Estimating daily yields of cows from different milking schemes

A multiple regression model was used to derive equations for predicting 24 h milk, fat, and protein yields of dairy cows on either two-times or three- times-a-day milking under different testing schemes. New prediction equatio ns were developed for 72 subclasses of days in milk, parity, and season of calving for each of 18 possible three-times-a-day testing schemes and for e ach of four possible two-times-a-day testing schemes. The prediction equati ons were compared to current official factors and found to be slightly bett er than the official factors. For two-times-a-day testing schemes the accur acies of 24 h fat yield predictions from one milk weight and one fat and pr otein determination were 0.88 for an evening milking and 0.89 for a morning milking. For three-times-a-day milkings the accuracies of 24 h fat and pro tein yields from two milk weights with fat and protein contents on each wer e 0.91-0.94 depending on which two of the three milkings were observed. If only one of three milkings were recorded, then accuracies of 24 h predicted fat and protein yields dropped to 0.80-0.82. More data from herds milking three-times-a-day are needed on all breeds. (C) 2000 Elsevier Science B.V. All rights reserved.