The main objective of animal husbandry is an efficient and sustainable conversion of feed into milk, eggs and meat for human consumption. Hence the role of the gut and its health status is crucial for an optimal production result. The gut is responsible for digestion and absorption of nutrients, but many challenges lurk around the corner that lower the genetically driven conversion of feed into animal protein.
Global Product Manager
Impextraco
The gut of farm animals from stomach to hindgut is an engine designed for processing compound feed and transferring it into the building blocks of animal proteins and essential metabolites. Being a connection with the outside world including the environment and the farm, the intestine is in close contact with many challenges that come together with the feed or just after oral intake. Hence its function requires facilitation by the king’s guard, a.k.a. the immune system, and a friendly guest, a.k.a. the gut microbiome.
The immune system’s primal role is to fight and conquer pathogenic micro-organisms that try to invade through the epithelium and cause diseases. The immune system should be sharp and swift, but cost-efficient as it competes directly with the conversion of feed into animal protein. Similarly, the gut microbiome consumes nutrients like protein and carbohydrates, but returns favorable metabolites that upregulate the gut functioning and lowers the pathogenic pressure.
YOUNG ANIMALS
The rate at which animals are raised puts a lot of pressure on their intestinal development. Many animals start with an empty gut and only receive some maternal immunity. For example, broilers have at hatch no functional adaptive immune response but receive some maternal immunoglobulins via the egg yolk and have developed their immune organs during the embryonic phase. Moreover, the gut microbiome is only limited to a number of bacteria in the early days and consequently very dynamic and sensitive for pathogenic colonization. Therefore, the aim is to reach a stable and diverse microflora as soon as possible. Furthermore, in the first days digestion and absorption of nutrients is limited. Digestive enzyme production is not at full capacity yet, just like HCl production in the stomach of the animal. Simultaneously, the intestinal epithelium is not fully developed resulting in short villi. In conclusion, the first challenge for an animal is to reach stable intestinal health, which is a balance between immunity, its gut microbiome and digestion and absorption of the diet. Establishing this equilibrium is already a challenge and we are not even talking about other threats like mycotoxins or environmental stress.
NUTRITION AS A TOOL
Nutrition is a tool to establish and maintain a proper intestinal health condition. Many measures can be implemented to optimize the diet for young animals. Especially in piglets, protein digestibility is important to avoid intestinal health problems after weaning. In piglets, stomach acid production is not sufficient resulting in a suboptimal protein digestion. Next, undigested protein is fermented by pathogenic bacteria in the hindgut resulting in endotoxin production and diarrheal incidence. To solve this, protein content and acid binding capacity of the piglet feed should be optimized. The protein content can be improved by selecting highly digestible protein sources instead of soybean meal. Some considerable options are soy protein concentrates, fermented soy protein or alternatives like milk protein, potato protein and fish meal. All these materials have a higher crude protein content and a higher digestibility compared to soybean meal. Simultaneously, the acid binding capacity of the diet should be lowered, which decreases stomach pH and increases protein digestion. Therefore, organic acids are standard in piglet diets. Key for piglets is to stimulate feed intake directly after weaning as this increases stomach acid secretion, digestive enzyme production and development of the intestinal epithelium. Generally, piglets that have a proper feed intake don’t show weaning diarrhea and have a higher body weight when they move to the finisher barn.
Comparable to piglets, broiler chickens’ intestinal development is stimulated upon feed intake, so early access to feed is very important. But as chickens receive little immunity from the yolk and their intestine is sterile, steering the gut microbiome with nutrition is important to avoid dysbacteriosis. Dysbacteriosis is an imbalance of the intestinal microflora, which results in overgrowth of detrimental bacteria followed by intestinal inflammation and dirty litter. Controlling digestive disorders starts with coccidiosis control as this is a predisposing factor for the development of dysbacteriosis. Next, it is required to breakdown the vicious circle starting from an oversupply of nutrients or poor digestion and absorption and resulting in a shift in the microbiome and an altered gut barrier morphology and functioning. Many nutritional strategies can help to break this circle. Optimizing the protein content and amino acid profile to avoid fermentation of undigested protein into harmful amines and ammonia drives the crude protein of broiler diets to a minimum. Moreover, the selection of cereals is important as they are a source of non-starch polysaccharides, like arabinoxylans, glucans and mannans. Typically, NSP-enzymes like xylanase are supplemented to the diet to release more nutrients for the animal and to reduce gut viscosity that impacts digestion and intestinal health directly.
