GROWTH RATE, HORMONAL AND PHYSIOLOGICAL RESPONSES OF KIDS SUBJECTED TO THERMAL AND EXERCISE STRESS

The study was conducted to evaluate the effect of thermal stress and exercise on feed intake, body growth, hormonal and physiological changes in kids. Twelve Alpine X Beetal crossbred kids were divided into two groups so that the initial body weights of both groups were similar. The study was completed in three phases of 21 days each. In the first phase, group 1 and group 2 were kept in the shed where environmental temperature varied from 20-24 o C and RH 35-40%. In the second phase, group 1 was given 1 hour exercise on a treadmill and then exposed at temperatures 40, 42 and 44 0 C in a climatic chamber for 2 hours daily for a period of 6 days at each exposure temperature. In the third phase, group 1 was again shifted in the shed along with group 2. RR, PR and RT of group 1 and group 2 were recorded before exercise and after thermal exposure. Physiological reactions increased significantly in group 1 at temperatures 40, 42 and 44 o C. Increase in RR and PR of group 1 was significantly higher (P<0.05) and increase was in commensurate with the increase in exposure temperature but magnitude of increase in RT was not significant at 42 and 44 o C compared to 40 o C. DMI in the first and third phase was similar in both groups but it was significantly lower in group 1 during phase 2. The variation in body weight gain and feed conversion efficiency was similar in group 1 group 2 throughout the period of experiment. Serum cortisol, T3 and T4 concentration were similar in group 1 and group 2 before exercise and thermal stress; the levels of cortisol increased; whereas T3 and T4 decreased significantly in group1 due to thermal exposure. Physiological responses, feed intake and hormone concentration were impacted by thermal and exercise stress but the ADG and body weight loss were negated in group 1 due to adequate and proper nutrient supply.