Live weight loss and its components in Romney ewes subjected to L-thyroxine therapy and a low plane of nutrition. Part II. Effects on some non-carcass components of live weight

Abstract

1. The effects of l-thyroxine therapy and a low plane of nutrition on some of the non-carcass components of live weight in New Zealand Romney ewes were investigated. 2. Thyroxine treatment significantly lowered the weight of the gastrointestinal tract contents. A low plane of nutrition and a longer total starvation immediately pre-slaughter had little effect in lowering the weight of the gastrointestinal contents. Alimentary tract ‘fill’ accounted for a group mean loss of live weight of up to 5 lb. 3. Thyroxine treatment lowered the weight of the empty gastric tract, while a low plane of nutrition reduced the weight of both the empty gastric and intestinal tracts. The combined treatment effects accounted for a loss of up to 3 lb. in the weight of the empty gastrointestinal tract. 4. Neither treatment significantly reduced the weight of the omental and mesenteric fat depots. 5. The weight of the thyroid gland was unaffected by either treatment. 6. A low plane of nutrition significantly reduced the weight of the liver, kidneys and the heart but had no effect on the weight of the spleen. Thyroxine therapy significantly reduced the weight of the liver and tended to increase the weight of the kidneys and the heart.