Manipulation of Endogenous and Exogenous Hormones for Red Meat Production

Abstract

SummaryGrowth and development of domestic livestock for red meat production are often discussed in the context of environmental factors, nutritional requirements, genetic potential and the anabolic agents affecting production efficiency. In this minireview, the effects of endogenous and exogenous hormones on animal growth are reviewed. The pituitary, pancreatic and gonadal hormones known to affect growth and(or) carcass composition are cited to illustrate and place into perspective the important contributions that the endocrine system makes to animal production. Manipulation of endogenous hormones through 1) administration of synthetic releasing and inhibiting peptides and 2) immunoneutralization techniques, will likely provide the livestock producer with new technological approaches for increasing red meat production. Researchers continue to evaluate the efficacy of natural and synthetic steroids, and combinations thereof, as suitable anabolic agents. In conclusion, several hormones of both endogenous and exogenous origin can be manipulated to improve or enhance growth and development of the meat-producing animal.

Growth and Carcass Traits of Heifers as Affected by Hormonal Treatment

“…Heitzman and Chan (1974) and Galbraith (1980) reported greater nitrogen retention and a decrease in plasma albumin in TBA-treated heifers. Schanbacher (1984) observed that immunizing intact males against estradiol increased rib-eye areas and fat thickness. In contrast, Wise and Ferrell (1984) observed no differences in water, fat or protein content between BSA-E and C heifers.…”

“…Wise and Ferrell (1984) observed that BSA-E heifers had increased feed efficiency as compared with control heifers. Schanbacher (1984) reported that immunoneutralization provides a simple, non-invasive approach to endogenous hormone deprivation. Both active and passive immunization can be used to neutralize the activity of circulating hormones.…”

Immunization of bull calves with a GnRH analogue-human serum albumin conjugate: effect of conjugate dose, type of adjuvant and booster interval on immune, endocrine, testicular and growth responses

“…Although immunization against GnRH has proved to be partially effec¬ tive, there are problems relating to consistency and longevity of the immune response both within and between animals in most studies in the literature. An optimum dose of GnRH conjugate has not been deter¬ mined in farm animals; however, doses between 0.05 and 5.00 mg GnRH conjugated to various protein carriers have been shown to elicit immune responses with varying efficiency (Schanbacher, 1984a;Falvo et ah, 1986;Goubau et ah, 1989b;Lobley et ah, 1992;Adams and Adams, 1992). Carson et ah (1992) reported that 1.0 mg of a GnRH conjugate given to prepubertal bulls (n = 2) was more effective than 4.0 mg. An optimum primary-booster interval has not been determined in any of the studies carried out to date.…”

Effect of feeding Zilpaterol hydrochloride for 20 days to calf-fed Holstein steers with a 3 or 10 day withdrawal period antemortem on carcass characteristics and tenderness

“…A study conducted by Schanbacher (1984) showed a 25.8% increase in ADG additionally Johnson et al (1996a) found an increase of 14-25% with the use of TBA-E 2 implants. In a different study, Johnson et al (1996b) showed an increase in carcass protein deposition with the use of TBA-E 2 .…”

“…However, reported that feeding ZH for 30 days resulted in loin eye muscle color that was a brighter cherry red color than the control. implanted steers when compared to non-implanted steers (Johnson et al, 1996a;Pampusch et al, 2008;Schanbacher, 1984). A combination of TBA, and E2 implants have been shown to amplify the observed effects including; feed efficiency, rate of gain, and muscle growth in cattle (Bruns et al, 2005;Eversole et al, 1989).…”