GROWTH AND ACTH RESPONSES TO COLD STRESS OF YOUNG PIGS FED AD LIBITUM

Abstract

Twenty-four 6-wk-old pigs were housed in individual metabolism cages and exposed for 6 wk to either 2 C or 20 C with ad libitum feed and water. The pigs at 20 C and 2 C had an average daily gain (ADG) of 544 g and 343 g (P < 0.01), respectively. Feed consumption was similar for both treatments, with feed:gain ratios being significantly lower in the 20 C group during the 1st and 3rd 2-wk periods. Spleen and kidney weights were a larger percent of ingesta-free body weight in pigs housed at 2 C. The percent body weight of livers, thyroids, testicles, seminal vesicles and bulbo-urethral glands were not statistically different between 20 C and 2 C housed pigs. Body protein and ash were 5 and 1.3% lower in the 2 C pigs. Differences in plasma ACTH between treatments within day were significant. Consistently lower levels of plasma ACTH were obtained from pigs housed at 2 C.