植酸酶、柠檬酸和碳酸化合物酶对肉鸡生长性能和养分利用率的影响

文章旨在研究低磷、低钙水平日粮添加植酸酶、柠檬酸和碳水化合物酶对1~21 d肉鸡生长性能及养分消化率的影响。试验选择1日龄肉仔鸡576只,随机分为6组,每组4个重复,每个重复24只鸡。试验共分为6种日粮,阳性对照组日粮(正常钙磷水平)、阴性对照日粮(低磷、低钙)、阴性对照日粮+600 IU/kg植酸酶,阴性对照日粮+600 IU/kg植酸酶+5 g/kg柠檬酸,阴性对照日粮+600 IU/kg植酸酶+500 mg/kg复合碳水化合物酶,阴性对照日粮+600 IU/kg植酸酶+5 g/kg柠檬酸+500 mg/kg复合碳水化合物酶。试验共开展21 d。结果显示:阳性对照组肉鸡日增重和采食量显著高于阴性对照组(P<0.05);植酸酶组添加碳水化合物酶较单独添加植酸酶组显著提高了肉鸡的日增重(P<0.05);植酸酶+碳水化合物酶较阴性对照组显著改善了料肉比(P<0.05)。阳性对照组较阴性对照组显著提高肉鸡胫骨灰分含量(P<0.05);植酸酶组显著提高了总磷、有效磷和植酸磷的回肠表观消化率(P<0.05),同时植酸酶组添加柠檬酸或碳水化合物酶进一步提高了总磷和植酸磷的回肠表观消化率(P<0.05)。阴性对照组添加植酸酶显著提高了表观代谢能及干物质、总能、氮和总磷的表观沉积量(P<0.05),而植酸酶组添加碳水化合物酶提高了干物质和总磷表观沉积量(P<0.05)。结论:在本试验条件下,低磷、低钙水平日粮添加植酸酶和碳水化合物酶改善了肉鸡生长性能、提高了营养物质的消化率和沉积量,而植酸酶日粮添加柠檬酸可以改善营养物质消化率和沉积量。     

植酸酶对肉鸡生产性能及饲料养分消化率的影响

试验选取1日龄AA肉鸡600只,随机分为6个处理,每个处理5个重复。试验基础日粮为玉米-豆粕型,1～3周龄和4～6周龄正、负对照组调整有效磷水平分别为0.43%、0.23%和0.34%、0.14%,负对照组基础上添加不同水平的植酸酶与负对照组一起形成0、250、500、750、1 000 U/kg 5个梯度。结果表明:日增重与植酸酶水平之间存在显著二次曲线相关(P<0.05);随着植酸酶添加水平的增加,胫骨强度有呈二次曲线增加的趋势(P<0.1)。进行3 d代谢试验,植酸酶不仅与粪中磷含量存在显著二次曲线相关(P<0.05),而且与粪中钙含量也有二次性响应的趋势(P<0.1)。从单个处理来看,在低磷日粮中添加500 U/kg植酸酶提高日增重和改善胫骨强度最为显著。综合各项指标二次曲线统计分析的结果,本试验日粮基础上添加750 U/kg植酸酶最为科学合理。     

