Effect of dietary zinc levels on the growth and development of the gilt.

The effect of dietary Zn levels on the growth and development of gilts was studied. Sixty crossbred and purebred Yorkshire gilts weighing about 30 kg were allotted by sire into four treatment groups and blocked by the date they were farrowed into three blocks. The dietary treatments, which were the amounts of Zn from Zn0 added to the diet, were 0, 50, 500 and 5,000 ppm. Thus, the treatments were less than NRC nutrient requirement, equal to the NRC requirement, 10 times requirement and 100 times requirement for Zn added to a basal corn-soybean meal diet. Weight gain and feed efficiency were not affected by dietary treatment, although there was a trend for gilts receiving 5,000 ppm added Zn to weigh less after 20 wk. After 4 wk on the experimental diets, gilts receiving 5,000 ppm supplemental Zn had elevated serum alkaline phosphatase (SAP) activity and serum Zn levels. The activity of SAP tended to decline with age for animals receiving the other dietary treatments. Gilts receiving no supplementary Zn or 50 ppm additional Zn tended to have lower serum Zn concentrations at 4, 12 and 20 wk on the study than initially. Copper concentrations in the serum were reduced when gilts were fed 5,000 ppm additional Zn. These results suggest that gilts tolerate 5,000 ppm supplemental Zn from Zn0 during growth and development, but mineral profiles are altered.