Effect of Sex Ratio in the Litter in Which Polish Large White and Polish Landrace Sows were Born on the Number of Piglets Born and Reared

Abstract

the aim of the study was to determine the effect of sex ratio in the litter in which Polish large white (Plw) and Polish landrace (Pl) sows were born on the number of piglets born and reared to 21 days of age. results obtained in nucleus herds from one breeding region were analysed. a total of 518 multiparous sows (179 Plw and 339 Pl) were evaluated based on data from their litters (790 Plw and 1540 Pl litters). the proportion of females in the litter in which the sow was born served as a basis for dividing the females into groups: group 1 <40%, group 2 -40-50%, group 3 -50-60%, group 4 -60-70%, group 5 >70%. significant differences in the average number of piglets born were found between the groups for Plw sows; compared to sows from groups 1, 2 and 3, females from group 5 gave birth to 8.0% (P≤0.05), 9.4% (P≤0.01) and 6.6% more piglets (P≤0.01), respectively, and compared to sows from group 2, those from group 4 gave birth to 5.1% more piglets (P≤0.05). The average number of piglets born and reared to 21 days by PL sows did not differ significantly between groups. the greater the proportion of females in the litter in which the Plw sow was born, the greater the preweaning mortality of piglets: 0.79, 0.87, 0.99, 1.02 and 1.24 piglets in groups 1 to 5, respectively. Preweaning mortality of Pl piglets (0.93, 0.89, 0.81, 0.76 and 0.65 in groups 1 to 5, respectively) decreased with increasing proportion of females in the litter of origin and was lower than that of Plw piglets. it seems appropriate to account for the sex ratio of the litter in which the gilts were born when selecting them as mothers of the next generation as part of herd replacement; this parameter may improve fertility and production efficiency.

The Effect of the Size of the Litter in Which the Sow Was Born on Her Lifetime Productivity

“…It was calculated that for a sow to produce at least seven piglets per 100 days of reproduction, gilts from litters of at least 12 piglets should be selected for breeding. This is supported by the results of Ptak [19] and Rekiel et al [24]. Kulisiewicz et al [7] underlined that late puberty (late coming into first estrus), late mating of a gilt, and the resulting late farrowing is a seriously adverse factor and indicates a high risk of early removal from the herd, which is consistent with our study.…”

Gilt Management for Fertility and Longevity

“…The sex ratio of the litter where the replacement female was born may affect lifetime performance and behavior and could potentially be used as another selection tool at birth [34,35]. Gilts born to litters with a high proportion of males are exposed to increased levels of androgens from their male littermates in utero causing gilts to become masculinized [34,36].…”

“…Conversely, Drickamer et al [38] reported that females from litters with a male-biased sex ratio attained puberty later. Nevertheless, further studies reported that gilts from male-biased litters were more likely to have lower successful inseminations, higher insemination failures, lower mating success, fewer pigs born, and less teats as compared with gilts from female-biased litters [35,36,38,39]. Masculinized females from male-biased litters are also more likely to display male-like behaviors, are less likely to be fearful, and more likely to be aggressive than gilts from female-biased litters [40].…”

Differences in piglets sex proportion in litter and in body weight at birth and weaning and fattening results

“…Females born from March to August farrowed more gilts in their litters (Górecki, 2003). Rekiel, et al (2011) and Walkiewicz, et al (2000) have demonstrated that gilts which are from the litter with a greater female sex proportion than 50%, received better results in reproduction. Bocian, et al (2010a) have demonstrated that more gilts was born in litters of primiparous than multiparous sows.…”