A series of experiments were conducted to examine protein digestion in the young bird and the physiological changes that affect protein digestion as the bird matures. Trial one determined the effect of age on pH of the gastrointestinal tract. The results showed that the pH of the proventriculus and gizzard decreases with age suggesting that gastric acid secretion increases proportionally with age and this may impact protein digestion. Experiment two examined the effect of age on ileal amino acid (AA) digestibility of feed ingredients. AA digestibility increased from 5 to 21 d and the degree of improvement differed among ingredients and specific AA. This finding coupled with the low AA content of some ingredients demonstrates the importance of using appropriate nutrient digestibility values for young birds when formulating pre-starter and starter diets. Experiment three determined the acid binding capacity (ABC) of feed ingredients and the effect of formulating diets based on ABC on diet ABC, gastrointestinal pH and performance. The research confirmed dramatic differences in ABC among ingredients and that diets could be formulated on the basis of ingredient ABC. However, the range in diet ABC was less than predicted suggesting interactive effects among ingredients. Intestinal pH was reduced however broiler performance was not improved when diets low in ABC were fed. Experiment four examined the effect of diet acidification with HCl on diet ABC, gastrointestinal pH, ileal amino acid digestibility and broiler performance. Improvements in performance and reductions in mortality were observed when broilers were fed acidified diets. Adding acid to diets did not improve AA digestibility and therefore was not the reason for improved performance indicating an alternative mechanism of action. It is concluded that acid production by the proventriculus of young birds is low and increases with age however this does not impact protein digestion. Methods of improving performance of broiler chickens may include diet acidification however this is not the effect of remedying the low acid production by young birds. Therefore, alternative mechanisms are positively affecting broiler performance.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-09182009-184057 |
| Date | 30 September 2009 |
| Creators | Rynsburger, Joni Maria |
| Contributors | Korver, D., Hamilton, D., Laarveld, B., Drew, M., Classen, H.L. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-09182009-184057/ |
| 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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