Sexual Activity of sows depending on birth quarter, sex and body weight at birth, and potential fertility
1999
Stasiak, A. | Walkiewicz, A. | Kamyk, P. | Wielbo, E. (Akademia Rolnicza, Lublin (Poland). Katedra Hodowli i Technologii Podukcji Trzody Chlewnej)
576 of Polish Landrace and 576 Polish Large White gilts were divided into groups according to: (1) season of birth (4 three-month periods); (2) litter sex ratio (30, 50 and 70 gilts); (3) birth weight (1000 g, 1000-1200 g and 1200 g). Sexual activity of gilts was observed from 150 days of age for 3 spontaneous oestrus cycles. Gilts were then divided into groups depending on the length of the 3rd oestrus (24, 36, 48, 60 and 72 h) which was determined by behaviour on exposure to a boar. Half the gilts were slaughtered after the third oestrus between the 5th and the 10th day of the next oestrus cycle; the number of corpora lutea was recorded and the genital organs were examined. The other gilts were mated and slaughtered between days 35 and 40 of pregnancy and the number of embryos was recorded. Gilts which showed a strong standing reflex had a greater number of corpora lutea or embryos than those which showed a weak standing reflex or did not react to the boar. Fertility was not affected by season of birth, sex ratio or birth weight
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