title: Ovarian activity and oestrous signs among group-housed, lactating sows: influence of behaviour, environment and production.
abstract: Animal welfare concerns require the development of housing systems that allow the animals to express their natural behaviour. One example of this is the group-housing system for lactating sows. The present study aimed at exploring ovarian activity in such a system. Thirty-eight sows farrowing individually outdoors during spring and summer, and indoors during autumn and winter, and group-housed in groups of four during weeks 3-7 of the lactation period, were monitored regarding reproductive functions, behaviour and production during their first to fourth lactation period. Average ovulation frequency during lactation was 47%. Only 50% of these ovulating cases were accompanied by a standing oestrus. Lactational ovulation frequency was higher in later parities (p < 0.001). Ovulation frequency was higher (p < 0.05) during winter (74%) and spring (69%), than during summer (10%) and autumn (23%). Occurrence of lactational ovulation was associated with some aspects of suckling behaviour and also with litter weight gain (p < 0.05). Forty-nine per cent of the lactational ovulations occurred during the seventh week of lactation. Timing of ovulation seemed positively (p = 0.08) associated with weight loss during lactation. Compared with the sows that were anoestrus during lactation, oestradiol-17beta values were higher (p < 0.05) only in the week before occurrence of lactational ovulation. Weaning-to-oestrous interval was prolonged (p < 0.05) among the sows that ovulated during lactation. The present study identifies several factors influencing ovarian activity among group-housed sows, thereby providing tools for the control of lactational ovulation in group-housing systems.
authors.affiliation: Department of Clinical Sciences, Division for Comparative Reproduction, Obstetrics and Udder Health, Swedish University of Agricultural Sciences, Uppsala, Sweden. fredrik.hulten@kv.slu.se
authors.forename: F
authors.initials: F
authors.lastname: Hultén
authors.forename: A
authors.initials: A
authors.lastname: Wallenbeck
authors.forename: L
authors.initials: L
authors.lastname: Rydhmer
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000827:Animal Welfare; D000818:Animals; D001522:Behavior, Animal; D001947:Breeding; D004777:Environment; D004971:Estrus; D005260:Female; D006799:Housing, Animal; D007774:Lactation / Q000502:physiology*; D008098:Litter Size; D010060:Ovulation / Q000502:physiology*; D010298:Parity / Q000502:physiology; D011247:Pregnancy; D012621:Seasons; D013552:Swine / Q000502:physiology*