Previous research on the interaction between productivity and environmental impact has focused on the
effect of changing milk production per cow, with DOM
having an effect at both the individual animal and the
supporting herd or population level. However, the roles
of other animal performance characteristics that affect
population maintenance overhead warrant further investigation. As maintenance nutrient requirements are
directly affected by BW and activity level, an opportunity to reduce total maintenance overhead through changes in BW while maintaining dairy production
would be predicted to reduce the environmental impact
of milk production. Similarly, the potential environmental effect of changes in performance characteristics such
as age at first calving (AFC), herd life, and calving
interval (CI) that affect the dynamics and size of the
supporting population have not yet been quantified.