EU law sorts feed additives into 5 categories and 26 functional groups under Regulation (EC) No 1831/2003, while the US sorts them by legal route: food additive, GRAS substance, new animal drug in feed or AAFCO-defined ingredient. The 26 groups carry codes from 1a preservatives to 4e physiological condition stabilisers.
The category decides whether an authorisation names a holder (categories 4 and 5), which labelling rules apply, whether post-market monitoring is required and which establishment approval a feed business needs under Regulation (EC) No 183/2005. Each EU functional group below carries one entry with its act, and each EU category its usual US route.
Every value is compiled from EU acts, the EU Register, the eCFR and the Federal Register, checked on 3 November 2026; see the methodology.
How Are Feed Additives Classified?#
Feed additives are classified by principal function: each additive is allocated to one or more of the five categories of Article 6(1) and to a functional group of Annex I of Regulation (EC) No 1831/2003. Article 6(3) lets the Commission add categories or groups by comitology, and the functions themselves run from (a) to (g) in Article 5(3).
Under the EU feed additive regulation, which applies from 18 October 2004, one substance can sit in more than one group. Formic acid is listed as a preservative (1a) and as a silage additive (1k), with different limits, and Regulation (EC) No 767/2009 (Annex VI, point 8) requires the label to name the group of the principal function. Allocation, labelling and authorisation rules are set out in the EU feed additive regulation overview.
The Five EU Categories of Feed Additives#
The five EU categories of feed additives are technological, sensory, nutritional and zootechnical additives, plus coccidiostats and histomonostats, and only the first four are split into functional groups. The table below compares them by definition, groups and holder rule.
| Category (Art. 6(1)) | Definition | Functional groups | Holder-bound |
|---|---|---|---|
| (a) technological additives | "any substance added to feed for a technological purpose" | 15 (1a to 1o) | no (generic) |
| (b) sensory additives | "any substance, the addition of which to feed improves or changes the organoleptic properties of the feed, or the visual characteristics of the food derived from animals" | 2 (2a, 2b) | no (generic) |
| (c) nutritional additives | Art. 6(1)(c), no definition in the article | 4 (3a to 3d) | no (generic) |
| (d) zootechnical additives | "any additive used to affect favourably the performance of animals in good health or used to affect favourably the environment" | 5 (4a to 4e) | yes |
| (e) coccidiostats and histomonostats | Art. 6(1)(e) | none | yes |
Additives produced from genetically modified organisms are also holder-bound in every category (Article 9(6)).
Category 1: substances added for a technological purpose#
Category 1 covers "any substance added to feed for a technological purpose", in 15 functional groups from preservatives (1a) to other technological additives (1o). Category 1 authorisations are generic: the bacterial strain DSM 11798 (1m01), renewed by Implementing Regulation (EU) 2026/549, names pigs, poultry and ornamental birds, but no holder.
Category 2: substances that change taste, smell or colour#
Category 2 covers substances that improve or change the organoleptic properties of feed or the visual characteristics of food from animals, in two groups: colourants (2a) and flavouring compounds (2b). Colourants have three sub-groups, 2a(i) to 2a(iii); capsanthin 2a160c is a 2a(ii) entry. Flavouring compounds include sweeteners such as neohesperidin dihydrochalcone (NHDC) 2b959, and preservatives are never sensory additives.
Nutritional additives (category 3)#
Nutritional additives are category 3 of Regulation (EC) No 1831/2003: vitamins (3a), compounds of trace elements (3b), amino acids, their salts and analogues (3c) and urea and its derivatives (3d). Vitamins and trace elements carry legal maxima, not minima, where the act sets a limit. Feed amino acids stay in 3c; guanidinoacetic acid is the EU exception, filed as an other zootechnical additive (4d372, 4d32). The four groups have one example each.
- Vitamins (3a): beta-carotene 3a160, renewed by Implementing Regulation (EU) 2026/1148 of 28 May 2026.
