Animal Industry Report

Extension Number

ASL R2733



Summary and Implications

Numerous factors, including birth weight, can affect transition during weaning. The objective of this experiment was to evaluate the effects of birth weight and transition ADG on growth and nutrient digestibility of pigs reared in a commercial environment. A total of 1,500 pigs were weighed at birth, tagged, and divided into 5 birth weight categories: <1 kg, 1-1.25 kg, 1.25-1.5 kg, 1.5-1.75 kg, >1.75 kg. At weaning, 1,054 pigs were moved to a commercial wean-to-finish research barn. All pigs were weighed individually at 0, 3, 6, and 22-weeks post-weaning. Gain from 0 to 3-weeks post-weaning was calculated and termed ‘transition ADG.’ Pigs from 3 transition ADG percentiles were of interest: 10th, 30th, and 70th. Forty pigs from each of these three transition ADG categories were matched for sex, litter number born alive, and sow parity to create 20 matched sets for 60 total pigs. At 3-weeks post-weaning, the 20 sets of pigs were harvested for whole-body carcass composition, and rectal digesta samples were collected to determine nutrient digestibility. All other pigs remained in the barn and were raised under typical commercial conditions. Data were analyzed using PROC GLIMMIX. There were no birth weight × transition ADG interactions (P > 0.27). Birth weight affected (P < 0.05) all weight and ADG periods except ADG from weaning to 3-weeks postweaning (P = 0.78). Transition ADG affected (P < 0.0003) all weight and ADG periods. In particular, pigs from the 10th percentile were nearly 5 kg lighter than pigs from the 70th percentile by week 6 post-weaning, and over10 kg lighter by 22 post-weaning. There was no effect (P > 0.11) of birth weight or transition ADG on nutrient digestibility or carcass composition. In conclusion, both light birth weight and post-weaning failure is a substantial source of weight variation at closeout, but this variation cannot be attributed to differences in nutrient digestibility.

Copyright Holder

Iowa State University