饲粮卵磷脂添加水平对肉鸡生长性能、屠宰性能、肝脏营养成分及肝脏和血清生化指标的影响

本试验旨在研究饲粮卵磷脂添加水平对肉鸡生长性能、屠宰性能、肝脏营养成分及肝脏和血清生化指标的影响。选取体重一致的1日龄爱拔益加(AA)肉仔鸡500只,随机分成5个组,每组10个重复,每个重复10只鸡。对照组饲喂基础饲粮,试验组在基础饲粮中分别添加500、1000、1500和2000 mg/kg卵磷脂。试验期42 d。结果表明:1)随着饲粮卵磷脂添加水平的增加,21和42日龄肉鸡平均体重呈二次曲线升高(P<0.05)。2)随着饲粮卵磷脂添加水平的增加,42日龄肉鸡半净膛率和全净膛率呈线性和二次曲线升高(P<0.05),42日龄肉鸡腿肌率呈线性升高(P<0.05)。3)随着饲粮卵磷脂添加水平的增加,21日龄肉鸡新鲜样本基础和干物质基础上肝脏有机物含量呈线性和二次曲线升高(P<0.05或P<0.01),42日龄肉鸡新鲜样本基础和干物质基础上肝脏有机物和粗脂肪含量均呈线性和二次曲线升高(P<0.05或P<0.01)。4)随着饲粮卵磷脂添加水平的增加,21日龄肉鸡肝脏总胆固醇含量呈线性升高(P<0.05),42日龄肉鸡肝脏甘油三酯含量呈线性和二次曲线升高(P<0.01)。5)与对照组相比,饲粮添加1000、1500和2000 mg/kg卵磷脂显著降低了21和42日龄肉鸡血清甘油三酯含量(P<0.05),饲粮添加2000 mg/kg卵磷脂显著降低21和42日龄肉鸡血清尿素氮含量(P<0.05)。随着饲粮卵磷脂添加水平的增加,21日龄肉鸡血清低密度脂蛋白、甘油三酯和总胆固醇含量呈线性降低(P<0.05),42日龄肉鸡血清甘油三酯含量呈线性和二次曲线降低(P<0.05)。由此可见,饲粮添加卵磷脂能够提高肉鸡生长性能和屠宰性能,调节肝脏和血清脂质代谢,降低血清尿素氮含量。以肉鸡平均体重为判断指标,推荐1~21日龄和22~42日龄肉鸡基础饲粮中卵磷脂添加水平分别为952和1246 mg/kg。     

维生素A对肉鸡生长性能、免疫及抗氧化功能的影响

本试验旨在研究饲粮中添加不同水平维生素A对肉鸡生长性能、免疫及抗氧化功能的影响。采用单因子完全随机试验设计,选用1日龄健康爱拔益加(AA)肉鸡240只(公母各占1/2),随机分为5个组(在玉米-豆粕型饲粮中分别添加3 000、6 000、15 000、30 000和45 000 IU/kg维生素A),每个组6个重复,每个重复8只鸡,试验期42 d。结果表明:1)饲粮中添加不同水平维生素A对22~42日龄肉鸡的平均日增重(ADG)、平均日采食量(ADFI)及1~42日龄肉鸡的ADFI均有显著影响(P<0.05),对22~42日龄肉鸡的料重比(F/G)的影响有显著的趋势(0.05≤P<0.10),且22~42日龄和1~42日龄肉鸡的ADFI以及1~42日龄肉鸡的F/G随饲粮维生素A添加水平的增加均呈线性升高(P<0.05或0.05≤P<0.10),3 000 IU/kg组肉鸡增重效果较差,6 000和15 000 IU/kg组肉鸡增重高且F/G低,30 000和45 000 IU/kg组肉鸡ADFI较高、F/G不同程度升高。2)饲粮添加不同水平维生素A对21日龄血清白细胞介素-1(IL-1)和42日龄血清IL-1、白细胞介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)含量有显著影响(P<0.05),对42日龄血清白细胞介素-2(IL-2)含量的影响有显著的趋势(0.05≤P<0.10),其中3 000、6 000和45 000 IU/kg组血清免疫因子含量较低,15 000 IU/kg组较高。3)饲粮添加不同水平维生素A对21日龄血清谷胱甘肽过氧化物酶(GSH-Px)活性和42日龄血清GSH-Px、过氧化氢酶(CAT)活性有显著影响(P<0.05),且21日龄血清丙二醛(M DA)含量随饲粮维生素A添加水平的增加呈线性升高趋势(0.05≤P<0.10),42日龄血清MDA含量、总超氧化物歧化酶(T-SOD)活性随饲粮维生素A添加水平的增加分别呈显著的一次线性和二次曲线升高(P<0.05),其中45 000 IU/kg组血清MDA含量较高且T-SOD活性较低。综上,本试验条件下添加6 000和15 000 IU/kg的维生素A可使肉鸡获得较好的生长性能,且15 000 IU/kg维生素A可满足肉鸡免疫和抗氧化需要,而添加水平增至30 000和45 000 IU/kg时肉鸡生长性能和免疫抗氧化机能均有降低趋势。     

