The Utilization of Rye by Growing Chicks as Influenced by Autoclave Treatment, Water Extraction, and Water Soaking

Abstract

Three experiments were conducted with growing chicks to study the effect of autoclave treatment, water extraction, water soaking, and antibiotic supplementation on the nutritional value of rye grain. Experiment 1 showed that the antinutritional factor(s) in rye grain was not destroyed by autoclaving. This treatment for 10 or 30 min, respectively, depressed feed utilization by 9 and 14% in the rye fed chicks and by only 2 and 4% in the wheat fed birds because of reduced digestibility of all nutrients. The detrimental effect of rye grain was partly overcome by increased feed intake. Experiment 2 demonstrated that rye grain contains a water-soluble, sticky, and hydroscopic factor forming highly viscous aqueous solutions. The addition of this factor to a wheat-based diet depressed chick performance to that obtained from feeding extracted rye because of the factor's interference with palatability of the feed and the digestion and absorption of all nutrients including fat and most of the individual amino acids. Extraction of rye twice improved chick performance and the digestibility of all nutrients, but all of these criteria were still inferior compared to those of wheat-fed chicks. The residual antinutritional activity of extracted rye was attributed to the partially insoluble nature of this factor. Chick performance was also improved by penicillin supplementation of diets containing rye, extracted rye, or water extract. In Experiment 3, chick growth and feed utilization were markedly improved with increasing soaking time (in the presence of an antimicrobial agent) or nonautoclaved rye, but soaking of autoclaved rye had no effect. The improvement of chick performance was attributed to a sharp depression with time of the viscosity of a water extract from nonautoclaved rye. This suggested the degradation of the antinutritional factor(s) by endogenous enzymes in the nonautoclaved water-soaked rye. It may be concluded that autoclave treatment protects the antinutritional factor against the inactivation that occurs when rye is soaked in water. Inactivation of the soluble factor is also associated with a decrease in the viscosity of an extract of rye. The factor also appears to be located in both the soluble and insoluble portion of the grain and depresses the retention of all nutrients.