Potassium diformate (FORMI) and 3rd generation acidifiers in antibiotic-free feeding - impacts in sows and piglets

Friday, July 2, 2021

Potassium diformate (FORMI) and 3rd generation acidifiers in antibiotic-free feeding - impacts in sows and piglets

Christian Lückstädt and Ryan von de Leon; ADDCON, Bitterfeld, Germany



With costs of pig production under increasing pressure, the nutrition of young pigs is of increasing interest, as this period is critical to the subsequent performance of the animals through to market. Optimising growth rate and feed efficiency at this time are key requirements for success in today's animal production systems. While antibiotics are available to assist in improving growth during this phase, there are a range of concerns about their use from pig producers across the globe, including bacterial resistance, palatability and the accuracy of antibiotic dosage if feed intake is compromised. Currently, the use of antibiotic growth promoters (AGPs) is under increasing scrutiny from consumers and legal authorities, also in Asia. The ban on in-feed AGPs has been decided and implemented for instance in South Korea, Vietnam and Indonesia as well as in China. Other countries in the region are about to follow. According to the WHO (2019), each year some 700,000 people worldwide die as a result of infection with drug-resistant bacteria. A joint report by the European Food Safety Authority, the European Medicines Agency and the European Centre for Disease Prevention and Control (2017) reported further evidence of a link between antibiotic use and antibiotic resistance. The report found that even though the EU had already banned the use of in-feed antibiotics back in 2006, their use to date in poultry and livestock is still higher than in humans. So even Europe, not to mention the other prominent areas of the world with intense animal production, needs to work on the responsible use of antibiotics. This led to the European Commission funded "European One Health Action Plan against Antimicrobial Resistance (AMR)". This One Health approach, recognizing that human and animal health are interconnected, is seen by the WHO and the EU as the only viable solution to tackle antimicrobial resistance (AMR). As part of this plan, the EU adopted just last year new legislation on monitoring AMR in zoonotic and commensal bacteria in farm animals and food (EU AMR Action Plan, 2020).

The animal feed additive sector is greatly involved, and various feed additives have been studied as alternatives for in-feed AGPs. Organic acids, particularly salts of organic acids, have been reported by many experts to enhance growth performance in the absence of AGPs in pigs, as well as in poultry and aquaculture. Experience has shown that acidifiers are the most reliable product group of the non-antibiotic growth promoters available, as reported by Papatsiros and Billinis (2012).

The potential application of organic acids to livestock nutrition and forage preservation has been known for decades and is documented by many scientific studies, which have also elucidated their mode of action. Despite this, most of the available acids to the industry have an authorization as feed preservatives only. One of these, formic acid, is reported as being the strongest organic acid against pathogen Gram-negative bacteria (Strauss and Hayler, 2001); however its practical use in feed production is limited by its unfavourable pungent smell and corrosiveness.

The potassium salt of formic acid, potassium diformate (KDF, traded as FORMI, ADDCON), on the other hand, also has a strong anti-microbial effect, but is proven safe for humans and has no adverse smell. In contrast to formic acid, potassium diformate is a solid product, which is non-corrosive. Because of its unique and patented chemical structure, KDF combines the chemical properties of both an acid and a salt. FORMI was the first EU registered zootechnical additive for sows, piglets and fatteners to improve growth and health performance at all stages along the pig production chain, the natural way – thus ADDCON is proud to be one of the first supporters of the AMR Action Plan by delivering non-antibiotic solutions to the world-wide livestock industry.

The impact of FORMI as a potential antibiotic-replacement has been tested world-wide. In a trial in Spain, published by Portocarero-Khan et al. (2006), it was found that the inclusion of KDF into the diet of weaned piglets (day 28) led to a numerical improvement of daily gain and feed efficiency compared with Colistin until day 40, whereas a significant reduction in diarrhoea rate (0.7% vs. 14.6% for KDF and Colistin respectively) was noticed by day 60. It was concluded that an improved gut health promoted by KDF was the cause of the improved parameters.

The first Asian trials appeared in 2004 and the additive has been widely used as a natural growth promoter in Asia ever since. The following trials from Asia prove the aforementioned beneficial effects on growth performance, also in the absence of AGP.

A trial (Lückstädt et al., 2012) under tropical conditions in Vietnam measured the performance enhancing impact of KDF at low dosages, compared to AGP's. Eighty 28-day old weaned piglets of equal weight (initial weight 10.1 kg), gender and breed, were allocated to 4 equal groups with 20 piglets each. Piglets were kept at an experimental farm in Southern Vietnam for 28 days, receiving a commercial diet of 19% crude protein with 2975 kcal kg-1 metabolisable energy (ME). Diet 1 served as a negative control, while diets 2 to 4 contained either 0.4% KDF, 300 ppm Bactrim or 120 ppm Colistin. Feed and water were available ad libitum. At the end of the trial, final weight, daily weight gain, feed conversion and the diarrhoea rate of piglets were obtained and analysed using ANOVA (P<0.05).

