| efficacy of avermectin b1a for treatment of experimentally induced nematode infections in cattle. | two formulations of avermectin b1a, c-076 and mk-933, were examined for anthelmintic activity in two trials, each using 20 calves with experimentally produced nematode infections. in one trial, c-076 was given orally, and in the other trial, mk-933 was given by injection at dosages of 50, 100, and 200 micrograms/kg of body weight. treated calves were held for 7 to 8 days and then, together with nontreated controls, were euthanatized and were examined for nematodes in their gastrointestinal tract ... | 1980 | 6449894 |
| ivermectin: controlled test of anthelmintic activity in dairy calves with emphasis on dictyocaulus viviparus. | twelve dairy calves, naturally infected with lungworms and gastrointestinal parasites, were selected for a controlled test with single doses of ivermectin, administered subcutaneously, at the dose rate of 200 micrograms/kg. specific interest was on efficacy of ivermectin against lungworms (dictyocaulus viviparus), with ancillary interest directed on abomasal parasites. ivermectin was administered to 6 calves, and the vehicle only, to 6 calves. at necropsy, 7 days after treatment, lungworms were ... | 1981 | 6455949 |
| experimental concurrent infection of cattle with ostertagia ostertagi and salmonella dublin. | six seven-month-old friesian steers were given 8.1 x 10(9) salmonella dublin orally. four had been infected with third stage larvae of ostertagia ostertagi on four occasions over the previous three months. all became pyrexic and excreted s dublin in the faeces for eight to 15 days. intravenous injection of 8.7 x 10(8) s dublin six weeks later produced similarly mild effects in parasitised and control animals alike. two parasitised animals stopped excreting s dublin after three and five weeks res ... | 1984 | 6463384 |
| efficacy of fenbendazole against inhibited larvae of ostertagia ostertagi in yearling cattle. | efficacy of fenbendazole, at doses of 7.5 and 10.0 mg/kg of body weight, against inhibited early 4th-stage larvae of ostertagia ostertagi and other nematodes of the abomasum and intestinal tract, was investigated in naturally infected yearling heifers in late may 1982. in louisiana, this is near the end of the period (march to may) in which maximal numbers of inhibition-prone larvae are acquired. the mean numbers of o ostertagi in 10 untreated control cattle were: adults, 4,880; developing 4th-s ... | 1984 | 6497097 |
| an epidemiological study of trichostrongylidiasis in dairy cattle grazing irrigated pastures. | trichostrongylid burdens in 1 to 2-year-old dairy heifers were estimated after they grazed with a dairy herd for up to 12 months. ostertagia ostertagi, trichostrongylus axei and cooperia oncophora represented 79.5, 12.7 and 7.8% respectively of all trichostrongylids recovered. the largest burden was 97,000 trichostrongyles with less than 20,000 being the typical burden. clinical disease was not observed. the strain of o. ostertagi present was capable of inhibition and was not necessarily control ... | 1984 | 6497788 |
| inhibited development of ostertagia ostertagi in australia related to survival over summer in the host or on pasture. | during autumn and winter, separate pasture plots were seeded with ostertagia ostertagi eggs produced by worms which had persisted in the host over summer as inhibited larvae, or which had developed directly from larvae acquired from pasture in late summer. successive groups of parasite-free calves grazed the plots in spring for 14 days at 4-week intervals and were killed for worm counts 14 days after removal from pasture. the proportion of inhibited early 4th-stage larvae was substantially great ... | 1984 | 6514384 |
| survival of infective larvae of nematode parasites of cattle during drought. | in a study originally designed to determine the seasonal origin of the high levels of availability of nematode larvae to cattle in winter and spring, plots were serially contaminated with eggs of ostertagia ostertagi and cooperia oncophora by naturally-infected calves at monthly intervals from february 1980 to september 1980. the availability of infective larvae was monitored by monthly pasture sampling and larval recovery. because of the intervention of a 15 month drought, recoveries of larvae ... | 1984 | 6538720 |
