Effects of group-size-floor space allowance during the nursery phase of production on growth, physiology, and hematology in replacement gilts
S. R. Callahan, A. J. Cross, A. E. DeDecker, M. D. Lindemann and M. J. Estienne
The objective was to determine effects of nursery group-size-floor space allowance on growth, physiology, and hematology of replacement gilts. A 3 × 3 factorial arrangement of treatments was used where in gilts classified as large, medium, or small (n = 2537; BW = 5.6 ± 0.6kg) from 13 groups of weaned pigs were placed in pens of 14, 11, or 8 pigs resulting in floor space allowances of 0.15, 0.19, or 0.27 m2/pig, respectively. Pigs were weighed on d 0 (weaning) and d 46 (exit from nursery). The ADG was affected by group-size-floor space allowance × pig size (P = 0.04). Large-and medium-size gilts allowed the most floor space had greater (P <0.05) ADG than similar size gilts allowed the least floor space but for smallsize gilts there was no effect (P > 0.05) of group size-floor space allowance. Mortality in the nursery was not affected (P > 0.05) by treatment, size, or treatment × size and overall was approximately 2.1%. Complete blood counts and blood chemistry analyses were performed on samples collected at d 6 and 43 from a subsample of gilts (n = 18/group-size-floor space allowance) within a single group. The concentration (P < 0.01) and percentage (P = 0.03) of reticulocytes was the least and red blood cell distribution width the greatest (P < 0.01) in gilts allowed 0.15 m2 floor space (effects of treatment). Blood calcium was affected by treatment (P =0.02) and concentrations for gilts allowed the greatest and intermediate amounts of floor space were greater (P < 0.05) than for gilts allowed the least floor space. Serum concentrations of cortisol were not affected by treatment × day (P = 0.27). Cortisol concentrations increased from d 6 to d 43 in all groups and were affected by day (P < 0.01) but not treatment (P =0.53). Greater space allowance achieved by placing fewer pigs per pen in the nursery affected blood parameters and resulted in large- and medium-size replacement gilts displaying increased ADG. Further study will determine if these effects influence lifetime reproductive capacity and sow longevity.