IMPACT OF FEED ADDITIVES
Clearly, feed additives are an important nutritional tool when it comes to intestinal health. Above is described the importance of organic acids, when it comes to stomach acidification and acid buffering capacity, but their actions are much wider than this. For example, formic acid and propionic acid are very strong in controlling bacterial and fungal contamination of compound feed or raw materials. All organic acids have a pKa value that determines if they are antibacterial or will acidify the environment depending on the pH of the environment. Therefore, the right combination of different organic acids will be able to acidify and reduce the pathogenic load in the stomach of piglets. On top of that ACIDAL® NC is enhanced with a natural extract and a taste enhancer to work synergistically with the organic acids. A weaning piglet trial confirmed the beneficial effect of the organic acid blend. The feed conversion ratio during the pre-starter phase (day 21-35) was improved with 13 points compared to a control diet without organic acids. This implies that the piglet’s stomach functioning was improved, which resulted in an increased protein digestion and conversion into growth. Furthermore, feed intake was not different between both groups indicating that 5 kg/T ACIDAL® NC did not negatively influence the palatability of the diet.
Another organic acid, butyric acid, works directly in the intestinal tract. It is a metabolite for the epithelium cells, which is directly converted as an energy source. Hence this molecule promotes digestive enzyme secretion, villus development and gut barrier fortification in the epithelial cells. Moreover, it reduces gut inflammation and could lower the virulence of Salmonella. With these properties, butyric acid is very effective to establish a proper intestinal equilibrium in young animals. Moreover, it works synergistically with short or medium chain fatty acids, essential oils or natural extracts that possess antibacterial properties to achieve a complete intestinal protection. Butyric acid is supplemented in the feed either as a salt form or as a glyceride. The salt forms, sodium butyrate and calcium butyrate, are fat coated to bypass stomach conditions and avoid early liberation of butyric acid. Trials in broiler chickens confirm the role in intestinal development, but moreover show the contribution of proper intestinal health towards zootechnical performance. In a floor pen trial with 720 Ross® 308 male broilers, supplementing a control diet with coated calcium butyrate (Butifour® CCB) resulted in a significant improvement on final body weight. Simultaneously, it was shown that the birds had a better intestinal health status, for example a higher villus to crypt ratio in the duodenum part of the small intestine.
LAYING HENS
Moreover, older animals like laying hens can also benefit from gut health additives. Genetic improvements have led to increased egg production and prolonged production cycles. Commercial egg producers have set new targets, reaching 500 eggs at 100 weeks of age. However, keeping flocks for such a long time is a challenge for most egg producers. As the hen ages, persistency of lay and eggshell quality tends to decline faster than desired. The gradual decrease in eggshell quality is partly due to the fact that the amount of mineral deposition remains almost constant during the production cycle while the egg weight increases slightly with the age of the hen and due to failure in the proper intestinal absorption of calcium. Hence products that could stimulate nutrient absorption and facilitate intestinal health are beneficial for improving layer persistence. A trial with Hisex® brown layers confirmed the benefit of supplementing 1kg/T of Butifour® CCB in a commercial diet. This trial started with laying hens of 55 weeks old and lasted for 4 periods of 30 days. During this trial different performance parameters were evaluated like egg production, egg mass and feed conversion ratio. It was shown that birds fed calcium butyrate had a 4 % increase in average laying rate during the 120 days period. Moreover, it was demonstrated that the control group decreased its initial laying rate after week 58, while butyrate was able to prolong the initial 90 % laying performance with 60 days. Thanks to the higher productivity of the laying hens, egg mass and feed conversion ratio was significantly improved during the trial period.
CONCLUSION
Concluding from the above-mentioned trials, a well-developed and functional gut is essential for animal performance across multiple species and ages. Nutrition plays a big factor in reaching a stable intestinal balance. Indeed, it can be source of different challenges but also of functional ingredients and feed additives with major impact on intestinal health. For example, organic acid blends or butyric acid sources are well known solutions to enhance or support the digestive system of livestock. Supplementing such additives together with an optimal feed formulation allows us to have an efficient and sustainable production of meat and eggs.
About Arno Duchateau
Arno Duchateau is a master in bioscience engineering who graduated in 2019 at the University of Leuven (Belgium). Since 2020, he worked as Global Product Manager in the specialty feed additives division at Impextraco focusing on gut health and mycotoxin solutions. Here, he provides technical support to business partners, customers and colleagues as well as managing different product brands from development to marketing and sales.
