Experimental substantiation of new criteria for silage quality evaluation

Abstract

Purpose. To substantiate new criteria for evaluation of corn silage quality with bio-preservatives. Methods. Zootechnical method to determine feed digestibility in animal experiments. It is incorporated in amphorae of 1.8 tons of corn silage mass of the beginning of wax ripeness. The first amphora was without preservative, the second was with bio preservative No. 1 and the third one was with bio preservative No. 2. The silo of 3 amphorae according to the standard was evaluated. In all 3 amphorae, the silo was of good quality, but the digestibility of dry matter in the balance experiments on the rams was different. Results. The most commonly accepted criteria for evaluating silo quality are its pH value and the solids content. The high quality silo has a pH of water extract in the range of 3.6—3.9. Such pH values are created by the high content of lactic acid and low ammonia content. Under these conditions, the nutrient retention in the silage feed is the highest compared to other acidity parameters. Thus, under pH higher than 4.4 and dry matter content of 30 %, the fermentation in the silo process takes place by the proteolytic type and, as a result, butyric acid, amines and ammonia, not lactic acid, are formed. Due to the fact that butyric acid is much weaker than lactic acid and thus has a low preservative capacity, the silo is of poor quality. Therefore, high levels of ammonia, amines and butyric acid cause poor quality of the silo. High quality silo contains up to 20 % free acids (2/3 – lactic acid and 1/3 acetic acid). Our research has shown that silage packed with bio-preservatives based on lactic and propionic acid bacteria has a higher digestibility of nutrients than the same starting mass (raw material), which is ensiled without a bio-preservative. Lactic acid bacteria synthesize B vitamins (B1, B2, B5 and B7) and essential amino acids, and propionic bacteria further synthesize vitamin B12, forming mucus and giving the silage a specific, pleasant taste, providing better feed for animals, e.g. cows, substances, which is a consequence of the higher productive action of the feed. Digestibility of dry matter of silage, which was incorporated without a biological preservative, was at the rate of 53.9 %, and it was 8.8 % higher with bio-preservative No. 1. Studies conducted with an air-dry matter of 3 silos to obtain a suspension have provided the basis for evaluating bacterial preservatives for their ability to stimulate the growth of microbial protein in the silage. Conclusions. On the basis of the conducted researches new criteria for evaluation of corn silage quality were experimentally substantiated. Indicators of high-quality silage, namely, pH, total acidity, lactic, content of acetic and butyric acids and ammonia, include the digestibility of dry matter in animals, and the determination of bacterial protein as an important factor in the influence of lactic and propionic acid bacteria of bio-preservatives on the biological value of feed protein, which is a criterion for evaluating biological preservatives for the ability to stimulate bacterial protein gain in silage.