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1.
In semi-arid Mediterranean areas, small grain aftermath stubble represents an important summer source of food for grazing flocks of small ruminants. Wheat stubble is a mediocre source of forage and flocks are grazed in summer under harsh conditions of temperature and air dustiness. However, stubble grazing procedures are changing, water and shading are more frequently available between grazing sessions (“improved management”), and the biological soundness of this ancestral practice needs to be re-visited. The present study was aimed at evaluating the cost in energy of “improved” wheat stubble grazing, compared with feeding a similar diet indoors. The intake of stubble was first quantitatively and qualitatively evaluated in Awassi sheep. Ewes consumed daily 980 ± 100 g day− 1 of wheat stubble. Ewes were then housed and fed diets consisting of wheat hay, straw and grain formulated to be iso-energetic and iso-nitrogenous to diets consumed from wheat stubble. The average intake of ME was similar during the confinement and the pasture periods (6.4 ± 0.5 and 7.6 ± 0.8 MJ day− 1of ME, respectively). During 2 days of each period, animals were fitted with external electrodes and data loggers of heart rate and skin temperature. Energy expenditure (EE) was calculated from oxygen consumption estimated as the product of heart beats rate measured for the two days by the amount of oxygen delivered to body tissues at each heart beat (O2 pulse). The O2 pulse was determined by simultaneously measurement of oxygen consumption and HR twice daily on two occasions, while grazing stubble and indoors. Energy expenditure and energy balance were not different in sheep while grazing wheat stubble (11.1 and − 3.5 MJ day− 1) or fed indoors (11.1 and − 4.8 MJ day− 1). Our data show that stubble did not cover nitrogen and energy requirements for maintenance, and that the cost of summer stubble grazing carried out under conditions described here is less than thought before.  相似文献   

2.
The chemoprophylactic effects of paromomycin sulfate against natural cryptosporidiosis in young kids were investigated. Two studies were carried out using two groups of 18 and 12 animals in two pens. In each pen, kids were allocated to treated or control groups. The treatment consisted of oral paromomycin given at 100 mg kg−1 body weight day−1 for 11 consecutive days from 2 days of age. All kids were weighed at 2, 6 and 10 days of age. Infection was monitored by collecting fecal samples and staining fecal smears every 3–4 days from days 4 or 5 to days 15 or 19. The results clearly showed the efficacy of paromomycin in reducing cryptosporidial oocyst output. Moreover, paromomycin prevented clinical signs and mortality.  相似文献   

3.
The effectiveness of Duddingtonia flagrans in reducing the free living third stage larvae (L(3)) of equine cyathostomes on pasture when fed to horses has been demonstrated in cold temperate climates. The objective of this experiment was to assess the efficacy of D. flagrans against equine cyathostomes in the subtropical environment of southern Louisiana. Fecal pats were prepared by mixing feces obtained from a parasite-free horse fed D. flagrans at a dose of approximately 2 x 10(6) spores kg(-1), with feces containing cyathostome eggs from a parasitized horse. Control pats contained feces from a parasite-free horse mixed with feces containing cyathostome eggs. The fecal pats were placed on pasture in six replicates at 4-week intervals from March 1997 until January 1998. Comparison of recoveries of L(3) from non-treated control pats in the field with non-treated coprocultures maintained in the laboratory indicated that L(3) survival on pasture was reduced during the months of May, June, July, August and September. The efficacy of the fungus was determined by L(3) recovery from grass surrounding the fecal pats of treated and control groups. D. flagrans significantly reduced L(3) during the months of April, May, and October 1997 to January 1998 (range 66-99% reduction, p=0.0001), and for the year as a whole (p=0.0001).  相似文献   

4.
Faecal pats containing parasitic nematode eggs were deposited monthly on worm-free pasture, from mid-1975 to early in 1979, near Rockhampton in central Queensland. Pasture samples were collected monthly from beside these pats and the number of infective larvae on the samples was counted.

Cooperia spp. were the most numerous larvae on pasture all year round and Haemonchus placei were commonly present in low numbers. Small numbers of Oesophagostonum radiatum larvae were found, mostly during summer.

Dung beetle activity and rainfall influenced larval populations on pasture, but temperature did not. Beetles were not active in winter, and pats deposited in spring, summer and autumn when beetles were active yielded only 42, 44 and 26%, respectively, as many larvae per 1000 eggs deposited as winter pats. Pats in which beetle activity was minimal (feeding only), moderate and intense (complete destruction), yielded 43, 10 and 6%, respectively, as many larvae per 1000 eggs as intact pats.

