Some Effects of Different Kinds of Hay in the Ration on the Performance of Dairy Cows

Abstract

Summary Experiments have been carried out at the Beltsville Station of the Bureau of Dairy Industry for the last 10 years in which cows have been kept continuously for long periods on rations of grain and hay without pasture. The general health, reproductive capacity, milk yield, and staying powers of the cows have been studied on rations of which the roughage consisted of various grades of alfalfa and of timothy hay. On the rations containing a liberal proportion of alfalfa hay of high quality the cows have maintained their health, milk yield, and reproductive capacity for periods ranging up to more than 7 years. When the roughage consisted of timothy hay of mediocre or low quality, the milk yield has been: somewhat reduced, the health and staying powers of the cows have been decidedly less satisfactory than on the alfalfa rations, and the reproductive capacity has been very seriously interfered with. There has been some difficulty about producing pregnancy in the cows on such rations and a very marked tendency for them to throw premature calves which either are dead or are weak and often blind. Five cows which were kept for periods o from 9 months to somewhat more than 3 years on rations of grain and U. S. No. 3 timothy hay have given birth to 10 calves, all of which were born somewhat prematurely, and none of which was normal. Six were born dead, the other 4 were weak and 3 of them were blind. These abnormal calvings took place in spite of the fact that the cows were carefully protected from infectious abortion, and were shown to be free from this disease throughout the experimental period both by the agglutination test and by bacteriological examination of the stillborn calves. Experiments have been started to learn to what extent the poor quality of the timothy hay was responsible for the abnormal calvings in these experiments. This part of the work is still very incomplete but 1 cow, which has been kept for more than 4 years on a ration of grain and U. S. No. 1 timothy hay, has given birth to 3 calves, all of which were alive and normal, and none of which was born as much as 14 days before it was due.