Effect of weaning age on nursery pig and subsequent sow reproductive performance
The objectives of this study were to: (1) quantify the effect of piglet birth weight on weaning and nursery off-test weights, (2) assess the effect of weaning age on nursery pig performance, and (3) model the effect of weaning age on subsequent sow reproductive performance. The study utilized Danbred N.A. (Columbus, NE) barrows and gilts (n=2,467) from a commercial maternal line multiplication herd. Litters were randomly assigned at birth to either a 15 d (pigs weaned at 14, 15, and 16 d of age) or a 20 d (pigs weaned at 19, 20, and 21 d of age) average weaning age group. Increasing birth weight from 0.94 to 2.06 kg improved subsequent growth performance. Collectively, birth weight and weaning weight are important predictors of subsequent nursery growth performance. The research also defined how weaning age affects ADG, ADFI, mortality %, G:F, and feed cost/kg gain in the nursery phase of production. Pigs weaned at 20 d had greater ADG, increased ADFI, fewer pigs removed from the test, similar G:F ratios, and lower feed cost/kg gain when compared to pigs weaned at 15 d. Pigs in the 20 d weaning age group were also heavier at the end of the 42 d nursery phase of production when compared to pigs weaned in the 15 d group. Based on the differences seen in pigs weaned at 20 d and 15 d, weaning pigs at 20 d may prove advantageous in commercial operations because of the improvements in nursery growth performance. The research also analyzed the effect of lactation length on wean-to-estrus interval (WSI), wean-to-conception interval (WCI), and subsequent litter size in sows weaned at two different average weaning ages. No significant lactation length treatment differences were observed for WSI, WCI, or subsequent litter size. This study indicates that producers should be able to choose weaning ages in the range of 15 to 20 d without any negative impacts on sow reproductive performance. Thus, when producers are making weaning age decisions they must consider what the best decision is for the entire production system.