific herd management decisions.

Muscling, not body fat, is the most important goat carcass characteristic.

The goat industry could likely benefit from the creation of a set of grade standards somewhat similar to those now used by the sheep and lamb trade.

Table 2. Results of Castration of Meat Type Male Kid Goats.


Treatment




No.



Initial Wt., lb



Gain

lb2



Condition

Score3
Sale Price4

(1984)

US $ Per Head
Intact Males
46
43.3
16.1
3.5
15.75
Castrated by Knife
48
42.5
15.1
3.9
17.00
Castrated by Burdizzo1
48
42.6
14.8
3.9
18.00
1 One kid died after castration by burdizzo and four showed signs of improper or incomplete castration.

2 Weight gains following 103 days on pasture.

3 Condition scores were assigned on a 1-6 basis, with the high values being fatter.

4 Twelve (12) animals were randomly kept from each group of slaughter and the remainder were sold at a local auction. The prices shown are that received for the remaining animals which were sold.

Table 3. Slaughter data from castrate vs. intact males.

Treatment



No.
Slaughter Wt.
Hide Wt.
Carcass Wt.
Dressing %
Backfat Thickness
Ribeye Area
---------------- lbs-------------
---- in----
- sq. in -
Intact Males
12
60.7
7.7
27.5
45.3
0.003
4.47
Castrates
24
54.1
6.2
24.6
45.5
0.100
3.97

Table 5. Meat Production and Carcass Yields in Boer Goats.
Roughage:Concentrate Ratio
100:0
60:40
40:60
Slaughter Wt., lbs
70.0
100.1
70.0
100.1
70
100.1
Number of goats
231
336
182
308
168
301
Weeks to slaughter
33
48
26
44
24
43
Feed to gain ratio
10.3
13.3
8.1
9.5
8.6
9.5
Average daily gain, lb
.27
.27
.34
.30
.37
.31
Dressing percent
49.4
52.4
51.8
56.3
54.6
56.5

References

Gibb, J.J., J. E. Cook, and T. T. Tresher, 1993. Performance of British Saanen, Boer X British Saanen and Anglo-Nubian Castrated Male Kids from 8 weeks to Slaughter at 38,33 or 38 kg liveweight. Anim. Prod. 57:263-271.

Shelton, Maurice, Gary Snowder, and E.A.P. Figueiredo, 1984. Meat Production and Carcass Characteristics of the Goat. USAID Title XII. Small Ruminant Collaborative Research Support Program, Texas A & M University, San Angelo.

Ueckerman, L., 1969. Master of Science Ag. Thesis, University Pretoria, Republic of South Africa.

About the author: No information about this authour is currently available.

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