意大利蜜蜂工蜂幼虫饲粮中铜的适宜水平

本试验通过研究饲粮中铜水平对意大利蜜蜂工蜂幼虫生长发育、生理功能、抗氧化能力的影响,确定意大利蜜蜂工蜂幼虫饲粮中铜的适宜水平。选取1日龄意大利蜜蜂工蜂幼虫1440只,随机分成6组(每组10个重复,每个重复24只幼虫),分别饲喂铜添加水平为0(对照)、1.00、2.00、3.00、4.00和5.00μg/g的饲粮(实测饲粮铜水平分别为2.69、3.62、4.63、5.64、6.61和7.67μg/g),饲养至幼蜂羽化出房。分别取4、5、6日龄工蜂幼虫测定血淋巴生化指标、抗氧化酶活性和抗氧化相关基因相对表达量,并计算工蜂幼虫的化蛹率和羽化率。结果表明:1)饲粮中铜水平对化蛹率和羽化率有显著影响(P<0.05),羽化率在铜水平为3.62μg/g时达到最高,与对照组差异不显著(P>0.05),但显著高于5.64、6.61和7.67μg/g铜组(P<0.05)。2)饲粮中铜水平对血淋巴中总蛋白(TP)、总胆固醇(TCHO)含量有显著影响(P<0.05)。随着饲粮中铜水平的升高,6日龄工蜂幼虫血淋巴中TP、TCHO含量均持续下降。3)饲粮中铜水平对工蜂幼虫4、5和6日龄铜锌超氧化物歧化酶(Cu/Zn SOD)、6日龄谷胱甘肽过氧化物酶(GSH Px)以及6日龄铜蓝蛋白(CP)活性有显著影响(P<0.05)。随着饲粮中铜水平的升高,工蜂幼虫6日龄Cu/Zn SOD、GSH Px以及CP活性均呈现先升高后降低的趋势,且分别在铜水平为3.62、5.64、6.61μg/g时达到最高。4)饲粮中铜水平对5日龄工蜂幼虫过氧化氢酶(CAT)、Cu/Zn SOD基因的相对表达量有显著影响(P<0.05)。随着饲粮中铜水平的升高,5日龄工蜂幼虫CAT、Cu/Zn SOD基因的相对表达量呈现先增加后下降的趋势,且均在铜水平为3.62μg/g时达到最高。综述所述,饲粮中铜水平影响意大利蜜蜂工蜂幼虫的生长发育、生理机能以及抗氧化能力。分别对饲粮中铜水平与意大利蜜蜂工蜂幼虫的羽化率和6日龄GSH Px活性进行曲线拟合,得到意大利蜜蜂工蜂幼虫饲粮中铜的适宜水平为4.96~5.34μg/g。     

