几种脲酶抑制剂对大豆脲酶和绵羊瘤胃微生物脲酶的抑制作用

本文研究了脲酶抑制剂乙酰氧肟酸 (AHA)、邻苯二酚、氢醌 (HQ)和硼砂对大豆脲酶和绵羊瘤胃微生物脲酶的抑制作用。结果表明 ,在浓度为 0 .0 0 0 1,0 .0 0 1,0 .0 1和 0 .1mmol/L时 ,4种脲酶抑制剂对大豆脲酶的抑制率分别为 :AHA为 6 % ,6 .2 % ,9.6 6 %和 2 9.79% ;HQ为 8.4 % ,13.0 3% ,19.79%和 4 4 .75 % ;邻苯二酚为 2 0 .34% ,19.12 % ,83.16 %和 93.78% ;而硼砂为 16 .5 5 % ,17.18% ,18.95 %和 35 .5 0 %。在相同浓度下 ,4种脲酶抑制剂对绵羊瘤胃微生物脲酶的抑制率分别为 :AHA为 9.5 8% ,14 .0 4 % ,4 1.30 %和 72 .73% ;HQ为 12 .2 1% ,39.99% ,6 4 .6 2 %和 78.87% ;邻苯二酚为 6 .0 7% ,9.36 % ,31.2 9%和 5 0 .4 4 % ;而硼砂分别为 4 .97% ,8.6 3% ,2 1.78%和 32 .0 2 %。     

添喂淀粉对饲喂玉米秸秆绵羊瘤胃消化代谢的影响

将5只2.5岁龄装置了永久性瘤胃瘘管和十二指肠瘘管的新疆美利奴羯羊,采用5×5拉丁方设计,分别按0、2、4、6或8 g/d.kg体重添喂纯玉米淀粉,以研究添喂淀粉对饲喂玉米秸秆绵羊瘤胃消化代谢的影响。结果表明,给饲喂玉米秸秆为主的绵羊添喂淀粉,可使瘤胃液氨态氮浓度降低、挥发性脂肪酸浓度升高。玉米秸秆型日粮中含有适量的淀粉(8.5%~16.9%)可提高纤维素、半纤维素的消化率,增加到达小肠的瘤胃微生物蛋白量。但如果淀粉含量过高,则造成纤维素、半纤维素的消化率降低,到达小肠的瘤胃微生物蛋白、饲料蛋白质和总粗蛋白质量减少。     

脲酶抑制剂对绵羊瘤胃发酵特性的影响

选用 12只瘘管公羊研究氢醌对瘤胃发酵特性的影响。以始重为区组 ,随机将动物分成 4个处理组 ,即在全混合日粮中分别添加 0、2 0、4 0和 80mg/kg氢醌 (干物质基础 )。在采食后 0、2、4、6和 8小时采集瘤胃液样本立即测定瘤胃液的氨浓度和pH值 ,随后测定挥发性脂肪酸和尿素氮含量。不同采样点的瘤胃液pH值不受添加氢醌的影响。在采食后 2小时 ,喂含有氢醌日粮的各试验组瘤胃氨的浓度比对照组低近一半 (P <0 .0 5 )。在 0、6、8小时各处理组NH3 的浓度差异不显著 (P >0 .0 5 )。在采食后 4小时 ,除 80mg/kg组外 ,各试验组氨的浓度与对照组相比 ,差异不显著(P >0 .0 5 )。随着氢醌添加水平的增加 ,对尿素水解的抑制作用增强 ,结果导致尿素在瘤胃中积累的增加 ,这和氨的浓度在不同时间点随氢醌添加水平增加而相应减少的变化趋势是相对应的。日粮中添加 2 0 ,4 0和 80mg/kg氢醌的各处理组乙酸、丙酸和丁酸的总产量分别比对照组提高 2 5 %、4 0 %和 2 6 % ,均达到显著水平 (P <0 .0 5 )。     

饲喂啤酒花茎叶对绵羊瘤胃代谢和增重的影响

测定表明，风干的啤酒花剪花后茎叶中粗蛋白质的含量为18.44%，高于蚕豆茎叶粗蛋白质的含量，用装有瘤胃瘘管的两只绵羊，在饲喂蚕豆茎叶和饲喂啤酒花茎叶的不同条件下，观测了瘤胃内pH、氨氮和蛋白质含量信增重的白天动态变化。结果表明，无在饲喂蚕豆茎叶期（Ⅰ期），还是在饲喂啤酒花茎叶期（Ⅱ期），绵羊瘤胃液中pH均呈碱性，在中牛14时pH值最低。Ⅱ期的pH值低于Ⅰ期。瘤胃淮中氨氮的含量Ⅱ期高于Ⅰ期，而蛋白质的含量Ⅰ期高于Ⅱ期，Ⅱ期对体重变化不明显。可以认为啤酒花剪花后茎叶是反刍动物的一种较好的越冬粗饲料。     

