日粮粗蛋白质水平对肉鸡内源氨基酸损失量的影响

利用一次注射法测定了日粮粗蛋白质分别为17.0%,18.5%及20.0%时肉鸡内源氨基酸损失量.结果表明,不同蛋白质水平下各种氨基酸内源损失量差异不显著(P＞0.05),但适中的粗蛋白质水平(18.5%)有降低内源氨基酸损失量的趋势.     

日粮粗蛋白质水平对肉鸡内源氨基酸损失量的影响

利用一次注射法测定了日粮粗蛋白质分别为16%、18%及20%时肉鸡内源氨基酸损失量。结果表明,不同蛋白质水平下各种氨基酸内源损失量差异不显著(P>0.05),但适中的粗蛋白质水平(18%)有降低内源氨基酸损失量的趋势。     

肉仔鸡内源氨基酸基础损失量估测研究

本研究旨在对肉仔鸡内源氨基酸基础损失量(BAAL)进行估测。选用28日龄爱拔益加商品代肉仔鸡48只,随机分为8组(公、母各4组),每组6只鸡。收集其自由采食无氮日粮后的回肠食糜,测定35日龄肉仔鸡回肠末端内源氨基酸基础损失量。结果表明:BAAL和内源蛋白质的氨基酸组成在公、母鸡间差异不显著(P>0.05),母鸡BAAL值均高于公鸡(P>0.05)。谷氨酸是回肠末端损失最多的氨基酸,天冬氨酸次之,组氨酸损失最少。内源蛋白质的氨基酸组成中,谷氨酸值最高,天冬氨酸次之,组氨酸值最低。     

无氮日粮和酪蛋白对猪回肠内源氨基酸排出量的影响

采用平均体重为 65± 1.85 kg的瘘管猪 6头，研究酪蛋白日粮和无氮日粮对猪回肠内源氨基酸排出量的影响。试验结果表明，酪蛋白组中，除 Met、 Phe、 Pro外，几乎所有的内源氨基酸排出量均高于无氮日粮组。其中， His、 Ile、 Lys、 Thr、 Val、 Asp、 Glu、 Gly、 Ser差异显著 (P< 0.05)。酪蛋白组的内源氮排出量、内源总必需氨基酸、总非必需氨基酸和总氨基酸的排出量均显著高于无氮日粮组 (P< 0.05)，提高的百分比分别为 94.1％、 73.0％、 76.4％和 74.8％。由本次试验结果可以得出，无氮日粮法低估了猪的回肠内源氨基酸损失，而在无氮日粮中添加肽类物质（本试验中添加量为 5％）对内源氨基酸的排出有刺激作用。     

酪蛋白和无氮日粮对猪回肠内源氨基酸排出量的影响

采用平均体重为65±1.85kg的瘘管猪6头，研究酪蛋白日粮、无氮日粮中添加三氧化二铬(PF-Cr)或酸不溶灰分(PF-AIA)对猪回肠内源氨基酸排出量的影响。结果表明，酪蛋白组中，除Met、Phe、Pro外，几乎所有的内源氨基酸排出量均高于PF组；PF-Cr组和PF-AIA组之间内源氨基酸排出量差异不显著(P>0.05)。结论无氮日粮法低估了回肠内源氨基酸排出量，而日粮中添加肽类物质对内源氨基酸的排出有刺激作用；用酸不溶灰分代替三氧化二铬研究回肠内源氨基酸的排泄基本可行。     

不同淀粉来源对生长猪回肠食糜中微生物氮和氨基酸含量的影响

本试验旨在研究淀粉消化性能的差异对生长猪回肠食糜中微生物氮和氨基酸含量的影响.试验采用4×4拉丁方设计,选择4头回肠末端安装有简单T瘘管的杜×长×大三元杂交公猪进行消化代谢试验.结果显示,淀粉来源不同其回肠末端消化率存在差异,在生长猪的回肠末端抗性淀粉有83.07%被消化;糯米淀粉被100%消化,玉米和糙米淀粉介于二者之同,分别有97.63%和96.41%被消化;回肠食糜中氮的流量以采食抗性淀粉日粮组最高(为每千克干物质采食量7.44 g),而食糜氮中微生物氮所占比例以采食糯米组最高(为72.8%);各组回肠食糜氨基酸流量中微生物氨基酸所占比率变化范围为25.43%(玉米组)～45.09%(抗性淀粉组),其中抗性淀粉组Asp、Glu、Ser和Lys的比率明显高于玉米组(P<0.05),但Tyr却低于玉米组(P<0.05);糙米组Arg显著高于抗性淀粉组,而Ala和Leu却比抗性淀粉组低(P<0.05);糯米组Ala和Leu也明显较抗性淀粉组低.     

