From the August 2001 Pork News & Views Pork News and Views is prepared by the Swine Advisory Team of the Ontario Ministry of Agri- culture, Food and Rural Affairs Editor: John Bancroft Clinton OMAFRA, 519-482-3133,

In EU countries, the use of antibiotics for enhancing animal production has been banned. In the U.S., the American Medical Association's policymaking House of Delegates approved a resolution at its annual meeting in June urging that "non-therapeutic" use of antibiotics in animals be phased out or eliminated. The measure refers specifically to antibiotics that are given to humans as well. It wants the government to phase out the overuse of antibiotics in livestock, broadening the organization's campaign to curb human resistance to lifesaving drugs. Antibiotic use in livestock production is under government review and measures to control drug resistance is under development. In Canada, the use of Carbadox is currently under Health Canada. s review and facing a possible ban. Therefore, it is clear that the use of antibiotics in animal production will become more and more restricted and alternatives to antibiotic growth promoters need to be investigated and deployed.

As a result, research is continually being conducted to study alternatives for replacing antibiotics. Alternatives under studying range from herbs, probiotics, prebiotics and organic acids to chemical supplements and management tools. Numerous studies have demonstrated that formic acid is effective against pathogenic bacteria. In practice, however, due to the problems of handling, strong odor and corrosion to feed processing and feeding and drinking equipment, its use is limited. To overcome the problems, potassium diformate (K-diformate) has received attention as an alternative to formic acid because it is easier to handle than the pure acid, while it has been shown effective in enhancing growth performance of both weaner and grower-finisher pigs. A study conducted by researchers at the Agricultural University of Norway (J. Anim. Sci. 2000. 78:1875-1884) showed that dietary supplementation of K-diformate at 0.6-1.2% levels improved growth performance, carcass quality and meat safety in grower-finisher pigs without negative effects on sensory pork quality. It was also showed that unlike K-diformate supplementation of Ca/Na-formate had no effects at all on growth and carcass quality.

In this study, a total of three experiments were conducted. In experiment one, 72 pigs (23.1 kg initial body weight and 104.5 kg body weight) were assigned to three diet treatments (Control, 0.85% Ca/Na-formate and 0.85% K-diformate). Results showed that the K-diformate diet increased overall average daily gain (ADG) but had no effect on average daily feed intake (ADFI) or gain/feed (G/F) ratio. Carcass lean or fat content was not affected by either K-diformate or Ca/Na-formate.

In experiment two, 10 pigs (initial BW: 24.3 kg, final BW: 85.1 kg) were used to study the effect of K-diformate on performance and sensory quality of pork. All the pigs were on a limit-fed feeding regime and fed the same diets except for adding 0.8% K-diformate in the treatment group. Results showed that supplementing K-diformate to diets increase ADG and G/F, but it had no effect on sensory quality of the pork.

In experiment three, 96 pigs (initial BW: 27.1 kg, final BW: 105kg) were assigned to three diet treatments, containing 0, 0.6% and 1.2% K-diformate respectively, to study the effect of supplementing K-diformate in diets on growth performance, carcass traits and, microflora of the gastrointestinal tract. The results showed that supplementation of K-diformate at 0.6% and 1.2% level increased growth performance, reduced fat content and improved carcass lean percentage. It was found that adding K-diformate reduced the number of coliforms in gastrointestinal tract of the pigs, therefore, improving pork safety.

Table 1. Effect of dietary supplementation of Ca/Na diformate and K-diformate on growth performance in Experiment 1
	Item	Control	Ca/Na-formate	K-diformate
Growing period	ADG, g	752	758	797
	G/F	.444	.447	.461
Finishing period	ADG, g	1,118	1,099	1,130
	G/F	.377	.369	.373
Overall period	ADG, g	917	911	942
	G/F	.406	.401	.410

Table 2. Effect of dietary supplementation of K-diformate on growth performance in Experiment 2
	Item	Control	0.8% K-diformate
Growing period	ADG, g	855	957
	Gain/Feed	.436	.468
Overall period	ADG, g	883	987
	Gain/Feed	.419	.450

Table 3. Effect of dietary supplementation of K-diformate on growth performance and carcass traits in Experiment 3
		K-diformate
	Item	0 %	0.6%	1.2%
Growing period	ADG, g	748	793	828.
	Gain/Feed	.401	.412	.415
Finishing period	ADG, g	980	986	1,014
	Gain/Feed	.327	.324	.330
Overall period	ADG, g	863	886	915
	Gain/Feed	.357	.360	.367
	Carcass Wt, kg	74.4	75.4	75.1
	Lean yield, %	54.1	54.1	54.9