REPORT OF THE DEPARTMENT OF 

 ANIMAL HUSBANDRY. 



THE FOOD SOURCE OF MILK FAT; WTIH 



STUDIES ON THE NUTRITION 



OF MILCH COWS.* 



W. H. JORDAN, C. G. JENTER AND F. D. FULLER. 



The tests herein reported are in continuation of one given in 

 Bulletin 132 relating- to the food source of milk fats. The 

 conclusion reached in that experiment, that part, at least, of 

 the milk fat comes from the carbohj'drates, is confirmed; and 

 other facts relating to metabolism and utilization of food by 

 milch cows are brought out. 



Three cows were used: Cow 12 fed a fat-poor ration in which 

 the protein supply was gradually decreased from 2.G lbs. daily 

 to l.G lbs. and then gradually restored to the maximum, with 

 accompanying increase and decrease in carbohydrates so that 

 the digestible dry matter of the ration was kept fairly uniform; 

 Cow 10 fed a ration with normal supply of fat at first which 

 was gradually increased to 1.4 lbs. daily, then gradually restored 

 to the normal; Cow 2 fed the herd ration having a nutritive 

 ratio about 1:5.6. These rations were quite varied in character 

 and contained some fat-extracted foods; yet showed a quite 

 uniform digestibility of about 70 per ct. of the dry matter. It 

 is believed that this figure represents fairly the digestibility of 

 rations made up in part of silage and containing a fair propor- 

 tion of high class grains. A widening of the nutritive ratios 

 appeared to render rations less digestible, especially the pro- 

 tein. The marked changes in protein content and in fat content 

 of rations did not produce noticeable changes in the character 



^\ lepriut of Bulletin No. 197. 



