Cattle, gestation, luteolysis, mastitis, subclinical
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. The control group (CMT 0), cows not presenting subclinical mastitis until 90 post-insemination days. The CMT T-1 group, 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 days 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 was evidenced a relationship between subclinical mastitis grade 2 and 3 with early pregnancy loss (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.