Summary
Pigs were divided at weaning into 2 weight groups and 2 age groups and fed 3 different amounts of a Phase 1 diet to examine whether weaning feeding programs should be tailored to the age and/or weight of the pig. Bodyweight at weaning, but not age resulted in improved performance at day 53 post-weaning. Feeding program had no effect on growth or feed efficiency performance, or the variability in growth.

Introduction
Feeding the newly weaned pig is becoming an increasingly complex challenge, as multiple forces present themselves to pork producers. These forces include needs for lower cost, less antibiotic usage, improved performance and reduced variability. In this experiment, the impact of both the pig weight and age at weaning, as well as the quantity of each phase of diet offered to the pig were evaluated. We hypothesized that the lighter pig, and the younger pig within the lighter sub-group, would respond more to the higher quality diets; and therefore they would improve relative to similar pigs fed a poorer diet. This would result in improved overall performance and a reduction in body weight variability at the time of nursery exit.

Results and Discussion
Diet nor intake treatment affected performance (P > 0.05).> Initial body weight group affected final BW (Table 2), ADG (Table 3) and ADFI (Table 4) throughout the trial (P < 0.001). Initial age affected BW and feed intake, but surprisingly had no effect on ADG or feed efficiency. Within a weight block, the older pigs began the trial 40 to 70 grams heavier than the younger pigs. The effect of initial weight and age on BW was observed at each weigh point, but became less pronounced as the trial progressed. Heavier pigs consistently grew faster than lighter pigs, and older pigs generally grew faster than younger pigs. Similar results were observed for feed intake. The effects of initial body weight group and age on feed efficiency (Table 5) were inconsistent. Generally, heavier pigs used feed more efficiently than lighter pigs; this effect achieved significance by the second half of the experiment. However, by the final week of the experiment, pigs in the young treatment group tended to have an improved feed efficiency relative to those which were older at weaning. The coefficient of variability (CV) of body weight was calculated within pens (n = 8); therefore it is possible that single aberrant pigs may skew the result (Table 6) and these numbers are not representative of the CV of the weaning group. The CV was less for heavier pigs throughout the experiment. Since this effect was observed at d 0 it is a reflection of the variability observed with the light weight pigs at the experiment initiation. Age had no effect on CV. Implications Pigs which are heavier at weaning perform better than lighter pigs, regardless of age or intake of Phase 1 diet, which had only modest effects on performance. Acknowledgements Strategic funding provided by Sask Pork, Alberta Pork, Manitoba Pork and Saskatchewan Agriculture and Food Development Fund. Funding for this project Hamlet Protein, Denmark is gratefully appreciated.