日粮中高剂量植酸酶对肉鸡生长性能、骨骼矿化和钙磷沉积的影响

试验旨在研究含25-羟基维生素D3(25-OH-D3)低磷日粮中添加高剂量植酸酶对1~42日龄肉鸡生长性能、骨骼矿化和钙磷沉积率的影响。将250只1日龄肉鸡公雏随机分成5个处理,每个处理5个重复,每重复10只。1个对照组:非植酸磷(NPP)含量为0.45%/0.35%;4个试验组按照2×2因子设计试验:2个NPP含量(1~21日龄,NPP含量分别为0.35%和0.25%;22~42日龄,NPP含量分别为0.25%和0.15%),植酸酶2个添加水平为1 000 IU/kg和10 000 IU/kg。结果显示:(1)与日粮中NPP含量0.35%/0.25%相比,NPP含量为0.25%/0.15%时,42日龄肉鸡体增重、血浆无机磷浓度、股骨和胫骨灰分重量、钙含量以及跖骨直径和磷含量显著降低(P<0.05),31~34日龄肉鸡钙沉积率和11~14日龄肉鸡磷沉积率显著提高(P<0.05)。(2)与日粮中植酸酶添加1 000 IU/kg相比,植酸酶添加10 000 IU/kg时,42日龄肉鸡体增重、采食量、血浆无机磷浓度、股骨重量和灰分重量、胫骨和跖骨长度显著提高(P<0.05),11~14日龄肉鸡钙磷沉积率显著提高(P<0.05)。(3)与日粮中NPP含量0.45%/0.35%相比,日粮中0.35%/0.25%NPP+1 000 IU/kg植酸酶或0.25%/0.15%NPP+10 000 IU/kg植酸酶时,肉鸡生长性能和骨骼矿化(除跖骨磷含量外)未受到显著影响(P>0.05)。综上所述,1~42日龄肉鸡日粮中NPP含量为0.35%/0.25%时,植酸酶适宜添加量为1 000 IU/kg;NPP含量为0.25%/0.15%时,植酸酶适宜添加量为10 000 IU/kg。     

肉鸡玉米型日粮添加高剂量植酸酶对其养分利用的影响

文章旨在研究肉鸡饲粮中植酸酶水平从1000 FTU/kg(行业推荐水平)提高到2500 FTU/kg(超剂量水平)对肉鸡养分回肠表观消化率系数和氮平衡校正表观代谢能值的影响。试验选择360只1日龄雄性肉仔鸡,随机分为3组,每组4个重复,每个重复30只肉鸡。试验1~14 d饲喂基础日粮(前期料),在15~21 d期间饲喂3种日粮,即正对照日粮(不含植酸酶)、负对照日粮(1000 FTU/kg植酸酶),植酸酶组日粮(2500 FTU/kg植酸酶)。负对照组日粮除钙和非植酸磷含量降低1.80 g/kg和1.50 g/kg外,其余营养指标均与正对照组日粮相同。结果显示,正对照组日粮的总能和粗蛋白质回肠表观消化系数显著高于负对照组(P <0.05)。正对照组日粮中淀粉、钙、磷的回肠表观消化系数与负对照组日粮无显著差异(P> 0.05)。正对照组日粮的氮校正表观代谢能显著低于负对照组日粮(13.34 MJ/kg和14.46 MJ/kg,P <0.05)。负对照组日粮中植酸酶水平从1000 FTU/kg升高至2500 FTU/kg,导致总能和粗蛋白质回肠表观消化系数分别升高2.5%和7.1%(P <0.05),且磷有显著升高的趋势(10.4%,P=0.08)。此外,负对照组日粮中植酸酶水平从1000 FTU/kg升高至2500 FTU/kg时对淀粉回肠表观消化系数和日粮的氮校正表观代谢能值无显著影响(P> 0.05)。综上所述,日粮超剂量植酸酶水平(≥2500 FTU/kg)在改善玉米能量、蛋白质和磷在回肠消化率的效率要优于肉鸡行业推荐水平。     

植物提取物对肉鸡生长性能、养分消化率及盲肠微生物组成的影响

文章旨在研究日粮添加植物提取物替代抗生素对1～42 d肉鸡生长性能、养分消化率及盲肠微生物组成的影响。试验选择1日龄商品肉鸡840只,随机分为5组,每组6个重复,每个重复28只鸡。对照组饲喂常规玉米-豆粕型日粮,抗生素组在对照组日粮中添加2 mg/kg阿维霉素,植物提取物组分别在对照组日粮中添加50、100和200 mg/kg植物提取物,试验从1 d开展到42 d。结果显示:随着植物提取物添加水平的升高,1～14 d肉鸡采食量表现为显著线性降低(P 0.05),29～42 d肉鸡日增重表现为显著线性和二次曲线关系(P 0.05)。日粮植物提取物添加水平对试验全期料重比的影响表现为显著线性关系(P 0.05),对采食量的影响表现为显著二次曲线关系(P 0.05)。与其他组相比,抗生素组显著提高了粗脂肪的回肠表观消化率和肠道总消化率(P 0.05),同时显著提高了灰分的肠道总消化率(P 0.05)。50 mg/kg植物提取物组较对照组显著提高了代谢能消化率(P 0.05)。与抗生素组相比,100和200 mg/kg植物提取物组显著降低了14 d肉鸡盲肠大肠杆菌数量(P 0.05);100和200 mg/kg植物提取物组较对照组显著提高了盲肠乳酸杆菌、双歧杆菌和革兰氏阳性菌含量(P 0.05)。结果表明:玉米-豆粕型日粮中添加100和200 mg/kg植物提取物可以替代抗生素来改善1～42 d肉鸡的料重比。日粮添加50 mg/kg植物提取物对有机物和代谢能的肠道总消化率具有提高作用。     

