The effects of birdsfoot trefoil (Lotus corniculatus) and chicory (Cichorium intybus) when compared with perennial ryegrass (Lolium perenne) on ovine gastrointestinal parasite development, survival and migration

Two experiments were conducted to investigate the effects of birdsfoot trefoil and chicory on parasitic nematode development, survival and migration when compared with perennial ryegrass. In experiment one, sheep faeces, containing 10,385 Cooperia curticei eggs were added to 25 cm diameter pots containing birdsfoot trefoil, chicory or ryegrass, and the pots maintained under optimal conditions for nematode parasite development. Replicate pots of each forage type were destructively sampled on day 8, 16, 20, 28 and 37 to collect the nematode larvae. When forages were compared on a dry matter basis, by day 16 there were 31% and 19% fewer larvae on birdsfoot trefoil and chicory than on ryegrass, respectively (P<0.01). In the second experiment, replicate 1m(2) field plots of birdsfoot trefoil, chicory and ryegrass were sub-sampled on day 14, 21, 35 and 49 for larval counts following the application of sheep faeces containing 585,000 Teladorsagia circumcincta eggs to each plot on day 0. Results showed there were a minimum of 58% and 63% fewer infective stage parasitic larvae on birdsfoot trefoil and chicory, respectively, compared with ryegrass on day 14 and 35 when forages were compared on a forage dry matter, plot area sampled and leaf area basis (P<0.01). Overall, these results indicate that the number of infective stage larvae on birdsfoot trefoil and chicory pasture was reduced by the effect of their sward structure on the development/survival/migration of ovine parasitic nematodes. These effects may be one of the ways in which these forages may affect parasitic infections in grazing livestock.     

Comparing relative feed value with degradation parameters of grass and legume forages

Relative feed value (RFV) was evaluated relative to in situ degradation parameters of grass and legume forages. Early-cut alfalfa (n = 20), late-cut alfalfa (n = 26), cool-season grass (n = 11), warm-season grass (n = 4), and grass-legume (n = 20) samples were collected from duplicate hay bales submitted to the 2002 and 2003 Missouri State Fair Hay Contests. Subsamples were incubated in the rumen of 2 lactating Holstein cows for 0, 6 or 8, 12, 24, and 48 h to determine in situ degradation of DM, ADF, NDF, CP, and hemicellulose over time. Degradation data were fit to a variety of candidate models to estimate degradation parameters. Correlation coefficients between degradation parameter estimates [sorted according to forage (early-cut alfalfa, late-cut alfalfa, grass, or grass-legume)] and RFV were determined. For further comparison, correlations between NDF degradation parameter estimates and digestible DMI were determined with data from a previous study. Degradation data were best fit to a single, gamma 2-distributed pool model without a lag phase. Relative feed value was significantly correlated (P < 0.05) with potentially digestible DM and CP for early-cut alfalfa, potentially digestible DM for late-cut alfalfa, and potentially digestible DM, NDF, and hemicellulose for grass-legume. The percentage of significant correlations (10.7%) across the entire data set was low and no correlations were significant for grass. Relative feed value did not account for the variation in degradation parameters, especially for grasses. A further correlation analysis, which compared digestible DMI with degradation parameter estimates reported from another data set, revealed that digestible DMI and degradation parameter estimates were related for grass but not for alfalfa forages. These results suggest that RFV is limited by its failure to include degradation parameters.     

Effects of gastrointestinal parasites on parasite burden, rectal temperature, and antibody titer responses to vaccination and infectious bovine rhinotracheitis virus challenge

