Two experiments were conducted to determine the efficacy of supplemented feedstuffs to improve the performance of cattle consuming fescue-based rations. The objective of the first experiment was to evaluate growth and reproductive characteristics of heifers consuming endophyte-infected (EI) fescue seed with or without sodium bicarbonate supplementation. Forty-eight heifers (8 mo; BW = 268 ± 24 kg) were utilized in a 2 x 2 factorial design. Treatments were either high-EI fescue seed without sodium bicarbonate (E+B-), high-EI fescue seed with sodium bicarbonate supplementation (E+B+), low-EI fescue seed without sodium bicarbonate (E-B-), or low-EI fescue seed with sodium bicarbonate supplementation (E-B+). At d 56, G:F (P= 0.084) and ADG (P = 0.071) tended to be improved for heifers fed E+B+. By d 84 bicarbonate supplementation tended to decrease ADG (P = 0.087). Bicarbonate supplementation ameliorated the negative effects of E+ at 28 d, but by d 84 negatively impacted animal performance. The objective of the second experiment was to determine the energy content of corn gluten feed (CGF) relative to corn in forage-based beef rations. Forty-two steers (13.8 ± 0.4 mo; BW = 382 ± 8 kg) were supplemented with either corn or CGF at 0.15% (L), 0.54% (M) or 0.96% (H) BW for 63 d. Steer ADG was greater for steers supplemented with CGF relative to steers supplemented with corn (P = 0.034). Energy value of CGF relative to corn was calculated by adjusting supplement TDN in the 2016 Nutrient Requirements of Beef Cattle Model. The energy values of CGF relative to corn were 106%, 107%, and 112% for L, M, and H. / Master of Science / Tall fescue is the predominant forage in the southeast United States, and has a symbiotic relationship with an endophytic fungus, providing drought and pest resistance to the plant. However, the fungal endophytes produce toxic ergot alkaloids which can result in decreased performance when cattle consume tall fescue. Performance losses, resulting from the consumption of these ergot alkaloids, are costly and economical strategies to reduce the negative impact of endophyte-infected fescue consumption on animal performance are needed. Previous research indicates that ruminal buffering capacity and nutrient uptake may be impaired in cattle consuming endophyte-infected fescue seed. Providing a dietary buffer is a low-cost strategy that my help to improve nutrient utilization in cattle, resulting in improved animal performance. Aside from reduced performance resulting from the consumption of ergot alkaloids, forage nutrient content can vary throughout the year, resulting in situations where the animals’ nutrient requirements are not met by the forage alone. Historically, corn has been the major energy supplement used, but recent data suggest that co-products of the corn sweetener and ethanol industries have greater energy compared to corn in both feedlot and forage-based beef rations. Supplementing corn gluten feed at low levels may improve performance of cattle consuming forage-based rations without driving up the cost of production. The objective of this thesis is to evaluate two strategies to mitigate the negative effects of endophyte-infected fescue consumption on animal performance. The first experiment was conducted to evaluate the efficacy of sodium bicarbonate to mitigate the negative effects of endophyte-infected fescue on replacement heifers. Heifers were fed a basal corn silage diet. Fescue seed and bicarbonate were supplemented at 1.5 kg/day and 0.25 kg/day, respectively. After a 56 d treatment period, bicarbonate supplementation tended to improve performance of heifers fed endophyte-infected seed with bicarbonate relative to those fed un-infected seed without bicarbonate supplementation. However, by d 84 of the experiment, the benefits of bicarbonate supplementation were no longer observed. More research is needed to understand why the benefits of sodium bicarbonate supplementation were not sustained over the full experimental period. The second experiment was conducted to evaluate the feeding value of corn gluten feed relative to corn when fed to steers consuming a forage-based ration. Steers had free-choice access to fescue hay, and individual hay and supplement intake were recorded daily. Steers supplemented with corn gluten feed had greater average daily gain than steers supplemented corn. This translated to a greater energy value relative to corn for all inclusion levels, exceeding model predictions. These experiments help to shed light on low-cost solutions to improve performance and profitability for fescue forage-based beef production systems.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/83500 |
| Date | 08 June 2018 |
| Creators | Hardin, Keri Nicole |
| Contributors | Animal and Poultry Sciences, Wilson, Thomas Bain, Greiner, Scott P., White, Robin R. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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