【作者】 黄进；

【导师】 王恬；

【作者基本信息】 南京农业大学 ， 基础兽医学， 2008， 博士

【摘要】 本研究以AA肉鸡为试验对象,在基础日粮中分别添加O%(对照组)、0.5%(SL1)、1.0%(SL2)和2.0%(SL3)四个水平的大豆磷脂和添加2%大豆油(SO)、2%的以25/75(SOL1)和50/50(SOL2)比例混合的大豆磷脂/大豆油混合物饲喂6周。通过饲养试验、屠宰试验,从整体、组织、内分泌及分子水平上研究大豆磷脂对AA肉鸡脂肪代谢及肉品质的影响。探讨大豆磷脂调控脂肪代谢和改善AA肉鸡胴体品质的机理并比较了大豆磷脂替代大豆油对肉仔鸡的作用效果,为大豆磷脂作为营养再分配剂在养鸡业上的应用提供依据。1大豆磷脂对AA肉鸡生产性能、营养物质消化利用率及消化酶活性的影响结果表明:日粮中添加不同水平大豆磷脂的各组中,SL2组具有较好的生长性能。大豆磷脂替代不同比例大豆油的各组中,SOL1、SOL2组的生长性能高于其它各组。SL3组42d时肝脏的相对重量显著高于其它各组(P＜0.05)。19-21d,SL2组和SOL1组干物质、粗蛋白、粗脂肪的消化利用率高于其它各组;39-41d,对照组,SL1组的表观代谢能(AME)显著低于其它各组(P＜0.05);SL3组与对照组相比,粗脂肪的消化率显著提高(P＜0.05),但SO、SOL1、SOL2和SL3之间,粗脂肪的消化率没有显著差异(P＞0.05)。添加磷脂的各组及SO组肉鸡42日龄黏膜麦芽糖酶活性都显著高于对照组(P＜0.05),蔗糖酶、脂肪酶和蛋白酶的活性各组之间没有显著差异(P＞0.05)。结果显示:日粮中添加1%的大豆磷脂或以25/75比例混合的大豆磷脂/大豆油混合物时,AA肉仔鸡可以获得较高的生长性能。说明大豆磷脂对AA肉鸡的生长性能的影响存在剂量效应,日粮中添加一定比例的大豆磷脂或大豆磷脂替代一定比例的大豆油对AA肉鸡的生长性能具有促进作用。2大豆磷脂对AA肉鸡体脂分布及肉品质的影响本试验研究了大豆磷脂对AA肉鸡体脂分布、肉质食用性状、肌肉脂肪酸组成、胆固醇含量及抗氧化性能的影响。结果表明,日粮中添加1%大豆磷脂可以显著提高腿肌脂肪含量(P＜0.05);添加磷脂的各组及大豆油组胸肌48h滴水损失、压力损失和烹饪损失均低于对照组。与对照组相比,日粮中添加1%大豆磷脂具有提高胸肌的红色度的趋势(P=0.072);大豆磷脂具有提高42日龄AA肉鸡肌肉亚油酸(C18:2)、亚麻酸(C18:3)及多聚不饱和脂肪酸总量的作用;各组之间肌肉脂质过氧化产物(MDA)含量及胆固醇含量没有显著差异。不同混合比例的大豆磷脂/大豆油组(SO、SOL1、SOL2、SL3)之间,胸肌和腿肌的食用品质及多不饱和脂肪酸的含量没有显著差异(P＞0.05)。结果提示大豆磷脂具有调控体脂分配,提高鸡肉不饱和脂肪酸含量,改善肉质的作用;大豆磷脂可以完全替代大豆油添加在肉仔鸡的日粮中,而不会对鸡肉品质和脂肪酸组成产生不良影响。3大豆磷脂对AA肉鸡血清脂蛋白含量、脂肪代谢相关激素及抗氧化性能的影响本试验研究了日粮中添加不同水平大豆磷脂和大豆磷脂替代不同比例大豆油对AA肉鸡血清抗氧化性能,血清脂蛋白含量及脂肪代谢相关激素的影响。结果发现,大豆磷脂对肉鸡的血清总胆固醇(TC)和低密度脂蛋白胆固醇(LDL-C)具有降低作用(P＜0.1),高密度脂蛋白胆固醇(HDL-C)的含量有被提高的趋势(P＜0.06)。对照组载脂蛋白A(apoA)含量显著高于SL2组(P＜0.05)。各组之间脂蛋白B(apoB)含量差异不显著(P＞0.05)。与对照组相比,SL3组有较高的胰岛素水平(INS)(P＜0.05)。各组甲状腺素(T4)、胰高血糖素(Glu)。大豆磷脂具有很好的降低血清MDA含量的作用,并以日粮中添加1%大豆磷脂效果最为显著(P＜0.05),但对血清超氧化物歧化酶(SOD)的活性没有显著影响(P＞0.05)。结果提示:大豆磷脂具有改善血清中脂蛋白组成和抑制血清脂质氧化的作用。大豆磷脂抗氧化性能可能来自其良好的乳化作用和对细胞膜组成的改善。4大豆磷脂对AA肉鸡脂肪代谢相关酶活性和基因表达的影响本试验研究了大豆磷脂对肉鸡脂质代谢相关酶活性的影响,并测定了日粮中添加不同水平大豆磷脂(Cont.、SL1、SL2和SL3)和不同混合比例的大豆磷脂/大豆油(SO、SOL1和SOL2)对苹果酸酶(ME),脂肪酸合成酶(FAS),乙酰辅酶A羧化酶(ACC)和3-羟基-3-甲基-戊二酰辅酶A还原酶(HMG-CoAR)基因表达的影响。结果表明:SL2和SL3组血清脂蛋白脂酶(LPL)活性显著高于其它各组(P＜0.05),SL3和SO组肝脏肝脂酶(HL)活性显著高于其它各组(P＜0.05)。血清肝脂酶(HL)和总脂酶(TL)活性各组之间没有显著差异(P＞0.05)。肝脏ME、FAS、ACC和HMG-CoAR mRNA的表达量随着大豆磷脂的添加量提高而升高。结果提示:大豆磷脂可以提高肉仔鸡肝脏脂解酶的活性,从而提高脂蛋白的分解。日粮中添加2%大豆磷脂显著提高脂肪酸合成酶及胆固醇合成酶基因表达的现象可能与机体的补偿性合成有关。大豆磷脂对脂肪代谢的调节可能与机体脂肪的沉积状况及日粮的组成有关,而不是单纯地通过抑制脂肪合成酶基因的表达来实现的。更多还原

【Abstract】 This study was conducted to examine the effects of soy-lecithin on lipid metabolism and meat quality in broiler chickens.420 1-day-old Arbor Acres(AA) chicks were given a corn/soybean meal basal diet supplemented with different levels of soy-lecithin 0.0% (Cont.),0.5%(SL1),1.0%(SL2),2.0%(SL3) or basal diet with 2%soy-oil(SO);soy-oil and soy-lecithin mixture in proportion of 75/25(SOL1),50/50(SOL2) for 6 weeks.The growth performance,meat quality and related enzymes activities and gene expression of key enzymes and related hormones,as well as physiological and biochemical parameters were determined.The object of this study was to approach to the mechanism that