Pancreatic b-cell function differs between newborn Belgian Blue and Holstein calves

The activity of pancreatic b-cells was compared between newborn double-muscled Belgian Blue (BB, n = 42) and Holstein Friesian (HF, n = 38) calves. After an overnight fast, 3 days old calves were weighed and their withers height was measured. Blood samples were obtained before and 10 min after the infusion of a standardized glucose bolus (150 mg glucose/kg body weight). Body weights were 51.2 ± 9.03 kg for BB and 41.1 ± 5.56 kg for HF calves. A significant breed effect was found regarding the body mass index (BMI, body weight/height2) of the calves, which was 95.5 ± 11.33 for BB and 70.2 ± 7.33 for HF
(p < 0.001). BMI was significantly correlated with basal glucose (G0) and insulin (I0) levels (r = 0.45, p = 0.003 and r = 0.32, p = 0.04 respectively) in BB but not in HF calves. BB calves had significantly (p < 0.001) lower G0 and I0 levels (4.3 ± 0.67 mM and 5.10 ± 3.56 mU/l respectively), when compared to HF calves (5.9 ± 0.86 mM and 8.7 ± 5.81 mU/l). After infusion of the glucose bolus, a comparable increase in glucose was seen for BB (1.8 ± 0.63 mM) and for HF (1.6 ± 0.56 mM). On the other hand, the increase of insulin was significantly higher in HF (27.6 ± 17.43 mU/l) than in BB (18.9 ± 18.9 mU/l) calves (p = 0.04). As a result, the insulinogenic index [IGI, (I10-I0)/(G10-G0)], used as measure of early insulin secretion, was significantly higher in HF than in BB calves (p = 0.008). The higher IGI for HF calves could point to an innately lower insulin sensitivity in these calves or may be due to the higher amount of muscle fibers of the BB calves.