【作者】 李慧；

【导师】 邹晓庭；

【作者基本信息】 浙江大学 ， 动物营养与饲料科学， 2010， 硕士

【摘要】 本课题以罗曼蛋鸡为实验对象,研究日粮添加γ-氨基丁酸(GABA)对其夏季高温期产蛋性能和抗热应激性能的影响,并从血清生化指标、抗氧化、免疫及内分泌的角度探讨GABA的抗热应激机理。试验选用480只320日龄罗曼蛋鸡,随机分为5组,每组3个重复,每重复32只,分别饲喂添加0(对照组)、25、50、75、100 mg/kg GABA的试验日粮,试验期60d。饲养试验进行至第20,40,60天,每组随机取18枚(每重复6枚),留作分析蛋品质。试验结束后从每个重复选择3只蛋鸡,每组9只,进食24小时后空腹称个体重,翅静脉采血,制备血清,然后屠宰取样。结果表明：(1)生产性能：GABA对蛋鸡产蛋性能有提高作用,其中以50 mg/kg组效果最为显著,产蛋率提高3.20%(P<0.05),平均蛋重提高3.51%(P<0.05),料蛋比降低4.78%(P<0.05);25,75,100 mg/kg组产蛋率分别提高2.59%(P<0.05),1.14%(P<0.05),1.35%(P<0.05),平均蛋重分别提高2.09%(P<0.05),1.74%(P<0.05),1.51%(P>0.05)：50,75 mg/kg组日均采食量分别比对照组提高2.59%,1.46%(P>0.05), 100mg/kg组采食量降低1.84%(P>0.05),25 mg/kg组采食量与对照组无明显差异。(2)蛋品质及鸡蛋营养成分：50 mg/kg GABA组改善蛋品质效果最好,与对照组相比,蛋壳强度提高14.59%(P<0.05),蛋白高度增加5.37%(P>0.05),哈氏单位提高4.55%(P>O.05)；其他试验组蛋品质也有提高的趋势,差异均不显著。各试验组蛋黄胆固醇含量分别降低5.93%(P>0.05),9.20%(P>O.05),7.65%(P>0.05),7.24%(P>0.05)；各组间的鸡蛋中水分含量,蛋黄、蛋清相对比重及蛋黄含脂率等指标差异均不显著。各试验组鸡蛋蛋清及蛋黄氨基酸总量均高于对照组,其中50 mg/kg GABA组蛋清中氨基酸总量提高2.49%(P>0.05),蛋黄中氨基酸总量提高2.57%(P>0.05)。4个试验组蛋清中谷氨酸含量分别比对照组高3.12%(P>0.05),5.48%(P>0.05),4.18%(P>0.05),3.19%(P>0.05)；蛋黄中谷氨酸含量分别提高3.73%(P>0.05),5.72%(P>0.05),4.48%(P>O.05),4.23%(P>0.05)。4个试验组蛋清中酪氨酸含量分别比对照组高1.98%(P>0.05),5.25%(P>0.05),4.92%(P>0.05),3.28%(P>0.05)；蛋黄中酪氨酸含量分别提高3.48%(P>0.05),5.22%(P>0.05),4.35%(P>0.05),3.48%(P>0.05)。(3)血清生化指标：与对照组相比,各试验组血清钙水平分别升高3.42%(P＜0.05),12.84％(P＞0.05),10.78％(P>0.05),0.51％(P＞0.05);血清磷水平分别提高22.03%(P<0.05),26.27%(P<0.05),25.00%(P<0.05),10.59(P>0.05)；血糖水平分别升高16.52%(P>0.05),30.70%(P<0.05),13.51%(P>0.05),5.96%(P>0.05)；血清尿素氮水平分别降低7.69%(P>0.05),13.00%(P>0.05),4.77%(P>0.05),4.77%(P>0.05)；血清胆固醇水平分别降低18.41％(P<0.05),20.21％(P<0.05),19.49％(P<0.05),9.75％(P＞0.05);总蛋白分别提高9.63%(P>0.05),11.43%(P<0.05),1.98%(P>0.05),4.32%(P>0.05)；白蛋白分别提高4.67%(P>0.05),13.59%(P>0.05),0.63%(P>0.05),0.86(P>0.05)。50 mg／kg组谷草转氨酶及谷丙转氨酶活性分别降低6.81%(P>0.05),7.24%(P>0.05)；乳酸脱氢酶活性降低8.42%(P>0.05),其余试验组的血清酶活性与试验组相比差异不明显。(4)抗氧化性能：与对照组相比,各试验组血清GSH-Px活性分别提高8.1%(P<0.05),10.71％(P<0.05),1.17％(P＞0.05),0.50％(P>0.05);血清SOD活性分别提高3.14%(P>0.05),5.94%(P<0.05),4.45%(P>0.05),2.39%(P>0.05);血清MDA水平分别降低31.05%(P<0.05),44.55%(P<0.05),40.59%(P<0.05),35.91%(P<0.05)。肝脏中抗氧化酶活性均得到提高,其中,50 mg／kg组肝脏中GSH-Px、SOD活性分别提高9.45%(P<0.05),4.09%(P<0.05);MDA含量降低11.14%(P>0.05)。(5)免疫性能：与对照组相比,50 mg／kg组IgG,IgA及补体C3水平分别提高22.88%(P<0.05),21.99%(P<0.05),26.31%(P<0.05)；其他组与对照组相比无显著性差异。免疫器官指数,IgM及补体C4水平在各组间无显著差异。(6)内分泌激素：与对照组相比,50 mg／kg GABA组血清促卵泡激素(FSH)及雌二醇(E2)水平分别提高18.67%(P<0.05)和13.03%(P<0.05),催乳素水平降低11.56%(P>0.05),血清胰岛素水平升高69.67%(P<0.05)。血清三碘甲腺原氨酸(T3)及游离三碘甲腺原氨酸(FT3)水平分别升高23.78%(P<0.05),19.01%(P<0.05)。(7)十二指肠内容物消化酶：与对照组相比,各试验组淀粉酶活性分别提高2.84%(P>0.05),9.78%(P>0.05),4.10%(P>0.05),2.84%(P>0.05);脂肪酶活性分别提高1.28%(P>0.05),9.08%(P>0.05),9.22%(P>0.05),3.43%(P>0.05);50,75,100mg/kg组胰蛋白酶活性分别提高7.87%(P>0.05),4.28%(P>0.05),3.40%(P>0.05),25 mg/kg组胰蛋白酶活性与对照组相比无明显差异。本研究结果提示：①日粮添加GABA提高了夏季高温条件下蛋鸡产蛋率和平均蛋重,降低了料蛋比；50 mg/kg处理效果最佳；②GABA促进了高温条件下FSH、E2等生殖激素及甲状腺激素的分泌,维持高温环境下蛋鸡内分泌系统稳定,以提高蛋鸡产蛋率；③GABA提高了血清中总蛋白含量,促进机体合成蛋白；提高了葡萄糖和血清钙磷水平,对于维持机体的电解质平衡有一定作用；④GABA提高了血清及肝脏中抗氧化酶活性,血清免疫球蛋白及补体含量,从而增强蛋鸡的抗氧化性能及免疫性能,减轻热应激的危害。更多还原

