Three experiments were conducted to determine the efficacy of an <i>Escherichia coli</i> 6-phytase (Quantum phytase) in laying hens fed corn-soybean meal based diets. In experiment 1, the Escherichia coli 6-phytase (Quantum) was evaluated for its efficacy in a 40-wk laying hen production trial. A total of 1080 White Leghorn hens were fed mash corn-soybean meal (CSM) based diets containing 0.35%, 0.25% or 0.15% of non-phytate phosphorus (NPP) with the 0.25% and 0.15% diets containing 200, 400 and 600 U/kg of exogenous phytase. Only minor differences in production characteristics were found between the 0.35% and 0.25% treatments regardless of phytase addition, indicating that 0.25% NPP resulted in P intake that was at or above the hens requirement. In contrast, the hens fed the 0.15% NPP diet without phytase supplementation had significantly reduced production performance in comparison to the 0.35% treatment. The addition of phytase to the 0.15% diet improved these production characteristics to levels equal to or better than the 0.35% diet. The results indicated that Quantum phytase was efficacious in CSM-based diets fed to White Leghorn laying hens and can be used to reduce the need for diet supplementation with inorganic phosphorus.
In experiment 2, the effect of Quantum phytase on nutrient digestibility and bone ash in laying hens fed CSM-based diets was investigated. A total of 108 White Leghorn hens were fed CSM-based diets containing 0.35%, 0.25% or 0.15% NPP with the 0.25% and 0.15% diets containing 200, 400 or 600 U/kg of exogenous phytase. A linear reduction in phytate digestibility, ileal protein digestibility and soluble P was reported with increasing levels of exogenous phytase in the 0.25% diet. Tibial bone ash percentage was higher in 61-wk-old hens fed 0.25% diets supplemented with 200 or 400 U/kg phytase. Overall, the Quantum phytase was not efficacious in improving nutrient digestibility in laying hens fed CSM-based diets deficient in NPP.
In experiment 3, the impact of dietary Ca and P level on the efficacy of an E. coli-derived 6-phytase and the apparent digestibility of various nutrients was investigated in White Leghorn laying hens fed CSM-based diets. A total of 384 White Leghorn hens were fed CSM-based diets containing four levels of Ca (2.5, 3.5, 4.5 or 5.5%), two levels of NPP (0.15 or 0.30%), and two levels of phytase (300 or 600 U/kg feed). Increasing dietary Ca caused a decrease in AMEn, duodenal protein digestibility, Ca and phytate digestibility, percentage soluble P in feces and the percentage of poor quality eggs, while significantly increasing bone ash and hen-housed and hen-day egg production. The higher level of NPP (0.30%) decreased AMEn, fecal protein, Ca and P digestibility, and hen-housed and hen-day egg production, while increasing fecal soluble P and egg specific gravity in comparison to the lower NPP level. The higher level of dietary phytase (600 U/kg feed) significantly increased AMEn, phytate and P digestibility, soluble P in feces, and hen-day and hen-housed egg production, while significantly reducing the percentage of soft shelled, cracked and broken eggs. Overall, dietary phytase, Ca and NPP levels, either as main effects or in an interactive manner, can affect apparent nutrient digestibility and production traits in laying hens fed CSM-based diets.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-01172009-103855 |
| Date | 22 January 2009 |
| Creators | Beutler, Amanda Lynn |
| Contributors | Classen, Henry L. (Hank) |
| 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-01172009-103855/ |
| 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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