ANNUAL REPORT, 1942 55 



DEPARTMENT OF POULTRY HUSBANDRY 

 R. T. Parkhurst in Charge 



Broodiness in Poultry. (F. A. Hays.) Results of crossing strains over a 10-year 

 period confirm the h^'pothesis that two dominant complementary autosomal 

 genes, A and C are necessary to produce the broody instinct in Rhode Island Red 

 females. Extreme care in crossing strains is necessary to avoid bringing together 

 these two genes. 



The attempt is still being made to develop a non-broody strain of Rhode Island 

 Reds through progeny testing. The major objective yet to be accomplished is to 

 discover whether or not both genes A and C can be completely eliminated by this 

 method. 



A Genetic Study of Rhode Island Red Color. (F. A. Hays.) Two lines of exhi- 

 bition-bred Rhode Island Reds are being developed; one selectively bred for early 

 sexual maturity, and the other for late sexual maturity. Complete plumage 

 color records are made on all birds, and females are trapnested for a full year to 

 get their performance record. Feather samples are also taken at sexual maturity 

 from all birds and these are being studied for pigment distribution. 



Crosses between Rhode Island Reds and Buff Orpingtons indicate that the 

 extension factor E for melanin pigment is not present, but that Buff Orpingtons 

 are essentially the same as Rhode Island Reds in that the e factor permits the 

 development of some black pigment in neck, wings, and tail. Fi hybrids are 

 intermediate in general plumage color, but the lipochrome pigment in skin, beak, 

 and shanks is inhibited so that the color is white. 



The Effectiveness of Selective Breeding in Reducing Mortality in Rhode 

 Lsland Reds. Cooperative Project with the Regional Poultry- Research Labora- 

 tory of East Lansing, Michigan, and the Department of Veterinary Science. 

 (F. A. Hays.) Seven generations have been carried through to the age of 18 

 months to study the effectiveness of selective breeding in reducing mortality in 

 one line and increasing mortality in another. The loss from cannibalism in the 

 females of the low mortality line was double that in the high mortality line. 

 Such losses distort the results, but there was no indication that selective breeding 

 with small numbers is effective In reducing the mortallt}- rate of males and females 

 from the ordinary diseases and disorders. 



Losses during this period were produced by a number of disorders but there 

 were no acute outbreaks of disease. In many cases more than one disorder ap- 

 peared In the same individual and the primary cause of death was not determined. 



Genetic Laws Governing the Inheritance of High Fecundity in Domestic 

 Fowl. (F. A. Hays and Rubj- Sanborn.) At the present time particular attention 

 Is being given to the establishment of genetic uniformity in Intensity of laying. 

 Intensity Is a complex character which has an important relation to egg size. 

 Egg size has reached a satisfactory level, but Intensity is still highly variable 

 and there Is considerable difficulty In combining large egg size with high intensity. 

 The incidence and duration of winter pause have also received special attention. 

 In other characters affecting egg production there Is a satisfactory degree of 

 uniformity In the flock. 



A Study of Fertility Cycles in Males. (F. A. Hays.) In addition to the histo- 

 logical study of stages of spermatogenesis In males of different ages and at differ- 

 ent seasons, still under way, attention has been given to fertility tests of males in 

 natural matings throughout the summer. During this period the oldest male 

 (36 months old) declined In fertility from 81 percent to 45 percent. The 24- 



