Efficiency of using boluses based on microelements in feeding Simmental cows in Yakutia

Purpose: to study the efficiency of using a microelement-based bolus to improve feed digestibility in Simmental dairy cows in Yakutia.
Materials and methods. Three groups of animals were formed, each with three heads, based on the pair-analogue principle, taking into account age and live weight. Cows in the 1st experimental group received the feed additive "Calcitop Bolus" at a dose of 1 bolus per head once during lactation and the mineral premix "Dar Velesa". Cows in the 2nd experimental group received only the feed additive in the form of a bolus. The 3rd group was the control. During the entire scientific and economic experiment, in the stall period, the experimental animals of all groups received a balanced diet in accordance with the detailed feeding system. The bolus was administered to dairy cows using a special applicator. The analysis of feed, its residues and animal feces was studied using near infrared spectroscopy on a Spectra Star 2200. The digestibility coefficients of nutrient diets were calculated based on the ratio of the amount of digested nutrients to those consumed and expressed as a percentage. The nutritional value of the diets was determined based on the chemical composition and digestibility coefficients. 
Results. Feeding the feed additive in the form of a bolus to Simmental cows made it possible to balance the diets for missing nutritional elements and improved the palatability of the main feeds during the stall period. It ensured normal development and increased the digestibility of nutrients in the feed. Thus, the digestibility of nutrients was higher in the cows of the 1st experimental group, with a high level of digestibility compared to the control and 2nd experimental groups was established for dry matter by 3,2 and 0,7 %, organic matter by 1,2 and 0,5 %, crude protein by 1,4 and 0,5%, crude fat by 1,4 and 0,7 %, crude fiber by 1,9 and 0,4 % and NEF by 4,4 and 3,5 %. The digestibility coefficients of dry matter in cows of the 1st experimental group were higher by 1,41%, organic matter — by 1,14 %, crude protein by 5,25 %, crude fat by 0,82 %, crude fiber by 2,56 % and NEF by 0,43 % (p<0,95). Good absorption of calcium and phosphorus was noted in all groups.

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