FOODS ANIMAL PRODUCTION. 459 



Siimmnry of rations fed and yields of butler fat obtained from 16 herds examined. 



' As here tabulated the weights of protein are given to the nearest 0.05 of a pound; thus, 2.51 lbs. 

 is called 2.50, etc. 



2 As here tabulated the nutritive ratios are taken to the nearest 0.5 ; thus, 6.2 is called 6 ; 6.4 is called 

 6.5, etc. 



2 Cows nearly all new milch. Nutritive ratio, 1 : 6.4. 



"The animals having the narrower ration produced on the average 0.6 lb. more of 

 butter fat in 5 days than did those having the wider. . . . 



"The animals having the larger amounts of jirotein gave on the average 0.9 lb. 

 more of butter fat in o days than did those having the smaller quantities of protein. 



"With the exception of the animals of herd 10 those which are classified as 

 receiving more than 2.3 lbs. of digestible protein were all actually receiving about 

 2.5 or more pounds of digestible protein per day. The animals of herd 10 were all 

 practically new milch . . . [which] would seem to account, in part, at least, for 

 the high yield of butter fat. 



"The largest butter-fat yields, with the exception of that from herd 10, were 

 from herds 12, 3, 14, and 1. The rations fed these herds contained, respectively, 2.99, 

 3.01, 2.66, and 2.51 lbs. of digestible jjrotein. Their nutritive ratios were as follows : 

 1:4.5, 1:5.7, 1:5.8, 1:6.2. Their fuel values were 30,750, 37,950, .33,7.50, and 33,450 

 calories. Too much imporlance should not be attached to these results, as they may 

 have been partly accidental and due to causes other than feed. It is, nevertheless, 

 a noteworthy fact that in the cases in which the cows were in about the same period 

 of lactation the yields of butter fat decreased as the protein decreased and as the 

 nutritive ratio increased. The largest yield was from a herd receiving a very nar- 

 row ration (1:4.5) and one which contained a large amount (about 3 lbs.) of digesti- 

 ble protein. . . . 



"The rations which seem to have given the best returns contained more protein 

 than Wolff's standard calls for. From the fact that the best butter-fat yields were 

 obtained .from a ration containing less than 31,000 calories of potential energy, it 

 seems fair to assume that those which contained upward of 40,000 were quite 

 excessive. 



"The evidence at jiresent at our command would seem to indicate that the quan- 

 tity of digestible protein called for by the German (Wolff's) standard is none too 

 large, and that it would be safe in the general run of cases to feed as much or even 

 more protein if we would obtain the largest yields of butter fat from our milch 



