Twelve neonatal Holstein bull calves (38.52 ± 5.87 kg) were fed milk replacer at a fixed or varied meal time to determine the effects on metabolic hormone secretion, average daily intake, growth, and energy metabolism. Body weights were measured every two weeks from birth to 8 weeks. Rumen fluid was collected every two weeks from week 2 through 8. Serial blood collections were conducted every two weeks from week 2 through 8. Blood was collected, beginning at 0530, at 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 minutes. Plasma was analyzed for ghrelin, leptin, growth hormone (GH), and insulin-like growth factor-1 (IGF-1). Treatment did not affect body weight or average daily intake. Mean plasma ghrelin, leptin, GH, and IGF-1 concentrations were not affected by treatment. A treatment by week interaction was observed for plasma ghrelin concentrations. Plasma ghrelin concentrations were higher at weeks 2 and 4 in control calves. Plasma ghrelin concentrations decreased in all calves as they aged. A treatment by time interaction was observed for IGF-1, and a treatment by week by time interaction was observed for growth hormone and IGF-1. Growth hormone decreased as calves aged, while IGF-1 increased. There was no treatment effect or interactions of treatment and week on butyrate and propionate concentrations. However, both butyrate and propionate increased with age. Treatment and week effects were present for acetate, as well as a treatment by week interaction. Calves in the control group had a higher percentage of acetate. Acetate concentration increased in all calves as they aged. At weeks 4 and 8, intravenous glucose tolerance tests were performed to assess glucose clearance. A treatment effect was observed for glucose half life (T1/2), glucose clearance rate (k), and insulin. Glucose half- life was higher for calves in the control group, while the clearance rate was lower for the control group. Peak insulin concentrations were higher for calves in the treatment group. It is concluded that feeding time does not affect overall growth and feed intake, but does have an affect on the some of the regulatory mechanisms that control them.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-06242010-091330 |
| Date | 29 June 2010 |
| Creators | Simon, Katherine Claire |
| Contributors | Williams, Cathleen, Jenny, Bruce, Thompson, Donald |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-06242010-091330/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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