506. The importance of machine milking rate in dairy cow management and breeding

Abstract

An analysis has been carried out on the milk yield, milk composition and milking-rate records collected in one herd of dairy cows.It has been shown from the results of eighty-six heifers that for each pound per minute increase in inherent milking rate (i.e. peak flow) the standard lactation yield increases by 419 lb., the maximum daily yield by 0·9 lb., the lactation length by 8 days and the persistency index by 10 days, whilst the lactation solids-not-fat percentage decreases by 0·03 and the fat percentage by 0·04. All except the last coefficient were significant, although it was also shown that the relationship with solids-not-fat percentage was due to an interaction. Similarly, by the calculation of partial regression coefficients it was demonstrated that the relationship between milking rate and standard lactation yield was due to the effect of milking rate on maximum daily yield, lactation length and persistency.