20 Experiment Station Bulletin 345 



The Holstcin cows were divided into two groups: six high-test cows 

 and seven low-test cows. The lower group was studied in detail. Within 

 this group one cow gave milk low in fat, total protein, and lactose, but 

 unusually high in ash; two gave milk low in total protein, but average in 

 lactose; three produced milk low in both total protein and lactose, and the 

 last member of the group was low in total protein and high in lactose. 



In general, of the solids-not-fat fraction, lactose was found to com- 

 prise over 50 per cent, total protein about 37 per cent, and ash about 8 

 per cent, jersey milk contained the greater percentage of total protein, 

 casein, albumin, calcium, and phosphorus; Holstein milk contained the 

 greater percentage of proteoses-peptones, nonprotein-nitrogen, lactose, 

 and ash. There was no direct correlation between the low-test group of 

 Holsteins and abnormally low values for the individual constituents within 

 the solids-not-fat portion. 



Of the total protein fraction about 80 per cent was casein ; albumin, 

 proteoses-peptones, and nonprotein-nitrogen each contributed 6 to 7 per 

 cent. Jersey milk was richer in casein and albumin. Holstein milk con- 

 tained the greater percentage of proteoses-peptones and nonprotein 

 nitrogen. Over one half of the low-test Holstein group remained ab- 

 normally low in casein. There was no direct correlation between the 

 low -test group and abnormally low values for the remaining minor pro- 

 tein constituents. 



Of the ash fraction about 25 per cent was calcium oxide and about 26 

 per cent was phosphorus pentoxide. Jersey milk contained considerably 

 more calcium and phosphorus than did Holstein milk. There was a 

 direct correlation between the low-test group of Holstein cows and ab- 

 normally low values for both calcium and phosphorus. Six out of seven 

 low-test Holsteins gave milk low in both calcium and phosphorous. 



In general the stage of lactation exerted an influence on the variations 

 in proteoses-peptones and nonprotein-nitrogen as well as albumin. The 

 experimental work indicates that there was such an individual variation 

 within and between the breeds that no single constituent within the solids- 

 not-fat portion consistently accounted for the milk's being low in solids- 

 not-fat. 



Of the ten sires used, one Jersey and one Guernsey increased milk 

 production. Four decreased the fat percentage and increased the solids- 

 not-fat percentage; three increased both fat and solids-not-fat percentage; 

 two decreased both, and the other sire increased the fat percentage and de- 

 creased the solids-not-fat percentage. One Jersey sire which decreased 

 milk production 881 pounds, increasing the fat percentage by 0.31 per 

 rent and the solids-not-fat percentage by 0.17 per cent, and a Guernsey 

 sire which increased milk production 1,877 pounds, while decreasing the 

 tat percentage by 0.22 per cent and solids-not-fat by 0.13 per cent, are 

 the only sires of the group that changed the fat and solids-not-fat from a 

 normal relationship of fat to solids-not-fat. 



The composition of milk from the dam and daughter comparison 

 made in this study indicated that eight of the sires did not transmit a 

 normal fat and solids-not-fat percentage relationship to their daughters 



