Physiological and behavioural responses of Swedish domestic goats and their kids (Capra hircus) to 15 days of heat exposure

Abstract

Seven Swedish domestic goats (Capra hircus, 2–3 years) and their kids (37 ± 4 days) were subjected to indoor temperatures above 30°C during 15 days (periods H1–H4; periods without heat C1, C2) to study acclimation. Rectal temperature (RT) increased by 1.1°C during H1 to H3 (P < 0.001 vs. C1), but only by 0.6°C during H4 (P < 0.001 vs. C1; P < 0.024 vs. H1). Respiration rate (RR) increased less during H4 than during H1 (P < 0.001). Skin temperature increased during heat (P < 0.001), and skin evaporation (SE), which differed from C1 to H4 (P < 0.05). Goats increased water intake during heat, resulting in lowered milk osmolality while milk offtake was maintained. Kids' thermoregulatory responses resembled those of the goats. Thus, decreasing RT and RR simultaneously with increasing SE at the end of the heat indicate that goats had started to acclimate.