Mastitis and bovine milk production

The elite milk producing phenotype of the modern dairy cow has adversely affected its health. Diminished udder health has serious implications for milk production, leading to decreases in milk yield, milk quality and increases in somatic cell count (SCC). Increases in SCC indicate mastitis, an inflammation of the mammary gland. Mastitis is a significant production disease and a major source of economic loss on dairy farms. It is estimated that 25-40% of dairy cattle are affected at an average cost of 50-200 per animal due to therapeutic costs, reduced milk yield, milk wastage, penalties for high SCC and involuntary culling. Current mastitis control methods rely heavily on antibiotics for both therapeutic and prophylactic purposes. This is not only costly, but frequently ineffective in chronic subclinical infections. There are also increasing concerns regarding the overuse of antibiotics in veterinary medicine and the emergence of antimicrobial resistant pathogens. This has led to an increased interest in the development of novel approaches to control and treat mastitis, without negatively impacting on milk production. Alternatives currently under investigation include incorporation of mastitis resistance into modern breeding programmes, modifications to farm management practices, identification of non-antibiotic mastitis treatments and enhancement of immunity in cows. This review will discuss recent developments in the fight against mastitis.