无氮日粮法与绝食法测定肉仔鸡内源氨基酸损失量的研究

本试验分别用无氮日粮法和绝食法测定肉仔鸡内源氨基酸损失量,并比较两种方法得到的结果之间的差异.选用49日龄健康的AA肉仔鸡公鸡20只,随机分成2组,每组10只,采用48 h空腹+48 h全收粪法进行试验.结果表明,无氮日粮法和绝食法测定的肉仔鸡内源氨基酸中,精氨酸、苏氨酸、胱氨酸、酪氨酸内源损失量之间无显著性差异(P＞0.05);无氮日粮法测定的其他氨基酸内源损失量极显著(P＜0.01)或显著(P＜0.05)高于绝食法;无氮日粮法测定的总氨基酸内源损失量极显著(P＜0.01)高于绝食法.     

无氮日粮法和酶解酪蛋白超滤法测定肉仔鸡内源氨基酸损失量的比较研究

选用40日龄平均体重(2500±50)g商品代AA肉公鸡120只,随机分为无氮日粮组和酶解酪蛋白组,分别饲喂无氮日粮和含酶解酪蛋白的日粮,36h后取回肠末端食糜,测定回肠末端内源氨基酸流量。结果表明:酶解酪蛋白超滤法测定的17种氨基酸的回肠末端内源流量,都高于无氮日粮法的测值,其中12种氨基酸(除甘氨酸、半胱氨酸、酪氨酸、苯丙氨酸和组氨酸)的差异显著(P<0.05);17种氨基酸总的内源流量,超滤法比无氮日粮法高22.7%(P<0.05)。     

日粮纤维对猪回肠微生物氮及微生物氨基酸流量的影响

采用5×5拉丁方设计,对5头大约克阉公猪(大约30kg)实施回盲肠瓣T型瘘管(PVCT)手术,用2,6 二氨基庚二酸(DAPA)标记法,测定以豆饼为基础的半纯合日粮中添加不同浓度的豌豆皮(4%、8%、12%)和纯稻壳(8%)对猪回肠微生物氮及微生物氨基酸流量的影响。结果表明:猪粪总氮中来源于微生物氮的量为74 53%～90 00%,回肠食糜氮中则为30 94%～50 26%;回肠食糜氨基酸流量中,有19 85%(脯氨酸)～51 42%(精氨酸)是来自微生物氨基酸;而微生物氨基酸在回肠内源性氨基酸流量中所占的比例较大,为30 49%(脯氨酸)～98 50%(亮氨酸)。豌豆皮与纯稻壳对猪回肠微生物的作用效果不尽相同,4%的豌豆皮与8%的纯稻壳的作用效果相似,而8%和12%的豌豆皮对猪回肠微生物的影响要高于8%的纯稻壳。     

乳酸菌菌体及全菌液制剂对雏鸡生长性能和盲肠菌群的影响

为了研究不同制备工艺及活菌数的乳酸菌制剂对雏鸡生长性能和盲肠菌群的影响,将格氏乳杆菌菌体和全菌液分别制成活菌制剂用于动物饲养试验。试验选用1日龄的AA肉仔公鸡360只,随机分成6组,每组5个重复,每个重复12只鸡。Ⅰ组和Ⅱ组分别饲喂基础日粮+0.5%和1%菌体制剂;Ⅲ组和Ⅳ组分别饲喂基础日粮+0.05%和0.1%的全菌液制剂(Ⅰ与Ⅲ、Ⅱ与Ⅳ试验组活菌数基本一致);Ⅴ组抗生素组,饲喂基础日粮+0.01%黄霉素;Ⅵ组为对照组,饲喂基础日粮。试验期28 d。结果表明:与对照组相比,日粮中添加乳酸菌制剂可明显改善生长性能,其中高剂量组显著(P<0.05)提高雏鸡日增重,极显著(P<0.01)降低饲料增重比;与抗生素组比,乳酸菌制剂能提高盲肠中乳酸菌数量,抑制大肠杆菌的繁殖;同一添加水平的乳酸菌菌体制剂与全菌液制剂应用效果无显著差异(P>0.05)。由此可知,雏鸡日粮中添加乳酸菌制剂具有促进雏鸡生长和改善盲肠菌群的作用。     

