日粮钴铜比例对肉用绵羊维生素B12营养状况及养分代谢的影响

 【目的】研究不同比例的日粮钴铜对肉用绵羊维生素B12营养状况及营养物质消化代谢的影响。【方法】选取20只健康、体重相近（22.9±0.8）kg的小尾寒羊×无角陶赛特杂交一代羯羊,随机分为5组,定量饲喂5种不同日粮,即对照组日粮、4种不同比例的钴铜（0.3﹕10、0.3﹕20、0.6﹕10和0.6﹕20）日粮,试验期8周,试验中期进行消化代谢试验,同时每两周采血样,用电化学发光法、气相色谱法及荧光偏振免疫法测定血浆维生素B12及叶酸含量、甲基丙二酸和同型半胱胺含量。【结果】肉羊日粮添加不同比例的钴铜,血液维生素B12的含量随饲喂时间的延长而增加,6周后趋于稳定。钴水平较高的后两组显著高于其它3组（P＜0.01）,血液维生素B12含量主要取决于钴的摄入量,钴和铜无协同效应。血浆甲基丙二酸和血糖含量随日粮钴铜比例增加而呈下降和上升趋势,同型半胱胺水平无变化,叶酸含量在0.6﹕20 mg?kg-1钴铜添加组显著升高（P＜0.05）。钴和铜的添加比例对DM、OM、CP、NFE表观消化率及氮代谢无影响（P＞0.05）,而配比为0.3﹕20时显著促进脂肪和纤维的消化（P＜0.01）。【结论】肉羊日粮中钴和铜的添加比例对维生素B12营养状况无影响,但适宜配比有利于营养物质的消化代谢。     

铜源和铜水平对岢岚绒山羊生长发育和产绒性能的影响

为研究不同铜源和不同剂量铜对绒山羊生长发育、绒产量和绒品质的影响,选用体重相近的岢岚绒山羊6月龄青年母羊40只,随机分为5组,分别饲喂添加铜水平为0 mg.kg-1(对照组)、25 mg.kg-1和100 mg.kg-1DM硫酸铜2、5 mg.kg-1和100 mg.kg-1DM蛋氨酸铜的日粮,进行为期70 d的试验,其中预试期10 d。结果表明:日粮添加铜显著提高了岢岚绒山羊青年母羊的体重(P0.05),但其绒自然长度和绒细度不受铜添加水平的影响(P0.05)。添加25 mg.kg-1DM硫酸铜或蛋氨酸铜组显著提高了周岁母羊产绒量和绒的伸直长度。因此,在绒山羊青年母羊的日粮中,硫酸铜或蛋氨酸铜添加量以25 mg.kg-1DM为宜。     

日粮铜钼水平对辽宁绒山羊营养物质消化代谢的影响

试验研究日粮铜(Cu)钼(Mo)添加水平对辽宁绒山羊营养物质消化代谢的影响.选用18月龄体重相近、安装永久性瘤胃瘘管的辽宁绒山羊羯羊12只,采用完全随机分组试验设计,分为4组,每组3只.试验分为Mo0期和Mo5期:Mo0期日粮为基础日粮中不加Mo,Mo5期日粮在基础日粮上加Mo(DM)5 mg/kg;每期设4个Cu水平,在基础日粮中添加的Cu(DM)分别为0、19、28和38 mg/kg.结果表明:1)日粮中添加Cu显著提高了辽宁绒山羊的干物质消化率、ADF和NDF的表观消化率,显著降低了干物质采食量和Cu的表观消化率(P<0.05).2)日粮中添加Mo能显著提高ADF、NDF及Cu的表观消化率,但显著降低了氮的表观消化率(P<0.05).3)Cu与Mo互作对干物质消化率、ADF和NDF的表观消化率影响差异显著(P<0.05).在辽宁绒山羊绒毛快速生长期,日粮中添加Mo(DM)5 mg/kg,Cu(DM)19 mg/kg营养物质消化效果最佳.     

