Elucidating the Impact of Feeding Behaviour on Body Composition in Finishing Pigs Fed Ad Libitum Using an Integrative Feeding Behaviour Index

Abstract Background: Large variability in body composition is observed in pigs fed and raised in similar conditions. Part of this variation might be explained by the feeding behavior of pigs, given its effect on metabolic hormones associated with energy regulation and protein metabolism. The objective of this study was to elucidate this relationship by examining body composition with a new index describing feeding behavior in finishing pigs. Feeding behavior and body composition information on 138 pigs during the last 28 d of the growing phase from three trials were used. For each pig, the sum of the areas between the observed relative cumulative feed intake and the regression line for the evolution of relative feed intake over time was used to calculate the new feeding behavior index. This index quantifies the irregularity of feed intake (IIFI) by integrating different components of feeding behavior into a single measurement. Body lipids and protein composition were estimated by dual X-ray densitometry at the beginning (day 1) and end of the finishing phase (day 28). Results: Weak to moderate correlations (r = ±0.31 to ±0.44; P < 0.05) of IIFI with body composition and performance variables were found only in datasets 1 and 2. However, in dataset 2, IIFI was also correlated with daily feed intake (r = - 0.54; P < 0.001). Irregular feeding behavior is associated to increased proportion of protein (PdDG) and decreased proportion of lipids (LdDG) in body gain. However, IIFI only accounted for 8% to 14% and 10% to 12% of the total variation of PdDG and LdDG in datasets 2 and 1, respectively. Additionally, factor analysis showed that the number of meals and IIFI had high loadings in a factor separate from factors associated with body composition or performance, suggesting that body composition and performance are independent of feeding behavior. Conclusion: Factors other than feeding behavior might be involved in modulating body composition of finishing pigs fed ad libitum.