Organic acids in swine: their use in modern, market driven animal nutrition. Introduction Organic acids are proposed as one of the GRAS (Generally Recognized as Safe) alternatives to antibiotics. Several organic acids (viz. formic, fumaric, malic, citric, acetic, benzoic, gluconic, butyric and propionic acids) are used in animal industry. Organic acids are used in feed and grain preservations, as antimicrobials and also silage inoculants. Organic Acids and their salts can be used to maintain animal health and performance, and as such have been used as part of a program to replace sub-therapeutic antibiotic growth promoters. Their mode of action includes stimulating gastric enzyme secretion, nutrient digestibility and retention, leading to improved feed conversion rate and daily gain (Baustadt 1993). Economic benefits result from a reduction in feed costs and a shorter time to market (Diebold, Eidelsburger 2006). The growth performance could be attributed to improved energy, crude protein or amino acids digestibility and reduced detrimental bacterial populations and their metabolites in the gastrointestinal tract (Blank et al. 1999). Organic acids are supplemented as on top in animal feed industry. Application and improvement of energy and nutrient digestibility coefficients of a diet, caused by organic acids, could increase its economy based incorporation in least cost feed formulations. Meta-analysis: A meta-analysis was performed by collecting all information on the following parameters: organic acid type and its concentration, type of pig (age and weight), origin of study, number of animals, treatment effects and statistical attributes (Table below). Other information such as diet types and diet characteristics was also recorded. Based on an analysis of published data, the growth promoting effect of formates, fumarates and citrates did not differ in weaned piglets. In fattening pigs, formates were the most effective followed by fumarates, whereas propionates did not improve growth performance. These mentioned acids improved the feed : gain ratio of both weaned piglets and fattening pigs (Partanen, Morz 1999). Table 1. Response of weaned piglets and fattening pigs to dietary organic acids or their salts according to the metaanalyses published data The results of the meta-analysis indicated that citric, formic and fumaric acid improved (P < 0.01) and propionic acid reduced (P < 0.01) faecal digestibility of crude protein. Ileal crude protein digestibility was improved by butyric and fumaric acid (P < 0.01). Digestibility of lysine and dry mater was not affected (P > 0.05) by organic acids. Organic acids also improved the performance (P < 0.01) of piglets. In grow finisher pig s dietary sorbic acid improved (P< 0.01)
weight gain (66 g/d) in grower-finisher pigs. Also, formic acid (-0.11) and sorbic acid (-0.15) led to improvement in FG (P < 0.01) and formic acid also led to improvement in GF (0.014). In finisher pigs, benzoic acid (-0.08), formic acid (- 0.07) and sorbic acid (-0.09) improved FG (P < 0.01). Organic acid supplementation was initially targeted for weaned piglets. The data affirmed an overall positive influence of organic acid data on faecal digestibility of crude protein and performance of piglets. Dietary acidification is also beneficial for the performance of fattening pigs. Several studies have indicated that in fattening pigs, organic acids improved the apparent ileal digestibility of protein and amino acids contributing to improved performance (Mosenthin et al. 1992; Kemme et al. 1995; Morz et al. 1997). Table 2. Summary of acid effects on growth rate in weanling, growing and finishing pigs. Description Number of observations Mean, %a Total positive negative equal Pb weanling piglets 0-2 weeks post-weaning 12.25 50 36 12 2 0.0002 0-4 weeks post-weaning 6.03 78 59 17 2 0.0001 growing pigs 3.52 30 19 11 0 0.0150 finishing pigs 2.69 9 8 1 0 0.0220 a Mean percentage difference between average daily gain of pigs fed the diet containing acid versus those fed the control diet. b Probability of no difference from zero Table 3. Summary of acid effects on growth rate in pigs challenged with stress and disease.. Description Number of observations Mean, %a Total positive negative equal Pb Challenges 9.35 11 10 1 0 0.006 a Difference between acid and control treatments, expressed as % of control value. b Probability of no difference from zero Tables 2 and 3: C.M. Tung and J.E. Pettigrew, 2010. Pork Checkoff- Critical Review of Acidifiers, Department of Animal Sciences, University of Illinois. Trouw nutrition research: Trouw Nutrition is part