北方寒区环境温度对中国荷斯坦牛乳清中某些生化指标的影响

为了探讨动物在不同环境温度时 ,乳样中某些生化指标变化的规律性 ,以健康荷斯坦奶牛为试验对象 ,研究不同环境温度下 (5℃、10℃、15℃、2 0℃、2 5℃ )对奶牛乳清的某些生化指标的影响。研究结果表明 ,环境温度为 2 0℃时 ,乳清天门冬氨酸氨基转移酶 (AST)活性最高 ,显著高于其它各组 ;乳清肌酸激酶 (CK)活性在 5℃和 2 5℃时极显著高于各中间温度组 ;丙氨酸氨基转移酶 (ALT)从 5℃至 2 0℃逐渐升高 ,且 2 0℃组显著高于 2 5℃组 ;乳清总蛋白 (TP)含量 5℃组为最低 ,而 10℃、15℃和 2 5℃组为高 ;乳清中尿素氮 (BUN)则随环境温度的升高呈逐渐降低的趋势 ,且 2 5℃组显著低于其它各温度组。上述实验结果可能说明外界环境温度的变化 ,可对泌乳奶牛乳清中的某些酶活性及代谢成分具有显著影响。     

不同发酵温度对液体发酵饲料营养成分、挥发性脂肪酸和活菌数的影响

文章旨在研究不同发酵温度对液体发酵饲料营养成分、挥发性脂肪酸和活菌数的影响。试验分别设定20、25、30℃三个发酵温度，每个发酵温度设置6个重复，厌氧发酵24?h。试验结果表明，随着发酵温度的升高，饲料中粗蛋白质含量显著提高（P <0.05），粗纤维含量无显著变化（P> 0.05），但总能显著降低（P <0.05）;25和30℃发酵时，液体饲料中乳酸含量显著高于20℃组（P <0.05），但25和30℃之间差异不显著（P> 0.05）；而挥发性脂肪酸方面，25和30℃发酵时，饲料中乙酸和丙酸含量显著高于20℃发酵组（P <0.05），而25和30℃之间的丙酸含量差异不显著（P> 0.05），乙酸含量25℃发酵组高于30℃发酵组（P <0.05）。丁酸含量则随发酵温度升高而显著降低（P <0.05）；液体饲料中的乳酸菌和酵母菌活菌数显著升高（P <0.05），其中25和30℃发酵组酵母菌活菌数无显著差异（P> 0.05）；液体饲料中均未检出沙门氏菌和大肠杆菌。     

不同温度及突变方式对菲律宾蛤仔耗氧率的影响

本研究采用静水法测定了不同温度及急性温度突变对菲律宾蛤仔耗氧率的影响,分别在5个恒定温度（15、20、25、30和35℃）以及4个急性温度突变（分别由25℃突变至15、20、30和35℃）条件下测定了菲律宾蛤仔的耗氧率。试验结果表明,温度对菲律宾蛤仔的耗氧率具有显著性影响（P＜0.05）。在温度为15～30℃内时,耗氧率随温度的升高而逐渐增大,随着温度的继续升高达到35℃时耗氧率开始下降。方差分析表明,耗氧率在15℃时最低,与20℃组和35℃组之间差异不显著（P＞0.05）;在30℃时耗氧率最大,与25℃组无显著性差异,但显著高于15℃和20℃组（P＜0.05）。温度突变后菲律宾蛤仔耗氧率相比于恒温状态下均出现不同程度提高,说明温度骤变环境下菲律宾蛤仔要消耗更多的能量。     

稀释倍数对湖羊精液低温保存效果的影响

为探究稀释倍数对湖羊精液4℃保存的影响，本实验使用3只1～2岁体况良好的公羊，将采集的精液稀释2、5、10、15、20、25倍后，检测4℃保存过程中精子活率、活力、运动速率以及质膜完整性和顶体完整性。结果表明：保存3～5 d,10倍稀释保存的精子活率和活力显著高于其他各组；保存1～4 d,25倍高倍稀释的精子活力下降最快，且显著低于其他组；保存1～3 d,10倍稀释保存的精子曲线速率（VCL）和路径速率（VAP）显著高于20和25倍稀释组；保存期间，10倍稀释保存的精子质膜完整性最高，且在第4天显著高于其他组；保存3～5 d,5和10倍稀释保存的精子顶体完整性显著高于15～25倍稀释组。因此，在本实验条件下，5～10倍为湖羊精液4℃保存的最适宜稀释倍数，过低或者过高的稀释倍数都不利于湖羊精液4℃保存。     

环境温度和日粮能量水平对鸡血浆皮质酮水平的影响

本试验使用６×２因子设计，研究了环境温度（５℃～３５℃，６个处理）和日粮能量浓度（２．８和３．２Ｍｃａｌ／ｋｇ，２个水平）对巴布考克型种公鸡血浆皮质酮水平的影响。结果表明：环境温度高于２５℃时，鸡血浆皮质酮水平显著升高且随温度的升高而升高，而当环境温度下降至５℃～２５℃时，血浆皮质酮水平没有显著变化；日粮能量浓度对鸡血浆皮质酮水平没有显著影响     

舍外温湿度对荷斯坦奶牛生产性能及酶活性影响的研究

以荷斯坦奶牛为试验对象,研究不同环境温度、湿度对奶牛生产性能及血液乳清酶活性的影响。研究结果表明:随着环境温度的季节性下降和舍内湿度的升高,血清及乳清ALT、AST和ALP活性下降;血清和乳清中CK活性升高;血清LDH活性升高,乳清LDH活性降低;建议舍内温度5.5℃±0.5,相对湿度80%为宜。     

舍外温湿度对荷斯坦奶牛生产性能及酶活性影响的研究

以荷斯坦奶牛为试验对象,研究不同环境温度、湿度对奶牛生产性能及血液乳清酶活性的影响.研究结果表明随着环境温度的季节性下降和舍内湿度的升高,血清及乳清ALT、AST和ALP活性下降;血清和乳清中CK活性升高;血清LDH活性升高,乳清LDH活性降低;建议舍内温度5.5℃±0.5,相对湿度80%为宜.     

