|Bradbury, Brook -|
|Vann, Rhonda -|
|Welsh Jr, Thomas -|
|Randel, Ronald -|
Submitted to: Beef Improvement Federation Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 10, 2012
Publication Date: April 23, 2012
Citation: Sanchez, N.C., Bradbury, B.L., Carroll, J.A., Vann, R.C., Welsh Jr, T.H., Randel, R.D. 2012. Metabolic differences in temperamental Brahman cattle can affect productivity. Proceedings of 2012 Beef Improvement Federation Annual Research Symposium, April 18-21, 2012, Houston, TX. p. 99-112. Available: http://brahman.org/PDFs/News/2012/BIFProceedings2012.pdf. Interpretive Summary: A series of collaborative studies was conducted involving scientists from the Livestock Issues Research Unit, the Texas AgriLife Research and Extension Center-Overton, Texas AgriLife Research-College Station, and Mississippi State University in order to elucidate the potential influence of temperament on metabolism in Brahman cattle. Data from these studies suggest that clear metabolic differences exist between calm and temperamental Brahman calves. Specifically, the data suggest that greater cortisol concentrations observed in the temperamental bulls may make them more resistant to cortisol, which may have reduced their subsequent glucose and insulin responsiveness. The decreased ability to utilize glucose supports the potential for temperamental cattle to utilize an alternate source of energy when glucose concentrations are low. Therefore, it is likely that temperamental cattle utilize free fatty acids, resulting from the continuous break down of adipose tissue, to fuel tissues and organs that can utilize other energy sources rather than glucose. These data go against treating "all cattle the same", as alternative management for temperamental cattle (e.g., not implanting due to the likelihood of decreased fat deposition by temperamental cattle) may decrease input costs. Future research by our research team is focused on determining if alternative management strategies for calm versus temperamental cattle can increase profitability through reducing costs. This information will be of interest to both scientists and producers working in the field of beef cattle production with a specific focus on animal behavior, stress, and immune responsiveness.
Technical Abstract: Many factors may adversely affect the growth and productivity of livestock. These include stressors associated with management practices, such as weaning, handling relative to transportation, and vaccination, that can modulate growth through the production of stress-related hormones (i.e., cortisol, epinephrine, and norepinephrine). As the cost of cattle production continues to increase, it is essential for producers to find ways to decrease input costs in order to increase profit. Temperament is an additional factor that can influence the productivity of cattle. Temperament is defined as the manner in which cattle react to humans or novel environments. Several research groups have demonstrated that temperament can negatively affect various production traits. Additionally, cattle temperament has been linked to stress responsiveness. Specifically, cattle that are more temperamental have greater circulating concentrations of the adrenal gland derived stress hormones which also markedly affect metabolism. The adrenal glucocorticoid cortisol stimulates the production of glucose from substrates such as lactate, glycerol, and amino acids (i.e., gluconeogenesis) in the liver, inhibits the uptake of glucose into adipose tissue, and continuously stimulates the breakdown of muscle protein. The adrenal catecholamine epinephrine (i.e., adrenaline) increases plasma concentration of the energy substrates glucose and non-esterified fatty acids (NEFAs) through stimulating the breakdown of glycogen, the molecule by which glucose is stored, and triglycerides. The inherently greater concentrations of metabolically active stress hormones in temperamental cattle may be the basis for how temperament affects metabolic performance during both stress-free and stressful circumstances. The interaction between temperament and metabolism is one area that has yet to be studied in sufficient detail. This paper discusses three studies aimed at elucidating the potential influence of temperament on metabolism.