Effect of Low-Fat Dried Distillers Grains Inclusion in Finishing Diets on Feedlot Cattle Total Tract Digestibility and Ruminal Fermentation Parameters

Beef

Executive Summary

High dietary fat levels are known to suppress ruminal fiber and total tract organic matter digestion due to the toxic effects on growth of ruminal microbes; cellulolytic bacteria and protozoa being the most sensitive ones. Decreased cellulolytic activity due to high dietary fat decreases rates of fiber digestion and particle size reduction. These effects interact to increase ruminal solids retention time, which effects a reduction in intake and overall feedlot performance. Therefore, low fat content of low-fat distillers grains could attenuate negative effect sof high dietary fat on ruminal fermentation, support improved rumen function, and subsequently enhance overall nutrient digestibility, feed intake and utilization, and feedlot cattle performance. In addition, reduced sulfur concentration in low-fat distillers grains as a result of less CDS added back to the distillers fraction may permit increased inclusion of this new product in feedlot diets.

These data demonstrated that LF-DDGS are an appropriate substitute for both corn and conventional DDGS in diets of feedlot cattle. These data support our observations that inclusion of LF-DDGS or conventional DDGS at 35% of diet dry matter sustain growth and efficiency at equal rate as corn-based diets.

To date, however, little data are available on the feeding value of low-fat distillers grains. A previous study conducted with feedlot heifers by Kansas State University evaluated feeding steam-flaked corn diets containing 13% DM traditional distillers grains plus solubles or low-fat DDG and no treatment differences in feedlot performance or carcass characteristics. Similar results were observed in a previously funded MCG—AURI study at the University of Minnesota where feeding dry-rolled corn (DRC)-based finishing diets containing 35% DM traditional or low-fat DDG to finishing steers caused no differences in feedlot performance or carcass characteristics. On the other hand, inclusion of 35% DM traditional WDGS to DRC- or high-moisture corn-based finishing diets resulted in greater final BW, average daily gain (ADG) and hot-carcass weight compared with low-fat WDGS inclusion. Lower fat concentration and consequently reduced energy value of low-fat distillers grains compared with traditional DGS may account for the latter results.

Therefore, basic fermentation research is warranted to determine effects of low-fat distillers grains inclusion in finishing diets on ruminal fermentation and feed digestibility and to allow for a better understanding of its potential effects on feedlot cattle performance. This information may assist in creating feeding recommendations to best utilize this new product as a feedstuff in feedlots throughout the Midwest. The objective of this research was to evaluate the effect of low-fat dried distillers grains with solubles (LF-DDGS) on organic matter (OM) total tract digestibility and ruminal fermentation parameters. Inclusion of LF-DDGS resulted in lower NH3-N concentration and increased ruminal VFA compared with traditional DDGS which may be the consequence of enhanced growth of ruminal microorganisms as a result of reduced dietary fat. Partial replacement of DRC by LF-DDGS, and its potential effects on growth of ruminal microbes and NH3-N utilization, led to no change in NH3-N or VFA while that by conventional DDGS led to increased NH3-N concentration and decreased ruminal VFA concentration. These data demonstrated that LF-DDGS are an appropriate substitute for both corn and conventional DDGS in diets of feedlot cattle. These data support our observations that inclusion of LF-DDGS or conventional DDGS at 35% of diet dry matter sustain growth and efficiency at equal rate as corn-based diets. There is no reason to alter the price of LF-DDGS relative to conventional DDGS when including this new alternative in diets of feedlot cattle.

Effect of low-fat dried distllers grains inclusion in finishing diets on feedlot cattle total tract digestibility and ruminal fermentation parameters

By I. Ceconi, A. DiCostanzo, and G. I. Crawford. University of Minnesota, Saint Paul.