Efficacy of sodium formate as a technological feed additive (preservative) for all animal species

Abstract

In 2015, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP ) issued an opinion on the safety and efficacy of ammonium, calcium and sodium formate when used as a technological additive (preservative) for all animal species. Sodium formate was considered safe for all animal species at a maximum concentration of 10,000 mg formic acid equivalents/kg complete feed (with the exception of pigs, for which a maximum concentration of 12,000 mg formic acid equivalents/kg complete feed was considered safe). Sodium formate was also considered safe for the consumer and the environment. The Panel also concluded that sodium formate is non‐irritant to the skin, but mildly irritant to the eyes, and is a respiratory irritant with a potential for sensitisation. The Panel also concluded that ‘Sodium formate or solid sodium formate had no discernible effects on microbial numbers in the feed materials examined. The preservative effect of the three formate salts in water for drinking was not demonstrated’. In the current opinion, additional data to demonstrate the efficacy of sodium formate as a preservative in feed for all animal species were assessed. The Panel concluded that sodium formate has the potential to be efficacious as a preservative in feedingstuffs for all animal species at the proposed use level. In the absence of data, the Panel cannot conclude on the efficacy of the use of the additive in water for drinking.

1 Introduction

1.1 Background and Terms of Reference as provided by the requestor

Regulation (EC) No 1831/2003 establishes rules governing the Community authorisation of additives for animal nutrition and, in particular, Article 9 defines the terms of the authorisation by the Commission.

The applicant, FEFANA ASBL, is seeking a Community authorisation for sodium formate (E237) as a feed additive to be used as a preservative for all animal species (Table 1).

Table 1. Description of the substances

Category of additive	Technological additives
Functional group of additive	Preservative
Description	Sodium formate (E237)
Target animal category	All animal species
Applicant	FEFANA ASBL
Type of request	New opinion

On 11 March 2015, the Panel on Additives and Products or Substances used in Animal Feed of the European Food Safety Authority (“Authority”), in its opinion on the safety and efficacy of the product, could not conclude on the efficacy of sodium formate (E237), calcium formate (E238) and ammonium formate (E295) as preservative for compound feed or feed materials. After the discussion with the Member States at the Standing Committee, it was suggested to check for the possibility to demonstrate the efficacy.

The Commission (EC) gave the possibility to the applicant to submit complementary information in order to complete the assessment and to allow a revision of the Authority's opinion. The new data have been received on 28 February 2020.

In view of the above, the Commission asks the Authority to deliver a new opinion on sodium formate (E 237) as a feed additive for all animal species based on the additional data submitted by the applicant.

1.2 Additional information

Sodium formate (E 237) is currently listed in the EU Register of Feed Additives as a technological additive (functional group: preservative) for use in feed for all animal species.11 Commission Directive of 8 July 1985 amending the Annexes to Council Directive 70/524/EEC concerning additives in feedingstuffs.
The re‐evaluation of sodium formate as technological additive (functional group: preservative) for use in feed for all animal species is the subject of the current application.

The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) delivered in 2015 and opinion on the safety and efficacy of ammonium, calcium and sodium formate when used as a technological additive (preservative) for all animal species (EFSA FEEDAP Panel, 2015). In that opinion, the FEEDAP Panel concluded that ‘Sodium formate or solid sodium formate had no discernible effects on microbial numbers in the feed materials examined. The preservative effect of the three formate salts in water for drinking was not demonstrated’. The applicant has now submitted additional data to demonstrate the efficacy of sodium formate as a preservative in feed for all animal species.

2 Data and methodologies

2.1 Data

The present assessment is based on the data submitted by the applicant in the form of additional information22 Dossier reference: FAD‐2020‐0021.
following a previous application on the same product.33 Dossier reference: FAD‐2010‐0312.