意大利蜜蜂工蜂幼虫饲粮的适宜赖氨酸水平

本试验旨在研究意大利蜜蜂工蜂幼虫饲粮的适宜赖氨酸水平,为探明意大利蜜蜂工蜂幼虫发育阶段的赖氨酸营养需要提供理论依据。选用1日龄意大利蜜蜂工蜂幼虫1 200只,随机分为5个组,每个组5个重复,每个重复48只。5组工蜂幼虫分别饲喂赖氨酸实测水平为6.08(对照)、11.08、16.08、21.08和26.08 mg/g的饲粮,饲养至幼蜂羽化出房。分别于特定日龄测定工蜂幼虫化蛹率(6日龄)、虫体总蛋白含量(6日龄)、羽化率(21日龄)等生长指标以及血淋巴生化指标和免疫相关指标(6日龄)。结果表明:1)11.08 mg/g赖氨酸组的工蜂幼虫化蛹率和羽化率极显著高于其他各组(P0.01)。2)与对照组相比,11.08~26.08 mg/g赖氨酸组6日龄工蜂幼虫虫体总蛋白含量和血淋巴中游离赖氨酸含量显著提高(P0.05),其中饲粮赖氨酸水平为26.08 mg/g时6日龄工蜂幼虫虫体总蛋白含量和血淋巴中游离赖氨酸含量最高。3)6日龄工蜂幼虫血淋巴中甘油三酯含量随饲粮赖氨酸水平的升高呈先下降后上升的趋势,其中饲粮赖氨酸水平为16.08 mg/g时处于最低值,极显著低于其他各组(P0.01)。4)11.08~21.08 mg/g赖氨酸组6日龄工蜂幼虫血淋巴中溶菌酶活性显著高于对照组(P0.05),但随着饲粮赖氨酸水平由21.08 mg/g升高到26.08 mg/g,6日龄工蜂幼虫血淋巴中溶菌酶活性急剧下降,26.08 mg/g赖氨酸组显著低于其他各组(P0.05)。5)饲粮赖氨酸水平为11.08 mg/g时,6日龄工蜂幼虫虫体溶菌酶基因的相对表达量最高,显著高于其他赖氨酸水平时(P0.05)。与对照组相比,11.08~16.08 mg/g赖氨酸组6日龄工蜂幼虫虫体防卫素1基因的相对表达量显著增加(P0.05)。由此得出,赖氨酸能够促进意大利蜜蜂工蜂幼虫生长,促进蛋白质和赖氨酸的沉积,提高羽化率,并在一定程度上对脂质代谢和幼虫免疫能力产生调节作用;综合考虑上述指标,推荐意大利蜜蜂工蜂幼虫饲粮的适宜赖氨酸水平为11.08~16.08 mg/g。     

意大利蜜蜂工蜂幼虫饲粮中适宜泛酸水平

本研究旨在探索饲粮中泛酸水平对意大利工蜂蜜蜂幼虫发育、机体抗氧化能力及辅酶A(Co A)合成相关酶基因表达的影响,以期得到蜜蜂幼虫阶段饲粮中泛酸的适宜水平。试验选取1日龄意大利蜜蜂工蜂幼虫1 800只,随机分为5组,每组3个重复,每个重复120只。5组工蜂幼虫分别饲喂泛酸实测水平为0.92(对照)、1.22、1.52、1.82、2.12 mg/g的试验饲粮,饲喂至化蛹。分别取5日龄和7日龄幼虫测定体重、体成分、血淋巴生化指标、抗氧化指标、Co A合成相关酶基因的相对表达量,并计算幼虫的化蛹率和羽化率。结果表明:1)饲粮中添加泛酸可显著提高虫体鲜重、干重以及粗脂肪含量(P0.05);当泛酸水平为2.12 mg/g时,幼虫的羽化率显著高于其他组(P0.05)。2)饲粮中泛酸水平对5日龄工蜂幼虫血淋巴中总蛋白(TP)、总胆固醇(TCHO)、高密度脂蛋白(HDL)、低密度脂蛋白(LDL)含量有显著影响(P0.05),且分别在1.82、1.82、1.22、1.52 mg/g组含量最低。3)5日龄和7日龄虫体总抗氧化能力(T-AOC)以及5日龄虫体超氧化物歧化酶(SOD)活性随饲粮泛酸水平的升高而显著升高(P0.05)。4)饲粮泛酸水平显著影响5日龄幼虫泛酸激酶4基因和磷酸泛酰-半胱氨酸脱羧酶基因的相对表达量(P0.05),且均在泛酸水平为1.82 mg/g时相对表达量最高。分别以5日龄虫体的干重和羽化率作拟合曲线,获得意大利蜜蜂工蜂幼虫饲粮中适宜的泛酸水平为1.85~2.01 mg/g。     

