Potential of Plant Extract to Improve Performance and Intestinal Health in Broilers during the Onset of Clinical Necrotic Enteritis

Plants extracts (PE) have shown promising effects on performance and intestinal health in broilers. Their potential as antimicrobial (AM) alternatives has been studied for years (Adhikari et al., 2020). A feeding study was conducted to examine the effect of a micro-encapsulated product composed of eugenol and garlic tincture on growth performance, mortality, intestinal lesions, jejunal gene expressions, and histology in broilers during the onset of necrotic enteritis (NE). A total of 960 d-old Cobb 500 broiler chicks of mixed sex were assigned to 48-floor pens each stocked with 20 birds. A randomised complete block design was used with 6 treatments replicated 8 times. The treatments were: UC- unchallenged control; CC- challenged control; PE- challenged group plus PE (100 g/t feed); AM- challenged group plus AM (625 g/t; narasin and nicarbazin; 50 ppm); FAP- challenged group plus full dose of AM with PE; HAPchallenged group plus half dose of AM (312.5 g/t; narasin and nicarbazin; 25 ppm) with PE in starter, grower and finisher phases. Diets were based on wheat, sorghum, soybean meal, and meat and bone meal supplemented with phytase. Birds were challenged according to Rodgers et al. (2015) by giving 1 mL per os field strains of Eimeria spp. oocysts consisting of E. acervulina (5000), E. maxima (5000) and E. brunetti (2500) on d 9 and 1 mL per os approximately 10⁸ CFU/mL of Clostridium perfringens (NE-18) on d 14. Mortality caused by NE was determined by necropsy. The sex of the birds was determined by high-resolution melting curve analysis (HRM) using feather crude DNA (England et al., 2020). Bird performance was measured from d 9 to 21(corrected to dead birds). Mortality (d 14 to 17), intestinal lesions, jejunal gene expressions (males and females), and histology (males) were measured on d 16. Data were subjected to one-way ANOVA analysis using JMP software.

Increased mortality (17.7%), reduced BWG and feed intake, and impaired FCR and higher intestinal lesions by the challenge (P < 0.05) indicate a successful clinical NE challenge. The treatments UC, AM, FAP, and HAP had higher BWG, lower mortality, and FCR, higher villus surface area (VSA), and goblet cell numbers (GCN) compared with CC (P < 0.05). Birds supplemented with PE had lower FCR compared with CC (P < 0.05). Birds fed PE had lower ileal lesions (P < 0.05), tended to lower jejunal lesions (P = 0.066) in male birds, and lower mortality (2.9%) compared with the CC group. The expressions of jejunal MUC2, OCLDN, CLDN1 and ZO1 were not different between PE group and different doses of AM groups in male and female birds (P > 0.05). Birds in PE group had higher GCN compared with CC (P < 0.05) and had similar VSA and GCN compared with HAP group (P > 0.05). These findings suggest that different combinations of a PE with antimicrobials were effective in alleviating the impact of clinical NE as indicated by improved performance and health traits. These results also demonstrated that PE supplementation in the diet helps to improve feed efficiency, reduce mortality and intestinal lesions, and increase GCN when birds are infected with NE.