维生素A添加水平对22～42日龄黄羽肉鸡生长性能、血清和肝脏维生素A含量及抗氧化能力的影响

本试验旨在研究饲粮中添加不同水平维生素A对22～42日龄黄羽肉鸡生长性能、血清和肝脏维生素A含量及抗氧化能力的影响。选用22日龄快长型岭南黄羽肉公鸡1 440只,根据体重均衡原则随机分为6个处理,每个处理6个重复,每个重复40只。各处理维生素A添加水平分别为0(对照组)、750、1 500、3 000、6 000、12 000 IU/kg。试鸡自由采食与饮水,饲养21 d。结果表明:1)饲粮添加维生素A显著提高试鸡42日龄体重和平均日增重(P<0.05),并显著降低料重比(P<0.05),添加维生素A 1 500、3 000 IU/kg显著提高试鸡平均日采食量(P<0.05)。2)随维生素A添加水平升高,试鸡血清、肝脏维生素A含量显著提高(P<0.05)。添加维生素A 12 000 IU/kg组血清和肝脏维生素A含量显著高于其他各组(P<0.05),添加维生素A 3 000、6 000 IU/kg组血清维生素A含量显著高于除添加维生素A 12 000 IU/kg组外的其他各组(P<0.05),添加维生素A 6 000 IU/kg组肝脏维生素A含量显著高于除添加维生素A 12000 IU/kg组外的其他各组(P<0.05)。3)饲粮中添加维生素A 1 500、3 000、6 000 IU/kg可显著提高试鸡血清谷胱甘肽过氧化物酶(GSH-Px)活力(P<0.05),添加维生素A可显著提高肝脏GSH-Px活力(P<0.05);添加维生素A 1 500、3 000、6 000、12 000 IU/kg可显著降低血清丙二醛(MDA)含量(P<0.05),添加维生素A 3 000 IU/kg可显著降低肝脏MDA含量(P<0.05)。结果提示,饲粮添加维生素A 3 000～6 000 IU/kg能维持血清维生素A含量稳定,提高机体抗氧化能力,从而促进22～42日龄黄羽肉鸡生长。     

25-OH-VD_3和植酸酶对肉鸡生长性能及血清生化指标的影响

研究旨在探讨植酸酶与25-OH-VD3配合使用对肉鸡生长性能及血清生化指标的影响。试验选取岭南黄羽肉鸡780只,集中育雏7日之后,随机分为5个处理,每个处理6个重复,每重复26只。5个处理分别为:正对照组、负对照组、负对照组+500 U/kg植酸酶、负对照组+70μg/kg 25-OH-VD3、负对照组+500 U/kg植酸酶+70μg/kg 25-OH-VD3。其中负对照组钙、磷水平分别比正对照组降低0.20%、0.12%。饲养试验分为三个阶段:8~21 d、22~36 d、37~58 d。统计各阶段肉鸡的始重、末重、平均日增重、平均日采食量和耗料增重比等生产性能。21、36、58 d时,每个重复挑取2只试验鸡屠宰,采集血清用于测定血钙、血磷和血清碱性磷酸酶(ALP)。结果表明:添加500 U/kg的植酸酶,其各期平均日增重、料重比都好于负对照组(P>0.05);在低钙、磷水平肉鸡日粮添加70μg/kg 25-OH-VD3对不同阶段的肉鸡生产性能均有一定程度的提高,尤其是22～36日龄肉鸡的平均日增重显著高于正、负对照组(P<0.05);但是,在低钙磷日粮配合使用植酸酶和25-OH-VD3未呈现出加和效应。     

