Failure of mild goitre to influence growth rates in kale-fed weaned lambs

Abstract

Extract

In previous publications (Sinclair and Andrews, 1954 and 1958), we discussed the problem of goitre in new-born lambs from ewes fed thousand-headed kale (Brnssica oleracca var. accplzalu). It was found that, under the experimental conditions at Manutuke, there was invariably, to a greater or lesser degree, an incidence of goitre in new-born lambs. In particular, when ewes were fed on kale for as long as 8 weeks before lambing commenced, the disease was severe and neo-natal mortality rates were extremely high. The incidence of goitre was greatly reduced and high death rates were prevented by closing the pregnant ewes with iodine compounds. Although there was no obvious evidence of goitre in the ewes, radio-iodine studies showed that this feed exerted an antithyroid effect in these animals (Wright and Sinclair, 1958).