新型脲酶抑制剂对绵羊瘤胃酶活性和细菌总数的影响

为了研究新型脲酶抑制剂对绵羊瘤胃酶活性和细菌总数的影响 ,进行了两个实验。实验一 ,采用反转设计 ,用4头装有瘤胃瘘管的绵羊 ,分别测定了瘤胃液中脲酶、纤维素酶、蛋白水解酶、总脱氢酶的活性和瘤胃细菌总数。结果表明 ,在瘤胃内灌注50mg脲酶抑制剂 (氢醌 ,HQ )可以使脲酶的活性降低65 % (P<0.01) ,使纤维素酶的活性提高28 % (P<0.05) ,对蛋白水解酶、总脱氢酶的活性和瘤胃细菌总数没有影响(P>0.05)。实验二 ,采用滤纸片法观察了氢醌在10、20、40和80mg/L浓度范围内对瘤胃微生物的抑制作用。测定结果表明 ,除了80mg/L氢醌对瘤胃微生物有微弱的抑制作用外 ,其它浓度的氢醌对瘤胃微生物的生长没有影响。上述结果表明 ,HQ是瘤胃微生物脲酶的专一性抑制剂 ,对瘤胃微生物的繁殖和代谢活性无不良影响。HQ在较低浓度范围内使用 ,就可以非常有效地减缓瘤胃中尿素的释放速度 ,对瘤胃微生物和宿主动物安全 ,无毒副作用 ,在反刍动物尿素利用方面具有非常大的开发潜力。     

添喂赖氨酸及赖氨酸席夫碱对绵羊瘤胃发酵的影响

选取4只安装永久性瘤胃瘘管的中国美利奴(新疆型)细毛羊,采用4×4拉丁方设计,分别添喂2、4 g/d赖氨酸席夫碱和24、g/d赖氨酸对照(以赖氨酸含量计),以研究其对瘤胃发酵的影响。结果表明:添喂赖氨酸席夫碱4 g/d组瘤胃乙酸和总挥发性脂肪酸浓度分别低于赖氨酸4 g/d组9.44%和7.24%(P<0.05)。赖氨酸席夫碱添喂量从2 g/d增加到4g/d时,丙酸和丁酸平均含量分别增加了8.20%和10.64%(P<0.05)。添喂赖氨酸席夫碱,绵羊干物质采食量、瘤胃pH值和NH3-N浓度分别在1 374.21~1 419.01 g、6.14~6.54和11.31~28.21 mg/100 mL范围之间,各组无显著差异。以上结果说明:添喂赖氨酸席夫碱比添喂赖氨酸降低了瘤胃乙酸和总挥发性脂肪酸浓度,改变了瘤胃发酵类型。     

绵羊消化道不同取样部位和不同灌注方法对流通速率测值的影响研究

本实验将１８头内蒙古半细毛羊随机分成２组，采用一次性和连续灌注技术研究了不同灌注方法和不同取样部位对绵羊流通速率测定值的影响。结果表明：无论是一次性灌注还是连续灌注，绵羊从瘤胃、十二指肠到直肠的流通速率皆呈递降趋势，而且在三部位测定的流通速率之间存在明显的相关性。连续灌注时瘤胃和十二批肠的流通速率显著高于直肠流通速率（Ｐ＜０．０５）；一次性灌注者，瘤胃、十二批肠和直肠部位的流通速率之间相关性较强（     