| negative interactions between ostertagia ostertagi and cooperia oncophora in calves. | the interactions between ostertagia ostertagi and cooperia oncophora were studied in calves by concurrent and sequential infections. a reciprocal negative interaction between the 2 species was found in sequential, but not in concurrent infections. this result was supported by the finding of serological cross-reactions. it is suggested that the negative interaction is immunologically mediated. the depression of weight gain found after infection was similar for o. ostertagi- and c. oncophora-infec ... | 1984 | 6541831 |
| infectivity and pathogenicity of three isolates of ostertagia ostertagi in cattle. | two laboratory-maintained isolates of ostertagia ostertagi and 1 recently isolated from grazing cattle, were compared for their infectivity and pathogenicity in holstein-friesian calves. calves were inoculated with 200 000 and 300 000 infective larvae in 2 experiments. calves in both experiments developed anorexia and diarrhea; generally calves were more severely affected by the larger inoculum. patent infections and clinical signs developed later in the calves inoculated with the field isolate. ... | 1984 | 6542723 |
| low-dosage phenothiazine in the prophylaxis of trichostrongylid infection in calves. | phenothiazine (ptz) given indoors to calves artificially infected with ostertagia ostertagi and cooperia oncophora showed ovicidal activities of 100, 93, 98 and 85% respectively at daily doses of 9, 8, 7 and 6 mg kg-1. in a grazing study, one group of calves was treated with ptz via the drinking water, using a "profel" liquid dispenser. the dispenser was calibrated to add ptz to the water at a daily dose of 7 mg kg-1, but in practice the dose far exceeded this amount. a dose of 7 mg kg-1 day-1 w ... | 1984 | 6543053 |
| efficacy of ivermectin in oral paste formulation against immature gastrointestinal and pulmonary nematodes in cattle. | the anthelmintic efficacy of ivermectin in oral paste formulation was evaluated against the 4th-stage larvae of 8 gastrointestinal nematodes and the common lung-worm in 14 experimentally inoculated calves. two groups consisting of 7 calves each were formed by restricted randomization on body weight. the infective larvae were given orally to the animals on a staggered schedule so that the parasites were in the 4th larval stage when the animals were treated. one group was given vehicle paste, and ... | 1984 | 6547278 |
| ivermectin as an antiparasitic agent in cattle. | in experimental trials on cattle, ivermectin given sc at 200 micrograms/kg had 95% or better efficacy against adult and immature gi and pulmonary nematodes, including inhibited fourth-stage larvae of ostertagia ostertagi. studies of efficacy against ectoparasites revealed nearly 100% efficacy against sucking lice, psoroptic and sarcoptic mange mites and cattle grubs. safety trials revealed no adverse effects with the recommended dosage, including bulls and pregnant cows. a few grub-infested catt ... | 1984 | 6548289 |
| lymphocyte reactivity to ostertagia ostertagi l3 antigen in type i ostertagiasis. | to better understand the immune response of calves infected with ostertagia ostertagi, studies were conducted to examine cell-mediated immune responses to l3 antigen and phytohemagglutinin (pha) by lymphocyte reactivity assay. the l3 antigen was prepared by freeze-thawing and sonication of exsheathed o ostertagi l3. antigen preparations contained 40 to 60 micrograms of protein/ml and no detectable endotoxin. cell-mediated immune responses of peripheral blood lymphocytes were determined in 3 grou ... | 1984 | 6608886 |
| further tests of activity of levamisole on ostertagia ostertagi in dairy calves with notes on overwinter survival of gastrointestinal helminths on pasture. | two controlled tests were conducted in 1981 and 1982 in dairy calves on the university of kentucky research farm to determine activity of the bolus formulation of levamisole given at the dose rate of 8 mg/kg against naturally occurring infections of ostertagia ostertagi. removal efficacies of mature o ostertagi were 98% in the 1981 test (3 treated and 3 nontreated calves) and 94% in the 1982 test (7 treated and 8 nontreated calves). against immature ostertagia spp, removal efficacies were 100% a ... | 1983 | 6625330 |
| comparison of oral and intraruminal administration of oxfendazole against ostertagia ostertagi and cooperia oncophora. | | 1983 | 6649379 |
