Growth and Carcass Characteristics of Spanish,

¼ and ½ Boer Wethers After 66 Days on Feed

Cooperators:

Ferrell Davis and Bob Duke

4D Ranch - Utopia, TX

Rodney Robinson

Rancho Pegaso - Kerrville, TX

Dr. Rick Machen, Asst. Prof. & Extension Livestock Specialist, Uvalde

Eddie R. Holland, Kerr CEA-AG, Kerrville

L. Warren Thigpen, Jr., Bandera CEA-AG, Bandera

Kenneth G. White, Uvalde CEA-AG, Uvalde

Bandera County

SUMMARY

Rate of gain and feed efficiency were measured during a 66 day feeding trial involving 150 meat goat wethers (Spanish, ¼ Boer and ½ Boer; 50 each). Rate of gain was directly related to percentage Boer; mean average daily gain (lb/hd/day) for the breed groups were .25, .33 and .49 for the Spanish, ¼ and ½ Boer, respectively. Feed efficiency (lb feed/lb gain) did not differ significantly between the Boer influenced groups (8.2 and 8.3 for ¼ and ½, respectively). When compared to the Spanish wethers, Boer influenced kids were 29% more efficient. On a live weight basis, ½ Boer wethers produced heavier carcasses with larger loineye areas. However, when compared on a per pound of carcass weight basis, carcass measurements did not differ across the three groups.

PROBLEM

Excitement, enthusiasm and interest in meat goat production, marketing and consumption exploded with the introduction of the Boer goat to the United States in 1993. Developed in South Africa and now spread throughout the world, the Boer goat can potentially contribute several beneficial characteristics to a meat goat production system: docility, aggressive eating behavior and rapid growth potential. Due to limited numbers of purebred animals and their relatively high value, studies to date have involved evaluation of the Boer in crossbreeding programs with Angora and Spanish does.

Relatively few studies have compared the performance of Boer-influenced and Spanish goats under feedlot conditions. In addition, studies published to date have been limited to ½ Boer influence.

OBJECTIVE

The objective of this study is to 1) compare the average daily gain and feed efficiency of Spanish, ¼ and ½ Boer goats under feedlot conditions and 2) to evaluate the carcass characteristics of these goats after the feeding period.

MATERIALS/METHODS

Spring-born Spanish, ¼ and ½ Boer wether kids (n=50 per group) were selected by weight postweaning and fed in breed groups (1 pen per group) for 66 days to evaluate feedlot performance and carcass characteristics. Wethers were selected such that average initial weight would be near 50 pounds. The ¼ Boer (½ Boer bucks bred to Spanish does) and ½ Boer (purebred Boer bucks on Spanish does) wethers were reared from the same flock of Spanish does on one ranch. The Spanish wethers, well above average quality, were selected from another flock by weight to match the ½ Boer wethers.

Wethers were self fed a commercially available, 14% crude protein alfalfa-based pellet containing approximately 60% TDN. A preliminary adjustment period of ten days (10/10 to 10/23/95) preceded initiation of the trial. Goats were held off feed and water overnight before each weighing. During the preliminary period, all goats were treated for internal parasites and vaccinated against Clostridium perfringens type C & D and tetanus.

Upon completion of the feeding period, 10% (n=5) head per treatment were transported to a nearby slaughter facility for carcass data collection. The five goats nearest the average liveweight for each breed group were selected for slaughter. All goats were slaughtered the same day. Hot carcass weights were obtained on the kill floor. Carcass data was collected 96 hours later and included chilled carcass weight, loineye area and kidney and pelvic fat content.

RESULTS/DISCUSSION

Rate of Gain & Feed Efficiency

One Spanish wether died (cause undetermined). Seven Spanish wethers were removed from the study after 34 days on feed due to health problems and weight loss. The ¼ Boer kids were approximately one month younger than either of the other two groups and consequently, weighed less at the start of the feeding period (Table 1). The heaviest ¼ Boer kids available were used. Average daily gain was positively related to Boer influence (Table 7) and significantly different between the three groups (P<.01).

