INHERITANCE IN CROSSES OF DAIRY 
AND BEEF BREEDS OF CATTLE 
II. On the Transmission of Milk Yield to the First Generation.! 
Joun W. GowEN 
Agricultural Experiment Station, Orono, Maine 
OUR main problems are of par- 
| rear interest to those students 
of genetics who are interested in 
the economic aspects of inheritance in 
cattle. These four problems may be 
stated as: (1) the inheritance of milk 
yield, (2) the inheritance of the butter- 
fat concentration in the milk, (3) the 
inheritance of the duration of time 
during which the milk flow is main- 
tained, and (4) the inheritance of the 
degree and kind of fleshing. 
Two methods of approaching these 
problems are possible. The first con- 
sists in analyzing the more or less com- 
plete records which are in existence. 
The second consists of making definite 
controlled matings to determine the 
inheritance of the desired characters. 
The Biological Laboratory of the 
Maine Agricultural Experiment Sta- 
tion is approaching these problems 
along both of these lines. The results 
herein described deal chiefly with the 
second mode of approach. 
The definite, controlled matings to 
produce the animals necessary for the 
analysis of these problems were begun 
in 1913 under the direction of Dr. Ray- 
mond Pearl. At the beginning of the 
war in 1917 the author took over the 
direction of the work and the analysis 
of the accumulating data. All the 
credit for the inception and organiza- 
tion of the breeding experiments con- 
sequently belongs to Dr. Pearl. The 
manner of approaching the solution of 
the data are the author’s own and he 
alone is responsible for the conclusions 
drawn. : 
In 1917 certain of the results of these 
matings on inheritance in milk produc- 
tion were presented in the Journal of 
Agricultural Research?. The material 
given herein represents the accumu- 
lations of data since that date. 
MILK PRODUCTION AS MEASURED BY 
AGE 
It has been shown by the work of 
this laboratory that milk production 
for the four main dairy breeds changes 
in a definite manner with age. This 
change is described by logarithmic 
functions whose equation may be de- 
termined. When these logar thmic 
curves are compared it is found that 
the relative increase and decrease of the 
milk yield of the different ages is nearly 
the same for each of the three dairy 
breeds—Jersey, Guernsey and _ Hol- 
stein-Friesian. This consistency of the 
effect of age changes on the milk yields 
of the different breeds allows the cor- 
rection of their milk yields and those 
of their crossbred offspring by the same 
set of correction factors determined 
as the mean for the three breeds 
Jersey, Guernsey and Holstein-Friesian. 
Whether or not the milk production of 
the Aberdeen Angus follows the same 
law as the dairy breeds is not known al- 
though there is a large amount of pre- 
sumptive evidence that it does. In 
lack of final evidence all records for the 
milk yield of the Aberdeen Angus cows 
were corrected by the same set of cor- 
rections as those for the dairy breeds. 
The age of two years has been chosen 
as the basis on which the records have 
been corrected. Thus if the crossbred 
daughter has lactation records at say 
two years, three years four months; 
and four years six months; the record 
' Papers from the Biological Laboratory of the Maine Agricultural Experiment Station, No. 
135 
Dairy and Beef Breeds of Cattle. 
2 Gowen, John W. 1918. Studies in Inheritance of certain characters of crosses between 
In Journal Agr. Research, vol. XV, No. 1, p. 1-57. 
300 
