Effects of Ambient Temperature and Dietary Vitamin E or Ascorbic Acid Supplementation on the Lipid Metabolism of Taiwan Country Chickens

壹、中文摘要 以二個試驗探討不同環境溫度及飼糧中添加維生素E或抗壞血酸對台灣土雞生長性能、血液成分性狀、肝臟中脂質蓄積、肝臟脂質合成相關酵素活性及肌肉脂肪酸組成之影響。 試驗雞隻採用國立中興大學畜產系育成體重相近之B×L2品系台灣公土雞，雞隻採籠飼飼養於環境溫度控制室中，試驗區分為二個環境溫度處理組，分別為(1)持續高溫組(34±1℃)(2)持續適溫組(24±1℃)。試驗一兩個溫度處理組再區分為三個處理組，分別為基礎飼糧處理組、基礎飼糧添加10 ppm維生素E處理組及基礎飼糧添加100 ppm維生素E處理組。試驗二兩個溫度處理組再區分為三個處理組，分別為基礎飼糧處理組、基礎飼糧添加150 ppm維生素E處理組及基礎飼糧添加500 ppm抗壞血酸處理組。兩個試驗皆使用15~35日齡之雞隻進行研究，每處理組5隻、三重複，飼料及飲水採任食。試驗期均為三週，試驗之雞隻共使用180隻。 試驗一結果顯示，於生長性狀方面，持續高溫處理組與適溫組比較，雞隻之隻日增重、隻日飼料採食量顯著(P0.05)，但持續高溫處理組有較低之趨勢；持續高溫處理顯著(P0.05)。飼糧中添加維生素E對生長性狀無顯著之改善效果；於持續高溫下，隨著飼糧中維生素E添加量之增加，呈直線顯著(P<0.05)提高相對肝臟重量，並有降低相對腹脂重量之趨勢(P=0.051)；另方面，隨著飼糧中維生素E添加量之增加，有提高血漿中甲狀腺素濃度之趨勢(P=0.052)及顯著(P<0.05)降低肝臟中總膽固醇與提高三酸甘油酯含量及提高總脂質含量之趨勢(P=0.052)，並提高ATP-CCE(P<0.05)與NADP-MDH之活性(P<0.05)，降低腿肉中飽和脂肪酸含量(P<0.05)，提高腿肉中多不飽和脂肪酸含量(P<0.05)及不飽和度(P<0.05)。 試驗二結果顯示，環境溫度對雞隻各種性狀之影響與試驗一相類似；而添加150 ppm維生素E之影響趨勢亦與試驗一相類似，但較不明顯；飼糧中添加500 ppm抗壞血酸對雞隻生長性狀無顯著之改善效果，對脂質代謝方面，除顯著(P0.05)。Summary Two trails were carried out to study the effect of ambient temperature and dietary vitamin E (α-tocopherol,coated;VE) or ascorbic acid (L-ascorbic acid,coated;AA) supplementation on growth performance, blood parameters, lipid contents in the liver, hepatic lipogenic-related enzymes activities and muscle fatty acid compositions. Male Taiwan country chickens line B×L2 bred by Dept. of Animal Husbandry, National Chung-Hsing University, were used. Chickens were housed in wire cages in environmental chamber. The trail were divided into two ambient temperature treatments which were (1) constant high temperature (34±1℃) and (2) constant moderate temperature (24±1℃). In trail 1, each temperature treatment was redivided into three treatments which were basal diet treatment, basal diet supplemented with 10 ppm VE and basal diet supplemented with 100 ppm VE. In trail 2, each temperature treatment was redivided into three treatments which were basal diet treatment, basal diet supplemented with 150 ppm VE and basal diet supplemented with 500 ppm AA. Male chickens at 15~35 days old were used in two trails and each treatment was 3 replicates with 5 birds. Feed and water were supplied ad libitum. Experimental period was 3 weeks and a total of 180 male chickens were used. The results of trail 1 indicated that the growth performance of birds raised under constant high temperature were significantly decreased (P0.05) but it tended to be lower under constant high temperature. The concentration of total lipid and total cholesterol in the plasma and the content of triglyceride in the liver were significantly decreased (P<0.05) and significantly increased (P<0.05) the total cholesterol content in the liver under constant high temperature. The NADP-MDH activity was significantly decreased (P<0.05) and the ATP-CCE and FAS activities were tended to decrease under constant high temperature, however, G6PDH activity had no significantly different between two temperature treatments. Birds raised under constant high temperature significantly decreased (P<0.05) the unsaturated fatty acid / saturated fatty acids ratios of thigh meat. Addition of vitamin E to the basal diet had no significantly effect on the growth performance of Taiwan country chickens. The relative liver weight tended to increase (P<0.05) and the abdominal fat weight tended to decrease (P=0.051) as dietary vitamin E supplementation increased. In the other hand, the thyroxine level in the plasma tended to increase (P=0.052), and the triglycerid and the total cholesterol content were significantly increased (P<0.05) in the liver when birds raised under high temperature. Compared with birds raised under comfortable temperature (24℃), birds raised under high temperature had higher (P