Zinc Requirement of Holstein Bull Calves to Nine Months of Age

Abstract

Summary Fifteen Holstein bull calves were fed a semipractical type diet containing 8.6 ppm of zinc on an as-fed basis until 29 wk of age. Following this depletion phase, they were fed the same basal diet with the addition of various levels of zinc for 8 wk. As indicated by weight gains, feed consumption, testicle size and weight, testicle zinc content, blood zinc content, blood carbonic anhydrase activity, and clinical examination, calves fed the basal ration performed as well as those fed supplemental zinc. It was concluded that, under the conditions of this experiment, calves do not require more than 8.6 ppm of zinc in their diet for normal performance to nine months of age.