First and Last Milk Drawn 29 
between the morning and the evening milk. In this 
instance the period from evening to morning was 
about two hours longer. The amount of variation 
that may oecur between the morning and evening milk 
is often very considerable. In the great majority 
of cases it is not more than .5 of 1 per cent, 
but variations so great as 2 or 2.5 per cent be- 
tween the milk of one morning and that of the 
preceding or following evening have frequently 
been noticed. It is probable that a part of this 
variation may be explained by the action of the 
lymphatics of the udder in reabsorbing a part of 
the fat when the milk remains for a long time 
im the vessels of the udder. 
There is also a considerable variation in the 
milk from day to day. This is usually not so 
great as between the morning and evening milking, 
but it not infrequently amounts to 1 per cent. 
Such daily variations may be ascribed to changes 
in the climate or other environment of the cows,— 
the effect of storms, the effect. of change of food, 
the effect of slight indispositions, etc.; but there 
are numerous conditions not usually or readily 
recognized by the owner that affect the composition 
of the milk. It has been noted in many instances 
that the normal effect of a slight febrile condition 
of the animal is to largely increase the percentage 
of fat and albumin. If the febrile condition con- 
tinues, and particularly if it grows more severe, 
the fat then falls as quickly as-it had risen, and 
to a correspondingly lower point. 