soy-lecithin may possibly improve on carcass traits of broilers.1 Effects of soy-lecithin supplementation on growth performance, nutrient digestibility and digestive enzyme activities in broilersThe results showed that the body weight(BW) of broilers in SOL1 group was higher than the other groups in 42d(P＜0.05) and that the BW of broilers in SL2 was close to that in SO group.When calculated on the basis of entire experimental period(1-42d),growth performance of broilers in SL2,SOL1 and SOL2 group increased significantly compared with their control counterparts(P＜0.05).The relative weight of liver was increased by feeding with 2%soy-lecithin.The results of digestibility experiment showed that the utilization of dry matter(DM),crude protein(CP) and ether extract(EE) were improved in SL2 and SOL1 group from 19 to 21d.During 39-41d,apparent metabolizable energy(AME) in the groups supplemented with soy-lecithin and soy-oil was higher than the control group. The utilization of EE in SL3 group was higher than the control group(P＜0.05),but no significant effects were observed in the utilization of EE in SO,SOL1,SOL2 and SL3 group(P＞0.05).The growth performance and utilization of nutrients decreased in SL3 group.The activity of maltase in anterior intestinal in soy-lecithin supplemented groups and 2%soy-oil group was higher than the control group(P＜0.05).It is suggested that lecithin exerted a dose dependent manner on the growth performance of broilers.Basal diets supplemented with 1%soy-lecithin and soy-lecithin/soy-oil in a proportion of 25/75 exerted a positive effect on the growth performance during the overall period and improved nutrients digestibility in broilers.2 Effects of soy-lecithin on the body fat distribution and meat quality in broilersThis study was conducted to examine the effects of soy-lecithin on body fat distribution,meat eating quality,muscle fatty acid composition,cholesterol levels and tissue oxidation stability in broiler chickens.The results showed that the percentage of thigh muscle fat was improved when 1%soy-lecithin was supplented to the diets of broilers (P＜0.05).SL3 group had the lowest abdominal fat pad weight.PH value(24h),drip loss (48h) and cooking loss were lower in the groups supplented with soy-lecithin and soy-oil compared with the control group.An increasing tendency was found in red color of breast muscle in soy-lecithin contained diets(P=0.072 between Cont.and SL2).The content of linoleic acid(C18:2),linolenic acid(C18:3) and polyunsaturated fatty acid(PUFA) were increased in the muscle of broilers fed with soy-lecithin.No statistical differences were observed in tissue MDA and cholesteral levies in different treatment groups(P＞0.05).No significant differences were observed among SO,SOL1,SOL2 and SL3 groups when concerned with the eating quality and PUFA content of breast and thigh muscle(P＞0.05). The results