| persistent anthelmintic effect of ivermectin in cattle. | the persistent anthelmintic effect of ivermectin given subcutaneously at 200 mcg/kg was evaluated against induced infections of haemonchus placei, ostertagia ostertagi, cooperia spp. (c. pectinata and c. punctata), bunostomum phlebotomum and oesophagostomum radiatum in cattle. forty-four friesian bull calves raised under worm-free conditions were restrictively randomized to one untreated control group and 3 ivermectin treated groups of equal size according to mass. animals in the different treat ... | 1983 | 6689429 |
| nematoda: aerobic respiratory pathways of adult parasitic species. | aerobic respiratory pathways have been compared in adult parasitic nematodes, including trichostrongylus colubriformis, nippostrongylus brasiliensis, ostertagia ostertagi, cooperia oncophora, haemonchus contortus, oesophagostomum venulosum, chabertia ovina, dictyocaulus filaria, dictyocaulus viviparus, and ascaridia galli. respiration was measured in both whole worm or tissue homogenates and isolated mitochondrial fractions, and delineated into the mammalian type or alternative respiratory pathw ... | 1984 | 6692887 |
| anthelmintic efficacy, safety, and residue evaluation of levamisole gel formulation in cattle. | anthelmintic efficacy, safety, and residue studies were conducted in beef calves using a levamisole gel formulation. the effectiveness of levamisole gel and tablet formulations was studied in 30 calves with experimental infection of ostertagia ostertagi. removal of 33- to 34-day-old o ostertagi was 99.6% and 97.7%, for the gel and tablet formulation, respectively, when administered orally to supply 8 mg of levamisole hcl equivalent/kg of body weight. a comparative blood concentration study was a ... | 1984 | 6703451 |
| leukokinesis in bovine ostertagiasis: stimulation of leukocyte migration by ostertagia. | a blind-well chemotaxis chamber method was used to indicate migration stimulation of bovine neutrophil and eosinophil polymorphonuclear leukocytes and macrophages as related to ostertagiasis. live exsheathed ostertagia ostertagi 3rd-stage larvae (l3) and soluble l3 antigen (sla), prepared by freeze thawing and sonic disruption of l3, enhanced cellular migration for eosinophils, but not for neutrophils and macrophages. products of lymphocytes cultured with sla for 3 to 6 hours were also examined, ... | 1984 | 6742569 |
| the relevance of in vitro anthelmintic screening tests employing the free-living stages of trichostrongylid nematodes. | the response of the free-living stages of nippostrongylus brasiliensis, nematospiroides dubius, haemonchus contortus, trichostrongylus colubriformis and ostertagia ostertagi to a wide variety of antiparasitic agents in vitro was investigated. all the major broad spectrum veterinary anthelmintics showed good activity against each of these worms with ec50 values varying from about 0.0002 mg/l for certain benzimidazoles and ivermectin to about 6.5 mg/l for febantel. of 22 known narrow spectrum anth ... | 1984 | 6747252 |
| gastrointestinal nematodiasis in dairy cattle. | infection with gastrointestinal nematode parasites appears to be widespread in the cattle population. the pathologically important genera of worms all belong to the family trichostrongylidae. the most pathogenic species is ostertagia ostertagi, which can produce profound changes in abomasal mucosa of affected animals. these nematodes show developmental adaptations, such as seasonally arrested development, that are of prime importance to their survival and persistence on a year to year basis. whe ... | 1982 | 6759538 |
| seasonal changes of gastrointestinal nematode populations in yearling beef cattle in louisiana with emphasis on prevalence of inhibition in ostertagia ostertagi. | | 1983 | 6853015 |
| epidemiological studies on ostertagia ostertagi infections in cattle during their first, second and third summer on pasture. | the number of ostertagia ostertagi in the abomasum of steers, that had been on pasture for one, two or three summers was determined. a total of 44 animals were examined and of these 12 had been out one summer 27 two summers, and five during three summers. during the grazing seasons plasma pepsinogen and serum albumin was determined on all the steers and on 24 heifers during their first summer on pasture. the mean number of parasites in the abomasum after one summer was 128,500 and at the end of ... | 1983 | 6889128 |