- Trace elements (3b): sodium molybdate dihydrate 3b701, sheep only.
- Amino acids (3c): L-lysine, DL-methionine, L-threonine.
- Urea (3d): urea 3d1, ruminants with a functional rumen.
Zootechnical additives (category 4)#
Zootechnical additives are "any additive used to affect favourably the performance of animals in good health or used to affect favourably the environment", in five groups: digestibility enhancers (4a), gut flora stabilisers (4b), substances which favourably affect the environment (4c), other zootechnical additives (4d) and physiological condition stabilisers (4e). Phytase and xylanase are 4a, Bacillus strains and live yeast 4b and muramidase 4d16 is 4d.
The only 4c entry in the EU Register is 3-nitrooxypropanol (3-NOP) 4c1, for dairy cows and cows for reproduction (Implementing Regulation (EU) 2022/565). In the US, 3-NOP is an unapproved animal drug under FDA enforcement discretion (24 May 2024), and "zootechnical" is no US legal class. EU organic feed admits only enzymes and microorganisms from groups 4a to 4d, plus ammonium chloride (4d7, 4d8) for cats (Implementing Regulation (EU) 2021/1165).
Category 5: additives against coccidia and histomonads#
Category 5, coccidiostats and histomonostats, has no functional groups, every entry is holder-bound, and the EU Register lists no histomonostat. Its entries include monensin, diclazuril, nicarbazin and robenidine, and Article 5(4) bars every other antibiotic from authorisation. In the US, coccidiostats are new animal drugs in medicated feed under 21 CFR 558.
The 26 Functional Groups, with Letter Code and Example#
Annex I of Regulation (EC) No 1831/2003 sets 26 functional groups: 15 technological, 2 sensory, 4 nutritional and 5 zootechnical, and the group code opens the identification number of each entry, as in 1b320 or 4c1. The complete list below gives the Annex I wording, one EU entry and the page for each group.
| Code | Annex I wording | Example entry (EU ID, act, species, limit, end date) | Page |
|---|---|---|---|
| 1a | preservatives | formic acid, propionic acid, sorbic acid | feed preservatives |
| 1b | antioxidants | BHA 1b320, Impl. Reg. (EU) 2020/1399, all animal species other than cats, max 150 mg/kg complete feed (12 % moisture), to 2030-10-26 | feed antioxidants |
| 1c | emulsifiers | lecithins 1c322, Impl. Reg. (EU) 2017/1007, all animal species, to 2027-07-06 | feed emulsifiers |
| 1d | stabilisers | xanthan gum 1d415, Impl. Reg. (EU) 2026/538, to 2036-04-01 | technological hub (family table) |
| 1e | thickeners | methyl cellulose 1c461 (also listed in 1e), Impl. Reg. (EU) 2025/157, all species, no maximum | technological hub |
| 1f | gelling agents | celluloses 1c460i, 1c461, 1c464, 1c466 (also listed in 1f), Impl. Reg. (EU) 2025/157, to 2035-02-19 | technological hub |
| 1g | binders | lignosulphonate 1g565, Impl. Reg. (EU) 2024/749, max 10 000 mg/kg complete feed (weaned piglets, pigs for fattening, chickens for fattening, laying hens, cattle for fattening) or 8 000 mg/kg (other species), to 2034-03-21 | pellet binders |
| 1h | substances for control of radionucleide contamination | ferric (III) ammonium hexacyanoferrate (II), ruminants (domestic and wild), calves, lambs and kids prior to rumination, pigs (domestic and wild); no expiry date, Art. 10(2) re-evaluation noted in the register | technological hub |
| 1i | anticaking agents | sodium ferrocyanide 1i535 | anticaking agents |
