By Joel DeRouchey, Madie Wensley, Mike Tokach, Jason Woodworth, Bob Goodband and Jordan Gebhardt of Kansas State University
Post-weaning diarrhea (PWD) is generally defined as loose, watery stool occurring in the first 14 days after weaning. The incidence of PWD is multi-faceted, but often results from exposure to infectious pathogens such as rotavirus, Salmonella or Escherichia coli (E. coli). Sensitivity to PWD is also affected by physiological and metabolic changes of the gastrointestinal (GI) system that occur at the time of weaning, leaving the newly weaned pig more vulnerable to enteric disease outbreaks. Here are four ways nutrition can help.
Dietary zinc and copper
To prevent pathogen induced diarrhea in weanling pigs, pharmacological levels of zinc (2,000 to 3,000 ppm) from zinc oxide (ZnO) are commonly fed for the first 2 to 3 weeks after weaning. The mode of action of ZnO is not well understood; however, several different mechanisms related to immune system modulation, nutrient absorption and preservation of intestinal morphology have been identified. Copper is another mineral that can be fed to prevent pathogen induced diarrhea. However, pharmacological levels of copper (125 to 250 ppm) from copper sulfate or tribasic copper chloride generally aren’t fed until late nursery. Unfortunately, these feeding practices have led to increased environmental concerns and issues surrounding bacterial resistance. This emphasizes the need to evaluate alternative feeding strategies for the prevention and management of enteric disease, specifically E. coli.
Low crude protein, AA supplemented diet
When feeding a standard 21% to 23% crude protein diet, a percentage of undigested protein will enter the large intestine, leading to increased microbial fermentation and the production of diarrhetic compounds such as ammonia and amines. This response is often exacerbated if pigs are exposed to pathogens, particularly when ZnO is removed from the diet. Hence, feeding low CP diets during the first 7 to 14 days after weaning is an important strategy that can be used to decrease the amount of protein entering the large intestine for fermentation. This can be accomplished by increasing the concentrations of feed grade amino acids, reducing the dietary digestible lysine level below the optimal performance requirement, and using highly digestible amino acid sources.
Fiber use
Fiber has prebiotic properties that are thought to stimulate the proliferation of good bacteria, such as bifidobacteria, lactobacilli and eubacteria. Soluble fibers increase intestinal viscosity, which have been shown to decrease digesta passage rates and subsequent proliferation of pathogenic E.coli. Conversely, insoluble fibers have a relatively low fermentation capacity, decreased intestinal viscosity and increased digest passage, which have been shown to increase fecal bulk. Because of this, insoluble fiber sources that are high in cellulose, such as oat hulls and wheat bran, are used in starter diets to promote GI health.
Low acid binding capacity diets
binding capacity is defined as the amount of acid required to produce a unit change in pH of a complete feed or ingredient. Some ingredients such as minerals (i.e., ZnO and limestone) have a higher value compared to cereal grains, and therefore bind acid more readily. The manipulation of stomach acidity can be achieved through diet formulation strategies to decrease complete feed ABC values, including the reduction of minerals such as calcium and phosphorus or the addition of organic acids to the diet. Both have shown positive effects on pig growth performance and feed efficiency. In addition to decreasing gastric pH, some organic acids including butyric, formic, acetic and propionic also have bacteriostatic properties that act directly on gram negative bacteria cell walls to slow down pathogen metabolism and subsequent proliferation.
Read more in our newly published AASV Practice Tip.