| worm burdens in cows. ii. an analysis of the population of nematodes in the abomasa of adult dairy cows. | over a period of one year, from february 1979-february 1980, the abomasa of four dairy cows were examined each week for the presence of parasitic nematodes. based on the identification of adult male worms, ostertagia ostertagi (94%) and trichostrongylus axei (75%) were the most prevalent species, and haemonchus contortus was absent. total worm burdens varied from zero (one cow) to 100,890. the geometric mean total number was 3011. the geometric mean number of arrested larval stages was 685. of t ... | 1982 | 6890273 |
| anthelmintic efficiency of ivermectin against naturally acquired bovine gastrointestinal nematodes. | ivermectin, one of the new avermectin group of anthelmintics, was more than 99 per cent effective in removing all stages of ostertagia ostertagi including inhibited larvae, and adult trichostrongylus axei when administered to cattle orally at 100 microgram/kg body-weight or subcutaneously at 100 and 200 microgram/kg body-weight. high efficacy (> 98.6 per cent) was also obtained against adults and inhibited larvae of cooperia oncophora at 100 microgram/kg orally or 200 microgram/kg by subcutaneou ... | 1980 | 6893775 |
| anthelmintic activities of ivermectin against gastrointestinal nematodes of cattle. | the anthelmintic efficacy of ivermectin, a combined solution of the b1a and b1b fractions of avermectin, was assessed in a controlled trial. twenty-four yearling calves experiencing naturally acquired, clinical gastrointestinal helminthiasis were evenly divided on the basis of weight into two 12-animal groups. the medicated group was given (subcutaneously) ivermectin at the dose rate of 200 microgram/kg of body weight. the control animals were given the vehicle alone, at an equivalent rate. all ... | 1981 | 6895007 |
| anthelmintic efficacy of 22,23-dihydroavermectin b1 against gastrointestinal nematodes in calves. | anthelmintic activities of 22,23-dihydroavermectin b1 (comprised to greater than or equal to 95% 22,23-dihydroavermectin b1a and less than or equal to 5% 22,23-dihydroavermectin b1b) against gastrointestinal nematodes in calves were evaluated in 2 controlled experiments. infective larvae of haemonchus contortus, ostertagia ostertagi, trichostrongylus axei, t colubriformis, cooperia oncophora, and c punctate were given to 11-week-old calves and oesophagostomum radiatum had been given 21 days earl ... | 1981 | 6895285 |
| efficacy of ivermectin against inhibited larvae of ostertagia ostertagi. | the efficacy of ivermectin against inhibited early 4th-stage larvae of ostertagia ostertagi and other nematodes of the abomasum and intestinal tract was determined in naturally infected yearling beef cattle. the time when large numbers of inhibited larvae were acquired was determined by monthly slaughter of monitor cattle, beginning in january. in april, 12 animals were removed from pasture and maintained free of further helminth exposure until slaughter (21 days). at 9 days after the cattle wer ... | 1981 | 6896120 |
| anthelmintic efficacy of ivermectin against immature gastrointestinal pulmonary nematodes of calves. | anthelmintic efficacy of ivermectin (greater than or equal to 80% 22,23-dihydroavermectin b1a and less than or equal to 20% 22,23-dihydroavermectin b1b) was evaluated in a controlled experiment against immature nematodes. twenty calves raised to about 8 weeks of age under nematode-free conditions were allocated into 4 groups. infective larvae of haemonchus contortus, ostertagia ostertagi, trichostrongylus axei, t colubriformis, cooperia oncophora, c punctata, oesophagostomum radiatum, and dictyo ... | 1981 | 6896121 |
| the removal of inhibited early fourth stage ostertagia ostertagi from yearling cattle by mk 933, an ivermectin formulation. | | 1981 | 6946336 |
| reduced activity of levamisole against ostertagia ostertagi in dairy calves. | levamisole bolus formulation was administered in single doses, at rates of 5.8 to 8.1 mg/kg body weight, in 3 controlled tests in male dairy calves (n = 22) in kentucky. removals of natural infections of adult ostertagia ostertagi were 70% and 76% for calves from a hear with a history of regular treatments with levamisole and 85% for calves from a herd receiving levamisole occasionally. activity against other abomasal nematodes and lungworms was also evaluated. | 1981 | 7038437 |
