1. Flaxseed is a rich source of α-linolenic acid (ALA, 18:3 n-3). Feeding flaxseed to hens can increase n-3 fatty acids (FA) in eggs. However, non-starch polysaccharides (NSP) in flaxseed decrease nutrient digestibility and can have a negative impact on egg n-3 FA incorporation. Addition of carbohydrase enzymes to flaxseed-based diets can decrease the anti-nutritive effects of NSP. 2. An experiment was conducted to investigate the effect of enzyme supplementation on FA composition and gastrointestinal morphology in hens fed flaxseed. A total of seventy-two, 51-week old brown layer hens were randomly assigned to one of the four dietary treatments (six replicates with three hens per replicate): corn-soybean based diet containing 0% flax (Control), 10% flax (Flax), Flax+0.05% enzyme (Flax+E1), or Flax+0.1% enzyme (Flax+E2) in a 120-day feeding trial. 3. Egg weight was highest in hens fed Flax+E1 (P < 0.05). Yolk weight was higher in Flax+E1 compared with the control and Flax+E2 and was not different from Flax treatment. ALA and total n-3 FA was highest in eggs from Flax+E2 hens (P < 0.05). Addition of enzyme has no effect of on docosahexaenoic acid (DHA), total long chain (>20-C FA), or n-6:n-3 FA ratio in eggs from hens fed flaxseed-based diets (P > 0.05). Over nine-fold increase in hepatic ALA was observed in the liver of hens fed flaxseed-based diets when compared with the control diet (P < 0.0001). No effect of enzyme supplementation was observed on liver ALA, DHA or long chain n-3 FA (P > 0.05). Enzyme supplementation reduced arachidonic acid, total n-6 and LC n-6 FA in liver tissue from hens fed flaxseed-based diets (P > 0.05). 4. Villi height and width was higher in the duodenum and jejunum of hens fed flax-based diets compared to the control (P < 0.05). Enzyme supplementation led to an increase in villi width in jejunum (P < 0.05) in hens fed Flax+E2 (P < 0.05). No effect of diet was observed in the crypt depth and villi height:crypt depth ratio in the jejunum (P > 0.05). 5. It was concluded that enzyme supplementation enhanced total n-3 FA deposition in eggs and liver and influence gastrointestinal morphology in layer hens fed flaxseed.
Keywords: Enzyme; flax; hens; intestinal morphology; n–3 fatty acids.