Cattle Temperament Alters the Metabolic Response to a Feed Restriction Challenge in Beef Steers
Published on: 2018-08-27
Recent studies have demonstrated metabolic differences between calm and temperamental cattle. Specifically, temperamental cattle exhibit greater concentrations of NEFAs, decreased blood urea nitrogen (BUN), and decreased insulin sensitivity compared to Calm cattle. It is hypothesized that these differences may influence the manner in which Temperamental cattle respond to feed restriction (FR). Therefore, the objective of this study was to determine whether cattle temperament would influence the metabolic responses to a FR challenge in beef cattle. Angus-cross steers (16 Calm and 15 Temperamental, 216 ± 6 kg BW) were selected based on Temperament Score measured at weaning. On d 1 of the study, steers were moved indoors into individual stanchions to allow measurement of individual feed intake. Feed and water was provided ad libitum from d 1- 4 in order to determine ad libitum feed intake. On d 6, steers were fitted with indwelling rectal temperature probes and jugular catheters, and were returned to individual stalls. Beginning at 0800 h on d 8, feed was removed for a 72-h period (d 8 - 10). Feed was then provided at 25%, 50%, 75%, and 100% of ad libitum on d 11, 12, 13, and 14, respectively. Blood samples were collected every 6 h from 0 to 156 h during the FR challenge. Serum was isolated and analyzed for cortisol, glucose, insulin, NEFA, and BUN concentrations. All variables changed over time (P < 0.01). For the duration of the study, Temperamental steers maintained greater (P < 0.01) serum NEFA and less (P < 0.01) serum BUN and insulin sensitivity (calculated using RQUICKI) compared to Calm steers. Additionally, Temperamental steers maintained greater (P = 0.001) serum glucose and less serum (P = 0.001) insulin than Calm steers. These data suggest that Temperamental and Calm cattle have metabolically different responses to FR, and further implicate metabolic differences as the primary factor associated with differences observed in immune function and performance traits between temperamental and calm cattle. These differences accentuate the need for different management strategies for feeding temperamental versus calm cattle.