硒源和硒水平对种公羊血清和精清抗氧化能力的影响

为研究硒源和硒水平对血清和精清抗氧化酶活性的影响,选择年龄、体重相近、健康的黎城大青羊成年种公羊42只,随机分为7组。分别喂以基础日粮、基础日粮+0.5、1.0、2.0mg·kg-1 DM的酵母硒;基础日粮+0.5、1.0、2.0mg·kg-1 DM的亚硒酸钠,饲喂期60d,试验第60d采集血液和精液样品,测定其抗氧化能力。结果显示,日粮添加硒极显著提高种公羊血清GPxs活性、血清和精清T-AOC含量,显著提高血清、精清SOD和精清GPxs活性;极显著降低血清、显著降低精清中OH-的含量,改善机体的抗氧化能力。硒水平与血清和精清中GPxs、SOD活性、T-AOC和OH-的含量有剂量——效应关系。与1.0mg·kg-1组和0.5mg·kg-1组相比,2.0mg·kg-1组血清、精清中OH-的含量升高,血清GPxs活性下降,精清SOD活性和T-AOC含量下降;日粮硒浓度相同时,其血清GPxs活性高于精清4~10倍,而精清SOD活性高于血清约20倍。成年种公羊日粮中硒的适宜添加量为0.5~1.0mg·kg-1酵母硒或0.5mg·kg-1亚硒酸钠。血清和精清中抗氧化系统存在差异。     

无机铜添加对体外瘤胃微生物发酵的影响

铜是瘤胃微生物活动不可缺少的元素,为研究日粮添加无机铜对瘤胃微生物发酵的影响,本试验用人工瘤胃模拟装置发酵72h研究添加不同水平铜(0、6、12、18、24和30mg/kg干物质(DM))对体外瘤胃微生物发酵挥发性脂肪酸(VFA)产生量、瘤胃液氨浓度和微生物氮产量的影响.结果表明,添加铜可使发酵液不同时间点氨浓度和总氨产量、有机物发酵率显著提高(p<0.05),而对发酵罐中总微生物氮产量没有影响(p>0.05);与不添加的对照组相比添加铜可使发酵液的总VFA、乙酸、丙酸、丁酸浓度明显增加(p<0.05),但乙酸、丙酸、丁酸摩尔比例没有差异(p>0.05).添加铜明显促进瘤胃有机物的发酵,增加瘤胃VFA产生量.     

硒和脂肪酸对绵羊血浆和红细胞膜脂肪酸组成及抗氧化影响

【目的】研究日粮中不同硒（Se）水平和不同来源多不饱和脂肪酸（PUFA）对绵羊血浆和红细胞膜脂肪酸组成及抗氧化的影响。【方法】选用3月龄三元杂交肉用羯羊（无角陶赛特×小尾寒羊×夏洛莱,平均体重为26.3±1.2 kg）32只作为试验羊,采用2×2因子（两个Se水平和两个PUFA来源）设计,随机分为4组,分别饲喂基础日粮＋5%亚麻油（LO）、LO＋2 mg•kg-1硒（LOSe）、基础日粮＋5％葵花油（SO）和SO＋2 mg•kg-1硒（SOSe）。硒以亚硒酸钠的形式添加。试验结束后颈静脉采血,分离血浆及红细胞膜,测定脂肪酸组成及抗氧化特征。【结果】日粮加硒提高了绵羊血浆和红细胞膜的抗氧化能力、血浆trans-11-C18:1浓度和红细胞膜trans-10,cis-12-C18:2浓度,增加了饲喂葵花油日粮绵羊血浆中C20:4n-6和红细胞膜中C20:5n-3浓度,对饲喂亚麻油日粮绵羊无影响;饲喂亚麻油日粮绵羊比饲喂葵花油日粮绵羊血浆和红细胞膜中PUFA更易发生脂质过氧化反应。【结论】绵羊饲喂富含PUFA日粮,同时添加硒可提高血浆和红细胞膜的抗氧化能力,促进PUFA的沉积;添加硒更有利于饲喂葵花油日粮绵羊血浆和红细胞膜中的PUFA沉积。     