饲粮铜水平对冬毛期银狐铜表观生物学利用率及组织器官铜沉积量的影响

本试验旨在研究饲粮铜水平对冬毛期银狐铜表观生物学利用率及组织器官铜沉积量的影响。选择50只120日龄、平均体重为(5 134±540)g的健康雌性银狐,随机分成5组,每组设10个重复,每个重复1只银狐。各组分别饲喂在基础饲粮中添加6(Ⅰ组)、30(Ⅱ组)、60(Ⅲ组)、90(Ⅳ组)和150 mg/kg(Ⅴ组)柠檬酸铜的试验饲粮,基础饲粮中铜含量为4.92 mg/kg。预试期7 d,正试期51 d。结果表明:1)饲粮铜水平对平均日采食量、粪排出量和铜表观生物学利用率均无显著影响(P>0.05),对铜摄入量和粪铜排出量有极显著影响(P<0.01)。随着饲粮铜水平增加,铜摄入量和粪铜排出量极显著升高(P<0.01)。2)饲粮铜水平对毛铜、肝铜、肾铜和心铜沉积量均有极显著影响(P<0.01)。随着饲粮铜水平增加,毛铜沉积量呈升高趋势,Ⅴ组沉积量最高;各组间肝铜、肾铜和心铜沉积量未显现出规律性变化。3)饲粮铜水平对心脏重有显著影响(P<0.05),从Ⅱ组至Ⅴ组,心脏重呈降低趋势。饲粮铜水平对肝脏重、肾脏重和脾脏重无显著影响(P>0.05)。综合分析各项试验指标,得出银狐冬毛期基础饲粮中添加60 mg/kg柠檬酸铜(饲粮中铜含量约65 mg/kg)时,有利于银狐对铜的消化利用。     

43～63日龄黄羽肉公鸡铜需要量

本研究旨在通过研究饲粮铜添加水平对黄羽肉公鸡生长性能、抗氧化性能、肝脏和血清铜含量等的影响,以探讨43~63日龄黄羽肉公鸡铜的需要量。选用43日龄健康、发育良好的快大型岭南黄羽肉公鸡900只,根据体重随机分为6个组,每组6个重复,每个重复25只鸡,组1(对照组)为基础饲粮组(铜水平为2.74 mg/kg),组2~6饲粮在基础饲粮中分别添加4、8、16、32、64 mg/kg铜。结果表明:1)与对照组相比,16和32 mg/kg铜组显著提高试鸡末重、平均日增重和平均日采食量(P<0.05),饲粮中铜添加水平对料重比无显著影响(P>0.05)。2)与对照组相比,16和32 mg/kg铜组血清铜锌-超氧化物歧化酶(Cu Zn-SOD)活性显著升高(P<0.05),32和64 mg/kg铜组肝脏Cu Zn-SOD活性显著升高(P<0.05),饲粮铜添加水平对胸肌中Cu ZnSOD活性无显著影响(P>0.05);饲粮添加32和64 mg/kg铜显著降低了胸肌丙二醛(M DA)含量(P<0.05),各组间血清和肝脏MDA含量均无显著差异(P>0.05);添加16、32、64 mg/kg铜显著降低了血清铜蓝蛋白活性(P<0.05)。3)与对照组相比,8、16 mg/kg铜组肝脏铜含量显著降低(P<0.05),铜添加水平对血清铜含量和肝脏金属硫蛋白含量影响不显著(P>0.05)。综合考虑各项指标,为获得较好生长性能和抗氧化性能,43~63日龄黄羽肉公鸡饲粮铜适宜添加水平分别为16和32 mg/kg,加上基础饲粮铜水平为2.74 mg/kg,则该阶段黄羽肉公鸡铜需要量分别为18.74和34.74 mg/kg;以生长性能和肝脏Cu Zn-SOD活性为依据,通过折线回归分析估测得到43~63日龄黄羽肉公鸡铜需要量分别为19.94和38.34 mg/kg。     

