The article highlights the optimal variant of main herd sows artificial insemination multiplicity definition.

The research was carried out at the “Shubske” Farm of Bogodukhiv District of the Kharkov Region at the pig farm of Welsh breed pure breeding. The 120 sows totally (by 12 per week with an even distribution in groups with different insemination multiplicity) was selected for the optimal multiplicity (from one to four times) estimation. The following indices of sows reproductive capacity: number of born alive, weight of the nest at birth and weaning and piglets survival before weaning on the 28th day were evaluated per the sows groups. Recalculation to the nest mass at the weaning at 45 days was carried out according in the current instruction of pigs appraisal.

The research results were estimated by traditional methods of variation statistics. The Microsoft Excel was used for database creation and data statistical analysis.

In the conditions of small and medium-size farm the boars-sires using efficiency is small. Usually, the number of boar-sire exceeds the required load in order to the risks reduce. Accordingly, there is a significant reserve for the a larger number of sperm-dosages using per sow. At the same time, the duration of the period of sows productive insemination during estrus (up to 36 hours after estrus detection) allows to increase the multiplicity of insemination to four or more times.

In the first place, the percentage of productive fertilized sows was estimated for each group with different multiplicity of their insemination during estrus. As a result, different efficacy of sows was detected. The sows were used most effectively for their three-time and quadruple insemination (93.33 % for both variants). For double insemination, the indicator was slightly less effective – 90.00 %. The smallest percentage of productively-fertilized sows was obtained for single insemination – 86.67 %. At the same time, the difference in the most contrasting groups for this indicator was 6.66 %. Between the groups within the limits of the double-quadruple insemination the difference was two times smaller – 3,33 %.

The main effective reproductive capacity indicator of sows is themultiplicity. The maximum values of sows multiplicity were obtained at quadruple and triple insemination (p <0.01 to the once insemination sows group). The predominance of other groups of sows for quadruple insemination was in the range of 0.23–12.42 %. The greatest difference was obtained between the groups for single and four-time sows insemination. At the same time, the difference between the triple and quadruple insemination was insignificant (0.03 piglets per sows per farrow in absolute terms). The difference between double insemination compared to triple and quadruple was significantly higher (0.08 and 0.11 piglets per sows per farrow in absolute terms). There were no differences between the groups of the sows for the double, triple and quadruple insemination. There was a sequence – 1.5 piglets, 0.08 piglets, 0.03 piglets at the multiplicity difference compare to the insemination frequency increasing. Accordingly, the greatest effect to the multiplicity was occurred at the multiplicity of insemination increasing from single to double.

The sows multiplicity growing also positively affected to the average weight of the nest at birth. At the same time, the average weight of one piglet at birth with an increase of multiplicity did not increase.

The largest values of weight of the nest at birth were obtained triple and quadruple sows insemination (p <0.01 to the once insemination sows group). At the same time, the difference between groups of double and single insemination by this indicator was unreliable. There was a sequence – 0.5 kg, 0.75 kg, 0.03 kg at the difference in weight of the nest at birth compare with a frequency of insemination increasing. Consequently, the greatest effect to the weight of the nest at birth was occurred at multiplicity of insemination increasing from double to triple.

No less important sows reproductive ability indicator is the weight of the nest at weaning. Though at most farms the early weaning of piglets from sows is used, the recount on the 45th or 60th day after weaning is used for the comparative assessment.

The largest values of weight of the nest at weaning were also obtained for quadruple and triple insemination. However, there was no significant difference in the weight of the nest at weaning in the groups of the sows with different rates of insemination. Compared to a group of sows at single insemination the double - quadruple insemination allows to obtained additionalat 1.13–1.67 % larger nest at weaning (the difference between the groups is unreliable).

In addition, the piglet survival at weaning was estimated. The obtained results indicate a decrease of the survival index with multiplicity growing.

The smallest piglets survival before weaning was obtained for the group with quadruple insemination, the greatest piglets survival – with single insemination.

The sows multiplicity insemination increasing during estrus from single to double is increases the efficiency of sows using by 3.33 %, to triple and quadruple – by 6.66 %.

The effectiveness of double – quadruple sows insemination of the main herd was established compared to single insemination. For such variants of insemination, the maximum values of sows multiplicity – 12,96 and 12,93 piglets per farrow (p <0.01 to the once insemination sows group) were obtained.

The multiplicity increasing was positively affected to weight of nest at birth and at weaning increasing.

Prospects for further researches are the complex reproductive ability assessment at the expense of breeding and evaluation index, different multiplicity of checked sows insemination estimation.

Key words: pig breeding, productivity, reproductive ability, artificial insemination, sows, multiplicity of insemination, sperm of boar-sire.