Comparisons of sorghum grain (milo) and maize as the principal cereal grain source in poultry rations

Synopsis

Three trials were performed with chicks from 5–8 to 22–29 d of age in order to compare the relative content of available sulphur amino acids (SAA) in maize and in milo grains, and to determine whether or not milo was a poorer source than maize in any additional amino acid. The cereal grains were substituted for each other on an isonitrogenous basis in grain‐soyabean meal diets, their crude protein content ranging from 16–6 to 17–8 per cent, and these diets were control‐fed in uniform quantities. The maize and milo diets of each trial were supplemented with three common levels of DL‐methionine, and with a fourth level which was calculated to be in excess of the SAA requirement. The relative available SAA content of the grains was estimated by using the regression equations for the best fitting lines to calculate the amounts of added methionine required with the two diets to obtain a certain common weight gain. The difference between these two quantities was then related to the dietary cereal protein.

In all trials linear graded responses were obtained to increments of DL‐methionine, with both maize and milo diets, and the differences in chick performance between these two dietary cereals were eliminated once methionine supplementation was high enough. Thus, under the conditions of this study, SAA were the first and only limiting amino acids for both types of diet.

The calculated differences in SAA between maize and milo protein were 1.53, 1.31 and 0.96 percentage points for trials 1.3, respectively. Since milo protein thus contained, on an average, 1.27 percentage points less available SAA than maize protein, which can be assumed to contain 3–89 per cent SAA, the estimated available SAA content of milo protein was 2.62 per cent.

Notes

Contribution from The Volcani Institute of Agricultural Research, Bet Dagan, Israel. 1970 series no. 1704‐E.