Estrogens and piglet viability. II. Effect of estrogen on piglet viability

The effect of oestrogens on piglet viability was determined by recording the birth to suckling interval. Starting on day 109 after mating, daily blood samples were obtained from 15 Yorkshire sows. Immediately after birth, blood samples were taken from the umbilical cord and the vena cava of piglets, followed by injections of oestradiol benzoate or a saline solution via the vena cava. Body-weight gain until 96 h and the interval from birth to suckling were recorded. Total oestrone concentration in the sows' serum rose until the day before parturition, and declined sharply by day 2 post partum. Piglets given oestradiol benzoate injections had a shorter interval from birth to suckling than controls (P<0.05), and females suckled sooner than males in both the control and treated groups. No significant differences in weight gain were detected between control and treated groups at 2, 24 or 96 h. Higher (P<0.001) levels of oestrone and oestrone sulphate were found in the umbilical cord than in vena cava samples, but no correlation existed between levels of oestrogen in the 2 types of sample. It was concluded that oestrogens or other hydroxylated compounds could be acting on a control centre of the newborn piglet to cause hyperactivity, with a consequent reduction in the interval from birth to suckling..