ENVIRONMENT AND BREEDING 
AS FACTORS INFLUENCING 
MILK PRODUCTION 
ANDREW C. MCCANDLISH 
Iowa State College of Agriculture and Mechanic Arts, Ames, Iowa 
ILK is the one indispensable 
human food and its consump- 
tion has a direct bearing on the 
welfare of the nation. The problem 
of the dairy farmer is to furnish milk 
to meet the needs of the people and at 
the same time realize a fair profit from 
it. The demand for milk and dairy 
products is increasing as the population 
of this country is increasing more 
rapidly than is the number of dairy 
cattle. More dairy cattle are needed, 
but, what is of even greater impor- 
tance, better cows are needed. Cows 
of higher producing ability will not only 
increase the available supplies of dairy 
products but they will give more 
economical production. 
EXPERIMENTS WITH SCRUB COWS 
In an effort to demonstrate the 
possibilities of improving a herd of 
poor cows, work with a scrub herd was 
undertaken at the Iowa Agricultural 
Experiment Station in 1907 and is still 
being pursued. A number of scrub 
cows were purchased in an isolated 
region of Arkansas and brought to 
Iowa. 
These animals were very inferior, 
being as far removed from the ideal 
dairy type as it is possible to get and 
were apparently of very low produc- 
ing capacity. So far as was known no 
purebred bulls had previously been 
used in the section from which the 
animals came. The experimental ani- 
mals had always been allowed to rustle 
for a living, being forced to subsist on 
the rather scant supply of grass and 
hay available. Nothing was known 
of their previous milk production as 
their sole function had been to supply 
a little milk for family use and to raise 
their calves until they were able to 
forage for themselves. 
PLAN OF INVESTIGATION 
These scrub cows and their heifer 
calves were put in the Iowa Experi- 
ment Station herd and given the same 
feed and care as the purebred dairy 
cattle maintained there. The condi- 
tions under which the animals have 
been kept have remained fairly uniform 
during the twelve years’ work. 
Accurate records of the milk and 
butterfat production of these animals 
have been kept and with their aid the 
animals have been fed according to 
their production. The keeping of these 
records throughout the lifetime of the 
original animals of the experimental 
herd gave a basis for the determination 
of the influence of environment on the 
production of milk and butterfat. 
The scrub cows were mated to pure- 
bred sires of the Holstein, Guernsey, 
and Jersey breeds and the heifer calves 
resulting from such matings were 
maintained under the same conditions 
as the other animals. The heifers by 
purebred sires were bred to other 
purebred sires of the same breed and 
the heifer calves resulting from such 
matings were also kept for dairy pur- 
poses. Records are now available on 
two generations of grades descended 
from the scrub cows and one animal 
of the next generation has just entered 
the milking herd. 
In comparing the records made by 
cows at different ages it is necessary 
that an age allowance be made as the 
maturing of a cow has a considerable 
influence on her producing ability. 
For this reason all records of the scrub 
cows and their descendants have to be 
