Efficiency of different variants of commercial crossing of beef cattle breeds of Russian selection
The article presents the results of studying the efficiency of two- and three-way crossing of Kalmyk cows (Kalm.) with Russian poll bulls (Rus.Poll) and Kazakh white-headed (Kaz. white) breeds. In the І group purebred bulls of Kalmyk breed were selected, in the ІІ - hybrids with genotype ½ Kalm.×½ Kaz. white, in the III - with genotype ½ Kalm.×½ Rus. Poll, in the IV - with genotype of ¼ Kalm.×¼ Rus. Poll×¼ Kaz. white and in the V - with genotype of ¼ Kalm.×¼ Kaz. white×½ Rus. Poll. In the course of studies it was established that hybrid bulls of the ІІ, ІІІ, ІV and V groups exceeded in live weight the purebred peers from Group I in all age periods. At the age of 16 months they had a live weight more than purebred peers respectively by 6.80; 5.79; 10.50 and 7.40 % (P>0.95). At the same time, sons of Kazakh white-headed bulls obtained in the three-way crossing (Group IV) exceeded two-way hybrids (Group II) by 1.34 % in live weight at the age of 16 months (P>0.95). Similar trend has been established for groups of sons of Russian Poll bulls. Upon the control slaughter hybrid bull carcasses were more massive than from purebred peers by 6.04-11.85 %. Weight of three-way hybrid carcasses in comparison with two-way was more by 2.32 % for Kazakh white-headed bulls and by 3.56 % for Russian Poll breed (P>0.95). Mean sample of carcasses’ flesh of hybrid bulls contained protein more than of purebred peers by 0.37; 0.67; 0.60 and 0.84 % (Р>0.95), while the fat content was less respectively by 0.59; 0.42; 0.39 and 0.14 % (P>0.95). The meat of the hybrid bulls had a higher biological value and optimal fractional protein composition. In the body of hybrid bulls, in comparison with purebreds, bioconversion of energy and protein of fodder into energy and protein of the flesh proceeded more intensively. They had higher conversion ratio of protein than purebred peers by 0.2-0.8 %, of energy - by 0.4-0.9 %. Profitability level of beef production obtained from hybrid bulls was higher than that of purebred peers by 9.4-15.5 % (P>0.999).