Interaction of dietary protein level on dose response relationships during aflatoxicosis in young chickens

It is well known that the effect of aflatoxin is enhanced by a low protein diet, but whether this is associated with a lower apparent minimum effective dose, increased slope of response curves, or both has not been investigated previously. Aflatoxin at 12 dosages ranging from 0 to 2.34 micrograms/g of feed was fed to eight groups of 10 young chickens per treatment consuming a 10.00 or 12.75% protein diet for 3 weeks. The body weights, liver weights relative to body weights, and total lipid content of the livers were determined. Mathematical models were fitted to the data and from the appropriate equations the dose-response curves were predicted as continuous functions of aflatoxin concentration. A quadratic polynomial fit body weight data on the 12.75% protein diet whereas a plateau-linear model fit body weight data on the 10.00% protein diet. This implies that in a low protein diet aflatoxin affects only one of the factors controlling growth. Plateau-linear models fit liver relative weight and liver lipid content data on both 10.00 and 12.75% diets. For both variables the lower protein diet decreased the apparent minimum effective dose and increased the positive slope of the linear response. The apparent minimum effective doses (micrograms of aflatoxin per gram of feed) in this experimental system were calculated from the modeling approach to be 1.21 and 2.00 for body weight, 1.08 and 1.65 for liver lipids, and 1.45 and 2.34 for liver relative weight in 10.00 and 12.75% protein diets, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)