PSVIII-5 Circulating serotonin (5-HT) concentrations are associated with failure of passive transfer in 3–5 day old dairy calves

Abstract

Abstract Calf morbidity and mortality continues to be a challenge for the dairy industry and failure of passive transfer (FPT) is associated with an increased risk of disease. Serotonin (5-HT) has recently been implicated in the dairy calf immune system, but further work is needed to investigate the precise role of 5-HT in calf health. The objective of this study was to determine if 5-HT serum concentration at 3–5 days of age was associated with FPT. Blood samples were collected from 3–5 d old dairy calves (n = 418). Blood serum was assessed for FPT (serum protein < 5.5 g/dL) and analyzed using a commercial ELISA kit to determine circulating 5-HT concentrations. The mean (± SD) 5-HT concentration was 2574 (±1007) ng/mL. A logistic regression was used to determine if FPT (outcome; n = 124/418) was associated with 5-HT concentration (predictor; low < 2502 ng/mL, high= ≥ 2502 ng/mL). The model controlled for sex, breed (Holstein or Jersey), colostrum type (replacer or pasteurized), and dystocia (hard pull/surgical delivery). Sex, colostrum type, breed, and dystocia were not associated with FPT (P > 0.05). Calves with low serum 5-HT concentrations had a 2.7 (95% CI: 1.2–7.1) greater odds of having FPT compared to calves with high serum 5-HT concentrations (P = 0.04). Higher serum 5-HT concentrations were associated with successful passive transfer, but the causal pathway is unknown. Therefore, further investigation regarding 5-HT at different time points during calfhood should be explored as a potential way to reduce FPT in neonatal dairy calves.