title: Factors associated with prolonged weaning-to-mating interval among sows on farms that wean pigs early.
abstract: OBJECTIVE
  To determine factors associated with weaning-to-mating interval among sows on commercial farms that wean pigs early.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  11,861 farrowing sows.
  
  
  METHODS
  Production, farrowing, and feed intake records were reviewed for sows on 16 farms for which mean duration of lactation was between 14.9 and 18.9 days.
  
  
  RESULTS
  Among sows with high feed intake during lactation (> or = 5.6 kg/d [12.3 lb/d]), lactation duration was not associated with weaning-to-mating interval, but among sows with low feed intake during lactation (< 5.6 kg/d), weaning-to-mating interval increased as lactation duration decreased. Furthermore, among sows with the lowest feed intake during lactation (< 4.2 kg/d [9.2 lb/d]), those that had heavier litter weights at weaning (> 54 kg [119 lb]) had a longer weaning-to-mating interval than did those that had lighter litter weights at weaning. Sows with low feed intake and high litter weight at weaning accounted for 5 to 20% of sows on each farm. In general, weaning-to-mating interval increased as parity decreased, but the change in weaning-to-mating interval associated with a particular change in lactation duration varied with parity.
  
  
  CONCLUSIONS
  When feed intake during lactation is maximized (> or = 5.6 kg/d), lactation duration is not significantly associated with weaning-to-mating interval. Producers should consider fostering or partially weaning litters when sows with high litter weights are not consuming sufficient feed.
authors.affiliation: Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St Paul 55108, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Koketsu
authors.forename: G D
authors.initials: GD
authors.lastname: Dial
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001947:Breeding; D015331:Cohort Studies; D004435:Eating / Q000502:physiology*; D005260:Female; D007774:Lactation / Q000502:physiology*; D008098:Litter Size; D010298:Parity; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D013552:Swine / Q000502:physiology*; D013997:Time Factors; D014886:Weaning