热应激对肉鸡试验性大肠杆菌病发病过程的影响

研究37℃热应激对肉鸡试验性大肠杆菌病发病过程的影响。结果表明,热应激条件下感染大肠杆菌肉鸡比单纯感染大肠杆菌肉鸡的临床症状出现晚、持续时间短,脏器病变率降低,死亡率极显著下降(P<0.01)(10%,55%),体温和呼吸频率极显著升高(P<0.01)。结论:37℃热应激在一定程度上可能会阻断肉鸡大肠杆菌病的发病过程。     

37℃持续热应激对肉鸡动脉压的影响

80羽25日龄商品代雄性AA肉鸡随机分为对照组(21℃~24℃,相对湿度50%±5%)和试验组(37℃±0.5℃,相对湿度70%±5%),动态监测各组肉鸡的股动脉压(FAP)和生产性能等指标。热暴露使肉鸡平均股动脉压、股动脉收缩压和股动脉舒张压极显著下降(P<0.01);平均股动脉压与呼吸频率、体温呈极显著负相关(P<0.01)。结果表明,37℃持续热应激使肉鸡的股动脉压极显著下降,股动脉压的变化与肉鸡对热暴露的反应和适应过程密切相关。     

大蒜素对热应激肉鸡血流动力学的影响

为了探讨大蒜素对热应激肉鸡血流动力学的影响,试验将240只23日龄AA肉鸡随机分为4组,分别为常温对照组、常温大蒜组、热应激组和热应激大蒜组,隔日测定股动脉压、红细胞比容及心脏脏器指数。结果表明:常温大蒜组的平均股动脉压在第4天开始显著或极显著低于常温对照组(P0.05或P0.01),红细胞比容在第8天开始极显著低于常温对照组(P0.01)。热应激大蒜素组的平均股动脉压在第4天极显著低于热应激组(P0.01),而在第12天显著高于热应激组(P0.05);红细胞比容在第6天极显著低于热应激组(P0.01),第12天极显著高于热应激组(P0.01)。     

高盐负荷诱发肉鸡肺动脉高压-腹水综合征

为探讨肺动脉高压在高盐负荷所致肉鸡腹水综合征发生发展的作用。将160只AA商品代肉仔鸡常规饲养至7日龄,随机分成对照组和试验组(饮水中添加0.30%氯化钠),分别于处理后1、2、3、4、5、6周,每组随机抽取8只鸡,利用右心导管法测定平均肺动脉压(mPAP),用温氏法检测红细胞压积(PCV),同时测定腹水心脏指数(AHI),统计腹水发生率。结果表明:(1)高盐负荷诱发肉鸡肺动脉高压,高盐处理1周试验组肉鸡肺动脉压升高为2.91±0.29kPa,显著高于对照组2.18±0.40kPa(P<0.05);并在整个处理期间持续升高,均显著(P<0.05)或极显著(P<0.01)地高于对照组;(2)高盐负荷诱发肉鸡AS,整个试验期间试验组的累计腹水发生率(16.3%)极显著高于对照组(2.5%)(P<0.01);(3)自分组后1周试验组的红细胞压积显著(P<0.05)或极显著(P<0.01)高于对照组,且与mPAP极显著相关(15～50日龄,r=0.612,P<0.01);(4)高盐负荷诱发肉鸡右心肥大,处理后2周试验组的AHI显著增高(P<0.05),与mPAP显著相关;并在整个处理期间相关程度逐渐密切(22日龄,r=0.532,P<0.05;50日龄,r=0.756,P<0.01)。这些结果说明肺动脉高压是高盐负荷所致肉鸡AS的中心环节,并且与右心肥大密切相关。     

