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Abstract The activation of the immune system reduces the nutrient availability for growth and increases the variability among pigs. Functional amino acids (AA) supplementation can reduce the negative effects of immune activation. Additionally, providing daily tailored diets using individual precision feeding (IPF) was shown to account for individual variability. Therefore, we hypothesized that the association of IPF and functional AA supplementation could reduce the negative effect of immune-challenged pigs fed with daily tailored diets. The aim of this study was to assess performance and blood parameters variation of growing pigs under poor sanitary conditions while being fed functional AA 120% above the estimated INRA AA ratios within IPF, compared with a conventional group-phase (GP) feeding system. The sanitary condition was characterized by oral inoculation of 2 × 109 cfu of Salmonella typhimurium and manure spreading on the pen floor on d 0. Sixty gilts (23 ± 2.8 kg body weight; BW) were distributed in a complete randomized block design in a 2 x 2 factorial arrangement composed of 2 diets: CN with 100% INRA AA ratio or AA+ with 120% of the ratio for Met, Thr and Trp; and 2 feeding systems: GP or IPF. GP pigs received a single diet matching the SID Lys requirement of the 80th-percentile pig at the beginning of the trial whereas IPF pigs received a diet tailored daily to each pig requirement. All pigs were group-housed and fed ad libitum for 28 d by automatic feeders. Body weight was measured at d 0 and 28 and feed intake was recorded daily. Blood samples were collected at d 0, 7 and 28. Data were analyzed with diet and feeding systems and their interactions as fixed effects and BW blocks as random effect. Blood parameters were analyzed as repeated measurements over time. The pig was considered the experimental unit. No diet effect or interactions were observed for any variable (P 0.05), suggesting that only supplementing Met, Trp, and Thr is not enough to support growth during a sanitary challenge (Table 1). Haptoglobin and IgG increased linearly whereas IgA, urea, and creatinine had a quadratic increase over time (P 0.05; Table 2). The IPF decreased growth performance and increased serum IgA and creatinine (P 0.05), mostly due to the fact that IPF reduces AA provision compared with GP system. The IPF model, as most mathematical models, does not account for the AA and energy costs related to the immune challenge. Therefore, IPF might have underestimated the requirements of the pigs, and limited the amount of nutrients provided. In conclusion, the combined effect of IPF and functional AA supplementation was not able to reduce the negative effect of the sanitary challenge.
Arnaut et al. (Wed,) studied this question.