One of the most important technological methods to increase the efficiency of livestock production is to ensure the maximum duration of the economic use of animals. Prolonged use of farm animals is one of the main indicators of high culture of management. Duration of economic use of farm animals depends on many factors. The issue of determining the optimal duration of the economic use of pigs has not lost its topicality today.

Intensive exploitation of pigs in a year-round confinement indoors turned out to be effective because of the acquisition of farm animals with constitutionally strong and with high natural resistance animals which have genetically stable indicators. And this, in its turn, has led to the need to use more intensive traditional and new more effective methods of breeding ensuring high productivity of the animals for a long time.

The purpose and task of research were to analyze and study the features of the age dynamics of indicators of reproductive qualities of two-breed sows and to identify more productive parent form.

For the research the indicators of reproductive performance of two-breed sows combinations were used: Ukrainian Meat (UM) × Landrace (L) and Large White (LW) × Landrace. The research was conducted in a Limited liability company (LLC) "Tavriyskiye svinii" in Skadovsk, Kherson oblast. The evaluation of reproductive qualities was held according to the results of seven consecutive litters.

Reproductive performance of sows was evaluated on the following criteria: total number of piglets at birth, multiple pregnancy, the percentage of stillborn piglets, number of piglets at weaning, weaning weight of the nest, the average weight of one pig at weaning. Studies were carried out according to generally accepted zootechnical methods.

As a result of our research it was found that the rate of the total number of piglets at birth in the context of two combinations of sows UM × L and LW × L was the largest in fourth and fifth farrowing respectively.

Multiple pregnancy rate is characteristic, it should be mentioned that the combination of sows (UM × L) and (LW × L) was the lowest value in the first farrowing (9.32; 9.58), and the largest on the results of the fourth farrowing – 11.62; 11.04 animals respectively.

It should be also mentioned that the combination of sows (UM × L) during the fifth and sixth farrowing had a fairly high rate of multiple pregnancy and slightly inferior to the peak value at the fourth farrowing compared with sows (LW × L), which sharply reduced the value of multiple pregnancy.

If we consider the dynamics of changes in the values of attributes that characterize the reproductive performance of two-breed sows of both combinations, we can define the following trends: the total number of indicators piglets at birth, multiple pregnancy, number of piglets at weaning at 30 days of age tend to increase from the first to the sixth farrowing, with minor fluctuations, but in older animals (seventh farrowing) values of these attributes is sharply reduced.

The results also show a significant increase in the proportion of stillborn piglets in nests with increasing age sows. Especially significant increase is observed after the fourth farrowing sows combination (LW × L), and a combination of sows (UM × L) increase in this indicator was observed after the fifth farrowing.

We found an increase in the number of stillborn fetuses with increasing age of the sows which is consistent with literature data. One of the main reasons for this trend is the perinatal asphyxiation, which is caused by prolongation of the duration of the birth process, due to age-related decrease in muscle tone of the uterus.

Along with anatomical and physiological factors, one of the main reasons for the high stillbirth may also be incomplete or poor performance of technology and veterinary activities during farrowing.

Evaluation of preservation of suckling piglets almost show no age dynamics and varied almost at the same level for animals of different ages and different breed combinations. Age dynamics of the mass of one pig at weaning, as well as the mass of the entire nest at weaning, has a variable trend in the context of number of farrowing sows and breeds of sows.

Since of its first peak data rates achieved in sows, both combinations in the third farrowing, but then again falling on the fourth farrowing and in older animals (fifth and seventh farrowing) reach the second maximum weight at weaning piglet.

Thus, high levels of reproductive qualities of sows of both combinations are inherent in the animal until the fourth or fifth farrowing. In the future, the total number of piglets at birth remains almost constant, but an increasing proportion of stillborn piglets thereby causes decrease in multiple pregnancy. Furthermore, after the fourth farrowing it was noted preservation fluctuation in piglets suckling period for both mass and one piglet nests and generally at weaning. Obviously, this is related to dairy of sows.

High rates of reproductive qualities of sows of both combinations are inherent in animals until the fourth or fifth farrowing, so it is nessesary to have the highest number of sows of this age in the herd.

Comparing reproductive performance of sows of two combinations, it should be mentioned the superiority of sows (UM × L) on the basic parameters, as well as maintaining the highest rates in the later age periods.

Key words: sow, interbreeding, reproductive performance, age dynamics, Large White breed, Ukrainian meat breed, Landrace breed.