The Improvement of protein diet standards for breeding bulls

Abstract

The research was conducted in 3 groups of rearing bulls aged 12–18 months, with an average initial live weight of 363–367 kg. The amount of non-degradable protein in diet of rearing bulls of the control group was lower by 10 % of the accepted standard. The second experimental group corresponded to the accepted standard due to extruded peas, lupine and flax meal.The level of non-degradable protein in III experimental group was above the standard by 10 %. The research helped to determine that experimental groups of bulls that consumed food with the level of non-degradable protein according to the standard and 10 % higher in the rumen contenthas an increased level of total nitrogen by 5.1 % and 5.5 % and protein – by 7.5 and 8.2 % respectively. A significant reduction in the amount of ammonia in the rumen of experimental animals was determined by 21 (P<0.05) and 24.0 % (P<0.05), respectively, which indicates the decrease in protein degradability and improvement of its use by microorganisms for protein synthesis. Animals of II and III experimental groups consuming food with higher levels of non-degradable protein digested feed nutrients better. Thus, digestibility of dry and organic substances and protein significantly increased by 6.4 and 6.9; 6.4 and 7.1; 5.6 and 5.5 %. There is a tendency to increase of digestibility of fat, fiber and BEV. As a result of the analysis of the morphological and biochemical composition of blood, it was determined that there were no significant differences in all of the studied parameters, they all ranged within the physiological standard. However, there was an increase of total protein by 4.0 %, total and protein nitrogen – by 4.0–5.0 % in bulls’ blood of the II experimental group, while in young animals of III experimental group these indicators increased respectively by 6.5 and 7.0 %. The research has shown that the average daily weight gain of the bulls in control group was 980 g, and in the experimental ones it increased to 1009–1029 g or by 3.0 and 5.0 %. As for the volume of ejaculate, bulls of II and III groups surpassed their coevals of group I by 11.0–14.0 %, and by semen concentrations – by 9.0–12.0 %. The energy in weight gain of bulls of II and III experimental groups ranged 19.9–20.8 MJ, or 4.1–9.0 % and was higher compared to group I. The transformation of metabolizable energy of diet into body weight gain increased from 21.6 % (control) to 22.4– 22.6 %. The energy spent on diet per 1 MJ for weight gain decreased from 4.6 MJ (control) to 4.4–4.5 MJ or by 4.0–5.0 %. However, the best results were observed in young animals of III experimental group, who received diets with the level of non-degradable protein in the amount of 10 % above the standard. Key words: calves, diet, feed, degradable protein, non-degradable protein, rumen digestion, performance.