MILK 21 
are known where the addition of several “fresh” cows 
to a small herd at the same time has reduced the fat per 
cent. of the mixed milk below the standard formerly 
maintained. In the last month of lactation, when the 
secretion decreases rapidly, the proportion of solids 
usually increases, especially the fat. At the same time, 
the secretion reacts decidedly alkaline to litmus paper 
and usually has a salty taste; sometimes it has an animal- 
like odor and taste. Cows in this stage of lactation are 
called “strippers.” In exceptional cases the milk does 
not show any noticeable change in chemical composition 
during the entire period of lactation, while in rare cases 
the per cent. of solids may decrease at the end of lacta- 
tion. At different stages of the same milking the milk 
also shows a regular and constant variation in composi- 
tion, the first milk drawn containing a lower per cent. 
of fat than the last or “end” milk. Incomplete milking 
may lower the per cent. of fat, because the end milk is 
much richer in fat than the first milk. 
Transitory and irregular variations in composition 
may be observed in the milk of the same cow from day 
to day, or even in the milk drawn at different milkings 
on the same day. The fat content may show a difference 
of as much as one per cent. These variations are attrib- 
uted to change in the character of the feed, or in the time 
of feeding and watering, change of milkers, the weather, 
change of stable, and unusual occurrences (storms, stran- 
gers, etc.). The quantity of milk secreted is also affected 
by the same causes. While the feed has no pronounced 
permanent effect on the composition of the milk, a change 
from dry to green feed may cause a temporary increase 
in the fat of from 0.5 to 1 per cent., while distillery slops 