Thirty-three colostrum-deprived Holstein bull calves (initial BW of 131 ± 4 kg) were used to determine the effect of timing of anthelmintic administration relative to vaccination on antibody titer response to vaccine component antigens. When calves were at least 3 mo of age, they were sorted randomly into individual pens and assigned to 1 of 3 treatment groups, treatments consisted of 1) dewormed 2 wk before vaccination (DPV), 2) dewormed at the time of vaccination (DV), or 3) control, vaccinated but not dewormed (CONT). All calves were inoculated with infective larvae of brown stomach worms (Ostertagia ostertagi) and intestinal worms (Cooperia spp.) on d 1, 7, 10, 14, and 18 for a total dose of 235,710 infective larvae per calf. Calves (DPV and DV) were dewormed on d 21 or 35 with a 10% fenbendazole suspension at 5 mg/kg of BW. On d 35, all calves were vaccinated with a modified-live virus respiratory vaccine containing IBRV (infectious bovine rhinotracheitis virus), BVDV-1 (bovine viral diarrhea virus genotype 1), BVDV-2 (BVDV genotype 2), PI-3 (parainfluenza-3), and BRSV (bovine respiratory syncytial virus). During the 103-d experiment, weekly fecal egg counts, blood, and rectal temperatures were collected and health status was recorded daily. Blood samples were obtained weekly to determine serum neutralizing (SN) antibody titers to IBRV, BVDV-1, BVDV-2, and PI-3 and cytokine levels for IL-4, IL-6, TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-gamma). There was a tendency (P < 0.09) for CONT calves to have greater IL-4 concentrations. By design, control calves had greater (P < 0.01) fecal egg counts during the experiment. All calves developed antibody titers to IBRV, BVDV-1, BVDV-2, and PI-3 by d 15 postvaccination. On d 88, all calves were challenged with IBRV and blood samples were obtained on d 88, 89, 90, 93, 95, 98, 99, and 103. All calves had increased rectal temperatures during the final 7 d of the IBRV challenge. However, the CONT group had greater (P < 0.01) rectal temperatures on each sampling day except d 90 compared with the DPV and DV treatments. Therefore, deworming before or at vaccination reduced parasite burden and decreased rectal temperature increase after an IBRV challenge. Deworming strategy had no effect on antibody response to vaccination or IBRV challenge.     

种草养畜的认知与实践

中国人多地少,且面临着人增地减的双重压力,人均粮食难以提高;我国粮食的生产能力,足以满足人们的口粮之需,缺口的是间接消费的粮食(饲料粮)和工业用粮。饲草生产营养素产量高于粮食生产,而草食动物是节粮型动物,种草养畜是解决我国饲料短缺的有效途径。实践证明,种草养畜具有节粮、高效、优质、安全和可持续的特点,是中国现阶段及未来畜牧业发展的重要战略之一。     

A survey of ovine parasite control practices in Tennessee.

A sample of 126 sheep producers in Tennessee was randomly selected from the members of a statewide organization of sheep producers. Data about the participants' farms, sheep, parasite control practices and sources of information regarding ovine parasite control were obtained by a telephone survey. The response rate was 99%. The typical respondent kept 20 lambs, 20 ewes and 2 rams on three pastures totalling 20 acres. In order of decreasing frequency, anthelmintics were given according to a regular schedule, to coincide with breeding management procedures, or to treat clinical signs of parasitism. Proportions of producers deworming the various classes of sheep zero, one, two, three, four or more than four times annually were as follows: lambs--3, 28, 40, 16, 9 and 8%, respectively; ewes--3, 8, 20, 16, 34 and 22%, respectively; rams--1, 9, 19, 15, 38 and 19%, respectively. The majority of respondents planned to deworm lambs (89%) and ewes (82%) the same number of times in the following year. Of the producers who dewormed sheep two or more times during 1989, 39-49% (ranges include different proportions for lambs, ewes and rams) used the same anthelmintic exclusively, and 51-61% used two or more drug classes. Of the owners using a single anthelmintic exclusively, most (39-66%) used ivermectin, followed by levamisole (19-33%) and benzimidazoles (13-24%). One hundred and three of 124 (83%) producers intended to use the same anthelmintics in the future. Sixty-four of 124 (52%) producers had discontinued using at least one ovine anthelmintic. The most common reasons for discontinuance were dissatisfaction with the clinical response after treatment and inconvenience of administration. Sheep-oriented publications, other sheep producers and veterinarians were considered the most important sources of information about deworming programs and choice of anthelmintics.     

