首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
研究了施硫肥S0(0kg/hm2)、S1(16.5kg/hm2)、S2(33.0kg/hm2)、S3(49.5kg/hm2)4个水平对河西走廊紫花苜蓿生物学性状、产量及营养品质的影响。结果表明:S1和S2处理显著增加了紫花苜蓿主茎长和侧茎长,S1的分枝数显著高于S2和S3处理,不同硫肥水平对紫花苜蓿主茎节数和侧茎节数没有显著影响;S3主根粗显著小于S0,S1和S2处理,S1主茎粗显著大于S0和S3处理;S1茎叶比显著低于其他处理的茎叶比;S1和S2显著增加了紫花苜蓿第1茬干草产量,S1的紫花苜蓿第2茬干草产量显著高于S2和S3处理,不同硫水平对紫花苜蓿第3茬干草产量没有显著影响,S1处理的紫花苜蓿总干草产量显著高于其他处理;S0紫花苜蓿粗蛋白含量显著低于其他处理;S1的粗脂肪含量显著高于S3处理;不同硫肥水平对紫花苜蓿粗纤维含量没有显著的影响;S1和S2的粗灰分含量显著高于S0和S3处理;S1中性和酸性洗涤纤维含量在所有处理中最低;S1处理的干物质采食量、可消化干物质和相对饲用价值都显著的低于其他处理。施硫肥水平为16.5kg/hm2时,有利于紫花苜蓿的生长、产量和营养价值的提高,而当硫肥量超过33.0kg/hm2时,紫花苜蓿干草产量和品质开始下降。  相似文献   

2.
The stability of alpha-tocopherol concentrations in sheep, cattle, and pig blood and plasma stored at different temperatures was examined. For all species, the vitamin was stable for at least 6 days in plasma stored at -20 C, 4 C, and 25 C and in blood stored at 4 C and 25 C. For sheep and cattle, the vitamin was stable for at least 6 days in plasma stored at 37 C, but it was unstable in blood from all species stored at 37 C and in pig plasma stored at 37 C.  相似文献   

3.
A pad equivalent for a dog was prepared as a substitute for the loss of footpad. In addition to the time course of formation on epidermal morphogenesis, we investigated expressions of alpha(6) integrin subunit as adhesive molecule, and laminin and type IV and VII collagens as extracellular matrices of basement membrane components. Epithelium of the pad equivalent was thick enough to be easily confirmed at 5 days at the air-liquid interface, but many creases appeared on it at 7 days, and it shrank at 10 and 14 days. Keratinocytes were increased in 4 to 5 cell layers at 1 day at the air-liquid interface, differentiating into basal cell layer. Granular and corneal cell layers were confirmed until 5 days, and maintained their shape at least until 14 days. Alpha 6 integrin was expressed at almost the same fluorescent intensity as native pad tissue at 1 day at the dermal-epidermal junction. Laminin and type IV collagen were intermittently expressed at 5 and 10 days, respectively, at the dermal-epidermal junction, and at 14 days the fluorescence showed almost the same intensity as native pad tissue. The expression of type VII collagen was discontinuous at 2 days at the dermal-epidermal junction, but remained as it was at 14 days. The present findings suggested that although the formation of anchoring fibrils in basement membrane was incomplete, the pad equivalent in the dog was reconstructed similar to a native pad by epidermal morphogenesis.  相似文献   

4.
The influence of temperature (10 degrees C and 20 degrees C) on pharmacokinetics and metabolism of sulphadimidine (SDM) in carp and trout was studied. At 20 degrees C a significantly lower level of distribution (Vdarea) and a significantly shorter elimination half-life (T(1/2)beta) was achieved in both species compared to the 10 degrees C level. In carp the body clearance parameter (ClB(SDM)) was significantly higher at 20 degrees C compared to the value at 10 degrees C, whereas for trout this parameter was in the same order of magnitude for both temperatures. N4-acetylsulphadimidine (N4-SDM) was the main metabolite of SDM in both species at the two temperature levels. The relative N4-SDM plasma percentage in carp was significantly higher at 20 degrees C than at 10 degrees C, whereas there was in trout no significant difference. In neither species was the peak plasma concentration of N4-SDM (Cmax(N4-SDM)) significantly different at two temperatures. The corresponding peak time of this metabolite (Tmax(N4-SDM)) was significantly shorter at 20 degrees C compared to 10 degrees C in both carp and trout. In carp at both temperatures, acetylation occurs to a greater extent than hydroxylation. Only the 6-hydroxymethyl-metabolite (SCH2OH) was detected in carp, at a significant different level at the two temperatures. Concentrations of hydroxy metabolites in trout were at the detection level of the HPLC-method (0.02-micrograms/ml). The glucuronide metabolite (SOH-gluc.) was not detected in either species at the two temperatures.  相似文献   

