Animal Science, Department of


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Marco G. Dib A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science Major: Animal Science Under the Supervision of Professors Galen E. Erickson and Terry J. Klopfenstein Lincoln, Nebraska November, 2010


A cattle finishing experiment was conducted to evaluate effects of intermittent feeding of Optaflexx compared to none or continuous feeding. Four treatments were evaluated, the negative control consisted of 63 days on the same diet without Optaflexx, wherea the positive control consisted of Optaflexx supplemented daily during the last 35 days before harvest. The 4-day intermittent treatment consisted of feeding Optaflexx for7 days, followed by 4 days of no Optaflexx, and the 7-day intermittent treatment 7 d on Optaflexx, followed by 7 days off. Regardless of the delivery pattern, feeding Optaflexx increased ADG, DMI, and live BW compared to negative control. Feeding 200 mg per steer daily of Optaflexx for a total of 35 days in either 4-day or 7-day intermittent patterns was as effective as continuous feeding.

A study was conducted to estimate genetic parameters for weights and heights of mature cows using a repeatability model from field data provided by the American Angus

Association. The results show that the heritability of both traits is large and correlations between them are positive and strong. Results suggest that either trait would response favorably to selection and changing one would lead to a correlated response in the other.

A feedlot cattle finishing experiment and two 39-day metabolism trials were conducted using a combination of modified distillers grains and wet corn gluten feed to adapt beef cattle to finishing diets. During adaptation, DMI tended to be greater for traditional adaptation with forage compared to the co-product blend during the first period, but not different in subsequent periods. Average ruminal pH was lower for the co-product blend on step 1 and 2 compared to forage in Exp. 1 with no difference observed in Exp. 2. No difference in ruminal pH was observed between treatments for step 3 and 4. Significant difference was observed for DM digestibility between treatments during step

1 with higher values for the co-product treatment. Results from the feedlot experiment were not significantly different between treatments. Results indicate that a combination of MDGS and WCGF may be a viable method to adapt beef cattle to finishing high-concentrate diets for feedlots.