Organic acids (OA) have shown promising results when it comes to ensuring that nutrients in the diet are digested by animals and not by pathogenic bacteria, in a two-part strategy: One strategy is to control pathogenic microbiota in the first part of the GIT and thus reduce the harmful bacteria reaching the hind gut. The second strategy is to improve nutrient digestion, especially protein, so that less food for pathogenic bacteria reaches the hind gut.
Global Product Manager Gut Health
Selko
You’ve probably heard the phrase, “you’ve got to feed the beast,” but who wants to feed harmful bacteria? Feed ingredients can either feed the animal and result in improved performance or serve as nourishment for harmful microbiota in the gastrointestinal tract (GIT) that can lead to reduced performance and even diarrhoea.
Organic acids (OA) have shown promising results when it comes to ensuring that nutrients in the diet are digested by animals and not by pathogenic bacteria, in a two-part strategy: One strategy is to control pathogenic microbiota in the first part of the GIT and thus reduce the harmful bacteria reaching the hind gut. The second strategy is to improve nutrient digestion, especially protein, so that less food for pathogenic bacteria reaches the hind gut. Did you know that E. coli loves undigested protein?
Research studies have demonstrated that blends of OA support multiple functions inside the animal that promote better digestion and absorption of nutrients. These functions include reducing the pH in the GIT (Table 1), promoting digestive enzyme activity, altering intestinal morphology (Table 2), and optimizing nutrient digestibility, among others. Furthermore, the specific combination of OA works to support the gut microbial balance by enhancing the growth of beneficial bacteria and inhibiting pathogenic bacteria. Inhibiting the growth of harmful bacteria increases nutrient availability for the animal.
WATER ACIDIFIER – OA CAN ALSO BE APPLIED VIA WATER
Trouw Nutrition developed a complete portfolio of feed additives based on blends of OA that support animals’ stomach acidification and gut health. Selko® AlpHa, a Selko® water acidifier (SWA), is a synergistic blend of OA applied via water. SWA is a blend of free and buffered OA that effectively reduces and stabilises water pH. Inside the animal, it supports protein digestion by reducing the pH in the stomach. The multi-function SWA also supports a stable intestinal microbiota and helps sustain animals’ health so that they can deliver optimal performance.
OA SUPPORT STOMACH ACIDIFICATION – WHAT STUDIES SHOW
Animals’ digestive enzymes degrade feed nutrients into absorbable molecules. Both the activity of these enzymes and the microbiota population in the GIT are influenced by pH. The conversion of pepsinogen into pepsin, the enzyme that digests protein, is pH dependent, and the conversion process occurs rapidly when the pH is between 2.0-3.5.1 A low pH – below 4- delivers a bacteriostatic effect against many pathogenic bacteria including E. coli, Salmonella, and Clostridium. Young animals’ present special challenges as their GITs are still immature, especially in terms of pH. Below, we look at some OA studies Trouw Nutrition conducted involving broiler and piglet diets.
Broilers: In the week following hatch, the secretion and activity of digestive enzymes and the surface area for absorption are limiting factors. These limitations are overcome as the birds grow older. Different authors have observed that the GIT pH undergoes changes during the production cycle.2,3 The pH in the crop, gizzard, proventriculus, and small intestine slowly declines from day 0 to day 7. This decline is followed by an increase from d 14 to d 42. Although digestive secretions and HCl production are expected to increase as the bird ages, the pH increase beyond day 14 is probably a reflection of the broiler’s increased consumption of feed with neutral pH. The feed’s buffer capacity is also a major determinant of intestinal pH.
Trial takeaway: A 35-days study performed by Trouw Nutrition tracked the GIT pH of broilers and showed that the SWA reduced the pH in the crop, proventriculus, and duodenum (Table 1).
