微生物菌剂对牛粪堆肥中酶活性的影响

【目的】明确牛粪堆肥接种菌剂后在高温好氧堆肥过程中几种酶活性的动态变化,通过酶学角度揭示高温好氧堆肥的生物化学机理,为堆肥腐熟综合评价指标体系及腐熟阈值的制定提供科学依据.【方法】以牛粪为堆肥原料,通过接种两种微生物菌剂处理,分析高温堆肥堆体温度与酶活性的变化特征.【结果】接种菌剂有效地增加了堆肥温度,延长了高温期,且使脲酶、纤维素酶、蛋白酶活性水平与峰值得到明显提高.堆肥过程中过氧化氢酶与脲酶活性变化基本一致,后期高于前中期.多酚氧化酶活性呈不断下降并逐步稳定的趋势.堆肥前期纤维素酶出现峰值,不接种菌剂的处理(CK)蛋白酶活性中后期稳定升高.【结论】接种菌剂纤维素酶活性与堆肥温度呈极显著负相关性(P0.01);多酚氧化酶两者则呈显著正相关性(P0.05).接种菌剂2对过氧化氢酶、脲酶活性与堆体温度于不同阶段表现出显著(或极显著)相关性.CK的蛋白酶活性与堆体温度有极显著负相关性(P0.01),表明酶活性大小可作为牛粪堆肥过程中腐熟程度的生化评定指标.     

Effect of Different Roughages on Milk Protein and Milk Fat Synthesis in Dairy Cows

The main purpose of this study was to determine the effect of a corn straw or mixed diet on milk production, milk composition and the expression of genes associated with lactation in mid-lactation Chinese Holstein cows. In this study, 10 healthy Chinese Holstein cows were randomly assigned to two groups and fed with different diets respectively, corn straw(CS) or mixed forage(MF) diet. CS group was fed roughage consisting of 53.8% corn straw only and the forge to concentrate(F : C) ratio [dry matter(DM)] was about 40: 60. MF group was fed roughage consisting of 3.7% Chinese wildrye and 23.4% alfalfa hay, the forge to concentrate(F : C) ratio(DM) was 70: 30. All the cows were fed 8 weeks and body weight, dry matter intake, body condition score, fat, protein, lactose, milk yield, total solid and somatic cell count(SCC) were recorded. Quantitative real-time PCR(q RT-PCR) was used to analyze cow mammary gland samples representing two different diets. The results suggested that different diet types had significant effects on milk yield, lactose, milk fat, milk protein, dry matter intake and somatic cell count in dairy cows, and cows fed MF diet improved milk production and lactation performance clearly(P0.05). In addition, m RNA expression of genes ACC, m TOR, STAT5, CSN2, PPARγ, FABP3 and PTEN in MF group was extremely significantly higher than that in CS group(P0.05). m RNA expression of AKT1, FAS, SCD and SREBP1 c in MF group was significantly higher than that in CS group(P0.01). In summary, the milk yield and composition in mixed forage group were significantly improved than those in corn straw group.     

低温环境下水稻秸秆与牛粪混合堆肥效果研究

[目的]实现低温季节水稻秸秆和牛粪的资源化利用。[方法]以25%水稻秸秆+75%牛粪作为对照(CK),设置25%水稻秸秆+75%牛粪+5‰低温发酵剂、35%水稻秸秆+65%牛粪+5‰低温发酵剂2个处理,分别进行堆肥,研究低温发酵剂及不同水稻秸秆用量对堆肥效果的影响。[结果]25%水稻秸秆+75%牛粪+5‰低温发酵剂、35%水稻秸秆+65%牛粪+5‰低温发酵剂处理的高温期持续7和8 d,高温持续时间长。CK堆温始终未进入高温期。堆肥结束时,25%水稻秸秆+75%牛粪+5‰低温发酵剂、35%水稻秸秆+65%牛粪+5‰低温发酵剂处理和CK的有机质含量分别较初始降低了31.72、30.54和14.10个百分点,粗纤维降低了32.44、33.09和15.00个百分点。经方差分析,水稻秸秆用量为25%~35%时,有机质及粗纤维降解率差异不显著,而对照与2个处理间差异达到极显著水平(P0.01)。[结论]低温发酵剂可促使堆体升温,加快有机质及粗纤维的降解。     

