|Full text PDF:||http://digitool.library.mcgill.ca/thesisfile141568.pdf|
Two experiments were conducted to evaluate the effects of 2 extruded flaxseed meals (EF1 and EF2; flaxseed:alfalfa 4:1) on n-3 fatty acids deposition in eggs, egg production parameters, egg components (i.e. yolk, albumen and eggshell percentages) and cholesterol concentrations, and apparent total tract nutrient digestibility of laying hens. Moreover, in Experiment 2, birds were euthanized for measurements of blood plasma and liver fatty acid concentrations. Seventy two layers were randomly allotted to 1 of 4 dietary treatments (6 cage replicates; 3 hens/cage) and raised over an 8-week experimental period. Dietary treatments included a standard corn-soybean meal diet containing 0%, 7.5%, 15% and 22.5% EF1 for Experiment 1, and 0%, 3%, 6%, and 9% EF2 for Experiment 2.In Experiment 1, feeding layers with EF1 up to 22.5% of the diet had no effect on feed intake, egg production and feed conversion ratio. Egg yolk and albumen percentages were similar among treatments. However, eggshell percentage increased (P < 0.05) with increasing level of dietary EF1. Layers fed EF1 deposited more (P < 0.05) total n-3 poly-unsaturated fatty acids than layers fed the control diet. For example, linolenic acid (LNA) increased (P < 0.05) by 610% in layers fed 22.5% EF1 compared with those fed the control diet during week 2. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were also increased (P < 0.05) as a result of EF1 supplementation. However, dietary EF1 had no effect on egg cholesterol, but significantly reduced (P < 0.05) AMEn and apparent total tract digestibility of dry matter, organic matter, crude protein and gross energy.In Experiment 2, incorporating EF2 up to 9% of the diet had no effect on feed intake, egg production, feed conversion ratio, and egg components. However, dietary EF2 significantly increased (P < 0.05) total n-3 poly-unsaturated fatty acids in egg yolk, plasma and liver tissues. For example, when compared to the control diet, hens fed 9% EF2 had higher LNA (551%, 558% and 363%, respectively) and DHA (60%, 46% and 66%, respectively) in yolk, plasma and liver at week 8. Egg cholesterol was not affected by dietary EF2. Similarly, AMEn and apparent total tract nutrient digestibility of dry matter, organic matter, and gross energy were significantly reduced (P < 0.05) among birds fed 9% EF2.In conclusion, moderate levels of EF1 (i.e. 7.5%) and EF2 (i.e. 6%) are effective dietary strategies for the production of omega-3 enriched eggs (n-3 fatty acids ≥ 300 mg per egg according to regulations of the Canadian Food Inspection Agency), without compromising egg production and nutrient digestibility. Deux études ont été effectués pour évaluer l'effet de deux types de moulées à base des graines de lin extrudées (EF1 et EF2; lin:luzerne 4:1) sur le dépôt des acides gras oméga-3 et du cholestérol dans l'oeuf, les paramètres de production, les composants de l'œuf (les pourcentages du jaune, l'albumine et de coquille), et la digestibilité totale apparente des nutriments chez des poules pondeuses. En outre, dans l'étude 2,… Advisors/Committee Members: Arif Mustafa (Internal/Supervisor), Bushansingh Baurhoo (Internal/Cosupervisor2).