Milk Yield of Cows. 



217 



to the production of abundant grass, be those conditions 

 local or seasonal, the maximum milk yield is usually 

 obtained. 



The quality of milk appears, however, to depend upon far 

 more numerous factors. The cattle themselves, and the 

 nutriment in their food, are regarded as the primary causes 

 of fluctuation; but the nutriment in the food depends not only 

 upon the character of the soil but also upon climatic condi- 

 tions. Moreover, the milk will vary in quality not only in a 

 general way, by at times containing more solid matters than 

 at other times, but there is distinct evidence that the con- 

 stituents of these solids also vary according to the food of the 

 cows. 



During the whole period covered by the investigations 

 referred to above, the volume of morning's milk was always 

 greater than that of the evening's. The maximum variation 

 being in the month of October, the smallest in the month of 

 July. The volume of the morning's milk in April was one-fifth 

 more than that of the evening's; in May it was one-sixth, in 

 June one-eighth, in July one- twentieth, in August one- 

 eighth, in September one-fifth, and in October one-fourth. 

 Hence the excess was greatest in October, and next in April 

 and September. 



In explanation of these facts it is pointed out that in July the 

 work of harvest keeps the farm hands busy until late in the 

 evening, and the evening's milk is brought into the dairy 

 later in that month than during any other part of the year. 

 Thus the time which elapses between two milkings is more 

 equal than during any other month. On the other hand, in 

 October, the dark mornings make the milking later than 

 usual, while the drawing in of the day causes the milking to be 

 done earlier in the evening, so that the time which elapses 

 between the two milkings is most uneven. It would appear, 

 therefore, that the morning's milk is more than the evening's 

 mainly owing to the longer time which has elapsed since the 

 last milking ; in other words, the animal has had longer time 

 in which to produce the milk. 



With regard to the influence of the period of calving, it 

 appears from the results of these observations that cows 



