大蒜素对瘤胃发酵和甲烷产量的影响

大蒜素能调控瘤胃发酵模式,明显降低瘤胃甲烷产量,降低氨态氮浓度.本文综述了大蒜素及其抑茵机制,以及大蒜素对甲烷产量和瘤胃发酵的影响.     

犊牛生产体系和断奶后的管理对其生长性能的影响

文章旨在评估犊牛生产系统和断奶后管理对其生长性能和胴体特征的影响。试验采用2×2因子设计,两个生产系统(在玉米秸秆上饲养和在干燥环境饲养),两个断奶后的管理(直接育肥和采用生长-育肥两阶段饲养)。结果显示:与冬季在干燥环境饲养的牛相比,冬季在玉米秸秆上过冬的犊牛初始体重较轻(P <0.05)。同时,冬季在干燥环境下饲养的犊牛较在玉米秸秆上过冬的犊牛日增重显著提高(P <0.05)。前期在玉米秸秆上过冬的犊牛在生长-育肥期的初始体重显著低于在干燥环境饲养犊牛(P <0.05)。但在玉米秸秆上过冬的犊牛较干燥环境饲养的犊牛存在代偿性反应特征,表现为日增重和饲料报酬显著提高(P <0.05)。在评价断奶后管理对生长性能的影响时,生长-育肥期犊牛较育肥期犊牛初始体重、末重和干物质摄入量显著提高(P <0.05)。但与生长-育肥期犊牛相比,育肥期犊牛日增重和饲料报酬显著提高(P <0.05)。断奶后的管理和生产体系对大理石纹的影响具有显著交互效应(P <0.05)。在玉米秸秆上过冬的生长-育肥组较其他组显著提高了大理石纹评分(P <0.05)。结论:与断奶后直接饲喂育肥期饲料的犊牛相比,采用生长-育肥两阶段饲喂方式的犊牛胴体重量显著提高。然而,直接饲喂育肥料的犊牛饲料报酬和日增重均提高,两阶段饲喂方式的犊牛在经济收益上无显著差异。     

Effects of pure plant secondary metabolites on methane production,rumen fermentation and rumen bacteria populations in vitro

In this study, the effects of seven pure plant secondary metabolites (PSM s) on rumen fermentation, methane (CH₄) production and rumen bacterial community composition were determined. Two in vitro trials were conducted. In trial 1, nine concentrations of 8‐hydroxyquinoline, α‐ terpineol, camphor, bornyl acetate, α‐ pinene, thymoquinone and thymol were incubated on separate days using in vitro 24‐hr batch incubations. All compounds tested demonstrated the ability to alter rumen fermentation parameters and decrease CH₄ production. However, effective concentrations differed among individual PSM s. The lowest concentrations that reduced (p  <  .05) CH₄ production were as follows: 8 mg/L of 8‐hydroxyquinoline, 120 mg/L of thymoquinone, 240 mg/L of thymol and 480 mg/L of α‐ terpineol, camphor, bornyl acetate and α‐ pinene. These concentrations were selected for use in trial 2. In trial 2, PSM s were incubated in one run. Methane was decreased (p  <  .05) by all PSM s at selected concentrations. However, only 8‐hydroxyquinoline, bornyl acetate and thymoquinone decreased (p  <  .05) CH₄ relative to volatile fatty acids (VFA s). Based on denaturing gradient gel electrophoresis analysis, different PSM s changed the composition of bacterial communities to different extents. As revealed by Ion Torrent sequencing, the effects of PSM s on relative abundance were most pronounced in the predominant families, especially in Lachnospiraceae , Succinivibrionaceae , Prevotellaceae , unclassified Clostridiales and Ruminococcaceae . The CH ₄ production was correlated negatively (?.72; p  <  .05) with relative abundance of Succinivibrionaceae and positively with relative abundance of Ruminococcaceae (.86; p  <  .05). In summary, this study identified three pure PSM s (8hydroxyquinoline, bornyl acetate and thymoquinone) with potentially promising effects on rumen CH₄ production. The PSM s tested in this study demonstrated considerable impact on rumen bacterial communities even at the lowest concentrations that decreased CH₄ production. The findings from this study may help to elucidate how PSM s affect rumen bacterial fermentation.     

