Abstract :
Goat keeping is feasible for smallholder farmers in many world regions especially those
best suited for extensive management. However, summertime grazing in arid zones
entails major challenges to animal thermoregulation and well-being. An experiment
was conducted to evaluate the thermoregulatory performance and selected hemogramic
parameters in intensively (INT) or extensively (EXT) managed goat kids (N = 14). We applied
a previously established technique to evaluate body thermal state of freely ranging animals,
in which contemporaneous temperatures of the core (Tc) and periphery (Tp) are chronically
recorded. Animals were initially kept for 12 days under INT management. Subsequently,
seven animals were transferred to a grazing pasture and gradually transitioned over a fourday
acclimatization period, then kept for the last 22 days under EXT conditions. Water
drinking was limited to twice daily in both groups. Excessive solar radiation-induced heat
load – with daytime black globe temperatures (Tbg) often exceeding 40 ◦C – under EXT was
primarily responsible (r2 = 0.49; P < 0.05) for 0.57 and 1.72 ◦C rises in Tc and Tp, respectively,
over INT kids. Unlike the typically biphasic pattern noticed for daily temperatures of both
body sites in INT goats, that of EXT counterparts became rather polyphasic, whereby water
drinking had drastic and prolonged thermolytic effect, inducing 0.40–0.41 and 0.79–1.45 ◦C
declines in Tc and Tp, on midday and afternoon watering bouts, respectively. Despite indication
for added daytime heat load, EXT goats displayed lower early morning Tc than INT.
All animals exhibited hypohydration, as reflected by rises in hematocrit, serum osmolality,
albumin, potassium, and sodium, being more pronounced in EXT conditions. Results
emphasize the excessive thermophysiological strain facing grazing animals in arid zones
during the summer
