ANNUAL REPORT, 1943^4 65 



breeding has increased longevity as measured by the age at death of birds in the 

 high and low lines. 



There is some evidence to indicate that inbreeding will uncover weaknesses 

 that produce excessive mortality. 



A preliminary report on the character of the lethal mutation that appeared 

 in the high line in 1943 was published in the American Naturalist in 1944. 



Genetic Laws Governing the Inheritance of High Fecundity in Domestic 

 Fowl. (F. A. Hays and Ruby Sanborn.) Factors governing the inheritance of 

 high intensity are less well understood than are the factors concerned in the 

 inheritance of other characters affecting egg production. Recent studies have 

 shown that intensity is the most variable character in our flock and that it bears 

 an important relationship both to egg size and to number of eggs. .The data 

 indicate that intensity of laying responds to selective breeding. 



Winter pause is governed both by genetic factors and by environmental con- 

 ditions. Studies are being carried on to bring out the importance of inheritance 

 in controlling this character. 



Recent studies have been directed toward the possibility that other inherited 

 factors, aside from the five well-recognized characters, may affect egg production. 



A Study of Fertility Cycles in Males. (F. A. Hays.) The phase of this project 

 concerned with the use of sex hormones in regulating male fertility was begun 

 in the spring of 1944. Preliminary results indicate that sex hormones may be of 

 value in stimulating spermatogenesis in males that are 36 months old, but not 

 in younger males. 



Physiological Relationships Between Molting Behavior and Fecundity Charac- 

 ters. (F. A. Hays and Ruby Sanborn.) Extensive data on molting behavior 

 and results of selective breeding are available for six generations. One line was 

 selectively bred for a short period of laying after the onset of annual wing molt. 

 A second line was developed for the ability to lay for a long period after the onset 

 of annual wing molt. The second line were superior producers. 



A Genetic Analysis of Rhode Island Red Color. (F. A. Hays.) Two lines have 

 been developed: the first, genetically late in sexual maturity; and the second, 

 genetically early maturing. Differences in feather color between the two lines 

 are being studied. Colorimeter studies of feather pigments indicate a multiple 

 factor inheritance of feather color in Rhode Island Reds. 



Miscellaneous Genetic Studies. (F. A. Ifays.) The sex-linked gene E for early 

 sexual maturity has been eliminated from some crosses between Barred Plymouth 

 Rocks and Rhode Island Reds, to study the effect of autosomal gene E' alone 

 on age at sexual maturity. A line lacking both genes E and E' has been estab- 

 lished. Appropriate crosses have been made for these tests. 



Progress has been made in separating the sexes of Rhode Island Red chicks 

 on the basis of down color. A gold bar line that shows sex-dimorphism at hatch- 

 ing has been developed. 



Ultra-violet light has not been effective to date in producing mutations in 

 chickens. 



The Value of Starfish Meal in the Poultry Starting Ration. (Raymond T. 

 Parkhurst, in cooperation with Roy E. Morse and Francis P. Griffiths of the 

 Department of Food Technology.) The commercially produced meal made by 

 dehydrating starfish (Asterias Forbesi) can be satisfactorilj- used as a source of 

 protein and minerals in chick starting rations. 