体外法研究延胡索酸二钠对瘤胃微生物发酵活力及甲烷产量的影响

为探讨延胡索酸二钠对瘤胃甲烷产量及瘤胃微生物发酵活力的影响,本研究共设计了3个试验来阐明该问题。试验1采用体外批次培养,研究了不同日粮条件下(高牧草日粮、中等水平牧草的日粮和低牧草日粮)添加延胡索酸二钠(0,4和7mmol/L)对山羊瘤胃微生物发酵及甲烷产量的影响。结果表明,较对照相比,添加延胡索酸二钠显著提高了累积产气量、pH值和TVFA产量(P<0.05),降低了甲烷产量(P<0.05),其中高牧草日粮组下降幅度最大。试验2探讨了延胡索酸二钠对黄化瘤胃球菌发酵粗饲料活力的影响。结果表明,与对照组相比;添加延胡索酸二钠显著提高了黄化瘤胃球菌数量及其对黑麦草的降解率(P<0.05);试验3探讨了延胡索酸二钠对瘤胃真菌发酵粗饲料活力的影响,结果显示,延胡索酸二钠显著降低了厌氧真菌发酵的总产气量、干物质消失率及羧甲基纤维素酶酶活(P<0.05)。结果说明,延胡索酸二钠在降低甲烷产量方面与发酵底物的天然特性有关,其中对高牧草日粮的作用效应最为显著;延胡索酸二钠可提高瘤胃混合微生物与瘤胃纤维降解菌发酵粗饲料的能力,但对瘤胃真菌的发酵活力具有抑制效应。     

Effects of protozoa on bacterial nitrogen recycling in the rumen

The effects of protozoa on ruminal NH3-N kinetics and bacterial N recycling were measured in five sheep (57.6+/-7.1 kg BW, x +/- SD) with ruminal and duodenal cannulas in naturally faunated, defaunated, and refaunated periods. The sheep were fed a diet of 239 g of alfalfa haylage and 814 g of barley concentrate per day (DM basis) divided into 12 equal portions and allocated at 2-h intervals. A pulse dose of 300 mg of 15N as [15N]NH4Cl was administered into the rumen (on d 1 and 15) and 300 mg of 15N as [15N]urea was administered intravenously to the blood (d 8). Enrichment of 15N was measured in ruminal NH3-N, bacterial N, and plasma urea N over a period of 35 h. Total collection of urine was made for 5 d and analyzed for purine derivatives to calculate the flow of microbial N. Ruminal parameters and nutrient digestibilities were also measured. Sheep were defaunated using a rumen washing procedure 50 d prior to measurements in the defaunated period. Sheep were refaunated with ruminal contents from a faunated sheep receiving the same diet. Measurements began 26 d following refaunation, at which time protozoal numbers had returned to those in the originally faunated sheep. Data reported in parentheses are for faunated, defaunated, and refaunated sheep, respectively. Total culturable and cellulolytic bacterial numbers were unaffected by defaunation, but there was an increase in flow of microbial N from the rumen (10.8, 17.3, and 11.1 g N/d; P < .05) in the defaunated period. Flux, irreversible loss, and intraruminal recycling of NH3-N and recycling of NH3-N from plasma urea N were not affected by defaunation. Defaunation had no effect on reducing the absolute amount (13.8, 10.0, and 11.3 g N/d; P > .20) of bacterial N recycling and the percentage of N flux through the bacterial N pool. Total-tract digestion was reduced in defaunated compared with faunated sheep by 8, 17, 15, and 32% for OM, N, NDF, and ADF, respectively. In conclusion, defaunation improved ruminal N metabolism through the enhancement of bacterial protein synthesis, and improvement in the flow of microbial protein to the host animal.     

