Influence of various hormones and hormonic preparations on the reproductive performance of sows

Abstract

This article surveys research on regulation of reproductive cycles in sows in Lithuania, carried out during the period of 1980-1985, the time of intensive industrialized swine production. This experimentation was the first approach to study the effects of estrus and ovulation stimulation with substances, such as suisynchron, Evertas-P. The possibilities to use progesterone and megestrole acetate of pirogliutaminic acid, PMGS, chorionic gonadotropin to improve reproductive characteristics of sows are also discussed. INTRODUCTION Organizing industrialized production of pork and introducing new technologies, much attention now is being paid to regulation of sexual cycle. Group farrowing under various conditions of pig housing have been practiced for many years. It is easier to achieve the goal with primiparous sows, because of synchronized estrus in about 3- 4 days after weaning. It is more complicated to provoke synchronization oestrus in gilts and quite impossible to achieve this by changing conditions of housing. Intensifying swine-breeding and introducing inseminations efficiency and profitable production have been obtained by simple but effective means of synchronization. This investigation of estrus synchronization is aiming at two practical problems: 1. To regulate time of ovulation so that sampling and insemination could be done on foreseen terms. 2. To achieve high conception rates in swine considerable results in regulating estrus and ovulation by pharmacological substances have been achieved during the last two decades. According to the present investigation four methods to synchronize estrus can by pointed out: 2.1. The induction of ovulation. It is the best means to provoke ovulation in group of pigs on exact time. However of the method depends on the phase of a sexual cycle, where preparation ought to be used. E.g. an injection of PMGS given only once at the follicular phase of sexual cycle stimulat[...].