Effects of precision feeding and functional amino acid supplementation on Salmonella-challenged growing pigs under poor housing conditions

Immune system activation impairs pigs' growth and increases population variability. Individual precision feeding (IPF) takes into account the variability between pigs and improves the efficiency of nutrient utilization. Additionally, functional amino acid (FAA) supplementation reduces the negative impacts of immune system activation. However, the combined effect of IPF and FAA supplementation for immune-challenged pigs remains to be evaluated. We hypothesized that the combined effect of IPF and FAA supplementation would increase nutrient efficiency and reduce the effects of immune activation on pig performance. Therefore, the objective of this study was to evaluate the use of IPF and FAA supplementation on growth performance, body composition, nutrient efficiency, and the blood parameters in growing pigs raised under different sanitary conditions (SC). A total of 120 female pigs were used across two experiments. The pigs were assigned to a good (GSC) or poor (PSC) sanitary condition barns, each with 60 pigs. The GSC barn followed strict biosecurity protocols. In the PSC barn, pigs were orally inoculated with Salmonella Typhimurium and manure from a commercial swine farm was spread on the pen floor. In each SC barn, pigs were assigned to treatments arranged in a 2 × 2 factorial design. The treatments consisted of two feeding systems (FS): group-phase feeding (GPF) and individual precision feeding (IPF), and two diets: control (CN) with 100% or supplemented (AA+) with 120% of the SID Met + Cys, Thr, and Trp to Lys ratios above Inraporc recommendations. All pigs had ad libitum access to water and feed during the 28-d experimental period. The PSC increased rectal temperature and haptoglobin concentration compared with d 0 (P < 0.05). The IPF impaired the growth performance and body composition under GSC and PSC (P < 0.05). The performance of IPF pigs increased when fed AA+ diets under GSC, but no dietary effects were observed under PSC (P > 0.05). Group-phase feeding pigs ingested more SID Lys under both SC but had the same Lys efficiency of IPF under PSC (P > 0.05). Large fluctuations in body weight and daily feed intake might have impaired the IPF model's ability to estimate SID Lys requirements. In conclusion, FAA supplementation above the InraPorc recommendations did not mitigate the adverse effects of immune challenge on growth performance or improve nutrient utilization efficiency in IPF pigs.