锰对意大利蜜蜂幼虫生长发育和抗氧化能力的影响

微量元素对动物的生长发育和生产性能具有重要作用。有资料表明,蜜蜂的生长发育、繁殖需要微量元素锰的参与,锰还具有提高蜜蜂抗氧化能力、增强免疫的作用。为了进一步探明锰对蜜蜂生长发育和生理机能的影响,本研究以意大利蜜蜂(Apis mellifera L.)为研究对象,通过在蜜蜂幼虫饲粮中添加不同水平的锰,开展室内幼虫饲养试验,对蜜蜂生长发育、机体生理生化指标以及相关基因表达等进行测定和观察,力求探明锰对蜜蜂的营养作用及机制。从蜂群中移取2日龄(2d)意大利蜜蜂工蜂幼虫1200只,随机分成5组,每组5个重复,每个重复48只幼虫。其中1组为对照组,饲喂基础饲粮;其余4组为试验组,饲喂锰添加水平分别为2.00mg/kg、3.00mg/kg、4.00mg/kg、5.00mg/kg的基础饲粮。将2d工蜂幼虫置于室内恒温恒湿培养箱中培养,温度为34℃,湿度为50%±5%,化蛹前每日更换饲料,饲养至羽化出房。分别采集3d、5d、7d幼虫样本,测定生理生化指标和相关基因表达水平;统计各组化蛹率、羽化率。经统计分析,结果表明:(1)与对照组相比,幼虫饲粮中锰添加水平为3.00mg/kg、4.00mg/kg时,锰能够提高意大利蜜蜂幼虫化蛹率和羽化出房率。(2)锰对意大利蜜蜂幼虫抗氧化酶活性影响显著,当幼虫饲粮中锰添加3.00mg/kg和4.00mg/kg时,幼虫体内的抗氧化酶显著升高(P<0.05)。(3)锰对意大利蜜蜂幼虫抗氧化酶相关基因表达量的影响显著(P<0.05)。当幼虫饲粮中锰添加4.00mg/kg时,幼虫体内的抗氧化酶基因表达量显著上升(P<0.05)。本研究表明,饲粮中的锰水平影响蜜蜂的生长发育和生理机能。意大利蜜蜂幼虫饲料中补充适量的锰时,且锰的添加水平大约在2.96mg/kg时,能够提高幼虫的抗氧化能力。     

爱拔益加肉鸡对饲粮中添加的辣木提取物的耐受性评价

本试验旨在研究饲粮中添加高剂量(10.00 g/kg)辣木提取物对爱拔益加(AA)肉鸡生长性能、抗氧化功能、血液学指标、脏器指数、消化及免疫系统各器官组织病理学的影响,以确定辣木提取物在肉鸡饲粮中的安全添加限量。选用平均体重为(45±2) g、健康1日龄AA肉鸡288只,随机分为3个组,每组6个重复,每个重复16只鸡。试验采用玉米-豆粕-杂粕型基础饲粮,对照组饲喂基础饲粮,试验组饲喂分别在基础饲粮中添加0.75和10.00 g/kg辣木提取物的饲粮。试验期42 d。结果表明:1)饲粮添加0.75和10.00 g/kg辣木提取物显著提高了肉鸡平均日增重(P0.05),但对平均日采食量和料重比无显著影响(P0.05);2)饲粮添加0.75和10.00 g/kg辣木提取物显著提高了42日龄肉鸡血清总抗氧化能力(P0.05),显著降低了血清丙二醛含量(P0.05);3)饲粮添加0.75 g/kg辣木提取物显著提高了21日龄肉鸡血小板平均体积(P0.05),饲粮添加0.75和10.00 g/kg辣木提取物显著提高了21日龄肉鸡血小板分布宽度(P0.05);4)饲粮添加0.75和10.00 g/kg辣木提取物可以降低肉鸡的死淘率到3.13%和2.08%;5)饲粮添加10.00 g/kg辣木提取物对肉鸡消化和免疫器官的组织结构未见明显影响。综上,饲粮添加辣木提取物可以提高肉鸡的增重,提高肉鸡的抗氧化功能,降低肉鸡死淘率,2个添加剂量间也有改善的趋势。因此,辣木提取物在肉鸡饲粮中添加量≤10.00 g/kg是安全的。     

钙锌对蛋用型鸡育成期体组织中矿物元素含量的影响

试验研究了在玉米—豆饼型基础饲粮中添加不同水平锌和钙对蛋用型鸡育成期体组织中矿物元素含量的影响。结果表明,随着饲粮锌水平的提高,肝脏(P<0.01)、肾脏(P<0.05)、胰脏(P<0.01)中锌含量显著升高,而肺脏中锌含量没有显著变化(P>0.05)。饲粮高钙对组织中锌含量的影响未达到显著水平(P>0.05)。饲粮高锌使肝脏磷含量(P<0.05)、肾脏磷(P<0.01)和铜含量(P<0.05)、肺脏钙(P<0.01)和镁含量(P<0.01)显著降低。饲粮商钙使胰脏铜含量(P<0.05)显著提高,使胰脏锰含量显著降低(P<0.05)。     