Piglets: In suckling piglets, the principal source of stomach acidity is the bacterial fermentation of the lactose in sow’s milk into lactic acid (which inhibits HCl secretion). However, at weaning, the stomach pH is high, often above pH 5.0. In the first weeks after weaning, HCl production is not yet sufficient, and pepsin activity only begins to increase when piglets reach 5-6 weeks of age (5.7 vs 17.0 U/g of mucosa).4,5 Factors causing this situation include the piglet’s dietary change from milk to solid feed (reduction of lactic acid and slow production of HCl), the change in the pattern of feed intake (consumption of large meals at infrequent intervals), and the high buffering capacity of the feed. Newly weaned piglets require a relatively low stomach pH (around 3) for the digestion of plant- and animal-derived proteins (other than milk).
Trial takeaway: A meta-analysis of three studies conducted by Trouw Nutrition shows that piglets receiving SWA saw a reduced stomach pH
(Table 1).
As noted earlier, a high stomach pH can impede digestion of feed ingredients. The undigested nutrients can ferment in the hindgut where surviving pathogens have a greater opportunity to colonise the digestive tract. Ultimately, these conditions may result in diarrhoea. If the stomach pH is not lowered, pathogenic bacteria (as E. coli) dominate while beneficial bacteria (such as Lactobacillus) decline. On the other hand, a low stomach pH favours the growth of Lactobacillus, which inhibits the colonisation and proliferation of some harmful bacteria, such as E. coli.6
Trial takeaway: In a 35-days study involving weaned piglets, a significantly lower percentage of animals supplemented with an SWA had a faecal score of 3 and 4 (pasty and liquid faeces) compared to piglets in the control group (10.7 vs 4.4%, P < 0.05).
INTESTINAL MORPHOLOGY: A GOOD INDICATOR OF A HEALTHY GUT
The small intestine is responsible for the final digestion and absorption of nutrients. Villi are critical components of the small intestine, and their geometry provides an indicator of its absorptive capacity. The villus height (VH) and the crypt depth are useful criteria for assessing intestinal health and function.7 Furthermore, changes in villi surface area may enhance predisposition to malabsorption, enteric infections, and diarrhoea.8
Trial takeaway: In two different studies conducted with broilers and piglets, it was observed that supplementation of a SWA resulted in higher VH (Table 2).
The studies described above – and many more conducted at Trouw Nutrition research centers and on commercial farms around the globe – demonstrate that OA blends can support gut health, along with better protein digestion, resulting in growth of broilers and piglets (Figure 1).
References
1. Bohak, Z. Chicken pepsinogen and chicken pepsin. Methods Enzymol. 1970, 19:347–358.
2. Mahagna, M. & Nir, I. Comparative development of digestive organs, intestinal disaccharidases and some blood metabolites in broiler and layer-type chicks after hatching. 1996. Br. Poult. Sci. 37:359–371.
3. Barua, M., et al. An investigation into the influence of age on the standardized amino acid digestibility of wheat and sorghum in broilers. 2021. Poult. Sci. 100:101466.
4. Cranwell, P. D. 1985. The development of acid and pepsin (EC 3.4.23.1) secretory capacity in the pig; the effects of age and weaning: 1. Studies in anaesthetized pigs. Bri. J. Nutri. 54:305–20.
5. Lindemann, M. D. et al., 1986. Effect of age, weaning and diet on digestive enzyme levels in the piglet. J. Anim. Sci. 62:1298–1307.
6. Barrow, P. A. et al. 1977. Changes in the microflora and physiology of the anteriorintestinal tract of pig weaned at 2 days with special reference to the pathogenesis of diarrhoea. Infect. Immun. 18:586–595.
7. Pluske, J. R. et al. 1997. Factors influencing the structure and function of the small intestine in the weaned pig: a review. Livestock Production Science 51: 215-236.
8. McCracken, B. A. et al. 1999. Weaning anorexia may contribute to local inflammation in the piglet small intestine. Journal of Nutrition 129: 613-619.
