ON INBREEDING IN JERSEY CATTLE. 



655 



Summary. 



1. In English Jersey rattle cowa giving over 1,000 gallons in one lactation are 

 found to be less inbred than the average of the breed. 



2. A possible reason for this is that yield is not inherited in an entirely autosomal 

 manner, but that one or more factors governing its production as regards both quantity 

 and quality may be sex linked. 



3. Examination of the pedigrees of the high-yielders supported this view as well 

 as the experiences of certain practical breeders. 



4. If this were the case, then the paternal grandsire would have little effect on 

 the yield of his granddaughters. 



5. Figures are quoted from the work of Gowen which show that the contribution 

 of the paternal grandsire is significantly less than that of the other three parents. 



Gowen, J. W., and 

 Mildred R. Covell 



Gowen, John W. 

 Gowen, John W. 



McPhee, Hugh C, and 

 Sewall Wright 



Pearl, R., 

 Gowen, J. W., and 

 Miner, J. R. 



Robertson, E. 



Wright, Sewall 



Wright, Sewall, and 

 Hugh C. McPhee 



References. 



(1921-1) Studies in Milk Secretion IX. Maine Agr. 



Ezpt. Stat. Bull. 300. 

 (1921-2) Studies in Milk Secretion XII. Maine Agr. 



Expt. Stat. Bull. 301. 



(1924) Milk Secretion, Baltimore. Williams & 



Wilkins Company. Price 20s. 



(1925) Studies in Milk Secretion. XVI. Progeny Per- 



formance of Guernsey Sires' Sons. 

 Maine Agr. Ezpt. Stat. Bull. 327. 



(1925) Mendelian Analysis of the Pure Breeds of 



Livestock. III. The Shorthorn. Jour. 

 Hered. v. 16, pp. 205-215. 



(1926) Mendelian Analysis of the Pure Breeds of 



Livestock. IV. The British Dairy Short- 

 horn. Jo2ir. Hered. v. 17, pp. 396-401. 

 (1919) Studies in Milk Secretion. VII. Transmitting 

 Qualities of Jersey Sires for Milk Yield, 

 Butter Fat Percentage and Butter Fat. 

 Maine Agr. Ezpt. Stat. Bull. 281. 



(1921) Notes on Breeding for Increase of Milk in 



Cattle. Jour. Genet, v. xi., pp. 79-90. 



(1922) CoeflBcients of Inbreeding and Relationship. 



Amer. Nat. v. 56, pp. 330-339. 



(1923) Mendelian Analysis of the Pure Breeds of 



Livestock. I. The Measurement of In- 

 breeding Relationship. Joiir. Hered. v. 14, 

 pp. 339-348. 

 (1925) An Approximate Method of Calculating Co- 

 efficients of Inbreeding and Relationship 

 from Livestock Pedigrees. Jour. Agr. 

 Res. v. 31, pp. 377-383. 



