Relationships of body condition score to production variables in high producing Holstein dairy cattle.

Practical relationships were determined between milk production, health, and reproduction with the amount and use of body fat in high producing lactating Holstein dairy cattle. Approximately 350 cows and heifers > 15 mo of age in a high producing herd were assigned body condition scores at monthly intervals for 24 mo. Production of 305-d FCM averaged 9541 kg (range 8826 to 10,818 kg). Body condition score at each of four calvings at 30, 60, 90, 120, and 305 DIM in each parity and loss in score in each lactation were summarized. Multiple regression related scores to milk and milk fat production, reproduction, and disease variables within and among lactations. No difference in score occurred at calving or at dry-off among parities. The range of body condition scores was less than is commonly reported; however, loss of condition increased with increasing parity from .3 in first lactation to .9 body condition score units in lactations > or = 4. The body condition score varied quadratically with DIM but, at a given DIM, was not related to the daily milk production on that DIM. Parity had a stronger relationship with milk and milk fat production than did body condition score. However, within lactation, body condition score at calving and the loss of score were related quadratically to milk production. No significant relationships of body condition score to the incidences of pyometra, metritis, retained placenta, cystic ovarian disease, AI per conception, days to first AI, or dystocia existed in this herd.