Safety and efficacy of a feed additive consisting of l‐tryptophan produced with Escherichia coli CCTCC M 2024517 for all animal species (Anhui Huaheng Biotechnology Co., Ltd.)
Roberto Edoardo Villa, Giovanna Azimonti, Eleftherios Bonos, Henrik Christensen, Mojca Durjava, Birgit Dusemund, Ronette Gehring, Boet Glandorf, Maryline Kouba, Marta López‐Alonso, Francesca Marcon, Carlo Nebbia, Alena Pechová, Miguel Prieto‐Maradona, Ilen Röhe
TL;DR
This paper evaluates the safety and effectiveness of l-tryptophan produced using a genetically modified E. coli strain for use in animal feed and drinking water.
Contribution
The study confirms the safety of l-tryptophan produced with E. coli CCTCC M 2024517 for animal nutrition and identifies efficacy differences between ruminant and non-ruminant species.
Findings
The l-tryptophan additive is safe for all animal species when used appropriately in feed.
The additive is effective for non-ruminants but needs protection from ruminal degradation to be effective in ruminants.
No safety concerns were found for consumers or the environment.
Abstract
Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of l‐tryptophan produced with a genetically modified strain of Escherichia coli (CCTCC M 2024517) as a nutritional additive in feed and water for drinking for all animal species and categories. The l‐tryptophan produced by fermentation with E. coli CCTCC M 2024517 did not give rise to any safety concern regarding the genetic modifications of the production strain. No viable cells nor DNA of the production strain was detected in the final product. The use of l‐tryptophan produced with E. coli CCTCC M 2024517 in feed is safe for the target species when supplemented in appropriate amounts to the diet according to their nutritional needs. The FEEDAP Panel had concerns on the use of l‐tryptophan in water for drinking. The use of l‐tryptophan produced by fermentation…
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FIGURE 1| Parameter | Specification | Analysis | ||
|---|---|---|---|---|
| Average | Range | # batches | ||
|
| ||||
|
| ≥ 98.0 | 100.9 | 100.3–101.5 | 5 |
| Loss on drying (%) | ≤ 1 | 0.18 | 0–0.3 | 5 |
| Specific optical rotation (°) | −33.0 to −30.0 | −32.4 | −32.2 to −32.6 | 5 |
|
| ||||
| Lead (mg/kg) | 0.027–0.029 | 3 | ||
| Mercury (mg/kg) | < 0.002 | 3 | ||
| Cadmium (mg/kg) | 0.0031–0.0035 | 3 | ||
| Arsenic (mg/kg) | < 0.01 | 3 | ||
| EBT (mg/kg) | < 10 | 3 | ||
| MTCA (mg/kg) | 0.6–0.7 | 3 | ||
| Dioxins and furans (upper bound) | ||||
| PCDD/Fs (ng WHO2005‐TEQ/kg) | 0.14 | 3 | ||
| PCDD/Fs + PCBs (ng WHO2005‐TEQ/kg) | 0.269 | 3 | ||
| nDL‐PCBs (μg/kg) | 3.0 | 3 | ||
| Mycotoxins | ||||
| Aflatoxins (unspecified) (μg/kg) | < 0.05–0.2 | 3 | ||
| Fumonisins B1 + B2 + B3 (μg/kg) | < 25.0 | 3 | ||
| Ochratoxin A (μg/kg) | < 2.8 | 3 | ||
| Deoxynivalenol (μg/kg) | < 134–198.3 | 3 | ||
| Zearalenone (μg/kg) | < 17 | 3 | ||
| Citrinin (μg/kg) | < 15 | 3 | ||
|
| ||||
|
| Not detected | 3 | ||
|
| Not detected | 3 | ||
| Yeast (per 1 g sample) | Not detected | 3 | ||
| Moulds (per 1 g sample) | Not detected | 3 | ||
|
| Not detected | 3 | ||
| Endotoxin activity (IU/mg) | < 3 | 3 | ||
|
| ||||
| Physical form | Solid | |||
| Density (reported, g/mL) | 0.25–0.45 | |||
| Solubility (reported, g/L at 25°C) | 11.4 | |||
| Dusting potential (Stauber Heubach) (mg/m3) | 1904–2115 | 3 | ||
|
| ||||
| RT, 6 months | 1–2.5 | 3 | ||
|
| ||||
| Vitamin–mineral premix, RT, 3 months | 0–14.3 | 3 | ||
|
| ||||
| Piglet diet, mash, RT, 3 months | 0 | 3 | ||
| Piglet diet, pellet, RT, 3 months | 0–5.1 | 3 | ||
|
| ||||
| 20°C, 48 h | 0–5.3 | 3 | ||
|
(coefficient of variation of 10 subsamples, %) | ||||
| Pelleted feed (free tryptophan) | 3.8 | 1 | ||
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Taxonomy
TopicsAgricultural safety and regulations · Genetically Modified Organisms Research · Pesticide Residue Analysis and Safety
INTRODUCTION
1
Background and Terms of Reference
1.1
Regulation (EC) No 1831/20031 establishes the rules governing the Community authorisation of additives for use in animal nutrition. In particular, Article 4(1) of that Regulation lays down that any person seeking authorisation for a feed additive or for a new use of feed additive shall submit an application in accordance with Article 7.
