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0. B. COWEY AND J. R. SARQENT
been considered as nutritional entities (see later) and the fat components in the diet may need to be defined as explicitly as protein
components in experimental and practical diets. Of the three fats used
by Dupree the fatty acids of solid corn oil are intermediate in degree
of saturation between liquid corn oil and beef tallow ; whether or not
degree of saturation bears on protein sparing quality is not clear at this
time.
We may conclude that components of the diet which are used solely
for energy production promote utilization of food protein or have a
sparing action on its use. Data presently available are largely
descriptive and the mechanisms involved in this sparing action
require a penetrating study.
J . Growth promoting effects of anabolic steroids
and other compounds
Certain steroids promote nitrogen conservation and body weight
gain in mammals. These effects were first observed over 35 years ago
(Kochakian and Murlin, 1935) and since then these " anabolic "
steroids have been intensively studied both experimentally and
clinically. Testosterone and its derivatives are among the most active ;
in the normal animal they are androgenic, although efforts have been
made to synthesize derivatives which are without any masculinizing
side effects.
Growth promoting compounds have obvious significance for all
branches of animal production and studies on the anabolic effects of
some steroids on fish have been initiated. Hirose and Hibiya (1968a)
compared the growth promoting effect of intraperitoneal and intramuscular injections of several concentrations of 4-chlorotestosterone
acetate, methylandrostenediol and testosterone propionate in both
sexually active and inactive goldfish. Weight gains of chlorotestosterone treated fish were nearly double those of controls, the anabolic
effects of the other two steroids were less apparent-possibly because
of their very marked side effects. Some side effects resulted from
4-chlorotestosterone injection, most notably a suppression of gonad
maturation and a renotrophic action (hypertrophy of epithelial cells
and nuclei in the kidney tubule).
Chlorotestosterone was also shown to promote growth in rainbow
trout (Hirose and Hibiya, 1968b). Renotrophic effects were not very
marked but there was strong suppression of gonadal maturation.
Deposition of yolk in the oocytes was restrained and testicular cells did
not develop beyond the spermatogonium stage. It may be that chlorotestosterone blocks the release of gonadotrophins in the pituitary.
0. B. COWEY AND J. R. SARQENT
been considered as nutritional entities (see later) and the fat components in the diet may need to be defined as explicitly as protein
components in experimental and practical diets. Of the three fats used
by Dupree the fatty acids of solid corn oil are intermediate in degree
of saturation between liquid corn oil and beef tallow ; whether or not
degree of saturation bears on protein sparing quality is not clear at this
time.
We may conclude that components of the diet which are used solely
for energy production promote utilization of food protein or have a
sparing action on its use. Data presently available are largely
descriptive and the mechanisms involved in this sparing action
require a penetrating study.
J . Growth promoting effects of anabolic steroids
and other compounds
Certain steroids promote nitrogen conservation and body weight
gain in mammals. These effects were first observed over 35 years ago
(Kochakian and Murlin, 1935) and since then these " anabolic "
steroids have been intensively studied both experimentally and
clinically. Testosterone and its derivatives are among the most active ;
in the normal animal they are androgenic, although efforts have been
made to synthesize derivatives which are without any masculinizing
side effects.
Growth promoting compounds have obvious significance for all
branches of animal production and studies on the anabolic effects of
some steroids on fish have been initiated. Hirose and Hibiya (1968a)
compared the growth promoting effect of intraperitoneal and intramuscular injections of several concentrations of 4-chlorotestosterone
acetate, methylandrostenediol and testosterone propionate in both
sexually active and inactive goldfish. Weight gains of chlorotestosterone treated fish were nearly double those of controls, the anabolic
effects of the other two steroids were less apparent-possibly because
of their very marked side effects. Some side effects resulted from
4-chlorotestosterone injection, most notably a suppression of gonad
maturation and a renotrophic action (hypertrophy of epithelial cells
and nuclei in the kidney tubule).
Chlorotestosterone was also shown to promote growth in rainbow
trout (Hirose and Hibiya, 1968b). Renotrophic effects were not very
marked but there was strong suppression of gonadal maturation.
Deposition of yolk in the oocytes was restrained and testicular cells did
not develop beyond the spermatogonium stage. It may be that chlorotestosterone blocks the release of gonadotrophins in the pituitary.