延胡索酸二钠对断奶羔羊瘤胃发育及瘤胃发酵功能的影响

为了研究日粮中添加延胡索酸二钠对断奶羔羊瘤胃发育及瘤胃发酵功能的影响,选用30只日龄为(50±5)d、体重为(25±2)kg的公羔,随机分为3组,每组10只。对照组饲喂基础日粮,试验组在基础日粮的基础上添加0.5%(Ⅰ组)和1%(Ⅱ组)的延胡索酸二钠,试验期70 d。结果显示:1试验Ⅰ、Ⅱ组断奶羔羊体增重比对照组分别增重3.2%(P0.05)和55.5%(P0.05);试验Ⅰ、Ⅱ组瘤胃净重比对照组分别高8.5%(P0.05)和26.4%(P0.01),Ⅰ和Ⅱ组间差异显著(P0.05);试验Ⅰ、Ⅱ组断奶羔羊瘤胃乳头高度比对照组分别高8.2%和9.2%,Ⅱ组乳头密度比对照组降低16.2%,各组间差异均不显著(P0.05)。2Ⅰ和Ⅱ组瘤胃p H值比对照组高(P=0.08);Ⅰ和Ⅱ组瘤胃氨态氮(NH3-N)浓度比对照组分别降低29.7%(P0.05)和21.0%(P0.05);Ⅰ和Ⅱ组瘤胃内容物中乳酸浓度分别比对照组降低27.0%(P0.01)和19.5%(P0.01);乙酸、丙酸、丁酸、乙酸/丙酸和总挥发性脂肪酸(TVFA)浓度3组间差异不显著(P0.05)。结果提示:日粮中添加延胡索酸二钠提高了断奶羔羊的体增重及瘤胃净重和瘤胃p H值,降低了瘤胃内氨态氮及乳酸浓度。     

Effects of supplemental tallow on rumen ciliated protozoa in feedlot cattle

Ruminal samples were collected at slaughter from 98 steers consuming a high-grain diet and receiving either no fat, or 2, 4, 6, or 8% supplemental tallow. Tallow supplementation tended (P = 0.11) to increase average ciliated protozoan numbers, however, the occurrence of defaunated animals was higher in the 8% fat treatment than in the control group. Entodinium spp. were the only protozoans that survived in all treatments, and total numbers ranged up to 3.2 x 10(6)/g of ruminal contents. Although increasing tallow supplementation induced a defaunating effect in many animals, the response was unpredictable and protozoa occasionally proliferated irrespective of fat level.     

微生态制剂对犊牦牛瘤胃发酵和免疫力的影响

旨在探讨微生态制剂对青海犊牦牛瘤胃发酵和免疫力的影响,以期为微生态制剂在青海牦牛养殖生产中的推广应用提供参考依据。将45只青海犊牦牛随机分成3组(对照组、试验Ⅰ组、试验Ⅱ组),分别在精饲料中添加0、0.5、1.0 g/kg的微生态制剂,测定各处理组试验牛日增重等生长性能指标和瘤胃液中pH值、氨态氮浓度、挥发性脂肪酸浓度等瘤胃发酵指标,以及免疫球蛋白含量、细胞因子含量等免疫力指标。结果显示:试验Ⅰ组、Ⅱ组与对照组相比,平均日增重、氨态氮、乙酸、丁酸、总挥发性脂肪酸、IgG、IgA、IL-2、IFN-γ含量均显著提高(P0.05);试验Ⅱ组与试验Ⅰ组相比,平均日增重、IgG、IL-2、IFN-γ含量均显著提高(P0.05)。结果提示添加0.5 g/kg和1.0 g/kg微生态制剂均能显著提高青海犊牦牛的增重、瘤胃发酵和免疫力,提高牦牛养殖经济效益。     

Production of volatile fatty acids in the rumen of calves during dietary-microbial stimulation and early weaning

The contents of volatile fatty acids in the rumen fluid were studied in calves at an early (seven weeks of age) and traditional weaning term (nine weeks of age). Weaning at the age of seven weeks enabled to save 16.2 kg of milk replacer per calf; there was also a lower content of concentrates in the starter feed with a supplement of Amylastim. The health condition of the calves was good in both groups. The average daily weight gains for the period from the second to the ninth week of age were 0.550 kg in the early weaned calves and 0.690 kg in the calves weaned at a normal time. Early weaning had a positive influence on the development of rumen metabolism. Calves weaned at the age of seven weeks, compared with those weaned at the age of nine weeks, had much higher concentrations of VFA (p less than 0.05) in rumen fluid (at the age of seven weeks: 130.49 mmol per litre vs. 111.53 mmol per litre; at the age of eight weeks: 119.74 mmol per litre vs. 96.98 mmol per litre). Early weaned calves had the statistically significantly (p less than 0.05) higher proportions of propionic acid, butyric acid, i-butyric acid, and valeric acid. Later-weaned calves had the significantly higher (p less than 0.05) contents of acetic acid and i-valeric acid.     

Quantitative studies of the in vitro production of pipecolic acid by rumen protozoa and its degradation by rumen bacteria

An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species‐enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L‐lysine (1.0 mmol/L L‐Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L‐Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L‐Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D‐Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D‐Lys, though at a lower rate (1/3) compared with L‐Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L‐ or D‐Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D‐Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen‐produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.     

