Body Condition Score at Calving, Subclinical Ketosis, Postpartum Body Condition Score Losses, Diseases, and Fertility in Holstein Cows: Modelling Confounding Associations

Abstract

This study aimed to study the relationship between energy metabolism-related variables and conception rate at first service (CRFS) in Holstein cows. A data analysis from a large dairy farm in Coahuila, Mexico, was conducted. Records consisted of 1056 lactations (419 primiparous, 637 multiparous) from 2024. The inclusion criteria were only cows that completed a synchronization protocol and were TAI. A logistic regression model to predict CRFS was conducted. In the model, BCS at calving and postpartum diseases were not significant when both SCK and BCS losses remained in the model. BCS at calving and postpartum diseases were associated with SCK and BCS losses. Cows with BCS at calving ≥ 3.75 were 5.55 times more likely to experience BCS losses ≥ 0.75 units from calving to first breeding than cows with BCS ≤ 3.5. Cows with BCS at calving ≤ 3.5 were 0.45 times as likely to develop SCK as cows with BCS ≥ 3.75. Cows with postpartum diseases were 4.42 times more likely to develop SCK than healthy cows. The best fitting model for CRFS included: breeding season (Cool vs Hot; OR=1.25, 95% CI=1.09-2.24); milk yield at week 8 pp (for extra 1 kg of milk; OR=1.03, 95% CI=1.005-1.050); parity (Prim vs Mult; OR=1.60, 95% CI=1.21-2.12); SCK (No vs Yes, OR=1.66, 95% CI=1.23-3.42); BCS loss (≤ 0.5 vs ≥ 0.75, OR=1.51, 95% CI= 2.09-3.08). It is concluded that SCK and BCS losses were important variables associated with CRFS that were also confounded by BCS at calving and early postpartum diseases.

Keywords: body condition score, calving, subclinical ketosis, Holstein, diseases, losses, conception, fertility