不同添加水平多聚甲醛对绵羊瘤胃微生物数量及消化酶活性的影响

将5只体重(55.6±3.2)kg、2～3岁、装置了永久性瘤胃瘘管的小尾寒羊公羊,按5×5拉丁方设计,在饲喂相同日粮条件下,在5期试验中分别添喂0、150、300、450和600 mg/kg多聚甲醛,测定瘤胃液pH,氨态氮及挥发性脂肪酸浓度,内纤维素酶、外纤维素酶、纤维二糖酶、木聚糖酶、果胶酶、淀粉酶和蛋白酶活性,并进行原虫、细菌显微镜分类和真菌PCR计数,以研究不同添加剂量多聚甲醛对绵羊瘤胃微生物及消化酶活性的影响。结果表明,与对照组相比,添喂150、300、450和600 mg/kg多聚甲醛,绵羊的干物质自由采食量分别增加2.3%(P>0.05)、22.1%(P<0.01)、7.5%(P<0.01)和-6.6%(P<0.01);瘤胃液原虫总数分别减少14.2%、62.5%、72.6%和85.3%(P<0.01);而细菌总数分别增加35.8%、93.8%、-6.8%和-24.2%(P<0.01);真菌拷贝数分别增加2.0%(P>0.05)、5.4%(P>0.05)、14.3%(P<0.01)和26.8%(P<0.01);氨态氮分别降低9.0%、12.0%、14.9%和20.9%(P<0.01);挥发性脂肪酸分别提高2.4%(P>0.05)、-0.3%(P>0.05)、-1.3%(P>0.05)和-10.3%(P<0.01);内纤维素酶活性分别提高6.5%、22.4%、-10.2%和-19.2%(P<0.01);外纤维素酶活性分别提高3.4%(P>0.05)、17.5%(P<0.01)、-18.0%(P<0.01)和-25.7%(P<0.01);纤维二糖酶活性分别提高8.3%、23.7%、-24.9%和-31.8%(P<0.01);淀粉酶活性分别提高2.8%、8.6%、16.0%和23.3%(P<0.01);果胶酶活性分别降低11.8%、12.1%、11.2%和11.1%(P<0.01);蛋白酶活性分别降低10.9%、30.4%、49.6%和56.2%(P<0.01);而木聚糖酶活性没有显著变化(P>0.05)。综合试验结果,多聚甲醛添喂剂量为300 mg/kg时,绵羊的自由采食量最高,此时瘤胃液原虫数量减少而细菌总数最多、纤维素酶活性最高。     

过瘤胃葡萄糖和缓释尿素对热应激绵羊生产性能及瘤胃发酵功能的影响

【目的】 本试验旨在研究饲粮中添加缓释尿素（SRU）和过瘤胃葡萄糖（RPG）对热应激绵羊生产性能和瘤胃发酵功能的影响。【方法】 选取40只健康、体重相近的3月龄湖羊公羔,按初始体重随机分成4个处理组（n=10）,分别为对照组（CON组,饲喂基础饲粮）、缓释尿素组（SRU组,基础饲粮中添加缓释尿素15 g/d）、过瘤胃葡萄糖组（RPG组,基础饲粮中添加过瘤胃葡萄糖10 g/d）和联合添加组（UG组,基础饲粮中添加缓释尿素15 g/d+过瘤胃葡萄糖10 g/d）,预饲期15 d,正饲期50 d。在正饲期的最后一天晨饲前,分别采集血液和瘤胃液,测定血样中免疫球蛋白A （IgA）、免疫球蛋白M （IgM）、免疫球蛋白G （IgG）、肿瘤坏死因子-α（TNF-α）、白细胞介素-2（IL-2）的含量,并测定瘤胃液pH、氨态氮、微生物蛋白及挥发性脂肪酸等指标。【结果】 与CON组相比,①饲粮中添加缓释尿素、过瘤胃葡萄糖均显著降低热应激绵羊的呼吸频率（P<0.05）,UG组热应激绵羊的直肠温度显著降低（P<0.05）。②SRU组、RPG组、UG组热应激绵羊的终末体重和平均日增重均显著提高（P<0.05）,料重比显著降低（P<0.05）。③RPG组和UG组热应激绵羊血清中IgG和IgM的含量均显著提高（P<0.05）,血清中TNF-α和IL-2的含量显著降低（P<0.05）。④各处理组热应激绵羊瘤胃内乙酸与丙酸的比值均显著提高（P<0.05）,SRU组瘤胃内乙酸、异丁酸、异戊酸比例和总挥发性脂肪酸的浓度均显著提高（P<0.05）,RPG组瘤胃液pH和异戊酸比例均显著提高（P<0.05）,瘤胃内氨态氮、丙酸、丁酸的比例均显著降低（P<0.05）,UG组瘤胃内乙酸、总挥发性脂肪酸及微生物蛋白的含量均显著提高（P<0.05）。【结论】 饲粮中添加缓释尿素、过瘤胃葡萄糖显著提高了热应激绵羊的生产性能,改善瘤胃发酵,维持瘤胃内环境的稳定,可有效缓解绵羊热应激。     