日粮添加维生素E对免疫抑制产蛋鸡经济性状下降的调控效应

 【目的】研究在基础日粮中添加维生素E对环磷酰胺诱导产蛋鸡免疫抑制的调控效应。【方法】将270 只健康尼克褐产蛋鸡随机等分为5组,每组3个重复,每个重复18只。Ⅰ、Ⅱ组饲喂基础日粮（维生素E含量44.59 mg•kg-1）,Ⅲ、Ⅳ、Ⅴ组在基础日粮中分别添加50、100和200 mg•kg-1维生素E。试验第5、6、7天,对Ⅱ—Ⅴ组产蛋鸡注射80 mg•kg-1 BW环磷酰胺建立免疫抑制模型,第Ⅰ组注射等量生理盐水。【结果】日粮中添加VE能显著提高免疫抑制产蛋鸡的产蛋性能和饲料转化率、养分表观代谢率（P＜0.05）,提高免疫抑制产蛋鸡脾脏和胸腺的相对重量和新城疫（new castle disease,ND）、H5和H9亚型禽流感（avian influenza,AI）抗体滴度及血浆谷胱甘肽过氧化物酶（glutathione peroxidase,GSH-Px）、超氧化物歧化酶（superoxide dismutase,SOD）活性（P＜0.05）,降低丙二醛（malondialdehyde,MDA）的含量（P＜0.05）;提高免疫抑制产蛋鸡血浆的PGE2、IL-1、IL-6和TNF-α含量（P＜0.05）。【结论】环磷酰胺诱导产蛋鸡所产生的免疫抑制可显著降低其生产性能、养分利用率、抗体水平、抗氧化功能及PGE2和炎性细胞因子含量;日粮中添加维生素E对免疫抑制蛋鸡具有明显的调控效应,且添加水平为50和100 mg•kg-1时效果优于200 mg•kg-1的添加量。     

Dietary copper supplementation modulates performance and lipid metabolism in meat goat kids

Forty-eight male Lezhi black goat kids with similar body weight ((12.09±1.70) kg) and age ((60±5) d) were used to determine the effect of dietary copper (Cu), in the form of reagent grade Cu sulfate (CuSO₄∙5H₂O), on performance, serum lipid profile, and the relative mRNA abundance of genes involved in lipid metabolism.  Goat kids were stratified by body weight and randomly assigned to one of 4 treatment groups.  Each treatment consisted of 12 replicate pens with each pen containing one goat kid.  Treatment groups received the basal diet with no supplemental Cu (control), basal diet plus 10 mg of Cu kg^–1 of dry matter (DM), basal diet plus 20 mg of Cu kg^–1 of DM, or basal diet plus 30 mg of Cu kg^–1 of DM.  Goats were housed individually in pens and fed a high-concentrate pelleted diet for 60 d.  Average daily gain, average daily feed intake and feed:gain of goats were not affected by dietary Cu supplementation (P>0.10).  No differences were detected in serum total cholesterol, triglyceride, and high density lipoprotein cholesterol concentrations of goat kids fed with different Cu concentrations (P>0.05).  However, serum low density lipoprotein cholesterol concentrations decreased linearly (P=0.01) as the concentration of dietary Cu increased.  Intramuscular fat content of longissimus muscle increased (P=0.002) quadratically and liver Cu concentrations increased (P<0.001) linearly as dietary Cu concentration increased.  Compared with the control, dietary supplementation of 20 mg Cu kg^–1 DM decreased the relative mRNA abundance of fatty acid-binding protein 4 (P=0.01) and lipoprotein lipase (P=0.05), and tended to decrease the relative mRNA abundance of carnitine palmitoyltransferase I (P=0.06) in longissimus muscle of goats.  The relative mRNA abundance of peroxisome proliferator-activated receptor alpha (P<0.001), carnitine acetyltransferase (P=0.001), and carnitine palmitoyltransferase I (P=0.001) were also decreased in liver by Cu supplementation.  These results indicate that dietary supplementation of Cu modified lipid metabolism by increasing muscular fat and decreasing serum low density lipoprotein cholesterol, and the modification might be associated with the reduction of relative mRNA abundance of genes for oxidation of long-chain fatty acid in muscle and liver of Lezhi black goat kids.     

