Two trials were conducted to evaluate effects of grain adaptation protocol on subacute acidosis, feeding behaviour and ADG of cattle. In trial one, 12 crossbred heifers (384 ¡À 25 kg) were stepped from 40% to 90% dietary concentrate by either rapid adaptation (RA; one step-up diet fed for 3 d) or by gradual adaptation (GA; five step-up diets fed for 3 d each). Mean daily ruminal pH variables did not differ (P > 0.10) between treatments but variances of a number of ruminal pH variables were greater (P < 0.05) for RA than GA during adaptation to 65% and 90% concentrate. Mean hourly pH did not differ over the first 24 h of adaptation to 65% concentrate, but variance of hourly pH tended (P < 0.10) to be greater for RA than GA for eight of the first 24 h of adaptation to 90% concentrate. Increased variance in ruminal pH parameters was associated with detection of acidosis in certain individuals. On d 1 of 90% concentrate, ruminal pH tended (P = 0.07) to be lower at 11 and 12 h post-feeding with RA than with GA. Ruminal volatile fatty acids (VFA) and osmolality were similar between treatments. In trial two, 120 crossbred heifers (366 ¡À 23 kg) were adapted from 40% to 90% concentrate. A protocol identical to trial one was used with the addition of moderate adaptation (MA; three step-up diets fed for 3 d each). The increase to 65% concentrate caused reduced daily bunk attendance and increased maximum intermeal interval for RA compared to MA and GA cattle but the increase to 90% did not. ADG was reduced for RA compared to MA or GA during adaptation but over day 1 to 69 ADG did not differ between treatments (P ¡Ý 0.41). Current management strategies for preventing acidosis in pens of cattle are based on responses of the most susceptible individuals. Improved understanding of individual responses to acidotic challenge may allow development of more effective acidosis prevention practices.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-03102005-190050 |
| Date | 13 April 2005 |
| Creators | Bevans, Darren Wayne |
| Contributors | Van Kessel, Andrew G., McKinnon, John J., McAllister, Timothy, Buchanan, Fiona C. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-03102005-190050/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto 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 University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, 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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