The relationship between plasma oestrone sulphate concentrations in pregnant dairy cattle and calf birth weight, calf viability, placental weight and placental expulsion.

摘要

54 Holstein cows (13 primiparous and 41 multiparous) were used to study maternal plasma oestrone sulphate during pregnancy, its relationship to birth weight and viability of calves and the time required for placental expulsion after calving. Plasmasamples were obtained from the tail vein of cows once every month from days 90 to 180 of gestation, every 2 weeks from days 181 to 270 and every day from day 270 of gestation to parturition. The oestrone sulphate concentrations were measured by radioimmunoassay. Birth weight, placental measurements, neonatal viability and the time between calving and placental expulsion were recorded. Oestrone sulphate concentrations were correlated positively (0.71>=r>=0.32, P<0.05 or P<0.01) with calf birth weight and weights of cotyledons, intercotyledonary membranes and total placenta from days 210 of gestation to 1 day before calving. Calf birth weight was correlated positively (P<0.01) with the weight of the cotyledons (0.87), intercotyledonary membranes (0.78) andtotal placenta (0.88). Oestrone sulphate concentrations were positively correlated (0.63>=r>=0.28, P<0.05 or P or<0.01) with neonatal viability after day 195 of pregnancy and were negatively correlated (-0.29>=r>=-0.55, P<0.05 or P<0.01) with the interval from parturition to placental expulsion after 225 days of pregnancy.