The Lactation Period 37 
normal wild or semi-wild cow would be likely to pro- 
duce in a year. Numerous cows have lived that have 
produced more than ten times this amount, or 24,000 
pounds of milk in a year, the largest amount on record 
being 80,3184 pounds of milk given by the Holstein 
cow, Pietertje 2d, in 1888. 
Factors in the production of milk.—The chief fac- 
tors on which the production of milk depends are: 
’ (1) Maternity, or the period of lactation; (2) the 
inherent capacity of the cow, which in general is 
largely determined by her breed and hereditary char- 
acteristics, but always to a greater or less extent inde- 
pendent of them; (3) the amount and character of 
the food supply. 
The lactation period.—As has already been stated, 
the domesticated cow has been developed so that the 
production of milk is practically continuous. Never- 
theless, pregnancy and parturition play a very impor- 
tant part in the production of milk. While cows 
may, and often do, secrete milk continuously for two, 
three or four years without producing a calf, on the 
other hand, the birth of a calf serves to stimulate 
the secretion of milk to such an extent that prac- 
tically all dairymen are agreed that milk is produced 
under the most favorable conditions when the cow 
produces a calf at regular intervals each year, and 
this regardless of the value of the calf when born. 
It is also found that a period of rest before par- 
turition is essential to the largest production of milk 
after the calf is born; that is to say, the cow will 
secrete more milk in a year if she goes dry for two 
