Arizona Agricultural Experiment Station. 329 



running on pasture, the cows were kept in corrals and alfalfa was 

 cut and fed to them. They have had no shelter. So it may be 

 said that our cows during this year have received about the same 

 treatment given his cows by the average ranchman. The record, 

 as showing the difference in value of the different cows, is espec- 

 ially interesting when it is known that cow No. 1 is most often 

 selected by dairymen as the best cow in the herd. 



RECORD. 



In addition to the tabulated record the following chart will 

 be of interest. Two cows of the herd calved before the end of 

 the year and four proved not to be in calf. In the case of these 

 four cows, therefore, the conditions affecting the production of 

 butter fat and milk were the same for each throughout the year, 

 and Fig. 1 is intended to show graphically their monthly va- 

 riations in pounds of milk given, per cent of fat, pounds of fat and 

 cash return during the year. 



It will be observed that the first line, showing the variations 

 in pounds of milk given, is the most irregular. This line shows 

 the average daily milk yield of the four cows for each month of 

 the year. 



The second line, showing the variation in per cent of fat in 

 the milk, indicated that as a rule an increase or decrease in milk 

 flow was accompanied by an opposite change in the per cent of 

 fat. In November, however, a decrease in milk flow was accom- 

 panied by no change in per cent of fat. In December there was 

 an increase both in the flow and in the richness of the milk, 

 while in June there was a decrease in both. Speaking generally, 

 there was a gradual increase in the per cent of fat from August to 

 May, after which there was a decrease. 



This may be taken as an indication that the highest per cents 

 of fat in milk are not maintained during the heat of summer. 



The third line, showing the production of butter fat, is nota- 

 bly the most even, the amount of butter fat given being more 

 constant than the amount of milk given or its quality. 



The figures for which the fourth line stands were obtained 

 by multiplying the pounds of fat given, and shown in the third 



