were reduced from a control size of 59.4 ems. to 11.5 ems. This 
material has a definite effect on the pituitary (Zeller e ale, 
1958). Ground Crotalaria seed mixed with the feed at 0.2 per 
cent, 0.1 per cent and 0.05 per cent levels reduced production 
from 60 per cent to zero in 19 days, 2 per cent in six weeks 
and 20 per cent in six weeks in the three groups, respectively, 
in White Leghorn hens (Caylor et al,, 1961). Feeding alfalfa 
saponin extracted from alfalfa at 0.4 per cent level or 0,26 
per cent saponin supplied by sun-oured alfalfa meal at the 20 
per cent dietary level both depressed production considerably. 
Recovery was rapid after discontinuation of the saponin 
(Heywang et al., 1959). Atropine and SKG-501 have been shown 
to block ovulation in the hen (Zarrow and Bastian, 1953; Gaunt 
et ale, 1961). 
Greene et al. (1961) has found that levels of reserpine 
which are safe for chicken breeders have adverse effects on 
turkey and duck breeders. Two ppm. for turkeys markedly re- 
duces production, but not until about the third month of laying. 
O.5 ppm. maintains dueks at a low level of production, but 2 
ppm. and higher completely inhibits production. Feeding the 
antioxidant 2,5-di-tert-butyl-hydroquinone at levels of 0,25 
per cent reduced production, and 0.075 per cent gave borderline 
results (Heywang, et al., 1958), Administration of sulfamerazine 
in the feed at a 0.5 per cent concentration seriously reduced 
production, but 0.25 per cent levels did not (Riedel, 1950). 
Amprolium fed to hens at levels of 0.4 per eent and 0.8 per cent 
reduced feed intake to 45 per cent and 17 per cent of normal 
and egg production to 20 per cent and zero, respectively, by 
the third week (Polin, 1960). Sherwood et al. (1956) showed 
that Nicarbazin at a level of 0.0125 per cent slightly inhibited 
and at 0.07 per cent completely inhibited production in about 
ten days. The hens returned to production in about the same 
length of time after being removed from the drug. Weiss et al. 
(1960) showed that onset of egg production can be delayed by 
Nicarbazin. Three histomonastatic agents have been shown to 
reduce production at various levels. Moore et al. (1954) 
states that arsanelic acid fed to turkeys continually starting 
at 10 or 12 weeks of age reduced production. Moreng and Bryant 
(1956) showed that when 4-nitrophenylarsonic acid is added to 
drinking water at the recommended level, one pound per 160 
gallons, it reduced production from a control level of 74 per 
cent to 68.1 per cent. Pino and Hudson (1953) showed that feed- 
ing Enheptin to 13-week-old White Leghorn pullets for three 
weeks delayed sexual maturity by five weeks. Ten weeks were re- 
quired to recover from the drug. Continuous treatment at 0.05 
per cent level completely prevented sexual maturation. Pino 
(1955) inhibited egg production in laying hens with 0.10 per 
cent Enheptin within 7 to 10 days. Many of the birds went into 
a molt. After removal of the drug, production began in two 
weeks and was back to normal in six weeks, It has been shown 
that Enheptin selectively inhibits gonadotropic hormone activity, 
but does not affect thyrotropic activity (Pino et al., 1954). 
61 
