PhD ThesisDuring the production period from birth to slaughter there are some pigs that grow
markedly slower, despite conditions that seem to support the rapid growth of their
contemporaries. This reduction in growth inevitably leads to weight variation within a
group and results in system inefficiencies. The aim of this thesis was to identify risk
factors involved in poor growth and to develop management and nutritional treatments
to enable light pigs to maximise their growth at different stages of production.
Risk factor analysis for a large dataset showed that, in particular, low birth and weaning
weight result in poor growth to finishing. Some light pigs do, however, have the
capacity to compensate for low weight at earlier stages of production. Preweaning
intervention demonstrated that low birth weight pigs cross fostered into litters with
similar weight littermates had a significantly higher weaning weight than those in mixed
litters with heavier pigs; however the provision of supplementary milk to such litters
had no further beneficial effect. A post weaning feeding regime formulated for low birth
weight pigs, with a higher nutrient specification diet based on more digestible
ingredients, not only showed improved performance to 10 weeks of age, but also
enabled low birth weight pigs to meet the BW of heavier birth weight pigs. In contrast,
a high specification diet (higher in amino acid: energy content) had no effect on the
growth of low birth weight pigs when offered from 9 weeks of age, suggesting a critical
window for intervention.
Overall, the crucial stages of postnatal growth for light pigs have been identified, and
preweaning and early post weaning treatments have been developed. These not only
improve the performance of low birth weight pigs but also allow them to catch up with
heavier birth weight pigs