of Nutreco and innovation is what binds them together. At our 11 R&D centres around the world, some 250 experts are continuously working on developing new insights on how to improve lifestart, health and welfare and feed efficiency. We have 2 research facilities where swine research is performed: Agresearch in Canada and our newest facility the SRC (Swine research center) in Holland, where we also have an animal health unit to perform challenge trials. This gives us the unique opportunity to intensely study the impact of different feed additives on challenges known to be present in swine, such as Salmonella, E.coli and Clostridium. One of the projects that is running is a project to develop a strategy against Salmonella and E. coli. A first step in this research was to set-up a valid infection model. After developing this model we looked in to the different ways you can interfere with bacteria. Looking at the bacteria itself you can decrease either its virulence, its metabolism, its adhesion
Body temperature or its membrane function. Within the animal you can for example stimulate beneficial bacteria or increase IgA production. At one point in this research we looked at Selko-pH. Selko-pH is a liquid feed additive. Its positive effect on performance is achieved in 3 steps: effectively reducing water ph, supporting digestion and improving microbial balance. In this trial a non-infected group was compared to an infected group of piglets that either did or didn t get Selko-pH added to the drinking water. One of the parameters that were found to indicate if the infection was successful was a temperature increase. In both infected group this increase was seen, in the non-infected group we did not get this increase. (Figure 1) 40.0 39.8 39.6 39.4 39.2 39.0 38.8-10 -5 0 5 10 15 20 25 Days post infection non-infected infected infected + Selko-pH Figure 1. Average body temperature after infection Looking at fecal Salmonella shedding by the animals a1.4 log decrease (p=0.015) was seen in the Selko-pH group compared to the infected group that didn t get anything in the drinking water. (Figure 2) Figure 2. Fecal Salmonella shedding after infection Next to that the treatment was able to prevent the impaired feed efficacy caused by the Salmonella infection (Figure 3).
Growth/feed intake 1.4 1.2 1 0.8 0.6 0.4 0.2 0 P<0.10-7 0-7 7-14 Days post infection non-infected infected infected + Selko-pH Figure 3. Feed efficiency before infection, 0 to 7 days after infection and 7 to 14 days after infection. Conclusion: By using organic acids in the drinking water we were able to decrease the salmonella shedding by pigs with 1.4 log in our infection model. Also we showed that this approach can prevent the negative impact of Salmonella infection on feed efficiency. After testing this in our infection model, several field trails were conducted that showed similar results. References: Allaart, J., Roubos, P., Teirlynck, E., Eissen, J. and GD Animal Health team (2016), Administration of an acidifier (Selko-pH) via drinking water reduces shedding of Salmonella typhimurium in challenged piglets, IPVS, Dublin, Ireland. Baustadt, B. (1993) Effects of formic acid on performance in growing pigs. Norwegian Journal of Agricultural Sciences 7: 61-69. Blank, R., R. Mosenthin, W. C. Sauer, & S. Huang. 1999. Effect of fumaric acid and dietarybuffering capacity on ileal and fecal amino acid digestibilities in early-weaned pigs. Journal of Animal Science 77: 2974-2984. Diebold, G. and Eidelsburger, U. (2006) Acidification of diets as an alternative to antibiotic growth promoters. In: Antimicrobial growth promoters. Edited by D. Barug, J. de Jong, A.K Kies and M.W.S. Verstegen. Pp. 311-327. Wageningen Academic Publishers, Wageningen, The Netherlands. Morz Z, Jongbloed AW, Vreman K, Canh TT, van Diepen JThM, Kemme PA & Kogut J (1997) Apparent digestibility of amino acids and balance of nitrogen and minerals as influenced by buffering capacity and organic acids in diets for growing swine. Journal of Animal Science 75, Suppl. 1, 185 Abstr. Mosenthin R, Sauer WC, Ahrens F, de Lange CFM & Bornholdt U (1992) Effect of dietary supplements of propionic acid, siliceous earth or combination of thes on the energy, protein and amino acid digestibilities and concentrations of microbial metabolites in the digestive tract of growing pigs. Animal Feed Science and Technology 37, 245-255.
Partanen, Kirsi H. and Mroz, Zdzislaw. (1999) Organic acids for performance enhancement in pig diets. In: Nutrition Research Reviews 12, 117-145. Tung, CM and Pettigrew, JE (2010). A critical review of acidifiers. Pork Checkoff.