Analysis of the reproductive qualities of crossbred sows and determining the effect of a combination at crossing

It is presented the comparative analysis of a manifestation of reproductive qualities of purebred and two-breed sows in combination with boars of different genotypes and the definition of the best forms for further receiving highly productive marketable young pigs. The researches were conducted in the conditions of SE EE "im. Dekabrystiv "of Institute of Pig Breeding and AIP NAAS of Myrhorod district of Poltava region. 5 groups of young animals were formed for the experiment: 1 – (LW×Landrace)×Landrace, 2 – (LW×Landrace) x Duroc, 3 – LW×Duroc, 4 – Landrace×Landrace, 5 – Myrhorod breed x Myrhorod breed. It was determined the fact that by index of the number of piglets born, sows of the combination (LW×L)×D were dominated the purebred Landrace females by 7.41 % (p≤0.05) and pigs of Myrhorod breed by 9.59 % (p≤0.001). The significant variability of the rich fertility index in the sows of the combination of LW×L was revealed: the standard deviation in them was 3.56 heads (compared to 1.22 in other groups), the indicators of the magnitude of variation and the coefficient of variability were also the largest (respectively 10 heads and 10.71 %), which is confirmed by the value of the coefficient of excess – 2.689. The crossbred sows with the LW×L combination had the highest litter weight, they exceeded the sows of Myrhorod breed by 44.2 % (p <0.001) and tended to exceed the sows of Landrace breed by 3.51 %. It should be noted that the weight of the litter at weaning in Landrace sows was 68.3 kg, with a positive asymmetry – 0.743 and an excess coefficient of 0.467; the coefficient of variation was low, which indicates targeted selection for growth intensity in pigs of this breed. According to the results of the researches, the level of combination and the effect of crossing genotypes by multiplicity and the litter weight at weaning were determined. The level of combination of genotypes by crossing exceeded the level of combination by purebred breeding and had positive values in terms of fertility. The highest value of this indexes was obtained from the combination of crossbred sows with boars of Duroc breed – +0.70 units.The next stage of researches was to determine the effect of heterosis. The efficiency of combination (LW×L)×D was determined – 106.93 points for the multiplicity. According to the index of litter weight at weaning, the effect of heterosis was found out at crossing and in pigs of Landrace breed (for purebred breeding). Its highest value was determined in the combination of LW×L – 111.34 %, which indicates the effective use of this combination in the first stage of hybridization. The use of industrial crossbreeding and hybridization in the herd of SE "EE im. Dekabrystiv” helps to increase the multiplicity rate of sows, as well as proves the effectiveness of the use of crossbred sows of the combination LW×L in the first stage of the hybridization to increase the growth rate of young animals. Indexes of the level of combination and the effect of heterosis should be used to assess the effectiveness of crossbreeding in pig breeding. Key words:sows, multiplicity, litter weight, crossbreeding, heterosis, hybridization, genotype.