et al. (1955) have analyzed the effect of pyridoxine deficiency 
on the gonadotrophic content of the pituitary in rats and have 
found that the deficiency does not impair production of either 
F.S.H. or I.C.S.H. They suggest that the interference is either 
with the release or the utilization of these hormones. 
Pyridoxine may serve the same function in birds. Bird (1956) 
showed that the inhibitory effect of saponin in alfalfa meal 
can be inactivated by excess pyridoxine. 7 
Feeding diets deficient in minerals is another way to 
reduce egg production. Donovan et al. (1960) fed a diet to 18 
Single Comb White Leghorn hens which contained only 0.12 per cent 
calcium. During a fiveeday period, production dropped 9.6 per 
cent as compared with a six-week pre-experimental period, In 
two phosphorus studies, a diet containing between 0.18 and 0.19 
per cent phosphorus caused a decrease in production (0'Rourke 
et al., 1953), and a diet of 0.15 per cent supported only 45.3 
per cent production as compared with 69.8 per cent and 74.9 per 
cent production for 0.25 per cent and 0.35 per cent total 
phosphorus respectively (Crowley et al., 1961). Burns et al., 
(1952), stated that some unpublished data indicates that a 
potassium deficiency also decreased production. Sodium chloride 
below .19 per cent of the diet causes a lowering of production 
with sodium appearing to be the limiting factor according to 
Burns et al. (1952). Another study, however, has shown that a 
large quantity of sodium chloride, sodium sulfate and magnesium 
sulfate in the water will also cause significant reductions in 
egg production. 
A large number of drugs and other substances in feed 
lower or stop egg production. Polybor-3, which is borax, fed 
at the rate of 3 and 6 lbs, per ton as a house fly larvacide 
reduced egg production by 10 to 15 per cent, (Sherwood, 1959, 
and Tower et ale, 1960), and the insecticides, dipterex and 
diazinon depress both egg production and food consumption. 
(Ross et ale, 1960). 
Toxic-fat added to the diet reduced egg production to 
zero in 55 days (Dunahoo et al., 1959). When oats which had 
been fumigated with 64 per cent carbon tetrachloride, 29 per cent 
ethylene dichloride and 7 per cent ethylene dibromide at the 
rate of 1.5 cc. per pound were used in the diet, production was 
reduced to 37 percent versus 66 per cent when only 0.5 ec. level 
of fumigation was used (Caylor et al., 1960). Arasan, which 
4s 50 per cent tetra-methyl=-thiuram disulfide, used on carn 
and improved Ceresan, which is 5 per cent ethyl-mercury-phosphate, 
used on wheat decreased egg production. If corn made up a 1/3 
of the ration, then production dropped from 60-70 per cent down 
to 10 per cent in 2=3 days. If wheat made up 1/2 the ration, it 
dropped to 25 per cent (Heuser, 1956). | 
Some plant products are also inhibitory. Lithospermum 
injected at the rate of 120 mg., 100 mg., 60 mg., and 50 mg. for 
five days inhibited egg laying completely in three days. Ovaries 
60 
