草鱼乙酰辅酶A羧化酶β基因全长cDNA分子克隆与表达分析

本试验采用反转录PCR(RT-PCR)和c DNA末端快速扩增(RACE)技术克隆获得草鱼乙酰辅酶A羧化酶β(ACC2)基因全长c DNA,并采用实时荧光定量PCR技术研究ACC2基因在肝胰脏、脾脏、大脑、前肠、中肠、后肠、肾脏、肌肉、心脏和肠系膜脂肪等组织中的表达,同时,还对饲喂不同脂肪源饲料12周后草鱼肝胰脏和肌肉中以及饥饿再次投喂后3、6、12和24 h肝胰脏中ACC2 mRNA的表达变化进行了研究。结果显示:草鱼ACC2基因c DNA全长7 533 bp,含1个7 149 bp的开放阅读框,编码2 382个氨基酸,ACC2蛋白计算分子质量为268.34 ku,等电点为6.13。草鱼ACC2基因存在可变剪接,形成另外1个同工型(isoforms),比分子质量为268.34 ku的ACC2蛋白少8个氨基酸。ACC2基因在所有检测组织中均有表达,ACC2 mRNA的相对表达量在肌肉中最高,为29.13,在肝胰脏中最低,仅为1.90。肌肉中ACC2 mRNA的相对表达量与大脑、前肠和心脏差异不显著(P0.05),但显著高于其他组织(P0.05)。投喂不同脂肪源饲料对草鱼肝胰脏及肌肉中ACC2 mRNA相对表达量无显著影响(P0.05);饥饿再投喂后草鱼肝胰脏中ACC2 mRNA相对表达量在12 h达到高峰值,为6.17,之后明显下降,24 h时仅为2.84。本试验成功克隆了草鱼ACC2基因全长c DNA,其主要的功能位点ATP结合位点、生物素结合位点与其他脊椎动物相比基本保守。草鱼ACC2基因主要在肌肉等脂肪分解活跃的组织中表达,投喂不同脂肪源饲料对草鱼肝胰脏中ACC2 mRNA的相对表达量无显著影响;饥饿再投喂后,肝胰脏中ACC2 mRNA的相对表达量在投喂12 h后最高。     

投喂高脂饲料后草鱼主要生化指标和乙酰辅酶A羧化酶1 mRNA表达的变化

为了研究草鱼肝脏对高脂饲料的代谢调控机理,试验研究了连续12周投喂含8.1%脂肪的饲料对草鱼血清生化指标、肝胰脏生化指标及乙酰辅酶A羧化酶1(ACC1)mRNA表达的影响。将120尾平均体重为(15.0±2.4)g的健康草鱼随机为高脂组和基础组,分别投喂含8.1%脂肪的高脂饲料和4.6%脂肪的基础饲料,并在试验的第4、8、12周检测草鱼血清中甘油三酯(TG)、总胆固醇(CHO)含量及谷丙转氨酶(ALT)、谷草转氨酶(AST)活性以及肝胰脏中丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性。在试验第12周,制作病理切片观察肝胰脏组织形态,并应用半定量反转录聚合酶链式反应(RT-PCR)检测肝胰脏ACC1 mRNA的相对表达量。结果表明:试验期间,高脂组草鱼肝细胞出现损伤,并随投喂时间的延长而加重;高脂组草鱼血清中AST、ALT活性及TG、CHO含量以及肝胰脏中MDA含量均随投喂时间的延长而显著或极显著上升(P<0.05或P<0.01),而肝胰脏中SOD和CAT活性则随投喂时间的延长而显著或极显著下降(P<0.05或P<0.01)。在试验第12周,高脂组草鱼血清中AST、ALT活性及TG、CHO含量以及肝胰脏中MDA含量均显著或极显著高于基础组(P<0.05或P<0.01),而肝胰脏中SOD和CAT活性则显著或极显著低于基础组(P<0.05或P<0.01);与基础组相比,高脂组草鱼肝胰脏ACC1 mRNA相对表达量极显著升高(P<0.01)。由此得出,高脂饲料的连续投喂升高了草鱼的血脂水平,并使草鱼肝胰脏出现损伤,其作用机制可能与高脂饲料降低草鱼抗氧化能力以及促进肝脏脂肪合成有关。     

鹅ACSL4基因克隆及其与肝脂质沉积的关系研究

本研究旨在克隆鹅长链酯酰辅酶A合成酶4(ACSL4)基因,探讨其与鹅肝脂质沉积的关系和品种间的表达差异。本实验通过RT-PCR、实时定量等技术扩增鹅ACSL4基因CDS、检测了该基因在皮脂、腹脂、肝脏等10个组织中的表达情况及填饲对其在肝脏中表达的影响,并探讨其表达量与血浆胰岛素、鹅肝脏甘油三酯(TG)、肝重等指标间的相关性。结果表明:鹅ACSL4基因CDS全长2 013 bp,编码670个氨基酸。保守结构预测发现,其蛋白质与哺乳动物一样,也存在2个保守功能区(ATP/AMP motif和FACS motif),它与鸡、人、猪、小鼠、大鼠的同源性分别为96.9%、80.4%、80.1%、78.5%、78.4%;组织表达结果显示,该基因主要于大脑、腹脂、心肌、睾丸等组织中表达,而在肝脏中表达相对较低;填饲引起ACSL4 mRNA在鹅肝脏的表达丰度极显著增加(P<0.01);且与肝脏脂质沉积相关指标呈显著正相关(P<0.05),暗示其在鹅肝脂肪变性中可能扮演着重要的角色。     

