Maintenance energy requirements of dairy cows

Abstract

Agnew et al. (2000) and Kebreab et al (2003) report that cows in recent years yielding up to 160 MJ milk/d (51.6 kg 4% fat-corrected milk, FCM) had a mean metabolizable energy requirement for maintenance (MEm) of 0.63 MJ/kgW⁰.⁷⁵. Reasons of Agnew et al. (2000) for that being 30% greater than the AFRC (1993) value of 0.48 MJ/KGW⁵ include a high fibre diet, which was not given to the cows studied, and grazing activity, though there was little grazing it these studies. Agnew el al. (2000) and Yan et al. (2003) appear to regard improved genetic merit as the primary cause. There is some variation among 'Bos taurus' breeds in their MEm which is about 17%greater than for 'B. indicus' (SCA 1990); it is improbable that it could be a further 30% greater for cows improved genetically.