Effect of Prepartum Intramammary Treatment of Heifers on Somatic Cell Count, Milk Production and Mastitis Postpartum

Abstract

Mastitis in heifers has been the topic of numerous studies in the past few decades. Many studies have concluded that a large percentage of heifers began their first lactation with intramammary infections (IMI), usually with coagulase-negative Staphylococcus (CNS) species. These bacteria are ubiquitous on skin and hair of heifers, and then colonize the teat canal and gland. Several studies have examined the outcome of prepartum intramammary antibiotic therapy in heifers and have shown antibiotics are successful at reducing infections.^1,2 However, results have varied on the benefit of reducing these infections. Oliver et al² found prepartum intramammary antibiotic therapy in heifers increased milk production ( + 1000 lb; 454.5 kg) and decreased somatic cell count (SCC) linear score (-0.6) significantly over untreated animals. Treatment was demonstrated to be profitable, as long as the increase in milk production is greater than 84 lb (38.1 kg).⁴ In the seven-state study,¹ prepartum antibiotics were effective in curing IMI in heifers, but the differences in SCC and milk production between treatment and control groups were small. The goal of this study was to treat prepartum heifers with intramammary antibiotics and monitor SCC, cultures and milk production during the first part of their lactation to determine the efficacy and value of therapy.