Hormone Profile of Crossbred Goats during the Periparturient Period

The plasma hormone profile of progesterone, 17-oestradiol, prolactin, growth hormone (GH), cortisol, triiodothyronine (T₃), thyroxine (T₄) and insulin were estimated by radioimmunoassay in jugular blood samples from 10 Alpine×Beetal crossbred goats during the periparturient period. The plasma progesterone concentrations declined from day 20 prior to kidding to the day of kidding and then remained at a basal level. 17-Oestradiol concentrations declined from day 20 to day 4 prepartum, followed by a continuous increase to reach a peak at kidding. Plasma oestradiol declined abruptly on day 1 postpartum and remained low throughout the postpartum period. The plasma prolactin concentrations increased continuously from day 20 to day 10 prepartum but then increased to a peak on the day of kidding, followed by a transient decline by day 5 postpartum. The plasma GH concentrations varied significantly (p<0.01) on the different days of sampling but were highest on the day of kidding. The plasma cortisol concentration declined from day 20 to day 2 prepartum, after which it abruptly increased on day 1 prepartum to reach a peak on the day of kidding. The concentrations of plasma T₃ remained similar during the prepartum period but were minimal on the day of kidding and increased during postpartum period. The concentration of plasma T₄ was also lowest on the day of kidding and increased during the postpartum period. Plasma insulin concentrations were low in the day of kidding.