The European Commission received a request from Anhui Huaheng Biotechnology Co., Ltd.2 (represented in EU by Kempex Holland B.V.) for the authorisation of the additive consisting of L‐tryptophan produced with Escherichia coli CCTCC M 2024517, when used as a feed additive for all animal species (category: nutritional additives; functional group: amino acids, their salts and analogues).
According to Article 7(1) of Regulation (EC) No 1831/2003, the Commission forwarded the application to the European Food Safety Authority (EFSA) as an application under Article 4(1) (authorisation of a feed additive or new use of a feed additive). The dossier was received on 8 January 2025 and the general information and supporting documentation are available at https://open.efsa.europa.eu/questions/EFSA‐Q‐2025‐00009. The particulars and documents in support of the application were considered valid by EFSA as of 27 March 2025.
According to Article 8 of Regulation (EC) No 1831/2003, EFSA, after verifying the particulars and documents submitted by the applicant, shall undertake an assessment in order to determine whether the feed additive complies with the conditions laid down in Article 5. EFSA shall deliver an opinion on the safety for the target animals, consumer, user and the environment and on the efficacy of the feed additive consisting of l‐tryptophan produced with E. coli CCTCC M 2024517 when used under the proposed conditions of use (see Section 3.1.4).
Additional information
1.2
The additive l‐tryptophan produced with E. coli CCTCC M 2024517 has not been previously authorised as a feed additive in the European Union. l‐tryptophan produced by fermentation with different production strains is currently authorised for its use in all animal species as a nutritional additive.3
The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) issued a series of scientific opinions on the safety and efficacy of l‐tryptophan produced by fermentation with different strains of E. coli, when used as an amino acid in feed.4
DATA AND METHODOLOGIES
2
Data
2.1
The present assessment is based on data submitted by the applicant in the form of a technical dossier5 in support of the authorisation request for the use of l‐tryptophan produced with Escherichia coli CCTCC M 2024517 as a feed additive.
In accordance with Article 38 of the Regulation (EC) No 178/20026 and taking into account the protection of confidential information and of personal data in accordance with Articles 39 to 39e of the same Regulation, and of the Decision of EFSA's Executive Director laying down practical arrangements concerning transparency and confidentiality,7 a non‐confidential version of the dossier has been published on Open.EFSA.
According to Article 32c(2) of Regulation (EC) No 178/2002 and to the Decision of EFSA's Executive Director laying down the practical arrangements on pre‐submission phase and public consultations, EFSA carried out a public consultation on the non‐confidential version of the technical dossier from 9 July to 30 July 2025, for which no comments were received.
The confidential version of the technical dossier was subject to a target consultation of the interested Member States from 1 April to 1 July 2025, for which the received comments were considered for the assessment.
The FEEDAP Panel used the data provided by the applicant together with data from other sources, such as previous risk assessments by EFSA or other expert bodies, peer‐reviewed scientific papers, other scientific reports and experts' knowledge, to deliver the present output.