2.2 Methodologies

The approach followed by the FEEDAP Panel to assess the efficacy of sodium formate is in line with the principles laid down in Regulation (EC) No 429/200844 Commission Regulation (EC) No 429/2008 of 25 April 2008 on detailed rules for the implementation of Regulation (EC) No 1831/2003 of the European Parliament and of the Council as regards the preparation and the presentation of applications and the assessment and the authorisation of feed additives. OJ L 133, 22.5.2008, p. 1.
and the relevant guidance documents: Guidance on the assessment of the efficacy of feed additives (EFSA FEEDAP Panel, 2018).

3 Assessment

The additive under assessment is solid sodium formate. The additive is intended to be used as a technological additive, functional group preservative in feedingstuffs and water for drinking for all animal species. The proposed maximum levels in feed are of 12,000 mg/kg complete feed for pigs and a 10,000 mg/kg feed for all the other species, all expressed as formic acid equivalents/kg complete feed. The corresponding maximum content in water for drinking is 4,000 mg/L for all animal species, with the exception of ruminants, for which a maximum content is not proposed. No minimum level is proposed.

The additive was fully characterised in the previous opinion on ‘the safety and efficacy of ammonium, calcium and sodium formate when used as a technological additive for all animal species’ (EFSA FEEDAP Panel, 2015). Sodium formate was considered safe for all animal species at a maximum level of 10,000 mg formic acid equivalents/kg complete feed, with the exception of pigs, for which a maximum level of 12,000 mg formic acid equivalents/kg complete feed was considered safe. Sodium formate was also considered safe for the consumer and the environment. The Panel also concluded that sodium formate is non‐irritant to the skin, but mildly irritant to the eyes, and is a respiratory irritant with a potential for sensitisation.

Regarding the use of the additive as preservative in feedingstuffs, the Panel concluded that ‘sodium formate had no discernible effects on microbial numbers in the feed materials examined’. In addition, no data were provided to support the efficacy as a preservative in water for drinking.

The applicant has now provided additional data to support the efficacy of sodium formate as a preservative in feedingstuffs for all animal species. No new data on the efficacy of sodium formate in water for drinking were provided.

3.1 Efficacy

The endpoints to demonstrate the efficacy of an additive in the functional group preservatives is ‘inhibition of microbial growth, particularly that of biotic and spoilage organisms. The period for which a preserving effect is claimed shall be demonstrated’.44 Commission Regulation (EC) No 429/2008 of 25 April 2008 on detailed rules for the implementation of Regulation (EC) No 1831/2003 of the European Parliament and of the Council as regards the preparation and the presentation of applications and the assessment and the authorisation of feed additives. OJ L 133, 22.5.2008, p. 1.

To support the efficacy of sodium formate as preservative in feedingstuffs for all animal species, three in vitro studies were provided.

3.1.1 Study 1 – Totally mixed ration

In the first study,55 Technical dossier/Supplementary information (February 2020)/ Annex 1_Final report PERSTORP Na‐formate 2019‐2020_20200214.
a totally mixed ration (TMR) was prepared with 76% grass silage, 20% sugar beet pulp and 4% straw. The dry matter (DM) content was approx. 52%. Three representative samples of the TMR were collected at study start to determine DM content, pH, and yeasts, moulds and total aerobic counts. The TMR was either left untreated (control, six replicates in test tubes of 1,300 mL) or treated with 3.0 g sodium formate/kg fresh TMR (six replicates). These samples were exposed to an aerobic environment at ambient temperature (20 ± 2°C) while their core temperatures were monitored. The lower end of the tubes was covered with an autoclaved, woven fabric to allow air to pass through. Sample temperatures were recorded every second hour for a period of 46 h.

Three replicates for each treatment were removed and analysed for pH, yeasts, moulds and total aerobic counts when the control samples went 5°C above the ambient temperature (T1). The remaining samples were analysed when the treated TMR reached the same temperature difference (T2). The data were analysed statistically using a one‐way analysis of variance (ANOVA). Significance was set a P < 0.05.

