A period of energy supplementation but not the type of supplement influences the insulin response to exogenous glucose in food-restricted post-partumsuckler beef cows

Two experiments were designed to study the influence of an increase in ener gy supply on the utilization of exogenous glucose in food-restricted post-p artum Charolais suckler beef cows. in experiment 1, 18 cows were given a ba sal diet (BD) providing 0.70 of energy requirements from calving with or wi thout an energy supplement (SD) of 2 kg of rolled triticale grain starting at day 32 post partum. On day 42 post partum an injection of glucose (1.0 m mol/kg live weight) lasting 20 min resulted in a similar plasma glucose and cortisol profile in each diet group but a smaller plasma insulin increase in SD than in ED cows (146 (s.e. 37) v. 273 (s.e. 37) pmol/l, P < 0.05). Pl asma non-esterified fatty acids concentrations were reduced by the glucose injection (P < 0.01). Experiment 2 compared the efficiency of an energy sup plement in the form of concentrate (CS, maize grain, no. = 11) or forage (F S, maize silage, no. = 10) in oestrous-synchronized beef cows previously gi ven a restricted diet. Glucose injection resulted in a small increase in in sulin concentrations during infusion with a peak at 20 min (FS : 250 (s.e. 34) v. CS : 257 (s.e. 32) pmol/l, P > 0.05). No differences were observed b etween the two groups of cows for glucose, insulin and cortisol profiles (P > 0.05). Similar pregnancy rates after oestrous synchronization treatment were observed in CS and FS cows (6/11 v. 5/10). In conclusion, a period of supplementation sufficient to re-establish energy balance, but not the type of supplement, influences the insulin response to exogenous glucose in foo d-restricted post-partum Charolais beef cows.