Soy Flour as a Source Protein for Baby Pigs

Soy flour as a source of protein for piglets 3 weeks of age has been investigated under carefully controlled conditions by feeding liquid soy flour diets, hourly, with the aid of an automatic feeding device (Autosow). The average daily gains and dietary efficiencies that have been observed in these experiments were obtained with diets that were free of antibiotics. Average daily gains (kilograms) and dietary efficiencies (kilogram dry matter per kilogram gain) were .37 and 1.40 (untreated soy diet, 25% protein calories); .39 and 1.50 (acid-treated soy diet, 25% protein calories); and .37 and 1.15 (non-fat milk solids, 25% protein calories). Experiments comparing different soy flour diets containing 15% and 25% calories (isoca-loric) showed that there was no difference in the daily rates of gain (.34 and .35 kilogram/day, respectively) and efficiency of utilization (1.36 vs 1.37 kilogram diet/kilogram gain, respectively) in these two diets. Further experiments designed to determine the minimum concentration of protein required to promote growth rates comparable to the 15% protein caloric diets used soy flour diets containing 15%, 11% and 7% soy protein calories; the average daily gains (kilograms) for these diets were .43, .44 and .31, respectively. The dietary efficiencies were 1.32, 1.35 and 1.90, respectively. These data show that a diet containing 11% of the total calories as soy flour protein is sufficient protein calories for pigs 3 weeks of age and reared under the conditions in which an automatic feeding device is employed.