低蛋白质饲粮添加载锌蒙脱石对肉鸡生长性能、免疫器官发育和肠道组织形态的影响

本试验旨在研究低蛋白质饲粮添加载锌蒙脱石(Zn-MMT)对肉鸡生长性能、免疫器官发育和肠道组织形态的影响。随机选择1日龄健康科宝公雏288只,按体重一致原则随机分成6个组,每组6个重复,每个重复8只鸡。对照组饲喂玉米-豆粕型低蛋白质基础饲粮,正对照组[硫酸锌(ZnSO 4)组]饲喂低蛋白质基础饲粮+40 mg/kg ZnSO 4,4个试验组分别在低蛋白质基础饲粮中添加20、40、60和80 mg/kg Zn-MMT(均以锌含量计算)。试验鸡自由采食和饮水,试验期为42 d。结果表明:1)与对照组和ZnSO 4组相比,低蛋白质饲粮添加60和80 mg/kg Zn-MMT显著降低肉鸡1~21日龄平均日增重(ADG,P<0.05),添加80 mg/kg Zn-MMT显著提高肉鸡1~21日龄料重比(F/G,P<0.05);添加Zn-MMT对肉鸡22~42日龄和1~42日龄ADG、平均日采食量和F/G以及1~21日龄ADG无显著影响(P>0.05)。2)与对照组相比,低蛋白质饲粮添加Zn-MMT对肉鸡21和42日龄免疫器官指数无显著影响(P>0.05);但与ZnSO 4组相比,低蛋白质饲粮添加Zn-MMT显著提高肉鸡21日龄胸腺指数和法氏囊指数(P<0.05),且添加80 mg/kg Zn-MMT显著提高肉鸡42日龄胸腺指数(P<0.05)。3)与对照组相比,低蛋白质饲粮添加20和60 mg/kg Zn-MMT显著提高肉鸡42日龄腿比率(P<0.05);与ZnSO 4组相比,低蛋白质饲粮添加Zn-MMT对肉鸡屠宰性能无显著影响(P>0.05)。4)与对照组相比,低蛋白质饲粮添加40和60 mg/kg Zn-MMT显著降低肉鸡十二指肠隐窝深度(CD,P<0.05),且添加60 mg/kg Zn-MMT显著降低肉鸡空肠CD(P<0.05);添加20 mg/kg Zn-MMT显著降低肉鸡回肠CD(P<0.05),并显著提高肉鸡回肠绒毛高度(VH)/CD(V/C)值(P<0.05);同时,添加80 mg/kg Zn-MMT显著降低肉鸡空肠V/C值(P<0.05)。与ZnSO 4组相比,低蛋白质饲粮添加20 mg/kg Zn-MMT显著提高肉鸡回肠V/C值(P<0.05),并显著降低回肠CD(P<0.05);添加40 mg/kg Zn-MMT显著提高肉鸡空肠VH(P<0.05),并显著降低肉鸡十二指肠CD(P<0.05);添加20和60 mg/kg Zn-MMT显著降低肉鸡空肠CD(P<0.05);添加20、40和60 mg/kg Zn-MMT显著提高肉鸡空肠V/C值(P<0.05)。综上所述,在低蛋白质饲粮中添加Zn-MMT对肉鸡后期生长性能无显著影响,但与添加ZnSO 4相比,可显著提高肉鸡免疫器官指数,提高小肠VH和V/C值,降低小肠CD,促进肉鸡肠道发育。     

Evaluation of the safety of daily administration of capromorelin in cats

Capromorelin is a ghrelin receptor agonist that is FDA approved for appetite stimulation in dogs. The objective of this study was to evaluate the safety of daily oral administration of capromorelin to cats over a range of doses and for an extended period. Two randomized, controlled studies were conducted: in Study 1, cats (n = 6 per group) received placebo or capromorelin at a dose of 9, 15, 30 or 60 mg/kg once daily for 14 days; and in Study 2, cats received capromorelin at 6 mg/kg (n = 8) or placebo (n = 4) once daily for 91 days. Cats were evaluated using clinical observations and clinical pathology test results for both studies, with the addition of postmortem examination in Study 1 and measurements of growth hormone and insulin‐like growth factor 1 in Study 2. Abnormal clinical observations were limited to emesis, hypersalivation, lethargy/depression, head shaking and lip smacking, which occurred more frequently in the capromorelin‐treated groups than in the placebo group. There were no clinically relevant differences in clinical pathology test results between the capromorelin and placebo groups in either study.     

