Clinical mastitis: Incidence, etiology and treatment in organic and conventional dairy herds

Abstract

ABSTRACT

Organic food production is a growing sector worldwide and anticipates to the consumer growing demand for food produced on a sustainable way, without the use of antibiotics, chemicals and pesticides, and better animal health and welfare. This report compares health and welfare between organic and conventional dairy farms by a literature review and a field study done in Alberta, Canada, with emphasis on clinical mastitis incidence, etiology and antibiotic usage. Animal welfare in organic farming is on average better than in conventional dairy farming, but health is not necessarily better. Organic regulations and management standards cannot guarantee better health because they do not influence management style. In most studies on health and welfare in organic dairy farming, mastitis is used as a parameter to measure animal health. In these studies, incidence of clinical mastitis varied from a lower incidence to a same or even higher incidence rate on organic farms compared to conventional. In several studies, distribution of mastitis pathogens cultured from cases of clinical mastitis showed a slight tendency towards more contagious pathogens in organic farms compared to conventional farms. Antibiotic resistance is expected to be lower on organic farms, but no general higher susceptibility of mastitis pathogens to antimicrobial drugs was proven in any of the studies, except in the USA, where difference in antibiotic usage between organic and conventional dairy farms is very high. In the field study, which was performed within the Alberta Organic Dairy Research Project, all clinical mastitis cases in organic farms were sampled and cultured over a period of 2 months. Results were then compared with data of conventional farms obtained from a national cohort study about udder health, performed by the Canadian Bovine Mastitis Research Network (CBMRN). Unfortunately, no associations with production method (organic vs. conventional) could be made for incidence and etiology of clinical mastitis and antibiotic resistance at this time, because of the low number of samples collected so far.

Abbreviation key: CNS = coagulase-negative staphylococci, CON = conventional, IRCM = incidence rate of clinical mastitis, ORG = organic