Effects of supplemental feeding on gastrointestinal parasite infection in elk (Cervus elaphus): preliminary observations

The effects of management practices on the spread and impact of parasites and infectious diseases in wildlife and domestic animals are of increasing concern worldwide, particularly in cases where management of wild species can influence disease spill-over into domestic animals. In the Greater Yellowstone Ecosystem, USA, winter supplemental feeding of Rocky Mountain elk (Cervus elaphus) may enhance parasite and disease transmission by aggregating elk on feedgrounds. In this study, we tested the effect of supplemental feeding on gastrointestinal parasite infection in elk by comparing fecal egg/oocyst counts of fed and unfed elk. We collected fecal samples from fed and unfed elk at feedground and control sites from January to April 2006, and screened all samples for parasites. Six different parasite types were identified, and 48.7% of samples were infected with at least one parasite. Gastrointestinal (GI) nematodes (Nematoda: Strongylida), Trichuris spp., and coccidia were the most common parasites observed. For all three of these parasites, fecal egg/oocyst counts increased from January to April. Supplementally fed elk had significantly higher GI nematode egg counts than unfed elk in January and February, but significantly lower counts in April. These patterns suggest that supplemental feeding may both increase exposure and decrease susceptibility of elk to GI nematodes, resulting in differences in temporal patterns of egg shedding between fed and unfed elk.     

高寒山区6种多年生牧草生长发育特性研究

针对甘肃省临潭县高寒山区特殊的自然气候条件,于早春播种6种多年生牧草,以探讨其在高寒山区的生产性能及适应性。对其物候期、生物学特征、产量、营养及翌年越冬率观测结果表明:播种当年6种牧草均未完成其生活史,仅停留在分蘖(枝)期;甘肃红豆草、小冠花、甘农一号苜蓿和猫尾草产草量较高、适应性强、营养价值高,可在高寒山区退牧还草和人工草地中建植;垂穗披碱草适应性强,产草量较低,可作为改良退化草地草种加以利用;红三叶在高寒山区越冬率和产量都较低,在没有保护措施的情况下不建议种植。     

Growth and development of the ovine conceptus

This study was designed to characterize development of the ovine conceptus throughout gestation to establish the temporal relationships in metabolites, electrolytes, fluid volumes within the placenta, and hormonal changes with fetal growth. Length and weight of placentae, weight of cotyledons, and uterine weight increased between d 25 and 80 of gestation in advance of increases in fetal growth between d 80 and 140 of gestation. Allantoic fluid volumes changed (P < 0.01) between d 25 (21 mL) and 40 (91 mL), decreased to d 70 (32 mL), and then increased to d 140 (438 mL). Concentrations and total amounts of proteins in allantoic fluid were reduced between d 25 and 50, but total protein increased (P < 0.01) from d 40 (63 mg) to d 140 (2,991 mg). Concentrations of fructose in allantoic fluid varied between 2 and 6 mg/mL throughout gestation, but total fructose increased (P < 0.01) between d 25 (46 mg) and d 120 (679 mg). Concentrations of glucose ranged from 0.1 to 0.3 mg/mL, and total glucose increased (P < 0.05) from d 25 (3 mg) to d 140 (63 mg) of gestation. Amniotic fluid volume increased (P < 0.01) between d 30 and 140. Concentrations of estrogens in allantoic fluid, maternal uterine artery, and uterine vein increased (P < 0.01) with advancing pregnancy, and concentrations of progesterone in allantoic fluid (P < 0.07) and plasma (P < 0.05) were affected by day of gestation. Concentrations of glucose were greater (P < 0.05) in uterine artery than uterine vein, but concentrations of electrolytes and osmolarity of plasma were not affected by day of gestation. Increases in weights of fetal organs were proportional to increases in fetal weight during gestation. Results of the present study of conceptus growth and development highlight areas of needed research and provide benchmarks for comparisons when evaluating effects of various treatments, environmental conditions, and epigenetics on successful outcomes of pregnancy in sheep.     

