Cattle temperament influences metabolism: 2. Metabolic response to an insulin sensivitiy test in beef steers

Authors: Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; Broadway, Paul; HUGHES, HEATHER - West Texas A & M University; ROBERTS, SHELBY - West Texas A & M University; RICHESON, JOHN - West Texas A & M University; SCHMIDT, TY - University Of Nebraska; VANN, RHONDA - Mississippi State University

Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2016
Publication Date: 4/1/2016
Citation: Sanchez, N.C., Carroll, J.A., Broadway, P.R., Hughes, H.D., Roberts, S.L., Richeson, J.T., Schmidt, T.B., Vann, R.C. 2016. Cattle temperament influences metabolism: 2. Metabolic response to an insulin sensivitiy test in beef steers. Domestic Animal Endocrinology. 56:85-95.

Interpretive Summary: Cattle temperament, defined as the reactivity of cattle to humans or new environments, can greatly influence several physiological systems in the body, including immunity, stress, and most recently discovered, metabolism. Greater circulating concentrations of non-esterified fatty acids found in temperamental cattle suggests that temperamental cattle are metabolically different than calm cattle. Further, elevated non-esterified fatty acid concentrations have been reported to influence insulin sensitivity. Therefore, the objective of this study was to determine whether cattle temperament would influence the metabolic response to an insulin sensitivity test. The results from this study demonstrate that distinct differences in metabolic responsiveness are present between calm and temperamental cattle. Specifically, greater insulin concentrations were observed in temperamental cattle, as well as elevated non-esterified fatty acids, and decreased blood urea nitrogen and insulin sensitivity. Further research is necessary to determine the mechanisms that ultimately result in elevated NEFA concentrations and decreased insulin sensitivity in Temperamental cattle in order to more fully understand the effect of temperament on metabolism.

Technical Abstract: Cattle temperament, defined as the reactivity of cattle to humans or novel environments, can greatly influence several physiological systems in the body, including immunity, stress, and most recently discovered, metabolism. Greater circulating concentrations of non-esterified fatty acids (NEFAs) found in Temperamental cattle suggests that Temperamental cattle are metabolically different than Calm cattle. Further, elevated NEFA concentrations have been reported to influence insulin sensitivity. Therefore, the objective of this study was to determine whether cattle temperament would influence the metabolic response to an insulin sensitivity test (IST). Angus-cross steers (16 Calm and 15 Temperamental; 216 +/- 6 kg body weight) were selected based on Temperament Score measured at weaning. On day 1, steers were moved into indoor stanchions to allow measurement of individual ad libitum feed intake. On day 6, steers were fitted with indwelling rectal temperature probes and jugular catheters. At 2 pm on day 7, steers received the IST (2.5 international units of bovine insulin/kg body weight). Blood samples were collected and serum isolated at 10, 15 and 30-min intervals from -60 to 150 min relative to the IST. Serum was stored at -80C until analyzed for cortisol, glucose, NEFA, and blood urea nitrogen (BUN) concentrations. All variables changed over time (P < 0.01). For the duration of the study, Temperamental steers maintained greater (P < 0.01) NEFA and decreased (P = 0.01) BUN and insulin sensitivity (calculated using RQUICKI) compared to Calm steers. During the IST, Temperamental steers had less (P = 0.04) glucose, greater (P < 0.01) insulin, and a greater (P < 0.01) insulin:glucose as compared to Calm steers. These data suggest that Temperamental cattle have an altered metabolic response to an IST, which may influence other metabolic and physiological responses in the body.