206 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



ANIMAL BREEDING INVESTIGATIONS. 



The research work in animal breeding at the experiment station of 

 the bureau near Bethesda, Md.. has continued during the year, the 

 most extensive and important investigation being the study of 

 inbreeding in guinea pigs. Twenty-four families are being inbred, 

 matings being made between litter brother and sister in each genera- 

 tion. iVll families have been thus inbred for 4 generations and 

 some for 10 generations. The data accumulated for the 4 genera- 

 tions are being compiled for a preliminary report. 



The vitality of gumea nigs that have been inbred for seven genera- 

 tions is being determined by inoculating them with tubercle baciUi. 

 Guinea pigs of equal weight and age, but not inbred, are used as 

 checks. The principals and checks are born and reared in the same 

 building and cared for and treated in exactly the same manner. 

 From results so far obtained it appears that there is no difference in 

 the vitahty of the inbred and the normal animals. Before definite 

 conclusions are reached in this matter, however, the experiments 

 must be repeated and large numbers of animals used. 



This intense inbreeding is developing in a number of families cer- 

 tain family characteristics which are shown in the color markings, in 

 size of individuals, and in length and texture of the hair. Breeding 

 for the establishing of certain coat-color patterns in guinea pigs has 

 been continued with negative results, as has also an experiment started 

 with the idea of increasing the length of ear in guinea pigs by selection. 



0\ving to an outbreak of rabies among the white bull terrier dogs 

 they were all destroyed and the work on telegony in which they were 

 used has been discontinued. 



POULTRY INVESTIGATIONS. 



MAINE WORK. 



By the plan of selection now being practiced it has been possible 

 to isolate from the flock strains or "blood lines" which are breeding 

 true to definite standards of egg production. There are now being 

 propagated (1) lines having a high winter egg production, (2) lines 

 having a medium degree of winter productiveness, and (3) lines of 

 low winter production. The results of this work are of a definite and 

 clear-cut character. 



By the application of Mendelian principles in the work with hybrid 

 poultry it has been possible to combine in one strain the ^ood meat 

 qualities of the Cornish Indian game with the good egg qualities of the 

 Barred Plymouth Rocks, thereby creating a new type regarded as 

 very desirable from the utility standpoint. 



INDEPENDENT INVESTIGATIONS. 



During the year the poultry work has been removed from Bethesda, 

 Md., where it was formerly carried on, to the bureau farm at Beltsville, 

 Md. It was deemed inadvisable to move any of the old stock, and 

 this was in consequence marketed. To replace this stock, eggs were 

 purchased from representative flocks of the following breeds: Barred 

 Plymouth Rock, White Wyandotte, Single-combed Rhode Island 



