1. Introduction

Necrotic enteritis is an important disease in poultry due to the high economical losses it causes. It is an acute enterotoxemic caused by toxins secreted by Clostridium perfringens.

There are natural solutions, based on the cimenol ring, a natural aromatic compound obtained from botanical extracts, which has proven its effect as an intestinal microbicide, and helps to prevent multiple bacterial diseases such as necrotic enteritis.

2. Objective

To evaluate the effect of the cimenol ring on the prevention of necrotic enteritis in broiler defied with pathogenic strains of C. perfringens.

3. Material and methods

A total of 160 male broiler Vencobb 430 were used, from day 1 to day 35 of life. The animals were divided into the following experimental groups, following a random block design:

1. Negative control: basal diet (DB) of the farm.
2. Infected control: basal diet (DB) + challenge with C. perfringens.
3. Cimenol group: basal diet (DB) + cimenol ring at a dose of 1 g/kg
4. Experimental group: basal diet (DB) + cimenol ring at a dose of 1 g/kg + challenge with C. perfringens.

There was a total of 4 replicates per treatment with 10 animals each. The basal diet did not contain any antimicrobial or coccidiostatc and was formulated with 23.5% protein and 5% meat and bone meal. Drinking water did not contain antimicrobial agents either.

The challenge was made with pathogenic strains of Clostridium perfringens obtained from intestinal tissue samples from birds with symptomatology compatible with necrotic enteritis. The samples were grown in anaerobiosis and CFU counting was performed from the inoculum obtained.

The animals were challenged on days 14, 15 and 16, orally and individually with a 1 ml of inoculum at a concentration of 1 x 10⁸ CFUs/bird. Access to food was restricted for 4 hours before the challenge and access to drinking water during the previous 2 hours.

4. Results

When weekly weight of the animals was assessed, lower growth in the batches challenged with C. perfringens was observed from the third week of trial. Finally, after 35 weeks of trial, the groups with cimenol ring were the ones that obtained the highest final weight and the group with

cimenol ring and without challenge obtained the greatest weight, and the infected control the one that obtained a lower weight.

Table 1. Weekly weight (g) obtained in each experimental group throughout the trial. *Indicates tendency (P<0.10)

At the same time, feed consumption was assessed over the course of the trial, with a marked reduction in consumption in the infected group without cimenol ring.

Tables 2 and 3. Feed consumption (g) and feed conversion rate (FCR) obtained in the four experimental groups. *Indicates tendency (P<0.10).

As in the case of weekly weight, the best results in relation to the feed conversion rate were obtained in those groups supplemented with cimenol ring, which obtained a significantly lower value than the non-infected control group.

Regarding the survival rate, the group with cimenol ring and without challenge was the one that obtained the best result, with 100% survival, while the infected control group obtained the worst result, with 90% survival. The negative control group and the experimental group got the same survival rate, 97.5%

Table 4. Survival percentage and efficiency rate obtained during the test. Letters indicate statistically significant differences (P<0.05).

The efficiency index was significantly higher in the group with cimenol ring and without challenge. At the same time, a significant difference was observed between the infected control group and the experimental group, both challenged with pathogenic strains of C. perfringens.

The degree of intestinal injury was determined in all experimental groups to evaluate the status of the mucosa, the viscosity of the content and the presence of undigested food, on a scale of 0-3, where 0 corresponded to the absence of lesions and 3 with the presence of severe lesions. The groups supplemented with the cimenol ring obtained a lower degree of intestinal injury.

Image 1. Evaluation of the degree of injury to the mucosa of the small intestine.

At the same time the integrity of the mucosa and the presence of lesions compatible with necrotic enteritis in the small intestine were evaluated at 5 days post-infection.

Image 2. Evaluation of lesions compatible with necrotic enteritis in the different experimental groups.

Image 3. Evaluation of intestinal tissue samples from tested experimental groups.

5. Conclusion

On one hand, the use of the cimenol ring in the absence of a challenge allows to improve the productive parameters of the farm, due to the positive effect of the cimenol ring on the intestinal flora.

On the other hand,  the use of the cimenol ring is effective as a preventive treatment against a challenge with C. perfringens as it normalizes the productive parameters in infected birds and achieves similar values to those observed in the control group and, at the same, prevents the appearance of intestinal lesions.

The cimenol ring is marketed under the name Alquermold Natural from Biovet S.A.