不同铜源和水平对肥育绵羊胴体性状、肉品质和脂肪酸组成的影响

为改善和提高绵羊肉的品质,研究不同铜源和水平对肥育绵羊胴体性状、肉品质和脂肪酸组成的影响,本试验选用50只体重相近((23.8±1.6)kg)、3月龄左右的杜泊×蒙古羊杂交一代羯羊,随机分为5组,分别饲喂5种日粮:1)基础日粮(不加铜);2)基础日粮+10 mg/kg(DM)赖氨酸铜;3)基础日粮+20 mg/kg(DM)赖氨酸铜;4)基础日粮+10 mg/kg(DM)碱式氯化铜;5)基础日粮+20 mg/kg(DM)碱式氯化铜.结果表明,日粮中添加铜显著降低了肥育绵羊背膘厚和肾脂率(P<0.01),但对热胴体重、屠宰率和眼肌面积影响差异不显著(P>0.05);日粮中添加铜对肥育绵羊肉品质没有影响(P>0.05),对血浆、肌肉和脂肪组织中脂肪酸组成也无影响(P>0.05).赖氨酸铜和碱式氯化铜2种铜源以及10和20 mg/kg(DM)2种铜水平对肥育绵羊胴体性状、肉品质和脂肪酸组成的影响是相同的,因此,本研究建议绵羊日粮的适宜铜源为碱式氯化铜,适宜铜水平为16.74 mg/kg(DM).     

维生素E和有机微量元素对猪肉质的影响

为了研究添加维生素E和有机微量元素对猪肉质的影响,用170头65 kg左右的PIC杂交商品猪进行为期35 d的饲养试验.为了研究维生素E添加量与有机微量元素对猪肉质的影响,用170头65 kg左右的PIC杂交商品猪进行为期35d的对比饲养试验.试验采用5(日粮)×2(性别)的二因交叉分组设计.5种日粮如下对照组(C),其维生素E添加量为30mg·kg-1,铁、铜、锌、硒均用无机盐形式添加;维生素E组(VE)日粮在对照组的基础上将其中的维生素E添加量提高到200 mg·kg-1,其他不变;氨基酸螯合物组(OTM)日粮将对照组中的无机铁、铜、锌分别用有机铁、铜、锌替换,其他不变;有机硒组(OSe)日粮将对照组中的无机硒用有机硒替换,其他不变;维生素E与有极微量元素混合组(VE/OTM)的日粮在对照组的基础上将配合料中维生素E添加量提高到200 mg·kg-1,并将无机铁、铜、锌、硒分别用有机铁、铜、锌、硒替换,其他不变.试验结果表明①提高维生素E添加量至200mg·kg-1,对增加肌肉中的维生素E含量与校正pH值有极显著效果(P＜0.01);对改善肉色、降低滴水损失、提高嫩度和肌内脂肪含量虽未达到P＜0.05的显著水平,但均呈有益趋势.②用有机铁、铜、锌替代无机铁、铜、锌与提高维生素E添加量相比,使用效果除对肌肉中的维生素E含量外没有显著差别;但是二者与用有机硒替代无机硒相比,则除pH值外,一律呈现更佳趋势;用有机硒替代无机硒在pH值、滴水损失、肌内脂肪含量方面呈有利趋势,在肉色、嫩度呈不利趋势,但均未达到P＜0.05的显著水准.③统计结果显示日粮与性别的互作效应在各项指标上均不显著,但肉色在不同性别间差异显著(P＜0.05).据上述结果可以认为,提高维生素E的添加量或使用有机微量元素可以改善肉质.     

