Submitted to: Journal of Animal Physiology and Animal Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2013
Publication Date: January 16, 2014
Citation: Sanchez, N.C., Carroll, J.A., Randel, R.D., Vann, R.C., Welsh Jr, T.H. 2014. Associations between endotoxin-induced metabolic changes and temperament in Brahman bulls. Journal of Animal Physiology and Animal Nutrition. 98:178-190. DOI: 10.1111/jpn.12074. Interpretive Summary: A collaborative effort between scientists at the Livestock Issues Research Unit, Texas AgriLife Research, and Mississippi State University was undertaken to determine the influence of cattle temperament on the metabolic response of Brahman calves to an endotoxin challenge. Cattle temperament is known to affect many aspects of production including reproduction and growth. Additionally, we previously demonstrated that the temperature, sickness behavior, and epinephrine responses to an endotoxin challenge differed due to temperament. As available energy can play a major role in the ability of an animal to elicit an appropriate immune response, a study was designed to determine if metabolites and metabolic hormone concentrations differed in cattle of differing temperament in response to an endotoxin challenge. Results from this study demonstrate that, indeed, temperament affects the concentrations of glucose, insulin, non-esterified fatty acids, and blood urea nitrogen. Specifically, glucose concentrations increased in calm and intermediate bulls following administration of endotoxin, but not in temperamental bulls. Additionally, insulin concentrations peak 2.9- and 2.4-fold greater in calm bulls compared to intermediate and temperamental bulls. Temperamental bulls also maintained greater non-esterified fatty acid concentrations throughout the experiment compared to calm and intermediate bulls. These data suggest inherent differences in metabolism exhist amongst bulls of differing temperament. Specifically, these data suggest that temperamental bulls utilize circulating non-esterified fatty acids as an energy source rather than glucose as in calm and intermediate bulls. The use of circulating NEFA may allow for a quicker response to increasing energy demands required during times of immunological challenge, compared to the time required to break down glycogen into glucose, which may enhance the immune response to LPS challenge. Additionally, these data provide further evidence for the need to select animals that display a more intermediate temperament, as they produce a response that is furthest from the two extremes observed by calm and temperamental bulls. This information will be of interest to scientists working in the fileds of innate immunity, metabolism, and behavior, as well as beef producers, and can be used in order to modify protocols for working with cattle of differing temperament.
Technical Abstract: The influence of temperament on the alteration of metabolic parameters in response to a lipopolysaccharide (LPS) challenge was investigated. Brahman bulls were selected for this study based on temperament score. Bulls were fitted with indwelling jugular catheters for serial sampling to evaluate peripheral blood concentrations of glucose, blood urea nitrogen (BUN), non-esterified fatty acids (NEFA), and insulin before and after LPS administration (0.5 µg/kg body weight). Pre-LPS glucose and blood urea nitrogen (BUN) did not differ among the temperament groups (Calm, Intermediate, and Temperamental). However, pre-LPS insulin was lower, whereas pre-LPS NEFA was greater in Temperamental compared to Calm and Intermediate bulls. Post-LPS glucose was increased in Calm and Intermediate bulls but not in Temperamental bulls. Post-LPS insulin increased in all bulls with peak insulin concentrations 2.9- and 2.4- fold greater in Calm than Intermediate and Temperamental bulls, respectively. Post-LPS NEFA fluctuated throughout the sampling period, with Temperamental bulls maintaining greater NEFA concentration compared to Calm and Intermediate bulls. Serum BUN increased post-LPS, with lower BUN concentration in Temperamental bulls. Collectively, these data demonstrate that animal temperament is related to the metabolic responses of Brahman bulls following a provocative endotoxin challenge. These data suggest that Temperamental bulls preferentially utilize an alternate energy source (i.e., NEFA) to a greater degree than do Calm and Intermediate bulls. The use of circulating NEFA from lipolysis may reduce the negative metabolic consequences of an immune response by allowing for a rapid response to increasing energy demands required during immunological challenge, compared to the time required for glycogenolysis and gluconeogenesis.