甜菜碱对热应激肉鸡生长性能、十二指肠消化酶活性及盲肠微生物区系的影响

本试验通过在饲粮中添加不同剂量的甜菜碱研究其对热应激肉鸡生长性能、十二指肠消化酶活性及盲肠微生物区系的影响。选取270只14日龄爱拔益加(AA)肉鸡随机分成6组:常温组、热应激组,常温+0.1%甜菜碱组、热应激+0.1%甜菜碱组、热应激+0.2%甜菜碱、热应激+0.4%甜菜碱组。热应激肉鸡饲养在(32±1)℃的高温环境中。每组3个重复,每个重复15只。预试期7 d,正试期21 d。结果表明:1)饲粮添加甜菜碱可极显著增加28~42日龄热应激肉鸡的体重(P<0.01),极显著降低22~35日龄肉鸡料重比(P<0.01);2)除添加0.1%和0.2%甜菜碱饲粮对28日龄热应激肉鸡胰蛋白酶活性无显著影响(P>0.05)和添加0.1%甜菜碱对35日龄热应激肉鸡淀粉酶活性无显著影响(P>0.05)外,不同浓度的甜菜碱均能显著或极显著增加28、35、42日龄热应激肉鸡十二指肠胰蛋白酶、淀粉酶和胰脂肪酶活性(P<0.05或P<0.01);3)饲粮添加甜菜碱极显著提高了28、35、42日龄热应激肉鸡盲肠内乳酸杆菌的数量(P<0.01),极显著降低了产气荚膜梭菌的数量(P<0.01)。由此可见,热应激状态下,在基础饲粮中添加甜菜碱可改善AA肉鸡生长性能,提高十二指肠消化酶的活性,维持盲肠内微生物区系平衡,从而减轻热应激对肉鸡的危害。     

标准回肠消化率在肉鸡饲料原料氨基酸营养价值评定中的应用

为了获得最佳生产性能,配制满足家禽营养需要的日粮配方和将排泄到环境中的过多养分降到最低,已显得尤为重要。关于蛋白质饲料原料,多通过表观回肠消化率反映其利用率。以表观回肠消化率值为基础配制日粮,低估了饲料原料的氨基酸消化率,导致排泄物中养分含量增加。通过内源氨基酸基础损失校正表观回肠消化率所得的标准回肠消化率,能克服表观回肠消化率的局限性。作者讨论了标准回肠氨基酸消化率和内源氨基酸基础损失的估测方法,并对其在肉鸡饲料原料氨基酸营养价值评定中的应用作一总结。     

罗曼公母鸡内源氨基酸排泄量的比较研究

试验选取28周龄健康的罗曼公母鸡各16只,分别分为2个处理,每处理8个重复,每个重复1只鸡,分别饲喂2种试验日粮,即无氮日粮(NFD)和NFD+5%酪蛋白,比较分析2种方法测得的公母鸡内源氨基酸排泄量(EAAL)的差异。结果表明:采用NFD法和NFD+5%酪蛋白所得的公母鸡内源氨基酸和总蛋白质的排泄量有所不同。酪蛋白组能够增加内源氮和内源氨基酸的排泄量,NFD+5%酪蛋白法所测得的内源氮和内源氨基酸排泄量更接近试鸡的真实情况。2种测定方法公鸡内源氮和内源氨基酸的排泄量均高于母鸡的结果。     

免疫应激对肉仔鸡回肠末端内源氨基酸损失的影响

本文旨在研究免疫应激对肉仔鸡内源氨基酸损失的影响。选取体重(390±20)g的16日龄AA肉公雏150只,随机分为3组,每组5个重复。免疫应激组分别于16、18和20日龄按500μg/kg BW向腹腔注射细菌脂多糖,对照组和采食量配对组注射等量生理盐水。21日龄屠宰,取日粮和食糜测定氨基酸和Cr2O3含量,计算回肠末端内源氨基酸流量。结果显示,与配对组相比,免疫应激增加了肉仔鸡除甘氨酸外其余16种氨基酸的回肠末端内源流量(mg/24 h),其中6种氨基酸增幅显著(P<0.05);但与对照组相比,免疫应激减少除半胱氨酸和组氨酸外的其余氨基酸的内源流量,其中8种氨基酸差异显著(P<0.05)。试验结果表明,采食量是影响肉仔鸡内源氨基酸损失的主要因素,谷氨酸是回肠末端内源损失(mg/kg DMI)最大的氨基酸,其次是天冬氨酸、苏氨酸、脯氨酸和丝氨酸,含硫氨基酸内源损失最小。     

