14 MASS. EXPERIMENT STATION BULLETIN 316 



GENERAL SUMMARY 



Exhibition stock and production stock and their hybrid offspring were com- 

 pared in fecundity characters, characters related to fecundity, and egg produc- 

 tion; also in plumage color, shade of under color, and the occurrence of smut. 



Compared with the production-bred stock, the exhibition stock used were 

 characteristically late maturing, low in intensity, good in egg weight, low in 

 hatchability, low in broodiness, low in persistency, low in mortality, and low in 

 egg production. 



In surface plumage color the exhibition stock showed about 70 per cent meeting 

 standard requirements and about 30 per cent classed as dark or medium in color. 

 The production stock had no standard-colored birds, very few dark red, and the 

 majority were either medium or light red in color. Practically all exhibition 

 birds ranked as dark or medium in under color, while all production stock ranked 

 as light or medium. Half of the exhibition males and about one-fifth of the 

 females carried smut in under color. Very few production birds showed smut. 



The study of the hybrid offspring obtained from the various matings yielded 

 the following conclusions: 



1. Crossing the two lines gave somewhat diverse results with respect to 

 fecundity traits in reciprocal crosses. When the production stock was used 

 for the male parent, the progeny were superior to those from the reciprocal cross, 

 and such Fi hybrids gave slightly greater egg production during the year. 



2. Segregation in the F2 generation gave a high percentage of late-maturing 

 birds, more low-intensity birds, more individuals with winter pause, more broody 

 birds, decreased persistency, and increased mortality. Egg production was 

 decidedly lower than in the checks. 



3. Back crossing either Fi or F2 females with production males raised the 

 egg production to near the level of production-bred birds. 



4. In surface plumage color the Fi generation was essentially intermediate 

 between standard and production color, but the hybrids from exhibition mothers 

 were decidedly darker in color than those from the reciprocal cross. 



5. Lighter shades of surface color appear to dominate the darker shades. 



6. The surface color may be restored to the F] medium color by back cross- 

 ing either Fi or F2 females on exhibition males. The development of a line 

 of birds with standard surface color from such crosses would be exceedingly 

 difficult. 



7. Dark surface and dark under color were rather intimately associated. 

 Light modifiers for under color seemed to dominate, and there was some evidence 

 of sex-linked modifiers. 



8. Smut was more common in the male sex. Smut in the females was most 

 likely to be associated with the lighter shades of surface color. There was some 

 evidence that smut tends to be associated with dark surface color in males. 



9. The inheritance of smut depends in part upon sex-linked dominant genes. 



10. Smut tends to lighten the shade of red pigment in feather fluff. 



11. Lighter shades of red in under color appear to be governed by dominant 

 genes. 



12. By crossing light-colored production-bred Rhode Island Reds with exhibition- 

 bred birds, followed by careful matings, a flock may be built up with rather uni- 

 form medium red plumage color and high egg production. 



