Association between subclinical mastitis with early loss of gestation in a dairy cow herd

Abstract

The objective of this research was to evaluate the relationship between different levels of subclinical mastitis with the early gestation lost during the first 90 post-insemination days in Holstein dairy cattle. The research was made on a dairy farm located in Mejía, Pichincha Province, Ecuador. This research analyzed data from a sample of 619 cows during one year since October 2015 until 2016. Three experimental groups graded by the severity of subclinical mastitis and diagnosed by California Mastitis Test (CMT) were used. The control group (CMT 0), formed by cows that did not present any subclinical mastitis until 90 post-insemination days. The CMT T-1 group, formed by cows diagnosed with subclinical mastitis grade 1 up to 90 post-insemination days and the CMT 2-3 group, cows that presented subclinical mastitis grade 2 and 3 up to 90 post-insemination days. The pregnancy diagnosis was made by transrectal ultrasonography between 28 and 35 post-insemination days and a follow up ultrasound was performed at 60 and 90 days of gestation. A pregnancy loss of 12% was found between 30 to 60 and 5% between 60 to 90 days. With this result a relationship between subclinical mastitis grade 2 and 3 with early pregnancy loss was evidenced (OR 2.6, p <0.01). It is postulated that an infectious process in the udder after the insemination can induce the release of inflammatory mediators such as prostaglandin F2α that would cause lysis of the corpus luteum and loss of gestation. In conclusion, dairy cattle presenting subclinical mastitis grade 2 and 3 have a higher risk of pregnancy loss during the first 90 post-insemination days.