EFFECT OF FEEDING LEUCAENA-LEUCOCEPHALA SUPPLEMENTED RATIONS ON THYROID-HORMONES AND FASTING HEAT-PRODUCTION IN JAMUNAPARI GOATS

Fifteen intact male Jamunapari goats, average BW 22.0 kg, were divided into three groups to investigate the effects of longterm consumption of leucaena on fasting heat production and thyroid hormones. Animals w ere offered rations containing leucaena leaves and twigs to provide ab out 0%, 40% and 50% CP in L(1) (control),L(2) and L(3) groups, respect ively, in Phase I (165 days). In the second phase (210 days) L(1) and L(3) were similar to the first phase whereas in L(2) the proportion of leucaena was reduced to provide 25% CP. Basal roughage was Zea mays ( maize), aerial part, in Phase I and Avena sativa (oat) hay in Phase II . Blood samples were collected at 100-day intervals. The mean value of triiodothyronine was 0.82 ng ml(-1), 1.00 ng ml(-1), 1.65 ng ml(-1); 0.84 ng ml(-1), 0.91 ng ml(-1), 0.96 ng ml(-1) and 0.76 ng ml(-1), 0.6 6 ng ml(-1) and 0.67 ng ml(-1) in L(1), L(2) and L(3) groups, respecti vely, on Day 135 (Stage I), Day 240 (Stage II) and Day 340 (Stage III) of feeding. Triiodothyronine was higher (P less than or equal to 0.01 ) for the L(3) group in Stage I with no differences at later samplings . Thyroxine level was not affected in this study. Fasting heat product ion (FHP) was not affected by diet (269 +/- 9 kJ per kg W-0.79 day(-1) ). It is concluded that feeding leucaena up to a level to provide 50% CP in the rations to Jamunapari goats had no effect on FHP and serum t hyroxine level.