若尔盖不同退化程度高寒沼泽湿地土壤氮矿化特征及温度效应

为明晰退化高寒沼泽湿地土壤氮矿化及其对气候变暖的响应，本研究采用淹水培养法研究相对原生沼泽（RPM）向轻度退化沼泽（LDM）、中度退化沼泽（MDM）、重度退化沼泽（HDM）退化过程中土壤氮矿化特征及温度效应。结果表明：不同退化程度土壤铵态氮累积量、氨化速率和氮矿化势的大小都是MDM>RPM>LDM>HDM；退化沼泽土壤氨化速率相较于RPM在5~15℃时减慢，在20~25℃时加快；4种湿地土壤铵态氮累积量和氨化速率均随温度升高而增大；沼泽退化降低了氮矿化的温度敏感系数，且HDM显著高于LDM和MDM。因此，在若尔盖多年月均气温低于15℃的条件下，高寒沼泽湿地退化降低了土壤氨化速率、供氮潜力和氨化作用的温度敏感性，减小了土壤氮的可利用性。     

硒对汞致雏鸡肝功能损伤的拮抗作用

选用健康伊沙褐雏鸡250只，分为对照组、汞中毒组、3个水平的硒保护组，研究汞对血清中门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）、碱性磷酸酶（ALP）、肝组织中谷胱甘肽过氧化物酶（GSH－Px）活性和丙二醛（MDA）含量的影响以及硒与汞之间的相互作用效应。试验结果表明，汞可使血清中AST、ALT、ALP活性显著升高（P＜0．01），使肝组织中GSH－Px活性降低（P＜0．01），引发肝组织脂质过氧化，致使肝组织中MDA含量显著增高（P＜0．01），且有时间－效应关系，硒可使血清中AST、ALT、ALP活性显著降低（P＜0．01），使肝组织中GSH－Px活性显著升高（P＜0．01），阻止肝组织脂质过氧化，致使肝组织中MDA含量显著降低（P＜0．01），且有时间－效应关系，从而说明汞中毒损伤肝功能；硒对汞致肝功能的损伤具有拮抗作用。     

不同温度条件下发酵时间对完全混合发酵日粮(TMF)发酵品质的影响

本试验旨在研究不同温度条件下，发酵时间对完全混合发酵日粮（total mixed fermentation ration，TMF）发酵品质的影响。将0.5% CT-10（同型发酵乳酸杆菌）、5%糖蜜和TMR装入发酵袋内并于5、15和25℃条件下密封发酵，在发酵5、10、15、20和30 d时开袋取样测定其发酵品质。结果显示：5℃时，随着发酵时间的延长，各组间中性洗涤纤维（NDF）和粗灰分（Ash）无显著差异（P > 0.05），而干物质（DM）、粗蛋白质（CP）、粗脂肪（EE）和酸性洗涤纤维（ADF）含量均随时间的增加而显著降低（P < 0.05）；15℃时，各组间NDF含量无显著差异（P > 0.05），而其他指标含量均呈现下降趋势；25℃时，各组间EE、Ash、NDF和ADF无显著差异（P > 0.05），而CP随着发酵时间的增加显著降低（P < 0.05）。不同的发酵时间对TMF有机酸含量影响显著（P < 0.05），在5和15℃时，发酵30 d天时pH分别降至4.23和4.36，达到发酵过程中的最低点；各个发酵温度条件下，氨态氮（NH₃-N）含量变化趋势一致，前15 d持续增加，之后又呈现先缓慢降低再增加的趋势；25℃时，发酵20 d，pH降至4.57，乳酸含量和TVFAs含量分别达到最高。综合以上结果和V-Score评分最终得出：5℃时，发酵20 d效果较好，15℃时，发酵15、20 d效果较好；25℃时，发酵5 d效果较好，饲料等级均为优。     

Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).     

Heartworm in dogs in Canada in 1985

In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).

Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1989

In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.

Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.

     

Heartworm in dogs in Canada in 1986

In late December 1986, 1224 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1986; 46% of them responded. Veterinarians reported that 150,989 dogs were blood-tested for microfilariae and 869 dogs were found with heartworm. Another 65 dogs were amicrofilaremic but diagnosed with heartworm disease and one was found with heartworm at necropsy to give the total number diagnosed in 1986 as 935 (0.62%).

Heartworm was reported from Manitoba, New Brunswick, Ontario and Quebec, but most (810) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 103 cases reported from Quebec, mostly from and around Montreal, and 21 cases from Manitoba, from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 33% of the cases were observed with clinical signs of heartworm disease and 81% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1987

In late November 1987, 1246 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1987, and 50% of them responded. Veterinarians reported that 165,428 dogs were blood tested for heartworm disease and 511 dogs were found with D. immitis microfilariae. Another 78 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1987 as 589 (0.35%).     

Heartworm in dogs in Canada in 1984

In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.

Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.

     

Heartworm in dogs in Canada in 1983

In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.

Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.