230 



The Journal of Heredity 



THE LIGHT SIRE 



Figure 15. King Model 18717 is a noted producer of superior offspring. He has about 

 fifty units of black (roughly about five per cent) on each side of the body. By cows like 

 himself he produced only light calves. By dark cows he produced medium and dark off- 

 spring. This is evidently the recessive color pattern in Holstein cattle. The few light calves 

 produced in crosses with dark cows were doubtless due to the heterozygous condition of the 

 dark parent. Photograph by courtesy of the Bloomingdale Farms, Somerville, N. J. 



the Connecticut Agricultural College. 

 Several leading breeders of Holstein 

 cattle and the editor of the Holstein- 

 Friesian World have very kindly sup- 

 plied information and photographs. 

 Their courtesy is acknowledged in the 

 legends to the illustrations. 



The Problem 



The problems which we set out to 

 study were : 



(1) To define and describe the vari- 

 ations in the gross amounts of white 

 spotting in Holstein cattle. The best 

 preliminary information could be ob- 

 tained, we found, from a study merely 

 of the relative areas of black and 

 white spaces in the coat, disregarding 

 for the time, the variations in the 

 character or arrangement of the spots. 



(2) To find out whether variations 

 in the amount of spotting were in- 

 herited. 



(3) If inherited, in what manner. 



Our plans for attacking this prob- 

 lem were more or less conditioned by 

 the form in which the data were avail- 

 able. We decided that the most feas- 

 ible plan was to choose individual 

 males showing great dififerences in the 

 amount of spotting, and to obtain 

 for each male (1) his spotting descrip- 

 tion, (2) the description of a random 

 sample of cows of all degrees of spot- 

 ting with which he had been mated, 

 and (3) the description of one or more 

 offspring from each of these matings. 

 This should provide a number of sire- 

 dam-offspring trios, and should afford 

 a test of the genotypes of the males, at 