意大利蜜蜂工蜂幼虫饲粮中亚油酸的适宜添加水平

本试验旨在研究意大利蜜蜂工蜂幼虫饲粮中亚油酸的适宜添加水平。选取576只1日龄的工蜂幼虫,随机分为6组,每组96只幼虫,对照饲喂基础饲粮,试验组分别饲喂添加0.02%、0.04%、0.06%、0.08%和0.10%亚油酸的饲粮,试验期7 d。结果表明:1)与对照组相比,饲粮添加0.10%亚油酸显著降低了化蛹率(P0.05)。2)与对照组相比,饲粮添加0.04%亚油酸显著提高了5日龄虫体蛋白质浓度(P0.05);饲粮中添加0.10%亚油酸显著降低了7日龄蛹蛋白质浓度(P0.05)。3)与对照组相比,饲粮添加0.02%亚油酸对6日龄虫体的过氧化物酶增殖物激活受体(PPAR)α活性有显著的抑制作用(P0.05),添加0.08%的亚油酸则显著提高了6日龄虫体PPARα和PPARγ活性。4)与对照组相比,饲粮添加0.04%和0.08%亚油酸显著提高了6日龄虫体脂肪酸合成酶(FAS)活性(P0.05);添加0.08%亚油酸显著提高了5日龄虫体乙酰辅酶A羧化酶(ACC)浓度(P0.05),添加0.06%和0.10%亚油酸显著提高了6日龄虫体ACC浓度(P0.05)。5)饲料中添加本试验设定范围的亚油酸对幼虫FAS和ACC基因相对表达量无显著影响(P0.05)。综合化蛹率和虫体蛋白质浓度2个指标的拟合曲线结果,认为意大利蜜蜂工蜂幼虫饲粮中亚油酸的适宜添加水平为0.024%~0.037%。     

饲粮中添加竹青素对肉鸡脂质代谢的影响

本试验在饲粮中添加一定比例的竹青素(green bamboo extract,GBE)饲喂石岐胡须鸡,研究GBE对肉鸡脂质代谢的影响。选取26日龄石岐胡须鸡仔鸡360只,随机分成4组(每组3个重复,每个重复30只鸡):对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮中添加1.5、3.0和6.0 g/kg GBE的试验饲粮,试验期49 d。结果表明:与对照组相比,饲粮中添加1.5、3.0 g/kgGBE显著降低肉鸡的腹脂率(P<0.05),添加1.5、6.0 g/kg GBE极显著降低皮下脂肪厚度(P<0.01),添加6.0 g/kg GBE极显著降低肝脏脂肪含量(P<0.01)。与对照组相比,饲粮中添加3.0 g/kg GBE极显著降低血清甘油三酯的含量(P<0.01),但添加GBE对体重、血清总胆固醇和低密度脂蛋白胆固醇含量无显著影响(P>0.05)。与对照组相比,饲粮中添加1.5、3.0 g/kgGBE显著提高血清中瘦素含量(P<0.05),添加3.0 g/kg GBE显著提高血清中脂联素含量(P<0.05)。与对照组相比,饲粮中添加1.5、3.0 g/kg GBE极显著提高血清中超氧化物歧化酶活性(P<0.01),极显著降低血清中丙二醛含量(P<0.01),添加3.0 g/kg GBE极显著提高血清中谷胱甘肽过氧化物酶活性(P<0.01)。综上所述,饲粮中添加GBE饲喂肉鸡可起到显著的降脂作用,添加3.0 g/kg GBE效果最佳。     

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.     

