Evaluation of Sources of Variance in Dairy Herd Fertility

Abstract

Fertility data were obtained for the first ten cows bred in 23 herds in each of 22 artificial breeding locals for a period of four consecutive years. Analysis of variance and separation of the components indicated that 1.4(~ of the variance was due to differences between years, 4.6% to differences between locals, 7.5% was between herds within locals, 2.1% was due to the interaction between years and locals, and 4.9~/( was due to the interaction between years and herds within locals. The remaining 79.6% of the variance was estimated to be due to sampling error.