Study of the kinetic regularities of the grain extrusion process in the production of highly digestible feed with protected protein for cattle

Abstract

The problem of developing of highly digestible compound feeds with protected protein for cattle is due to the specifics of the gastric tract of cows and the peculiarities of protein assimilation. Due to the importance of preliminary moisture-heat treatment of grain for the subsequent course of the extrusion process, it was carried out by steam at a pressure of 0.6 МРа before moistening the feed to a humidity of 17–20% and heating to a temperature of 70–80° C. It is established that heat treatment has a significant effect on the carbohydrate complex of grain: heating it at high temperatures causes the destruction of starch, accompanied by the formation of easily soluble carbohydrates, which has a positive effect on the digestibility of feed. The kinetic regularities of the processes of moisture-heat treatment, grinding and extrusion of grain in the production of highly digestible feed with protected protein for cattle were studied. The degree of dextrinization and the digestibility of starch increased with the heating temperature of corn and its mixtures with wheat up to 100–110° C, when the performance of the extruder was 300–320 kg/h, the digestibility of starch extruded corn and grain mixture is increased to 85 and 68 mg of glucose per 1 g of the product (hereinafter mg/g), respectively. For wheat, this indicator is lower and, accordingly, is 50 mg/g. When heated during the extrusion of corn to a temperature of up to 120–140° C, the digestibility of starch was 100–110 mg/g, and for the grain mixture – 80–83 mg/g. At this temperature, the digestibility of the starch of extruded wheat corresponded to 60–65 mg/g. The optimal moisture content of feed in the process of extrusion for the purpose of forming pellets is 18%. Studies of the extrusion effect on the carbohydrate complex of processed feed have shown that the destruction of starch in the extruded product increases. Thus, the content of soluble carbohydrates increases by 27–32%, and the digestibility of starch increases twice in extruded feed compared to unprocessed.