Lactational oestrus in the sow 2. The influence of group-housing, boar presence and feeding level upon the occurrence of oestrus in lactating sows

Abstract

ABSTRACTA 2×2×2 factorial experiment investigated the effect on lactational oestrus in sows of housing system (group or singly housed; G v. S), boar presence (boar present or absent; B v. N) and feeding level (ad libitum or restricted; A v. R). All treatments were imposed from day 20 post partum until weaning at day 42. A total of 183 Camborough hybrid female pigs were used, providing between 21 and 24 animals within each cell in the experimental design.The occurrence of oestrus during lactation was observed as: 0·40 for G compared with 0·10 for S (P<0·01); 0·36 for B compared with 0·14 for N (P<0·05); and 0·28 for A compared with 0·21 for R (NS). The only treatment in which a high proportion of sows (0·78) showed oestrus was the combination G-B-A. Oestrus occurred during lactation on average 11 -4 days after imposing treatments, on average at day 20 post partum and 31·6 days after farrowing, and no significant differences were apparent between treatments. Individual piglet and overall litter weight gains were significantly reduced on G compared with S treatments (P < 0·01).Sow food intake was greater for the S compared with G, for N compared with B, and A compared with R treatments (P<0·001). Sows on the R treatment lost significantly more live weight than the A sows between days 20 and 42 (P<0·001). Singly-housed sows also lost more weight than group-housed sows between farrowing and day 42 (P<0·001), mainly because of losses occurring before day 20.