A Comparative Study of the Difference Method and the Enzyme-Hydrolyzed Casein Method for Determining True Amino Acid Digestibilities and Endogenous Amino Acid Losses in Duck Feed

In this study,we examined the variations between the difference method and the enzyme-hydrolyzed casein method for determining endogenous amino acid loss and the true amino acid digestibility in ducks fed normal protein-containing diets.These methods were compared to the nitrogen-free(N-free)diet method.The difference method was based on soybean meal as the only protein source,with the experimental diets containing crude protein levels at 15% and 20%.The enzyme-hydrolyzed casein method was based on enzyme-hydrolyzed casein meal as the protein source,with the experimental diet containing a crude protein level of 17.5%.The N-free diet was prepared with starches and paper fibers.In each method,64 Tianfu meat drakes(7-weeks-old)with an average body weight of 2.77±0.16 kg were used and divided into four groups,and fed four different diets.Each group contained four replicates of four drakes and they were force fed trial diets according to the Sirbald method for detecting their apparent amino acid digestibility,endogenous amino acid loss and true amino acid digestibility.The results demonstrated that using the difference,enzyme-hydrolyzed casein and N-free diet methods,endogenous amino acid losses were 0.9946,1.2243 and 0.9297 mg/g dry matter intake(DMI),respectively.The true amino acid digestibility measured by the difference method was 88.93%±4.43%.Using the enzyme-hydrolyzed casein method with two dietary crude protein levels of 15% and 20%,the digestibility was 91.15%±4.33% and 91.97%±4.16%,respectively,and by the N-free diet methods with two dietary crude protein levels of 15% and 20%,it was 88.55%±4.29% and 88.82%±4.61%,respectively.The results suggested that when the dietary protein level was 15% to 20 %,the true amino acid digestibility and endogenous amino acid loss as determined by the difference method was more accurate than the values determined by the enzyme-hydrolyzed casein method.     

A Comparative Study of the Difference Method and the Enzyme-Hydrolyzed Casein Method for Determining True Amino Acid Digestibilities and Endogenous Amino Acid Losses in Duck Feed

In this study, we examined the variations between the difference method and the enzyme-hydrolyzed casein method for determining endogenous amino acid loss and the true amino acid digestibility in ducks fed normal protein-containing diets. These methods were compared to the nitrogen-free (N-free) diet method. The difference method was based on soybean meal as the only protein source, with the experimental diets containing crude protein levels at 15% and 20%. The enzyme-hydrolyzed casein method was based on enzyme-hydrolyzed casein meal as the protein source, with the experimental diet containing a crude protein level of 17.5%. The N-free diet was prepared with starches and paper fibers. In each method, 64 Tianfu meat drakes (7-weeks-old) with an average body weight of 2.77 ± 0.16 kg were used and divided into four groups, and fed four different diets. Each group contained four replicates of four drakes and they were force fed trial diets according to the Sirbald method for detecting their apparent amino acid digestibility, endogenous amino acid loss and true amino acid digestibility. The results demonstrated that using the difference, enzyme-hydrolyzed casein and N-free diet methods, endogenous amino acid losses were 0.9946, 1.2243 and 0.9297 mg/g dry matter intake (DMI), respectively. The true amino acid digestibility measured by the difference method was 88.93% ± 4.43%. Using the enzyme-hydrolyzed casein method with two dietary crude protein levels of 15% and 20%, the digestibility was 91.15% ± 4.33% and 91.97% ± 4.16%, respectively, and by the N-free diet methods with two dietary crude protein levels of 15% and 20%, it was 88.55% ± 4.29% and 88.82% ± 4.61%, respectively. The results suggested that when the dietary protein level was 15% to 20 %, the true amino acid digestibility and endogenous amino acid loss as determined by the difference method was more accurate than the values determined by the enzyme-hydrolyzed casein method.     

理想氨基酸水平对肉鸡生长发育调控技术的研究进展

营养状况可显著影响肌肉的生长,不同的营养因素对肉鸡肌肉生长产生的影响不同。日粮氨基酸是影响肉鸡肌肉最主要的营养成分,适当提高日粮氨基酸水平可降低肉鸡脂肪的沉积,提高胸肉产量,显著改善肉鸡的增重和饲料转化效率。作者主要就日粮理想氨基酸水平对肉鸡生长发育调控技术研究进展进行了综述。