Ovulation frequency among sows group-housed during late lactation

A review of sow and piglet behaviour and performance in group housing systems for lactating sows

“…Lactational ovulations were also associated with higher piglet weight gains between grouping and weaning at 7 weeks of age (Hultén et al, 2006), but this might also be a consequence of high piglet feed intake as piglets had access to sow feed from 2 weeks of age onwards. Sow weight loss, backfat thickness and litter size did not differ between sows with and without lactational ovulation (Hultén et al, 1995a and. In addition, group size was unrelated to the occurrence of lactational ovulation (Hultén et al, 1995a).…”

“…Sow weight loss, backfat thickness and litter size did not differ between sows with and without lactational ovulation (Hultén et al, 1995a and. In addition, group size was unrelated to the occurrence of lactational ovulation (Hultén et al, 1995a). Weary et al (2002) reported no lactational oestrus in a GA system.…”

“…At weaning between 5 and 6 weeks p.p., Hultén et al (1995a and1995b) reported complete udder atrophy in, respectively, 5.0% and 6.6% of the multiparous sows, whereas Hultén et al (2006) did not note termination of milk production before weaning at 7 weeks of age. Udder atrophy before weaning never occurred in individual housing and in first-parity MS-housed sows (Hultén et al, 1995a and1995b). Bohnenkamp et al (2013a), however, reported that primiparous sows were more disturbed around nursing and reduced their nursing frequency sooner than multiparous sows did.…”

“…In MS housing, however, more competition at the udder occurs, which may result in higher levels of udder and teat damage. Sow health has not been investigated in the reviewed studies with GA systems; however, on MS farms, indeed fewer sows were culled because of locomotory problems (Hultén et al, 1998) and fewer sows suffered from scapular abscesses (3.0% v. 13.4% of sows), hoof abnormalities (4.6% v. 9.1% of sows), and teat wounds and udder lesions than on farms with individually housed sows (Hultén et al, 1995b). However, this may also be related to the higher amount of straw bedding that was available.…”

“…Lactational ovulation can, however, be induced when suckling intensity is substantially reduced or by stress (reviewed by Langendijk et al, 2006). In MS housing, the occurrence of lactational ovulation ranged from 0% to 100% (Bryant et al, 1983;Hultén et al, 1995a;Wechsler, 1996;Wattanakul et al, 1997;Hultén et al, 2006;Kongsted and Hermansen, 2009) and was associated with a shorter nursing duration per nursing bout at 4 weeks p.p. and a lower number of piglets present at nursing between weeks 4 and 6 p.p.…”