铜、维生素A及互作效应对肉仔鸡肠壁组织结构、肠道微生物和血清生长激素的影响

 【目的】研究日粮中添加铜和维生素A及互作效应对肉仔鸡小肠各段肠壁厚度和绒毛高度、盲肠主要微生物、血清生长激素（GH）的影响。【方法】采用4×2(Cu×VA)完全随机试验设计,日粮Cu水平为0、8、150、225 mg?kg-1,VA水平为1 500、5 000 IU?kg-1,生长阶段分为前期（0～4 w）和后期（4～7 w）。选用1 d艾维茵肉仔鸡448只,随机分为8组,每组4个重复,每重复14只鸡,公母比为1﹕1。【结果】①前期添加Cu（8 mg?kg-1）生产性能较好,后期不添加Cu生产性能较好。②添加Cu 225 mg?kg-1明显降低生长前期肉仔鸡回肠肠壁厚度,添加Cu 150 mg?kg-1使生长后期肉仔鸡小肠各段肠壁厚度明显较低,在整个生长期,高铜对绒毛高度无影响;日粮添加Cu 150 mg?kg-1显著提高盲肠乳酸杆菌和双歧杆菌数量,降低大肠杆菌数量,添加Cu 225 mg?kg-1显著降低盲肠乳酸杆菌和双歧杆菌数量,增加大肠杆菌数量;Cu 8 mg?kg-1组盲肠沙门氏菌数量最低。③日粮中添加VA5 000 IU?kg-1显著降低前期小肠各段肠壁厚度和后期空肠肠壁厚度、提高前期十二指肠绒毛高度;显著增加盲肠大肠杆菌、乳酸杆菌、前期沙门氏菌和双歧杆菌的数量;④Cu和VA交互作用显著影响前期回肠肠壁厚度、后期空肠肠壁厚度(P＜0.05);极显著影响前期十二指肠绒毛高度、后期十二指肠和回肠绒毛高度、前后期盲肠内乳酸杆菌、双歧杆菌、大肠杆菌和沙门氏菌数量(P＜0.01);⑤Cu、VA及互作对血清GH无影响(P＞0.05),前期GH平均水平高于后期。【结论】日粮添加Cu 150 mg?kg-1和VA 5 000 IU?kg-1有益于肉仔鸡小肠肠道形态和盲肠肠道菌群平衡;Cu和VA存在互作效应。     

饲喂水平对杂交肉羊(母)营养物质代谢及能量需要参数的影响

采用完全随机试验设计,将15只出生日期相近、体况良好、体重均匀的杂交母羊随机分成3组(每个处理5只羊),分别按自由采食(AL)、限饲70%(IR70)和限饲40%(IR40)3水平投喂试验饲粮,试验期26 d,连续两期试验。结果表明,饲喂水平对杜寒杂交母羊生长性能及营养物质采食量有极显著影响(P0.01),但对营养物质消化率无影响(P0.05);饲喂水平对杂交肉羊甲烷排放量、甲烷能及产热量均有极显著影响(P0.01);试验母羊绝食60 h时,FHP为0.20和0.24 MJ·kg~(-1)·W0.75,NEm为0.24和0.288 MJ·kg~(-1)·W0.75。文章旨在利用"开放式"呼吸测热装置研究杜寒杂交母羊营养物质代谢及能量需要参数,为肉羊科学饲养提供依据。     

不同水平维生素D3对扬州鹅仔鹅钙磷代谢和免疫机能的影响

【目的】研究在基础日粮中添加不同水平维生素D3（VD3）对仔鹅钙磷代谢和免疫机能的影响。【方法】将300只健康、体重均匀的28日龄扬州鹅公鹅随机分成5个处理组,每个处理组6个重复,每个重复10只。对照组饲喂基础饲粮,试验组分别饲喂添加500、1 000、2 000和4 000 IU•kg-1维生素D3的试验饲粮,饲养至10周龄。【结果】基础日粮中添加1 000 IU•kg-1的维生素D3显著提高了10周龄扬州鹅血清钙含量、胫骨钙含量、胫骨强度和血清免疫球蛋白IgG含量（P＜0.05）;添加2 000 IU•kg-1维生素D3显著提高了血清钙含量（P＜0.01）、胸腺指数和血清白细胞介素-4水平（P＜0.05）;但日粮维生素D3水平对血清磷含量和碱性磷酸酶活性影响不显著（P＞0.05）。【结论】日粮中添加适宜水平的维生素D3（1 000—2 000 IU•kg-1）有利于提高扬州鹅仔鹅的钙代谢和免疫机能。     

饲粮尿素添加水平对生长育肥牛生长性能和血液生化指标的影响

【目的】利用肉牛饲养试验研究饲粮尿素添加水平对生长育肥牛生长性能和血液生化指标的影响,为肉牛生产中合理添加尿素提供理论依据。【方法】选择60头利木赞×复洲杂交的F1公牛,随机分为6组,每组10头,分别接受1个尿素添加水平的饲粮处理。设置6个粗蛋白和代谢能值相近（14% CP,11.3 MJ•kg-1,DM基础）的饲粮处理,其中尿素添加量分别为0%（对照）、0.4%、0.8%、1.2%、1.6%和2.0%。试验期14周,其中预饲期1周,正试期13周。【结果】随尿素添加水平的提高,干物质摄入量（dry matter intake,DMI）无显著变化（P＞0.1）,但日增重呈线性规律显著下降（L,P＜0.05）,饲料转化效率（DMI/ADG（average daily gain））呈现线性规律显著上升（L,P＜0.05）。其中,尿素添加水平在0.8%以内未见日增重和饲料转化效率（DMI/ADG）有显著变化。提高饲粮尿素添加水平,血氨浓度线性上升（L,P＜0.001）;而血浆总蛋白和血浆尿素氮（plasma urea-N,PUN）浓度呈二次曲线规律升高（Q,P＜0.001）,其中血浆总蛋白和PUN浓度分别在1.50%和0.64%（%DM）尿素添加水平下出现拐点。提高饲粮尿素添加水平对谷丙转氨酶活性没有显著影响（P＞0.1）,但会导致谷草转氨酶活性呈线性升高（L,P＜0.001）。在反映肉牛应激状况的激素指标中,除肾上腺素外,肌酸激酶活性、去甲肾上腺素、皮质醇、皮质酮和醛固酮浓度等均呈显著的二次曲线规律上升或下降（Q,P＜0.05）;其中,上升或下降趋势的变化出现在0.8%-1.2%尿素添加水平。【结论】生长育肥牛饲粮中尿素添加水平在0.8%以内,或尿素氮占总氮比例在16%以内,可认为是适宜的安全添加水平。     

V_A对生长蛋鸭脂质过氧化作用及抗氧化机能的影响

研究日粮中不同VA水平(0、2250、5500、8250、12000和15000IU·kg-1)对生长蛋鸭脂质过氧化作用及抗氧化机能的影响。试验采用单因素随机区组试验设计,选用28日龄平均体重(0.45±0.01)kg的金定蛋鸭216只,随机分为6个处理组,试验期为42d。结果表明,日粮中添加不同水平的V(A2250、5500、8250、12000和15000IU·kg-1)均可显著提高试鸭血清及肝脏中GSH-Px活力和SOD活力(P<0.05);添加5500IU·kg-1和8250IU·kg-1的VA可显著提高试鸭血清及肝脏中T-AOC和降低脂质过氧化反应产物MDA的含量(P<0.05),但当VA添加量至12000IU·kg-1和15000IU·kg-1时,试鸭血清及肝脏中T-AOC有所下降,并且GSH-Px活力和SOD活力与5500IU·kg-1和8250IU·kg-1组相比也明显降低。因此,日粮中添加5500IU·kg-1和8250IU·kg-1VA能显著提高机体的抗氧化能力和降低机体的脂质过氧化水平,添加12000IU·kg-1和15000IU·kg-1水平不利于VA在生长蛋鸭上发挥其抗氧化作用。     

Effects of dietary yeast β-glucan on nutrient digestibility and serum profiles in pre-ruminant Holstein calves

This study aimed to investigate the effects of dietary supplementation of yeast β-glucan on the nutrient digestibility and serum profiles in pre-ruminant Holstein calves. Forty-two neonatal Holstein calves ((39.6±4.2) kg) were randomly allotted to six groups, and each was offered one of the following diets: a basal diet (control) or the basal diet supplemented with 25, 50, 75, 100 or 200 mg of yeast β-glucan kg–1 feed (dry matter basis). The basal diet consisted of a milk replacer and a starter feed. The trial lasted for 56 d. Two digestibility trials were conducted from d 14 to 20 and from d 42 to 48. Blood samples were collected on d 0, 14, 28 and 42 for serum profile analyses. On d 56, three calves from each group were slaughtered, and intestinal samples were collected to assess the villous height, crypt depth and mucosal thickness. Although feed intake was not affected by dietary treatment (P>0.05), the average daily gain (ADG) and gain-to-feed ratios were higher (P<0.05) for the calves fed 75 mg of yeast β-glucan kg–1 feed than those in the other groups. The supplementation of yeast β-glucan at 75 mg kg–1 feed increased the apparent digestibility of dry matter (DM), crude protein (CP), ether extract (EE), and phosphorus (P) (P<0.05) and the ratio of intestinal villous height to crypt depth (V/C) (P<0.05) when compared with the control group. No effects of yeast β-glucan on the serum concentrations of total protein (TP), albumin (ALB), serum urea nitrogen (SUN) and glucose (GLU) were observed (P>0.05). Compared with the control group, supplementation of yeast β-glucan decreased (P<0.05) the serum concentrations of triglycerides (TG) and total cholesterol (TC). The serum concentration of immunoglobulin G (IgG) and immunoglobulin M (IgM) increased quadratically (P<0.05), whereas the serum concentration of immunoglobulin A (IgA) was unaffected by dietary treatments (P>0.05). The supplementation of yeast β-glucan stimulated the enzymatic activity of alkaline phosphatase (ALP) (P<0.05) compared with the control group. The lysozyme (LYZ) concentration increased quadratically (P<0.05) with increasing yeast β-glucan levels. The results suggested that dietary supplementation of yeast β-glucan at 75 mg kg–1 feed improved nutrient digestibility, enhanced immunity by increasing the immunoglobulin concentration and stimulating ALP, and exerted no adverse effects on metabolism in pre-ruminant calves.     

Poultrygrow 250TM对宁都三黄鸡消化酶活性、营养物质消化率、抗热应激、免疫机能及生产性能的影响研究

选用健康的1日龄三黄鸡1200羽(公母各半),初生重接近,随机分为4组,每组5个重复,每个重复60羽(公母各半),分别为A1,A2,A3,A4。A1组饲喂常规蛋白质水平日粮;A2组饲喂低蛋白水平日粮(0~4周蛋白质含量低3%,5~12周蛋白质含量低5%);A3组日粮在A1组日粮的基础上添加125 mg/kg的Poultry-grow250TM;A4组日粮在A2组日粮的基础上添加125 mg/kg的Poultrygrow250TM。分别在4周龄、8周龄、12周龄3个阶段测定宁都三黄鸡十二指肠内容物淀粉酶和肌胃内容物蛋白酶活性、免疫器官指数、日增重、日采食量、饲料转化率;在6周龄和12周龄测定宁都三黄鸡日粮干物质消化率和氮的表观消化率、血清中丙二醛(MDA)含量、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-PX)活性;在6、8、10、12周龄时测定血清中总蛋白和球蛋白含量。结果表明:Poultrygrow250TM可提高宁都三黄鸡干物质消化率和氮的表观消化率;提高宁都三黄鸡的饲料转化率提高,特别是在生长发育期效果显著;提高三黄鸡抗热应激能力,降低由于热应激造成的生产性能的损失;提高蛋白质消化率,降低日粮蛋白质水平,节约蛋白质资源。     

Use of the N-alkanes to Estimate Intake,Apparent Digestibility and Diet Composition in Sheep Grazing on Stipa breviflora Desert Steppe

