18 Does crowding in the nursery affect future sow reproductive performance and longevity in the breeding herd?

摘要

We previously reported that crowding in the nursery decreased growth rate and affected blood chemistry and hematology measures in gilts. In the current experiment, weanling gilts were allowed decreased floor space in the nursery to determine effects of crowding on their future litter sizes and retention as sows. Of 2,537 gilts classified at weaning as large (6.92 kg), medium (4.42 kg), or small (5.60 kg) and reared in nursery pens of 14, 11, or 8 pigs (to allow 0.15, 0.19, or 0.27 m2 floor space/pig, respectively), 1,453 gilts were selected for breeding and distributed among 11 sow farms. As expected, total litter size (12.94, 13.28, and 13.99; SE = 0.13) and born alive (12.21, 12.64, and 13.23; SE = 0.11) increased (P < 0.01) from parity one to three. A tendency (P = 0.08) existed for a quadratic relationship between space and total litter size [13.39, 13.54, and 13.27 (SE = 0.13) for gilts allowed 0.15, 0.19, or 0.27 m2 floor space/pig, respectively]. A linear effect of pig size (P = 0.03) on stillborns was detected (0.64, 0.75, and 0.75, for small, medium, and large, respectively). There was no effect of space on the percentages of gilts completing zero (P = 0.36), one (P = 0.35), two (P = 0.32) or three (P = 0.50) parities. However, the percentage of small gilts completing zero parities was greater (P < 0.01), and the percentage completing one parity was less (P < 0.01) than for large or medium gilts. Abortion rate was greater (P < 0.01) in gilts classified as small (2.51%) or medium (1.36%) compared with large (0.20%). Floor space allowed in the nursery did not remarkably affect litter sizes or retention through three parities in sows. Compared with larger pigs, however, more small pigs entering the breeding herd did not complete a parity and displayed a greater abortion rate.