A period of energy supplementation but not the type of supplement influences the insulin response to exogenous glucose in food-restricted post-partum suckler beef cows
1999
Ponsart, C. | Ponter, A.A. | Khireddine, B. | Humblot, P. | Sauvant, D. | Mialot, J.P. | Grimard, B.
Two experiments were designed to study the influence of an increase in energy supply on the utilization of exogenous glucose in food-restricted post-partum Charolais suckler beef cows. In experiment 1, 18 cows were given a basal diet (BD) providing 0(.)70 of energy requirements from calving with or without 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 mmol/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 BD cows (146 (s.e. 37) v. 273 (s.e. 37) pmol/l, P < 0,05). Plasma non-esterified fatty acids concentrations were reduced by the glucose injection (P < 0.01). Experiment 2 compared the efficiency of an energy supplement in the form of concentrate (CS, maize grain, no. = 11) or forage (FS, maize silage, no. = 10) in oestrous-synchronized beef cows previously given a restricted diet. Glucose injection resulted in a small increase in insulin 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 between 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 food-restricted post-partum Charolais beef cows.
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