EFSA has verified the European Union Reference Laboratory (EURL) report as it relates to the methods used for the control of l‐tryptophan in animal feed.8
Methodologies
2.2
The approach followed by the FEEDAP Panel to assess the safety and efficacy of l‐tryptophan is in line with the principles laid down in Regulation (EC) No 429/20089 and the relevant guidance documents: Guidance on the assessment of the safety of feed additives for the consumer (EFSA FEEDAP Panel, 2017a); Guidance on the identity, characterisation and conditions of use of feed additives (EFSA FEEDAP Panel, 2017b); Guidance on the assessment of the safety of feed additives for the target species (EFSA FEEDAP Panel, 2017c); Guidance on the characterisation of microorganisms used as feed additives or as production organisms (EFSA FEEDAP Panel, 2018); Guidance on the assessment of the safety of feed additives for the environment (EFSA FEEDAP Panel, 2019); Guidance on the assessment of the safety of feed additives for the users (EFSA FEEDAP Panel, 2023); Guidance on the assessment of the efficacy of feed additives (EFSA FEEDAP Panel, 2024); and EFSA statement on the requirements for whole genome sequence analysis of microorganisms intentionally used in the food chain (EFSA, 2024).
ASSESSMENT
3
l‐Tryptophan (≥ 98% on a dry matter [DM] basis), produced by fermentation with a genetically modified strain of E. coli (CCTCC M 2024517), is intended to be used as a nutritional additive (functional group: amino acids, their salts and analogues) in feed and water for drinking for all animal species and categories.
Characterisation
3.1
Characterisation of the production microorganism
3.1.1
l‐Tryptophan is produced with a genetically modified derivative of E. coli K‐12, which is deposited in the China Centre for Type Culture Collection (CCTCC) with accession number CCTCC M 2024517.10
The taxonomic identification of the production strain CCTCC M 2024517 as E. coli K‐12 derivative was confirmed ■■■■■ based on the whole genome sequencing (WGS) data.11 ■■■■■.
E. coli K‐12 is well characterised, its safety (non‐pathogenicity) has been documented (Gorbach, 1978; Kaper et al., 2004) and its ineffectiveness in colonising the human gut has been reported (Smith, 1975).
The antimicrobial susceptibility of the production strain was tested using a broth microdilution method against the battery of antibiotics recommended by the EFSA FEEDAP Panel (EFSA FEEDAP Panel, 2018).12 All the minimum inhibitory concentration (MIC) values fell below the corresponding cut‐off values for ‘Enterobacteriaceae’, ■■■■■. Therefore, the production strain is considered susceptible to all relevant antibiotics.
■■■■■.13 ■■■■■ Therefore, the FEEDAP Panel concludes that the strain harbours no acquired AMR genes and raises no safety concerns.
■■■■■.14 ■■■■■ therefore, considered of no concern.
Characterisation of the parental or recipient microorganism and genetic modification description
3.1.1.1
■■■■■.15
■■■■■
■■■■■:16
- ■■■■■
- ■■■■■
■■■■■ (see Section 3.1.1).
■■■■■.17 No concerns were identified.
Manufacturing process
3.1.2
l‐Tryptophan is produced by fermentation with E. coli CCTCC M 2024517.18 ■■■■■.
The applicant stated that no antimicrobial substances are used in the manufacturing process.19
Characterisation of the additive
3.1.3
l‐Tryptophan (International Union of Pure and Applied Chemistry (IUPAC) name: (2S)‐2‐amino‐3‐(1H‐indol‐3‐yl) propanoic acid) is a compound identified by Chemical Abstracts Service (CAS) No 73‐22‐3 and European Inventory of Existing Commercial Chemical Substances (EINECS) No 200‐795‐6. It has a molecular weight of 204.23 g/mol; the molecular formula is C_11_H_12_N_2_O_2_ and its structural formula is given in Figure 1.
Structural formula of l‐tryptophan.
The additive is specified to contain ≥ 98% l‐tryptophan on DM basis and ≤ 1% water.
The data provided by the applicant on the batch‐to‐batch variation,20 impurities21 and physical properties22 of the additive are reported in Table 1.
The data provided showed compliance with the specifications set by the applicant. The FEEDAP Panel considers that the microbial contamination and the impurities detected are of no safety concern.
The total amount of identified material in DM basis was 100%, all corresponding to tryptophan.
The presence of viable cells of the production strain was investigated in three batches of the additive, tested in triplicate.23 ■■■■■. No viable cells were detected in any of the tested samples.
The presence of DNA from the production strain was investigated in three batches of the additive.24 ■■■■■ by polymerase chain reaction. ■■■■■. The limit of detection (LOD) of samples spiked with genomic DNA of the production strain was 1 ng/g of additive. No DNA from the production strain was detected in any of the samples.
Conditions of use
3.1.4
l‐Tryptophan is intended to be used in complete feed for all animal species, directly or through complementary feed, premixtures or water. No inclusion levels have been proposed as the requirements, in quantitative terms, depend on the species, the age of the animal, the physiological state of the animal, the performance level, the environmental conditions and the amino acid composition of the unsupplemented diet.
