Submitted to: Growth in Ruminants Symposium
Publication Type: Proceedings
Publication Acceptance Date: August 20, 1998
Publication Date: N/A
Interpretive Summary: Historically, fats and fatty acids have been an important dietary management factor for animal production, particularly for adding energy to animal diets and for adding essential fatty acids to non-ruminant diets. Non-nutrient substances such as hormones and antibiotics have been studied and(or) utilized since the 1950's as growth enhancers. Research is reviewed with emphasis on beef cattle, regarding the influence of dietary fatty acids and oil and of exogenous growth enhancers on specific tissue growth. Both the pituitary and thyroid glands are involved in determining the biological effects of feeding fatty acids and oils and of treatments with estrogenic growth promoters, somatotropin, and chlortetracycline. This paper suggests research opportunities for refining management strategies to further improve cattle production efficiency and(or) product composition.
Research is reviewed with emphasis on beef cattle, regarding the influence of dietary fatty acids and oil and of exogenous growth enhancers on specific tissue growth. Results identify two areas of research for improving our understanding of the potential roles of fats and fatty acids in cattle production. Caprylic and myristic acids appear to enhance the metabolism of thyroxine to triiodothyronine, suggesting influences of specific fatty acids or type of oil on thermogenesis and metabolic rate. Feeding oil seeds such as roasted soybeans in place of soybean meal appears to attenuate the sensitivity to thyrotropin releasing hormone and growth hormone releasing hormone. Estrogen treatment enhances the pituitary sensitivity to releasing hormones for the release of thyroid stimulating hormone, suggesting this is a factor involved in the growth enhancement effects of estrogens in cattle. Estrogens do not appear to affect pituitary sensitivity for the release of growth hormone. This suggests a mechanism of action for estrogens unrelated to a direct effect on growth hormone release, and is consistent with the concept of additivity of the effects observed for estrogen and growth hormone treatments on protein accretion in cattle. Growth hormone treatment is effective in enhancing carcass protein accretion in young growing cattle. The antibiotic chlortetracycline appears to attenuate the pituitary release of both growth hormone and thyroid stimulating hormone and tends to promote greater fat accretion in growing/finishing cattle. This paper suggests research opportunities for refining management strategies to further improve cattle production efficiency and(or) product composition.