Date of Award
Master of Science
AN ABSTRACT OF THE THESIS OF David Williams for the Master of Ruminant Nutrition degree in Animal Science, presented on December 12, 2016 at Southern Illinois University Carbondale. TITLE: IN VITRO APPARENT RUMINAL DIGESTIBILITY OF DIETS CONTAINING CORN DISTILLERS GRAIN WITH VARYING LEVELS OF CRUDE FAT MAJOR PROFESSOR: Dr. Rebecca Atkinson Four dual-flow continuous fermenters were used in a Latin square design to determine the apparent ruminal digestibility and ruminal characteristics of diets containing dried distillers grains plus solubles (DDGS) at various levels of fat content. Fermenters were randomly assigned to one of the following treatments: 1) 40% DDGS containing 4.82% fat content (40 LOW); 2) 40% DDGS plus corn oil to obtain 7.5% fat (40 MED); 3) 40% DDGS plus corn oil to obtain 10.5% fat (40 HIGH); or 4) 70% DDGS plus corn oil to obtain 7.5% fat (70 MED). Rumen fluid was collected at the beginning of each period from two ruminally cannulated Angus cows previously adapted to the 40LOW treatment. Each period consisted of 10 days with a seven day adaptation period followed by three days of sample collection. Calories per gram of diet increased as percent fat increased and calories per gram was greater at the 70% inclusion of DDGS compared to 40% inclusion of DDGS at all levels of fat content. However, level of fat in the diet did not influence (P ≥ 0.35) apparent ruminal digestibility of DM, NDF, ADF, CP or total calories. Similarly, inclusion rate of DDGS had no influence (P ≥ 0.35) on nutrient digestibility. Ammonia concentrations were greatest (P = 0.0002) for 70 MED compared to the other treatments. However, treatment had no impact (P ≥ 0.16) on volatile fatty acid production with the exception of propionate which increased (P =0.05) as the level of DDGS increased from 40 to 70% inclusion rate. This data would suggest that level of fat content of DDGS has no negative influence on apparent ruminal digestibility and select ruminal characteristics. From an economic perspective, higher fat DDGS should have a higher price differential, but lower fat DDGS can still be an effective protein and energy substitute.
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