Date of Award

Spring 5-18-2018

Degree Type

Honors Thesis

Degree Name

Master of Science (MS)


Animal Science

First Advisor

Dr. Whit Stewart


Mastitis is one of the leading reasons for culling ewes from U.S. flocks, and subclinical mastitis indicated by high somatic cell counts (SCC) in milk has also been shown to negatively impact ewe productivity. However, means to reduce subclinical mastitis and consequential effects on lamb production are sparse. A previous study which found deprived zinc levels in ewes with high SCC suggests that ewes supplemented with zinc may exhibit lower SCC and increased lamb performance (Murphy et al, 2018). In this study, yearling ewes (n = 59) were provided zinc above dietary recommendations during gestation and the effects on lamb performance measured by visual scores at birth and by weight gain. Ewes were divided into three treatment groups in which each ewe received one pound of a zinc sulfate fortified supplement containing 40 mg/kg zinc (control), 500 mg/kg, or 1000 mg/kg from approximately day 70 of gestation until parturition. Providing dietary zinc concentration during gestation did not affect lamb vigor scores, lamb weights, nor pounds of lamb weaned per ewe, but did increase lamb survival (P < 0.05). Pending serum zinc levels and somatic cell counts, along with data from two concurrent collaborative studies will provide further insight to the significance of this project.