饲料中维生素D3水平对黄鳝抗菌肽hepcidin基因表达的影响

本试验旨在探索饲料中维生素D3水平对黄鳝(Monopterus albus)抗菌肽hepcidin基因表达的影响.挑选体质健康、平均体重为(21.7±2.1)g的黄鳝360尾,随机分为6组,每组2个重复,每个重复30尾.6组黄鳝分别饲喂在基础饲料(0 IU/kg维生素D3)中添加0、250、500、1 000、2 000和4 000 IU/kg维生素D3的试验饲料.于投喂试验饲料后20、40和60 d,从各组随机选择6尾黄鳝,分别采集其肝胰脏、脾脏、头肾和后肠组织,采用荧光定量聚合酶链式反应(RT-PCR)技术检测样品中hepcidin基因表达量.结果表明:投喂20、40和60 d后,黄鳝4种组织中均有hepcidin基因表达,并且肝胰脏中显著高于脾脏、头肾和后肠中(P＜0.05);随维生素D3添加水平的增加,黄鳝hepcidin基因在4种组织的表达量同一时间点均呈现出先升高后降低的趋势;第20天时4种组织中的表达量均以2 000 IU/kg组为最高,显著高于其他各组(P＜0.05);第40和60天时肝胰脏、头肾中的表达量均以500 IU/kg组为最高,其中第40天时显著高于0、250、4 000 IU/kg组(P＜0.05),第60天时显著高于其他各组(P＜0.05).结果提示,短期(20 d)内在饲料中添加2 000 IU/kg的维生素D3可显著提高黄鳝内脏组织中hepcidin 基因的表达量;饲喂周期较长(40或60 d)时,饲料中添加500 IU/kg维生素D3可显著提高hepcidin基因在黄鳝肝胰脏和头肾中的表达量.     

草原红牛ACSL3基因CDS区克隆、生物信息学分析及组织表达研究

试验旨在克隆草原红牛长链酰基辅酶A合成酶3(long-chain acyl-CoA synthetase 3,ACSL3)基因编码区并对其进行生物信息学分析,同时在mRNA和蛋白质水平上分析ACSL3基因在草原红牛不同组织中的表达差异。利用RT-PCR技术和TA克隆的方法获得草原红牛ACSL3基因CDS序列;利用在线软件对ACSL3基因进行生物信息学分析,分析ACSL3基因与其他物种的同源性并构建系统进化树,分析ACSL3基因编码蛋白质的基本理化性质、潜在磷酸化位点、O-糖基化位点、N-糖基化位点、信号肽、二硫键、跨膜区结构、亚细胞定位及该基因编码蛋白的二级结构、三级结构;通过实时荧光定量PCR和Western blotting技术检测ACSL3基因在草原红牛各组织间的mRNA和蛋白表达水平。结果显示,试验成功克隆了草原红牛ACSL3基因CDS区,全长2 163 bp,编码720个氨基酸,蛋白分子质量为80.28 ku,理论等电点为8.74,属于亲水性蛋白。通过NCBI中BLAST比对发现,草原红牛与牛、绵羊、猪、人、大鼠、小鼠、鸡的ACSL3基因核苷酸序列同源性分别为99%、97%、93%、91%、88%、88%和78%;系统进化树结果表明,草原红牛与牛、绵羊的亲缘关系最近,与鸡的亲缘关系最远。该蛋白序列有7个二硫键,66个磷酸化位点,9个O-糖基化位点,3个N-糖基化位点,不存在信号肽,但存在1个跨膜区。二级结构和三级结构分析结果表明,ACSL3蛋白通过无规则卷曲连接,蛋白质结构以α-螺旋和β-转角为主,为混合型蛋白。mRNA和蛋白表达量检测结果显示,ACSL3基因在肾脏和肌肉组织中表达量较高,显著高于其他组织(P<0.05);在胃、肝脏和心脏中中度表达,显著高于脾脏、肺脏、肠和脂肪(P<0.05);在脾脏、肺脏、肠和脂肪中相对低表达,说明草原红牛ACSL3基因可能与体内脂肪沉积和脂质代谢等调控功能有关。本试验结果为进一步研究ACSL3基因在草原红牛中脂质代谢及脂肪沉积等方面的调控作用提供了基础材料。     