不同青贮玉米品种抗病性评价

对10个青贮玉米品种自然发病情况进行调查,并采用病级分类方法对抗病性分类。结果表明:对锈病表现抗性和中抗的品种有3个和5个,分别占供试品种的30%和50%;对大斑病表现抗性和中抗的品种有4个和5个,分别占供试品种的40%和50%;对褐斑病表现抗性和中抗的品种有6个和3个,分别占供试品种的60%和30%;对小斑病表现抗性和中抗的品种有6个和3个,分别占供试品种的60%和30%。多数品种对青贮玉米4种病害抗性表现较好,可从青贮玉米供试材料中选用优良抗病材料用于四川地区种植。     

Evaluation of Oxygen-dependent Immunodefences of the Polymorphonuclear Cells of Some Tropical Ruminants

Activation of polymorphonuclear cells (PMNs) leads to the formation of superoxide, which is in turn dismutated to H₂O₂ by superoxide dismutase (SOD) and is partly responsible for oxygen-dependent microbicidal activity. However, no comparative information is available on the effect of SOD inhibition before PMN activation to allow simulation of the SOD defects that are known to occur in some ruminants. This paper attempts to examine the degranulative and phagocytic responses in buffalo, cattle and goat PMNs exposed to diethyldithiocarbamate, a known SOD inhibitor. The activity of glutathione peroxidase and reductase was increased in the presence of SOD inhibitor. On activation, H₂O₂ production increased significantly (p<0.01), while SOD inhibition before the activation of PMNs caused a significant decline in the production of H₂O₂ (p<0.05) in all the species studied. There was a significant increase (p<0.05) in the phagocytosis of Candida albicans spores by buffalo PMNs activated with opsonized zymosan. Activation of bovine PMNs after exposure to the SOD inhibitor resulted in a significant decline (p<0.05) in phagocytic activity; in the other species, the two values only approached significance. Among the activators, opsonized zymosan caused a significant increase in phagocytic activity as compared to lipopolysaccharide, particularly in the PMNs of buffaloes (p<0.05). Increased fungicidal activity (p<0.05) occurred with opsonized zymosan-activated PMNs of all the species studied. The fungicidal activity was found to decline in PMNs exposed to SOD inhibitor before activation (p<0.05). Interestingly, the phagocytic activity of caprine PMNs was found to be lower than that of PMNs from cattle (p<0.05).     

Effect of dietary stable isotopic ratios of carbon and nitrogen on the extent of their incorporation into tissues of rats

This study was conducted to investigate the effect of different dietary ratios of ¹³ C to ¹² C or ¹⁵ N to ¹⁴ N on their relative incorporation into tissues. Eighty male rats were used in two 21-day feeding trials in which they were fed diets with either high δ¹³C levels (δ¹³C = −13.89‰ and δ¹⁵N = 2.37‰ in experiment 1 and δ¹³C = −19.34‰ and δ¹⁵N = 4.73‰ in experiment 2) or low δ¹³C levels (δ¹³C = −17.90‰ and δ¹⁵N = 3.08‰ in experiment 1 and δ¹³C = −21.76‰ and δ¹⁵N = 0.53‰ in experiment 2), meanwhile, the dietary δ¹⁵N levels were designed to two ranks. Blood, liver, adipose and muscle tissues were collected on day 0, 3, 7, 14, and 21 for determination of ¹³ C, ¹² C, ¹⁵ N and ¹⁴ N isotopes. Rat growth rate, antioxidant capacity and metabolic parameters were also assessed. The results indicate that adipose tissue tend to deplete ¹³ C before the stable isotopic ratios achieved final equilibrium. Therefore, feeds with different isotopic signatures had different incorporation rates into tissues. Low dietary ¹³ C levels decreased tissue δ¹³C values whereas high dietary ¹³ C levels did not alter tissue δ¹³C values during the 21-d experiment. Blood δ¹⁵N values were a reliable parameter in assessing the relative contribution of dietary nitrogen to tissues. This study revealed a relationship between dietary isotopic signatures and their incorporation rates into rat tissues. However, more studies are needed to illustrate the mechanism through which dietary isotopic ratios influence the extent of isotopic incorporation into the tissues.     

Lack of postexposure analgesic efficacy of low concentrations of eugenol in zebrafish

Objective

To test the postexposure analgesic efficacy of low doses of eugenol in zebrafish.

