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Associations between Severity and Etiology of Clinical Mastitis and Pregnancy Outcomes to First-Service in Dairy Cows
The objective of this study was to describe associations between the occurrence and severity of clinical and subclinical mastitis with pregnancies per artificial insemination (P/AI) after artificial insemination (AI) at first service. A total of 3,164 cows from 4 commercial dairy farms were enrolled in a prospective cohort study between May 2011 and December 2013. Cows were submitted for first AI and pregnancy outcomes were determined by using pregnancy-specific protein B (>0.3ng/mL) and transrectal ultrasonography 32 to 39 d after AI. Clinical mastitis events were categorized as mild (abnormal milk) or moderate/severe (udder affected to animal depression or fever). Subclinical mastitis was defined when SCC exceeded 150,000 cells/mL. Udder health was categorized based on mastitis events occurring within the period from 3 d before to 32 d after first AI as: 1) subclinical mastitis only (SM); 2) clinical mastitis only (CM); 3) subclinical and clinical mastitis (SCM); or 4) no mastitis events. Chi-Square tests were used to determine associations between udder health categories and P/AI at first AI. Occurrence of mastitis was associated with reduced P/AI (P < 0.001). As compared to P/AI of healthy cows (48%), cows that experienced SM (41.8%), CM (40.7%) or SCM (30.5%) had fewer P/AI. As compared to healthy cows, the odds of P/AI were 0.8 times as likely in cows that experienced SM (P = 0.005) or CM (P = 0.04) or 0.6 times as likely in cows that experienced SCM (P < 0.001). Among cows that experienced CM, P/AI did not vary based on severity (P = 0.69) or etiology (P = 0.26). As compared to P/AI of healthy cows (48%), cows with CM caused by Gram-negative bacteria (27.8%), Gram-positive bacteria (40.5%) and cases from cows which resulted in no growth (39.8%) had fewer (P = 0.006) P/AI. We conclude that both clinical and subclinical mastitis influenced P/AI and differences in P/AI were observed among etiologies and clinical presentation. Supported by AFRI Competitive Grant no. 2010-85122-20612
Keywords:
Fertility, Severity, Pathogen