Larval densities on pasture were highest after the first saturating rains during the spring-summer period and most of these larvae migrated from unattacked pats deposited in winter. Beetle numbers and activity increased with the summer rains and so few larvae were available to migrate onto pasture during late summer and autumn when the highest falls of rain were recorded. The regression of larval recovery on rainfall was positive and statistically significant when data collected soon after these very heavy rainfall periods were omitted from the analysis.

In 1977, drought-breaking rains increased the normal larval density on pasture 10-fold because larvae in pats deposited in the last 4 months of the drought migrated onto pasture immediately after the rains.

This work suggests that in summer rainfall areas where dung beetles are active, helminth control may be achieved by reducing the worm egg output from cattle during the winter.  相似文献   


5.
Cross-bred goats in Burundi infested with gastrointestinal nematodes were submitted to fecal investigations and injected subcutaneously with ivermectin. In Experiment 1, goats were treated with 200 μg kg−1 bw ivermectin. In Experiment 2, animals were administered twice that dose. In Experiment 3, goats suspected to be resistant to other anthelmintics were treated with 200 μg kg−1 bw ivermectin. In Experiment 4, two doses of the same strength were injected with an interval of 7 days. Results demonstrate that 200 μg kg−1 bw ivermectin is effective for the control of gastrointestinal nematodes of goats in Burundi; this dosage is also effective against nematodes suspected to be resistant to other anthelmintics. The administration of 400 μg kg−1 bw did not induce greater or more prolonged effectiveness percentages. The supposed decrease of ivermectin's residual activity on Day 28 might be avoided by administering two doses with an interval of 7 days. No adverse effects were observed in treated animals.  相似文献   

6.
1,25（OH）2D3是维生素D的主要活性形式,影响人和动物脂肪形成,为探究其在猪脂肪细胞增殖分化中的作用,试验从3~5日龄仔猪皮下脂肪组织分离培养前体脂肪细胞,并以浓度为0、0.1、1、10、100和1 000 nmol/L的1,25（OH）2D3分别处理,在培养的0、1、2、4、6、8和10 d采用MTT比色法检测细胞增殖活性;在诱导分化后0、1、2、4、6、8和10 d,以油红O染色提取法和实时荧光定量PCR检测细胞成脂分化及分化标志基因过氧化物酶体增殖物激活受体γ（PPARγ）和脂肪酸合成酶（FAS）表达。结果显示,0.1和1 nmol/L 1,25（OH）2D3显著促进猪前体脂肪细胞增殖（P<0.05）,而浓度为10~100 nmol/L时则抑制细胞增殖（P<0.05）;0.1和1 nmol/L 1,25（OH）2D3显著抑制猪前体脂肪细胞分化（P<0.05）,降低PPARγ和FAS mRNA表达水平（P<0.05）,但在浓度为10和100 nmol/L时,显著促进猪前体脂肪细胞分化（P<0.05）,上调PPARγ和FAS mRNA表达（P<0.05）;浓度达1 000 nmol/L时,可能对细胞有毒性作用。综合以上结果,低浓度1,25（OH）2D3促进猪前体脂肪细胞增殖,而通过下调PPARγ表达抑制分化;高浓度1,25（OH）2D3抑制猪前体脂肪细胞增殖,通过上调PPARγ表达促进分化。1,25（OH）2D3对猪前体脂肪细胞增殖和分化具有双向作用。  相似文献   

7.
The effect of anthelmintic treatment on the growth and conception rate in beef heifers was studied in southwestern Virginia, USA. Forty mixed-breed heifers were divided into two groups at weaning and placed on experimental pastures. Control heifers did not receive anthelmintic treatment, while animals in the treatment group were given ivermectin (200 μg kg−) at the time of allocation to groups in October and again in April the following year. Supplemental feed was provided throughout the winter to ensure adequate weight gains. In May, the heifers were exposed to bulls for natural breeding for a period of 6 weeks. Weight gains, fecal egg counts, serum pepsinogen levels and pasture larvae counts were monitored throughout the experiment. No difference in conception rate was observed between the two groups, although the cumulative weight gain was significantly greater in treated than non-treated animals. Serum pepsinogen levels and fecal egg counts were also generally lower in treated than non-treated heifers.  相似文献   

