Background This study was conducted to investigate the effects of each phytogenic feed additive (PFA; PFA1, bitter citrus extract; PFA2, a microencapsulated blend of thymol and carvacrol; PFA3, a mixture of bitter citrus extract, thymol, and carvacrol; PFA4, a premixture of grape seed, grape marc extract, green tea, and hops; PFA5, fenugreek seed powder) on the growth performance, nutrient digestibility, intestinal morphology, and immune response in weaned pigs infected with Escherichia coli (E. coli). Results A total of 63 4-week-old weaned pigs were placed in individual metabolic cages and assigned to seven treatment groups. The seven treatments were as follows: 1) NC; basal diet without E. coli challenge, 2) PC; basal diet with E. coli challenge, 3) T1; PC + 0.04% PFA1, 4) T2; PC + 0.01% PFA2, 5) T3; PC + 0.10% PFA3, 6) T4; PC + 0.04% PFA4, 7) T5; PC + 0.10% PFA5. The experiments lasted in 21 d, including 7 d before and 14 d after the first E. coli challenge. In the E. coli challenge treatments, all pigs were orally inoculated by dividing a total of 10 mL of E. coli F18 for 3 consecutive days. The PFA-added groups significantly increased (P < 0.05) average daily gain and feed efficiency and decreased (P < 0.05) the fecal score at d 0 to 14 post-inoculation (PI). Tumor necrosis factor α was significantly lower (P < 0.05) in the PFA-added groups except for T1 in d 14 PI compared to the PC treatment. The T3 had a higher (P < 0.05) immunoglobulin G and immunoglobulin A concentration compared to the PC treatment at d 7 PI. Also, T3 showed significantly higher (P < 0.05) villus height:crypt depth and claudin 1 expression in ileal mucosa, and significantly down-regulated (P < 0.05) the expression of calprotectin compared to the PC treatment. Conclusions Supplementation of PFA in weaned pigs challenged with E. coli alleviated the negative effects of E. coli and improved growth performance. Among them, the mixed additive of bitter citrus extract, thymol, and carvacrol showed the most effective results, improving immune response, intestinal morphology, and expression of tight junctions.

The objective of this study was to evaluate the effects of different mixing ratios of Bacillus licheniformis and Bacillus subtilis in diets on nutrient digestibility, fecal microflora, and odor gas emissions of growing pigs. A total of four crossbred ([Landrace × Yorkshire] × Duroc) barrows with average body weight (BW) of 41.2 ± 0.7 kg were randomly allotted four diets over four periods in a 4 × 4 Latin square design. Treatments were as follows: Control (CON, basal diet), CON + 0.2% probiotic complex (L4S6, B. licheniformis and B. subtilis at a 4:6 ratio), CON + 0.2% probiotic complex (L5S5, B. licheniformis and B. subtilis at a 5:5 ratio), CON + 0.2% probiotic complex (L6S4, B. licheniformis and B. subtilis at a 6:4 ratio). Dietary probiotic supplementation showed higher crude protein (CP) digestibility values and lower Escherichia coli counts in fecal samples than the CON group ( p < 0.05). There was no significant difference in NH 3 or H 2 S emission until day 3. The positive effect of H 2 S and NH 3 emissions was detected earlier with the L4S6 and L5S5 compared to the L6S4, which had a lower ratio of B. subtilis . Both the L4S6 and L5S5 probiotic complexes significantly decreased the fecal H 2 S and NH 3 emission in days 4 and 6 ( p < 0.05). On day 7, all probiotic complexes decreased ( p < 0.05) H 2 S and NH 3 emissions than the CON group. Our results agreed that the dietary supplementation of Bacillus licheniformis and Bacillus subtilis complexes in growing pigs can significantly improve CP digestibility and reduce fecal E. coli counts, NH 3 and H 2 S emissions. Notably, the higher mixing ratio of Bacillus subtilis in probiotic supplementation is more effective in reducing the odor of manure.

