Sow and Litter Performance for Individual Crate and Group Hoop Barn Gestation Housing Systems: Progress Report III

Iowa State University Animal Industry Report 2006. The effects of gestation system on sow and litter performance over a 2.5 year period were evaluated at the Iowa State University Lauren Christian Swine Research and Demonstration Farm near Atlantic, IA. Gestation housing system treatments were 1) individual gestation crates in a mechanically ventilated, partially slatted floor manure flush confinement building (C); and 2) group pens with individual feed stalls in deep-bedded, naturally ventilated hoop barns (H). Sows were artificially inseminated in a mechanically ventilated, partially slatted floor confinement breeding barn. Sows were moved as a group to their assigned gestation housing treatment by the ninth day post-weaning. Sows were randomly assigned to gestation housing treatment when the project commenced. All first parity gilts were gestated in individual crates and randomly assigned to a gestation group after breeding for the second parity. Farrowing occurred throughout the year on a bi-weekly schedule. All sows received 2.04 kg per day of a corn-soybean meal diet. During the last trimester of gestation, feed allowance was increased to 2.72 kg. During the winter H sows were fed 25% more feed and C sows were fed 5% more feed. Reproductive performance was summarized for 957 litters and analyzed using general linear models. Number born alive per litter was different for the two housing treatments (P<0.001) with H resulting in 0.8 more pigs born per litter. Parity differences were also noted (P<0.01), however there was no interaction between parity and treatment (P>0.1). H sows also weaned 0.4 pigs more per litter (P<0.01). Pre-wean mortality rates did not differ (P=0.58) between the two gestation housing treatments. Cross fostering occurred to approximately equalize litter size within a farrowing room. The effects of parity, farrowing season (quarterly), pig birth weight, and lactation length on pre-wean mortality were significant (P<0.01). There was a trend for C sows to have a 1-day shorter wean-to-conception interval (P=0.07). Farrowing rates for the two treatments were not different (P=.66). There was an interaction (P<0.1) between breeding season (quarterly) and treatment with H sows bred in summer and C sows bred in autumn having the lowest farrowing rate. There was no correlation between treatment and reason for culling (P>0.1). Failure to conceive was the leading reason for culling in both treatments. There was a trend for sows gestated in C to be culled for feet and leg unsoundness. H sows tended to be culled for poor body condition. Results indicate that gestating sows can be housed in deep-bedded hoop barns equipped with individual feeding stalls and achieve results comparable or superior to gestating sows housed in individual crated gestation systems.