8.
The primary objective of this study was to determine the contribution of several management variables to average production per day of life (PPDL). A secondary objective was to compare PPDL between two geographic regions in North America and between dairy herds within the two regions. PPDL was determined for animals culled from four ‘large’ dairy farms in Florida, USA (FL), and eight ‘small’ dairy farms in Prince Edward Island, Canada (PEI). Average milk PPDL was calculated by summing the kilograms of milk produced per cow and dividing by the total number of days from birth until culling. PPDL for the four FL herds (9.50 kg day−1) was significantly higher than PPDL for the eight PEI herds (8.64 kg day−1). PPDL increased in a quadratic fashion with number of lactations. PPDL did not differ between the eight PEI herds. Significant differences in PPDL were identified between the four FL dairy farms.

The regression of PPDL on average lactational milk yield (AVGFCM), number of lactations (LACT), age at first calving and average days to conception explained 94.5% and 92.4% of the variation of PPDL for multiparous cows in the PEI and FL herds, respectively. One variable (AVGFCM) accounted for 68% and 55% of the variance in PPDL for PEI and FL, respectively. The addition of LACT to the model explained 87% and 81% of the variance in PPDL for PEI and FL, respectively.  相似文献   


9.
During the 1997 Swedish grazing season, faeces were collected every 3 weeks on 7 occasions from young grazing cattle with moderate nematode parasite infections. From this source 12, 400 g dung pats were set up on each sampling occasion on a specially designated area of pasture. Half of these pats were placed on pasture where it was aimed to prevent snow cover during the subsequent winter. During the grazing season, herbage growth was kept at reasonably uniform height by clipping and the dung pats were protected from destruction by animals and birds. At the time of animal turn-out the following year (7th April 1998), it was observed that all dung pats had disappeared. Assessments of the survival of infective larvae, both on pasture and in soil, were made in a circular area encompassing the location of each pat. These sampling procedures were completed within a 3 week period. All faecal deposits yielded infective larvae at turn-out the following year, with proportionally greater numbers developing from nematode eggs deposited in cattle dung during the mid third of the previous grazing season. The surface layer of soil was found to be an important reservoir for infective larvae, with numbers recovered being approximately half those found in the overlying pasture samples. No significant differences were found between the normal pasture and snow excluded pasture in the number of infective larvae recovered from both pasture and soil samples. The epidemiological consequences of these findings are discussed.  相似文献   

10.
We explored the applicability of the 13C bicarbonate dilution technique for determination of energy expenditure (EE) in young bulls in comparison to whole body indirect calorimetry (IC). Twelve bulls of a F2 German Holstein x Charolais cross (4.5 months, 332 ± 16 kg BM) received a diet providing 1000 kJ ME d− 1 kg BM− 0.75 and 4.3 g crude protein d− 1 kg BM− 0.75. Bulls were housed in respiration chambers and received an intravenous bolus of NaH13CO3 (A: 3 μmol kg BM− 1 (n = 2), B: 7 μmol kg BM− 1 (n = 4), C: 17.5 μmol kg BM− 1 (n = 6), 99 at.% 13C) into the jugular vein to measure EE. Simultaneously, EE was determined by IC. After the 13C administration blood samples and breath gas were collected from the animals in the respiration chamber during a 24-h period (7.00–7.00 h). The recovery of 13C in breath CO2 (% of 13C dose) was irrespective of NaH13CO3 dose (A: 69.7 ± 2.7%, B: 70.5 ± 4.5%, C: 75.0 ± 4.9%; P > 0.05). Only small amounts of 13C were excreted in urine (3.4 ± 2.6%) and feces (2.0 ± 1.3%). The EE determined by the 13C bicarbonate method using breath and blood 13C recovery rates as correction factors was not different from that measured by IC (816 ± 81 [blood] or 827 ± 101 [breath] vs. 820 ± 90 kJ d− 1 kg BM− 0.75). Bland–Altman analysis showed a 95% confidence interval for EE of ± 99 and ± 109 kJ d− 1 kg BM− 0.75 based on blood and breath 13C recovery, respectively. In conclusion, the 13C bicarbonate dilution method is appropriate to obtain reliable estimates of EE in young bulls using blood CO2 or breath CO2 under standardized experimental conditions, i.e. in the fasting state.  相似文献   

