Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/1997
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: There is no information whether exposure to different ambient temperatures during the neonatal period results in long-term alterations of endocrine and thermoregulatory responses to acute thermal exposures. Pigs were reared in either a cycling upper (27-32 deg C; n=4) or lower (21 deg C; n=4) thermal environment for the first 28 d of life. At 6 mo of age, endocrine and thermoregulatory responses to acute heat (34 deg C) and cold (10 deg C) exposures were determined. Neonatal environment did not influence any acute endocrine responses. Cortisol increased during both acute heat and cold exposures (P = 0.0001) although the response was greater in the heat (P = 0.003). A prolactin response occurred during acute heat exposure (P = 0.004). Growth hormone increased during acute cold (P = 0.001). There was a strong tendency for increased epinephrine secretion during both acute heat and cold exposures (P = 0.06). No significant effects of either exposure were found on norepinephrine (P = 0.9) or triiodothyronine (P = 0.11). Neonatal environment did not affect daily core body temperature (Tc) before acute heat or cold exposures, but did alter the amplitude of the 24-h Tc cycle. The amplitude was greater in animals reared in the lower thermal environment (P < 0.001). Acute heat exposure resulted in significant increases in Tc (P < 0.001) and heat production (P < 0.01). Neonatal thermal environment had no effect on Tc and heat production responses to acute heat and cold exposures. These results indicate that although early neonatal thermal environment does not have long-lasting effects on endocrine and thermoregulatory responses to acute thermal exposure, it has prolonged effects on the amplitude of the 24-h Tc cycle.