The effects of
dietary fat level, fat source, and
protein level on the growth response of broiler chicks were evaluated in two experiments with a factorial design. A higher level of
soybean oil (SO) (3.5 vs. .5%) in diets containing either 18.2 or 20.4%
protein significantly (P less than .05) counteracted the depressing effect of
monensin on feed intake and
weight gain in male chicks in the first experiment.
Dietary protein level did not significantly (P greater than .05) affect the response to
monensin, nor did
monensin affect feed to gain ratio. The higher SO level of 3.5% in diets containing 18.2%
protein reduced, at times significantly (P less than .05), the depressing effect of
monensin on feed and water intake, water to feed ratio,
weight gain, and the retention of dry matter and
nitrogen in female chicks in the second experiment. A similar higher level of
tallow resulted in less pronounced effects on most of the parameters.
Monensin supplementation did not affect dietary metabolizable energy content, but significantly (P less than .01) increased feed to gain ratio and the percent of fecal dry matter. It was concluded that the toxicity of
monensin to chicks might be alleviated by increasing dietary
unsaturated fat and
protein levels.