66 MASS. EXPERIMENT STATION BULLETIN 441 



concerned. A special study is being made ot the value of progeny testing in breed- 

 ing for high fecundity, and of the possible effect of air temperature on egg size in 

 Rhode Island Reds. 



Early sexual maturity, very low broodiness, and high persistency are well 

 fixed in the flock, but intensity and incidence of winter pause remain variable. 

 Efforts are being made to reduce variability in egg production by a search for 

 inherited factors operating. 



A Study of Fertility Cycle in Males. (F. A. Hays.) Synthetic thyroxin was 

 used in the spring of 1947 to activate males of various ages to higher fertility. 

 Artificial light was also tested. Results showed that the hormone was not quite 

 so effective as artificial light. Cockerels have not been affected by any agents 

 used. 



The complete report ot this and previous 3'ears' tests is now in press. 



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

 project was completed in the fall of 1946. Colorimetric analysis of intensity of 

 soluble feather pigment suggests that less intense pigmentation depends on sev- 

 eral dominant genes. A complete report is ready for publication. 



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



High and low hatchability lines have been developed through the third genera- 

 tion, but have not yet been carried long enough to be definitely established. A 

 search for lethals responsible for low hatchability and abnormal sex ratios has 

 not been very fruitful as yet. Preliminary evidence indicates, however, that sex 

 differences in embryonic mortality rates pla\' considerable part when secondary 

 sex ratios are abnormal. 



Breeding for High and Low Incidence of Internal Defects in Hen's Eggs. 

 (F. P. Jeffrey and C. E. Walker.) Strains of Rhode Island Reds have been bred 

 which differ significantl}' in incidence of meat spots in their eggs. Continued 

 selection will be practiced to further differentiate these strains. There is a small 

 but significant association between incidence of meat spots and degree of shell 

 color, the eggs with darkest shell color tending to carry more meat spots than 

 those with the lightest shell color. Egg shell color varies widely in these strains. 



Breeding White Plymouth Rocks for Eggs and Meat. (F. P. Jeffrey.) A 

 strain of White Plymouth Rocks has been developed which is pure for the Colum- 

 bian pattern; that is, males of this strain when mated with Rhode Island Red or 

 New Hampshire females give red pullets and "Columbian" males. 



Hatchability Factors in Products of Vegetable Origin-Distillers' Dried Solubles 

 as Supplements to Soybean Meal Rations. (Marie S. Gutowska.) Two types 

 of basal rations were used in making up the eight experimental rations. Type I 

 consisted largely of corn and soybean meal supplemented with methionine and 

 choline and small amounts of alfalfa meal. Type II contained less soj'bean and 

 corn meal but included also wheat bran and oats. Mineral and vitamin supple- 

 ments were added to both types on an equal basis. Soludri regular and Soludri 3N 

 (Distillers' Dried Solubles), both fermentation products of vegetable origin, 

 were the materials tested for their value as supplements. 



The results demonstrated clearly that, whereas the basal Type I ration main- 

 tained hatchability at a low level of 49 percent of fertile eggs, the hatchability 

 was improved considerably (36 percent) when a supplement of 3N Soludri was 



