Iodine supplementation to a diet containing Leucaena leucocephala leaf meal: consequences on nutrient metabolism, clinical chemistry and immunity of goats

Abstract

The present study was aimed at investigating the metabolic effects of iodine supplementation in goats when fed on a diet containing Leucaena leucocephala, intended to create mild iodine deficiency. Two groups of indigenous adult goats were fed on a leucaena leaf meal-based diet without (CON) or with 0.1 mg iodine per day per animal (EXP) for a period of 180 days. Dry matter intake and dry matter digestibility were higher (P < 0.05) in the EXP group. The retention of nitrogen and phosphorus was higher (P < 0.05) in the EXP group. Retention of calcium was also higher (P = 0.082) in the EXP group. The net loss of bodyweight in the CON group (−1.21 kg) was reversed in EXP goats, which showed a net gain (+1.79 kg). The serum metabolic profile reflected a positive influence of iodine supplementation, which also induced greater (P < 0.001) circulating thyroxine concentration. The cell-mediated immune response was higher (P < 0.05) in the EXP group, whereas humoral immunity remained unaltered. The results suggested that supplementation with extra iodine could be used as an effective strategy to counteract functional disorders of the thyroid and associated adverse effects induced in goats by feeding of leucaena leaf meal.