Natural oregano essential oil-based feed additive as an alternative to anthelmintics

Q: What impact did the inclusion of natural oregano oil-based feed additive have on helminth infections at the end of the rearing and laying phases?

The inclusion of a natural oregano oil-based feed additive numerically reduced helminth infections at the end of the rearing and laying phases.

Q: How did natural oregano oil contribute to intestinal health in laying hens according to the study?

Rajkovic et al., (2019) showed carvacrol, a main active component of natural oregano oil, to be effective against large roundworms taken from the intestines of laying hens, with no evidence of resistance.

Q: What improvements were observed in pullets when fed diets supplemented with natural oregano oil?

In a recent experiment (Lund et al., 2020), intestinal morphology was improved in pullets fed diets supplemented with 300g/tonne OS.

I. INTRODUCTION

Consumer demand for organic and free-range poultry products is driving the commercial egg industry away from conventional housing systems towards free-range housing systems that allow birds access to the outdoors. Whilst these systems are considered higher welfare, they also carry more health risks that can impact the intestinal health of the bird, such as greater exposure to parasites as reported by Permin et al., (1999). Intestinal helminths such as nematodes and tapeworms may reduce hen performance and transmit disease. Challenges with preventing and treating such helminth infections include increasing resistance to anthelmintics and a limited number of anthelmintics available for laying hens. Therefore, finding alternatives for mitigating helminth infections and maintaining hen performance in free-range housing systems is important for production efficiency and hen welfare. Anti-parasitic properties of oregano essential oil have been reported previously (Force et al., 2000).

This study was conducted to provide an evaluation of feeding Orego-Stim®, OS to a brown egg breed, Bovans Brown (BB), in a free-range system, on intestinal helminth loads, egg production and egg quality characteristics.

II. METHOD

Pullets were fed either a Control (corn/SBM diet) or supplemented diet (Control + OS (300g/tonne)) and were brooded and reared on slats until 12 weeks of age and then allowed on range through to 16 weeks, followed by the laying phase on range (929 cm² /pullet) from 17-41 weeks of age. The laying phase had three dietary treatment groups as follows: (1) Control in rearing phase (C) + Control in laying phase (C), CC; (2): Control in rearing phase (C) + OS in laying phase (O), CO; and (3) OS in rearing phase (O) + OS in laying phase (O), OO. Five hundred and forty hens were reared in a conventional slatted system, then allowed on range with a mix of summer and winter forages that provided three replicates per treatment in the production phase. Biweekly performance data was taken during rearing and laying phases. Tapeworm, large roundworm, and caecal roundworm burden was measured at 16 weeks, just before the laying phase, and termination of the trial at 41 weeks by screening the intestinal contents of 10 hens from each treatment for adult helminths.

III. RESULTS

At the end of the rearing phase, no large roundworms or tapeworms were observed in any of the hens, but caecal roundworms were observed in lower numbers in pullets on O diet rather than C (P > 0.05) (Table 1).

There was no difference observed in pullet days (pullet number x days in rear), mortality, pullet end body weight, pullet body weight gain, feed consumption per pullet per day or feed conversion (g feed/g gain) in rearing phase between treatments (P > 0.05).

Table 1 - Rearing phase helminth summary.

Large roundworm, caecal roundworm, and tapeworms were observed in all 3 treatment groups at 41 weeks. A lower count of caecal and large roundworms were observed in hens in OO group compared to CO and CC groups (P > 0.05). Fewer hens in OO and CO groups were infected with tapeworms compared to CC hens (P > 0.05) (Table 2).

In the laying phase, there was no difference in egg production percent (hen day or hen house), egg weight or age at 50 % production between treatments (P > 0.05). Feed consumption was lower for OO and CO than CC (P < 0.05) and the overall feed conversion (kg feed consumption/dozen eggs) was six points lower (P < 0.05) for OO and CO than CC (Table 3). A larger proportion of USDA Grade A eggs (P < 0.05) were produced for OO than CO and CC (Table 4).

Table 2 - Laying phase helminth summary.

Table 3 - Laying phase production summary.

Table 4 - Laying phase egg quality summary.

IV. DISCUSSION

The inclusion of a natural oregano oil-based feed additive numerically reduced helminth infections at the end of the rearing and laying phases. The anti-parasitic properties of plants are well characterized in vivo (Dhama et al., 2015), where natural oregano oil has been shown to significantly reduce gut lesion scores caused by intestinal parasite, Eimeria spp. in broilers (Giannenas et al., 2003). Natural oregano oil is documented to contain over 100 active components which together have a complex mode of action, exhibiting anti-microbial, antioxidant and anti-inflammatory properties (Gheisar and Kim, 2018). Rajkovic et al., (2019) showed carvacrol, a main active component of natural oregano oil, to be effective against large roundworms taken from the intestines of laying hens, with no evidence of resistance.

The most common genera of roundworms and tapeworms in poultry reside in the intestine and/or caeca. Infection can cause damage to the intestinal mucosa, reducing feed efficiency and subsequent egg production. In this study, feed conversion efficiency was improved by six points (P < 0.05) when hens were supplemented with natural oregano oil in either rearing or laying phase. In a recent experiment (Lund et al., 2020), intestinal morphology was improved in pullets fed diets supplemented with 300g/tonne OS. Supplemented pullets had increased villus height, deeper crypt depth and thicker intestinal lining, indicating better digestive function. Other studies in poultry have reported improved gut morphology and beneficial modulation of the gut microbiota following dietary supplementation with natural oregano oil at the same concentration as that used in this study (Mohiti-Asli and GhanaatparastRashi, 2018; Soliman et al., 2016). Whilst intestinal health parameters were not assessed in this study, previous work would suggest natural oregano oil may have helped in improving feed efficiency and egg quality.

In conclusion, the inclusion of a natural oregano oil-based feed additive either during both rearing and laying phases, or the laying phase only, reduced helminth infections, whilst improving feed efficiency and egg quality. The use of natural oregano oil in free range poultry systems offers a potential tool for mitigating helminth infections and maintaining hen performance, which can be used to support conventional worm control programmes.

Presented at the 34th Annual Australian Poultry Science Symposium 2023. For information on the next edition, click here.