Safety
3.2
Safety of the production microorganism
3.2.1
The parental strain of E. coli CCTCC M 2024517 is considered to be safe. The genetic modifications performed to obtain the production strain E. coli CCTCC M 2024517 have the purpose to increase the production of l‐tryptophan. The taxonomic identification of the production strain was unequivocally established, it does not carry acquired AMR genes and the genetic modifications do not raise safety concerns. No viable cells nor DNA of the production strain were detected in the final product. Therefore, the additive does not raise any safety concern regarding the production strain.
Safety for the target species, consumers and the environment
3.2.2
The l‐tryptophan requirements of the target animal species and the safety of this essential amino acid in non‐ruminant and ruminant nutrition are well known to feed formulators and available in general publications on animal nutrition.
Safety concerns on the use of the additive may derive from the amino acid itself, l‐tryptophan and/or on the residues/metabolites derived from the fermentation process.
The additive is produced by fermentation with a genetically modified strain of E. coli (CCTCC M 2024517), and no safety concerns were identified for the production strain (see Section 3.2.1), the fermentation process and its residues/metabolites. Moreover, the resulting product is highly purified (≥ 98.0% l‐tryptophan and 100% identified material on a DM basis). The FEEDAP Panel reiterates that ruminal metabolism of unprotected l‐tryptophan may result in the production of toxic quantities of 3‐methylindole (skatole), which causes pulmonary disease (fog fever; acute bovine pulmonary emphysema) in cattle and goats (Hammond et al., 1979). Consequently, only a rumen‐protected form of l‐tryptophan should be used in ruminants. l‐Tryptophan produced with E. coli CCTCC M 2024517 is safe for non‐ruminant species when used to supplement the diet in appropriate amounts to satisfy the animal requirements. However, the FEEDAP Panel reiterates its statement on the safety of the use of amino acids in water for drinking (EFSA FEEDAP Panel, 2010), for hygienic reasons and for the risk of nutritional imbalances when amino acids are administered simultaneously in feed and in water for drinking.
No endotoxin activity was found in the final additive. Considering the LOD of 3000 IU/g, the maximum possible content would still be far below the levels commonly found in feedingstuffs (up to 1,000,000 IU/g) (Cort et al., 1990).
The absorption and metabolic fate of l‐tryptophan in the animals is well known. Once absorbed, the amino acid l‐tryptophan, supplemented to feed, will be incorporated into proteins of tissues and/or products of animal origin and any of its potential excess will be metabolised and excreted. Therefore, the protein composition of tissues and products of animal origin will not be affected using l‐tryptophan in animal nutrition. 1,1′‐Ethylidene‐bis‐l‐tryptophan (EBT) and 1‐methyl‐1,2,3,4‐tetrahydro‐beta‐carboline‐3‐carboxylic acid (MTCA) present in a specific brand of l‐tryptophan produced by fermentation were implicated in the eosinophilia–myalgia syndrome outbreak that occurred in humans in New Mexico in 1989 (Hertzman et al., 1990). The analysed concentrations of EBT in l‐tryptophan produced by fermentation with E. coli CCTCC M 2024517 were shown to be < 10 mg/kg additive and those of MTCA < 1 mg/kg (see Section 3.1.3). Therefore, the Panel considers that the use of the additive in animal species is safe for the consumer.
The amino acid l‐tryptophan is a physiological and natural component of animals and plants. When consumed, it will be absorbed, and the non‐absorbed fraction will be incorporated into the intestinal microbial mass and excreted as such. The use of amino acids in water for drinking, when given in addition to complete diets with a well‐balanced amino acid profile, would disturb the nitrogen balance and increase nitrogen excretion via urine. The use of the product l‐tryptophan in animal nutrition would not lead to any localised increase in the concentration in the environment. It is concluded that the use of the product, l‐tryptophan produced by fermentation with E. coli CCTCC M 2024517 as a feed additive does not represent a risk to the environment.
Safety for the user
3.2.3
Based on the highest dusting potential measured value (see Section 3.1.3), the FEEDAP Panel considers that the exposure of users through inhalation is likely.
No specific information was submitted.25 In the absence of data, the FEEDAP Panel is not in the position to conclude on the potential of the additive to be an irritant to skin or eyes, or on its potential to be a dermal sensitiser.