丙二醛引起草鱼肠道、肝胰脏谷胱甘肽/谷胱甘肽转移酶通路抗氧化应激

为了研究丙二醛(MDA)对草鱼肠道、肝胰脏抗氧化防御能力的影响,以谷胱甘肽(GSH)/谷胱甘肽转移酶(GSTs)通路为研究对象,选择初始体重(74.8±1.0)g的草鱼(Ctenopharyngodon idelluspond),随机分为4组,每组设3个重复,每个重复20尾。4组草鱼分别投喂基础饲料(对照组)以及在基础饲料中添加61(B1组)、124(B2组)、185 mg/kg(B3组)MDA的试验饲料,在池塘网箱养殖72 d后,测定肠道、肝胰脏和血清中MDA和GSH含量,采用荧光定量PCR(qRT-PCR)方法测定草鱼肠道、肝胰脏GSH/GSTs通路中谷氨酸-半胱氨酸连接酶催化亚基(GCLC)、谷胱甘肽还原酶(GSR)、pi-谷胱甘肽硫转移酶(GSTpi)、微粒体谷胱甘肽硫转移酶1(MGSt1)基因表达量。结果显示:1)与对照组相比,除B3组肝胰脏MDA含量显著升高(P0.05)外,其余试验组肠道、肝胰脏MDA含量均无显著变化(P0.05);各试验组血清MDA含量均显著升高(P0.05)。2)与对照组相比,除B1、B3组肠道GSH含量显著升高(P0.05)外,其余试验组肠道、肝胰脏GSH含量均无显著变化(P0.05);B1、B2组血清GSH含量显著升高(P0.05)。3)与对照组相比,B2、B3组肠道及B1组肝胰脏GCLC表达量显著上调(P0.05);除B2组肠道G SR表达量显著上调(P0.05)外,其余试验组肠道和肝胰脏G SR表达量均无显著变化(P0.05);B2、B3组肠道及B3组肝胰脏GSTpi表达量显著上调(P0.05);B3组肠道MGST1表达量显著上调(P0.05);各试验组肝胰脏MGST1表达量均显著下调(P0.05)。结果表明,MDA引起草鱼肠道、肝胰脏GSH/GSTs通路抗氧化应激反应,且肠道和肝胰脏受M DA的影响程度有一定的差异。     

草原红牛ACSL3基因CDS区克隆、生物信息学分析及组织表达研究

试验旨在克隆草原红牛长链酰基辅酶A合成酶3(long-chain acyl-CoA synthetase 3,ACSL3)基因编码区并对其进行生物信息学分析,同时在mRNA和蛋白质水平上分析ACSL3基因在草原红牛不同组织中的表达差异。利用RT-PCR技术和TA克隆的方法获得草原红牛ACSL3基因CDS序列;利用在线软件对ACSL3基因进行生物信息学分析,分析ACSL3基因与其他物种的同源性并构建系统进化树,分析ACSL3基因编码蛋白质的基本理化性质、潜在磷酸化位点、O-糖基化位点、N-糖基化位点、信号肽、二硫键、跨膜区结构、亚细胞定位及该基因编码蛋白的二级结构、三级结构;通过实时荧光定量PCR和Western blotting技术检测ACSL3基因在草原红牛各组织间的mRNA和蛋白表达水平。结果显示,试验成功克隆了草原红牛ACSL3基因CDS区,全长2 163 bp,编码720个氨基酸,蛋白分子质量为80.28 ku,理论等电点为8.74,属于亲水性蛋白。通过NCBI中BLAST比对发现,草原红牛与牛、绵羊、猪、人、大鼠、小鼠、鸡的ACSL3基因核苷酸序列同源性分别为99%、97%、93%、91%、88%、88%和78%;系统进化树结果表明,草原红牛与牛、绵羊的亲缘关系最近,与鸡的亲缘关系最远。该蛋白序列有7个二硫键,66个磷酸化位点,9个O-糖基化位点,3个N-糖基化位点,不存在信号肽,但存在1个跨膜区。二级结构和三级结构分析结果表明,ACSL3蛋白通过无规则卷曲连接,蛋白质结构以α-螺旋和β-转角为主,为混合型蛋白。mRNA和蛋白表达量检测结果显示,ACSL3基因在肾脏和肌肉组织中表达量较高,显著高于其他组织(P0.05);在胃、肝脏和心脏中中度表达,显著高于脾脏、肺脏、肠和脂肪(P0.05);在脾脏、肺脏、肠和脂肪中相对低表达,说明草原红牛ACSL3基因可能与体内脂肪沉积和脂质代谢等调控功能有关。本试验结果为进一步研究ACSL3基因在草原红牛中脂质代谢及脂肪沉积等方面的调控作用提供了基础材料。     