11.
Three experiments were performed to study effects of decreased concentrations of estradiol-17β (E2) on lifespan and function of ensuing ovine corpora lutea (CL). In experiment 1, 52 follicles were collected from 10 ewes and placed into individual culture with 0 or .01 μCi 3H-androstenedione (10 ng; 3H-A) and 0, 10−11, 10−9, 10−7, or 10−5 M of a nonsteroidal aromatase inhibitor, CGS16949A (CGS). Concentrations of E2 secreted into the medium, and synthesis of estrogens as estimated by formation of 3H-water from 3H-A were decreased by 10−5 and 10−7 (P<.01), but not 10−9 or 10−11 M CGS. In experiment 2, luteolysis was induced in 24 ewes by injection of PGF2 on days 5 to 10 of the estrous cycle (0 hr). Ewes received 0, 0.5, 1.0, 2.0 or 4.0 mg CGS per kg BW i.v. at −12, 0, 12 and 24 hr, and an ovulatory dose of hCG at 36 hr. Jugular (P<.001) and vena caval (P<.001) concentrations of E2 were decreased by CGS at all doses tested for 8 to 10 hr, but had returned to levels similar to control ewes by the time of the next injection. Concentrations of E2 around the time of the LH surge were similar in control and treated ewes. During the subsequent luteal phase, concentrations of progesterone (P4) were similar in control and treated ewes. Thus, transient decreases in E2 during the follicular phase were not deleterious to the subsequent luteal phase. In experiment 3, luteolysis was induced in 18 ewes by injection of PGF2 on days 6 or 7 (0 hr) of the estrous cycle. Ewes received 0 or 1 mg CGS per kg BW i.v. every 8 hr from 0 to 40 hr. Ovulation was induced with hCG at 36 hr. CGS reduced jugular (P<.001) and vena caval (P<.001) concentrations of E2, prevented an endogenous surge of LH (P<.05) and increased (P<.001) concentrations of FSH. All ewes had ovulated a marked follicle by 72 hr, but onset of the luteal phase, as assessed by concentrations of P4, was delayed (P<.01) in ewes receiving CGS. Delayed luteal phases were not solely attributable to the presence of new CL or to luteinization of follicular cysts. When data were aligned according to the day ewes were observed in estrus, profiles of P4 did not differ with treatment. Therefore, normal luteal function ensued following estrus whether or not ewes re-ovulated. In conclusion, decreased secretion of E2 by the preovulatory follicle was not involved in the ontogeny of CL of short lifespan or subnormal function. Instead, adequate production of E2 or precisely timed E2 secretion may be required during follicular development for subsequent functional luteinization.  相似文献   

12.
Molt induced by infusion of a gonadotropin-releasing hormone agonist (GnRH-A, ([D-leu6, Pro9]-GnRH N-ethylamide]) or feed withdrawal (FW) has been used as a model to study interactions between ovarian activity and thymosin β4 during molting in domestic hens. Thirty-three laying hens were divided into three groups: 1, controls, 2, GnRH-A infusion induced molt (GnRH-A), or 3, FW induced molt. All groups had reduced daylength. Blood was sampled weekly and assayed for concentrations of thymosin β4 and progesterone (P4). Plasma P4 concentrations were significantly depressed in both treatment groups compared to controls, indicating ovarian regression. Plasma P4 concentrations had returned to control values in the GnRH-A group by 28 d after the start of treatment, while P4 was still depressed in the FW group at day 42 when the experiment ended. Plasma concentrations of thymosinβ4 were elevated relative to controls from day 7 through day 14 in the GnRH-A group and from day 7 until day 28 in the FW group. It is concluded that plasma concentrations of thymosin β4 are elevated during molting in domestic hens, but the elevation is not attributable to depressed P4 concentrations.  相似文献   

13.
The effect of pituitary adenylate cyclase-activating polypeptide (PACAP) on growth hormone (GH) release was compared with that of prostaglandin E2 (PGE2) and growth hormone releasing factor (GRF) from cultured bovine anterior pituitary cells in vitro. Both PACAP and PGE2 stimulated GH release at concentrations as low as 10−9 and 10−8 M, respectively, (P<0.01). However, GRF released GH at a concentration as low as 10−13 M (P<0.01). Percent increases of GH compared with controls were not significantly different among GRF, PACAP, and PGE2 at 10−7 M; however, the increases of GH by the 10−8 M GRF, PACAP and PGE2 were 196, 118, and 27%, respectively, (P<0.01), and 124, 65, and 1% in the 10−9 M media, respectively, (P<0.01). When GRF and somatostatin (SS) were added together, the GH releasing effect of GRF was blunted (P<0.01). Similar bluntness were observed in PACAP and PGE2, when SS was added. The stimulatory effects of GRF and PGE2 together were similar to that by either GRF or PGE2 alone. When GRF and PACAP were added together, the GH released by both secretagogues was greater than that by PACAP alone (P<0.01); however, a synergistic effect was not clear when compared with GRF alone.