青贮金针菇对荷斯坦奶牛瘤胃发酵、甲烷排放及原生动物数量的影响

文章旨在研究不同水平青贮金针菇及尿素对奶牛养分消化率、瘤胃发酵、甲烷排放及原生动物数量的影响。试验选择15头荷斯坦奶牛[(542±68)kg],随机分为5组,每组3个重复,每个重复1头牛。试验一共设计5种日粮,对照组饲喂基础日粮,各处理组分别在基础饲粮中添加青贮金针菇,处理1组(90%青贮金针菇,10%玉米秸秆),处理2组(90%青贮金针菇,9%玉米秸秆,1%尿素),处理3组(80%青贮金针菇,20%玉米秸秆),处理4组(80%青贮金针菇,19%玉米秸秆,1%尿素)。试验期分为2周适应期和1周数据收集期。饲粮中添加青贮金针菇较对照组显著提高了酸性洗涤木质素的摄入量(P<0.05);金针菇添加水平和尿素对干物质和其他营养素的摄入量无显著影响(P>0.05)。与对照组相比,在处理组日粮中添加青贮金针菇显著增加总短链脂肪酸(SCFA)和丙酸含量(P<0.05),但乙酸含量及乙酸与丙酸比值显著降低(P<0.05)。添加青贮金针菇和尿素对短链脂肪酸含量有显著影响(P<0.05)。日粮添加80%青贮金针菇和1%尿素时,乙酸浓度显著高于未添加尿素组(P<0.05);青贮金针菇日粮添加尿素显著降低了瘤胃丁酸含量(P<0.05)。与对照组相比,在日粮中添加青贮金针菇可显著降低瘤胃原生动物总数(P<0.05)。饲粮中添加青贮金针菇可导致荷斯坦奶牛瘤胃原生动物总数逐步减少(P<0.05)。青贮金针菇日粮组中螺旋体数量显著高于对照组(P<0.05)。饲喂青贮金针菇的荷斯坦奶牛较对照组显著降低了甲烷排放量(P<0.05)。综上所述,用金针菇废弃底物与尿素、玉米秸秆混合日粮可以提高奶牛日粮的营养价值,日粮添加青贮金针菇显著降低了奶牛瘤胃原生动物种群和肠道甲烷排放量。     

Effects of rare earth element lanthanum on rumen methane and volatile fatty acid production and microbial flora in vitro

The objectives of the trial were to study the effects of rare earth element (REE) lanthanum (La) on the in vitro rumen methane (CH₄) and volatile fatty acid (VFA) production and the microbial flora of feeds. Four feed mixtures with different levels of neutral detergent fibre (NDF), that is 20.0% (I), 31.0% (II), 41.9% (III) and 52.7% (IV), were formulated as substrates. Five levels of LaCl₃, that is 0, 0.4, 0.6, 0.8 and 1.0 mmol/kg dry matter (DM), were added to the feed mixtures, respectively, as experimental treatments in a two‐factor 5 × 4 randomized design. The in vitro incubation lasted for 24 h. The results showed that supplementing LaCl₃ increased the total gas (p < 0.001) production and tended to increase the total VFA production (p = 0.072) and decreased the CH₄ production (p = 0.001) and the ratios of acetate/propionate (p = 0.019) and CH₄/total VFA (p < 0.001). Interactions between LaCl₃ and NDF were significant in total gas production (p = 0.030) and tended to be significant in CH₄ production (p = 0.071). Supplementing LaCl₃ at the level of 0.8 mmol/g DM decreased the relative abundance of methanogens and protozoa in the total bacterial 16S rDNA analysed using the real‐time PCR (p < 0.0001), increased F. succinogenes (p = 0.0003) and decreased R. flavefaciens (p < 0.0001) whereas did not affect R. albus and anaerobic fungi (p > 0.05). It was concluded that LaCl₃ decreased the CH₄ production without negatively affecting feed digestion through manipulating rumen microbial flora when feed mixtures with different levels of NDF were used as substrates.     

Morphological and functional development of the rumen in the calf: influence of the time of weaning. 1. Morphological development of rumen mucosa.