玉屏风多糖对草鱼肠黏膜形态结构及主要免疫与吸收相关基因表达的影响

本试验旨在探讨不同比例玉屏风多糖对草鱼肠黏膜形态结构及主要免疫与吸收相关基因表达的影响。试验选择750尾平均体重为(74.50±2.50)g的健康草鱼,随机分为5组,每组6个重复,每个重复25尾。对照组(Ⅰ组)投喂基础饲料,试验组(Ⅱ~Ⅴ组)投喂在基础饲料基础上分别添加0.8、1.2、1.6、2.0 g/kg玉屏风多糖的试验饲料。预试期7 d,正试期28 d。结果表明:1)与对照组相比,在试验第14天时,Ⅴ组的隐窝深度显著降低(P0.05),而绒腺比则显著提高(P0.05)。2)对照组相比,在试验第7天时,Ⅲ和Ⅳ组头肾中白介素-2(IL-2)mRNA相对表达量显著或极显著提高(P0.05或P0.01),Ⅱ、Ⅲ、Ⅳ和Ⅴ组头肾中干扰素γ(IFN-γ)mRNA相对表达量均极显著提高(P0.01),Ⅲ、Ⅳ和Ⅴ组肠道中钠葡萄糖转运蛋白1(SG LT-1)和葡萄糖转运蛋白2(GLUT-2)mRNA相对表达量显著或极显著提高(P0.05或P0.01))。3)与对照组相比,在试验第14天时,Ⅳ和Ⅴ组头肾中IL-2 mRNA相对表达量极显著提高(P0.01),Ⅱ、Ⅲ、Ⅳ和Ⅴ组头肾中IFN-γmRNA相对表达量显著或极显著提高(P0.05或P0.01),Ⅲ、Ⅳ和Ⅴ组肠道中SG LT-1和G LUT-2 mRNA相对表达量极显著提高(P0.01)。4)与对照组相比,在试验第21天时,Ⅳ组头肾中IL-2 mRNA相对表达量显著提高(P0.05),Ⅱ、Ⅲ、Ⅳ和Ⅴ组头肾中IFN-γmRNA相对表达量极显著提高(P0.01),Ⅱ、Ⅲ、Ⅳ和Ⅴ组肠道中SG LT-1和G LUT-2 mRNA相对表达量显著或极显著提高(P0.05或P0.01)。5)与对照组相比,在试验第28天时,Ⅳ和Ⅴ组头肾中IL-2 mRNA相对表达量极显著提高(P0.01),Ⅲ、Ⅳ和Ⅴ组头肾中IFN-γmRNA相对表达量显著或极显著提高(P0.05或P0.01),Ⅱ、Ⅲ、Ⅳ和Ⅴ组肠道中SGLT-1 mRNA相对表达量显著或极显著提高(P0.05或P0.01)。综上所述,在草鱼饲料中添加一定量的玉屏风多糖能够改善肠黏膜形态结构,促进肠道中SGLT-1和GLUT-2基因的表达,调控头肾中IL-2和IFN-γ基因的表达,从而提高肠道吸收功能、增强机体免疫力。从节约饲养成本出发,草鱼饲料中玉屏风多糖最适添加量为1.6 g/kg。     

鹅ACSL1基因克隆及其在鹅肥肝形成中作用的初步研究

本研究旨在克隆鹅长链酯酰辅酶A合成酶1(ACSL1)基因,并研究其在填饲诱导鹅肥肝形成中的作用,为揭示ACSL1在鹅肥肝形成过程中的作用提供依据。以前期抑制消减杂交文库筛选的部分ESTs序列为基础,通过RT-PCR扩增鹅ACSL1基因CDS、并用实时定量等技术检测该基因在皮脂、腹脂、肝脏等10个组织中的表达情况及填饲对其在肝脏中表达的影响,同时与填饲后鹅肝脏总脂质、甘油三酯(TG)、肝质量等指标进行相关分析。结果发现:鹅ACSL1基因CDS全长2100bp,编码699个氨基酸。保守结构区预测发现,其蛋白质跟其他物种一样,也存在2个保守功能区(ATP/AMPmotif和FACSmotif)和1个跨膜结构域,它与鸡、牛、人、小鼠ACSL1基因的同源性分别为93%、80.4%、78.5%、77.3%;该基因主要表达于腹脂、皮脂、肝脏,而在其他组织表达相对较低;填饲能引起ACSL1mRNA在鹅肝脏的表达丰度极显著增加(P0.01),且与肝质量、肝内TG和总脂质呈显著正相关;同时,填饲导致其在朗德鹅肝脏中的表达丰度显著高于四川白鹅(P0.05)。结果提示:填饲引起ACSL1mR-NA在鹅肝脏中极显著增加(P0.01),且其增加幅度存在着品种间差异(P0.05)。     

