Factors Associated to Mastitis in Cows from the Dairy Production Basin in the Northern Highlands of Antioquia, Colombia

Abstract

A study was conducted on the prevalence of bovine mastitis in a representative sample from dairy farms in the northern highlands of Antioquia, Colombia. The results of California Mastitis Test (CMT) were evaluated, as well as the Somatic Cell Count (SCC) and the bacteriological culture of milk. The risk factors associated with bovine mastitis were also analyzed, and the statistical analysis of the information was made through descriptive statistics, prevalence ratio analysis and multilevel logistic regression. The CMT test detected that 20% of the cow were affected with mastitis, the prevalence of subclinical mastitis per cow was of 39.5%, and of clinical mastitis was 1.7%. Six hundred and forty eight (648) cultures were made of milk samples, 23.9% of which came out negative, 34% positive with Streptococcus agalactiae, and 10.2% with coagulase-negative staphylococci. The regression analysis revealed that cows that had more than six months of lactation showed an Odds Ratio (OR) of 2.65 compared to cows that had one month of lactation (p < 0.05). An OR of 1.24 was found in the association between age and mastitis (p<0.05). Finally, an OR of 0.36 was found associated to washing hands compared to not doing it (p<0.05). In conclusion, a high prevalence of mastitis per cow was found. The most frequently found micro-organism was Streptococcus agalactiae. Trauma could be a major cause of mastitis since no bacterial growth was observed in 23.9% of the milk sample cultures from cow with mastitis.