Effects of adding dried distillers grains with solubles (DDGS) to dog diets supplemented with xylanase and protease

This study aimed to evaluate the effects of including 200 g kg(-1) dried distillers grains with solubles (DDGS) to xylanase- and protease-supplemented diets for dogs on kibble properties, digestibility, fecal characteristics, and palatability. Experimental diets consisted of: 0 g kg(-1) DDGS without enzymes (0WE), 0 g kg(-1) DDGS with xylanase and protease (0XP), 200 g kg(-1) DDGS without enzymes (200WE), 200 g kg(-1) DDGS with xylanase (200X), 200 g kg(-1) DDGS with protease (200P), and 200 g kg(-1) DDGS with xylanase and protease (200XP). Kibbles were evaluated for density, extruded size, expansion index, hardness, and uniformity. Six beagle dogs were distributed in a 6x6 Latin square design for analysis of digestibility and fecal characteristics. A palatability assay was also conducted in 16 beagle dogs, comparing the following treatment groups: 0WE vs. 200WE and 0XP vs. 200XP. The results showed that DDGS inclusion had no influence on kibble physical properties and reduced digestibility of dry matter (DM), ether extract after acid hydrolysis, gross energy, and organic matter, regardless of enzyme addition. Moreover, dietary addition of DDGS reduced fecal pH and increased total short-chain fatty acid, acetate, and propionate productions. Fecal odor was increased in dogs fed diets containing DDGS. Regarding palatability, animals preferred diets supplemented with enzymes and without DDGS, and no difference was observed when comparing 0WE and 200WE diets. No changes in the physical properties of kibbles were caused by DDGS inclusion; therefore, it can be used in diet formulation without interfering with the industrial process. Increased production of SCFA and a possible modulation of digestive tract microbiota promoted by DDGS addition may benefit animals. However, at the tested levels, enzymes had no positive effects on diet digestibility. Despite reducing digestibility, DDGS can still be included without enzyme supplementation in low-cost diets for dogs, as nutrient digestibility of the diet remains within acceptable limits for some pet food categories.