ALBERT

Description: 1. Two trials are described in which the live weights of sheep grazing four different pastures were compared. The four pastures comprised perennial rye-grass (P), perennial rye-grass plus white clover (P + C), short-rotation rye-grass (S), short-rotation rye-grass plus white clover (S + C).2. Large and highly significant differences existed between the mean live weight of the sheep on the various pastures in each trial. Thus the P sheep had a mean live weight of 107 and 102 lb. in trials I and II, respectively, at the end of each investigation, the P + C sheep 123 and 122 lb., the S sheep 125 and 126 lb., and the S + C sheep 140 and 137 lb.3. The differences in live-weight growth on the four pastures contain two major effects; an effect due to the difference between P and S and an effect which can be attributed to the presence of white clover in the pasture treatment.

Description: This paper describes an experiment designed to test the goitrogenic effect of white clover (Trifolium repens L) in ewe lambs grown and taken through a complete reproductive cycle. The sheep were setstocked on four pastures made up of perennial ryegrass and short-rotation rye-grass, both alone and together with cyanogenetic white clover. Since these species differ in iodine content when grown on the same soil, there were probably differences in dietary iodine intake of the sheep in the four groups. Half the animals in each group were injected intramuscularly with an iodinated poppy-seed oil to serve as an iodine depot.At slaughter, 19 months from the commencement of the experiment, thyroid weights indicated a goitrogenic action in the non-injected ewes grazing short-rotation rye-grass and white clover and to a lesser extent in the non-injected ewes grazing perennial rye-grass and white clover. There was evidence of a slight goitrogenic action in noninjected ewes grazing perennial rye-grass. The thyroids of non-injected ewes had similar iodine contents, lying within the range of 0·23–0·29% of the dry weight.In injected ewes, the total iodine content of the serum was three to four times higher than with non-injected ewes and the iodine content of the thyroids was three times greater. All injected ewes had thyroids of normal weight.No effects of iodine supplementation on growth, reproduction or wool production were found.Lambs born to the ewes in the fifteenth month of the experiment were slaughtered when 3–5 months old, the age varying with pasture treatment. Thyroid weights indicated a goitrogenic effect from the clover-containing pastures.