In 2020, China banned the addition of antibiotic growth promoters in feed, which will surely promote the use of antibiotic substitutes in animal breeding. In 2001, the European Union approved potassium diformate as a feed additive. In 2005, the Ministry of Agriculture of China approved that potassium diformate can be used in pig feed [Xinshizhengzi (2005) No. 03]. Because of its no residue, no toxicity and no drug resistance, potassium diformate has been widely used in animal breeding as an antibiotic substitute for bacteriostatic and growth-promoting agents.

1. Physical and chemical properties and safety of potassium diformate

Potassium diformate is an organic substance with a molecular formula of C2H3KO4 (HCOOH-HCOOK) and a molecular weight of 130.14. It is connected by formic acid and potassium formate through hydrogen bonds. Powder, melting point is 108.6 ℃. Potassium diformate is very easy to absorb water and deliquescence, and its aqueous solution is acidic. Under acidic conditions, potassium diformate is relatively stable and not easy to dissociate. Under weak alkaline or neutral conditions, potassium diformate is easily decomposed into formic acid and potassium formate. After decomposition, formic acid can dissociate hydrogen ion (H+) and carboxyl group (HCOO), and potassium formate can dissociate potassium ion (K+) and carboxyl group (HCOO).

Potassium diformate has high safety to living organisms and the environment, and does not induce bacterial resistance. Potassium diformate has no residue in animals, and the acute toxicity test and subacute toxicity test of oral and inhalation show that potassium diformate is safe for animals and has no genotoxicity. After the application of potassium diformate, the nitrogen and phosphorus excretion of the animal body can be reduced, thereby reducing the harm to the ecological environment.

2. The functional mechanism of potassium diformate

1) Reduce the p H value of the digestive tract and regulate the activity of digestive enzymes. Potassium diformate is decomposed in the digestive tract to generate formic acid and potassium formate, and then further dissociates to generate K+, H* and HCOO.H*, which can adjust the acidity and alkalinity and reduce digestion. It regulates the secretion and activity of various digestive enzymes such as pepsin and trypsin, and promotes protein digestion and absorption, thereby promoting the growth and development of animal bodies.

2) Promote food intake and nutrient digestion. Potassium diformate can stimulate animal feed intake and increase feed intake. K+ is an essential substance in the process of animal growth and metabolism (Wang Danhong et al., 2013), which can improve the utilization of lysine. The decrease of pH value in the stomach can stimulate the secretion of pepsinogen and pepsin, and stimulate the duodenum to secrete more trypsin, thereby improving the digestion and absorption of dietary nutrients, and also reducing the excretion of nitrogen and phosphorus. The bacteriostatic effect of potassium diformate reduces the number of microorganisms, which can reduce the competition of microorganisms for nutrients, and the nutrients that can be used by the host are relatively rich, which can improve the growth rate and feed conversion efficiency of animals (Huang Xiaochun et al., 2006).