Prevalence and risk factors related to anovular phenotypes in dairy cows

The objective of the current study was to evaluate relationship body condition score (BCS) at 35 d in milk (DIM), production, diseases, and duration dry period with prevalence anovulation 49 DIM then, specifically, each anovular phenotype. We hypothesized that follicular phenotypes, classified based on maximal size follicle, have different etiologies. A total 942 lactating Holstein cows (357 primiparous 585 multiparous) from 1 herd had ovaries evaluated by ultrasonography ± 3 detect absence a corpus luteum (CL), measure diameter largest follicle. Cows were as cyclic if CL observed least 2 examinations, or no either examination. considered divided into groups follicle follows: ranging 8 13 mm, 14 17 ?18 mm. for following diseases: retained placenta, metritis, hyperketonemia, mastitis, lameness, respiratory problem, digestive problem. At DIM, BCS determined, yield individual recorded. 28.5% (268/942) anovular. Anovular longer periods (90 vs. 71 d) smaller than (2.83 2.99). single disease multiple diseases 3-fold increase odds being anovular, respectively. follicles ranged 4 50 phenotype, among cows, mm 29.9 (79/264), 37.5 (99/264), 32.6% (86/264), those (104 74 d), whereas medium intermediate days (99 d). small greater cows. For almost all risk factors, large (?18 mm) similar (8–13 mm). Thus, periods, less factors anovulation. Moreover, distinct phenotypes differed.