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This experiment was performed on a 6,000 sow, commercial farrow-to wean facility during the summer months. At onset of estrus, sows were randomly assigned to one of four treatment groups: 1) sows maintained in stalls from weaning through the remainder of gestation (Stall, n=20/replicate);
2) sows housed in stalls after weaning and then mixed in groups of 58 immediately after breeding (D 3 Mix); 3) sows housed in stalls after weaning and mixed in groups of 58 at day 14 of gestation (D 14 Mix), and 4) sows housed in stalls from weaning until after d 35 of gestation and then mixed in groups of 58 (D 35-Mix).
According to preliminary reproductive results, there was an effect of treatment on both conception
rate and farrowing rate. Conception rates for sows in both the D3 and D 14 Mix were lower than sows kept in Stalls and those in the D 35 Mix groups. Sows in the D 35 Mix did not have a significantly lower conception rate than those in Stalls. Farrowing rates were also lower in the D 3 and D 14 Mix treatments compared to those kept in Stalls. However, only the D 3 Mix group was lower than the D 35 Mix and sows assigned to D 14 Mix were not significantly lower. Again, sows in the D 35 Mix did not differ in farrowing rate compared to Stalls. There was no effect of treatment on the averages for total born pigs, pigs born alive, stillborn, or mummified fetuses.
The results from this study lead us to conclude that mixing sows early at D 3-7 after breeding and during the implantation period (D13-17) can be associated with a 5-7% reduction in conception rate when compared to sows housed in Stalls or those mixed after day 35 of gestation. Farrowing rates were also reduced as a result of mixing sows immediately after breeding on Day 3 and at the time of implantation on Day 14 when compared to sows housed in Stalls. Further, mixing at Day 3 was also detrimental to farrowing when compared to mixing sows after day 35 of gestation. Surprisingly, mixing sows at the time of implantation on D 14 did not reduce fertility when compared to sows that were mixed after d 35 of gestation. For reproductive measures alone, these results suggest that mixing sows in the 1st or 2nd week of gestation can result in reduced conception and farrowing rates when compared to housing sows in stalls. However, as expected, mixing sows after day 35 in gestation did not reduce conception or farrowing rates compared to sows housed in stalls.
M. Hopgood; L. Greiner; J. Connor; J. Salak-Johnson; R. Knox. Effect of day of mixing gestating sows on reproductive fertility and animal well-being. 2011 Allen D. Leman Swine Conference.
