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The effects of level of forage on rumen metabolism of feedlot cattle fed corn or DDGS-based diets

Research Scholar

Janaina Dolci Polonio, OARDC - Animal Sciences (Brazil)
Steven Loerch, Faculty Mentor

Biography

Janaina Dolci Polonio is from Ourinhos, Brazil. In 2007, she began her animal sciences undergraduate program at São Paulo State University (UNESP). As an undergraduate, she participated in two research internships dealing with animal welfare and meat quality. In 2010, Polonio published three articles in the annual report of the Brazilian Animal Science Society that dealt with cattle welfare and carcass lesions. Currently, she is working in ruminant nutrition with Dr. Steven Loerch at the Ohio Agricultural Research and Development Center (OARDC) in Wooster, Ohio.

What is the issue or problem addressed in your research?

Distillers grains (DDGS) is a byproduct of the ethanol industry. Feeding DDGS to cattle improves growth and reduces costs when it replaces corn at less than 20% of the diet because DDGS is cheaper than corn and yet is similar in energy content. However, reductions in feed intake and growth are noted in cattle fed more than 20% DDGS (Klopfenstein et al., 2008). The reason for this is not well understood but may be due to sulfuric acid that is added to control pH during fermentation. The sulfuric acid that is added to the corn grain during distillation, remains in the byproduct, contributes to dietary sulfur, and makes the diet acidic. Recent discoveries at The Ohio State University have revealed that sulfuric acid present in the DDGS may cause a metabolic disease in cattle called acidosis in addition to contributing to the high sulfur content. Adding forage to increase rumen pH may reduce sulfur toxicosis and acidosis. Feeding higher inclusions of DDGS to cattle would be economically advantageous because DDGS is cheaper than corn. The objective of this research is to determine the effects of level of forage on rumen sulfur metabolism and rumen pH in cattle fed corn or DDGS-based diets. We hypothesize that added dietary forage (to attenuate low rumen pH) may be more important with DDGS-based diets than corn-based diets. Previous work has shown that reduced rumen pH is associated with increased H2S gas production, which causes sulfur toxicosis.

What methodology did you use in your research?

Eight ruminally fistulated heifers will be used. Treatments investigated are: 1) 60% DDGS with 7% hay supplementation, 2) 60% DDGS with 14% hay supplementation 3) 78% cracked corn with 7% hay supplementation, and 4) 71% cracked corn with 14% hay supplementation. Two heifers will be assigned one of the 4 diets, in each of 4 periods (17 d) , such that each heifer will receive all diets.

On d17 of the period, rumen samples will be taken at 0, 1.5, 3, 6, 9, and 12 hr for hydrogen sulfide gas (H2S), liquid sulfide (S2-), and pH determination. The H2S gas will be measured via hydrogen sulfide precision gas detector tubes. A dual meter will be used to measure pH and S2- on rumen liquid samples. Feed intake will be measured daily.

What are the purpose/rationale and implications of your research?

Our hypothesis is that adding dietary forage will alleviate acidosis and reduce hydrogen sulfide gas production in the rumen. If this is true, DDGS could be fed at higher inclusions to cattle; which would be economically advantageous.