复合益生菌配合功能性寡糖在早期断奶犊牛上的应用效果

试验研究功能性寡糖和复合益生菌对早期断奶犊牛生长性能、粪便评分、免疫功能及断奶应激的影响。30头娟西杂犊牛，随机分为2组，对照组犊牛饲喂正常开食料，试验组开食料中添加2 g/（头·d）甘露寡糖、3 g/（头·d）果寡糖及15 g/（头·d）的复合益生菌，试验正式期60 d。试验结果显示，试验组犊牛平均日增重、粗蛋白和粗脂肪的表观消化率显著高于对照组（P<0.05）；试验组血清中IgG含量显著高于对照组（P<0.05），而试验组血清中白细胞介素（IL-1）含量显著低于对照组（P<0.05）。整个试验期，试验组的粪便得分低于对照组。与断奶前2 d相比，断奶后4 d对照组血清中IL-1、血中超敏C蛋白、结合珠蛋白和皮质醇水平显著升高（P<0.05）；断奶后4 d试验组血中超敏C蛋白水平显著升高（P<0.05），但是血中IL-1、结合珠蛋白和皮质醇水平均无显著变化（P>0.05）。研究表明，断奶前期在犊牛开食料中补充复合微生态制剂和功能性寡糖可以提高犊牛的生长的性能，降低粪便评分，增强犊牛的免疫，缓解断奶应激。     

布拉氏酵母菌对哺乳犊牛腹泻率、血清免疫、抗氧化指标及粪便微生物的影响

试验旨在探讨布拉氏酵母对犊牛腹泻率、血清免疫、抗氧化指标及粪便微生物的影响。试验选取了48头新生重(38.16±3.73)kg相近且健康状况良好的中国荷斯坦犊牛,随机分成四组,每组12头且公母对半。各处理组饲粮中分别添加0(对照)、1、3、5 g/(d·头)的布拉氏酵母。试验周期为42 d。结果表明:1～21 d时,3、5 g/(d·头)试验组犊牛的粪便评分显著低于对照组(P0.05),且1、3、5 g/(d·头)试验组犊牛腹泻率比对照组分别降低了35%、52%和42%(P0.05)。试验第21 d,3、5 g/(d·头)试验组犊牛的血清免疫球蛋白A(IgA)、免疫球蛋白M(IgM)、免疫球蛋白G(IgG)、白介素-2(IL-2)和白介素-4(IL-4)含量显著高于对照组(P0.05);对照组犊牛的血清白介素-1β(IL-1β)和肿瘤坏死因子-α(TNF-α)含量显著高于其他各试验组(P0.05);试验第21 d和42 d,3、5 g/(d·头)试验组犊牛的血清丙二醛(MDA)含量显著低于对照组(P0.05)。试验第21 d,3、5 g/(d·头)试验组犊牛粪便的大肠杆菌数量显著低于对照组(P0.05),乳酸菌数量显著高于对照组(P0.05);试验第42 d,3、5 g/(d·头)试验组犊牛粪便的乳酸菌数量显著高于对照组(P0.05)。可见,在犊牛早期(1～21 d)饲粮中补充布拉氏酵母可以通过提高肠道有益菌的数量,抑制肠道致病菌的定植,从而降低犊牛的腹泻率、提高机体的抗氧化能力和免疫力,3 g(1.38×10~(10)CFU/g)布拉氏酵母的添加效果最佳。     

甘露寡糖对犊牛血液免疫球蛋白的研究

选择 30头犊牛 ,随机分成 5组 ,每组 6头。对照组饲喂不含甘露寡糖的牛奶 ,试验 1、2、3、4组分别喂含甘露寡糖 1、2、3、4 g的牛奶 ,通过 30d的试验。结果表明 ,其头平均增重对照组和试验 1、2、3、4组分别为 1 1 .0 2、1 2 .1 2、1 2 .2 5、1 0 .6 2和 1 1 .30kg ,试验 1、2、3、4组增重分别比对照组增加 1 0、1 1 .2、- 3.6和 2 .5 %。试验 1、2、3、4组经济效益分别比对照组提高 1 4 .4、1 3.6 8、-1 5 .4、和 - 7.5 2元。试验结束后对试验 1组和对照组犊牛血液免疫球蛋白IgG、IgA进行测定 ,发现试验 1组比对照组IgA水平提高 2 2 % ,IgG提高 0 .6 % ,研究证明 ,饲喂 1g甘露寡糖效果最好     

