THE PHENOMENON OF SEXUAL DIMORPHISM IN THE CONTEXT OF REARING PIGS OF MODERN COMMERCIAL BREEDS UNDER CONDITIONS OF THE SOUTH OF UKRAINE

Ruslan Susol, Katerina Garmatyuk, Oleksandr Tatsiy

Abstract
    Our research aimed to study the effect of sexual dimorphism as a biological phenomenon on growth rates of young stock of different origin under conditions of breeding and commercial herds at the current stage of pig production development in the South of Ukraine. Sexual dimorphism (fm) in pigs of different genetic origin is defined as a ratio of the male to female body weight at a certain age, expressed as a percentage, with fm > 100% for a population with normal sexual dimorphism in body weight and fm <100% for a population with reverse sexual body weight dimorphism. The following has been observed in young pigs of different origin during early ontogenic stages: boars tend to be heavier than gilts at birth, and such a pattern is maintained during the suckling period; however, this difference is levelled by 60 days of age; it results in trend changes in favour of gilts that outpace boars in terms of body weight at 90 and 120 days of age, which is indicative of their better adaptation to weaning. The difference between sexes at 150 days of age is levelled again, but by 180 days of age there is already a clear trend for greater body weight observed in boars as compared to gilts. Once representatives of the Large White and Pietrain breeds of both sexes reach a year or two years of age amid common pattern of normal sexual dimorphism in body weight, such outperforming of males over females is slightly more prominent for Large White animals as opposed to Pietrain pigs.