| 1j | acidity regulators | potassium diformate 1j001, Impl. Reg. (EU) 2021/2092, weaned piglets and pigs for fattening, max 6 000 mg/kg, to 2031-12-20 | acidifiers hub |
| 1k | silage additives | homofermentative and Lactobacillus buchneri inoculants | silage additives |
| 1l | denaturants | no current entry (EU Register, 2026-11-03) | technological hub |
| 1m | substances for reduction of the contamination of feed by mycotoxins | bacterial strain DSM 11798 1m01, Impl. Reg. (EU) 2026/549, pigs, poultry, ornamental birds, min 1.7 x 10^8 CFU/kg complete feed (12 % moisture), 2026-04-05 to 2036-04-05 | mycotoxin binders hub |
| 1n | hygiene condition enhancers | 1n01 Bacillus subtilis CNCM I-4606, I-5043, I-4607 + Lactococcus lactis CNCM I-4609, Impl. Reg. (EU) 2024/764, feed with 60 to 90 % moisture | feed hygiene additives |
| 1o | other technological additives | 1o01 Bacillus subtilis KCCM 10673P + Aspergillus oryzae KCTC 10258BP, all animal species, 2020-03-01 to 2030-03-01 | technological hub |
| 2a | colourants: (i) substances that add or restore colour in feedingstuffs; (ii) substances which, when fed to animals, add colours to food of animal origin; (iii) substances which favourably affect the colour of ornamental fish or birds | 2a(ii): capsanthin 2a160c, Impl. Reg. (EU) 2020/1418, chickens for fattening, minor poultry for fattening, laying hens, minor poultry for laying, max 40 mg total carotenoids/kg complete feed, to 2030-10-27 | feed colourants |
| 2b | flavouring compounds | NHDC 2b959, Impl. Reg. (EU) 2026/1150, max 35 mg/kg complete feed (piglets, pigs for fattening, calves, sheep, food-producing and ornamental finfish, dogs), to 2036-06-18 | feed flavourings |
| 3a | vitamins, pro-vitamins and chemically well-defined substances having similar effect | beta-carotene 3a160, 3a160i, all animal species, Impl. Reg. (EU) 2026/1148 | vitamins hub |
| 3b | compounds of trace elements | sodium molybdate dihydrate 3b701, Impl. Reg. (EU) 2019/1965, sheep only, max 2.5 mg Mo/kg complete feed (12 % moisture), to 2029-12-18 | minerals hub |
| 3c | amino acids, their salts and analogues | L-lysine, DL-methionine, L-threonine | amino acids hub |
| 3d | urea and its derivatives | urea 3d1, Impl. Reg. (EU) 2023/1708, ruminants with a functional rumen | feed-grade urea |
| 4a | digestibility enhancers | phytase, xylanase | enzymes hub |
| 4b | gut flora stabilisers | Bacillus strains, live yeast | probiotics hub |
| 4c | substances which favourably affect the environment | 3-nitrooxypropanol 4c1, Impl. Reg. (EU) 2022/565, dairy cows and cows for reproduction, min 53, max 80 mg/kg complete feed (12 % moisture), to 2032-04-28 | 3-NOP (3-nitrooxypropanol) |
| 4d | other zootechnical additives | muramidase 4d16 (Novozymes A/S), Impl. Reg. (EU) 2019/805, chickens for fattening and minor poultry for fattening, min 25 000 LSU(F)/kg complete feed, to 2029-06-09; benzoic acid; bacteriophages 4d29 (Proteon Pharmaceuticals S.A.), poultry, 2025-08-05 to 2035-08-05 | several family pages |
| 4e | physiological condition stabilisers | 4e001 Bifidobacterium longum CNCM I-5642 (Nestlé Enterprises S.A., Division Nestlé Purina Petcare Europe), dogs; 4e2 molybdenum chelate of EDTA (Oligofeed SAS), honeybees | 4e section below |
Category 5 (coccidiostats and histomonostats) has no functional group. Limits in the table are EU legal minima or maxima per kg complete feed (12 % moisture) where the act says so.
