232 



PRODUCTIVE FEEDING OF FARM ANIMALS 



out the lactation period than cows that are thin and poor at the 

 beginning of the lactation. 



Frequency of Milking. Under otherwise similar conditions, 

 the shorter the interval between milkings, the less milk is obtained 

 and the higher are the percentages of solids and butter fat con- 

 tained therein. Where the interval between milkings is nearly 

 equal, the differences in quality will, as a rule, be small. If the 

 cows are milked three times a day, the noon milking is richest and 

 the morning milking generally lowest in butter fat, while the amount 

 of milk is least at noon and heaviest in the -morning. 



POUNDS MILK 



PERCENT FAT 



4-79% 



14.0 LBS 



FIG. 44. Normal changes in the monthly yield and the fat content of the milk from 

 dairy cows with the progress of the lactation period, based on the results obtained in the 

 Wisconsin Dairy Cow Competition, 1909-11. 



Excitement. A feverish condition is generally accompanied by 

 a decrease in milk flow and an increase in the fat content; in cases 

 of severe illness, the percentage of butter fat in the milk will, how- 

 ever, be abnormally low. Cows in heat, cows handled roughly, 

 chased by dogs, or excited through other causes, will, as a rule, give 

 a greatly diminished amount of milk, which will test very high. 



Temperature and Weather. Both excessively high tempera- 

 tures and cold, heavy rain storms are likely to cause a marked de- 

 crease in the percentage of butter fat in the milk. Periods of 

 drought, according to Van Slyke, cause a decrease in the flow of 

 milk and in the contents of casein and albumen, especially the 

 latter, while either no change or an increase in the .percentage of 

 butter fat will occur. 7 