饲料中糊精水平对乌克兰鳞鲤生长及糖代谢的影响

为了探讨饲料中糊精水平对乌克兰鳞鲤生长和糖代谢的影响,试验配制蛋白质水平为30%,糊精水平分别为15%和25%的2种试验饲料,以平均体重为3.92 g的乌克兰鳞鲤幼鱼为试验对象,将300尾鱼随机分为2组,每组设3个重复,每个重复50尾鱼。饲养8周后,检测乌克兰鳞鲤生长指标、生化指标和糖代谢酶活性;禁食48 h后再投喂,测定投喂后0、3、6、12、24、48 h肝胰脏和肠道葡萄糖激酶(GK)和葡萄-6-磷酸酶(G6 Pase)mRNA的表达量。结果表明:1)25%糊精组的特定生长率显著高于15%糊精组(P0.05)。2)25%糊精组的血清甘油三酯、胆固醇和葡萄糖含量显著高于15%糊精组(P0.05)。3)25%糊精组血清己糖激酶(HK)、GK、丙酮酸激酶(PK)、苹果酸脱氢酶(MDH)活性,肝胰脏HK、GK、G6 Pase活性显著高于15%糊精组(P0.05),而肝胰脏MDH活性则显著低于15%糊精组(P0.05)。4)再投喂24 h后25%糊精组肝胰脏GK mRNA的表达量显著高于15%糊精组(P0.05)。再投喂6 h后,25%糊精组G6Pase mRNA表达量显著高于15%糊精组(P0.05)。综合分析,在本试验条件下,25%的饲料糊精水平对乌克兰鳞鲤生长和糖代谢的促进作用好于15%的饲料糊精水平。     

Effects of Bacillus subtilis C‐3102 on production,hatching performance,egg quality,serum antioxidant capacity and immune response of laying breeders

To investigate the supplemental effects of Bacillus subtilis C‐3102 on the production, hatching performance, egg quality, serum antioxidant capacity and immune response of laying breeders, a total of 480 Xuefeng black‐bone (25‐week‐old) hens were randomly assigned into four treatment groups: Hens fed the basal diets with 0 (CON), 3.0 × 10⁵ (BS‐1), 6.0 × 10⁵ cfu/g (BS‐2) and 9.0 × 10⁵ (BS‐3) cfu/g of B. subtilis C‐3102. As the B. subtilis C‐3102 level increased, egg weight (linear, p < 0.01; quadratic, p = 0.003), fertility (linear, p = 0.021; quadratic, p = 0.059), hatchability (linear, p = 0.038; quadratic, p = 0.119) and yolk colour (linear, p = 0.006; quadratic, p = 0.021) increased in a linear or quadratic manner. Yolk index increased quadratically (linear, p = 0.054; quadratic, p = 0.017), and eggshell thickness (linear, p = 0.036; quadratic, p = 0.128), the activity of GSH‐Px (linear, p = 0.024; quadratic, p = 0.078), the concentration of IgM (linear, p = 0.016; quadratic, p = 0.056) and the level of AIV‐Ab (linear, p = 0.034; quadratic, p = 0.103) in the serum increased linearly as dietary supplementation of B. subtilis C‐3102 increased. The results showed that dietary treatments did not affect egg production, feed conversion ratio, egg mass, hatchability of fertile eggs, eggshell‐breaking strength, egg‐shape index, yolk percentage, Haugh unit, T‐SOD, T‐AOC, MDA, IgA and IgG concentrations and the level of NDV‐Ab in the serum. In conclusion, dietary supplementation of 9.0 × 10⁵ cfu/g B. subtilis C‐3102 in laying breeders diets may be a feasible means of effectively increasing egg weight, fertility and hatchability, and improving egg quality such as eggshell thickness, yolk index and yolk colour. Besides, B. subtilis C‐3102 can enhance the activity of GSH‐Px, the concentration of IgM and the level of AIV‐Ab in the serum.     

Low‐density lipoproteins and milk serum proteins improve the quality of stallion sperm after vitrification in straws

Lipids and proteins can be used for sperm vitrification to preserve the integrity of sperm membranes or to increase the viscosity of the medium. This study evaluated the effect of low‐density lipoproteins (LDL) and milk serum proteins (Pronexcell) for stallion sperm vitrification. Hippex extender (Barex Biochemical Products, The Netherlands), plus 1% of bovine serum albumin and 100 mM of trehalose, was used as control for sperm vitrification. In experiment 1, different concentrations of LDL (L1 = 0.25, L2 = 0.5, L3 = 1%) and in experiment 2 of Pronexcell (P1 = 1, P2 = 5, P3 = 10%) were added to control extender. Vitrification was performed in 0.25‐ml straws directly plunged into liquid nitrogen. Total motility (TM, %) and progressive motility (PM, %) were analysed by CASA, and plasma membrane (IMS, %) and acrosome membrane integrity (AIS, %) were assessed under epifluorescence microscopy. Post‐warmed sperm parameters were compared between treatments by ANOVA. Results were expressed as mean ± SEM. In both experiments, the minimum concentration of LDL and Pronexcell obtained significantly higher values (p < 0.01) than the control extender for TM (L1 = 52.95 ± 4.4; P1 = 58.99 ± 4.6; C = 30.88 ± 3.0), PM (L1 = 36.79 ± 5.5; P1 = 47.25 ± 4.3; C = 19.20 ± 2.4), IMS (L1 = 68.88 ± 3.6; P1 = 47.25 ± 4.3; C = 52.81 ± 2.6) and AIS (L1 = 45.88 ± 3.6; P1 = 47.25 ± 4.3; C = 26.00 ± 2.1). No differences in sperm parameters were found among different concentrations of LDL or Pronexcell. In conclusion, the addition of 0.25% LDL and 1% Pronexcell to the vitrification extender is recommended to improve the quality of stallion sperm after vitrification.     

