Influence of pathogens causing clinical mastitis on local inflammatory markers and reproductive efficiency of dairy cows

Abstract

Mastitis is the clinical or sub-clinical inflammation of the mammary gland normally caused by pathogenic agents such bacteria, virus, fungi and algae. Bacteria is the main agent and can be classified as contagious or environmental. Each one presenting different characteristics and forms of control. The disease is responsible for large economic losses in dairy cattle. Public health aspects associated with milk contamination are of significant importance as well. Dairy cow reproduction is another important factor in a commercial farm, and recent studies have shown that overall health, including mastitis, have the largest impact in the sub-fertility problem normally associated with high-producing dairy cows. The interaction of reproduction and mastitis have been demonstrated in several papers and economic losses associated with antibiotics and anti-inflammatory drugs, additional timed-artificial insemination protocols and semen doses. Some experiments were carried out with the objective of demonstrating how the inflammation of udder decrease embryo survival. However, the specifics on the degree of infection and causing agents of mastitis and its effects on embryo survival is less understood. It is understood that cows affected by clinical or subclinical mastitis present lower conception rate, increase in the interval between calving and first insemination, but little have been done to specify agents, correlation with somatic cell count categories and the resulting endocrine changes associated with these different scenarios. For example, the pathogen responsible by mammary gland infection (gram-negative or positive) have different modes of action causing inflammation and should be an important factor that explains different results reproduction indices. (AU)