Users can suffer from occupational respiratory disease depending on the level of endotoxins in air and dust (Rylander, 1999; Thorn & Kerekes, 2001). Although no occupational exposure limits have been set in the EU for inhalable endotoxins, the Dutch Expert Committee on Occupational Safety recommended a health‐based occupational exposure limit for inhalable endotoxins of 90 IU/m^3^ (8‐hour time‐weighted average) (DECOS, 2010). To reduce the risk, the FEEDAP Panel considers that the exposure of the users to bacterial endotoxins potentially present in the additive should be minimised.
Conclusions on the safety for the user
3.2.3.1
In the absence of information, it is not possible to conclude on the potential of the additive to be irritant to skin and/or eyes or to be a skin sensitiser.
Efficacy
3.3
Efficacy studies are not required for amino acids that occur naturally in plant and animal proteins. The nutritional role of the amino acid l‐tryptophan is well established in the scientific literature. The additive l‐tryptophan is regarded as an efficacious source of the essential amino acid l‐tryptophan for non‐ruminant nutrition. For the supplemental l‐tryptophan to be as efficacious in ruminants as in non‐ruminant species, it would require protection against degradation in the rumen.
Post‐market monitoring
3.4
The FEEDAP Panel considers that there is no need for specific requirements for a post‐market monitoring plan other than those established in the Feed Hygiene Regulation26 and Good Manufacturing Practice.
CONCLUSIONS
4
The production strain E. coli CCTCC M 2024517 does not raise safety concerns regarding the genetic modifications. No viable cells nor DNA of the production strain are detected in the final product. Therefore, the FEEDAP Panel concludes that the additive does not pose any safety concern regarding the production strain.
The use of l‐tryptophan produced with E. coli CCTCC M 2024517 to supplement feed to compensate for tryptophan deficiency in feedingstuffs is safe for non‐ruminant species. There may be a risk for an increased production of toxic metabolites when unprotected tryptophan is used in ruminants. The FEEDAP Panel has concerns on the use of l‐tryptophan in water for drinking.
The use of l‐tryptophan produced by fermentation with E. coli CCTCC M 2024517 in animal nutrition is considered safe for the consumers and for the environment.
Regarding user safety, the FEEDAP Panel cannot conclude on the potential of the additive to be an irritant to skin or eyes, or on its potential to be a dermal sensitiser.
The feed additive consisting of l‐tryptophan produced by fermentation with E. coli CCTCC M 2024517 is regarded as an effective source of the amino acid l‐tryptophan for all non‐ruminant species. In order to be as efficacious in ruminants as in non‐ruminants, it should be protected from ruminal degradation.
ABBREVIATIONSCASChemical Abstracts ServiceCFUcolony‐forming unitCVcoefficient of variationDMdry matterEBT1,1′‐ethylidene‐bis‐l‐tryptophanEINECSEuropean Inventory of Existing Chemical SubstancesEURLEuropean Union Reference LaboratoryFEEDAPEFSA Scientific Panel on Additives and Products or Substances used in Animal FeedIUInternational units for endotoxin activityIUPACInternational Union of Pure and Applied ChemistryLODlimit of detectionLOQlimit of quantificationMICminimum inhibitory concentrationMTCA1‐methyl‐1,2,3,4‐tetrahydro‐beta‐carboline‐3‐carboxylic acidPCBspolychlorinated biphenylsPCDDsPolychlorinated dibenzo‐p‐dioxinsPCDFspolychlorinated dibenzofuransWGSWhole genome sequencing
REQUESTOR
European Commission
QUESTION NUMBER
EFSA‐Q‐2025‐00009
COPYRIGHT FOR NON‐EFSA CONTENT
EFSA may include images or other content for which it does not hold copyright. In such cases, EFSA indicates the copyright holder and users should seek permission to reproduce the content from the original source.
PANEL MEMBERS
Roberto Edoardo Villa, Giovanna Azimonti, Eleftherios Bonos, Henrik Christensen, Mojca Durjava, Birgit Dusemund, Ronette Gehring, Boet Glandorf, Maryline Kouba, Marta López‐Alonso, Francesca Marcon, Carlo Nebbia, Alena Pechová, Miguel Prieto‐Maradona, Ilen Röhe, and Katerina Theodoridou.