氮对千日红试管苗生长和开花诱导的影响

本文以千日红组培苗为试验材料,研究培养基中氮形态及含量对千日红试管苗生长和开花诱导的影响。结果表明,1)相对于铵态氮(NH₄⁺),硝态氮(No₃^-)作为唯一氮源更有利于千日红试管苗生长和开花诱导,但千日红在NH₄⁺和NO₃^-同时存在的培养基中表现最佳。2)在20 mmol/LNH₄⁺(NO₃^-)和5 mg/L PP₃₃₃存在的条件下,试管苗生长基本随着培养基中NO₃^-(NH₄⁺)含量的增加而增加,并在含40 mmol/L NO₃^-+20 mmol/L NH₄⁺(即MS培养基中氮含量)的培养基中株高达到最大值5.91 cm;而叶片数和开花率则随着培养基中NH₄⁺和NO₃^-含量的增加呈现先增加后下降的趋势,并在20 mmol/L NO₃^-+5 mmol/LNH₄⁺培养基中达到最大值,分别为10.7片/株和38.89%。3)氮含量及形态配比结果表明,千日红试管苗开花率在培养基中氮总量为5 mmol/L、NO₃^-/NH₄⁺为4/1时达到最大值39.95%,而株高和叶片数在氮总量为35 mmol/L,NO₃^-/NH₄⁺为4/1时达到最大值8.52 cm和13.38片/株。千日红试管苗开花率与培养基中NO₃^-/NH₄⁺显著正相关,而与氮总量及株高之间显著负相关。此外,培养基中氮含量及形态配比还显著影响无菌苗根系生长。     

Pharmacokinetics of three formulations of vitacoxib in horses

The pharmacokinetic properties of three formulations of vitacoxib were investigated in horses. To describe plasma concentrations and characterize the pharmacokinetics, 6 healthy adult Chinese Mongolian horses were administered a single dose of 0.1 mg/kg bodyweight intravenous (i.v.), oral paste, or oral tablet vitacoxib in a 3-way, randomized, parallel design. Blood samples were collected prior to and at various times up to 72 hr postadministration. Plasma vitacoxib concentrations were quantified using UPLC-MS/MS, and pharmacokinetic parameters were calculated using noncompartmental analysis. No complications resulting from the vitacoxib administration were noted on subsequent administrations, and all procedures were tolerated well by the horses throughout the study. The elimination half-life (T_1/2λz) was 4.24 ± 1.98 hr (i.v.), 8.77 ± 0.91 hr (oral paste), and 8.12 ± 4.24 hr (oral tablet), respectively. Maximum plasma concentration (C_max) was 28.61 ± 9.29 ng/ml (oral paste) and 19.64 ± 9.26 ng/ml (oral tablet), respectively. Area under the concentration-versus-time curve (AUC_last) was 336 ± 229 ng hr/ml (i.v.), 221 ± 94 ng hr/ml (oral paste), and 203 ± 139 ng hr/ml, respectively. The results showed statistically significant differences between the 2 oral vitacoxib groups in T_max value. T_1/2λz (hr), AUC_last (ng hr/ml), and MRT (hr) were significantly different between i.v. and oral groups. The longer half-life observed following oral administration was consistent with the flip-flop phenomenon.     

Determination of optimal dietary selenium levels by full expression of selenoproteins in various tissues of broilers from 1 to 21 d of age

The current NRC dietary selenium (Se) requirement (0.15 mg/kg) of broilers is primarily based on growth performance data reported in 1986. Our study aimed to determine optimal dietary Se levels of broilers fed a practical corn-soybean meal diet for the full expression of selenoproteins in various tissues. A total of 384 one-d-old male broilers (n = 8 replicates/diet) were fed a basal corn-soybean meal diet or the basal diet supplemented with 0.1, 0.2, 0.3, 0.4 or 0.5 mg Se/kg in the form of Na₂SeO₃ for 21 d. Regression analysis was conducted to evaluate the optimal dietary Se levels using broken-line, quadratic or asymptotic models. The activity of glutathione peroxidase (GPX) in the plasma, liver, kidney and pancreas, iodothyronine deiodinase (DIO) in the plasma, liver and pancreas, and thioredoxin reductase (Txnrd) in the liver and pancreas, the mRNA levels of Gpx1, Gpx4, Dio1, selenoprotein (Seleno) h, Selenop and Selenou in the liver, Gpx4, Dio1, Txnrd1, Txnrd2, Selenoh, Selenop and Selenou in the kidney, and Gpx1, Gpx4, Selenoh and Selenou in the pancreas, and the protein levels of GPX4 in the liver and kidney of broilers were influenced (P < 0.05) by added Se levels, and increased quadratically (P < 0.05) with the increase of added Se levels. The estimates of optimal dietary Se levels were 0.07 to 0.36 mg/kg based on the fitted broken-line, quadratic or asymptotic models (P < 0.001) of the aforementioned selenoprotein expression in the plasma, liver and kidney, and 0.09 to 0.46 mg/kg based on the fitted broken-line models (P < 0.001) of the aforementioned selenoprotein expression in the pancreas. The results indicate that the optimal dietary Se levels would be 0.36 mg/kg to support the full expression of selenoproteins in the plasma, liver and kidney, and 0.46 mg/kg to support the full expression of selenoproteins in the pancreas of broilers fed a practical corn-soybean meal diet from 1 to 21 d of age.     