丁酸梭菌早期干预对大肠杆菌攻毒肉鸡肠道炎症因子和抗菌肽基因表达的影响

为研究丁酸梭菌(CB)早期干预对大肠杆菌攻毒肉鸡肠道炎症因子和抗菌肽基因表达的影响,本试验选用健康的1日龄肉鸡200只,在1～3 d时,随机选择100只每天灌喂1 mL浓度为109cfu/mL的丁酸梭菌,另外100只灌喂1 mL生理盐水。在7日龄阶段,生理盐水灌喂肉鸡分成:对照组和大肠杆菌组(EC);丁酸梭菌处理肉鸡分成:丁酸梭菌组(CB组)和丁酸梭菌+大肠杆菌组(CB+EC组),其中EC组和CB+EC组均分别灌喂1 mL 108cfu/mL产肠毒素大肠杆菌菌液进行攻毒,而对照组和CB组则灌喂1 mL生理盐水。ETEC攻毒后记录鸡群的下痢情况,分别于攻毒后第3天(10日龄)和7天(14日龄)屠宰取回肠组织,实时荧光定量检测炎症因子和抗菌肽基因的表达。结果显示:(1)大肠杆菌攻毒后,丁酸梭菌灌喂的雏鸡均未出现死亡的情况,对照组和大肠杆菌组中雏鸡死亡率为3%。鸡群在灌喂大肠杆菌后出现了明显的下痢,大肠杆菌组下痢率为73.52%,而丁酸梭菌早期干预使得大肠杆菌攻毒引起的下痢率降低为29.41%。(2)在回肠组织中,攻毒3 d后,CB组与EC组和EC+CB组相比,IL-8和TLR4基因的表达量显著降低(P 0.05),而IL-10基因的表达量显著升高(P 0.05)。攻毒7 d后,CB组IL-10的表达量显著高于EC组(P 0.05),而对照组和CB组TLR4的表达量显著低于EC组与CB+EC组(P 0. 05)。(3)对于肠道抗菌肽基因的表达水平,攻毒3 d后,CB组回肠组织AvBD10表达量极显著高于其他处理组(P 0.01)。攻毒7 d后,CB组与EC组AvBD9的表达量显著高于其他组(P 0.01),CathB1表达量各处理组均显著增加(P 0.01)。综上所述,丁酸梭菌早期干预可以在一定程度上降低大肠杆菌攻毒肉鸡肠道中的炎症反应和提高抗菌肽基因的表达,从而减少大肠杆菌引起的下痢。     

日粮不同DDGS水平添加复合酶制剂对1～28日龄科宝肉鸡生长性能和死淘率的影响

试验旨在探究在添加复合酶制剂的前提下,考察不同玉米DDGS水平对1～28日龄科宝肉鸡生长性能和死淘率的影响。试验共选用1日龄健康体重相近的科宝肉鸡9 000只随机分为3组(对照组、A组和B组),每组6个重复,每个重复500只鸡(公母各半)。试验共分为1～7 d和8～28 d两个阶段进行,每阶段各试验组DDGS的添加水平分别为:1～7 d:6.5%、10%、15%;8～28 d:7%、15%和20%。试验结果表明:1～7 d,各组间生长性能和欧洲效益指数无显著差异(P>0.05),A组和B组的死淘率及饲料中硫酸盐浓度显著高于对照组(P<0.05),B组饲料含粉率显著高于对照组;8～28 d,B组28 d末重显著低于对照组(P<0.05),料重比和死淘率显著高于对照组(P<0.05),A组和B组饲料含粉率及饲料中硫酸盐浓度显著高于对照组(P<0.05);全期,随着日粮DDGS水平增加,生长性能、欧洲效益指数显著降低(P<0.05),死淘率显著增加(P<0.05)。综上所述,在1～28 d肉鸡料中使用15%的DDGS并添加复合酶制剂可用于替代部分玉米和豆粕而对肉鸡生长性能无显著影响。此外,日粮高水平(>15%)DDGS会降低饲料的颗粒质量,增加日粮中硫酸盐浓度,最终影响肉鸡生长性能,提高肉鸡死淘率。     

富硒乳酸菌对饲喂黄曲霉毒素日粮肉鸡生产性能和抗氧化功能的影响

为研究富硒乳酸菌拮抗黄曲霉毒素对肉鸡生产性能和抗氧化功能的影响,选取150羽1日龄雄性AA肉鸡,随机均分成3组,对照组饲喂基础日粮,攻毒组和富硒乳酸菌组分别饲喂添加100μg/kg黄曲霉毒素B1(AFB1)的日粮及同时添加100μg/kg AFB1和3.33%富硒乳酸菌的日粮。预试验7 d,正式试验30 d。统计试验全期的生产性能指标,并测定试验第10、20和30天的血清抗氧化指标。结果显示:富硒乳酸菌组和对照组的末重和日增重均显著高于攻毒组(P<0.05),而料重比均极显著低于攻毒组(P<0.01);试验第10、20和30天时,富硒乳酸菌组和对照组血清谷胱甘肽过氧化物酶(GPX)和超氧化物歧化酶(SOD)活性均极显著或显著高于攻毒组(P<0.01或P<0.05),而丙二醛(MDA)含量均极显著低于攻毒组(P<0.01)。结果提示:富硒乳酸菌具有提高黄曲霉毒素导致的肉鸡生产性能下降和抗氧化功能降低的作用。     