哺乳犊牛的饲喂程序对后续繁殖性能和血浆代谢物的影响

文章旨在评估哺乳期犊牛饲喂程序对其后续繁殖性能及各阶段血浆代谢物浓度的影响。试验将体重接近的72头刚出生的犊牛随机分为3组，每组24头。犊牛出生后3?d开始饲喂代乳料（200?g/L），T1和T2组犊牛在第3天每天饲喂3?L代乳料，之后逐渐增加饲喂量，在20?d时达到9?L/d，之后以9?L/d持续到90?d（T1组）和60?d（T2组），T3组犊牛在9～30?d时每天饲喂6?L代乳料，在31～70?d每天饲喂7?L代乳料。结果：T1和T2组90?d肉牛的代乳料摄入量较T3组显著提高14.62%和10.66%（P＜0.05），而T2组300?d肉牛的体高较T1和T3组分别显著提高4.18%和3.75%（P＜0.05）。T3组母牛的第一次授精时间显著高于T1和T2组（P＜0.05），而T2和T3组母牛11～13月龄妊娠率及1次人工授精受孕率显著高于T1组（P＜0.05）。T3组60?d牛血浆葡萄糖、磷浓度及180?d IGF-1浓度均显著高于T1组（P＜0.05）。在60?d时，T2和T3组血浆胆固醇和钙浓度显著高于T1组（P＜0.05），T1和T2组血浆非酯化脂肪酸浓度显著高于T3组（P＜0.05）。结论：在本试验条件下，断奶后3?d的犊牛以最高7?L/d饲喂代乳料是最合适的饲喂程序，而以最高9?L/d饲喂代乳料会降低人工授精时母牛的受孕率。 [关键词]犊牛|饲喂程序|繁殖性能|代谢物     

葛根多糖对犊牛血清抗氧化、免疫指标及肠道菌群的影响

本试验旨在研究葛根多糖对犊牛血清抗氧化、免疫指标及肠道菌群的影响。试验选取（6.20±3.65）日龄和体重[（47.09±4.50） kg]相近的新生健康荷斯坦犊牛24头，随机分为对照组（C组）和试验组（T组），每组12头。T组犊牛每头每天按每千克体重于牛奶中添加400 mg葛根多糖，连续5 d;C组不添加。检测试验犊牛第7天血清抗氧化指标——超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、一氧化氮合酶（NOS）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量，免疫指标——CD4分子（CD4）、免疫球蛋白A(IgA)、分泌型免疫球蛋白A(sIgA)、免疫球蛋白G(IgG)含量和肠道黏膜通透性指标——二胺氧化酶（DAO）活性以及肠道菌群多样性和相对丰度。结果显示：1）与C组相比，T组犊牛血清SOD、CAT、NOS和GSH-Px活性分别提高了10.16%、1.79%、7.05%和3.43%(P>0.05)，血清MDA含量降低了2.27%(P>0.05)。2）与C组相比，T组犊牛血清DAO活性降低了2.38%(P>0.05)，血清CD4、sIgA、IgA和Ig...     

枸杞多糖对犊牛生长性能、消化水平、免疫功能及抗氧化能力的影响

试验旨在研究枸杞多糖(LBP)对荷斯坦母犊生长性能、消化水平、免疫及抗氧化性能的影响。选取体重(70±5) kg、日龄(50±5) d的48头荷斯坦母犊,随机分为4组,每组12个重复,每个重复1头牛。对照组犊牛饲喂开食料和代乳粉,试验1组、试验2组、试验3组分别在代乳粉中添加5、10、15 g/(头·d) LBP。预试期7 d,正式试验期60d。结果显示,与CON组相比,饲喂10 g/(头·d)LBP可以显著提高犊牛体重及平均日增重(P<0.05);5 g/(头·d)LBP可以提高犊牛对日粮中粗蛋白(CP)、粗脂肪(EE)、钙(Ca)、磷(P)的消化水平(P<0.05);10、15 g/(头·d)LBP可以提高犊牛血清中免疫球蛋白A (IgA)、白细胞介素-6 (IL-6)水平(P<0.05);10、15 g/(头·d)LBP可以提高犊牛血清中超氧化物歧化酶(SOD)活性,降低丙二醛(MDA)、活性氧(ROS)含量(P<0.05)。研究表明,饲喂LBP可以通过提高犊牛消化率、免疫功能、抗氧化能力达到提高生长性能的目的,且饲喂10 g/(头·d) LBP时效果较好...     