The objective of this study was to determine whether the nutritional regimen of rearing calves would influence the morphometric and histological development of rumen mucosa. Twelve male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I), early weaned (6 weeks) group (II) and late weaned (9 weeks) group (III). All animals received additional solid feed. Animals of group I were slaughtered after 6 weeks of age, whereas those in groups II and III were slaughtered after 9 weeks of age. At slaughter, the ruminal digesta amounted to 2035 g (milk group), 3092 g (late weaned group) and 5374 g (early weaned group). The differences in the ruminal molar percentage of SCFA were not significant. There was a trend for lower pH and higher SCFA concentrations in the order late weaned, early weaned and milk fed animals (pH: 6.4, 6.6 and 6.7, respectively; SCFA: 96, 87 and 77 mmol/l, respectively). The mean length (1.07 mm in milk group, 1.45 mm in late weaned group and 1.87 mm in early weaned group), width (0.43, 0.58 and 0.71 mm, respectively) and surface of papillae (190, 232 and 241 mm2/cm2 mucosa, respectively) increased with both the age of the animals and the elevated intake of solid feed, whereas the number of papillae (210, 140 and 92 per cm2 mucosa, respectively) decreased. In both milk-fed groups type A and B corneal cells were present in the Stratum corneum, whereas in the earlier weaned calves type C-cells could be also seen. These findings indicate a more advanced stage of development of the rumen epithelium in the earlier weaned calves fed higher amounts of concentrate and hay.     

Effect of monensin on rumen ciliate protozoa in sheep

In a first experiment 4 rams consumed over a period of 70 days 0; 82; 208 and 345 mg of monensin daily, respectively. All doses of monensin caused a marked decrease in total numbers of rumen protozoa in samples taken after this period. More than 90% of total protozoal numbers belonged to the genus Entodinium. The sensitivity of the genus Entodinium to monensin was found to be lower than that of genera Dasytricha and Isotricha. In the second experiment 24 lambs were fed hay and concentrates in the ratio 60:40% (groups 1 and 2) and 40:60% (groups 3 and 4). Groups 2 and 4 received 40 mg monensin per animal daily during 16 weeks. The decrease in protozoal numbers due to monensin in samples taken after this period was significant (P less than 0.001) in lambs fed the concentrate diet (groups 3 and 4) and also in lambs from groups 1 and 2 fed the roughage diet (P less than 0.05). The statistical evaluation of the inhibition of total protozoal numbers by monensin (%) in lambs fed both diets has shown that the antiprotozoal effect of monensin was significantly more intensive with the concentrate diet (P less than 0.025) than with the roughage diet.     

不同厌氧处理方式对鲜麦秸品质、活体外瘤胃发酵及甲烷产量的影响

为研究不同厌氧处理方式对鲜麦秸品质、活体外瘤胃发酵及甲烷产量的影响,试验分为5个处理组,分别为全株微贮组、秸秆黄贮组、秸秆微贮组、秸秆氨化组和秸秆碱化组。其中全株微贮组、秸秆微贮组秸秆经铡切处理后分别喷洒5×104cfu/g混菌悬浮液,秸秆黄贮组喷洒相同质量的无菌水;秸秆氨化组按照干物质5%喷洒尿素溶液,秸秆碱化组按秸秆干物质4%喷洒生石灰熟化澄清液。结果表明:秸秆微贮组、全株微贮组感官性能优于其他处理组;与秸秆黄贮组相比,全株微贮组、秸秆微贮组、秸秆氨化组及秸秆碱化组粗蛋白质含量分别提高219.21%(P<0.05)、16.75%(P>0.05)、112.81%(P<0.05)、13.79%(P>0.05);全株微贮组的中性洗涤纤维、酸性洗涤纤维含量约是其他处理组的1/2(P<0.05);与秸秆黄贮组相比,秸秆微贮组、秸秆氨化组、秸秆碱化组中性洗涤纤维显著降低8.24%、13.01%、9.09%,酸性洗涤纤维显著降低17.67%、17.68%及15.61%;产气量:全株微贮组>秸秆氨化组>其他处理组;秸秆黄贮组比全株微贮组、秸秆氨化组体外消化率降低了56.39%、24.03%;与秸秆微贮组相比,全株微贮组体外发酵液NH3-N、TVFA、乙酸、丙酸、丁酸、戊酸、异丁酸及异戊酸含量分别提高41.29%、20.99%、10.48%、41.99%、14.61%、166.67%、43.75%及64.71%(P<0.05)。由此可知,秸秆氨化处理和全株小麦经微生物处理均可提高其感官性能,提升产气量、挥发酸及消化率,全株小麦经微生物处理性能优于各秸秆处理组。     

瘤胃原虫营养研究进展

瘤胃原虫是瘤胃微生物的重要组成部分。本文针对瘤胃原虫特点、作用、调控及瘤胃细菌和真菌间的相互作用作一综述。     

Research note: Postnatal development of electrolyte transport in calf rumen as affected by weaning time.