植物活性肽对哺乳仔猪屠宰率和胃肠道发育的影响

试验选用7±2日龄的PIC五元杂交系哺乳仔猪400头,研究21日龄仔猪断奶时植物活性肽对哺乳仔猪屠宰率和胃肠道发育的影响。试验仔猪随机分为4组,每组10个重复。各组日粮分别为在玉米-豆粕型基础日粮的基础上添加2%的鱼粉、2%的血浆蛋白粉、2%的植物活性肽和4%的植物活性肽。研究结果表明:日粮中添加4%的植物活性肽后,屠宰率有增高的趋势但差异不显著(P>0.05);日粮中添加植物活性肽可以显著提高胃、胰脏和小肠的重量并显著增加小肠长度(P<0.05);日粮中添加4%的植物活性肽和2%血浆蛋白粉相比可以显著降低胃内pH值(P<0.05)。     

Production of eosinophil chemoattractant activity by ovine gastrointestinal nematodes

Eosinophilia is a well documented feature of helminth infections but the precise nature of the interaction between parasite and eosinophil remains an enigma. This paper describes experiments demonstrating that ruminant gastrointestinal trichostrongyles produce potent chemoattractant activity for ovine bone marrow-derived eosinophils in vitro. This activity was initially identified as a constituent of whole worm extracts of third and fourth larval (L3, L4), and adult stages of Teladorsagia circumcincta, and adult Haemonchus contortus. Similar activity was detected in excretory/secretory (E/S) material derived from live T. circumcincta L3. Subsequently, by adapting the assay technique to incorporate live worms directly into the system, it was shown that L3 of both T. circumcincta and H. contortus produced eosinophil chemoattractant activity. In contrast, neither whole worm extracts, or E/S preparations from mixed stages of the free-living nematode Caenorhabditis elegans contained eosinophil chemoattractant activity, and there was no evidence of chemoattractant production by live C. elegans. The results described are challenging to the traditional dogma that eosinophils are host-protective effector cells, and raise the intriguing possibility that ovine nematodes actively encourage recruitment of eosinophils. Local eosinophil-mediated mucosal damage, comparable to that seen in the asthmatic lung, may then provide a permissive local microenvironment for the parasite. Moreover, if they prove important for pathogenicity, nematode chemoattractants could offer future potential as novel therapeutic targets.     

Factors affecting the survival and migration of the free-living stages of gastrointestinal nematode parasites of cattle in central queensland

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.     

Effects of supplemental degradable intake protein on utilization of medium- to low-quality forages

Three independent experiments were conducted each using 16 ruminally fistulated beef steers fed bermudagrass (8.2% CP, 71% NDF; Exp. 1), bromegrass (5.9% CP, 65% NDF; Exp. 2), or forage sorghum (4.3% CP, 60% NDF; Exp. 3) hays to evaluate the effects of increasing level of supplemental degradable intake protein (DIP) on forage utilization. In each experiment, steers were blocked by weight and assigned to one of four treatments, and hay was offered to each steer at 130% of average voluntary intake for the preceding 5-d period. Supplemental DIP (sodium caseinate) was placed in the rumen at 0700, immediately before feeding forage. Levels of DIP supplementation were .041, .082, and .124% BW; the control received no supplemental DIP. Following a 10-d adaptation, intake and total fecal output were measured for 7 d. In Exp. 1, neither forage OM intake (FOMI) nor fiber (NDF) digestion were influenced (P > or = .20) by increasing level of DIP supplementation. The DIP supplied by the bermudagrass hay was estimated to be 8.2% of the total digestible OM intake (TDOMI) for control steers. In Exp. 2, increasing level of supplemental DIP did not affect (P > or = .26) FOMI but tended to increase total OM intake linearly (TOMI; P = .10). The tendency for a rise in TOMI coupled with a slight numeric increase in digestion resulted in an increase (linear; P = .06) in TDOMI. In the treatment group in which the maximum TDOMI was observed (supplemental DIP treatment of .082% BW), total DIP intake constituted approximately 9.8% of the TDOMI. In Exp. 3, FOMI, TOMI, organic matter digestion (OMD), and TDOMI were improved (P < .01) by increasing amounts of supplemental DIP. Although there was some evidence of a tendency for a decrease in the magnitude of change in TDOMI in response to increasing DIP supplementation, a clear plateau was not achieved with the levels of supplement provided. When the highest level of supplemental DIP was fed, DIP constituted approximately 12.8% of the TDOMI. In conclusion, significant variation was observed among forage in the amount of DIP needed to maximize intake and digestion when expressed in relationship to the digestible OM.     