5.
Paired incisions (n = 6 pairs) were made in the jejunum of each of 8 Holstein cows. Pairs consisted of 2-cm transverse incisions, 35 cm apart, at the antimesenteric region and at the mesenteric region. Bursting-wall tension was used to test mechanical strength, and cellular and vascular events of healing were evaluated using histologic examination and microangiography. Healing was evaluated at postoperative hour (POH) 48 in 4 of the cows (group 1) and at POH 96 in the remaining 4 (group 2). Evidence of leakage of intestinal contents was not found in any of the cows. At POH 48 and 96, bursting-wall tension was significantly (P less than 0.001) greater in the intestinal segments with antimesenteric incisions than in those segments with mesenteric incisions. Disruption of normal vasculature was seen at mesenteric and antimesenteric sites; ingrowth of vessels, reformation of vascular plexuses, and development of collateral circulation were observed at POH 96. Granulation tissue was observed at POH 96 at the antimesenteric and mesenteric sites, and early stages of mucosal reepithelialization were seen in several sections at POH 48. Better apposition of tissue layers was seen in antimesenteric incisions, but mucosal eversion was evident in several mesenteric incisions. Some sections examined from cows at POH 96 had complete bridging of mucosa, submucosa, and muscularis layers at the antimesenteric location. Inflammatory cells were observed along the incision and at the mucosal and serosal surfaces in many of the sections. Deposition of new collagen was not appreciable in any section at POH 48 or 96.  相似文献   

6.
Muscle growth was studied in larvae of sea bass, Dicentrarchus labrax L., reared at two temperatures: real ambient temperature ( congruent with 15 degrees C during vitelline phase and increased gradually) and 19 degrees C from fertilization until the end of larval development. Muscle cellularity, body length and body weight were measured. Early temperature influenced larval development and so, pre-larval phase finished earlier at 19 degrees C than at ambient temperature (4 and 6 days, respectively). Temperature also affected muscle growth such that at hatching and at mouth opening hypertrophy of muscle fibres was greater at 19 degrees C (P < 0.05), whereas hyperplasia was similar in both groups. After 25 days, the cross-sectional area of the white muscle was greater at 19 degrees C (P < 0.05), which was mainly associated with a higher proliferation of new white muscle fibres. At this stage the body length was also higher at 19 degrees C. Metamorphosis finished earlier in fish reared at 19 degrees C (52 days) than at natural temperature (82 days). At this developmental stage body length and cross-sectional area of the myotome were similar in both groups. However, muscle cellularity differed between groups. Thus, hypertrophy of muscle fibres was higher in fish reared at ambient temperature (P < 0.05), whereas proliferation of new muscle fibres was higher at 19 degrees C (P > 0.05).  相似文献   

7.
A fermentation process using Lactobacillus acidophilus added to edible food wastes was evaluated for its bactericidal action on selected gram-positive organisms. The Lactobacillus fermentation converts food wastes into an animal feed ingredient. In this study, 5 gram-positive bacteria of zoonotic importance were individually tested. These organisms were: Group E Streptococcus, Erysipelothrix rhusiopathiae, Clostridium perfringens, Corynebacterium pseudotuberculosis, and Listeria monocytogenes. For each experiment, Lactobacillus was first mixed into ground waste; one of the test organisms was then inoculated and mixed. This mixture was divided among eight 5.5-L containers and incubated (duplicates) at 5 C, 10 C, 20 C, and 30 C for 96 hours. Internal waste temperature, reduction-oxidation, and pH were monitored. Waste samples were taken initially and at subsequent 24-hour periods. Qualitative and quantitative recoveries of the test bacteria were attempted for each sample. Group E Streptococcus was reisolated in increasing numbers at all temperatures throughout the fermentation period. Erysipelothrix rhusiopathiae was recovered throughout the 96-hour period at 5 C; at 10 C it was recovered at 24 hours but not at 48 hours. Erysipelothrix rhusiopathiae was killed by 24 hours at 20 C and 30 C fermentation temperatures. Clostridium perfringens survived the entire test period at 5 C, 10 C, and 20 C; it was killed by 72 hours at 30 C. Neither Corynebacterium pseudotuberculosis nor Listeria monocytogenes was reisolated at any temperature at any time.  相似文献   