LEGAL NOTICE
Relevant information or parts of this scientific output have been blackened in accordance with the confidentiality requests formulated by the applicant pending a decision thereon by EFSA. The full output has been shared with the European Commission, EU Member States (if applicable) and the applicant. The blackening may be subject to review once the decision on the confidentiality requests is adopted by EFSA and in case it rejects some of the confidentiality requests.
The reference list from the paper itself. Each links out to its DOI / PubMed record.
- 1Cort, N. , Fredriksson, G. , Kindahl, H. , Edqvist, L. E. , & Rylander, R. (1990). A clinical and endocrine study on the effect of orally administered bacterial endotoxin in adult pigs and goats. Journal of Veterinary Medicine Series A, 37, 130–137.2113750 10.1111/j.1439-0442.1990.tb 00884.x · doi ↗ · pubmed ↗
- 2DECOS (Dutch Expert Committee on Occupational Safety) . (2010). Endotoxins: health based recommended exposure limit. A report of the Health Council of the Netherlands, publication no. 2010/04OSH. The Hague, the Netherlands: Health Council of the Netherlands.
- 3EFSA BIOHAZ Panel (EFSA Panel on Biological Hazards) , Koutsoumanis, K. , Allende, A. , Alvarez‐Ordóñez, A. , Bolton, D. , Bover‐Cid, S. , Chemaly, M. , De Cesare, A. , Hilbert, F. , Lindqvist, R. , Nauta, M. , Nonno, R. , Peixe, L. , Ru, G. , Simmons, M. , Skandamis, P. , Suffredini, E. , Cocconcelli, P. S. , Suarez, J. E. , & Herman, L. (2023). Statement on how to interpret the QPS qualification on ‘acquired antimicrobial resistance genes’. EFSA Journal, 21(10), 1–13. 10.29 · doi ↗ · pubmed ↗
- 4EFSA (European Food Safety Authority) . (2024). EFSA statement on the requirements for whole genome sequence analysis of microorganisms intentionally used in the food chain. EFSA Journal, 22(8), 8912. 10.2903/j.efsa.2024.8912 PMC 1131780639135845 · doi ↗ · pubmed ↗
- 5EFSA FEEDAP Panel (EFSA Panel on Additives and Products or Substances Used in Animal Feed) . (2010). Scientific Opinion on the use of feed additives authorised/applied for use in feed when supplied via water. EFSA Journal, 8(12), 1956. 10.2903/j.efsa.2010.1956 · doi ↗
- 6EFSA FEEDAP Panel (EFSA Panel on Additives and Products or Substances used in Animal Feed) , Bampidis, V. , Azimonti, G. , Bastos, M. D. L. , Christensen, H. , Durjava, M. , Dusemund, B. , Kouba, M. , López‐Alonso, M. , López Puente, S. , Marcon, F. , Mayo, B. , Pechová, A. , Petkova, M. , Ramos, F. , Villa, R. E. , Woutersen, R. , Brantom, P. , … Galobart, J. (2023). Guidance on the assessment of the safety of feed additives for the users. EFSA Journal, 21(12), 8469. 10.2903/ · doi ↗ · pubmed ↗
- 7EFSA FEEDAP Panel (EFSA Panel on Additives and Products or Substances used in Animal Feed) , Bampidis, V. , Azimonti, G. , Bastos, M. L. , Christensen, H. , Durjava, M. , Dusemund, B. , Kouba, M. , López‐Alonso, M. , López Puente, S. , Marcon, F. , Mayo, B. , Pechová, A. , Petkova, M. , Ramos, F. , Villa, R. E. , Woutersen, R. , Dierick, N. , Gropp, J. , … Ortuño, J. (2024). Guidance on the assessment of the efficacy of feed additives. EFSA Journal, 22(7), 8856. 10.2903/j.efs · doi ↗ · pubmed ↗
- 8EFSA FEEDAP Panel (EFSA Panel on Additives and Products or Substances used in Animal Feed) , Bampidis, V. , Bastos, M. , Christensen, H. , Dusemund, B. , Kouba, M. , Kos Durjava, M. , López‐Alonso, M. , López Puente, S. , Marcon, F. , Mayo, B. , Pechová, A. , Petkova, M. , Ramos, F. , Sanz, Y. , Villa, R. E. , Woutersen, R. , Brock, T. , … Azimonti, G. (2019). Guidance on the assessment of the safety of feed additives for the environment. EFSA Journal, 17(4), 5648. 10.2903/j.e · doi ↗ · pubmed ↗