Lactational oestrus in the sow 4. Variation in the incidence and timing of lactational oestrus in groups of sows

Abstract

Eighty multiparous Camborough hybrid female pigs (sows) and their litters, on average 15 days post partum, were housed in groups of five in multi-accommodation pens. The sows were fed ad libitum on a proprietary diet containing 160 g crude protein per kg from grouping to 30 days post partum, when they were fed to scale twice daily in individual feeders until weaning at 42 days post partum. One of four Large White male pigs (boars) was introduced to each group on the day following grouping, each boar being run with four groups.Oestrus occurred in 62 sows, on average 10-2 ± 3-3 days after grouping. The differences between groups in the interval from grouping and boar introduction to the onset of oestrus were statistically significant (P < 0-01). Neither the incidence nor the timing of oestrus could be related to the identity of the boar.Regression analysis revealed relationships between a number of independent variables and the incidence and timing of lactational oestrus. Sows which gained more live weight from farrowing to weaning and whose litters consumed more creep food were more likely to show lactational oestrus. Sows were slower to show lactational oestrus when they gained little weight from farrowing to weaning, had lower live weights at weaning and gained less weight from the previous weaning, despite eating comparatively more food during grouping. The sows which took longer to show lactational oestrus also had heavier piglets at grouping and more piglets in their litters at weaning. The difficulties arising in the interpretation of these results are discussed.

Ovarian Activity and Oestrous Signs among Group‐Housed, Lactating Sows: Influence of Behaviour, Environment and Production

“…High frequency of lactational oestrus has been associated with boar contact, a high feeding level, maintained or increased body weight and backfat, and small litter size (Petchey and Jolly 1979; Rowlinson and Bryant 1982; Bryant et al. 1983), but the results from the present study and those of Hultén et al.…”

Influence of Duration of Litter Separation and Boar Exposure on Estrous Expression of Sows during and after Lactation

“…Grouping sows and their piglets at 2 to 3 wk postpartum in the presence (Petchey and Jolly, 1979;Bryant, 1981, 1982;Duggan et al, 1982), or absence (Smith, 1961) of a boar resulted in estrus and(or) fertile rnatings during lactation. In some studies, sows grouped with their litters, but not exposed to boars (Bryant et al, 1983), exhibited estrus less frequently than sows grouped together, exposed to boars, and fed ad libitum (Rowlinson and Bryant, 1976;Petchey et al, 1978;Bryant and Rowlinson, 1984). Sow and litter separation (6 or 12 h/d) induced estrus during lactation when boar exposure was provided (Walker and England, 1977;Stevenson and Davis, 1~984).…”

A 25 years experience of group-housed sows–reproduction in animal welfare-friendly systems

“…Various types of group housing for lactating sows have been developed and scientifically evaluated during the last 50 years [ 27 ] and it has become evident that onset of oestrus is highly variable in group-housing conditions. Experimental and observational studies have shown that apart from a decrease in suckling intensity in these systems [ 28 ], several other factors such as boar contact and feeding intensity are correlated to return to oestrus during lactation [ 29 , 30 ]. The idea of stimulating the sows to return to oestrus and be mated during lactation, as a means of improving production output, was, however, soon abandoned as the disadvantages connected to this became evident.…”