In Vitro Evaluation of the Effects of Selected Plants on the Growth of the Mycelial Form of Histoplasma capsulatum Variety farciminosum in Ethiopia

Epizootic lymphangitis is prevalent in equines in Ethiopia, causing remarkable economic and welfare impacts but often neglected. Lack of effective treatment contributed to its continued occurrence, and hence, search for an effective treatment should be considered a priority area to minimize its impacts. Previous ethnobotanical studies have reported that Curcuma longa, Phytolacca dodecandra, and Datura stramonium were used to treat cutaneous fungal infections and reduce their incidence. The treatment effects of these plants against epizootic lymphangitis should be studied. The in vitro growth inhibitory effects of methanol extracts of the root of C. longa, berry of P. dodecandra, and leaf of D. stramonium were evaluated. Histoplasma capsulatum var farciminosum was isolated from clinical cases of epizootic lymphangitis in carthorses in central Ethiopia. The nested polymerase chain reaction was used to confirm the identity of the isolates. Serial twofold dilutions of the extract of berries of P. dodecandra and leaves of D. stramonium were done in sterile water, whereas dilution of the extract of roots of C. longa was done in dimethylsulphoxide. The effects of the plants on the growth of Histoplasma capsulatum var farciminosum were assessed by agar dilution assay. Culture media with no antifungal agent and media containing ketoconazole served as negative and positive control, respectively. The methanol extract of C. longa showed inhibitory effects at concentrations ranging from 0.07 to 5 mg/mL. Similarly, the methanol extract of P. dodecandra showed growth inhibitory effects at concentrations ranging from 0.156 to 5 mg/mL. That is, the growth inhibitory concentration of C. longa was 0.07 mg/mL, whereas that of P. dodecandra was 0.156 mg/mL. In contrast, D. stramonium showed no inhibitory effect. This preliminary observation showed that methanol extracts of C. longa and P. dodecandra showed inhibitory effects on the growth of Histoplasma capsulatum var farciminosum requiring further repeated in vitro evaluation so as to generate adequate evidence, which would justify in vivo trials.     

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).     

Effects of the ruminal comminution rate and microbial contamination of particles on accuracy of in situ estimates of ruminal degradability and intestinal digestibility of feedstuffs

Effects of considering the comminution rate (k_c) and the correction of microbial contamination (using ¹⁵N techniques) of particles in the rumen on estimates of ruminally undegraded fractions and their intestinal digestibility were examined generating composite samples (from rumen‐incubated residues) representative of the undegraded feed rumen outflow. The study used sunflower meal (SFM) and Italian ryegrass hay (RGH) and three rumen and duodenum cannulated wethers fed with a 40:60 RGH to concentrate diet (75 g DM/kgBW^0.75). Transit studies up to the duodenum with Yb‐SFM and Eu‐RGH marked samples showed higher k_c values (/h) in SFM than in RGH (0.577 vs. 0.0892, p = 0.034), whereas similar values occurred for the rumen passage rate (k_p). Estimates of ruminally undegraded and intestinal digestibility of all tested fractions decreased when k_c was considered and also applying microbial correction. Thus, microbial uncorrected k_p‐based proportions of intestinal digested undegraded crude protein overestimated those corrected and k_c?k_p‐based by 39% in SFM (0.146 vs. 0.105) and 761% in RGH (0.373 vs. 0.0433). Results show that both k_c and microbial contamination correction should be considered to obtain accurate in situ estimates in grasses, whereas in protein concentrates not considering k_c is an important source of error.     

Effects of oral administration of different dosages of carvacrol essential oils on intestinal barrier function in broilers

Essential oils are widely used in the pharmaceutical, food and cosmetic industries, and many plant essential oils have shown that they have positive effects on broilers nutrition. This experiment was conducted to study the effects of orally administered different dosages of carvacrol essential oils on intestinal barrier function in broiler chickens. A total of eighty 28‐day‐old (1.28 ± 0.15 kg) ROSS 308 broilers were randomly allocated to four groups of 20 replicates each, with one chicken per replicate per cage, and all were fed with the same diet. Four experimental groups were orally administered 0, 200, 300 or 400 μl carvacrol essential oils at 18:00 hr every day during the 2‐week experimental period. As a result of which, the gene expression of the occludin, claudin‐1, claudin‐5, ZO‐1 and ZO‐2 in intestinal mucosa of small intestine (p < 0.05) and the goblet cell content in small intestine epithelium (p < 0.05) were significantly increased; test subjects with 300 or 400 μl carvacrol essential oils reduced the microbial counts of Salmonella spp. and Escherichia coli in the intestines (p < 0.05); Essential oils administration also significantly increased activity of the sucrase (p < 0.05) and lactase (p < 0.05) in intestinal mucosa. In conclusion, the carvacrol essential oils have positive effects on growth performance and intestinal barriers function of broilers; those effects may be related to the dosage, as administration of 300 or 400 μl was more effective than that of 200 μl.     