Species and limits differ per entry, so the group alone never shows that a product may be fed to a given animal. Label terms such as "mycotoxin reducers" (Regulation (EC) No 767/2009, Annex VI) are abbreviations, not further groups. Single substances, from BHA to urea, appear in the A to Z index of feed additive substances.
Functional groups added since 2003#
Four functional groups were added after 2003: 1m by Commission Regulation (EC) No 386/2009 of 12 May 2009, 1n by Regulation (EU) 2015/2294 of 9 December 2015, and 1o and 4e by Regulation (EU) 2019/962 of 12 June 2019. The three newer category 1 groups read as follows.
- 1m (2009): "substances that can suppress or reduce the absorption, promote the excretion of mycotoxins or modify their mode of action".
- 1n (2015): "substances or, when applicable, microorganisms which favourably affect the hygienic characteristics of feed by reducing a specific microbiological contamination".
- 1o (2019): "substances or, when applicable, microorganisms added to feed for a technological purpose and which favourably affect the characteristics of the feed".
Physiological condition stabilisers (4e)#
Physiological condition stabilisers (4e) are additives that, fed to animals in good health, favourably affect their physiological condition, including resilience to stress factors, and the EU Register lists two entries. Both entries name a holder.
- 4e001 Bifidobacterium longum CNCM I-5642 (Nestlé Enterprises S.A.), dogs, Implementing Regulation (EU) 2025/1776, to 29 September 2035.
- 4e2 molybdenum chelate of EDTA (Oligofeed SAS), honeybees, Implementing Regulation (EU) 2026/2027, 1 October 2026 to 1 October 2036.
The group carries no health claim, and no EU feed additive holds a heat-stress authorisation.
One Page per Additive Family#
Each additive family below is matched with its EU home and its US route, from feed enzymes to rumen modifiers, with one hub page per row.
| # | Hub | EU home | US route |
|---|---|---|---|
| 1 | technological feed additives | category 1 (1a to 1i, 1k, 1l, 1n, 1o) | 21 CFR 582 GRAS and 21 CFR 573 |
| 2 | sensory feed additives | category 2 (2a, 2b) | carotenoids as color additives (21 CFR 73) |
| 3 | feed-grade amino acids | 3c (guanidinoacetic acid: 4d) | 21 CFR 582 GRAS and AAFCO definitions |
| 4 | vitamins in animal feed | 3a | 21 CFR 582 GRAS and AAFCO definitions |
| 5 | trace minerals in animal feed | 3b | 21 CFR 582 GRAS (trace-mineral salts, 582.80) |
| 6 | feed premixes | not a feed additive (Art. 2(2)(e)); carrier of 3a and 3b additives | n/a |
| 7 | feed enzymes | 4a (muramidase: 4d16) | AAFCO Table 30.1 and GRAS notices |
| 8 | probiotics for animals | 4b | AAFCO direct-fed microorganisms |
| 9 | prebiotics, yeast derivatives and postbiotics | yeast cell wall is a feed material, no EU additive entry | AAFCO definitions |
| 10 | feed acidifiers | 1a, 1j, 4d (potassium diformate 1a237a, 1j001, 4d800) | 21 CFR 582 GRAS and 21 CFR 573 |
| 11 | phytogenic feed additives | no legal category; botanicals sit in 2b (rosemary essential oil 2b406-eo, Impl. Reg. (EU) 2026/2113, all species) | product by product |
| 12 | mycotoxin binders and deactivators | 1m (1m01) | no mycotoxin claim in the US |
| 13 | coccidiostats | category 5 | 21 CFR 558 new animal drugs |
| 14 | antibiotic growth promoters | not authorisable (Art. 5(4)); last four deleted 2006-01-01 | 21 CFR 558 (for example avilamycin, 558.68, VFD drug) |
| 15 | methane-reducing feed additives | 4c (4c1) | 3-NOP under FDA enforcement discretion (2024-05-24) |
| 16 | rumen modifiers | mixed: urea 3d1; sodium bicarbonate is a feed material | urea: no section in 21 CFR 573, 582 or 584 |
How Does the US Classify Feed Additives?#
The US has no legal class called "feed additive": an additive reaches feed as a food additive (21 CFR 573), a GRAS substance (21 CFR 582 and 584 or an animal food GRAS notice), a new animal drug in feed (21 CFR 558) or an AAFCO-defined ingredient under FDA enforcement policy. The four routes compare as follows, with section counts from the eCFR structure of 1 October 2026.
