MIC and MBC results of microencapsulated products against C. perfringens in vitro

The antimicrobial activity of microencapsulated products (C8–C12–C14, C12–C14 and C10–C12) and avilamycin against four strains of C. perfringens: CP-D25, CP-MZ1, CP-C8-1 and CP-CVCC52 (quality control) in vitro were tested using MIC and MBC. As shown in Table 1, the MIC value of C8–C12–C14 against CP-D25, CP-MZ1, CP-C8-1 and CP-CVCC52 were 0.1 mg/mL, 0.1 mg/mL, 0.5 mg/mL and 0.2 mg/mL respectively, and the MBC values were 0.1 mg/mL, 0.2 mg/mL, 1.0 mg/mL and 0.2 mg/mL respectively. The MIC values of C12-C14 against CP-D25, CP-MZ1, CP-C8-1 and CP-CVCC52 were 0.00625 mg/mL, 0.0125 mg/mL, 0.00625 mg/mL and 0.003125 mg/mL respectively, and the MBC values were 0.05 mg/mL in all groups. The MIC value of C10-C12 against CP-D25, CP-MZ1, CP-C8-1 and CP-CVCC52 were 0.05 mg/mL, 0.05 mg/mL, 0.5 mg/mL and 0.025 mg/mL respectively, while the MBC values were 0.1 mg/mL, 0.1 mg/mL, 0.5 mg/mL and 0.1 mg/mL respectively. In addition, the MIC value of avilamycin against CP-D25 and CP-CVCC52 were 0.00625 mg/mL, and the MBC values were 0.05 mg/mL, however, CP-MZ1 and CP-C8-1 were found to resistant to avilamycin.

Table 1 MICs and MBCs of different treatments against different strains of C. perfringensEffect of microencapsulated products on growth performance in broiler chickens

The results of the relative weight gain (RWG) and survival rate (SR) are shown in Fig. 1A and B. There was no significant difference in SR and RWG among all treatment groups compared with the negative control (no additive supplementation and no challenge) group. The challenge group (CC) with no treatment showed a significant decrease in the SR (66.67 ± 4.76%, p < 0.0001) and RWG (76.56 ± 1.03%, p < 0.0001) compared to the negative control group (100.00% ± 0.00), which is shown in Table 2.

Fig. 1

Comparative values of the relative weight gain (RWG), survival rate (SR), lesion score of duodenum and jejunum. A relative weight gain (RWG) in birds of different treatments. B survival rate (SR) in birds of different treatments. C lesion score of duodenums in birds of different treatments. D lesion score of jejunums in birds of different treatments. PC avilamycin-positive control. CC challenge control. NC no additive supplementation and no challenge. Astricts signify statistical significance in comparison to the control group (*p < 0.05, **p < 0.005, ***p < 0.0005, ****p < 0.0001)

Table 2 Comparative values of the survival rate (SR), relative weight gain (RWG), lesion score of duodenum and jejunumEffect of microencapsulated products on gross lesions in broiler chickens

The results of gross lesions of duodenum and jejunum are shown in Fig. 1C and D. The NE lesion scores of duodenum and jejunum in the high dose of C8–C12–C14 (1.43 ± 0.23, p < 0.0001; 0.48 ± 0.13, p < 0.05), C12–C14 (1.52 ± 0.19, p < 0.0005; 0.48 ± 0.11, p < 0.05), C10–C12 (1.72 ± 0.24, p < 0.005; 0.44 ± 0.15, p < 0.05), Avilamycin-positive control (1.35 ± 0.18, p < 0.0001; 0.2 ± 0.09, p < 0.005), and NC (1.32 ± 0.19, p < 0.0001; 0.26 ± 0.10, p < 0.005) groups were significantly lower compared to the CC group (2.86 ± 0.21; 1.20 ± 0.28). No significant difference was observed in the lesion scores of jejunums in low dose of C8–C12–C14 (0.67 ± 0.22, p > 0.05), C12–C14 (0.95 ± 0.22, p > 0.05) and C10–C12 (0.52 ± 0.21, p > 0.05) groups, which is shown in Table 2.