Stillbirth parturition reduces milk production in Holstein cows

Stillbirth is defined as calf mortality shortly before, during, or shortly after parturition. Economic losses to the dairy industry in the U.S. just due to the loss of replacement heifers were estimated to be $125 million per year. Our objective in this study was to evaluate the effect of stillbirth on the dam's subsequent lactation. Data were collected from 20 farms in the U.S.A. (19 from NY, one from IN) from May 2005 until September 2006. Calving-ease scores (scale of 1-5; no problem and extreme difficulty, respectively) and stillbirths were recorded by farm personnel. We used 32,299 calvings for the final analysis where 6.5% of the calvings were stillbirths. The incidence of stillbirths for primiparous cows was 10.7% (of 11,891) and 4% (of 20,408) for multiparous cows. Stillbirth parturition significantly reduced milk production (-1.1 kg/day). The losses in milk production were evaluated in a generalized mixed linear model analysis. The daily milk production for cows with stillbirths was 34.2 kg, compared to 35.3 kg for the cows that had a live calf. Milk-production reduction was greatest early in lactation and declined afterwards. Economic losses from stillbirths include not just the lost calf, the reduced survival, and increased days open but also the decreased milk yield.