Effects of prenatal maternal TRH stimulation on the postnatal ability of neonatal piglets to cope with a cold challenge

Eight, pregnant, primiparous sows received i.v. infusions of TRH (5 micro g/kg; TRH group) or physiological saline (0.9% NaCl; control group) from day 105 of gestation until farrowing. The plasma concentrations of thyroxine and triiodothyronine increased in sows treated with TRH. There were no differences in thyroxine and triiodothyronine between piglets born to sows in the TRH group and those of the control group. The rectal temperature of piglets born to TRH-treated sows decreased less than that of piglets born to controls after a 1-hour cold challenge. Piglets born to sows in the TRH group had higher body weights at birth, and by day 28 they were an average 600 g heavier than those born to control sows. It is concluded that prenatal maternal treatment with TRH appears to increase piglets' resistance to cold and has beneficial effects on birth and weaning weights..