Factors affecting the design of milk total solids testing schemes

Abstract

SummaryAn analysis of variance was applied to the ‘within herd’ variance of milk total solids in order to find the contribution due to sampling, testing and biological variances on a balanced 8 × 8 two factor (herds and days) experiment with replicate sampling and testing. Testing samples from every consignment from 10 herds over a 12-month period showed that the mean monthy ‘within herd’ variance was 0·039 and the yearly ‘within herd’ variance was 0·085. A formula is given showing how the variance of the mean for compositional quality testing can be obtained and on which the design of testing schemes can be based.