The final weight of piglets fed 0.4% KDF was significantly increased compared to the control whereas the inclusion of Bactrim or Colistin led only to intermediate results between the control and KDF. Furthermore, a numerical improvement of the feed conversion ratio by 16% was monitored – due to the design of the trial no statistics could be carried out. Finally, the overall days of diarrhoea per group were significantly reduced in the KDF-treatment from 49 d (control) to only 22 d. Similarly, a significant diarrhoea reduction was obtained in the Colistin-group, however, this was not as pronounced as in the KDF-fed group (Table 1).


Table 1.  Performance parameters and diarrhoea rate of piglets fed KDF and different AGP (modified after Lückstädt et al., 2012)*


The findings of the aforementioned studies from Europe and Asia and the wide-spread commercial use support the application of dietary KDF as an effective and sustainable growth-promoter in post-weaned piglets. It is therefore safe to say that 'dietary acidifiers can actually become the most common and efficacious alternative solution to antibiotics, in order to improve health status and performance of pigs' (Papatsiros and Billinis, 2012). The available data show that this statement is especially true for potassium diformate!


However, while the antimicrobial impact of organic acids and their salts, including potassium or sodium diformate, is mainly directed against Gram-negative bacteria like Salmonella or E. coli, medium chain fatty acids (C-6 to C-12) have also been shown to have an antibacterial impact against various Gram-positive bacteria(Preuss et al., 2005). This is especially true for lauric acid (C-12) and its monoglyceride ester, monolaurate. Lauric acid has the greatest antibacterial activity of all medium chain fatty acids. This effect is magnified if monolaurate is used(Batovska et al., 2009), making it a promising candidate as an additive or as an alternative to antibiotics for treatment of different diseases(Rouse et al., 2005).

This formed the impetus for the current research, which led to the development of 3rd generation acidifiers, like FORMI 3G (ADDCON) – which is based on the patented and trusted diformate concept, complemented with the broader impact coming from the medium chain fatty acids and their salts. The study tested the efficacy of the diformate and monolaurate agglomerate on their decontamination impact on Gram-negative and Gram-positive bacteria in sow faeces.

600 sows on a commercial farm in Lower Saxony, Germany, were fed from the 100th day of gestation a special gestation feed containing 1.2% diformate-monolaurate combination. Prior to that, on the 90th day of gestation, faecal samples of sows had been collected and sent for microbial analysis to the Veterinary University of Hanover. Samples of sow faeces were analysed for E. coli and Streptococci / Enterococci counts. The feed containing the additives was given to the sows until the 4th day of lactation. Thereafter, faecal samples were collected and analysed again from the same sows.

Results of the microbial analysis revealed a strong impact of the product on the bacterial population in the faecal matter of sows (Table 2). This holds true for both E.coli and Streptococci / Enterococci counts.


Table 2:  Bacterial counts (CFU/g) in sow faeces before and after feeding with 1.2% diformate-monolaurate and their respective reduction rates in percent



The reduction rate of the E. coli count in the faeces was above 90%. It varied between 83% and 100%. However, the reduction of the Streptococci count within the trial period was highly significant (97%; P<0.01) and varied from 89% to 99.9%. The combined inclusion of diformate and monolaurate therefore not only provide a healthy gut in sows, but will furthermore support the piglets indirectly during the suckling period by providing "clean" conditions and thus greatly reducing the spread of E.coli and Streptococci towards the new-born piglets, which would lead to improved performance. Trials proving this assumption (e.g. substantial impacts on number of weaned piglets, average daily gain and litter weaning weight as well as microbiome and gut health impacts) have been published world-wide during the last couple of years (for instance at SafePork, Germany 2019; Kansas State University 2019 and 2021; Recent Advances in Animal Nutrition, Australia 2021). 

To conclude, the agglomerate of diformate and monolaurate caused a significant improvement in the health status of sows. The impact against the Gram-positive Streptococci is especially noteworthy. In general, it can therefore be stated that the above findings support the use of Formi 3G – or, potassium diformate (Formi) as an effective and sustainable tool in improving gut health in sows and has furthermore a supporting function for the EU-antibiotic reduction initiatives – the One Health Action Plan on swine farms.



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Article made possible through the contribution of Christian Lückstädt, Ryan von de Leon and ADDCON