578 EXPERIMENT STATION EECORD. [Vol.38 



DAIRY FARMING— DAIRYING. 



Influence of the age of the cow on the composition and properties of milk 

 and milk fat, C. H. Eckles and L. S. Paxmer {U. S. Dept. Agr., Jour. Agr. Re- 

 search, 11 {1911), No. 12, pp. 645-658, figs. 3). — This paper gives data on this 

 question taken from records of pure-bred Jersey, Holstein, and Ayrshire cows 

 of the dairy herd of the University of Missouri. A study is also reported of the 

 effect of old age on the composition of milk as indicated by data secured from 

 the records of two Jersey cows and one dairj- Shorthorn cow in the university 

 herd. The records used in the study consisted of what is termed the " true 

 average percentage " of fat for tlie entire lactation period of each cow. This 

 percentage was calculated from the total milk and fat production for the period, 

 the milk production being based on the actual amount of milk produced at each 

 milking for the entire period, and the fat production being based on the per- 

 centage of fat in a composite sample of five days' duration taken at the middle 

 of each month. 



It is concluded that " the percentage of fat in the milk of Jersey cows attains 

 its raaxinmm with respect to the average for the entire lactation period during 

 any one of the first three periods, but the chances appear to be greater that 

 this will be attained in the second or tliird period rather than the first. Ilolstein 

 cows almost invariably show the highest average percentage of fat for the 

 lactation period during the first period. Ayrshire cows more frequently show 

 a higher average lactation test during the first than during subsequent periods, 

 but less frequently than in the case of Holstein cows. 



" The variations in the average percentage of fat among the first few lacta- 

 tion periods are not sufficiently great to be of much practical importance, but 

 the gradual decline in average test accumulates to a figure of considerable 

 importance as the number of periods of lactation becomes greater. A low 

 plane of nutrition during growth and prior to the first lactation period probably 

 contributes materially to a decrease in the average percentage of fat for the 

 first lactation period from that which it would be if the period of growth is 

 supported by a more liberal plane of nutrition. 



" Neither the percentage composition of the milk nor the physical and 

 chemical constants of the milk fat of aged cows show any abnormalities attribu- 

 table to old age. Butter made from the milk of a cow 19 years old and in 

 her thirteenth lactation period was pronounced to be of excellent quality, and 

 kept for a period of three months at a temperature of 8 to 10° C. without 

 showing any marked deterioration." 



Management of the dairy herd, R. W. Clark {Colo. Agr. Col. Ext. Serv. Bui., 

 1. ser., No. 127 {1917), pp. 13, figs. 7). — Notes are given on dairy barns, pas- 

 tures, soiling crops, selection and feeding of dairy cows, raising dairy calves, 

 and the age at which heifers should be bred, and rations are suggested for 

 milch cows under Colorado conditions. 



Factors and methods in the profitable production of sanitary milk, W. D. 

 NiCHOLLS {Kentucky Sta. Bui. 206 {1917), pp. S-U, figs. 28).— The following 

 articles are presented : 



I. Practical means of controlling bacterial infection of milk (pp. 3-33). — 

 The author discusses the bacterial and other factors in the production of sani- 

 tary milk. 



II. Experimental study of the conditions affecting the contamination of milk 

 (pp. 34-43). — This part of the bulletin describes experiments carried on with 

 a view to determining the number of bacteria to which milk is subjected during 

 the various daily operations in the dairy barn and milk room and to determine 

 the best means of preventing bacterial contamination. The results were ob- 