T1 was reached at 22 h after the start of the trial, T2 was reached 24 h after T1. At T1, treated samples, compared to the control, showed significantly lower pH values (3.94 vs 4.12), significantly lower counts for yeasts (6.44 vs 7.35 log colony forming units (CFU)/g) and total aerobic (6.87 vs 7.76 log CFU/g). At T2, the differences in pH became more marked (4.59 vs 7.53) but did not remain significant for yeast counts (7.00 vs 7.04 log CFU/g). Total aerobic counts of the sodium formate group were 8.29 log CFU/g, the control samples showed an overgrowth, therefore the results could not be compared. Moulds were not detected in any sample.

3.1.2 Study 2 – Beet pulp

In the second study,55 Technical dossier/Supplementary information (February 2020)/ Annex 1_Final report PERSTORP Na‐formate 2019‐2020_20200214.
that followed the same protocol described for Study 1, beet pulp (26.9% DM) samples (700 g fresh matter (FM) each, in eight test tubes of 1,300 mL each) were stored at ambient temperature (20 ± 2°C) and were analysed for aerobic stability and DM content, pH, and yeasts, moulds and total aerobic counts.

At T1 (22 h after the start of the study), no differences in pH were observed in treated samples compared to the control (3.71 vs 3.76), but treated samples showed significantly lower counts for yeasts (6.48 vs 8.24 log CFU/g) and total aerobic bacteria (6.08 vs 8.03 log CFU/g) than the control. At T2, that was reached 24 h after T1, the differences in pH became significant (3.97 vs 4.51). However, neither yeasts counts nor total aerobic bacteria were significantly different between the treated and the control samples (7.97 vs 7.88 log CFU/g and 8.01 vs 8.20 log CFU/g respectively). Moulds were not detected in any sample.

3.1.3 Study 3 – Distiller's grains (thin stillage)

Distiller's grains (thin stillage) as a high moisture feed ingredient (containing approx. 8.6% DM), was taken for the third study.55 Technical dossier/Supplementary information (February 2020)/ Annex 1_Final report PERSTORP Na‐formate 2019‐2020_20200214.
Distiller's grains were mixed with sodium formate at 0 or 3.0 g/kg FM. Twelve test tubes (500 mL, filled with 250 mL distiller's grains) for each treatment were stored at ambient temperature (20 ± 2°C). Once a day, samples were mixed manually for approximately 10 min to homogenise and to increase the aeration intensity. Four tubes per treatment were removed and analysed for pH, yeasts, moulds and total aerobic counts after 17, 25 and 30 days (T1, T2 and T3).

No differences in pH were observed at days 17 and 25, but the treated distiller's grains had a lower pH compared to the control at day 30 (4.84 vs 5.22 respectively). Yeast counts of the control group at T1 and of the sodium formate group at T2 showed an overgrowth; therefore, the results could not be compared to the respective groups. At T3, the sodium formate group showed significant higher yeast counts compared to the control (3.73 vs 0 log CFU/g). Total aerobic bacteria counts were lower in the treated group compared to the control only at T1 (0 vs 7.22 log CFU/g, respectively). Moulds were not detected in any sample.

4 Conclusions

The results of three in vitro studies with compound feedingstuffs and feed materials showed that sodium formate significantly improved some of the endpoints measured, although the effects were variable over time and feed/feed material. Considering the overall results of the three studies, the FEEDAP Panel considers that sodium formate has the potential to be efficacious as a preservative in feedingstuffs for all animal species at the proposed conditions of use. In the absence of information on the efficacy of sodium formate in water for drinking, the FEEDAP Panel cannot conclude on the efficacy of the use of the additive in water.

5 Documentation as provided to EFSA/Chronology

Date	Event
02/03/2020	Dossier received by EFSA ‐ Sodium formate. Submitted by FEFANA asbl
06/03/2020	Mandate received by EFSA
07/05/2020	Opinion adopted by the FEEDAP Panel. End of the Scientific assessment

Abbreviations

ANOVA

analysis of variance

CFU

colony forming unit

DM

dry matter

FEEDAP

EFSA Panel on Additives and Products or Substances used in Animal Feed

FM

fresh matter

TMR

totally mixed ration