In a previous study we found a positive correlation between early weaning in calves and morphological parameters which were indicative of ruminal development, i.e. the length and width of the papillae. The objective of the present study was to determine to what extent this observation could be reflected by modulations of absorptive and secretory functions of the rumen mucosa. For this purpose the short-circuit currents (Isc) as a measure of electrogenic net ion fluxes and the transepithelial conductances (G(T)) as a measure of the overall tissue permeability were measured in vitro applying the Ussing-chamber technique. Simultaneously, the unidirectional flux rates of sodium and chloride across rumen wall epithelia were determined in the absence of electrochemical gradients. Under these conditions, significant positive net flux rates (Jnet) clearly indicate active mechanisms for electrolyte absorption. For the experiments 12 male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I, slaughtered after 6 weeks of age), late weaning group (II, slaughtered after 9 weeks of age) and early weaning group (II, weaned after 6 weeks of age and slaughtered after 9 weeks of age). Whereas G(T) values remained unaffected by different age and feeding, Isc values were significantly affected by early weaning but were not influenced by age. Irrespective of weaning time active absorption of Na+ tended to be higher by about 60% in 9 weeks old animals. Active absorption of chloride was significantly increased in milk fed 9 weeke old calves and this effect was further stimulated by early weaning. In conclusion, the data show an increasing active Na+ absorption with age in calf rumen that could not be influenced by early weaning. Similarly, active Cl- absorption was initially increased during postnatal development and this effect could be stimulated further by early weaning.     

精氨酸水平对梅花鹿仔鹿瘤胃发酵参数和菌群结构的影响

为研究精氨酸水平对离乳期梅花鹿瘤胃发酵参数和微生物菌群结构的影响,试验选择3月龄,体重相近的12只健康雄性梅花鹿,随机分为3组,每组4只。仔鹿饲喂蛋白质水平为12.28%的低蛋白质饲粮,精氨酸水平分别为0.80%(A组)、1.08%(B组)、1.26%(C组),试验期50 d。在试验期的最后1 d抽取仔鹿瘤胃液20 mL,一部分用于测定瘤胃发酵参数,一部分用于提取DNA分析瘤胃细菌多样性。结果表明：1)B组氨态氮含量极显著高于C组（P<0.01）;B组乙酸、丁酸、异丁酸含量极显著低于A组（P<0.01）,总挥发性脂肪酸含量显著低于A组（P<0.05）;B组的乙丙比极显著低于A、C组（P<0.01）。2)B组ACE指数显著高于C组（P<0.05）,Chao1指数显著高于A、C组（P<0.05）,B组Simpson指数极显著高于A、C组（P<0.01）,Shannon指数则极显著低于A、C组（P<0.01）,A组细菌群落结构与B、C组差异显著（P<0.05）。3）在门水平上,B组拟杆菌门（Bacteroidetes）相对丰度极显著低于A...     

Effect of lasalocid, monensin and thiopeptin on rumen protozoa

The effects of lasalocid, monensin and thiopeptin on the total number and the generic composition of rumen protozoa were determined in vivo and in vitro. Feeding lasalocid or monensin to cattle on either high grain or high roughage diets reduced total protozoal counts. Addition of lasalocid or monensin (6 to 48 micrograms ml-1) to the in vitro rumen fermentation resulted in marked reduction in protozoal numbers. The inhibition was dose dependent. Thiopeptin had no effect on rumen protozoa either in vivo or in vitro. Among the protozoal types, holotrichs (Dasytricha, Isotricha and Charonina) were unaffected by either lasalocid or monensin. Among the entodiniomorphs, Entodinium, Diplodinium and Ophryoscolex were more sensitive than the other types. Ophryoscolex purkynei was more sensitive to monensin than to lasalocid. Protozoal inhibition by lasalocid and monensin was transient because prolonged antibiotic feeding resulted in the selection of a resistant population in the rumen of cattle.     

哺乳犊牛腹泻的防治

犊牛腹泻是哺乳期犊牛常见多发病之一，死亡率较高，多发生于出生后前三周，一般为胃肠消化功能紊乱。特征是消化不良和拉稀，顽固性腹泻可使犊牛衰竭而亡。腹泻分为营养性腹泻或饲养管理不当而使犊牛更易患病原性腹泻，其病原主要是大肠杆菌。