The method of evaluating the integral influence of the structure of the ration on the processes of digestion in the rumen of heifers

Abstract

Goal. To assess the influence of the integral indicator of the structure of the ration on the digestibility of nutrients in heifers. Methods. In the experiment, 2 heifers were used — with rumen and duodenal cannulas. One animal was fed a ration consisting of corn silage, oat hay, and compound feed; the second received only corn silage. To calculate the digestibility of nutrients in a complex stomach, the amount of chyme flow per day was determined. Balance experiments were performed with simultaneous sampling of rumen content, duodenal chyme, and faecal matter. The composition of the rations, the content of the gastrointestinal tract, and faecal matters were analyzed according to generally accepted methods. The weighted average size of feed particles was determined by manual sorting and dry sieving, and the selected biological samples were determined by wet sieving. Results. An inverse relationship between the size of the ration particles and the content of the digestive tract of heifers was established. The spectral characteristics of the particles of rumen content, chyme, and faecal matter depended on the composition of the ration: the fractional composition of the rumen content had two peaks — in the particle size range of 0–2 mm and 11–14.4 mm, and for chyme and faecal matter, a slight shift in the peak of large particles was observed in the side of decreasing size. The integral index of the structure was evaluated by the method of determining the average particle size and consumption of dry matter. Its value for the ration was 0.150–0.318, for rumen content — 0.031–0.060, for chyme — 0.004–0.005, and for faecal matter — 0.003 kg SR m/day. A significant difference in the digestibility of nutrients in the rumen with a change in the structure of the ration in case of some increase in the synthesis of microbial crude protein was not recorded. Conclusions. A methodological approach was developed to determine the integral indicator of the structure of feed, rations, the content of the gastrointestinal tract, and faecal matter by the product of the average particle size and the dry matter content of the sample. The structure of the diet was inversely related to the structure of the content of the gastrointestinal tract and faecal matter. Structural changes had no significant effect on the digestibility of the main groups of feed nutrients in the rumen for improving the conditions of microbial crude protein synthesis (p<0.05). A decrease in structure had a negative effect on the processes of visible fiber digestibility (it decreased by 2.9%), while it increased the digestibility of most nutrients by an average of 3.5%.