ANNUAL REPORT, 1945-46 63 



ing males. A limited life span in birds also adds to the difficulties. Data indi- 

 cate that females with broodiness deferred beyond the first laying year sometimes 

 produce daughters that exhibit the broody instinct in their first year. Hens that 

 only cluck without cessation of laying may transmit broodiness. The most 

 recent data indicate that broody behavior often appears in the most intense 

 winter layers. 



The last complete generation was hatched in 1944 and completed their first- 

 year record in 1945. Of the 66 pullets housed, 51 completed a full year. Only 

 one exhibited the broody instinct, and that by a single period. These females 

 are being tested for deferred broodiness. 



Effectiveness of Selective Breeding to Reduce Mortality. (Regional Poultry 

 Research Laboratory and Departments of Veterinary Science and Poultry Hus- 

 bandry, Massachusetts Agricultural Experiment Station, cooperating.) Results 

 of three generations of inbreeding to produce high and low mortality lines, with 

 mortality rate the sole basis of selection, will not be completed until November 

 1946. The data indicate a significant difference between the two lines. One dis- 

 turbing feature is that the mortality rate in the low line always exceeds the mor- 

 tality rate in the control line. Complete results are not yet available. 



Genetic Laws Governing the Inheritance of High Fecundity in Domestic 

 Fowl. (F. A. Hays and Ruby Sanborn.) Particular attention has been given to 

 methods of selecting breeders to raise the level of production. A seven-year 

 study just completed (now in press) indicates that annual egg production is a 

 very unsatisfactory' criterion of the probable breeding value of hens in improved 

 flocks. 



Intensity of laying at all seasons of the year stands out as of highest importance 

 in the station flock of Rhode Island Reds at the present time. Methods of 

 measuring intensity and further evidence of its mode of inheritance are receiving 

 special study. 



At present, raising the average egg production of all daughters from the dif- 

 ferent families above 230 eggs averaging about 25 ounces to the dozen seems to 

 depend upon higher intensity and greater freedom from winter pause. 



Fertility Cycles in Males. (F. A. Hays.) Sex hormones have not proved 

 effective in increasing natural fertility of old males in midwinter. The value of 

 artificial light for this purpose will be studied further. 



A Genetic Analysis of Rhode Island Red Color. (F. A. Hays.) This project 

 has been concluded. General results indicate recessive genes controlling dark 

 pigmentation. 



Secondary and Adult Sex Ratio in Relation to Hatchability. (F. A. Hays.) 

 Further data on sex ratio have been secured on high and low hatching lines. 

 Sex has been recorded on dead embryos sufficiently advanced and upon all dead 

 chicks up to sexual maturity. The two lines differ greatly in hatchability, and 

 possible factors underlying this difference are being studied. 



Supplementary Nutritional Factors for Distillers' By-Products. (F. P. Jef- 

 frey, W. S. Ritchie, G. L. Woodside, and J. W. Kuzmeski.) The use of distillers' 

 b\'-products in poultry breeding rations has received continued study, with 

 special emphasis on the factor or factors in fish meal which have a supplementary 

 value for hatchability. In a repeat trial, the use of 1.25 percent of fish meal as 

 a supplement to the negative control gave disappointing results. The current 

 trial shows that 2.50 percent red fish meal and 2.00 percent liver extract give 

 equally good hatchability when supplementing the negative control. 



