Safety and efficacy of a feed additive consisting of a preparation of essential oils of thyme and star anise, and quillaja bark powder (BIOSTRONG® 510 all natural) for all poultry species (Delacon Biotechnik GmbH)

3.1.2. Characterisation of the active substances

The active substances in BIOSTRONG® 510 all natural predominantly derive from the thyme oil, star anise oil and quillaja bark. The crushed herbs and spices are also expected to contribute to the activity of the additive but to a lesser extent. Thymol is selected as the phytochemical marker.

Essential oil of thyme is obtained ■■■■■ The major component is thymol ■■■■■ with carvacrol ■■■■■.

Star anise oil from Illicium verum L. is obtained ■■■■■. ²⁰ The major component is trans‐anethole ■■■■■, with cis‐anethole representing ■■■■■.

Quillaja bark powder contains ■■■■■ saponins, which consist primarily of glycosides of quillaic acid. A content of tannins to a maximum of 8% dry matter has been reported for quillaja bark extracts (WHO, 2005). Quillaja extract (E 999) is approved as food additive under Regulation (EU) 1129/2011. ²¹

3.1.3. Physical properties of the additive

The additive BIOSTRONG® 510 all natural has a density of 1,000 kg/m³ and a bulk density of 520 kg/m³ ■■■■■, and a foam index of ■■■■■.

Stauber–Heubach data of three batches indicate a dusting potential ranging between 1.72 and 2.22 g/m³. The particle size of the dust was measured by laser diffraction in the same batches. The fractions of particles < 1, 10 and 50 μm were 4.35%, 54.6% and 99.9% (v/v), respectively. No particles < 0.1 μm were detected. ²²

3.1.4. Manufacturing process

BIOSTRONG® 510 all natural is manufactured by ■■■■■ ²³

3.1.5. Stability and homogeneity

The stability of the additive and feed containing the additive was assessed by monitoring the content of thymol.

3.2.1. Absorption, distribution, metabolism, excretion and residues

3.2.2. Toxicology

Star anise oil contains estragole (■■■■■) a compound with experimentally proven genotoxicity and carcinogenicity in rodents (as reviewed in EC, 2001; EMA, 2019). ■■■■■ EFSA compendium of botanicals ¹³ ).

Estragole was included in the diet of female CD‐1 mice at 0, 2.3 or 4.6 g/kg diet for 12 months. At least 50% of the animals in the exposed groups developed hepatic tumours by 18 months, ²⁸ which were diagnosed as hepatoma types A (hepatocellular adenomas) or B (hepatocellular adenocarcinomas) or mixed types A and B. The animals fed the control diet did not show any hepatic tumour (Miller et al., 1983, as referenced in EC, 2001a). The FEEDAP Panel notes that there is high uncertainty in deriving a benchmark dose (BMD) lower confidence limit for a benchmark response of 10% (BMDL₁₀) for estragole from a carcinogenicity study in CD‐1 mice. ²⁹

Since estragole ■■■■■ share the same mode of action as methyleugenol, all belonging to the group of p‐allylalkoxybenzenes, the FEEDAP Panel applies to estragole a BMDL₁₀ of 22.2 mg/kg body weight (bw) per day, derived from a carcinogenicity study in rat with methyleugenol (NTP, 2000) by applying model averaging (Suparmi et al., 2019) (for details, see EFSA FEEDAP Panel, 2022a). The FEEDAP Panel identified a no observed adverse effect level (NOAEL) of 10 mg/kg bw per day for non‐neoplastic lesions (effect on liver and the glandular stomach) from a 90‐day study in mice with methyleugenol (NTP, 2000), which is also applied to estragole and other p‐allylalkoxybenzenes (EFSA FEEDAP Panel, 2022b).

3.2.3. Safety for the target species

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3.2.4. Safety for the consumer

3.2.5. Safety for the user

3.3.1. Efficacy in laying hens

The applicant provided two short‐term and one long‐term efficacy trials in laying hens to support the safety for the target animals. BIOSTRONG 510® all natural is intended to be used as a zootechnical additive, under the functional groups of digestibility enhancers and other zootechnical additives (improvement of performance parameters). The efficacy of zootechnical additives intending to improve the productive performance of the animals needs to be demonstrated by means of long‐term efficacy trials, in agreement with the conditions established in the Guidance on the assessment of the efficacy of feed additives (EFSA FEEDAP Panel, 2018). ■■■■■

In the long‐term trial, 150 25‐week‐old laying hens (Lohmann Brown) were distributed in 30 pens of 5 hens each, and randomly allocated to three dietary treatments (10 replicates per treatment). ³⁵ The basal diet based on maize, wheat and soybean meal was either not supplemented (control) or supplemented with BIOSTRONG® 510 all natural to provide 150 or 1,500 mg/kg feed. The confirmation of the level of additive in feed was done by means of the analysis of thymol, considered as the reference marker. ³⁶ The experimental diets were offered ad libitum in mash form for 168 days, and included an external marker for the digestibility study.

Mortality and health status were checked daily, and the most likely cause of death or reason for culling was recorded. The laying hens were weighed at the start of the trial (day 1). Thereafter, the body weight and feed intake were weekly monitored. The number of eggs, unsaleable eggs (dirty, cracked, shell less eggs, roughed or soft shelled) and the egg weight were daily recorded. The laying rate, egg mass per hen and the feed to egg mass ratio were calculated per week and for the overall period. The eggshell strength and egg yolk colour were measured every week, while other egg quality parameters (Haugh unit and egg yolk index) on a monthly basis. At the end of the trial (day 168), the hen with the bodyweight closest to the average of the pen was selected (10 hens per treatment), killed and the ileal content extracted. The feed and ileal samples were analysed for the content of dry matter, crude protein, amino acids (lysine and methionine), crude fat, crude ash, calcium and phosphorus and the apparent ileal digestibility (AID) calculated.

The experimental data were analysed with an analysis of variance (ANOVA) with the treatment as fixed effect. A nonparametric Kruskal–Wallis test was applied when the normality of the data could not be assumed. Group means were compared with Tukey's test. Significance level was set at 0.05.

Mortality was 2%, 4% and 2% for the control, 150 and 1,500 mg/kg groups, respectively, and no differences were found between treatments. The supplementation of BIOSTRONG® 510 all natural at 150 and 1,500 mg/kg feed showed higher laying rate (Control = 90.97; 150 mg/kg = 92.03; 1,500 mg/kg = 92.05%) and better feed to egg mass ratio (2.20; 2.15; 2.12) compared to control. The group supplemented with 1,500 mg/kg also showed lower average daily feed intake (125.8; 125.0; 124.0 g) and higher egg weight (62.8; 63.3; 63.5 g) in comparison with the control. No detrimental effect of the additive was observed in any of the egg quality parameters measured or on the number of unsaleable eggs. The improvement of the laying performance observed was consistent with the higher AID of total amino acids, crude protein, crude ash, phosphorus and calcium observed in both supplemented groups in comparison with the control.