| Route | Legal basis | Codified list | Example |
|---|---|---|---|
| Food additive | FD&C Act s. 409, petition under 21 CFR 571 | 21 CFR 573 (70 sections) | natamycin, 573.685 |
| GRAS | FD&C Act s. 201(s), listing or animal food GRAS notice | 21 CFR 582 (243 sections), 584 (3 sections) | trace-mineral salts, 582.80 |
| New animal drug in feed | NADA (21 CFR 514), medicated feed | 21 CFR 558 (63 sections; VFD in 558.6) | lubabegron, 558.330 |
| AAFCO-defined ingredient | state feed laws; FDA enforcement policy GFI #293; new ingredients via AFIC (GFI #294) | AAFCO Official Publication, chapter 6 | enzymes, Table 30.1 |
US feed additive regulation has changed since 2024. The AAFCO and FDA memorandum of understanding ended on 1 October 2024 and was not continued, so AAFCO-defined ingredients fall under FDA enforcement policy GFI #293 (notice of 24 October 2024), and new ingredients go through the Animal Food Ingredient Consultation, GFI #294 (notice of 7 January 2025). An FDA proposed rule on mandatory GRAS notification (11 August 2026, FR doc 2026-16296) is open for comment until 9 December 2026 and is not final. The Innovative FEED Act (H.R. 2203, S. 1906) would create "zootechnical animal food substances" but is not enacted. Petitions, GRAS notices and AFIC are explained under US feed additive regulation.
Lubabegron (21 CFR 558.330), natamycin for broiler feed at 11 ppm (21 CFR 573.685) and poloxalene (21 CFR 558.464) have no EU Register entry, and a US listing never implies EU status.
EU category and US route side by side#
EU nutritional additives map mostly to GRAS listings in 21 CFR 582 and AAFCO definitions, while EU coccidiostats and the former growth promoters map to new animal drugs in 21 CFR 558. The table below pairs each EU group with its usual US route.
| EU group | Usual US route |
|---|---|
| 3a, 3b, 3c | 21 CFR 582 GRAS and AAFCO definitions |
| 1a, 1b | 21 CFR 582 GRAS plus 21 CFR 573 (ethoxyquin, formic acid, sodium formate) |
| 4a | AAFCO Table 30.1 and GRAS notices |
| 4b | AAFCO direct-fed microorganisms |
| category 5 and former growth promoters | 21 CFR 558 new animal drugs |
| 2a carotenoids | 21 CFR 73 color additives |
EU limits are per kg complete feed (12 % moisture), US limits in g/ton, ppm or mg/head/day as printed, never converted here.
What Does Not Count as a Feed Additive?#
Premixtures, processing aids, feed materials, medicated feed and veterinary medicines are not feed additives under Regulation (EC) No 1831/2003. Article 2(2)(a) defines feed additives as substances, micro-organisms or preparations "other than feed material and premixtures" that are intentionally added "to feed or water" to perform a function of Article 5(3). What feed additives are and what they do is explained on the overview page. The five excluded types have these legal homes.
- Feed materials: Regulation (EU) No 68/2013; sodium bicarbonate and yeast cell wall are feed materials.
- Premixtures: excluded by Article 2(2)(e).
- Processing aids: outside the Regulation, Article 2(2)(h).
- Medicated feed: Regulation (EU) 2019/4.
- Veterinary medicinal products: Regulation (EU) 2019/6.
