"An important nutritional outcome is how well an animal is able to digest and metabolize its diet," said Ryan Dilger.
Poultry and swine nutritionists are concerned about dietary fiber in alternative dietary ingredients, particularly the by-products of biofuel production. Fiber concentrations are very high in these ingredients because the starch content is removed during processing.
Dilger and his master's student Emma Wils-Plotz looked at how purified fiber fed to young chicks affects their dietary threonine (Thr) requirements, intestinal morphology, and ability to resist a disease challenge. Threonine is an essential amino acid accounting for as much as 11 percent of mucin, an important component of the mucus layer covering the intestine's absorptive surface, which promotes gut health by protecting the body against bacteria and digestive enzymes.
Previous research has suggested that mucin dynamics may be sensitive to Thr availability. Dilger and Wils-Plotz hypothesized that dietary Thr requirements would increase in the presence of two purified fiber sources, cellulose and pectin, which are natural components of many feed ingredients.
They fed diets containing purified cellulose, pectin, or silica sand (control) to chicks and found that body weight gain and feed efficiency (the conversion of feed into body-weight gain) were reduced when 7 percent supplemental pectin was added to the diet. Pectin creates a viscous environment in the gut that interfered with the birds' ability to access dietary nutrients, thus reducing growth performance. Feeding 7 percent purified cellulose did not provide any nutritional benefit.
In a second experiment, Wils-Plotz and Dilger quantified the dietary threonine requirement in the presence and absence of purified fiber sources. Chicks were fed one of the three fiber-containing diets. Within each diet, they were subdivided into seven groups, each fed a different level of Thr supplementation ranging from 0 to 9.6 grams per kilogram (g/kg). Contrary to the researchers' expectations, birds fed the diet with pectin had the lowest Thr requirements at 5.6 g/kg; birds fed the control diet had the highest, estimated to be 6.8 g/kg. Cellulose-fed birds required 5.8 g/kg.
Ileal tissue, which is at the end of the small intestine, was collected from chicks and examined for physical changes in the villi (small folds in the intestine), crypts (pockets next to the villi), and goblet cells, which produce and secrete mucin. Chicks fed cellulose or pectin had deeper crypts than chicks fed the control diet; crypts were deepest for birds fed cellulose and adequate Thr levels, and their outer intestinal muscle layer (serosa) was thicker. Chicks fed diets containing fiber had higher goblet cell counts than the birds fed the control diet, with highest levels in birds fed the pectin diet with adequate or high Thr levels.
The findings suggest that dietary Thr concentration and fiber source affect growth performance, intestinal morphology, and mucin secretion in young chicks. It also established optimal dietary Thr levels.
Having determined these levels, the researchers wanted to see if fiber and Thr in the diet could affect how chicks responded to a coccidiosis challenge. Coccidiosis is a parasitical disease of the intestinal tract caused by protozoa of the genus Eimeria maxima, which is responsible for major economic losses in the poultry industry.
"Right now, there are few advancements in coccidiosis vaccine development, so we tried to develop dietary approaches to assist the bird through a coccidiosis challenge," Dilger said. "Our hypothesis was that by providing adequate threonine, the bird would have better immune defenses through improved gut function and immunity."
Chicks received either a diet supplemented with pectin or a Thr-deficient control diet and either 75 percent or 125 percent of the previously determined optimal Thr supplement of 6.8 g/kg. Within each dietary treatment, one group of chicks was inoculated with E. maxima; the other was not.
"The goal was to determine the interaction between dietary fiber and dietary threonine, knowing that pectin was going to negatively affect digestion and threonine was going to positively affect intestinal health," Dilger explained.
Growth and feed efficiency were monitored for 16 days; then ileal tissue, mucosal scrapings, and the ceca (the part of the digestive tract used for water absorption and fermentation) were collected. Researchers looked at growth performance, morphological changes in the intestine, changes in the cecal environment, and gene expression in the ceca and mucosa.
"The most important part of the story was the cytokine response to the acute coccidiosis infection," Dilger said.
Cytokines regulate how the immune system communicates with the rest of the body and adjust the immune response. Interleukin-12 (IL-12) expression in the ceca was increased in birds fed the control diet with high threonine. Interleukin-1 beta expression increased with infection but only in birds fed the low-Thr diet.
Expression of interferon gamma (IFNG), a protein made and released in response to the presence of pathogens, increased in the ileal mucosa of birds fed high Thr, and was highest in the uninfected chicks. It increased with infection but only in control-fed birds
The researchers concluded that while pectin had some protective effects against coccidiosis infection, Thr supplementation had an even greater influence on the intestinal immune response and helped to maintain growth of chicks infected with coccidiosis. This study and others being conducted in Dilger's lab highlight the potential for using nutritional strategies to manage poultry and swine diseases.
The research is described in more detail in "Effect of fiber and threonine on chick growth" by E. L. Wils-Plotz and R. N. Dilger and "Modulation of the intestinal environment, innate immune response, and barrier function by dietary threonine and purified fiber during a coccidiosis challenge in broiler chicks" by E. L. Wils-Plotz, M. C. Jenkins, and R. N. Dilger, both in the March 1, 2013, issue of Poultry Science (http://ps.fass.org/content/vol92/issue3/index.dtl?etoc).
Susan Jongeneel | EurekAlert!
Farming with forests
23.09.2016 | University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)
Ecological intensification of agriculture
09.09.2016 | Julius-Maximilians-Universität Würzburg
Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.
Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...
Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.
Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
30.09.2016 | Event News
29.09.2016 | Event News
28.09.2016 | Event News
30.09.2016 | Materials Sciences
30.09.2016 | Earth Sciences
30.09.2016 | Life Sciences