Milk Production Functions Incorporating Variables for Cow Characteristics and Environment

This study provides estimates of the milk production function as it relates to feed inputs, cow characteristics and environmental variables. It is based on two physical experiments with 72 Holstein cows. The regression equation used included estimation of 27 coefficients for the variables: weekly hay consumption, weekly grain consumption, stage of lactation, cow ability, index of inbreeding, body weight, age of cow, index of cow maturity and environmental temperature. Various physical and economic relationships estimated for the function include isoquants, isoclines, marginal quantities and profit maximizing levels of various variables. Confidence limits estimated for isoquants, isoclines and optimizing feed inputs suggest greater certainty in grain recommendations than for hay recommendations. The study, while not considered final in respect to coefficients for numerous variables, suggests that with further research, many aspects of dairy cattle breeding, nutrition and management can be incorporated into a single estimated production function.