山药多糖对犊牛免疫功能、抗氧化能力及肠道菌群的影响

试验旨在探讨山药多糖对犊牛免疫功能、抗氧化能力及肠道菌群的影响。选择36头（30±3） d、体重（55.27±1.53） kg的健康荷斯坦犊牛,随机分为2组,每组18个重复,每个重复1头牛。对照组（CG组）饲喂代乳粉5 L/(头·d),试验组（EG组）饲喂含10 g山药多糖的代乳粉5 L/(头·d)。试验期10 d。结果显示,与CG组相比,EG组犊牛血清免疫球蛋白A (IgA)、免疫球蛋白G (IgG)、免疫球蛋白M (IgM)、肿瘤坏死因子-α(TNF-α)含量及超氧化物歧化酶（SOD）活性显著升高（P<0.05）。EG组犊牛肠道菌群OTUs增多,有益菌厚壁菌门（Firmicutes）、变形菌门（Proteobacteria）、放线菌门（Actinobacteriota）的相对丰度分别提高了21.67%、60.83%、88.25%,有害菌梭杆菌门相对丰度减少。研究表明,在犊牛代乳粉中添加山药多糖可增强犊牛免疫功能,提高抗氧化能力,能够通过增加肠道有益菌数量,减少有害菌数量,调节肠道菌群结构。     

大豆黄酮对荷斯坦牛围产期某些代谢激素的影响

12头的初胎荷斯坦乳牛,分为对照期(添喂前)和试验期(添喂后)。于预产期前10d一次添喂大豆黄酮(80mg/d·头),在添喂前、添喂后的7d、产后3d、10d和17d采取血样,用放射免疫法测定血浆中TSH、T3、T4和胰岛素的含量。①添喂大豆黄酮后,T3的水平在第7d、产后3d和产后10d显著低于对照期(P<0.05/P<0.01),而产后17dT3含量则高于对照期21.60%(P<0.05);②试验期中T4的水平除分娩后第10d外,均显著低于对照期(P<0.05/P<0.01);③TSH水平仅在添喂大豆黄酮后的第7d显著低于对照期,而分娩后与对照期差异不显著(P>0.05);④胰岛素在大豆黄酮处理后的第7d和分娩后的第17d显著低于对照期,其余与对照无显著差异(P>0.05)。以上结果提示:大豆黄酮能影响分娩后初胎奶牛的代谢激素水平,促进营养物质的转化,加强机体蛋白质的合成,以适应机体泌乳的生理变化。     

大豆黄酮对奶牛泌乳及相关激素的影响

为了研究大豆黄酮对奶牛泌乳性能的影响及其可能的作用机制,选用14头产奶水平相近的泌乳后期奶牛,随机分为对照组、试验组。试验组日粮添加10ppm的大豆黄酮,持续30天。结果发现：大豆黄酮能缓解泌乳后期奶牛产奶量下降的趋势,并在一定程度上提高产奶量。与对照组相比,乳蛋白有所升高,乳脂率有所下降。试验第30天血浆中GH（P〈0.05）和PRL（P〈0.01）的含量显著升高,E2、T3和T4的含量均有升高的趋势。提示大豆黄酮可能通过调节内源性激素水平而间接地影响奶牛泌乳量和乳成分。     

不同营养调控剂对荷斯坦公牛增重效果的影响

选取42头体重相近的荷斯坦公牛，随机分为7组，每组6头。对照组饲喂基础日粮，调控剂A1、A2、A3组在基础日粮中添加营养调控剂A，添加剂量分别为2g／（d·头）、5g／（d·头）和8g／（d·头）。调控剂B1、B2、B3组在基础日粮中添加营养调控剂B，添加剂量分别为2g／（d·头）、5g／（d·头）和8g／（d·头）。试验结果表明，调控剂A2组和调控剂B2组的平均日增重与对照组相比，分别增加了0．19kg和0．20kg，差异显著（P〈0．05）；以上两组的平均日收入与对照组相比，分别增加了3．57元和3．82元。结果表明，营养调控剂A和营养调控#IB在荷斯坦公牛日粮中添加剂量为5g／（d·头）时，可以促进公牛的增重，提高经济效益。     

Phenotypic comparison of ileal intraepithelial lymphocyte populations of suckling and weaned calves

Ileal intraepithelial lymphocyte (IEL) suspensions from suckling calves (1-3 weeks old) and weaned calves (3-6 months old) were phenotyped to determine whether there were differences in the lymphocyte populations consistent with postnatal maturation of the mucosal immune system. Flow cytometric comparisons of IEL from the two age groups revealed the presence of significantly larger proportions of CD4+ T lymphocytes and CD8+ T cells in the weaned animals. In contrast, there was a significantly larger proportion of B-B2+ IEL in the suckling calves. Freshly isolated IEL from both groups of calves expressed mRNA for TNF-alpha and IFN-gamma, but not IL-4 or IL-10. The B-B2+ IEL population was more closely examined by flow cytometry. These cells co-expressed IgM and CD21. However, they did not express IgA, IgG1, nor any of several additional leukocyte differentiation molecules. Immunohistochemical data confirmed the presence of IgM+ lymphocytes, and the paucity of IgA+ and IgG1+ lymphocytes in suckling calf ileum. However, substantial numbers of IgA+ and IgG1+ cells were observed in weaned calf ileum. Together, the data are consistent with ongoing postnatal maturation of the gut mucosal immune system.     

Effects of natural zeolite clinoptilolite on passive immunity and diarrhea in newborn Holstein calves

In the present study, the effects of natural zeolite clinoptilolite on absorption of immunoglobulins from colostrum and incidence of enteric diseases were evaluated. In a completely randomised design, thirty Holstein calves were fed pooled colostrum and then milk containing zero (control), 0.5 (T1), 1.0 (T2), 1.5 (T3) and 2.0 (T4) g clinoptilolite per kg body weight per day through day 45. Blood was collected after birth and at 24 h of age and plasma IgG and IgM concentrations were determined. Fecal consistency score and severity of diarrhea were recorded for each calf twice daily. Calves receiving T3 and T4 had lower (P < 0.05) plasma IgG concentration than control and other treatments. Calves on T2 had higher (P < 0.05) plasma IgG concentration than T3 and T4, but not T1 and control. Inclusion of clinoptilolite to colostrum did not affect (P > 0.05) IgM absorption from the intestine of newborn calves. Fecal consistency scores were lower (P < 0.05) for calves on T1 and T2 and higher for calves on T3 and T4 than calves on control. Percent calf days with diarrhea followed the same trend. In overall, seven calves died, those being one each on control and T1, two on T3 and three on T4. Based upon these results, addition of 1.0 g clinoptilolite per kg body weight per day to colostrum and milk could reduce diarrhea, but its effect on passive immunity was negligible. Over 1.0 g/kg body weight per day, clinoptilolite had adverse effect on passive immunity and diarrhea.     

Humoral immune response of the bovine fetus to in utero vaccination with attenuated bovine coronavirus

A fetal response to in utero vaccination with attenuated bovine coronavirus (9 to 49 days before parturition) was determined in 8 calves, 5 vaccinated and 3 controls. Calves were derived by hysterotomy before parturition and were maintained in a closed gnotobiotic environment. The IgA, IgM, and IgG values and coronavirus-neutralizing antibody titers were higher in the sera and intestinal loop fluid from vaccinated calves than in those from control calves. Sections of ileum and ileal lymph nodes from 1-day-old vaccinated calves, when stained with monospecific anti-bovine IgG, IgM, and IgA had numerous positively stained plasma cells. Positive fluorescence was not detected in comparable tissues from controls. When the 8 calves were given virulent coronavirus orally at 6 days of age, vaccinated calves did not become ill, whereas control calves had diarrhea in 19 to 22 hours. All calves were killed at 10 days of age. Control calves had lesions characteristic of coronavirus infection, and intestinal epithelial cells were positive by fluorescent antibody tests. In vaccinated calves, lesions of coronavirus infection were absent, and results of fluorescent antibody tests were negative. Although in utero vaccination with a coronavirus vaccine stimulated immunity in the newborn calf, the frequency of abortions (2 of 14 cows inoculated intra-amniotically) and premature births (4 of 14) precluded practical application.     

Modulation by colostrum-acquired maternal antibodies of systemic and mucosal antibody responses to rotavirus in calves experimentally challenged with bovine rotavirus

The effect of colostral maternal antibodies (Abs), acquired via colostrum, on passive protection and development of systemic and mucosal immune responses against rotavirus was evaluated in neonatal calves. Colostrum-deprived (CD) calves, or calves receiving one dose of pooled control colostrum (CC) or immune colostrum (IC), containing an IgG1 titer to bovine rotavirus (BRV) of 1:16,384 or 1:262,144, respectively, were orally inoculated with 105.5 FFU of IND (P[5]G6) BRV at 2 days of age. Calves were monitored daily for diarrhea, virus shedding and anti-BRV Abs in feces by ELISA. Anti-rotavirus Ab titers in serum were evaluated weekly by isotype-specific ELISA and virus neutralization (VN). At 21 days post-inoculation (dpi), all animals were euthanized and the number of anti-BRV antibody secreting cells (ASC) in intestinal and systemic lymphoid tissues were evaluated by ELISPOT. After colostrum intake, IC calves had significantly higher IgG1 serum titers (GMT=28,526) than CC (GMT=1195) or CD calves (GMT<4). After BRV inoculation, all animals became infected with a mean duration of virus shedding between 6 and 10 days. However, IC calves had significantly fewer days of diarrhea (0.8 days) compared to CD and CC calves (11 and 7 days, respectively). In both groups receiving colostrum there was a delay in the onset of diarrhea and virus shedding associated with IgG1 in feces. In serum and feces, CD and CC calves had peak anti-BRV IgM titers at 7 dpi, but IgA and IgG1 responses were significantly lower in CC calves. Antibody titers detected in serum and feces were associated with circulation of ASC of the same isotype in blood. The IC calves had only an IgM response in feces. At 21 dpi, anti-BRV ASC responses were observed in all analyzed tissues of the three groups, except bone marrow. The intestine was the main site of ASC response against BRV and highest IgA ASC numbers. There was an inverse relationship between passive IgG1 titers and magnitude of ASC responses, with fewer IgG1 ASC in CC calves and significantly lower ASC numbers of all isotypes in IC calves. Thus, passive anti-BRV IgG1 negatively affects active immune responses in a dose-dependent manner. In ileal Peyer's patches, IgM ASC predominated in calves receiving colostrum; IgG1 ASC predominated in CD calves. The presence in IC calves of IgG1 in feces in the absence of an IgG1 ASC response is consistent with the transfer of serum IgG1 back into the gut contributing to the protection of the intestinal mucosa.     

复方女贞子和益生菌对新生奶犊牛增重及免疫功能的影响

用复方女贞子（由女贞子、黄芪、党参组成）和益生菌对新生奶犊牛进行了增重和免疫功能影响实验。实验选用奶犊牛20头,随机分为4组,每组5头,用药30 d,共饲养120 d,测定其对犊牛增重和血清免疫球蛋白的影响。结果显示,中药组和中药益生菌联合组的犊牛平均日增重明显提高（P〈0.01）,犊牛血清中IgG、IgA、IgM含量显著升高（P〈0.01）。表明复方女贞子单用或与益生菌联合使用可促进犊牛生长,明显提高犊牛的免疫功能。     

Isotype- and subclass-specific responses to infection and reinfection with parainfluenza-3 virus: comparison of the diagnostic potential of ELISAs detecting seroconversion and specific IgM and IgA.

Isotype- and subclass-specific indirect enzyme-linked immunosorbent assays were developed to detect parainfluenza-3 virus-specific IgG1, IgG2, IgM, and IgA responses. Sera were treated with protein G-agarose prior to testing for specific IgM and IgA to eliminate the possibility of false-positive results due to IgM-rheumatoid factor and to remove interisotypic competition due to specific IgG. IgM and IgA absorbance values were expressed as a percentage of the absorbance values of positive reference sera included on each plate (S/P%), and respective positive/negative threshold values of 15.0% and 28.0% were determined. The mean interval between experimental infection of 3 calves and initial detection of specific IgG1 and IgG2 responses was 8.0 and 9.3 days respectively, rising rapidly to an initial plateau 13.7 and 11.0 days postinfection (dpi). Reinfection of these calves at 30 dpi resulted in further rapid increases, with higher plateau values reached 13.0 (IgG1) and 13.7 (IgG2) days later. The mean interval between infection and the first positive IgM and IgA responses was 6.7 and 12.3 days, respectively. IgM S/P% values peaked at 13.0 dpi, with all 3 calves showing a secondary anamnestic response to reinfection, peaking 4.7 days later. The IgA response to initial infection was weak, with only 2 calves showing an obvious peak response at 15.0 dpi. A strong anamnestic IgA response to reinfection occurred in 2 calves, with a peak response 9.5 days later. Apparent biphasic and triphasic IgM and IgA responses were evident in some calves. Acute and convalescent serum samples from 80 calves involved in 17 outbreaks of respiratory disease were tested for specific IgM and IgA. Positive IgM results were detected in 15 outbreaks, with 71 sera from 44 calves testing positive. Although IgA-positive results were detected in the same 15 outbreaks, only 42 sera from 31 calves were positive. In a previous study, seroconversion was detected in 21 of these calves from 10 outbreaks. Thus the diagnostic potential of the assays was in the order IgM > IgA > seroconversion. The correlations between IgM and IgA, IgM and seroconversion, and IgA and seroconversion results for each calf were 73.8%, 58.8% and 62.5%, respectively.     

Intestinal antibody response after vaccination and infection with rotavirus of calves fed colostrum with or without rotavirus antibody

The intestinal and systemic antibody response of calves vaccinated and/or challenged with rotavirus was studied employing isotype-specific ELISAs for the detection of IgG1, IgG2, IgM and IgA antibodies to rotavirus. Monoclonal antibodies to bovine immunoglobulin isotypes of proven specificity were used as conjugated or catching antibody. Five days after oral inoculation (dpi) of a 5-day-old gnotobiotic calf with rotavirus, IgM rotavirus antibodies were excreted in faeces, followed 5 days later by IgA rotavirus antibodies. The increase in IgM rotavirus antibody titre coincided with the inability to detect further rotavirus excretion. Faeces IgM and IgA rotavirus antibody titres fell to low levels within 3 weeks post infection. IgG1 and IgG2 rotavirus antibodies were not detected in faecal samples. In serum, antibodies to rotavirus of all four isotypes were detected, starting with IgM at 5 dpi. Two SPF-calves, which were fed colostrum free of rotavirus antibodies, were vaccinated with a modified live rotavirus vaccine and challenged with virulent rotavirus 6 days later. Upon vaccination, the calves showed an antibody response similar to the response of the infected gnotobiotic calf. Intestinal IgM rotavirus antibodies were excreted before or on the day of challenge and appeared to be associated with protection against challenge infection with virulent virus and rotavirus-induced diarrhoea. In 3 control calves, which were challenged only, the antibody patterns also resembled that of the gnotobiotic calf and again the appearance of IgM rotavirus antibodies coincided with the end of the rotavirus detection period. Two other groups of 3 SPF-calves were treated similarly, but the calves were fed colostrum with rotavirus antibodies during the first 48 h of life. These calves excreted passively acquired IgG1 and IgG2 rotavirus antibodies in their faeces from 2 to 6 days after birth. After vaccination, no IgM or IgA antibody activity in serum or faeces was detectable. Upon challenge, all calves developed diarrhoea and excreted rotavirus. Seven to 10 days after challenge low levels of IgM rotavirus antibody were detected for a short period. These data indicate that the intestinal antibody response of young calves to an enteric viral infection is associated with the excretion of IgM antibodies, immediately followed by IgA antibodies. This response is absent or diminished in calves with passively acquired specific antibodies which may explain the failure to induce a protective intestinal immune response by oral vaccination with modified live rotavirus of calves fed colostrum containing rotavirus antibodies.     

