Effects of various factors on intake and efficiency of utilization of energy for milk production

Selection on the basis of milk production alone yields little information about the efficiency of conversion of feed nutrients into milk. Increased production could be the result of several factors other than increased efficiency. With the increased economic pressures on the dairy industry to become more efficient, it has become necessary to critically examine the efficiency of milk production. Accomplishments of the swine and poultry industries in breeding and feeding for increased efficiency are well known. In the dairy field the contribution of the Danish sire testing stations toward increased efficiency have been of value and should be expanded. Since efficiency of production is a cumulative expression of several processes of basically additive inheritance and varying heritability, it should be a genetically important trait of additive type inheritance. The objectives of the present analysis were to determine the effects of sire, ration, and various other factors on feed intake and efficiency of utilization of energy for milk production; and to derive an estimate of the heritability of efficiency.