日粮ADF水平对肉兔胃肠道发育、免疫及屠宰性能的影响

选用60只体重相近的2月龄新西兰肉兔,随机分为5组,分别饲喂5种酸性洗涤纤维(ADF)水平(13%、16%、19%、22%和25%)的日粮,旨在探讨我国家兔适宜的ADF需要量。结果表明:随日粮ADF水平升高,胃占活重比重先增加后降低(P<0.05),小肠占活重比重各处理间差异不显著(P>0.05),盲肠占活重比重显著增加(P<0.05)。日粮ADF水平对试兔胸腺指数日粮影响显著(P<0.05),对脾脏指数影响不显著(P>0.05)。随日粮ADF水平提高,试兔心脏和肾脏相对重量先上升后下降(P<0.05),肝脏相对重量逐渐下降(P<0.05);试兔全净膛和半净膛屠宰率呈先上升后下降的趋势(P>0.05)。由此认为,2～3月龄肉兔适宜的ADF水平为16%～19%。     

Effect of condensed tannins extracted from four forages on the viability of the larvae of deer lungworms and gastrointestinal nematodes

The inhibitory activity of condensed tannins extracted from four forage legume plants were evaluated by using a larval migration inhibition assay. The first (L1) and third (L3) stages of deer lungworm (Dictyocaulus viviparus), and the third stage (L3) of deer gastrointestinal nematodes were incubated with tannins extracted from Lotus pedunculatus, Lotus corniculatus, sulla (Hedysarum coronarium) and sainfoin (Onobrychus viciifolia). The tannins extracted from all the forages had inhibitory activity as measured by their ability to paralyse the larvae and inhibit them from passing through sieves. At the highest concentration used (1200 microg/ml) the tannins extracted from sainfoin had the highest activity against ensheathed L1 lungworm larvae (58 per cent), followed by L. pedunculatus (45 per cent), sulla (42 per cent) and L. comiculatus (35 per cent) when the larvae were incubated at 37 degrees C. The same trend, but with lower activities, was observed when the larvae were incubated at 22 degrees C. Anthelmintic activity against L3 lungworm larvae was evaluated by measuring the death rate of ensheathed L3 larvae after incubation with condensed tannins for two, 24 and 48 hours at room temperature (22 degrees C). The death rate was significantly higher (P<0.001) after 48 hours incubation than after two hours or 24 hours, and significantly higher (P<0.001) after 24 hours than after two hours incubation. Condensed tannins from sainfoin had the highest inhibitory activity followed by L. pedunculatus, sulla and L. comiculatus. The tannins from sainfoin also had the highest activity against L3 larvae of gastrointestinal nematodes, followed by L. pedunculatus, sulla and L. comiculatus. Exsheathed larvae of gastrointestinal nematodes were significantly more susceptible to the action of the tannins than ensheathed larvae.     