不同钴水平对肉用绵羊瘤胃维生素B12合成、瘤胃发酵及造血机能的影响

本试验研究不同钴水平对肉羊维生素B1 2的合成、瘤胃发酵及造血机能的影响。2 0只健康、体重相近(2 7.3±0.9)kg的杂交一代羯羊,平均分为5组,分别饲喂基础日粮(含钴0.0 8 6 mg/kg)、基础日粮中添加0.2 5、0.5 0、0.7 5和1.00 mg/kg钴的试验组日粮,饲粮进食量相同,试验期8周。结果表明,基础日粮中0.086 mg/kg的钴不能满足肉羊的需要,添加0.25~1.00 mg/kg钴,可促进瘤胃维生素B12的合成,其合成量随饲喂时间的延长而增加,6周后趋于稳定,第6、8周的平均值为31.70~44.83 nmol/L,钴的添加量低于0.50 mg/kg时瘤胃维生素B12的含量增加较快,超过该量增加的幅度延缓。添加0.50 mg/kg的钴可显著增加瘤胃总挥发性脂肪酸的产生量并使其中丙酸比例增加、异丁酸和异戊酸比例降低。添加0.25 mg/kg的钴即可维持正常的造血功能。建议肉羊日粮中钴的适宜添加水平为0.25~0.50 mg/kg(即适宜日粮钴水平为0.336~0.586 mg/kg)。     

Influence of kanamycin on the rumen bacteria and ammonia production in supplemented sheep rumen liquor in vitro

Bacteriological studies were made with in vitro sheep ruminal fluids supplemented with synthetic fodder containing different amounts of kanamycin (0.125, 2.50, and 60 mg/ml), during anaerobic incubation at 38–39°C for 6 h.Changes in the bacterial population occurred in the presence of large amounts (60 mg/ml) of kanamycin, and the B₁-type strain of Eubacterium became predominant.The marked increase in the concentration of ammonia in the supplemented rumen liquor, obtained after anaerobic incubation with high dosages of this antibiotic, is discussed.     

Digesta flows in sheep fed poor-quality hay supplemented with urea and carbohydrates

Two metabolism trials were conducted with 12 yearling crossbred wethers per trial (34 and 38 kg for trials 1 and 2, respectively). The wethers, equipped with ruminal, abomasal and ileal cannulae, were randomly allotted for each trial to the following treatments: 1) hay alone or hay supplemented with 2) .9% urea, 3) 1% urea and 6.5% molasses or 4) 1% urea and 5.2% corn. Two digestive flow markers were used: Cr2O3 powder and Co-ethylenediaminetetraacetic acid (Co-EDTA). Urea and Co-EDTA were infused continuously into the rumen via cannula. Daily dry matter (DM) intake averaged 517 g. Urea supplementation improved N retention (P less than .01). Apparent digestibility of DM, acid detergent fiber (ADF) and energy was not affected by treatment. Urea and carbohydrate supplementation increased ruminal propionic acid molar proportions (P less than .05). Apparent ruminal DM digestion accounted for 41% of the total DM degraded, whereas 77.4% of the digestible ADF was degraded in the rumen. Urea supplementation increased ADF digestion in the large intestine (P less than .01). Urea and carbohydrate supplementation resulted in a stepwise increase in N flowing with the liquid phase at the abomasum. Mean retention times of the solid and liquid phases of digestive contents were similar across treatments. Overall, benefits of supplementation of poor-quality fescue hay diets by small amounts of urea and readily available carbohydrates remain questionable for sheep fed at a fixed level of intake below maintenance.     

Levels of milk urea, plasma constituents and rumen liquid ammonia in relation to the feeding of dairy cows during early lactation

The study was undertaken to establish the relationships between milk and plasma urea levels and protein supply, using traditional and new measures of feed protein value. Samples of milk and plasma were taken before morning feeding twice weekly for the first 3 months post partum from 21 multiparous cows and 7 heifers. Samples of rumen fluid were collected every second week. The cows were distributed into 4 different feeding groups. Feeding regimens were factorial with respect to protein content of the concentrates (i.e. Low protein (Lp): 12.5% digestible crude protein (DCP) vs. High protein (Hp): 17.5% DCP) and concentrate allowances (i.e. Low energy (Le): substandard vs. High energy (He): standard). Silage was offered ad libitum. The within-animal coefficients of correlation between milk and plasma urea levels, and between milk urea levels and the levels of ammonia in the rumen fluid wer r = 0.88 (p less than 0.001) and r = 0.75 (p less than 0.001), respectively. Analysis of variance showed the following sources of urea variation to be significant: Protein balance in the rumen (PBV), intake of DCP, intake of amino acids absorbed in the intestine (AAT), intake of fattening feed units, and the individual animal factor. A similar tendency was found for the variation of ammonia in rumen fluid. The coefficients of determination (R2 model) were not increased by introducing protein balance (BADCP), the amount of PBV and AAT in the dry matter ingested, or the protein/energy ratio as alternative parameters of protein intake in the models. The levels of protein or energy intake did not significantly influence the levels of plasma albumin. The correlations between urea levels and other plasma indicators of metabolic status and liver function were generally low.     

