Location: Livestock Issues ResearchTitle: Glucose, insolin, and feed restriction challenges reveal altered glucose and insulin dynamics in temperamental steers Author
|Carroll, Jeffery - Jeff Carroll|
Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/26/2014
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Temperamental cattle are behaviorally, physiologically, and immunologically different than Calm cattle. Recently the dramatic metabolic differences between Temperamental and Calm cattle have been elucidated; Temperamental cattle appear to maintain greater circulating concentrations of non-esterified fatty acids (NEFA) when compared to Calm cattle, which may influence other metabolic parameters including glucose and insulin. The objective of this study was to determine whether temperament influences cattle’s metabolic responses to a glucose tolerance test (GTT), insulin sensitivity test (IST) and feed restriction (FR). Angus-cross steers (16 Calm and 15 Temperamental; 216+/-6 kilograms body weight) were selected based on weaning Temperament Score. On day 1 steers were moved into indoor individual stanchions to allow measurement of individual feed intake. Feed and water was provided ad libitum from days 1-7. On day 6 steers were fitted with indwelling rectal temperature probes and jugular catheters, and were returned to individual stalls. At 0900 h on day 7 steers received the GTT (0.5 mililiters per kilogram body weight of a 50% dextrose solution) and at 1400 h steers received the IST (2.5 International units bovine insulin per kilogram body weight). Feed was removed for 72 hours beginning at 0800 h on day 8, and was provided at 25%, 50%, 75%, and 100% of ad libitum on days 11, 12, 13, and 14, respectively. Blood samples were collected at 15- and 30-min intervals from -60 to 150 min relative to the GTT and IST, and every 6 hours from 0 to 156 hours during the FR challenge. Serum was isolated and stored at -80C until analyzed for glucose, insulin, NEFA, and blood urea nitrogen (BUN). 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 (measured using RQUICKI) compared to Calm steers. During the GTT Temperamental steers had greater (P<0.01) glucose, decreased (P=0.03) insulin, and had greater glucose disappearance (P=0.03) yet decreased insulin:glucose (P<0.01). During the IST, Temperamental steers had decreased (P=0.04) glucose and greater (P<0.01) insulin and a greater insulin:glucose (P<0.01). For the duration of the FR challenge, Temperamental steers maintained greater (P=0.001) glucose and decreased (P=0.001) insulin than Calm steers. These data demonstrate that differences exist in the manner that Temperamental steers respond to glucose, insulin, and FR. These differences exist due to a complex, yet undefined paradigm involving stress, immune, and metabolic parameters, ultimately resulting in greater NEFA, insulin insensitivity, and reduced glucose disappearance. These differences accentuate the need for different management strategies for feeding Temperamental versus Calm cattle.