Graduate Thesis Or Dissertation
 

Enzyme Supplementation of Layer Hen Diets Containing Whole Flaxseed to Increase n-3 Fatty Acids in Chicken Eggs

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  • Flaxseed is a rich source of alpha-linolenic acid (ALA). Feeding laying hens flax seed can increase n-3 fatty acids content (FA) in eggs, thus increasing human intake of n-3 FA. However, non-starch polysaccharides (NSP), which decreases digestibility of dietary lipids and proteins. Addition of carbohydrase enzymes to flax-based layer diets can alter the anti-nutritive effects of NSP. Three experiments were conducted to investigate the effect of dietary supplementation of flaxseed and carbohydrase enzyme on hen production performance, egg quality, egg and hen liver tissue FA composition, and foregut morphology in layer hens. A total of seventy-two brown layer hens were assigned to one of four dietary treatments: corn-soybean based diet (Control), Control plus 10% flax (Diet 1), Diet 1 +0.05% carbohydrase enzyme (Diet 2), and Diet 1 + 0.1% carbohydrase enzyme (Diet 3). All diets were isocaloric and isonitrogenous. Hens received the dietary treatments for a total of 4 months. Hens fed Diet 1 exhibited a trend for highest egg hen day production among the four dietary treatments (P=0.09). Hen age led to a reduction in egg production in all four dietary treatments during the four month feeding trial (P<0.0001). Both egg weight and yolk weight were significantly higher in hens fed Diet 2 (P=0.008). During the six week storage period, egg weight and yolk weight were significantly higher in hens fed Diet 2 and Diet 3 (P=0.005, P=0.044) as compared to the Control. Hens receiving Diet 3 showed a trend for a high yolk pH (P=0.083), while Diet 3 displayed a significantly higher albumen pH (P<0.0001). Egg fatty acids were influenced by diet composition. Linoleic acid (LA) and arachidonic acid (AA) were highest in Control eggs (P<0.0001). ALA was highest in eggs from hens fed Diet 3 (P=0.009). DHA was significantly increased in eggs from hens fed Diet 1, Diet 2, and Diet 3 (P<0.0001) relative to the Control. Total n-3 FA was highest in hens consuming Diet 3 (P<0.0001) (>1.7 fold-increase compared to Control). Total long chain (>20 carbons) n-3 FA concentrations were highest among eggs from hens fed Diets 1, 2, and 3 (P<.0001). Egg total lipids showed no significant difference among the four dietary treatments. A significant increase in ALA content was observed in the liver of hens fed Diets 1 and 3 (P<.0001) relative to the Control diet. There was a significant increase in LA and AA in liver of hens fed the Control as compared to Diets 1, 2, and 3 (P<0.0001). Furthermore, total n-6 FA were also significantly higher in the Control and Diet 1, while there was a significant increase in total n-3 FA seen in fed receiving Diet 1, 2, and 3. Liver DHA (22:6 n-3) content in hens fed Diets 1, 2, and 3 increased by an average of 2.27% relative to the Control. As for long chain n-3, there was a significant increase in the liver of hens receiving Diets 1, 2, and 3 as compared to the Control. Hen liver total lipids were significantly higher in hens fed Diets 1, 2, and 3 (P=0.0009). There was a significant increase in thiobarbituric acid-reactive substances (TBARS) eggs from in hens fed Diet 3 (P<.0001). In the duodenum, flaxseed and enzyme supplementation led to a significant increase in villi height (P<0.0001). Villi width was also significantly greater in hens fed Diets 1, 2, and 3 (P<0.0001). However, the addition of flaxseed and enzyme led to a trend with Diet 3 having the lowest crypt depth (P= 0.066) in the duodenum. Hens fed Diet 1 and Diet 3 had significantly increased villi height:crypt depth ratio (P<0.0001). In the jejunum, hens fed flaxseed and enzyme supplementation also had significantly increased villi height (P<0.0001). In addition, hens fed Diets 2 and Diet 3 displayed a significant increase in villi width (P<0.0001). Both crypt depth and villi height:crypt depth ratio showed no significant difference among the four dietary treatments. In conclusion, the combination of whole flaxseed plus carbohydrase enzymes leads to degradation of NSP in flaxseed and increases the availability of ALA and other nutrients. Egg and liver from hens fed Diet 2 and 3 experienced over a 50% increase in total n-3 FA. There is evidence that feeding hens an enzyme supplement along with high levels of ALA produces significant changes in gut morphology, increasing jejunum villi surface area. These studies confirm that the use of carbohydrase enzymes can result in degradation of NSP in whole flaxseed and increase availability of ALA and other nutrients to layer hens without hindering production performance.
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