奶牛蹄病与矿物元素相关性研究

[目的]探究奶牛体内矿物元素含量与蹄病的关系。[方法]从某大型集约化奶牛场随机抽取8头患蹄病的奶牛和8头健康奶牛,采用原子吸收分光光度法检测患蹄病奶牛与健康奶牛血清中一些矿物元素(K、Fe、Cu、Mg、Mn、Na、Zn、Ca)的含量,分析了矿物元素的代谢与奶牛蹄病之间的关系。[结果]与对照组相比,试验组奶牛血清中Zn和Mn含量差异极显著(P0.01),试验组Ca和Mg含量差异显著(P0.05),试验组K、Fe、Cu和Na含量差异不显著(P0.05)。[结论]患蹄病奶牛内矿物元素代谢异常,特别是与骨骼生长发育有关的元素代谢紊乱,容易导致蹄病的发生。     

不同营养水平对淘汰荷斯坦奶牛消化代谢、肉品质的影响

为了研究不同能量蛋白水平对淘汰荷斯坦奶牛消化代谢、肉品质的影响。采用单因素随机设计,选择体重相近的健康淘汰荷斯坦奶牛32头,随机分成4组,Ⅰ组(低营养水平)、Ⅱ(中营养水平)、Ⅲ(较高营养水平)、Ⅳ(高营养水平),试验分两期进行。结果表明,随着日粮营养水平的增加,各试验组粗蛋白、粗脂肪表观消化率差异显著(P<0.05),其中Ⅲ组最高,分别达到72.47%和80.64%;Ⅳ组背膘厚度比Ⅰ组提高了73.33%(P<0.05)。日粮营养水平能显著影响熟肉率、肉中脂肪和脂肪酸含量。其中,Ⅲ组熟肉率最高,为49.73%,比Ⅰ组、Ⅱ组、Ⅳ组分别提高6.03%,7.87%和4.30%(P<0.01);牛肉中脂肪含量Ⅰ组最低,为4.08%,Ⅳ组最高,达到6.94%;各试验组牛肉中多不饱和脂肪酸(PUFA)差异显著(P<0.05),Ⅳ组PUFA含量最低,为3.67%,Ⅱ组最高,达到5.93%,Ⅱ组比Ⅳ组提高61.58%(P<0.05),Ⅲ组PUFA含量比Ⅰ组、Ⅳ组分别高2.47%和58.31%(P<0.05)。因此,淘汰荷斯坦奶牛育肥营养水平建议值为:体重410~470 kg,干物质采食量为11.03~11.53 kg/d,DE摄入量为147.86~150.05 MJ/d,CP摄入量为1.57~1.66 kg/d(DM);育肥牛体重470~530 kg,干物质采食量为10.76~11.23 kg/d,DE摄入量为149.18~151.21 MJ/d,CP摄入量为1.53~1.62 kg/d(DM)。     

荷斯坦牛乳源金黄色葡萄球菌流行性及其与乳源总菌群的耐药性分析

本研究旨在检测并对比分析中国北方地区3个荷斯坦牛场乳源金黄色葡萄球菌(Staphylococcus aureus,简称金葡菌)的流行情况及乳汁中总菌群的抗生素耐药性。试验采集北方地区3个荷斯坦牛场的生产群奶样、大罐奶样和临床型乳房炎牛奶样共181份,首先采用Baird-Parker选择性培养基对金葡菌进行分离纯化;再采用特异性PCR方法鉴定含金葡菌特异基因nuc的金葡菌菌株;最后采用琼脂稀释法检测奶样中总菌群及金葡菌对14种抗生素的耐药性。结果发现,181份奶样带菌率为100%;金黄色葡萄球菌检出率为16.03%,分离纯化了48株金葡菌。奶样总菌群耐药性检测结果表明,中国北方地区3个荷斯坦牛场对于β-内酰胺类抗生素(苯唑西林、氨苄西林、头孢西丁、头孢哌酮)耐药性均较高,达89%以上;对红霉素、利福平、四环素、万古霉素、甲氧苄啶/磺胺甲噁唑、阿莫西林/克拉维酸的耐药性达80%以上;对氯霉素的耐药率过半;仅对阿米卡星耐药率较低(18%~58%)。对金葡菌耐药性检测结果显示,3个牛场金葡菌对环丙沙星、头孢西丁和甲氧苄啶/磺胺甲噁唑有较高耐药性,但均对阿米卡星、氯霉素、加替沙星和万古霉素敏感。3个牛场绝大多数菌株都产生了多重耐药谱。研究结果为奶牛场乳源总菌群、金葡菌耐药性情况及科学用药提供试验数据。     

自然生产条件下热应激周期变化揭示泌乳中期奶牛出现“热应激乳蛋白降低征”

本试验在连续3年时间里测定了上海地区热应激周期变化对泌乳中期奶牛生产性能和牛奶品质的影响。通过实地测定并计算分析,绘制了上海地区热应激周期变化图谱,揭示了整个热应激周期中不同热应激程度的分布状况。研究对比了自然生产环境下无热应激与中度热应激对奶牛生产性能和牛奶品质的影响,发现中度热应激极显著降低了奶牛采食量、产奶量、乳脂校正乳产量、能量校正乳产量、乳脂率、乳蛋白含量、总固体含量(P<0.01),而且显著增加了乳中尿素氮含量(P<0.05)。在热应激周期变化研究中发现,中度热应激显著升高泌乳奶牛的直肠温度和呼吸频率(P<0.05),而且呼吸频率比直肠温度对热应激变化的反应更快、更敏感。热应激周期变化对奶牛干物质采食量、产奶量的影响取决于热应激程度,2012年整个热应激周期的热应激程度比较低,热应激周期变化对奶牛干物质采食量、产奶量无显著影响(P>0.05),但是2013年热应激程度更加严重,热应激周期变化对奶牛干物质采食量、产奶量产生了极显著影响(P<0.01)。在牛奶品质中,受热应激影响最大的是乳蛋白合成量(P<0.01)。2012年和2013年2个热应激周期变化对其他乳成分含量没有显著影响(P>0.05),但是两年的热应激周期变化都导致乳蛋白含量显著下降(P<0.05)和乳中尿素氮含量显著升高(P<0.05)。尤其值得注意的是,2012年热应激周期变化并没有导致奶牛采食量下降(P>0.05),而且产奶量也没有显著性差异(P>0.05),但是仍然出现了乳蛋白含量下降和乳中尿素氮含量升高(P<0.05)。这表明热应激周期变化改变了泌乳中期奶牛氮代谢的途径,发生了氮营养重分配(repartitioning)现象,而且这种现象不依赖于采食量和产奶量,可以称之为“热应激乳蛋白降低征”(heat-stressed milk protein decrease syndrome,HS-MPD)。     

奶牛源化脓隐秘杆菌的分离鉴定及其毒力基因的检测

本研究旨在分离鉴定来自北京某奶牛场死亡奶牛肺脏的1株疑似病原菌CVCC 3982,并测定其致病性。通过分离培养获得疑似病原菌,采用Biolog鉴定系统和16S rDNA序列分析对其进行了鉴定,人工接种CD-1小鼠测定了其致病性,合成引物对其主要毒力基因进行了检测。结果显示,该疑似病原菌为革兰氏阳性杆菌,β溶血,Biolog鉴定结果显示其为化脓隐秘杆菌,其16S rDNA序列与化脓隐秘杆菌模式菌株NCTC 5224的同源性达100%,系统发育分析显示其与化脓隐秘杆菌处于同一分支。腹腔注射该菌可致小鼠死亡。分离菌株基因组中含有溶血素(PLO)基因,神经氨酸酶H(NanH)基因,神经氨酸酶P(NanP)基因,菌毛基因(fimA、fimC和fimE),但缺失胶原结合蛋白(CbpA)基因和菌毛fimG基因。结果表明该分离菌株为化脓隐秘杆菌且具有致病性。     

阿米卡星与替米考星对奶牛乳房炎常见病原菌的联合药敏试验

研究了阿米卡星和替米考星2种药物在无乳链球菌、停乳链球菌、金黄色葡萄球菌、致病性大肠埃希菌4种奶牛乳房炎常见病原菌联合药敏试验中的相互作用,结果表明,阿米卡星与替米考星对各菌的MIC均在7.81~62.50μg/ml之间;二者联合后的FIC指数范围0.75~1.0;二者联合用药时为相加作用。     

Influence of a marine algae supplementation on the oxidative status of plasma in dairy cows during the periparturient period

This study was part of a larger study that addressed the effects of marine algae (ALG) supplementation in the ration of high yielding periparturient dairy cows. The objectives were to induce milk fat depression (MFD) in early lactation by feeding docosahexaenoic acid (DHA) from ALG and to determine the effects on milk production, milk components and metabolic status early post partum. This study focuses on the oxidative status in the plasma during the ALG supplementation. Plasma samples were collected from 16 Holstein Friesian cows at the day of parturition and at −1, 2, 4 and 6 weeks relative to calving with half of the cows receiving the ALG supplement (44 g DHA/d) from 3 weeks pre partum on. The following parameters were measured in plasma: ferric reducing ability of plasma (FRAP), α-tocopherol level, glutathione peroxidase activity (GSH-Px) and thiobarbituric acid reactive substances (TBARS) concentration. There was a significant effect of time for FRAP and α-tocopherol indicating changes in the plasma oxidative status around parturition. The ALG supplementation was successful in creating a milk fat depression (MFD) but could not improve the energy balance. Feeding of ALG significantly increased lipid peroxidation as measured by TBARS, probably through their high content of n-3 polyunsaturated fatty acids.