Nematophagous fungus Duddingtonia flagrans NCIMB 30336 in feed for grazing animals: viable chlamydospores counted on YMA agar and by the MPN method, dose 3 × 10⁴ chlamydospores per kg body weight per day
Commission Implementing Regulation (EU) 2026/534, published on 12 March 2026, extends the authorisation of the preparation of Duddingtonia flagrans NCIMB 30336 from dairy cattle, sheep and goats to grazing cattle, sheep and goats other than dairy animals and to camelids, cervids, equines, pigs and rabbits — until 1 April 2036. The additive is meant to reduce the number of infective nematode larvae on pasture.
- Analytical methods in the annex: strain identification — DNA-based methods; viable chlamydospore count in the additive, premixtures and compound feed — plating on yeast mannitol agar (YMA) with streptomycin and chloramphenicol and calculation by the most probable number (MPN) method. The additive contains at least 5 × 10⁵ chlamydospores/g.
- Content in complete feed (12 % moisture), chlamydospores/kg: piglets 6.0 × 10⁵–1.2 × 10⁶, pigs for fattening 7.2 × 10⁵–1.4 × 10⁶, sows 8.8 × 10⁵–1.7 × 10⁶, rabbits 5.3 × 10⁵–1.1 × 10⁶, cows for reproduction and bulls 8.5 × 10⁵–8.5 × 10⁶, calves 1.4 × 10⁶–3.0 × 10⁶, cattle for fattening, sheep, goats, camelids, cervids and equines 1.3 × 10⁶–2.6 × 10⁶. The additive may be used only in feed for grazing animals.
- In its opinion of 20 March 2025 EFSA took the view that the chlamydospores practically do not germinate in the digestive tract: in vitro they did not germinate under anaerobic conditions or above 37 °C, and under optimal conditions (25 °C) they reach about 55 % germination only after about 36 hours. It therefore used a 90-day rat study (NOAEL 6 × 10⁶ chlamydospores/kg body weight per day) to assess safety for the animals.
- According to EFSA the additive is not irritant to skin or eyes but is irritant to the respiratory tract and a respiratory sensitiser; EFSA could not conclude on skin sensitisation. The regulation requires respiratory and skin protection where procedures do not eliminate the risks. On 18 June 2025 the applicant withdrew the application for the remaining grazing species.