Effects of Dietary Polyunsaturated Fatty Acids and α- Tocopherol on Lipid Metabolism and Egg Quality of Laying Tsaiya Ducks

• Main Authors: Tian-Fwu Chen, 陳添福
• Other Authors: Jenn-Chung Hsu
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/21733992290376493872

博士 === 國立中興大學 === 畜產學系 === 91 === The objective of this study was conducted to determine the effects of dietary polyunsaturated fatty acids and α-tocopherol supplementation on lipid metabolism and egg quality of laying Tsaiya ducks. We conducted four experiments in the study. The corn-soybean basal diets containing CP 19%, ME 2800 kcal/kg, Ca 3.0% and available phosphorus 0.46% were used in these four experiments. All of the experimental diets were formulated to be both isocaloric and isonitrogenous. In experiment I, two percent of tallow (control) and graded levels of refined cod liver oil (RCLO) (FO) at 2, 3, 4, 5, and 6% were supplemented to the basal diet. In experiment Ⅱ, the treatments were as follows: (1) 4% tallow (4%TO) (control), (2) 2% soybean oil + 2% fish oil (2%SBO+2%FO), (3) 2% sunflower oil + 2% fish oil (2%SFO+2%FO), (4) 2% canola seed oil + 2% fish oil (2%CSO+2%FO), (5) 2% sesame oil + 2%fish oil (2%SSO+2%FO) and (6) 4% fish oil (4%FO). In experiment Ⅲ, there were six treatments as follows: 4% tallow (4%TO) (control), 4% fish oil (4%FO), 4% fish oil supplemented with graded levels of α-tocopherol at 100, 200, 300, and 400 mg/kg. These three experiments had 6 treatments with 3 replicates each. A total of 180 laying Tsaiya ducks were allotted into the three experiments each and fed one of the 6 experimental diets for 6 wks. In experiment Ⅳ, a total of 162 laying Tsaiya ducks were allotted into 3 replicates of 3 treatments and fed one of the three experimental diets containing 4% tallow (4%TO), 4% fish oil (4%FO) and 4% fish oil + 400 mg α- tocopherol/kg (4%FO+T400), respectively. Ducks were fed experiment diets for 5 wks (0-5 wks) and subsequently fed the control diet for another 5 wks (6-10 wks). Feed and water were supplied ad libitum throughout the experimental period in these four experiments. The results indicated that the RCLO supplementation levels and different sources of dietary fat did not affect (P>0.05) egg production, egg mass, feed intake, feed efficiency or body weight change. Egg production was increased linearly (P<0.01) with increased dietaryα- tocopherol supplementation. The activities of lipogenic-related enzymes including fatty acid synthetase (FAS), ATP-citrate cleavage enzyme (CCE), acetyl-CoA carboxylase (ACC), NADP-malate dehydrogenase (NADP-MDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) were linearly (P<0.01) decreased as the RCLO levels increased, and these enzyme activities were significantly (P<0.01) increased with increasedα- tocopherol supplementation. The contents of triglyceride and total lipid in the liver and plasma tended to decrease with the RCLO supplementation increased. However, the nonesterified fatty acid concentration (NEFA) tended to increase as RCLO supplementation increased. The higher the RCLO and α- tocopherol supplementation, the less the n-6 polyunsaturated fatty acids (n-6 PUFAs) content and the greater the n-3 polyunsaturated fatty acids (n-3 PUFAs) and α- tocopherol content in the liver, yolks, salted egg and alkalizedegg. The incoporation of EPA, DHA, total n-3 PUFAs andα- tocopherol into egg yolks reached peak levels at days 8 and kept constant till to weeks 5 in ducks fed diet supplemented with 4% RCLO andα- tocopherol 400 mg/kg. Yolk EPA, DHA, total n-3 PUFAs andα- tocopherol contents were linearly (P<0.01) decreased when ducks fed on 4% RCLO+α- tocopherol 400 mg/kg diets for 5 wks and subsequently fed the control diet for another 5 wks. Regarding the organoleptic evaluation, the appearance, color, texture and acceptability of hard boiled-eggs, salted eggs and alkalizedeggs were not significantly different (P>0.05) in the three experiments. Fishy flavor were much higher when 5% and 6% RCLO were supplemented to the diets. Increasing RCLO supplementation and storage period of fresh eggs, salted eggs and alkalizedeggs resulted in increased TBA value. N-3 PUFAs-enriched diet supplementing with α- tocopherol 400 mg/kg improved stability of lipid peroxidation of fresh eggs, salted eggs and alkalizedeggs during storage period and may decrease liver TBA. The activities of SOD and GSH-Px in the liver and plasma were enhanced by fish oil andα- tocopherol. Diet enriched with n-3 PUFAs and supplemented with α- tocopherol significantly increased the activities of antioxidant enzymes. In conclusion, n-3 PUFAs andα- tocopherol-enriched duck egg can be produced by supplementation with 4% RCLO andα- tocopherol 400 mg/kg to the duck diet.