PSXI-22 - Different initial body weight and dietary supplementation of tryptophan, threonine, and methionine on feeding behavior index of growing pigs under a sanitary challenge

Abstract: Sanitary challenges (SC) can affect growth and revenue of pig production. The reduction in growth performance result from a decrease in daily feed intake (DFI). Besides, feeding behavior patterns may be also affected for pigs under SC. The extent of this impact might depend on the initial body weight (BW) of pigs. Additionally, supplementing tryptophan (Trp), threonine (Thr), and methionine (Met) above NRC requirements may attenuate inflammation and modulates DFI under SC. Therefore, this study aimed to evaluate initial BW variation and SC effect on feeding behavior of growing pigs fed supplemented diet with Trp, Thr, and Met at 100 or 120% of NRC recommended levels. Eighty gilts were categorized into two groups according to initial BW: light (23±0.8 kg) and heavy (29±1.0 kg). Both BW groups were group-housed for 14 days trial in a good or poor SC. Pigs within SC poor were orally inoculated with 2×10⁹ CFU of Salmonella Typhimurium, and fresh manure from a pig farm was spread on the floor. In contrast, pigs within SC good were not inoculated, nor was manure spread. Two diets (D) were provided within each SC: control (CN) or supplemented (AA+) diet with Trp, Thr, and Met:Lysine at 120% of NRC recommended levels. Pigs were individually fed through automatic feeders. Indexes of irregularity of feed intake (IIFI), meal duration (MD), and total intake (TI) were calculated based on real-time information registered by the feeders. For each pig, a monotonically increasing step function using relative cumulative DFI and relative time (after 14 days) was obtained, and linear regression models were fitted. The areas between the step function and the regression line were summed to obtain the IIFI. The means were compared using the MIXED procedure of SAS. There was an interaction for SCxD for TI, MD, and IIFI (P < 0.10, Table 1). Pigs within good SC fed AA+ had lower TI and shorter MD than CN diet (P < 0.05), however, pigs within poor SC fed CN or AA+ diet had no differences in TI and MD. Pigs within good SC fed AA+ had higher IIFI than CN diet, whereas pigs within poor SC fed CN had lower IIFI than AA+ diet (P < 0.05). Furthermore, BW influenced TI, and MD, as heavy pigs had a higher TI and MD than the light pigs (P=0.01), with no changes in IIFI (P >0.10). Pigs in poor SC had a greater IIFI meaning they had fewer longer meals and higher DFI compared to pigs in good SC. Increasing Trp, Thr, and Met ratio influenced the pigs feeding behavior likely due to changes in TI. Additionally, the IIFI may be a tool to detect on set SC due to salmonella infection.