These findings suggest that PACAP and PGE2 may modulate the release of GH in cattle.  相似文献   


14.
在紫花苜蓿混播草地放牧利用过程中,由于家畜行为对分区位置和放牧阶段的适应机制尚不清晰,制约了混播草地的科学利用和高效转化。本文研究了苜蓿混播草地分区位置和放牧阶段对绵羊活动距离和活动时间的影响。结果表明：放牧分区位置距离饮水点和休息区的距离每增加100 m,绵羊的活动距离增加2.42 km·d-1,活动时间增加46.74 min·d-1。不同放牧阶段草地质量差异明显,绵羊的活动距离和活动时间随着放牧阶段,即进入放牧分区后的天数增加而显著增加。绵羊通过改变活动距离和活动时间适应放牧分区位置和放牧阶段草地质量的变化,增加活动速率来适应草地质量的降低。苜蓿混播草地集约化放牧育肥时,饮水点和休息区距离放牧分区最远端的距离不宜超过198 m,每个分区放牧时间不宜超过4 d。研究结果可为苜蓿混播草地肉羊高效放牧育肥提供技术支撑。  相似文献   

15.
A model for the prediction of bluetongue virus seroconversion was developed using weather variables and results from serum samples collected from a research herd of Hereford, Angus, Holstein and mixed breed beef cows at 12 different times over 2 years. The six weather variables analyzed were: mean daily air temperature; mean daily soil temperature at a depth of 10 cm; mean daily hours of wet vegetation; total days of rainfall ≥ 0.13 cm; total rainfall for each 7 day period; mean daily solar energy (W m−2). A maximum R2 multiple linear regression technique was applied to meteorological data collected during the four weekly intervals prior to each sample collection date (48 sets of weekly meteorological data). The best predictors for seroconversion were mean daily hours of wet vegetation and total rain days during the second weekly period prior to sample collection. The bluetongue virus seroconversion was related to mean daily hours of wet vegetation, total rain days, and total precipitation as expressed by the equation: Seroconversion=7.1+4.0 (mean daily hours of wet vegetation)−1.3 (total precipitation) (R2=0.62, P<0.0001).  相似文献   

16.
This study investigated the productive adaptability of pig breeds under different smallholder production conditions in Vietnam, comparing an indigenous with a Vietnamese improved breed. Fieldwork was conducted in four villages with different remoteness in North Vietnam from 2001 to 2002, in 64 households keeping the improved Mong Cai or indigenous Ban as sow breeds and progeny for fattening. Four visits per farm yielded 234 structured interviews. Reproductive performances were derived from 135 litters. Individual weights of pigs (n = 755) were obtained. Data were analysed by regression, linear and generalised linear, especially loglinear models.

Two distinct pig production systems were identified, that differed in remoteness, market access, resource availability, distribution of pig breeds and pig production intensity. Higher performances of 1.4 and 1.5 litters year− 1, 8.4 and 8.4 piglets weaned litter− 1, 66.6 and 93.0 kg piglets weaned sow− 1 year− 1, and 136 and 177 g day− 1 ADG were found in two villages near town with semi-intensive production conditions and a high rate of improved Mong Cai sows and MC and LW × MC offspring in the observed population. Lower performances of 1.1 and 1.1 litters year− 1, 4.6 and 5.5 piglets weaned litter− 1, 20.5 and 30.9 kg piglets weaned sow− 1 year− 1, and 66 and 85 g day− 1 ADG were observed in parallel to higher incidences of indigenous Ban pigs away from town under extensive conditions. Total live weight offtake per household per year was higher near town and in one village distant to town. MC and LW × MC remained even under demand-driven conditions below the performance potential reported for improved genotypes. Under resource-driven conditions with a saving-oriented production pattern, the higher-yielding but more demanding Mong Cai might not be an efficient production alternative as a further performance reduction can be assumed. A considerable live weight output was observed under resource-driven conditions and with a higher percentage of crossbred LW × Ban offspring in the population, possibly representing a promising production alternative. Factors influencing the performance expression of pigs, and the suitability of different methods for the assessment of performance parameters on-farm are discussed.  相似文献   


