Published online by Cambridge University Press: 02 September 2010
A trial was made on a farm using seven newly calved Jersey cows to compare the actual dry-matter intake with that predicted by three commonly used multiple-regression equations. Daily average milk yields during the first 9 weeks of lactation were recorded and peaked at 27·8 kg per cow (s.e. 1·35) in week 7 of lactation. The daily dry-matter intake recorded was 19·2 kg dry matter per cow (s.e. 0·77), compared with the multiple-regression equations, which gave estimated intakes of 13·3, 16·7 and 12·5 kg/day respectively. Prediction was improved by the use of fat-corrected milk, and by taking account of source effects, such as location and the management of the herd (18·5 kg dry matter per day). A further observation trial with the same herd after 250 days from the start of their lactation indicated that the equations still underestimated the intake potential of the Jersey cow at this later stage.