While rate of gain is important, feed efficiency is an equally important characteristic. The previously mentioned aggressive eating behavior of the Boer is demonstrated in Table 1. As indicated, when feed consumption is expressed as a percentage of body weight, the Boer- sired kids exhibited greater feed consumption. Likewise, because they also gained at a faster rate, the Boer-sired kids more efficiently converted feed to gain (8.2, 8.3 and 10.8 for ¼, ½ and Spanish, respectively). The higher feed consumption exhibited by the ½ Boer relative to the other kids is inconsistent with the results of a previous study reported by Waldron et al., 1995. Therefore, conclusions about feed consumption differences due to breed of sire is an area that needs further research.

Feed cost of gain is another economically important factor to consider. Facilities limited the number of feed groups to three. Since wethers were fed as breed groups, statistical analysis of the feed efficiency data was precluded. Given a feed cost of $185 per ton delivered to the producer, a market value of 75¢ per pound (liveweight) and considering the feed conversions shown above, it appears that feed cost of gain came near breakeven (market value $0.75-.80 per pound liveweight) for the Boer sired wethers ($0.76 and $0.79) but was not economically feasible for the Spanish wethers ($1.00 per pound of gain). This economic analysis refers only to feed cost of gain and does not provide for a return to overhead, management or interest.

It should also be noted that feed costs were at a 3-4 year high during this trial. In addition, had the energy content of the ration been higher, feed efficiency may have been more favorable. Less expensive feed ingredients and a more efficient feed conversion could substantially improve the economic feasibility of feeding meat goats.

Carcass Characteristics

Goats were scheduled for slaughter near the end of the year. Live weight of the goats upon completion of the study (>60 lb) precluded the slaughter of large numbers. (A logistical problem involved location of a packer capable of slaughtering goats and merchandising carcasses weighing in excess of 30 pounds. Therefore, slaughter numbers were restricted.

Data from this small group of goats is presented in Table 2. Dressing percent was calculated using hot carcass weight and live weight at slaughter (goats were held off feed and water overnight prior to slaughter). A weekend and a holiday fell between slaughter and carcass fabrication, therefore chilled carcass weights were recorded 96 hr post-slaughter. Cooler shrink was calculated as the difference between hot and chilled carcass weights, expressed as a percent of hot weight. Carcasses were separated between the 12 and 13 rib for fat thickness and loineye measurements. Loineye area data represent the average of two independent evaluators. Kidney and pelvic fat was removed at fabrication and includes the kidneys.

Results of this study concur with those of the Waldron et al. 1995. Boer sired kids grew faster and produced more marketable product when compared to Spanish at a constant age. However, when compared on a constant carcass weight basis, differences between breed groups were near zero. All carcasses were essentially devoid of subcutaneous fat over the loineye at the 12th rib, therefore, fat thickness was not recorded. However, a significant portion of the carcass weight, up to 6%, was internal fat.

Although the 96 hour interval between slaughter and fabrication is not typical for most packers, it does point to a handling difference between goat and lamb, beef or pork carcasses. Unlike the other species, the goat has very little subcutaneous fat and therefore has little or no protection from desiccation. therefore, if goat meat is to be shipped significant distances, it must be protected from dehydration (i.e. fabricated into wholesale cuts and vacuum packaged).

CONCLUSIONS

What impact the Boer goat will have on the meat goat industry will ultimately be a function of its ability to produce a profit. The postweaning data from this and other studies demonstrate that, when nutrition is not a limiting factor, the Boer-sired kids did gain faster.

Perhaps the greatest benefit of using Boer sires, relative to Spanish, is increased growth potential of the Boer-cross kids. The carcass data from this and other studies suggest that there are little or no compositional differences attributable to breed of sire when goats of similar liveweight or similar carcass weight are compared.

Growth and carcass evaluation studies to date have been confined to kids with ½ Boer influence or less. Subsequent studies involving larger percentages and purebreds will further quantitate the contribution of the Boer to the U.S. meat goat industry.

References

Waldron, D.F., J.E. Huston, P. Thompson, T.D. Willingham, J.S. Oman and J.W. Savell. 1995. Growth rate, feed consumption and carcass measurements of Spanish and BoerxSpanish goats. J. Anim. Sci. 73, Suppl. 1:253

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