A Prospective Study of the Prevalence and Predictive Risk Factors of Repeat Breeder Syndrome in Dairy Cattle in the North of Spain

Abstract

The study addresses repeat breeder syndrome (RB), a significant reproductive issue in dairy cattle, where cows fail to conceive after three or more inseminations despite appearing healthy. The research aimed to identify risk factors contributing to RB in primiparous (first-time calving) and multiparous (multiple calvings) cows on dairy farms in northern Spain. Analyzing 2370 cows, the study identified critical risk factors such as body condition loss, reproductive pathologies (e.g., dystocia, endometritis), metabolic disorders (e.g., ketosis), lameness, and mastitis. For multiparous cows, delaying the first insemination postpartum reduced the RB risk. Seasonal effects showed fewer cases when calving occurred in summer or autumn. The findings suggest that addressing these factors through improved management, health monitoring, and breeding practices can enhance reproductive efficiency, lower costs, and support animal welfare. Therefore, reducing RB prevalence contributes to sustainable dairy farming and supports societal concerns about food production’s economic and environmental impacts.This study examined the prevalence and risk factors of repeat breeder syndrome (RB) in 2370 dairy cows in northern Spain. Data collected included the prevalence of postpartum pathologies, metabolic markers, and productive and reproductive parameters. The overall RB prevalence was 21.1%. In primiparous cows, the postpartum body condition loss (Odds Ratio (OR): 2.9–8.1, depending on severity), ketosis (OR: 3.5), lameness (OR: 3.4), clinical mastitis (OR: 4.2), dystocia (OR: 5.2), and endometritis (OR: 12.2) significantly increased the RB risk. Summer (OR: 0.4) or autumn (OR: 0.6) calvings reduced this likelihood compared to winter or spring calvings. In multiparous cows, risk factors included body condition loss (OR: 2.0), ketosis (OR: 4.3), lameness (OR: 2.5), clinical mastitis (OR: 4.2), dystocia (OR: 1.9), endometritis (OR: 6.2), metritis (OR: 1.38), and subclinical mastitis (OR: 1.9). A longer interval between calving and first postpartum insemination reduced the RB risk (OR: 0.99). Overall, metabolic and reproductive disorders were significant risk factors for RB across both cow groups, while seasonal calving and delayed insemination mitigated risk in primiparous and multiparous cows, respectively.