A meta-analysis on effects of supplementing low-quality roughages with foliages from browses and tree fodders on intake and growth in sheep

A meta-analysis of data obtained from previous studies was conducted to understand the responses of foliage supplementation on intakes of basal DM (BDMI) and total DM (TDMI), and daily gain (ADG). Thirty-four published studies containing 223 treatments and 1127 sheep met criteria for inclusion in the meta-analysis. Major predictive variables considered were percentages of foliages in diet (SD), CP in foliages (PS), NDF in foliages (FS), NDF in forages (FB), CP in basal roughages (PB), CP in diet (PD) and foliage CP intake (SPI). TDMI (g/d) increased quadratically (P < 0.001) with increasing PS, FS, SPI (R² = 0.66), PB, SD (R² = 0.58) and PD (R² = 0.73). The maximal response of TDMI were 778 g/d at 42% of SD, 894 g/d at 19.8% PD, 893 g/d at 148 g/d SPI and 749 g/d at 26.4% PS (P < 0.001; R² = 0.58, 0.73, 0.66, and 0.37, respectively). BDMI increased quadratically with increasing SD, PD and PB, but decreased quadratically (P < 0.001) with increasing PS (P < 0.001; R² = 0.07). The breakpoint of BDMI was 570 g/d at 6.58% of PD in the diet (P < 0.001, R² = 0.28). Overall, BDMI responded at very low level of SD in the diet, peaking at 7.6% SD with BDMI of 572 g/d (P < 0.001, R² = 0.72). However, when PB was less than 3%, the maximal BDMI was 489 g/d at foliage levels of 25.7%. When PB was between 3 and 6%, maximal BDMI was at 13% of foliage in the diet and the basal forage intake of 597 g/d; whereas, BDMI decreased linearly with SD when PB was greater than 6%. BDMI (g/d) decreased quadratically when foliage CP percentages were lesser than 10%, but increased quadratically with PS when foliage CP percentages were greater than 10%. ADG responded positively and quadratically to PS, SPI, SD, PD and TDMI (g/d) and the relationships were moderate to high. However, ADG (g/d) decreased linearly with increasing FS (P < 0.001, R² = 0.35). The maximal ADG was 42 g/d at 43% of SD, 41 g/d at 9.4% PD, 42 g/d at 53 g/d SPI, 35 g/d at 25% PS and 46 g/d at TDMI of 889 g/d (P < 0.001; R² = 0.74, 0.84, 0.74, 0.29 and 0.74, respectively). It is concluded that the interactions of quality and quantity of foliage supplements and quality of basal forages affect intakes of basal and total DM, and growth in sheep.     

Comparison of the sedative effects of intranasal or intramuscular dexmedetomidine at low doses in healthy dogs: a randomized clinical trial

ObjectiveTo compare the sedative effects of dexmedetomidine administered either intranasally or intramuscularly to healthy dogs.Study designProspective, randomized, blinded, clinical trial.AnimalsA group of 16 client-owned healthy dogs.MethodsDogs were randomly allocated to one of two groups that were administered dexmedetomidine 5 μg kg^–1 via either the intranasal route (IN_Dex), through a mucosal atomization device in one nostril, or the intramuscular route (IM_Dex), into the epaxial muscles. Ease of intranasal administration, sedation score, onset of sedation, cardiopulmonary variables, mechanical nociceptive thresholds (MNTs) and response to venous catheterization were recorded at 0 (baseline), 5, 10, 15, 20, 25, 30, 35, 40 and 45 minutes, following drug administration. Data were compared with the one-way anova, Mann-Whitney U test, and chi-square test, where appropriate.ResultsGroups were not different for age, sex, weight, body condition score or temperament. Sedation scores, MNTs and response to intravenous catheter placement were not different when dexmedetomidine was administered by either route (p = 0.691; p = 0.630 and p = 0.435, respectively). Onset of sedation was not different between groups IN_Dex and IM_Dex reaching a score of 4.2 ± 0.9 and 5.5 ± 1.2 at 9 ± 5 and 8 ± 4 minutes, respectively (p = 0.467). The highest sedation score was achieved at 30 and 35 minutes and sedation scores were 9.7 ± 2.0 and 9.5 ± 2.3 in groups IN_Dex and IM_Dex, respectively (p = 0.799). Respiratory rate was higher in group IN_Dex (p = 0.014), while there were no differences between routes in heart rate (p = 0.275), systolic (p = 0.957), diastolic (p = 0.837) or mean arterial pressure (p = 0.921).Conclusions and clinical relevanceIntranasal administration of dexmedetomidine at 5 μg kg^–1 provides effective sedation in healthy dogs.     