【Abstract】 This study was designed to investigate the effects of y-aminobutyric acid (GABA) on laying performance, egg quality and heat stress resistance capability in hens under high temperature in summer. And to apporach the mechanism from serum biochemical indexes, antioxidation, immunity and endocrine.480 Roman laying hens of 320 days of age were randomly divided into five groups with three replicates of 32 layers. One group received the basal diet as a control while the others received diets supplemented with 25,50,75,100 mg/kg GABA as treatment groups. The experiment lasted for 60 days. At 20,40,60 d of the experiment, we collected 18 eggs randomly from each group (6 eggs each repletion) to test the egg quality. At the end of the experiment,45 laying hens were slaughtered, and samples were collected for analysis.The results showed as following:(1) Production performance:production performance of laying hens was improved in all treatments, and 50 mg/kg was the best dosage which significantly increased Laying rate, average egg weight by 3.20%(P<0.05) and 3.51%(P<0.05), decreased feed weight/egg weight by 4.78%(P＜0.05). Laying rate of 25,75,100 mg/kg groups were significantly increased by 2.59%(P＜0.05),1.14%(P<0.05), 1.35%(P＜0.05), respectively. Average egg weight of 25,75,100 mg/kg groups were increased by 2.09%(P＜0.05),1.74%(P<0.05),1.51%(P>0.05) respectively. ADFI of 50,75 mg/kg groups was increased by 2.59%(P>0.05),1.46%(P>0.05), ADFI of 100 mg/kg group was decreased by 1.84%(P>0.05), and 25 mg/kg group had no difference on ADFI compared with control group.(2) Egg quality and nutrient ingredient:compared with control group,50 mg/kg GABA increased the eggshell strength, Egg shell thickness, albumen height and Haugh unit by 14.59%(P＜0.05),5.26%(P>0.05),5.37%(P>0.05),4.55% (P>0.05), respectively. The other treatment groups also improved shell thickness, yolk color and Haugh unit (P>0.05). Cholesterin of egg yolk in all the treatment groups were decreased by 5.93%(P>0.05),9.20%(P>0.05),7.65%(P>0.05), 7.24%(P>0.05), respectively. There were no significant differences on water percentage, yolk weight proportion, albumen weight proportion and yolk fat percentage between all the groups. Amino acid of egg:the total amino acid of albumen or yolk in all treatment groups were increased (P>0.05), and 50mg/kg GABA increased the total amino acid of albumen and yolk by 2.49%(P>0.05), 2.57%(P>0.05), respectively. Glutamic acid of egg albumen was increased by 3.12%(P>0.05),5.48%(P>0.05),4.18%(P>0.05),3.19%(P>0.05), respectively in treatment groups. Glutamic acid of egg yolk was increased by 3.73%(P>0.05), 5.72%(P>0.05),4.48%(P>0.05),4.23%(P>0.05), respectively in treatment groups. Tyrosine acid in egg albumen was increased by 1.98%(P>0.05),5.25% (P>0.05),4.92%(P>0.05),3.28%(P>0.05), respectively in treatment groups. Tyrosine acid in egg yolk was increased by 3.48%(P>0.05),5.22%(P>0.05), 4.35%(P>0.05),3.48%(P>0.05), respectively in treatment groups.