Understanding feeding patterns in growing pigs by modelling growth and motivation

Feeding is an essential behaviour for body maintenance in pigs and closely related to their growth and productivity performance. Mechanisms underlying feeding behaviour in pigs are still unclear. Understanding these mechanisms can provide valuable insights into the complex interactions among various factors affecting feeding behaviour and help to improve growth and productivity of pigs. The aim of this study was to increase our understanding of internal causation and development of short-term feeding patterns in a pig, and the relation between feeding patterns and productivity of a pig during the growth period. We developed a mechanistic simulation model that represents an individually housed growing pig. The model integrates knowledge from physiology and ethology, and combines growth with a behavioural decision model based on motivation. Combining growth with behaviour allowed exploring the development of a pig over time, in particular the causation of growth and feeding patterns over a 24 h period and during the entire growing period. Physiological factors, affected by pig and feed characteristics, are important internal factors controlling feeding behaviour. Model output included short-term feeding behaviours in pigs (e.g. meal size, meal frequency and meal duration), and growth characteristics (e.g. energy use, body weight gain). The model yielded feeding patterns that were validated against empirical data. This modelling study provided insight in how growth and motivation explain the development of feeding patterns of an individually housed pig over time. Pig and feed characteristics affected the motivation to reach a desired level of daily feed intake. Without feeding restrictions, pigs adapted feeding patterns to reach this daily feed intake without affecting growth. The developed model is suitable to further study mechanisms underlying feeding behaviour and performance of group-housed pigs.