Abstract
From a conception that the effects of estrogen treatment on lambs would be displayed more in high level of nutrition than in low level, the authors divided grazing lambs into two groups to compare the estrogen effect under different nutritional condition. One group was given concentrates (group A), but the other was not (group B).
The animals used were twelve yearling wethers. The skull and long bones of the right hind leg were measured mainly. The yields of meat and fat in the right hind leg was weighed, too.
The results are as follows:
1) Bone weight was greater in the estrogen treated animals than in the intact control in both group, especially remarkable in group A.
Bones were larger in size in the treated animals than in the control in group A, but no difference was found between these animals in group B.
2) An increase in weight of the meat and fat of the right hind leg was found in group A, but not in group B. Therefore, the weight ratio of meat and fat to bone was higher in the treated animals than in the control in group A, but little difference was recognized between these animals in group B. These facts lead to conclusions that the effect of estrogen is positive on yearling wethers at high level of nutrition, at least at their right hind leg.
3) Estrogen seemed to promote the ingrowth of new bone from the endosteum, thicken the bone wall, and, moreover, promote calcium deposit on the thickened bone wall. The increase in weight of bones by estrogen treatment seemed to be due to the reason mentioned above.
