Weizmannia faecalis DSM 32016 (4b1900) authorised together with amprolium and narasin/nicarbazin: compatibility confirmed only after showing that spores without heat treatment at 80 °C germinate less and counting on MRS agar underestimates the result
Commission Implementing Regulation (EU) 2026/553, published on 16 March 2026, replaces the annexes to Regulations (EU) 2020/1755 and (EU) 2024/1054 for the spore preparation of Weizmannia faecalis DSM 32016 (formerly Bacillus coagulans; TechnoSpore50, holder: Biochem Zusatzstoffe Handels- und Produktionsges. mbH), adding amprolium and the combination of narasin with nicarbazin to the list of coccidiostats with which it may be used. In its 2023 opinion EFSA could not accept compatibility with narasin/nicarbazin; the opinion of 25 June 2025 revised that result on the basis of new data on spore germination.
- Methods in the annex (unchanged, the EURL did not draw up a new report): identification — DNA sequencing or PFGE (CEN/TS 17697); count in the additive, premixtures, compound feed and water for drinking — spread plate on MRS agar “based on EN 15787”, a standard developed for lactic acid bacteria. Additive: min. 2 × 10¹⁰ CFU/g of spores, 1 % silicic acid, the rest calcium carbonate. Three new batches: lead 0.78–0.81 mg/kg, arsenic 0.54–0.55 mg/kg, PCDD/Fs 0.17–0.33 ng WHO-TEQ/kg, nDL-PCBs 1.7–3.3 µg/kg, total aerobic count < 1000 CFU/g.
- Why compatibility with narasin/nicarbazin was rejected in 2023: in a trial with 6240 chickens (50 + 50 mg/kg) counts in caecal contents after heat treatment differed by < 0.5 log, but without it — 2.7 versus 3.5 log CFU/g, above the 0.5 log criterion. The applicant showed that DSM 32016 spores need a heat shock to germinate: in a new trial (84 samples, heating at 80 °C) after treatment 3.43 versus 3.52 log, without treatment 2.66 versus 3.31 log; colony identity was confirmed by a molecular profile (67 % of colonies from unheated samples and all from heated ones).
- In vitro test on the additive itself with three homogenisation methods: 9.51 log CFU/g after heat treatment versus 9.41 without — EFSA presents this as a 19 % increase in germination (in vivo — 23 %). EFSA notes that the new trial used 31 mg/kg narasin and 44 mg/kg nicarbazin, below the maximum authorised 50 + 50 mg/kg, and a two-component additive at 2 × 10⁸ CFU/kg. Amprolium: MIC > 500 mg/l, more than four times the maximum feed level (125 mg/l) — compatible.
- New list of coccidiostats in all parts of the annexes: halofuginone, diclazuril, monensin sodium, robenidine hydrochloride, salinomycin sodium, amprolium, monensin sodium with nicarbazin and narasin with nicarbazin — always in accordance with their own conditions of authorisation, since they are not authorised for every species in the annex. Doses unchanged: 1 × 10⁹ CFU/kg feed and 5 × 10⁸ CFU/l water; expiry dates 15 December 2030 (2020/1755) and 1 May 2034 (2024/1054). An OECD 406 test showed no skin sensitisation, but EFSA recalls that OECD guidelines are not validated for microorganisms — the additive is considered a sensitiser.