Objectives of this study were to investigate the accuracy of alternate
testing plans of milk recording. From 20 herds enrolled in official m
ilk recording, data were collected monthly: yield of evening, morning
and daily milking and start of milking in the herd. Milk samples were
analysed for fat and protein content. The correlation coefficients bet
ween the a.m. or. p.m. milking and daily yields were in the range of 0
.90 to 0.98. Accuracies for estimating total daily yield from a.m. or
p.m. tests were more than 95% (fat yield more than 90%). Bias in depen
dence on cow average or herd average of milk yield for the test were f
ound. Standard error for predicting daily yield was not reduced by usi
ng multiple regression factors. Nevertheless accuracy of estimating of
lactations yield by alternate recording is high. The mean deviations
between the two recording plans were lower than 0.3%.