Stadelman et al. (1950) showed that absence of supplementary 
vitamin D in turkeys also reduced hatchability. Hill et al. 
(1954) showed that the minimum level of riboflavin necessary 
in Leghorn's diet was 1.7 mg. per pound and that about 2.5 to 
3 micrograms per gram of yolk in the egg was required for 
normal hatchability. Ferguson et al. (1961) showed in turkeys that 
lack of riboflavin caused completely inhibited hatchability with 
high firsteweek mortality. Maw, in 1954, found in Single Comb 
White Leghorns a genetic equivalent to dietary riboflavin 
deficiency. These birds carried a recessive gene which made 
them unable to transfer the vitamin from the feed to the egg. 
Vitamin E at 2O mg. per pound of feed was necessary for maximum 
hatchability in turkeys (Scott et al., 1955 and Atkinson et al.. 
1961). Jensen et al. (1955) showed that feeding 2 per cent 
fish liver oil accentuated the vitamin E deficiency. On the 
basal diet he reported only 67 per cent hatchability, but 
addition of fish liver oil lowered this to 40 per cent. 
For mineral deficiencies, O'Rourke et al. (1953) 
showed that a low phosphorus diet, 0.18 to 0.19 per cent re- 
duced hatchability. Rogler et al. (1959) with an iodine de- 
ficient diet, and McCartney and Shaffner (1950) by feeding 
thiouracil at a level of 0.3 per cent showed similar results, 
but for different physiological reasons. In one case, there 
was no iodine for the thyroid to pick up in manufacturing 
thyroxine; and in the other case, the high concentration of 
thiouracil inhibited the thyroxine production. The end results 
were the same, however: the lowered metabolic rate resulted in 
slower growth and fewer chicks hatched. 
The following drugs or materials when added to the 
feed all adversely affect hatchability: (Some are known to enter 
the yolk; the site of action of others are not known) Toxic- 
fats and heated and aerated cottonseed o11 at a 5 per cent 
level (Naber et al., 1958); pure gossypol mixed with the diet 
at either 0.024 or 0.036 per cent levels (Heywang et al., 1950) 
(Bird, 1956); reserpine (in turkeys) at 2 ppm. (Greene, et al., 
1961); the antioxidant 2,5=-di-tertebutyl-hydroquinone at 0.25 
per cent (Heywang et al., 1958); arsanilic acid fed to turkeys 
continually from 10 to 12 weeks of age (Moore et al., 1954); 
NFm180 fed to turkeys at 0.011 per cent and 0,022 per cent 
(Smyth, et ale, 1959 and McCartney et al., 1960); and lastly, 
nicarbazin fed at levels of 0.005 per cent and 0.0125 per cent 
decreased hatechability by about 50 per cent while a level of 
0.002 per cent reduced hatchability by only 20 per cent (Sherwood 
et ale, 1956). Polin et al. (1956) found that the level in the 
yolk of 4,4° = dinitrocarbanilide, from feeding nicarbazin, had 
to be above 2 gamma per gram in order to influence hatchability. 
63 