Animal,feed and rumen fermentation attributes associated with methane emissions from sheep fed brassica crops

Methane emissions from ruminants enhance global warming and lead to a loss of feed energy. The emissions are low when fed brassica crops, but the factors contributing to low emissions are unknown. A meta-analysis was conducted with individual animal data collected from seven experiments. In these experiments, methane emissions were measured using respiration chambers. Animal characteristics, feed chemical composition and rumen fermentation parameters were included for the analysis using multiple regression models. Feed intake level, animal live weight and age were animal factors that were weakly and negatively related to methane yield (g/dry matter intake). The duration in which sheep were fed brassica crops was a significant contributor in the model, suggesting that the effect on emissions diminishes with time. Among a range of feed chemical composition characters, acid detergent fibre and hot-water-soluble carbohydrate contributed significantly to the model, suggesting that both structural and soluble carbohydrates affect methane formation in the rumen. There was no significant correlation between the concentration of sulphate in brassicas and emissions, but nitrate was moderately and negatively correlated with methane yield (r = −.53). Short-chain fatty acid profiles in the rumen of animals fed brassicas were different from those fed pasture, but these parameters only moderately correlated to methane emissions (r = .42). Feeding forage rape resulted in low rumen pH. The pH before morning feeding was strongly correlated to methane yield (r = .90). Rumen pH, together with microbial communities mediated by pH, might lead to low emissions. Bacteria known to produce hydrogen were relatively less abundant in the rumen contents of brassica-fed animals than pasture-fed animals. In conclusion, animal and feed factors, rumen fermentation and microbial communities all affect methane emissions to some extent. The interactions of these factors with each other thus contribute to methane emissions from brassica-fed sheep.     

Volatile fatty acids in the rumen of sheep fed a synthetic diet

A trial was conducted with wethers to study the effect of the administration of a synthetic diet (composition: 30.125% starch, 30.125% sucrose, 25% cellulose, 5.25% urea, 8.125% mineral supplement, 1.25% maize oil and 0.125% cholinechloride) upon rumen fermentation. The adaptation to the synthetic diet lasted three months, the proportion of the synthetic diet increasing every week (by 10%) to the detriment of a traditional diet (composition: 0.5 kg meadow hay, 0.3 kg barley, 0.2 kg wheat bran, salt and straw ad libitum). In the 10th week the animals consumed 0.5 kg granular synthetic diet, 0.2 kg cellulose flakes and 0.01 kg polystyrene. After three weeks of the administration of the fully synthetic diet, the rumen fluid was sampled after morning feeding in intervals of 0, 1, 3, 5 and 7 hours. In the dynamics of fermentation, statistically significant differences were found only in isobutyric and isovaleric acid between the 0th and 1st and between the 5th and 7th hours (P less than 0.05--P less than 0.001). The data for all the time intervals were recalculated to average values. These were as follows: total volatile fatty acids 63.03 mmol/l, acetic acid 51.00 mol%, propionic acid 26.75 mol%, butyric acid 19.43 mol%, isobutyric acid 0.91 mol%, isovaleric 1.27 mol%, valeric acid 0.62 mol%, energy efficiency of VFA production 78.23%. The obtained data are confronted with literary data on synthetic diets which contained urea and various energy sources.     

饲养水平对阿勒泰羊胃肠道发育、瘤胃发酵参数及瘤胃微生物区系的影响

为研究饲养水平对阿勒泰羊胃肠道发育、瘤胃发酵参数、消化酶活性及瘤胃微生物区系的影响,选取月龄相近(3～3.5月龄)、体重均一(19.16±0.54)kg、臀型一致、健康状况良好的阿勒泰母羔羊30只,随机分为3组,每组10只,自由采食60 d后,参照NRC(2007)饲养标准中维持能量(Em)需要,3个组分别按1.5Em...