Effects of selenium and iodine supplementation on the growth rate, mohair production, and thyroid status of Angora goat kids

The aim of this study was to examine the effect of supplementation with either selenium (Se) or iodine (I), or both, on growth rate, mohair production, and plasma concentrations of thyroid hormones in Angora goat kids. Kids were treated with 0 or 1 intraruminal Se pellet, or treated intramuscularly with iodised oil at doses of 0, 200, or 400 mg I in a 2 x 3 factorial design. The concentrations of Se and I in the lucerne diet were 0.02 and 0.09 mg/kg dry matter (DM), respectively. Supplementary Se enhanced (P < 0.05) liveweight gain by 26% during the final month of the study, however mohair growth was not affected by either treatment. The plasma concentration of total thyroxine was increased (P < 0.001) by I treatment but decreased (P < 0.001) by Se treatment. The plasma concentration of total triiodothyronine was reduced (P < 0.001) by I treatment but unaffected by Se treatment. Thus, Se supplementation improved the liveweight gain of Angora goats but I supplementation had no effect on growth. Both Se and I treatment altered thyroid hormone concentrations, but Se x I interactions were not significant.