Abstract
Twelve adult male goats, comprising of six castrated and six intacts, (2.5-3 years; $24.4{\pm}0.62kg$) were randomly but evenly divided into two groups ($I_0$ and $I_{100}$) and fed conventional concentrate mixture along with Leucaena leucocephala leaf meal (100 g/head approx.), the latter to supply 50 per cent of the crude protein (CP) requirements. The $I_{100}$ group was provided with supplemental iodine as potassium iodide solution at 0.1 mg/day/animal. Wheat straw was provided ad libitum as sole source of roughage during the experimental period of 105 d. Blood samples were collected at the begining (0 d) and thereafter at 30, 60 and 90 d of experimental feeding. The study revealed that the serum glucose level was significantly higher (p<0.01) in $I_{100}$ group as compared to $I_0$. Haemoglobin, packed cell volume and serum concentrations of total protein, albumin, globulin, calcium, inorganic phosphorus and alkaline phosphatase did not show significant differences as a result of iodine supplementation. Though the serum levels of triiodothyronine ($T_3$) were comparable between the two groups, that of thyroxine ($T_4$) increased significantly (p<0.001) in the $I_{100}$ group. The $T_3:T_4$ ratio was also similar between both the groups. The study indicated that the adverse effect of Leucaena feeding on thyroid gland could possibly be alleviated by provision of extra iodine. However, this needs further confirmation using long duration studies.