668 



EXPERIMENT STATION RECORD. 



uut, and sunflower-seed Ciike), 20 lbs. of mangel wiirzels, 6 lbs. hay, 

 and strav; ad lUntnm. Duiiug period 1 tlie grain feed was changed for 

 lot A to 6 lbs. mixed grain, and for lot C to (i lbs. of wheat bran, in 

 both cases in the place of 3 lbs. each of grain and bran. 



At souie estates there was a fonrth lot (I)) whicli received Avheat 

 shorts in the ])lace of Avheat bran, but otherwise the same as lot C. 

 Analyses of products and of fodders fed were made as in previous 

 experiments. 



Ejfcri on qnality of milk. — The average percentages of fat for all 

 cows included in the experijuents of botli years were as follows: 



Average per cent of fat in milk. 



There is no marked difference in the fat content of the milk produced 

 by the different lots during either period of the experiment. There 

 was a small decrease in the fat content of the milk produced by lot A 

 during period 1, in 11 out of 14 series, over that of lot B. From period 

 1 to i^eriod 2 there was a similar increase in the per cent of fat in the 

 milk produced by this lot. These differences are, however, in the 

 author's opinion, too small to be of any practical im|tortance. 



The complete chemical analyses of the samples of milk from the dif- 

 ferent lots also failed to disclose any decided difference in the composi- 

 tion of the milk attributable to the different concentrated foods fed, 

 and the author therefore concludes that "in the comi^arative feeding 

 trials with milch cows now continued for 7 consecutive years at this 

 station, in which 1,039 cows have been included (separated into IGl 

 lots on 10 estates in different i)arts of our country), it has been found 

 over and over again that the changes made in the food of the lots have 

 had practically no influence on the chemical composition of the milk. 

 In these experiments grain has been fed against roots, against oil 

 cake, and against wheat bran or shorts; grain sind oil cakes have been 

 fed against roots, or roots have been fed as an additional food." 



Effect on milk yield of cows. — At the beginning of the experiments 

 the cows in lots A, B, and had been in milk 93, 93, and 94 days, 

 respectively, as an average for both years. The average age of the 

 cows in lots A, B, and was 7.7, 7.6, and 7.6 years, respectively. These 

 two factors are of the greatest importnnce in determining the decrease 

 in milk yield of a number of cows during a given period. The average 