雉鸡与AA~+肉鸡生长、屠宰、免疫、肠道菌群及肉品质的比较研究

研究旨在探讨雉鸡与AA~+肉鸡生长性能、屠宰性能、免疫性能、肠道菌群及肉品质之间的差异。试验选用成年雄性环颈雉与AA~+肉鸡各50只,分为2个处理组(每个处理组设置5个重复,每个重复10只鸡)。试验分为预饲期(7 d)与正式饲养期(14 d)2个阶段共21 d。结果表明:雉鸡的日增重极显著地低于AA~+肉鸡(P0.01),雉鸡的采食量极显著地低于AA~+肉鸡(P0.01),雉鸡的料肉比极显著地高于AA~+肉鸡(P0.01);雉鸡的全净膛率显著地高于AA~+肉鸡(P0.01),雉鸡的屠宰率、胸肌率与腿肌率均高于AA~+肉鸡,但没有显著性差异(P0.05)。雉鸡腹脂率极显著地低于AA~+肉鸡(P0.01);雉鸡的脾脏指数极显著地低于AA~+肉鸡(P0.01),雉鸡血清中的球蛋白数量显著地低于AA~+肉鸡(P0.05);雉鸡肠道内的大肠杆菌数量与乳酸菌数量均显著地高于AA~+肉鸡(P0.05),雉鸡肠道内双歧杆菌的数量显著地低于AA~+肉鸡(P0.05)。雉鸡肌肉剪切力极显著地高于AA~+肉鸡(P0.01),雉鸡胸肌与腿肌中粗蛋白的含量极显著的高于AA~+肉鸡(P0.01),雉鸡胸肌与腿肌中粗脂肪的含量极显著地低于AA~+肉鸡(P0.01)。     

地塞米松对AA肉鸡生产性能及红、白细胞数量的影响

为了研究地塞米松(dexamethasone,DEX)对AA肉鸡生长后期增重、料重比及红、白细胞数量的影响,试验将28日龄AA肉鸡20只随机分为试验组和对照组(n=10)。预饲7 d,空腹称重后,试验组和对照组分别按2 mg/kg和2 mL/kg体重剂量胸部肌肉注射DEX和生理盐水,连续注射7 d,每天记录采食量,于42日龄再次空腹称重,计算料重比;颈静脉采血,进行红、白细胞的计数。结果试验组AA肉鸡增重低于对照组,差异显著(P0.05),料重比明显高于对照组,且差异极显著(P0.01);红、白细胞数量分别提高了20.23%、36.32%,与对照组相比,差异极显著(P0.01)。结论为2 mg/kg体重剂量的DEX能降低AA肉鸡生长后期生产性能,影响肉鸡外周血液中红、白细胞的含量。     

黄曲霉毒素B_1诱导的AA肉鸡亚慢性肝损伤模型的建立与评价

72只AA肉鸡适应性饲养3 d后随机分为4组,分别为空白对照组(不含黄曲霉毒素B_1(AFB_1)的空白饲料)、AFB_1低剂量组(饲料中含1 mg/kg AFB_1)、AFB_1中剂量组(饲料中含3 mg/kgAFB_1)、AFB_1高剂量组(饲料中含5 mg/kg AFB_1)。结果表明,连续饲喂高剂量AFB_128 d时,AA肉鸡肝体指数显著高于对照组(P0.05);血清酶学指标谷丙转氨酶(ALT)、谷草转氨酶(AST)活性极显著高于对照组(P0.01),碱性磷酸酶(ALP)活性显著高于对照组(P0.05);肝脏总超氧化物岐化酶(T-SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性极显著低于对照组(P0.01),丙二醛(MDA)含量极显著高于对照组(P0.01)。病理切片结果显示,在28 d AFB_1高剂量组肉鸡肝脏发生严重病变。平均日增重结果表明,在14~21 d,AFB_1中、高剂量组AA肉鸡均极显著低于对照组(P0.01);21~28 d,高剂量组平均日增重极显著低于对照组(P0.01),中剂量组平均日增重显著低于对照组(P0.05)。综上所述,连续饲喂含有5 mg/kg AFB_1的饲料28 d可以成功建立肉鸡亚慢性肝损伤模型,饲料中污染AFB_1能严重影响AA肉鸡增重。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -