The relationship between herd level disease incidence and a return over feed index in Ontario dairy herds.

The objective of the current research was to examine the association of herd level disease incidence with the return over feed (ROF) (milk income minus feed cost) herd profit index offered through Canwest Dairy Herd Improvement. The lactational incidence risks (LIR) for displaced abomasum, retained placenta, clinical mastitis, milk fever, clinical ketosis, and lameness submitted by producers (n = 48) were similar to previous reports. However, there was no negative association of clinical disease LIR's with ROE Subclinical ketosis and subclinical mastitis cumulative incidence were determined during the early postpartum period by using a cow-side test for betahydroxybutyrate in milk and the California Mastitis Test, respectively. Subclinical mastitis was not associated with ROE However, a unit increase in the cumulative incidence of subclinical ketosis was associated with a decrease of dollars 0.015/cow/day in the ROE The results highlight the economic significance that subclinical ketosis may have in Ontario dairy herds.