Background Two experiments were conducted to establish an optimal NE challenge model and evaluate the efficacy of stimbiotic (STB) supplementation in necrotic enteritis (NE) challenged broilers. In Exp. 1, a total of 120 Arbor Acres (AA) broilers (45.0 ± 0.21 g) were randomly assigned to 6 treatments in a 3 × 2 factorial arrangement. Vaccine treatments included non-challenge (0), × 10 the recommended dose (× 10) or × 20 the recommended dose (× 20) by the manufacturer. Clostridium perfringens (CP) treatments were non-challenge (No) or 3 mL of 2.2 × 107 CFU CP challenge (Yes). In Exp. 2, a total of 72 AA broilers (40.17 ± 0.27 g) were randomly assigned to 6 treatments in a 3 × 2 factorial arrangement. Dietary treatments included non-additive (CON), 100 mg/kg STB (STB) and 100 mg/kg STB on top of a typical commercial blend including an essential oil, probiotics, and enzyme (CB). Challenge treatments included non-NE challenge (No) and NE challenge (Yes) as established in Exp. 1. Results In Exp. 1, CP and vaccine challenge decreased (P < 0.05) body weight (BW), body weight gain (BWG) and feed intake (FI), and increased (P < 0.05) the number of broilers with diarrhea and intestinal lesions. The oral administration of × 20 recommended dose of vaccines coupled with 3 mL of 2.2 × 107 CFU CP resulted in (P < 0.01) a significantly increased incidence of wet litter and intestinal lesions. Thus, this treatment was chosen as the challenge model for the successful inducement of NE in Exp. 2. In Exp. 2, the NE challenge negatively affected (P < 0.01) growth performance, ileal morphology, immunoglobulin contents in blood, caecal microbiota in the caecum, footpad dermatitis, intestinal lesion scores, tumour necrosis factor (TNF-α) and endotoxin in the serum compared with the non-NE challenged birds. The supplementation of STB and CB in diets enhanced (P < 0.05) growth performance, intestinal microbiota, and blood profiles by stimulating ileal morphology (VH and VH:CD) and propionate production in the cecum, and there were no differences in measured variables between STB and CB supplemented birds. Conclusion Overall, these results indicate that STB supplementation was able to reduce the inflammatory response and improve the performance of NE challenged birds, and the supplementation of STB alone was as effective as a typical commercial blend containing a number of other additives.

One hundred twenty weaned piglets (9.34 ± 0.74 kg) were used in a four-week experiment to investigate the effects of replacing medical ZnO with a different ratio of inorganic and organic zinc (IZ:OZ) or a low-crude-protein diet (LP) with mixed feed additives (MFAs) in the weaned piglets’ diet. The dietary treatments included a control (CON), T1 (T1; ZnO 1000 mg/kg), T2 (IZ:OZ 850:150), T3 (IZ:OZ 700:300), T4 (IZ:OZ, 500:500), and T5 (LP with MFAs (0.1% essential oils + 0.08% protease + 0.02% xylanase)). The growth performance was decreased (p < 0.05) in the CON treatment compared with the T4 treatment. The diarrhea incidence was decreased (p < 0.05) in the T4 and the T5 treatment compared with the CON and the T1 treatments. The apparent total tract digestibility (ATTD) of nutrients were increased (p < 0.05) in the T4 and T5 treatments compared with the CON, T1, and T2 treatments. The T4 treatment had a higher (p < 0.05) ATTD of zinc than the T1, T2, and T3 treatments. The fecal microflora was improved (p < 0.05) in the T5 treatment compared with the CON and T3 treatments. In conclusion, IZ:OZ 500:500 could improve growth performance, nutrient digestibility, and zinc utilization while reducing diarrhea incidence in weaned piglets. Moreover, LP with MFA could replace medical ZnO.

Competing interestsNo potential conflict of interest relevant to this article was reported.