17.
(1)绵羊个体增重与放牧率呈线性负相关,个体最大增重临界放牧率,因季节不同而变化,随着个体增重与放牧率回归系数b绝对值的增大而降低,以始、终放牧期间所得临界放牧率最小,(2.04羊/hm2)。(2)公顷增重与放牧率的关系符合二次曲线,在达到公顷最大增重以前,随着放牧率的增大而增大,之后则随着放牧率的增大而下降,平均543羊/hm2。(3)公顷最大增重并不一定获取公顷最大利润,主要视买卖价格及其差值而定。(4)以冷蒿小禾草为主的退化草原,宜以个体最大增重的适宜放牧率作为管理标准,以使该类草原在利用中得以恢复。  相似文献   

18.
A 4-year study on the free-living stages of cattle gastrointestinal nematodes was conducted to determine (a) the development time from egg to infective larvae (L3) inside the faecal pats, (b) the pasture infectivity levels over time, and (c) the survival of L3 on pasture. Naturally infected calves were allowed to contaminate 16 plots on monthly basis. Weekly monitoring of eggs per gram of faeces (epg) values and faecal cultures from these animals provided data for the contamination patterns and the relative nematode population composition. At the same time, faecal pats were shaped and deposited monthly onto herbage and sampled weekly to determine the development time from egg to L3. Herbage samples were collected fortnightly over a 16-month period after deposition to evaluate the pasture larval infectivity and survival of L3 over time. The development time from egg to L3 was 1-2 weeks in summer, 3-5 weeks in autumn, 4-6 weeks in winter, and 1-4 weeks in spring. The levels of contamination and pasture infectivity showed a clear seasonality during autumn-winter and spring, whilst a high mortality of larvae on pasture occurred in summer. Ostertagia spp., Cooperia spp. and Trichostrongylus spp. were predominant and a survival of L3 on pasture over a 1-year period was recorded in this study.  相似文献   

19.
In an attempt to define the nature of the response of cattle to ephemeral fever infection, a number of indicators of inflammation were monitored during clinical disease. The total Ca, Zn, Fe, Cu, glucose and phosphate in plasma, together with blood ammonia, were assayed relative to changes in the rectal temperature. CaT levels fluctuated markedly and hypocalcaemia occurred in 4 of 8 cattle. Plasma Zn and Fe values fell while plasma Cu levels rose markedly in all cattle. Mean levels of serum NH3 of 20–30 μmol 1−1 rose to a peak value of 56 μmoll−1. Plasma glucose levels rose to a peak of 4.6 ± 0.5 mMl−1 and the plasma phosphate levels fell from 2.4 ± 0.1 mMl−1 to 1.17 ± 0.2 mMl−1 during fever. Values of pCO2 fell from a mean of 46.9 ± 3.6 mmHg to 36.4 ± 3.1 mmHg and coincided with a rise in pH. Virus was isolated 73 h (± 23) after inoculation and persisted until 130 h (± 21). The common role of these parameters in generalised inflammation and ephemeral fever is discussed.  相似文献   

20.
旨在研究口蹄疫病毒（foot-and-mouth disease virus,FMDV）结构蛋白VP1上的RGD（Arg-Gly-Asp）基序与宿主细胞表面受体整联蛋白的结合特异性,作者应用基于表面等离子共振技术（SPR）的Biacore 3000系统实时研究RGD基序分别与猪源整联蛋白αvβ6胞外区结构域、αv亚基胞外区结构域和β6亚基胞外区结构域的亲和力。首先通过结合试验筛选与RGD基序有结合的整联蛋白结构域,再对有结合的整联蛋白与RGD基序开展动力学分析。结果显示,合成的RGD基序与猪源整联蛋白αvβ6胞外区结构域有结合,结合动力学常数Ka、Kd、KD分别为42.3 M-1s-1、3.1×10-4s-1和7.33×10-6M;与整联蛋白αv亚基胞外区结构域之间亦有结合,结合动力学常数Ka、Kd、KD分别为21.8 M-1s-1、2.13×10-4s-1和9.79×10-5M;与β6亚基胞外区结构域几乎没有结合。综上表明,RGD与整联蛋白αvβ6胞外区结构域的结合比与整联蛋白αv亚基胞外区结构域之间的结合快且亲和力强。本研究将为进一步探讨FMDV与宿主细胞表面受体的相互作用提供参考。  相似文献   

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