Influence of a glucose load in fed or unfed lambs on blood metabolites and hormone patterns

Four Suffolk wether lambs were used in a crossover design to determine the effects of a 3-d feed and water deprivation period on metabolic and hormonal responses to a glucose load. During each period of the crossover design all lambs were limit-fed a 36% concentrate diet for 16 d then two lambs were deprived of feed and water for 3 d. All lambs were then limit-fed the 36% concentrate diet. Glucose loading tests were performed before feeding on d 1, 5, and 9 of the realimentation period. Ten milliliters of a 2.5 M glucose solution were infused into the right jugular vein and blood samples were obtained from the left jugular vein at intervals for 4 h after infusion. Plasma or serum samples were analyzed for insulin, growth hormone (GH), somatostatin, prolactin, glucose, free fatty acids (FFA), and urea N. At the end of the period in which feed was withheld, fed lambs had greater (P < .09) serum insulin and lower plasma FFA (P < .01) and somatostatin (P < .05). On d 1 of realimentation, previously unfed lambs had greater postinfusion GH (P < .01), FFA (P < .01), and glucose (P < .04) concentrations. Previously unfed lambs also had a slower (P < .01) glucose fractional removal rate and longer (P < .02) glucose half-life than fed lambs on d 1 of realimentation, but they had a shorter (P < .13) glucose half-life than fed lambs on d 5 of realimentation.(ABSTRACT TRUNCATED AT 250 WORDS)