白头翁皂苷B4对哺乳期犊牛生长性能和血清指标的影响

本试验旨在研究白头翁皂苷B4对哺乳期犊牛生长性能和血清指标的影响.选取60头新生荷斯坦公犊牛,随机分为4组(每组15头),分别饲喂在代乳粉中添加0(C组)、15(A1组)、30(A2组)和45 mg/d(A3组)白头翁皂苷B4的饲粮.试验期56 d,其中预试期14 d,正试期42 d.每2周空腹称重、测量体尺,每日记录...     

Chronic pneumonia in calves after experimental infection with Mycoplasma bovis strain 1067: Characterization of lung pathology,persistence of variable surface protein antigens and local immune response

Background

Mycoplasma bovis is associated with pneumonia in calves characterized by the development of chronic caseonecrotic lesions with the agent persisting within the lesion. The purposes of this study were to characterize the morphology of lung lesions, examine the presence of M. bovis variable surface protein (Vsp) antigens and study the local immune responses in calves after infection with M. bovis strain 1067.

Methods

Lung tissue samples from eight calves euthanased three weeks after experimental infection with M. bovis were examined by bacteriology and pathology. Lung lesions were evaluated by immunohistochemical (IHC) staining for wide spectrum cytokeratin and for M. bovis Vsp antigens and pMB67 antigen. IHC identification and quantitative evaluation of CD4⁺ and CD8⁺ T lymphocytes and immunoglobulin (IgG1, IgG2, IgM, IgA)-containing plasma cells was performed. Additionally, expression of major histocompatibility complex class II (MHC class II) was studied by IHC.

Results

Suppurative pneumonic lesions were found in all calves. In two calves with caseonecrotic pneumonia, necrotic foci were surrounded by epithelial cells resembling bronchial or bronchiolar epithelium. In all calves, M. bovis Vsp antigens were constantly present in the cytoplasm of macrophages and were also present extracellularly at the periphery of necrotic foci. There was a considerable increase in numbers of IgG1- and IgG2-positive plasma cells among which IgG1-containing plasma cells clearly predominated. Statistical evaluation of the numbers of CD4⁺ and CD8⁺ T cells, however, did not reveal statistically significant differences between inoculated and control calves. In M. bovis infected calves, hyperplasia of bronchus-associated lymphoid tissue (BALT) was characterized by strong MHC class II expression of lymphoid cells, but only few of the macrophages demarcating the caseonecrotic foci were positive for MHC class II.

Conclusions

The results from this study show that infection of calves with M. bovis results in various lung lesions including caseonecrotic pneumonia originating from bronchioli and bronchi. There is long-term persistence of M. bovis as demonstrated by bacteriology and immunohistochemistry for M. bovis antigens, i.e. Vsp antigens and pMB67. The persistence of the pathogen and its ability to evade the specific immune response may in part result from local downregulation of antigen presenting mechanisms and an ineffective humoral immune response with prevalence of IgG1 antibodies that, compared to IgG2 antibodies, are poor opsonins.     

热应激牛初乳对新生犊牛血清免疫指标的影响研究

新生犊牛通过初乳获得被动免疫,但是关于热应激对新生犊牛被动免疫的影响程度尚不清楚。本试验旨在研究热应激牛初乳对新生犊牛被动免疫是否有显著影响,并与非热应激生产条件下进行比较。试验动物为对应于采食热应激和非热应激母牛初乳的新生犊牛各4头,在其采食母牛初乳后的不同时间内采血用于免疫指标分析。结果表明:热应激奶牛哺乳犊牛血清中各成分含量在144h内均低于非热应激奶牛哺乳犊牛血清中相对应成分,其中IgG、T3、T(472h内)变化差异显著(P<0.05),INS和IGF-Ⅰ变化差异不显著(P>0.05),热应激在一定程度上影响新生犊牛被动免疫,有关机理有待于进一步研究。