8.
王力  李凤霞  周万福  李晓东 《草业科学》2012,29(8):1256-1261
利用三江源两个不同海拔高度区牧业气象观测站1989-2010年高山嵩草(Kobresia pygmaea)物候观测资料及同期日、月、年气象资料,通过回归、相关和非参数检验方法,就青海省海拔相差较大的曲麻莱和河南的气候变化及其对高山嵩草物候的影响差异进行对比研究。结果显示,22年来两站年平均气温增速相当,高海拔区的平均最低气温增幅大于低海拔区,而高海拔区的平均最高气温增幅小于低海拔区,生长季（4―9月）与全年的气温变化有相同趋势。两站全年及生长季气温变化均显著相关,其差异主要受海拔影响。两站高山嵩草的返青期、黄枯期和生长季均存在明显的年际波动,高海拔区的波动大于低海拔区。海拔每升高100 m,高山嵩草的返青期推迟3.3 d,生长期缩短2.5 d。1989―1999年与2000―2010年两个时间段平均物候期高海拔区提前6~25 d,生长期延长3 d。低海拔区返青期提前1 d,其余物候期推迟1~9 d,生长期延长6 d。高海拔区高山嵩草的生长更容易受气候变化的影响,其生境更为脆弱。  相似文献   

9.
S H Kleven 《Avian diseases》1985,29(4):1266-1268
The stability of the F strain of Mycoplasma gallisepticum was determined in reconstituted powdered skim milk, phosphate-buffered saline, tryptose phosphate broth, and distilled water at 4, 22, and 37 C. The culture was stable for up to 24 hr in all diluents at 4 and 22 C. At 37 C, the culture was stable up to 24 hr in phosphate-buffered saline, but there was a slight reduction of viability in tryptose phosphate broth at 8 and 24 hr, and the titer was reduced in skim milk at 24 hr. In distilled water, the culture was stable up to 4 hr at 37 C. A reduced titer was observed after 8 hr, and at 24 hr the culture was no longer viable.  相似文献   

10.
通过奶牛生产性能（dairy herd improvement,DHI）测定体细胞数,探究奶牛的胎次及其不同泌乳阶段对其乳体细胞数（somatic cell count,SCC）和乳损失量的影响。通过对某养殖场泌乳期奶牛DHI的测定进行分析,结果表明：体细胞评分（somatic cell score,SCS）随奶牛胎次的增加而增加,但SCS在不同胎次的不同泌乳阶段表现有所不同。一胎牛SCS随着泌乳期的延长而增加,前期、中期与后期的SCS呈显著性差异（P＜0.05）;二胎牛与三胎牛SCS呈现相同变化规律,泌乳前期的SCS较泌乳中期高,而泌乳后期SCS显著高于前2个泌乳阶段（P＜0.05）。乳损失量随胎次的增加整体呈现增加趋势,且泌乳早期和泌乳后期乳损失量高于泌乳中期。  相似文献   

