Microencapsulated blends of botanicals are effective feed supplements to control necrotic enteritis caused by Clostridium perfringens in broiler chickens

Necrotic enteritis (NE) is one of the most common diseases in poultry production worldwide, leading to sub-optimal performance and considerable economic losses. Botanicals are progressively gaining importance as feed additives for their biological properties among which antibacterial and anticoccidial.

The aim of this study was to reproduce a NE challenge model caused by Eimeria coccidia and Clostridium perfringens (CP) in broilers and evaluate the effects of microencapsulated blends of botanicals in comparison with conventional drug treatments.

A total of 2,500 day-old chicks (Cobb500) were vaccinated for coccidiosis with Coccivac®-B52, divided in pens (50 birds/pen) and assigned to 5 groups (10 pens/group): CTR group, fed a control diet; AMP group, fed a diet with 100 ppm of Amprolium; BMD group, fed a diet with 55 ppm of bacitracin; TRT1, fed a diet supplemented with 400 g/MT of prototype 1; TRT2, fed a diet supplemented with Prototype 1 at 400 g/MT and Prototype 2 at 500 g/MT. Prototype 1 and Prototype 2 are a two microencapsulated blends of botanicals manufactured by Vetagro. All the animals were challenged first with cocci through an oral inoculation with Eimeria maxima (5,000 oocysts) at day 14, then with CP (alpha toxin and netB toxin positive, 10⁸ CFU) orally administered for 3 days (d19, 20, and 21). The study lasted 42 days with small intestine lesions scored at d21 from 3 birds/pen, fecal oocysts counted at d28 and growth performance recorded throughout the study. Data were analyzed with ANOVA and differences considered significant at P<0.05.

No differences in growth performance were observed before the challenge. From d14 to d28, immediately after the challenge, all the treated groups showed improved growth with higher weight gains and lower feed conversion ratio values compared to CTR group (P<0.01). In the overall period (0-42 days), the group TRT2 had the highest weight gain although only numerically (P=0.17), while FCR values were significantly reduced in particular by TRT2 and BMD (1.68 both) followed by TRT1 and AMP (1.73 both) compared to CTR group (1.84). All the treatments reduced overall mortality and mortality due to NE compared to CTR (P<0.0001). Compared to CTR, small intestine lesions score was reduced particularly by AMP and TRT2, while E. maxima counts were significantly lower only in TRT2 group (P<0.01).

In conclusion, the microencapsulated blends of botanicals used in this study have the potential to contain loss of performance and lesions associated with NE challenge in broiler chickens to the same extent of conventional drugs.

Keywords: Microencapsulation; botanicals; necrotic enteritis; C. perfringens; broilers

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