Withdrawn and Denied Feed Additives#
Withdrawn or superseded entries move to Annex II of the EU Register, often with transitional measures, and the best-known withdrawal is that of the antibiotic growth promoters, allowed only until 31 December 2005 and deleted from 1 January 2006 under Article 11(2) of Regulation (EC) No 1831/2003. A denial refuses the authorisation outright, as Implementing Regulation (EU) 2022/1375 did for ethoxyquin. The table sets four cases next to their US status.
| Additive | EU act and date | EU wording | US status |
|---|---|---|---|
| monensin sodium, salinomycin sodium, avilamycin, flavophospholipol as growth promoters | Regulation (EC) No 1831/2003, Art. 11(2) | marketed until 2005-12-31, deleted 2006-01-01 (monensin and salinomycin remain coccidiostats) | 21 CFR 558 new animal drugs (avilamycin: 558.68, VFD) |
| ethoxyquin (E 324) | Impl. Reg. (EU) 2022/1375, in force 2022-08-28 (suspended from 2017-06-28 by Impl. Reg. (EU) 2017/962) | authorisation denied | food additive, 21 CFR 573.380, 150 ppm |
| formaldehyde | Impl. Reg. (EU) 2018/183 | authorisation denied | food additive, 21 CFR 573.460 |
| sodium saccharin E 954(iii) | Impl. Reg. (EU) 2024/1727; transitional periods ended 2026-07-11 | withdrawn from the market | not shown |
An EU denial does not remove a US listing: ethoxyquin and formaldehyde both keep their 21 CFR 573 sections.
Regulation Summary: Authorisation Period, Holders and Renewal#
An EU feed additive authorisation runs for 10 years and is renewable for further 10-year periods, while Great Britain has issued authorisations without an end date since 1 April 2025. A renewal application is due at the latest one year before expiry (Article 14(1) of Regulation (EC) No 1831/2003). Every current entry is listed in the EU Register of Feed Additives, with its identification number, act and expiry. The GB rule (SI 2025/361, regulation 23(3)) excepts urgent provisional authorisations.
Holder status follows the category (Article 9(6)). An EU application costs EUR 1.1 million on average, from EUR 50,000 to EUR 3.4 million by dossier type, according to Commission staff working document SWD(2024) 46. Implementing Regulation (EU) 2026/1115 of 26 May 2026 replaces the target-animal categories from 16 December 2026.
How to Choose the Right Type of Additive#
Choose a feed additive type in four checks, from the production goal to the dose basis written in the act.
- Map the goal to a category: feed quality 1, taste or colour 2, nutrient supply 3, performance or environment 4, coccidiosis control 5.
- Confirm an entry covers species and market: EU identification number and act, or US section or route.
- Check form and stability in premix and pellet.
- Read the dose basis: EU per kg complete feed (12 % moisture), US g/ton, ppm or mg/head/day.
Entries name their animals one by one, so step 2 decides most choices of feed additives by species; programmes by animal are grouped under feed additives by species.
Questions About Feed Additive Types#
Three questions about feed additive types come from the search results themselves.
Are there four or five types of feed additives?#
Five: Article 6(1) of Regulation (EC) No 1831/2003 sets five categories, and lists that name four leave out coccidiostats and histomonostats.
Which types of feed additives are used in poultry?#
Poultry feed draws on all five categories, including enzymes (4a), gut flora stabilisers (4b), amino acids (3c), vitamins (3a), trace elements (3b), colourants (2a) and coccidiostats (category 5). Each EU entry names its bird categories. The programme by phase is set out under poultry feed additives.
Are phytogenics and eubiotics a legal category?#
No: phytogenics, eubiotics and probiotics are market terms without legal status; each product sits in the group its authorisation names, for example a botanical flavouring in 2b or a Bacillus strain in 4b. Rosemary essential oil, for instance, holds the entry 2b406-eo (Implementing Regulation (EU) 2026/2113).