Some Factors Affecting Milk Production From Grassland at the Hannah Institute, 1951–70

A study of the relationship between some farm and grassland management factors and milk production at the Hannah Dairy Research Institute in the period 1951–70 is reported. During this period various aspects of farm management were altered, and total annual milk production was increased from 28,400 to 63,900 gal. The major factors influencing total milk production, in order of declining importance, were: the overall rate of stocking, milk yield per cow, the numher of milking cows as a percentage of all animals, and the acreage of grass as a percentage of the total farm acreage. Stocking rate and milk yield per cow together explained 85% of the total variation in annual milk production. No significant relationship was found between total milk production and weight of concentrates fed/gal, the amount of fertilizer N applied/aC, rainfall and sunshine data. It is suggested that the lack of a direct relationship between milk prodnction and the amount of fertilizer N applied resulted from the contribution of N from clover and from grazing animals.