Abstract

Glucose challenge data was used to model parametersdescribing the dynamics of the glucose-insulin system such as glucose effectiveness (SG), acute insulin response to glucose (AIRg) and insulin sensitivity (SI) in dairy cows. The relationship of these parameterswith post-partum anovulatory interval (PPAI) was also determined. Twenty-five HF cows of New Zealand (NZ; n=13) and Overseas (OS; n=12) origin, were fed either pasture (n=12) or a total mixed ration (TMR; n=13) in a 2x2 factorial design. At two weeks postpartum, they were challenged intravenously with 300 mg of glucose/kg live weight. There was no effect of diet on SG(P=0.302), SI(P=0.17) or AIRg(P=0.093) despite TMR cows of both genotypes having higher values. There was no effect of genotype on SG(P=0.234), SI(P=0.742) or AIRg(P=0.385). Correlations of these parameters with PPAI were not statistically significant: SI (r 2=0.087, P=0.310), SG(r 2 = 0.001, P=0.962) and AIRg(r 2 =0.036, P=0.320). Use of this model demonstrated that insulin response parameters were not closely associated with PPAI.

PJ, Back, RC Boston, CC Palliser, ES Kolver, and LM Chagas

Proceedings of the New Zealand Society of Animal Production, Volume 67, Wanaka, 261-265, 2007