Reproduction performances and conditions of group-housed non ...

- Paper IV -
mixed model using the glmmPQL function in the MASS package (Venables & Ripley,
2002) of R (R Development Core Team, 2004).
3. Results
For the reproduction parameters, the overall averages and the variation between sows
across all 14 herds are presented in Table 1. In average, the sows involved in this study
showed a very high litter size of nearly 15 born piglets per litter. The percent of re-mated
sows varied from 0 to 45% and the number of born piglets per litter varied from 13.6 to
15.7 between the herds.
Table 1. Overall level and variation in different production parameters for all focal sows
N Mean Std Min Max
Interval from weaning to first mating, days 541 5.3 - 2 40
Re-mated sows, % 541 11 - - -
Culled in all, % of weaned 554 4.4 1) - - -
Total number of born piglets/litter 2) 437 14.8 3.3 4.0 24.0
Number of dead born/litter 437 1.5 - 0 12
1) Any sows culled after re-mating are not included 2) Alive and dead born
Parameter estimates and standard errors from the analysis of weaning to first mating interval,
pregnancy chance and litter size are shown in Table 2. There were no effects of % not
eating, aggressions after mixing, fear or lying behavior for any of the dependent variables.
Weaning to first mating interval. The total number of skin lesions at mating tended to correlate
positive with weaning to first mating interval (P=0.07) and a significant two-factor interaction
between back fat at weaning and parity was found, in that the interval decreased
with increased back fat at weaning but only for first parity sows (Figure 1). Further, a significant
negative correlation with lactation length was found. No main effects or interactions
with parity for aggressions, fear category or lying behaviour were found.
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