Genetic fach)rs ina\ coiitiiltute' to the inciflence of caiuiiltalism. Weaver 

 and Bird 11934) stated that the li<>lil breeds of the Mediterranean class 

 were much more susceptible to the vices of cannibabsm than the heavier 

 breeds of the American and Asiatic classes. In an unpubHshed summary of 

 three year's results in the New Ham|)shire Broiler Test, it was found by 

 the author that crosses containing Cornish blood were more prone to canni- 

 balism than were most of the pure breeds. 



Studies in respect to light intensity are limited in the literature. Most of 

 them are concerned with reproductive activity rather than the factors con- 

 sidered in this study. However, the i)ossible relationship between repro- 

 ductive activitx and feather picking should not be overlooked. Bissonnette 

 (1931) found that light from bulbs varying in strength from 10 to 60 watts 

 was capable of inducing progressive testis changes in starlings. However, 

 the effects produced were not of the same magnitude and the rate of ac- 

 celeration of gtMininal activity was not the same with different intensities 

 of added light. Burger (1939) in studies with light intensities in wild birds 

 concluded that gradually increased light intensity, when the light was ad- 

 ministered over da\-lengths which in themselves did not produce sperma- 

 togenesis, were incapable of testicular stimulation. Nicholas and co-workers 

 (1941) studying light intensities ranging from 0.5 to 38.0 foot candles at 

 a central point in the working area, and from to 27.0 at a central point 

 on the roosting perches in laying hens, found that intensity had no effect 

 on the degree of reproductive response. Shutze and co-workers ( 1960) 

 found that growth rate in broilers was the same at light intensities of 1 

 or 3 foot candles. 



Clegg and Sanford (1951) exposed chickens to alternate six-hour periods 

 of light and darkness and found that they were 66 grams heavier at six 

 weeks of age than chickens exposed to alternate periods of 12 hours of 

 light and darkness. When the periods Avere only two hours in length, the 

 weight differences were even greater. They suggested that the shorter in- 

 tervals of light and darkness prevented the chickens from taking excessive 

 exercise; therefore, the nutrients were used for growth rather than being 

 dissipated. Lamoreux (1943) found that the gains in the body weight of 

 domestic fowl were greatest when the daily period of light was inadequate 

 for the maximum stimulation of reproduction. Moore ( 1957) grew broiler 

 type birds from one day to eight weeks with exposures of 6. 12. 18 and 24 

 hours of total light per day. The results indicated that up to 3 or 4 weeks 

 of age the chicks grew faster with continuous light and that less light was 

 needed as thev neared 8 weeks. Better growth also was obtained when light 

 was applied in 4 or 6 periods per day instead of 1 period. Shutze and co- 

 workers (1960) also found that body weight gain of birds exposed to con- 

 tinuous incandescent light was markedly superior to that of birds exposed 

 to other lighting regimes. 



In respect to the influence of light upon feathering condition, Moultrie 

 and co-workers (1954) found that chicks reared from 6 to 10 or from 6 

 to 12 weeks of age under continuous light had fewer undesirable body 

 feathers than birds reared during that time under 5. 10. or 15 hours of 

 daily light. Moultrie and co-workers (1955) found a relative absence of 

 })infeathers at 24 weeks of age in turkeys restricted to 10 hours of light 

 daily compared to those receiving 24 hours of light daily. 



Experimental work concerned with the interaction effect of light in- 

 tensity and such factors as floor space (»r form of feed is extremely limited. 



