Recently, the Republic of Belarus has cultivated new species and varieties of lupine and pea and other grain-forage crops with a low content of anti-nutritional substances that can be used in repair bulls diets to improve their reproductive ability. Therefore, our studies in this area have a scientific and practical significance to improve the growth efficiency of repair bulls.

The aim of this work was to study the effect of the fractional composition of the protein on the growth rate and sperm indicators of repair bulls.

For the experiment there were chosen black-motley breed repair bulls with initial body weight of 365-369 kg.

Differences in feeding calves were that in the control group non-split protein level in the diet was below 10% of the highest standard. In the second experimental group, the content of non-split protein in the diet corresponded to the highest rate due to extruded pea and lupine, and flaxseed meal. The level of non-split protein in the diet of bulls III experimental group was higher than normal by 10% by increasing the amount of input into the extruded grain forage pea and lupine, and flaxseed meal.

Cum repair bulls are selected using standard tools and stuffed it for the taking. The quantity and quality of sperm production – according to the procedure adopted by the elevere.

Experimental diet consisted of grass-legume hay, silage mixed grass, grain forage, molasses. In addition to the diets of calves injected peas, lupine, sunflower, linseed cake. In the structure of the diet of steers in the control group took the hay
(% nutritionally) – 21, haylage – 31 grain forage – 38, sunflower – 6, syrup – 4 structure rations experimental animals took 22,5-21 hay, haylage – 31 -31, grain forage – 34-30, peas – 3-4.5, lupine – 2.5-3.5; lupine – 2.5-3.5; Linen cake – 3-6, syrup – 4-4.

The sugar-protein ratio in the diet of calves in group I was 0.86, in the II and III – 0.87 and 0.88, respectively. The average daily dry matter intake was at 9.1-9.3 kg. The concentration of metabolizable energy in 1 kg of diet dry matter, turned out to be a fairly high level – 9,7-9,9 no significant differences between the groups. Fiber content in dry matter was 21,5-21,9%.

The total protein increase in blood of the II experimental bulls group by 4%, and the total protein nitrogen – by 4-5%, while the young III experimental group, these figures increased by 6.5 and 7%, respectively.

Average daily gain in the control group bulls amounted to 971 g, and experimental increased to 992-1020 grams, or 2 and 5%.

By volume of ejaculate the II and III bull groups were superior to analogue group I by 11-14%, and the concentration of sperm – by 9-12%. The average number of frozen semen doses was 59-67.

Analysis of data on nutrient use efficiency and energy feed in experimental animals shows that the transformation of the feed energy into the energy of the best indicators of growth have showed groups II and III, in addition to receiving the diet peas, lupins and flax cake.

The amount of energy deposited in growth, in bulls groups II and III was 19.89 -20.81, or 4,1-9,0% more than in the I group.

Energy costs per 1 MJ, delayed in growth amounted in groups II and III, 4.47 and 4.40, or 4.5% lower than in controls. However, the best results were observed in the experimental group III bulls fed with diet containing non-split protein level above the norm by 10%.

Feeding repair bulls with 369-460,8 kg body weight with non-split protein rations by level 10% higher than normal increases the transformation of the exchange energy into live weight gain from 19.10 to 20.81 MJ or 9%, which increases the average daily gain 5% reduction in energy consumption and feed by 5% per unit of energy deposited in growth.

By volume of ejaculate III experimental group bulls were superior to the control group counterparts by 14%, and the concentration of spermatozoa in the ejaculate – 12%. The average number of frozen semen doses was 67%.

Thus, feeding repair bulls rations with non-split protein level of the corresponding norm (group II) increases the transformation of the exchange energy into live weight gain, which leads to greater average daily gain of 2% and a reduction in energy consumption of feed by 4% in the delayed growth. Use in feeding bulls diets with non-split protein level of 10% above normal (group III) enhances the transformation of energy into the exchange rate, which increases the average growth of 5% while reducing energy consumption by 5% of feed per unit of energy deposited in growth.

Key words: repair bulls, rations, non-split and split protein, blood, average daily gains, sperm production.