11.
The serum salicylate concentration produced by oral administration of plain aspirin and several aspirin-containing products given at 8-hour intervals for 7 treatments was measured in 36 laboratory-conditioned adult dogs. The dogs were randomly allotted to 6 groups of 6 dogs each: group 1 was given plain aspirin at a dosage of 25 mg/kg of body weight: group 2 was given plain aspirin at a dosage of 10 mg/kg; group 3 was given buffered aspirin at a dosage of 25 mg/kg; group 4 was given enteric-coated aspirin at a dosage of 25 mg/kg; group 5 was given buffered aspirin at a dosage of 25 mg/kg; and, group 6 was given a placebo. Serum salicylate concentration was measured at 2-hour intervals for the first 8 hours, and then at 8-hour intervals for the next 40 hours. Following the last dosing, serum salicylate concentration was measured at 2-hour intervals until 56 hours; the final 2 samples were measured at 64 and 72 hours. The effect of aspirin on the gastric mucosa was studied in 12 dogs, 3 each randomly selected from groups 1, 3, 4, and 5. The gastric mucosa of each dog was examined with a fiberoptic gastroscope 3 days before the beginning of treatment; lesions were not seen. The drugs were administered as described and the gastric mucosa of each dog was reexamined at 72 hours. Administration of the aspirin-containing products at 8-hour intervals resulted in sustained therapeutic serum salicylate concentrations (greater than 5 mg/dl) in all dogs, except those of group 2. The greatest fluctuation in serum salicylate concentration was found in dogs of group 4. Gastric lesions were seen only in the 3 dogs of group 1.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

12.
在青藏高原东部的一个高山坡面上,沿着海拔设置高、中、低3个海拔部位,并在高、低海拔之间进行暗紫贝母植株的对换移植实验,然后测定各部位的生态因子、暗紫贝母植株花、果实和种子的特征。结果表明,1)生态因子中积雪融化时间、气温及土壤含水量在各海拔之间有明显的差异;2)花部特征中花被片的长度和宽度,雄蕊花药和花丝的长度,花柱和柱头裂片的长度都是高海拔部位最长,低海拔部位最短;3)对花生物量来说,高海拔部位比低海拔部位大39.4%;从花与地上部分二者生物量的比率来看,高海拔部位比低海拔部位大12.3%,两个指标都是高海拔部位排名第一;4)单粒果实重以低海拔部位最重,达到1282 mg,比高海拔部位大48.3%;5)单粒果实种子数以高海拔部位最少,比低海拔部位少了38.1%;6)高海拔部位的种子百粒重达到142.3 mg,而低海拔部位种子百粒重只有94.6 mg。移植实验进一步验证了上述的测定结果,这说明暗紫贝母繁殖器官确实要受海拔的影响,而且主要跟海拔梯度上的融雪时间、气温(尤其是零下低温)、紫外线强度、访花昆虫等有关。  相似文献   

13.
The pupal duration of Rhinoestrus purpureus was studied under variable degrees of temperature and relative humidity (RH). It was found that pupal duration was affected by temperature but not by RH. An increase in the temperature above 22 degrees C decreased the pupal duration: 26-27 days at 22 degrees C, 16-24 days at 27 degrees C, 13-15 days at 32 degrees C. At 37 degrees C, the pupated larvae failed to pupate and died. The deformity ratio of emerged flies was 25-30% at 22-32 degrees C, but it was directly proportional to RH at a constant temperature of 32 degrees C: 26.1% at 75% RH, 16.7% at 50% RH, 6.7% at 30% RH. It was concluded that the optimum temperature and RH for obtaining normal active flies were 32 degrees C and 30%, respectively.  相似文献   

