Parity influences the utilization of exogenous glucose in suckler anoestrous Charolais beef cows

Abstract

AbstractThis work was designed to study the influence of parity (multiparous (MP, no. = 9) or primiparous (PP, no. = 10)) and feeding level (control diet (CD; 1·00) or restricted diet (RD; proportionately 0·70 of requirements) in a 2×2 factorial design on the utilization of exogenous glucose in the suckler anoestrous Charolais beef cow. Lack of ovarian activity was confirmed by low circulating progesterone concentrations measured in weekly blood samples taken after parturition. An injection of glucose (1·5 mmol/kg live weight) lasting 20 min was given 30 days and 50 days post partum. Blood samples were collected before and for 120 min after the start of the injection and plasma insulin, glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate and urea were measured. Although plasma glucose concentrations were not significantly different between treatment groups in the period immediately after the injection of glucose, CD PP animals had higher plasma insulin levels than CD MP animals (at 25 min: 596·4, 283·8, 435·1 and 309·6 pmol/l, P < 0·05 for groups PP CD, MP CD, PP RD and MP RD respectively). Plasma NEFA concentrations were initially higher in the RD groups compared with the CD groups but were reduced by the glucose injection (P < 0·001). However, the PP RD cows took longer to respond to the exogenous glucose compared with the MP RD cows (at 25 min: PP RD: 133·2 and MP RD: 57·5 eq/l, P < 0·05). In conclusion, suckler anoestrous PP cows appear to require higher plasma insulin levels than MP cows to metabolize exogenous glucose and underfed PP cows were slower to reduce plasma NEFA after glucose injection than underfed MP cows.