Antibiotic-free animal production is a global issue. Consumers increasingly demand the elimination of this seemingly "traditional" form of production: it’s a health-conscious requirement of end customers around the world. Meanwhile, the feed industry is facing huge problems. Feed millers and farmers hope for a single additive that will solve all their problems. But the European experience shows a different reality: antibiotic-free production requires a combination of efforts.
There is no silver bullet for antibiotic elimination in animal feed; instead it requires efforts on multiple fronts. | Dr. Eckel Animal Nutrition
1. Improve hygiene of raw materials
Feed millers and farmers first must select adequate raw materials for a proper feed. Ingredients like rice bran, rice grit and rice polish may be highly contaminated with molds and yeast, and therefore with toxins. Their usage must be optimized in modern formulations. Mold inhibitors can reduce the mold; however, by the time those are applied, toxins such as mycotoxins or endotoxins have already been formed.
2. Optimize formulation
Modifying the formulation for a better feed (e.g., the most suitable protein and buffering capacity) is the second requirement for an optimal production. Modern formulations address most of the problems concerning the most suitable protein and the optimal use of the protein source and amino acids. The formulation is simulated in the corresponding software and approved in practice. However, diets often still include an excess of protein, producing a negative impact on performance and on the farm climate (e.g., ammonia).
The formulation of diets for young animal nutrition in particular needs more attention. Some of the ingredients are still underestimated. The effects of additives like specific acidifiers as well as optimal mineral and trace element usage (e.g. magnesium oxide, limestone or zinc oxide have a high buffering capacity with a negative impact on digestion) are essential. Further, we should also use modern phytases to reduce the mineral content of the diet and anti-nutritive effects of the ingredients.
Formulation of an ideal feed will positively influence the upcoming animal welfare discussion. For instance, reducing ammonia will lead to reduced respiratory diseases, and increased litter quality to better general animal health.
Additives, such as acidifiers, minerals and trace elements (e.g. magnesium oxide, limestone or zinc oxide) that have a high buffering capacity with a negative impact on digestion, are essential to digestion. | Dr. Eckel Animal Nutrition
3. Manage and optimize nutrient intake
Managing feed and nutrient intake is the most critical challenge for nutritionists, due to the specific pressure they are subjected to. As most antibiotic growth promoters (AGPs) have activity against primarily gram-positive bacteria, AGP alternatives that target gram-positive bacteria (with minimal risk of resistance) with established and advantageous sub-inhibitory effects and some appropriate immunomodulatory properties may provide the best candidates to pursue further.
Immunomodulation shifts interest to inflammation. Inflammatory responses result in a series of biochemical, physiological and behavioral changes that impact nutrient intake and absorption with a consequent decrease in profitability and productivity. The most important influence of an immune response is the reduction in feed intake followed by a decrease in the digestion of nutrients (mainly fat and some amino acids). Reduction in feed intake represents 68 percent of decreased growth due to E. coli.
Besides the indisputable immunoregulators (e.g. vitamin E), we also find non-essential phytonutrients that can modulate immunity.
The effect of a flavonoid-rich phytonutrient product on piglets was investigated in a recent study. One result was an increased villus height to crypt depth ratio in the small intestine due to feeding. The research group assumed that an increased villus height leads to an improvement in the digestive and absorptive functions of the intestine, which seems to be caused by an increased absorptive surface, expression of brush border enzymes and nutrient transport systems. They concluded that oral administration of a polyphenol-rich phytonutrient suppresses the activity of NF-κB in the small intestine of pigs. This may provide a useful dietary strategy to inhibit inflammation in the gut. Other research gives reason to believe that similar effects can be assumed in chickens as well as aquatic species.
While other factors can contribute to growth depression, studies show a 68 percent reduction in broiler chick feed intake due to E. coli. | Klasing, 2017
A further issue besides that of feed intake and digestive inefficiencies is the effect on nutrient digestibility. Research has shown the interesting effect on ileal digestibility of select nutrients after intravenously infecting broiler chicks with E. coli. In summary, the results seem to show that methionine, lipid, retinol, lutein, calcium and iron digestibility in particular are negatively affected. Digestibility is decreased by up to 37 percent.
Conclusion and outlook
Farmers and feed millers are presented with different issues on their way to antibiotic-free animal nutrition. Besides the selection of raw materials (the cheapest is not the most cost effective), we should optimize and fine tune our formulations to obtain the best result possible. This point will gain even more interest in the future due to the upcoming animal welfare discussion, e.g. food pad lesion, ammonia and respiratory challenges.
Nevertheless, one of our biggest challenges will be addressing inflammation and managing its effect on feed intake, performance and animal health.
References available upon request