The impact of lactate producing direct-fed microbial (DFM) on growth performance and rumen fermentation in beef cattle was explored in four studies. Experiment 1 studied the interaction between DFM and degradable intake protein (DIP) supply in receiving cattle. No differences (P≥0.06) in intake, morbidity, or immune response were observed; however, during the first 28 d gain and efficiency responses to DFM were dependent on DIP (DIP×DFM P≤0.05). Experiment 2 showed that in vitro gas production and select endpoint metabolites differed (P≤0.04) with DFM application. Experiment 3 compared lactate producing DFM to a lactate producing/utilizing DFM in finishing cattle. No differences (P≥0.14) in intake, gain, efficiency, or carcass characteristics were observed between control and lactate DFM; however, gain and growth efficiency differed (P≤0.05) between the lactate producing and lactate producing/utilizing DFM during the later portions of feeding. Experiment 4 studied the impact of DFM on ruminal fermentation, lactate utilization, and total tract digestibility. Ruminal pH and molar proportions of acetate were increased (P≤0.05) with DFM; however, lactate utilization and total tract digestibility did not differ (P≥0.33). The studies suggest that DFM improve growth performance during receiving and responses are at least partly mediated through differences in ruminal fermentation.
| Identifer | oai:union.ndltd.org:uky.edu/oai:uknowledge.uky.edu:animalsci_etds-1016 |
| Date | 01 January 2013 |
| Creators | Kenney, Nicole |
| Publisher | UKnowledge |
| Source Sets | University of Kentucky |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations--Animal and Food Sciences |
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