Optimizing carcass value and the use of anabolic implants in beef cattle

ABSTRACT The historical use of implants in ruminants dates to 1947 with the first implanting of Hereford heifers with diethylstilbestrol. Since that time, several different implants have been developed with varying degrees of commercial success. It is recognized that the use of anabolic implants in beef cattle offers the greatest return on investment outside of ensuring adequate nutrition. Although this may be true with respect to increased weight gain and improved feed efficiency, the influence of anabolic implants on carcass characteristics has not all been positive. Since the early use of diethylstilbestrol, packers have been concerned about the influences of implants on meat tenderness and carcass value as indicated by quality grade. This concern has been renewed and amplified with the increased use of anabolic implants and the introduction of combination implants. Estrogenic, trenbolone acetate, and combination implants used today have been shown to increase live performance, rate of empty body protein gain, carcass weight, ribeye area, and closely trimmed boxed beef weights. The use of anabolic implants has resulted in varying decreases in marbling score and infrequent increases in skeletal maturity of carcasses, thus decreasing the proportion of carcasses grading Choice. Factors not commonly measured can influence marbling score. Moreover, the inherent variation in intramuscular fat distribution along the loin should be considered in determining influences of implants on marbling score and(or) quality grade. An increased proportion of dark cutters and in Warner-Bratzler shear force values have occasionally been reported in combination with the use of anabolic implants. It should be noted that these results are limited and need to be treated with caution due to the large number of extraneous factors that can affect the proportion of dark cutters at slaughter and decreased tenderness after chilling. Implant strategies are available to alleviate concerns with carcass quality and their final value.

Implications

With 24 different anabolic implants available, opportunities are available for producers to target a particular end response. In steers, combination implants have been shown to improve feeding performance while having only minor influence on reducing carcass or meat quality. The use of estrogen-based implants is less likely to increase feeding performance and may not adversely affect measures of meat quality. In heifers, a single dose of an estrogen-based implant does not seem to improve feeding performance and has decreased carcass quality grade. Androgen-based and combination implants result in the greatest increase in feeding performance of heifers and may have little influence on carcass quality. Limited data suggest that finishing implanted cattle to an empty body fat or carcass fat-endpoint similar to nonimplanted cattle may diminish or alleviate decreases in quality grade. Some studies have shown that the use of implants injudiciously will most likely result in reduced marbling scores and decreased tenderness. Implant strategies are available to minimize these effects.

Key Words: Carcass Quality, Cattle, Composition, Growth, Implantation

© 2001, by the American Society of Animal Science. All rights reserved.

J. Anim. Sci. 2001. 79:E296-E306