Insulin responses to acute glucose infusions in Buša and Holstein-Friesian cattle breed during the peripartum period: Comparative study

The aim of this study was to compare insulin responsevness to acute glucose infusion in cows of Holstein Friesian (HF) and Buša breeds during the peripartal period. Eight cows per each group (HF and Buša), were chosen. At day 7 prior to calving (ante partum) and day 14 after calving (post partum) animals were subjected to a glucose tolerance test (GTT). Blood samples were taken immediately before infusion and 15, 30, 60, 120 and 180 min thereafter. Glucose and insulin concentrations were measured in each blood sample, while BHBA and NEFA were measured only in samples taken before the infusion. QUICKY an indicator of insulin resistance in cows was calculated. Basal glycemia did not significantly differ between the breeds. Basal insulinemia was significantly higher in Buša than in HF cows in both examined periods (p<0.001, respectively). Basal NEFA levels tended (p=0.06) to be higher in Buša cows compared with those of HF ante partum, and was significantly higher (p<0.001) post partum. Basal BHBA was significantly lower in Buša than HF cows in both examined periods (p<0.01; p<0.001). QUICKI was significantly lower in Buša compared to HF cows both ante partum and post partum periods (p<0.001, respectively). Glycemia determined during GTT were higher in Buša than HF cows, both ante partum and post partum, but significantly starting from minute 15 ante partum i.e. minute 30 post partum. Insulinemia determined during GTT was significantly lower at min 15, and significantly higher starting from min 90 in Buša than HF cows, both ante partum and post partum. Results obtained in this study indicate on difference in insulin responsevness to acute glucose infusion between the examined breeds, which is probably a consequence of the difference in the degree of negative energy balance rather than of selection on high milk production. Namely, decreased insulin tissues sensitivity and decreased insulin responsiveness in Buša compared to HF cows is probably the consequence of inadequate energy intake from alimentary sources which leads to enhanced usage of energy from body reserves. [Projekat Ministarstva nauke Republike Srbije, br. 46002]