Abstract
The objective of this paper is to evaluate the microbiological state and the dynamics of the mammary infections of organic farms in North Spain to discover if the high somatic cell count (SCC) observed in these farms is associated to a high incidence of mastitis. Microbiological cultures and SCC were performed in 8,496 foremilk samples collected from 160 cows in five representative organic farms from February 2006 to January 2008. Even though 79.3% of cultures were positive, only 21.2% of the total fit our diagnosis of mastitis (clinical, subclinical and chronic). The great prevalence of Corynebacterium bovis (teat canal-region pathogen) in the positive cultures that did not fit the mastitis diagnosis criteria (nearly 70%) compared with those that did (27%) was found to be related to lack of post-milking teat disinfection. The study prevalence of mastitis was 69.2% (66.7% subclinical mastitis, 27.8% clinical mastitis); the mean monthly prevalence was 47.4%; the mean monthly incidence was 12.9% and the mean duration of infection was 3.84 ± 3.98 months The high SCC in foremilk samples from old cows (three or more lactations) not diagnosed as mastitis compared to the heifers, reflects a worsening health status of the animals over time. When compared with the conventional sector in Northern Spain, these parameters indicate a poorer udder health in the studied organic herds with a high presence of chronic subclinical processes.
Highlights
Bovine mastitis is the most frequent and costly disease for dairy producers —both in conventional and organic systems— its control being their main health challenge (Caraviello et al, 2005; Roesch et al, 2007)
The objective of this paper is to evaluate the microbiological state and the dynamics of the mammary infections of organic farms in North Spain to discover if the high somatic cell count (SCC) observed in these farms is associated to a high incidence of mastitis
Subclinical mastitis, which occurs when a pathogen infects one of more quarters but does not cause enough disruption of the secretory alveoli to result in visibly abnormal milk, are not identified but are responsible for important economic losses (Roesch et al, 2007), even with monthly control SCC being generally used as a diagnostic criterion to identify infected cows (Schepers et al, 1997)
Summary
Bovine mastitis is the most frequent and costly disease for dairy producers —both in conventional and organic systems— its control being their main health challenge (Caraviello et al, 2005; Roesch et al, 2007). Organic producers are subject to Regulation No 834/2007 (EC, 2007) on organic production This normative has a main focus on animal health and welfare —based on the prevention of disease through regular exercise, access to the open air and pastureland, Ana Villar, Gloria Gradillas, Carmen Fernández-Ruiz, Ruth Rodríguez-Bermúdez, and Marta López-Alonso the maintenance of appropriate stocking densities, and the careful control of hygiene in animal housing— the restrictions on the use of antibiotics for the treatment of clinical mastitis as well as the explicit prohibition of blanket dry-cow therapy, the mainstay of any mastitis control program (NMC, 2006) —in favor of alternative therapies such as homeopathy— can make mastitis control difficult, with special relevance to the subclinical processes that will become chronic (Doherr et al, 2007). The medical conventional mastitis control measures are more effective for contagious than for environmental pathogens (Hogan et al, 1989a); so, a higher presence of contagious pathogens would be expected in organic farms compared with conventional farming
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