Comparison on the physico‐chemical and nutritional qualities of normal and abnormal colored fresh chicken liver

This study evaluated the differences of physico‐chemical and nutritional qualities between abnormal colored chicken livers (ANCCLs) and normal colored chicken livers (NCCLs) and the safety of the both livers. Compared with NCCLs, ANCCLs were lower in protein, water contents (P < 0.01), pH and pigment contents (P < 0.05). NCCLs contained higher polyunsaturated fatty acid (PUFA) and saturated fatty acids (SFA) (P < 0.05). The PUFA/SFA ratio of NCCLs was 0.453, higher (P < 0.05) than that of ANCCLs. The contents of alanine, valine, tyrosine, lysine and histidine in NCCLs were higher (P < 0.05) than in ANCCLs. The contents of K, Na, P, Cu, Fe and Se of NCCLs were higher (P < 0.05), but the Ca content was lower (P < 0.05). The content of the heavy metals (As, Hg, Pb and Cd) of the two types of livers complied with food safety requirements. Although NCCLs had higher nutritional value than ANCCLs, both livers were acceptable for human consumption.     

Methane emissions and δ13C composition from beef steers consuming increasing proportions of sericea lespedeza hay on bermudagrass hay diets

An experiment was conducted to evaluate the effects of different proportions of ‘Au Grazer’ sericea lespedeza [SL, Lespedeza cuneata (Dum. Cours.) G. Don], a legume rich in condensed tannins (CT), on nutrient intake and digestibility, and to estimate methane (CH₄) emissions and ¹³C isotopic composition (δ¹³C_CH4) from beef steers consuming a forage-based diet. Twenty-five Angus-crossbred steers were distributed in a randomized complete block design (344 ± 48 kg initial BW), and randomly assigned to one of five treatments: 0SL, 25SL, 50SL, 75SL, and 100SL, diets containing 0%, 25%, 50%, 75%, and 100% of SL hay, respectively, mixed with ‘Tifton-85’ bermudagrass hay (Cynodon spp.). The study was carried out for two experimental periods of 21-d each. The statistical model included the fixed effect of treatment and random effects of block, experimental period, and their interaction. Apparent total tract digestibility of crude protein, neutral detergent fiber, and acid detergent fiber was linearly decreased (P < 0.001) by the inclusion of SL. No effects were observed for total CH₄ emissions per day, nor for CH₄ relative to organic matter intake or digestible organic matter with the inclusion of SL. However, emission of CH₄ in relation to intake of CT was affected by treatment (P < 0.001). A linear (P < 0.001) decrease and a quadratic effect (P < 0.001) were observed for δ¹³C of diets and gas, respectively, in which diets and enteric CH₄ with greater inclusion of SL were more depleted in ¹³C. Moreover, the difference in δ¹³C between diets and gas (Δδ¹³C) had a linear decrease (P = 0.001) with the inclusion of SL. The model developed to predict the C₃ proportions in the enteric CH₄ fitted to predicted values (P < 0.0001). Therefore, greater proportions of SL resulted in lesser CH₄ emission when CT intake was considered and the isotopic composition from enteric CH₄ was able to predict the contribution of SL in the emissions.     

Effect of food on the pharmacokinetics of oral cefuroxime axetil in dogs

Cefuroxime axetil pharmacokinetic profile was investigated in 12 Beagle dogs after single intravenous and oral administration of tablets or suspension at a dose of 20 mg/kg, under both fasting and fed conditions. A three-period, three-treatment crossover study (IV, PO under fasting and fed condition) was applied. Blood samples were withdrawn at predetermined times over a 12-hr period. Cefuroxime plasma concentrations were determined by HPLC. Data were analyzed by compartmental analysis. No statistically significant differences were observed between formulations and feeding conditions on PK parameters. Independently of the feeding condition, absorption of cefuroxime axetil after tablet administration was low and erratic. The drug has been quantified in plasma in 3 out of 6 and 5 out of 6 dogs in the fasted and fed groups. For this formulation, the bioavailability (F), peak plasma concentration (C_max), and area under the concentration–time curve (AUC) of cefuroxime axetil were significantly enhanced (p < .05) by the concomitant ingestion of food (32.97 ± 13.47–14.08 ± 7.79%, 6.30 ± 2.62–2.74 ± 0.66 µg/ml, and 15.75 ± 3.98–7.82 ± 2.76 µg.hr/ml for F, C_max, and AUC in fed and fasted dogs, respectively), while for cefuroxime axetil suspension, feeding conditions affected only the rate of absorption, as reflected by the significantly shorter absorption half-life (T_½(a)) and time to peak concentration (T_max) (0.55 ± 0.27–1.15 ± 0.19 hr and 1.21 ± 0.22–1.70 ± 0.30 for T_½(a) and T_max in fed and fasted dogs, respectively). For cefuroxime axetil tablets, T > MIC (≤1 µg/ml) was <2 hr in fasted and ≈4 hr in fed animals, and for cefuroxime axetil suspension, T > MIC (≤1 µg/ml) was ≈5 hr and for T >MIC (≤4 µg/ml) was ≈2.5 hr for fasted and fed dogs, respectively. Cefuroxime axetil as a suspension formulation seems to be a better option than tablets. However, its short permanence in plasma could reduce its clinical usefulness in dogs.     