(3) Serum biochemical indexes:compared with control group,4 treatment groups increased content of Ca by 3.42%(P>0.05),12.84%(P>0.05),10.78%(P>0.05), 0.51%(P>0.05), respectively. Increased the serum P by 22.03%(P<0.05),26.27% (P<0.05),25.00%(P<0.05),10.59%(P>0.05), respectively. Increased the serum GLU by 16.52%(P>0.05),30.70%(P<0.05),13.51%(P>0.05),5.96%(P>0.05), respectively. And decreased BUN by 7.69%(P>0.05),13.00%(P>0.05),4.77% (P>0.05),4.77%(P>0.05), respectively. Decreased CHO by 8.41%(P＜0.05), 20.21%(P＜0.05),19.49%(P＜0.05),9.75%(P>0.05), respectively. Increased the total protein by 9.63%(P>0.05),11.43%(P＜0.05),1.98%(P>0.05),4.32% (P>0.05), respectively. And increased the serum albumen by 4.67%(P>0.05), 13.59%(P>0.05),0.63%(P>0.05),0.86%(P>0.05), respectively.50 mg/kg GABA decreased the GOT and GPT levels by 6.81%(P＜0.05),7.24%(P>0.05), respectively, decreased LDH (lactate dehydrogenase) by 8.42%(P>0.05). And the serum enzyme activity had no obvious difference between the others treatment groups.(4) Antioxidation parameters:compared with control group,4 treatment groups increased the serum GSH-Px activity by 8.1%(P<0.05),10.71%(P＜0.05),1.17% (P>0.05),0.50%(P>0.05), respectively. The serum SOD activity were increased by 3.14% (P>0.05),5.94% (P＜0.05),4.45%(P>0.05),2.39% (P>0.05), respectively. The serum MDA content were significantly decreased by 31.05% (P＜0.05),44.55%(P＜0.05),40.59%(P＜0.05),35.91%(P<0.05), respectively. The enzymes activity of liver was also increased.50 mg/kg GABA increased the GSH-Px and SOD activity in liver by 9.45(P＜0.05),4.09%(P＜0.05), respectively, and decreased the content of MDA in liver by 11.14%(P>0.05).(5) Immune parameters:compared with control group,50 mg/kg GABA increased the levels of IgG, IgA, complement 3 by 22.88%(P＜0.05),21.99%(P＜0.05),26.31% (P＜0.05), respectively. The other treatment groups had no significant effect on levels of IgG, IgA, and complement 3. Immune Organ Index, IgM, complemente C4 had no significant difference among all the groups.(6) Endocrine hormones:compared with control group,50 mg/kg GABA significantly increased the concentration of FSH, E2 by 18.67%(P＜0.05),13.03%(P＜0.05) respectively, decreased the concentration of PRL by 11.56%(P>0.05). The level of serum insulin, T3 and FT3 was significantly increased by 69.67%(P＜0.05), 23.78%(P＜0.05),19.01%(P＜0.05), respectively in 50 mg/kg group.(7) Digestive enzymes activity:compared with control group,25,50,75,100 mg/kg GABA increased the amylase activity by 2.84%(P>0.05),9.78%(P>0.05),4.10% (P>0.05),2.84%(P>0.05), respectively. And increased the lipase activity by 1.28%(P>0.05),9.08%(P>0.05),9.22%(P>0.05),3.43%(P>0.05), respectively. 50,75, 100mg/kg GABA increased parenzyme activity by 7.87%(P>0.05),4.28% (P>0.05),3.40%(P>0.05), respectively. And 25 mg/kg GABA had no obvious effect on parenzyme activity.The result indicated that:①supplement with GABA in diet could effectively improve the production performance and egg quality of laying hens during high temperature in summer, and 50mg/kg was the best dosage.②GABA could facilitate the secretion of FSH and E2, and inhibit the secretion of PRL. GABA could enhance the secretion of thyroid gland, maintain the stability of endocrine system and alleviate heat stress, to increase the laying rate.③GABA could increase total protein levels; enhance the capacity of protein synthesis of laying hens. It could increase the level of GLU, serum Ca and P.④GABA could enhance the antioxidant capacity by increasing the activity of antioxidant enzymes in liver and strengthen immune function by increasing the concentration of serum immunoglobulin and complement. So it can alleviate the heat stress.更多还原