Effect of Different Ratios of Phytogenic Feed Additives in Weaned Pigs Challenged with a Pathogenic Escherichia Coli.

This study was conducted to investigate the effects of supplementing different ratios of phytogenic feed additive (PFA) to weaned pigs challenged with pathogenic Escherichia coli (E. coli) on growth performance, nutrient digestibility, intestinal barrier integrity, and immune response, and to determine the optimal mixing ratio for PWD prevention. A total of 48 four-week-old weaned pigs with initial body weight of 8.01 ± 0.39 kg were placed in individual metabolic cages, and then randomly assigned to eight treatment groups. The eight treatments were as follows: a basal diet without E. coli challenge (negative control, NC), a basal diet with E. coli challenge (positive control, PC), PC with supplementing 0.1% mixture of 20 % bitter citrus extract (BCE), 10% microencapsulated blend of thymol and carvacrol (MEO), and 70% excipient (T1), PC with supplementing 0.1% mixture of 10% MEO, 20% premixture of grape seed and grape marc extract, green tea, and hops (PGE), and 60% excipient (T2), PC with supplementing 0.1% mixture of 10% BCE, 10% MEO, 10% PGE, and 70% excipient (T3), PC with supplementing 0.1% mixture of 20% BCE, 20% MEO, and 60% excipient (T4), PC with supplementing 0.1 % mixture of 20% MEO, 20% PGE, and 60% excipient (T5), and PC with supplementing 0.1 % mixture of 10% BCE, 20% MEO, 10% PGE, and 60% excipient (T6; Table 1). The experiments were progressed in 16 days, including 5 days before and 11 days after the first E. coli challenge (d 0). In the E. coli challenge treatments, all pigs were orally inoculated by dividing a total of 10 mL of E. coli F 18 for 3 consecutive days from d 0 post-inoculation (PI). Compared with the PC group, the PFA2 and PFA6 groups significantly increased (P < 0.05) feed efficiency and decreased (P < 0.05; Table 2) diarrhea during the entire period (Table 3). At d 11 PI, the PFA6 group significantly improved (P < 0.05) gross energy digestibility compared with the PFA1 group (Table 4). The PFA6 group significantly decreased (P < 0.05) tumor necrosis factor a (TNF-a) and interleukin- 6 (IL-6) in serum (Table 5) and increased (P < 0.05) the villus height to crypt depth ratio (VH:CD; Table 6; Figure 1). The PFA2 significantly decreased (P < 0.05) the relative protein expression of calprotectin in the ileum (Table 7). In conclusion, improvements in growth performance, diarrhea reduction, and immunity enhancement are demonstrated when 10% BCE, 20% MEO, 10% PGE, and 60% excipient are mixed. [ABSTRACT FROM AUTHOR]