Methods to Estimate Milk and Fat Yields from a.m./p.m. Plans

Under alternate a.m./p.m, component sampling, fat production on sample day must be estimated because only one of the two milkings is tested for fat. Two methods of estimating fat production on sample day were compared. In the current method, information from only the sampled milking is used to estimate fat production. In the two-weight method, the milk weight from the milking that was not sampled also is used. Error variance was less for the two-weight method than for the current method by 38% for a.m. sampling and 48% for p.m. sampling. Thus, fat production on sample day should be estimated from both milkings when they are measured.