14.
A study was initiated to (1) determine species of gastrointestinal nematodes present in cattle in selected areas of Oregon, (2) examine seasonal abundance of these nematodes as an indicator of periods of transmission, and (3) determine when developmental inhibition occurs in the major genera of nematodes encountered. Four study sites were chosen: Corvallis, Langlois, near Fort Rock, and southeast of Klamath Falls on the Oregon-California border. Eight sets of three to four tracer calves each were introduced onto pasture at each site over a 2 year period with time of turn out onto pasture corresponding to late spring, mid-summer, late fall and late winter. At Corvallis, a distinct seasonality in parasite transmission was evident, peaking during the fall and winter. At Langlois, transmission was fairly constant throughout the year. No discernible patterns were evident at either Klamath Falls or Fort Rock. Eight nematode genera were found during the study. Ostertagia, Cooperia, Nematodirus and Trichostrongylus were present at all study sites and were the most common genera at each. Trichuris was found at all sites except Klamath Falls. Oesophagostomum was present in tracers only from Langlois and Corvallis while Haemonchus was found only at Klamath Falls and Fort Rock. Capillaria was only present at Klamath Falls. Where possible, specific transmission patterns for Nematodirus, Cooperia, and Ostertagia were determined for each site. Nematodirus was transmitted fairly steadily at both Langlois and Corvallis but was quite variable at Fort Rock. Developmental arrest was detected in this genus at all study sites during the fall and/or winter. Cooperia exhibited the most seasonally defined pattern of transmission, peaking during the fall and winter at Langlois, Corvallis and Klamath Falls. Hypobiotic larvae of Cooperia were present during the fall and/or winter only at Langlois and Corvallis. Peak transmission of Ostertagia at Langlois and Corvallis occurred during the fall and winter. At Fort Rock, transmission was lowest in the fall and increased in the winter. Hypobiotic larvae were evident in the fall and winter at Corvallis, Fort Rock and Klamath Falls. These data suggest Type II ostertagiasis may occur in late winter through spring in these areas. Hypobiotic larvae of Ostertagia were not detected at Langlois. The lack of appropriate environmental stimuli is one possible explanation for the apparent lack of hypobiosis at that site.  相似文献   

15.
[目的]为了提高云南黄牛的生产性能,优选主要的杂交改良父本,开展云南黄牛杂交改良。[方法]用西门塔尔牛、短角牛、安格斯牛、海福特牛等分别与云南黄牛母本杂交,测定不同杂交组合后代初生、6月龄、12月龄、24月龄的体重体尺。[结果]云南黄牛经过杂交改良后,改良效果良好,杂交后代对云南高原的气候条件适应性良好。在农村饲养条件下,西×云杂一代牛初生重平均为24.57kg,6月龄体重平均为135.83kg,12月龄体重平均为196.21kg,24月龄体重平均为344.24kg,分别比本地黄牛提高74.13%,59.20%,56.53%和78.10%。短×云杂交一代牛初生重平均为22.28kg,6月龄体重平均为117.20kg,12月龄体重平均为193.56kg,24月龄体重平均为314.86kg,分别比本地黄牛提高57.90%,38.10%,54.21%和62.90%;安×云杂交一代牛犊牛初生重平均为21.21kg,6月龄体重平均为134.34kg,12月龄体重平均为196.18kg,24月龄体重平均为268.45kg,分别比本地黄牛提高50.32%,57.45%,56.51%和38.89%;海×云杂交一代牛初生重平均为22.78kg,6月龄体重平均为124.97kg,12月龄体重平均为190.52kg,24月龄体重平均为289.50kg,分别比本地黄牛提高61.45%,46.47%,51.99%和49.78%。[结论]西×云杂一代牛、短×云杂交一代牛、安×云杂交一代牛和海×云杂交一代牛生产性能显著提高,效益明显。  相似文献   

16.
The reproductive tracts of 22 Friesian dairy cows were examined from seven to 35 days after insemination using a real time B-mode ultrasound scanner with a 7.5 MHz transducer. The earliest detection of pregnancy was at nine days when a vesicle was imaged within the lumen of the uterine horn. The early conceptus was seen at day 13 within the vesicle and these structures were followed ultrasonically until day 35. There was a sudden enlargement of the vesicle at day 19 and a heart beat was detected in the embryo at day 22. The allantois was imaged at day 23 and the amnion by day 29. The embryonic outline was clearly defined by day 33 when the body cavities could be discerned. This ability to determine pregnancy at an early stage should prove to be a useful technique in investigating the problems associated with early embryonic death in cattle.  相似文献   

17.
通过对鸡感染柔嫩艾美耳球虫时盲肠中常见正常厌氧微生物的变化情况进行检测研究发现:鸡在感染球虫后第7、10、14天时盲肠中类杆菌(Bacteriodes)的数量显著减少(P<005),而梭状芽孢杆菌(Clostridium)则显著增多;在球虫感染后的第7、10天时,盲肠中的消化球菌(Peptostreptocuccus)和真杆菌(Eubacterium)呈显著下降(P<005)。上述结果从一个方面阐明了柔嫩艾美耳球虫感染导致对某些其它感染抵抗力下降的机制。  相似文献   