Influence of fibre and betaine on development of the gastrointestinal tract of broilers between hatch and 14 d of age

An experiment was designed to determine the influence of fibre and betaine on the development of the intestine, liver and pancreas of broilers from hatch to 14 d of age. A total of 250-day-old Cobb 500 male broilers were allocated to 16 cages with 15 broilers each. Treatments were arranged in a 2 × 4 factorial design, consisting of 2 feed formulations (low and high fibre diets) and 4 levels of betaine (0, 1, 3 or 5 kg/t). At hatch, 10 birds in total were euthanised, and samples of the liver, pancreas, yolk sac and intestine were collected for reference of the analysed parameters before the start of the trial. On d 4, 9 and 14, 5 birds per cage (10 birds per treatment) were selected, euthanised and treated as the same as the birds at hatch. Villus height and width and crypt depth were determined on the duodenum samples, and absorptive area was calculated. The number of enterocytes in mitosis at the villus was determined by a positive reaction to antibody for Ki67 protein, and fused villus was evaluated visually. The relative weight of the yolk sac reduced (P < 0.05) as birds aged while the intestine and liver reached a maximum (P < 0.05) at around d 4 and the pancreas at d 9. Birds fed the high fibre diet had greater feed intake, lower relative weight of the pancreas and higher villus (P < 0.05) than birds fed the low fibre diet. Villus width increased (P < 0.05) at 4 d of age, and this was associated with fused villus. Betaine inclusion reduced (P < 0.05) villus width, increased (P < 0.05) villus size and absorptive area, and reduced (P < 0.05) the number of enterocytes with positive reaction for the antibody Ki-67. Betaine inclusion reduced the width and increased the absorptive area and the villus height of the duodenum of birds up to 14 d of age. The higher fibre diet increased feed intake and villus height, yet reduced pancreas relative weight, while not affecting body weight gain. This response was possibly due to a dilution effect of the fibre, reducing nutrient absorption and consequently stimulating villus growth to improve absorption rates.     

Cryopreservation of immature oocytes of the indigeneous Vietnamese Ban Pig

We report the cryopreservation of oocytes from Ban miniature pigs which are endemic in Vietnam. Immature cumulus‐oocyte complexes were collected from antral follicles of 7–8 mo old female cyclic Ban pigs and vitrified in micro‐drops. Oocyte morphology, lipid content, post‐warming survival, nuclear maturation, and embryo development were compared to those of oocytes from commercially slaughtered Landrace × Large white hybrid pigs. The size of oocytes in the two breeds was similar. However, significantly lower amounts of intracellular lipid were detected in Ban oocytes. There was no difference (p > 0.05) between Ban and Landrace × Large white oocytes in percentages of post‐warming survival (93.1 ± 3.4% vs. 70.7 ± 16.7%, respectively) and nuclear maturation after in vitro maturation (80.4 ± 5.1% vs. 90.0 ± 1.3% respectively). Similarly, cleavage (30.8 ± 7.8% vs. 10.3 ± 6.1%, respectively) and blastocyst development rates (9.4 ± 5.0% vs. 0.79 ± 0.79, respectively) were not different (p > 0.05) between vitrified Ban and Landrace × Large white oocytes after in vitro fertilization and embryo culture. In conclusion, high survival and maturation rates were achieved after vitrification of immature Ban oocytes and their cryo‐tolerance was similar to that of Landrace × Large white oocytes, despite the difference in lipid content. We succeeded to generate reasonable rates of blastocysts from vitrified Ban oocytes by in vitro fertilization.