GENERAL PROBLEMS IN DAIRY HUSBANDRY 345 



duced 1,259.0 Ibs. butter fat in a single year, and Segis Pietertje Pros- 

 pect, another Holstein, holds the record for milk production, with 

 37,384.1 Ibs. milk to her credit in one year when 6 years old. Other 

 records of champion cows are given in Chapter XXIV, with statements 

 concerning the rations which were fed them in making their phenomenal 

 productions. 



II. FACTORS INFLUENCING THE COMPOSITION AND YIELD OF MILK 



551. Composition of milk. The milk of different breeds of cows and 

 even of individual cows of the same breed varies quite widely in com- 

 position. While the fat content may range from less than 3 per ct. 

 to 7 per ct. or over, there is much less range in the other constituents. 

 The milk sugar commonly ranges from 4 to 5 per ct., the casein from 

 2 to 3 per ct., the albumin from 0.4 to 0.9 per ct., and the mineral 

 matter from 0.6 to 0.9 per ct. 



The average composition of milk from the different breeds is shown 

 in the following table : " 



Composition of milk of different breeds 



Breed Total solids Pats 



Per ct. Per ct. 



Jersey 14.70 5.35 



Guernsey 14.49 4.98 



Devon 14.50 4.60 



Shorthorn 13.38 4.05 



Brown Swiss 13.27 4.24 



Ayrshire 12.61 3.66 



Holstein-Friesian 12.00 3.45 



The Jerseys and Guernseys give the richest, and the Ayrshires and 

 Holstein-Friesians the poorest milk. However the breeds which give 

 the richest milk usually yield a smaller quantity, so that the amounts of 

 fat and total solids produced are nearly the same for all of the recog- 

 nized dairy breeds. 



Eckles and Shaw 12 have shown that the sugar and albumin content of 

 milk varies but little with either breed or individual, while there is a 

 greater range in the percentage of casein. Milks rich in fat are general- 

 ly high in casein, but the casein content does not increase in the same 

 ratio as the fat content. According to Hart and Tottingham 13 for each 

 100 Ibs. of fat in Jersey or Guernsey milk there are as a rule 55 to 65 

 Ibs. of casein, while in Ayrshire and Holstein milk there are 65 to 75 

 Ibs. The ratio of fat to casein shows considerable variation among cows 

 of the same breed. These facts are important in cheese making since 

 the yield of cheese depends not only upon the amount of fat in the milk 

 but also upon its casein content. A milk testing 6 per ct. of fat will not 



"Chiefly from Wing, Milk and its Products, p. 33. 

 "U. S. Dept. Agr., Bur. Anim. Indus., Bui. 156. 

 ^Agricultural Chemistry, p. 291. 