Luteal vascularity and embryo dynamics in mares during early gestation: Effect of age and endometrial degeneration

The present study characterized the luteal status and the dynamic of the conceptus during the first 20 days of gestation in mares with different ages and degrees of endometrial degeneration. Total area of the corpus luteum (CL), luteal vascularity, CL area with blood signals, progesterone concentrations (P4), embryonic vesicle diameter, number of embryonic location changes, embryonic fixation position and uterine contractility were evaluated. In Experiment 1, mares ≤6 years of age (Young group, 5.6 ± 0.2 years, n = 7 mares) and mares ≥15 years of age (Old group, 17.2 ± 0.9 years, n = 6 mares) were used to investigate the effect of age. In Experiment 2, the luteal and embryonic parameters were compared between mares with minimal (Mild group, endometrial category I, n = 9 mares) and severe (Severe group, endometrial category III, n = 7 mares) endometrial degeneration. The Old and Severe groups had greater (p ≤ 0.04) total CL area and reduced luteal vascularity (p ≤ 0.04) than the Young and Mild groups, respectively. However, P4 levels and CL area with blood signals were similar (p ≥ 0.8) between the groups. A negative effect of age (p < 0.01), but not of endometrial degeneration (p = 0.6), was found for the embryonic vesicle diameter. The conceptus mobility was high (p > 0.1) until day 14 of gestation in the Severe group, while a reduced number of changes of the embryo location was detected earlier (p < 0.05) in the Old group. In conclusion, the newly formed CL of aged mares and mares with severe endometrial degeneration suffered a structural remodelling to safeguard the local blood supply and the continuous P4 output during early gestation. Moreover, an earlier reduction of the embryonic mobility and a delayed development of the conceptus were associated with advanced age, regardless of the degree of endometrial degeneration.     

Net requirements of calcium, magnesium, sodium, phosphorus, and potassium for growth of Nellore × Red Angus bulls, steers, and heifers

A comparative slaughter trial was conducted to assess the net requirements for gain of Ca, P, Na, K and Mg of bulls, steers and heifers of Nellore and Red Angus crossbreds. Twenty seven F1 Nellore and Red Angus crossbred calves (9 steers, 9 bulls, and 9 heifers), averaging 274 kg BW, were used. At the beginning of the trial, three animals from each gender were slaughtered to determine the initial body composition. The remaining 18 animals (3 animals of each gender) were randomly assigned to two treatments: fed 0.75 or 1.5% of BW of concentrate. The diets were based on corn silage and were isonitrogenous (2% N, DM). After three growing periods of 28 d, all animals were slaughtered. The cleaned gastrointestinal tract, organs, carcass, head, hide, tail, feet, and tissues were weighed to determine the empty BW (EBW). These parts were ground separately and subsampled for chemical analyses. The log of the contents of each mineral in the empty body was regressed on the log of the EBW to estimate the net requirement for each mineral per kg of empty body gain (EBG). There were no differences (P > 0.05) in the net requirements for growth of all macrominerals among genders. The equations of the pooled data of the net requirements for growth (g/kg EBG) were: 332.6 × EBW ^− 0.6367 for Ca, 112.1 × EBW ^− 0.5615 for P, 10.85 × EBW ^− 0.3992 for Na, 4.01 × EBW ^− 0.153 for K, and 3.589 × EBW ^− 0.462 for Mg. Our findings indicated that retained Ca and retained P were poorly related to the retained protein.     

Tilmicosin enteric granules and premix to pigs: Antimicrobial susceptibility testing and comparative pharmacokinetics

The purpose of this study was to compare the pharmacokinetics and relative bioavailability of tilmicosin enteric granules and premix after oral administration at a dose of 40 mg/kg in pigs. Three kinds of different respiratory pathogens were selected for determination of minimal inhibitory concentration (MIC) to tilmicosin. Eight healthy pigs were assigned to a two‐period, randomized crossover design. A modified rapid, sensitive HPLC method was used for determining the concentrations of tilmicosin in plasma. Pharmacokinetic parameters were calculated by using WinNonlin 5.2 software. The MIC₉₀ of tilmicosin against Haemophilus parasuis, Actinbacillus pleuropneumoniae, and Pasteurella multocida were all 8 μg/ml. These results indicated that these common pig respiratory bacteria are sensitive to tilmicosin. The main parameters of time to reach maximum plasma concentration (T_max), elimination half‐life (t_1/2β), mean residence time (MRT), and apparent volume of distribution (V_F) were 2.03 ± 0.37 hr, 29.31 ± 5.56 hr, 25.22 ± 2.57 hr, 4.06 ± 1.04 L/kg, and 3.05 ± 0.08 hr, 17.06 ± 1.77 hr, 15.55 ± 1.37 hr, 2.95 ± 0.62 L/kg after the orally administrated tilmicosin enteric granules and premix. The relative bioavailability of tilmicosin enteric granules to premix was 114.97 ± 7.19%, according to the AUC_0‐t values. These results demonstrated that tilmicosin enteric granules produced faster tilmicosin absorption, slower elimination, larger tissue distribution, and higher bioavailability compared to the tilmicosin premix. The present study results manifest that tilmicosin enteric granules can be used as a therapeutic alternative to premix in clinical treatment.