The application of n-alkane as markers to estimate herbage intake, apparent digestibility and species composition of diet consumed by grazing sheep was studied. Six local Mongolian sheep were used to determine dry matter (DM) intake, apparent DM digestibility and species composition of diet during summer, autumn and winter. Animals were orally dosed twice daily with n-alkane gelatin capsules containing 60 mg C₃₂-alkane as an external marker. Diet composition was estimated by comparing the odd-chain n-alkanes pattern profile (C₂₇-C₃₁) of the consumed plant species with the n-alkanes fecal concentrations of grazing animals, using a non-negative least squares algorithm called EATWHAT software package. The alkane pair C₃₂:C₃₃ and C₃₃ alkane were used to estimate DM intake and diet apparent DM digestibility, respectively. The results showed that daily dry matter intake of the sheep were 1.77, 1.61 and 1.18 kg d⁻¹ in summer, autumn and winter, respectively. Apparent DM digestibility, crude protein (CP), metabolizable energy (ME) and neutral detergent fiber (NDF) intake of diet consumed by sheep decreased significantly (P<0.01) from summer to winter, with no evident changes in ADF and ADL intake. Diet composition indicated Artemisia frigida Willd was the most dominant diet component, contributed 79.68, 68.12 and 86.26% of sheep's diets in summer, autumn and winter, respectively. Cleistogenes songorica Ohwi and Convolvulus ammannii Desr were the important components of the diet. Although Stipa breviflora Griseb is one of the main plant species in the study area, the sheep rarely choosed it. The study indicated that CP and ME in diet consumed by sheep were deficient in winter. Therefore, appropriate supplementation strategies should be indispensable during this period.     

日粮Cu、Fe、Zn、Mn水平对肉鸡生产性能的影响

对640羽体质量均匀的1日龄爱拔益加(AA+)肉鸡,采用正交优化设计,通过饲养试验研究同一基础日粮(基础日粮Cu、Fe、Zn、Mn实测含量,1~21日龄分别为12.2、185.7、15.8和29.4 mg/kg,22~42日龄分别为14.3、159.2、28.4和46.5 mg/kg)中添加不同水平的Cu(0、10、20、30 mg/kg)、Fe(0、50、100、200 mg/kg)、Zn(0、30、60、120 mg/kg)和Mn(0、40、80、160 mg/kg)对肉鸡生产性能的影响。结果显示,日粮Cu、Fe、Zn、Mn的不同组合显著影响1~21 d日增体质量,Fe的添加水平是影响1~21 d肉鸡日增体质量的决定因素。日粮Cu、Fe、Zn、Mn组合不影响22~42 d和1~42 d肉鸡日增体质量、采食量和料体质量比,添加Zn、Mn降低全期饲料转化率。结果表明,在本试验的16个微量元素添加组合中,1~21 d肉鸡Cu、Fe、Zn、Mn的最佳添加水平分别为30、100、30、160 mg/kg;22~42 d肉鸡日粮中不需要额外添加Cu、Fe、Zn、Mn。     

Effects of Different Energy Levels on Nutrient Utilization and Serum Biochemical Parameters of Early-Weaned Calves

Current study was performed to investigate the effects of different energy levels on nutrient digestion metabolism and serum biochemical parameters of early-weaned calves. Twelve neonatal Holstein calves were selected and assigned randomly to receive 1 of 3 treatments that contained 18.51, 19.66 and 20.80 MJ kg^-1 gross energy, respectively （n=4 per treatment）. Digestion and metabolism trials were carried out in 5 phases （12-20, 22-30, 32-40, 42-50, and 52-60 d of age）. At the same time, blood metabolites were determined at 21, 31, 41, 51, and 61 d of age prior to morning feeding. The results indicated that either dry matter （DM）, organic matter （OM） and gross energy （GE） apparent digestibility or N and P retention tended to increase as age advanced; the average value of DM and OM apparent digestibility and Ca retention in high-energy treatment was significantly lower than that of other groups （P 〈 0.05）; there were no significant differences in the concentration of serum glucose, triglyceride and urea N among treatments, whereas a significant effect of age was found on the level of triglyceride （P 〈 0.05）. To sum up, medium-energy milk replacer seems to be more beneficial for GE digestibility and N utilization, whereas low-energy milk replacer appears to be more rewarding for Ca and P utilization.