18.
黄土丘陵区不同立地条件下紫花苜蓿地土壤水分动态变化   总被引：4，自引：0，他引：4  
研究了定西市安家沟流域不同立地条件紫花苜蓿Medicago sativa土壤水分的变化。结果表明：阳坡土壤水分均小于阴坡土壤水分,紫花苜蓿在不同立地条件下土壤水分都发生了显著的变化,但其顺序为阴坡台地>阴坡坡地>阳坡台地>阳坡坡地。不同立地类型各土壤层次的月变化存在显著差异,阴坡台地和阴坡坡地第1茬（4-6月）的土壤水分极显著高于阳坡台地和阳坡坡地的土壤水分,二者间没有显著差异,而在7月后,阴坡台地极显著高于其他立地条件的土壤水分。不同立地条件下紫花苜蓿每层深度土层的土壤水分都发生了不同程度的变化,在整个垂直剖面上都在降低,40～100 cm土层土壤水分降低最多。  相似文献   

19.
The objective of this study was to evaluate the effect of oxidation on mu- and m-calpain activity at varying pH and ionic strength conditions in the presence of calpastatin. In 2 separate experiments, purified porcine skeletal muscle mu- or m-calpain (0.45 units of caseinolytic activity) was incubated in the presence of calpastatin (0, 0.15, or 0.30 units) at pH 7.5, 6.5, or 6.0 with either 165 or 295 mM NaCl. The reactions were initiated with the addition of CaCl2 (100 microM for mu-calpain; 1 mM for m-calpain). In Experiment 1, mu- or m-calpain was incubated with the calpain substrate Suc-Leu-Leu-Val-Tyr-AMC (170 microM). Either 0 or 16 mu microM H2O2 was added to each assay. Activity was measured at 60 min. In Experiment 2, calpain was incubated with highly purified porcine myofibrils (4 mg/mL) under conditions described. Either 0 or 100 microM H2O2 was added immediately prior to the addition of calpain. Degradation of desmin was determined on samples collected at 2, 15, 60, and 120 min. Results from Experiment 1 indicated that oxidation decreased (P < 0.01) activity of mu-calpain. Mu-calpain had the greatest (P < 0.01) activity at pH 6.5, and m-calpain had the greatest (P < 0.01) activity at pH 7.5 at 60 min. m-Calpain activity was not detected at pH 6.0. Mu- and m-calpain activity were lower (P < 0.01) at 295 mM NaCl than at 165 mM NaCl at all pH conditions. Oxidation lowered (P < 0.01) calpastatin inhibition of mu-and m-calpain at all pH and ionic strength combinations. In Experiment 2, oxidation decreased proteolytic activity of mu-calpain against desmin at pH 6.0 (P < 0.05 at 15, 60, and 120 min) and decreased m-calpain at all pH conditions. However, desmin degradation by mu-calpain was not as efficiently inhibited by calpastatin at pH 7.5 and as at pH 6.5 (P = 0.03 at 60 min) when oxidizing conditions were created. This is consistent with the results from Experiment 1, which indicated that oxidation decreased the ability of calpastatin to inhibit mu-calpain. These studies provide evidence that oxidation influences calpain activity and inhibition of calpains by calpastatin differently under varying environmental conditions. The results suggest that, at the higher pH conditions used, calpastatin may limit the possibility of oxidation-induced inactivation of mu-calpain.  相似文献   

20.
The macrolytic lactone F28249-alpha was titrated in experimentally infected sheep and found to be highly effective against most of the common gastrointestinal nematodes as a single oral dose, given at a rate of 0.025, 0.05, or 0.1 mg/kg. Specifically, maximal activity was evident at even the lowest dosage against adult Haemonchus contortus, Ostertagia circumcinta, Trichostrongylus axei, and T colubriformis and L4 O circumcinta. Activity against Oesophagostomum columbianum was also high at all dosages, with a calculated ED95 of 0.029 mg/kg. Cooperia curticei was eliminated at 0.1 mg/kg, but control was erratic at the lower dosages. The greatest weakness of this compound was its activity against C oncophora. The activity against this parasite was weak (less than or equal to 85%) at all dosages, and the dosage-response curve was flat, suggesting dosages substantially higher than those given would be necessary for high-order control of this species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号