Effects of oral supplementation of probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium on diarrhoea events of foals in their first weeks of life

Foal first diarrhoea is one of the most prominent problems in the early life of horses. Probiotics might have the potency to prevent or at least diminish neonatal diarrhoea. We hypothesised that the treatment of foals with probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium starting early after birth and then daily over 2 weeks would prevent or mitigate foal heat diarrhoea. The influence of this probiotic treatment on diarrhoea incidence and growth and health performance of young foals was investigated. Thirty‐four foals were randomly allocated to two groups. From day 1 to 14 of life, the foals received either placebo (PG, n = 16) or the probiotic treatment (TG, n = 18). Clinical examination was performed, and the faeces consistency score (FCS, 1–5; with diarrhoea defined by ≤3) was recorded once per day in weeks 1 and 2 and once weekly in weeks 3–8 of life (WL). The body height was measured at birth and after two and eight WL. Diarrhoea occurred in the 1st WL in 19% and 61% of PG and TG foals respectively. In the 1st WL, diarrhoea lasted 0.3 ± 0.8 and 1.6 ± 1.4 days in PG and TG foals respectively. In the 2nd WL, diarrhoea occurred in 94% and 84% of PG and TG foals, respectively, and lasted for 3.0 ± 1.5 and 3.7 ± 1.6 days respectively. At least two periods of diarrhoea developed in 33% and 65% of PG and TG foals respectively. The TG foals grew slightly slower than the PG foals. The results indicated that the probiotic treatment of neonatal foals as performed in this study was not suitable to reduce diarrhoea within the first two WL, because contrary to the hypothesis, the TG foals suffered more frequently and for longer periods from diarrhoea than the PG foals.     

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.     

Influence of a flooding dose of valine on key indicators of metabolic status in the growing pig

A key concern with the flooding dose technique for measuring protein synthesis is that a large dose of amino acid (AA) can potentially change the animals’ hormonal and nutritional status, which in turn can influence protein synthesis. Among stable isotope tracers, 1‐[¹³C]‐valine is the preferred AA for measuring protein synthesis in gut tissue and mucins. A study was conducted to determine the impact of a flooding dose of valine on the metabolic status of pigs. Six barrows [16.5 kg body weight (BW)] were randomly assigned to intravenous infusions of either 150 mm valine (1.5 mmol/kg BW) or physiological saline, following a crossover design. Blood samples were taken 10 min prior to infusion, at the end of infusion, at 10‐min intervals for 60 min post‐infusion, and at 90 and 120 min post‐infusion. Plasma concentrations of insulin, glucose, AA, urea nitrogen and packed cell volume (PCV) were measured. Infusion of valine increased plasma valine concentrations (4129 vs. 582 μm ; P < 0.05) but had no influence on PCV (26.4% vs. 27.2%) and plasma concentrations of glucose (6.0 vs. 5.8 mm ) and insulin (8.2 vs. 8.5 μU/ml; P > 0.10). Plasma urea nitrogen concentration was reduced with valine infusion (8.5 vs. 7.8 mg/dl; P < 0.05). A flooding dose of valine had no impact on plasma concentrations of AA, and specifically branched‐chain AA such as leucine (240 vs. 231 μm ) and isoleucine (310 vs. 331 μm ; P > 0.10). There was, however, a slight increase in the plasma concentrations of threonine (224 vs. 263 μm ; P < 0.05) and a tendency towards reduced glycine (1387 vs. 1313 μm ; P < 0.10). The results indicate that a flooding dose of valine does not cause a substantial change in the metabolic status of growing pigs and is therefore suitable for measuring protein synthesis rates.     

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.