The effect of trace element supplentation (copper and selenium) on the reproductive status of a seasonal supply dairy herd : A dissertation submitted in partial fulfilment of the requirements for the Diploma in Farm Management at Lincoln University

Abstract

Data was obtained over a period of three years and was analyzed to determine the reproductive performance of a seasonal supply dairy herd. Copper and selenium play an important role in the reproduction of dairy cattle, and the effects of supplementation of theses two trace elements was investigated. From the data, lactating cows with optimal levels of copper and selenium had increased values above non-treated animals for: the number of services per cow bred (0.22), planned start of mating to conception (4 days), calving to conception (5 days), number of empties (4), submission rate (6%), conception rate (13%), % of cows calving greater than 2 months (7.4% ). The calving pattern intervals showed a 5 day improvement to the midpoint (from 26 days to 21 days) in cows with optimal levels of copper and selenium. From the herd studied, it is evident copper and selenium deficient cows have lower fertility levels than when copper and selenium blood levels lie within the optimal range for lactating cows. Successful reproductive management requires a knowledge of the basic principles of and factors affecting reproduction, an understanding of strategies which can be employed to achieve high performance, and an awareness of existing and new technological advances which can be applied in the farm situation.