DAIRY FARMING DAIRYING. 911 



have a similar feeding value as a pound of grain (-=1 "food unit"). These relative 

 figures arc recommended for use in the calculation of the feed consumption of dairy 



.•(,ws by test associations. Other comparative values used in the calculations of these 

 results are: 1 lb. small grains or maize = 1 lb. molass.-s feed = 2\ lbs. hay = 5 lbs. 

 straw.— k. w. woi.i.. 



On the relation of food to the production of milk and butter fat by dairy 

 cows, F. W. WollI Wisconsin Sta. Bui. 116, pp. 85).- This is a detailed critical review 

 of experimental work on this subject, a list of references being given in anappendix. 

 The author's summary of the discussion follows: 



"Economic production of milk and butter fat by dairy cows as regards food con- 

 sumption is dependent on a number of factors, chief among which is the capacity of 

 the cow for converting considerable amounts of food material- into milk without at 

 the same time gaining in body weight. Other factors are, the stage of the lactation 

 period, the age of the cow, the amount of feed eaten, and the character of the rations 

 fed as to succulence and nutritive ratio. 



"The amount of nutrients consumed over and above maintenance requirements 

 per 100 lbs. of milk ranges in the case of different cows, at least between 26.8 and 

 80.2 lbs. of dry matter, and per 1 lb. of butter fat between 6.8 and 18.6 lbs. of dry 

 matter. The amount of net digestible protein consumed has in the same way been 

 found to range from :;.lti to 9.07 lbs. per hundred lbs of milk produced, and from 

 0.76 to 1.70 lbs per pound of butter fat. 



"Good dairy cows have the power of producing a unit of milk or butter fat from 

 a smaller amount of dry matter than cows of less pronounced dairy capacity. The 

 production of a unit of rich milk calls for a larger supply of valuable f 1 compo- 

 nents than is required in the case of poor milk. For every per cent of increase in 

 the fat content of the milk, the amount of net dry matter required for the production 

 of 100 lbs. increases about 8 lbs., and the amount of net digestible protein increases 

 about 0.S lb. The amount of nutrients consumed per unit of butter fat produced 

 decreases slightly with an increasing fat content of the milk, viz, about 0.6 lb. of net 

 dry matter and 0.08 lb. protein for each per cent of fat in milk. 



"The amount of food materials requited for the production of a unit of milk or 

 butter fat is nearly three times as large toward the close of the lactation period as at 

 its beginnings 



"Heifers requires larger proportion of nutrients for the production of a unit of 

 milk or butter fat than do older cows. Optimum results as regards the efficiency of 

 the food consumed are obtained when the cows have reached about 7 years of age; 

 the period of usefulness of cows depends on their constitutional strength and the 

 system of feeding and handling to which they have been subjected. 



"Recent evidence goes to show that the food of thedairy cow influences the quality 

 of the milk produced to this extent, that the cow will yield a maximum flow of milk 

 of the highest fat content which she is capable of producing on rations relatively 

 rich in nitrogenous substances. The productive capacity of the cow, the prices of 

 feeding stuff- and of the milk products are the main factors that will determine how 

 highly nitrogenous rations can be fed to advantage. Under ordinary conditions in 

 the north central States it will not, as a rule, be advantageous to feed rations con- 

 taining over L' lbs. of digestible protein a day, and of a nutritive ratio narrower than 

 1 :6.7, tf> cows of average dairy capacity." 



The relation of food to dairy production, F. W. Woi.l ( Wisconsin Sta. /-'<</. 

 J 17, pp. 16). — This is a popular edition of Bulletin 1 1*> of the station noted above. 



Discussion of the amount of protein required in the ration for dairy cows, 

 C. L. Beach i Connecticut Storrs Sta. Bui. S4, pp. ■'■')■ — The data upon which this dis- 

 cussion is based have been published from time to time in the annual reports of the 

 station i E. S. I;., ti, p. 458; 7, p. 603; 8, p. 430; 9, p. 786; 10, p. 681; 13, p. 983; 14, p. 

 1005). The general plan has been to ascertain the rations actually fed different dairy 



