Reproductive Performance Among Sows Group-Housed During Late Lactation

Abstract

Four farms (540 sows) that group-housed sows from 2 weeks of lactation until weaning (G-farms) and 3 farms (300 sows) — used as controls — that kept the sows individually penned throughout the 5- to 6-week-long lactation period (C-farms) were compared in terms of reproductive performance. All sows were crossbred Swedish Yorkshirex Swedish Landrace. Sows were kept in groups in the breeding section and were also grouped on deep litter in the dry-sow section on all farms. Batchwise farrowing routines were used on all farms, and batch size ranged between 8 and 22 sows. Fertility and culling data were collected in connection with monthly visits to the farms for 16 months. Among the older (≥ 5th parity) sows, litter sizes were significantly (p = 0.02) smaller in the G-farm group compared with the C-farm group. The percentage of sows mated within 10 days post weaning was lower (p<0.001) in the G-farm group than in the C-farm group, with the difference being most evident among the older (≥ 5th parity) sows. The frequency of repeat breeders among primiparous sows was similar in the 2 housing systems, but among the multiparous sows repeat-breeder frequency was higher (p = 0.04) in the G-farm group than in the C-farm group. In both groups, repeat-breeder frequency seemed to be highest from July to September. Repeat breeding/failure to farrow was a common reason for culling in the G-farm group. These results indicate that reproductive performance was impaired in the group-housing system. This impairment could have been due partly to the occurrence of lactational oestrus, which makes it difficult to maintain adequate routines for oestrous detection and mating/insemination.

Sammanfattning

Reproduktionsresultatet utvärderades i fyra besättningar som grupperade suggorna från två veckor efter grisningen till avvänjningen (G-gruppen) samt i tre besättningar (kontroller) som inhyste suggorna enskilt under hela diperioden (K-gruppen). Samtliga suggor var svensk yorkshirexsvensk lantras och diperioden var 5–6 veckor lång. Suggorna grupperades i betäcknings- och i dräktighetsavdelningen. I samtliga besättningar grisade suggorna omgångsvis och varje omgång bestod av 8–22 suggor. Under 16 månader insamlades reproduktionsdata genom regelbundna gårdsbesök.

Bland de äldre (≥ 5 grisningar) suggorna var kullstorleken signifikant (p = 0.02) mindre i G-gruppen än i K-gruppen, medan det ej förelåg någon skillnad bland de yngre suggorna. Andelen suggor som betäcktes inom 10 dagar efter awänjningen var lägre (p<0.001) i G-gruppen än i K-gruppen. Denna skillnad var mest påtaglig bland de äldre suggorna. Bland förstagrisarna var omlöpningsfrekvensen ungefär lika i båda inhysningssystemen, medan en signifikant (p = 0.04) större andel av de äldre suggorna i G-gruppen löpte om jämfört med de äldre suggorna i K-gruppen. I båda grupperna verkade omlöpningsfrekvensen vara högst under perioden Juli-September. Omlöpning/utebliven grisning var en vanlig slaktorsak i G-gruppen. Resultaten indikerar att reproduktionsresultatet är sämre i gruppsystemet. Orsaken kan delvis vara förekomst av brunst under diperioden vilket försämrar möjligheterna att upprätthålla optimala betäcknings/inseminationsrutiner.