Genotypic diversity,a survival strategy for the apicomplexan parasite Theileria parva

The tick-borne protozoan parasite Theileria parva causes East Coast fever (ECF), a severe lymphoproliferative disease of cattle that is a major constraint to the improvement of livestock in eastern, central and southern Africa. Studies in cattle experimentally infected with T. parva have shown that the protective cytotoxic T lymphocyte (CTL) response is tightly focused, with individual animals recognizing only one or two dominant antigens, the identity of which varies with MHC class I phenotype. It is well known that cross-protection between T. parva stocks is limited, but precise evaluation of genetic diversity in field populations of the parasite has been hampered by a lack of molecular markers spanning the genome. A recently described panel of satellite markers has provided evidence for substantial genotypic diversity and recombination but does not provide cover for large segments of the genome. To address this deficiency, we undertook to identify additional polymorphic markers covering these regions and we report herein 42 newly identified PCR-RFLP markers distributed across the 4 T. parva chromosomes, as well as 19 new satellite markers for chromosomes 1 and 2. This brings the total number of available polymorphic markers to 141 for the 8.5 Mb genome. We have used these markers to characterise existing parasite stabilates and have also shown that passage of the parasite through naïve cattle and ticks can lead to substantial changes of parasite populations in resulting stabilates. These markers have also been used to show that passage of mixed parasites through an immunised calf results in the removal of the immunising genotype from the parasite population produced by ticks fed on this animal.     

山东省媒介蜱类种类鉴定及羊泰勒虫病流行病学调查

为了阐明山东省蜱类种类及羊泰勒虫病流行概况,于2012年3月-2013年11月采用形态学鉴定法鉴定收集的14 878只蜱类标本;采用梨形虫、泰勒科通用引物及种属特异性引物对617份羊血液样品进行PCR检测,并对阳性样品18SrRNA基因进行遗传进化分析;分析不同月份蜱类活动频率及羊泰勒虫感染率。结果显示山东省长角血蜱(Haemaphysalis longicornis)和草原革蜱(Dermacentor nuttalli)所占比例分别为75.3%和24.7%,统计学分析显示长角血蜱显著多于草原革蜱(P0.05),为山东省优势蜱种。PCR检测结果显示山东省羊泰勒虫感染率为24.8%;其中吕氏泰勒虫感染率为12.0%、尤氏泰勒虫感染率为11.8%,混和感染率为5.3%,没有检测到绵阳泰勒虫感染,统计学分析显示吕氏泰勒虫和尤氏泰勒虫在羊群的感染率无统计学差异(P0.05),吕氏泰勒虫与尤氏泰勒虫单虫种感染率显著高于混合感染率(P0.05)。遗传进化分析显示山东省吕氏泰勒虫和尤氏泰勒虫与北京分离株分布于同一分支,而区别于西北地区和南方地区分离株,呈现区域聚集性;不同月份蜱类活动频率与羊泰勒虫感染率呈现季节相关性。上述结果表明山东省优势媒介蜱种为长角血蜱,羊泰勒虫感染虫种为吕氏泰勒虫和尤氏泰勒虫,感染率较高,且与媒介蜱类存在相关性,为山东省羊泰勒虫病防控提供科学实验依据。     

Factors associated with gastrointestinal parasite infection in dogs in Rio de Janeiro, Brazil

Factors associated with parasitism by helminths and protozoans in 500 dogs presented to three veterinary clinics in the municipality of Rio de Janeiro from November 2003 to September 2004 were evaluated. Dogs were submitted to physical examination and owners were interviewed about the animal's management. One fecal sample from each dog was examined by centrifugal flotation and sedimentation methods followed by the safranin–methylene blue staining technique. Positive results for gastrointestinal parasites were detected in 46.4% of the examined samples. Infection with protozoans (29.6%) was more frequent than with helminths (23.2%). Cryptosporidium sp. (26.2%) and Ancylostoma sp. (15.2%) were the most frequent parasites. Logistic regression analysis showed that age (p < 0.001), access to soil (p < 0.001), hygiene of the environment (p = 0.001), illness (p = 0.007), owner's level of education (p < 0.006) and veterinary clinic (p = 0.043) were associated with gastrointestinal parasite infections in dogs. Treatment and control are especially important for puppies. Adult dogs should be submitted to fecal examination before treatment, placing special emphasis on those that present one or more factors associated with infection.