of the present experiment implied that soy-lecithin has body fat redistribution capacity,and it can increase unsaturated fatty acid levels and improve the meat qulity in broiler chickens.Soy-lecithin can replace soy-oil supplemented in the diet of broilers and do no negative effects on the quality and fatty acid profiles of chicken.3 Effects of soy-lecithin on serum lipoprotein profiles,lipid metabolism related hormones and antioxidation capacities in broilerThe purpose of this experiment was to determine the effects of soy-lecithin on the serum antioxidation competence,lipoprotein profile and hormones involving in lipid metabolism of broilers.The results showed that serum concentration of total serum cholesterol(TC) and low-density lipoprotein cholesterol(LDL-C) were reduced by soy-lecithin(P＜0.1),whereas high-density lipoprotein cholesterol(HDL-C) had an improving tendency(P＜0.06).Serum apoA levels in the control group was higher than SL2 group(P＜0.05),but had no significant differce compared with the other groups(P＞0.05). Insulin(INS) were elevated in SL3 group compared with control group(P＜0.05).Serum MDA levels were reduced when 1%soy-lecithin were supplented to the diets of broilers (P＜0.05).No significant difference was observed in the activity of SOD.The results indicate that soy-lecithin has cholesterol lowering capacity and that soy-lecithin can improve serum lipoprotein profiles.The antioxidation capacity of soy-lecithin may be related to its emulsification ability and that it can improve the composition of cell membrane.4 Effects of soy-lecithin on activity of lipid metabolic enzymes and expression of genes in broilerThe purpose of this experiment was to determine the effects of soy-lecithin on the activity of lipid metabolic enzymes and lipogenic genes expression in the liver of broiler chickens.At the end of the experiment,samples of serum and liver tissues were taken for analyses of the activity of lipid metabolic enzymes and the expression of selected genes. The hepatic expression of the genes encoding malic enzyme(ME),fatty acid synthase (FAS),acetyl-CoA carboxylase(ACC) and 3-hydroxy-3-methylylutaryl-Coenzyme A reductase(HMG-CoAR) were determined with reverse transcription-polymerase chain reaction(RT-PCR) using SYBR green as a flourophore monitored in a real time mode.The results showed that the activity of serum lipoprotein lipase(LPL) and hepatic lipase(HL) were improved when soy-lecithin were involved in the diets(P＜0.05),but no significant differenc were observed in the activity of serum HL and total lipase(P＞0.05).The abundance of ME,FAS,ACC and HMG-CoAR mRNA were increased with the increasing level of soy-lecithin.The results indicate that soy-lecithin alters the activity of enzymes and that the regulation of fat metabolism in AA broilers is not simply through suppression of hepatic lipogenic gene expression.更多还原