| evaluation of albendazole in cattle naturally infected with nematodes. | albendazole (7.5 mg/kg of body weight) was given to 10 calves naturally infected with gastrointestinal nematodes. ten similar calves served as controls. the compound provided 99% to 100% efficacy in removing haemonchus placei, ostertagia ostertagi, trichostrongylus axei, t colubriformis, nematodirus spathiger, n helvetianus, n filicollis, cooperia oncophora, c punctata, and oesophagostomum radiatum. | 1982 | 7073074 |
| ostertagia ostertagi in calves: a growth nitrogen balance and digestibility study conducted during winter feeding following thiabendazole anthelmintic therapy. | | 1982 | 7085939 |
| ostertagia ostertagi in calves: growth, nitrogen balance and digestibility studies conducted during winter feeding following different fenbendazole therapy programmes. | observations of growth, nitrogen (n) balance and digestibility were made during the first winter housing period upon three groups of calves which had previously been naturally infected with ostertagia ostertagi and which were left either untreated (a) or treated with fenbendazole on three occasions (b) or every two weeks during the entire grazing season (c). the diet given contained sufficient metabolisable energy but only about 60 per cent of the recommended crude protein to sustain a daily gro ... | 1982 | 7089384 |
| ostertagia ostertagi in calves: clinical parasitism and resistance. | | 1982 | 7091854 |
| inhibited development of ostertagia ostertagi in relation to production systems for cattle. | on a coastal farm in new south wales where beef and dairy cattle production was carried on side-by-side, separate pasture plots were contaminated with eggs of ostertagia ostertagi by calves from each production system in autumn, winter or spring. successive groups of parasite-free tracer calves grazed on the plots for 14 days at 4-week intervals and were then killed for worm counts 14 days after removal from pasture. on all plots, the proportion of inhibited early 4th-stage larvae in tracer calv ... | 1982 | 7122124 |
| inhibition of development of ostertagia ostertagi--effect of temperature on the infective larval stage. | populations of ostertagia ostertagi established from fresh larvae and from larvae stored at 4 degrees c for up to 12 weeks contained about 10% inhibited early 4th-stage larvae. this value rose to 21% after 16 weeks, due to an increase in numbers of inhibited larvae while adult numbers remained unchanged. storage at 15 degrees c had no effect. in the case of larvae stored at 4 degrees c for 8 weeks, increasing the larval dose to 90000 had no significant effect on the proportion of the dose which ... | 1982 | 7122125 |
| field study on the epidemiology and pathogenicity of different isolates of bovine ostertagia spp. | the epidemiological features of three different isolates of bovine ostertagia spp under similar initial levels of larval challenge were compared in the field. two of the isolates, consisting mainly of ostertagia ostertagi, and a low proportion of skrjabinagia lyrata conformed in epidemiological behaviour with those investigated by previous workers, though the worm burdens which established did not give rise to the expected clinical signs. the third isolate behaved in a different way, yielding ve ... | 1982 | 7156510 |
| anthelmintic efficacy of febantel against gastrointestinal helminths in calves. | three dosage levels of febantel were tested for anthelmintic activities in calves under field conditions. a total of 20 feeder calves affected with naturally occurring gastrointestinal parasites were used in the controlled test. the calves were allotted to 4 groups of 5 each on the basis of degree of parasitism, body weight, age, and sex. calves in groups ii through iv were treated with febantel paste formulation at dosage levels of 5, 7.5, and 10 mg/kg of body weight; calves in group i were use ... | 1982 | 7165174 |
| oxfendazole: anthelmintic activity in calves artificially infected with six species of nematodes and in calves naturally infested with tapeworms. | in a series of 5 trials, in which 115 artificially infected calves were used, larval anthelmintic tests were done to assess the activity of oxfendazole at 4, 5 mg/kg against all 3 parasitic stages of 6 species of namatodes. an efficacy of over 98% was demonstrated against the 4th stage larvae (l4), 5th and adult stages of haemonchus placei, ostertagia ostertagi, cooperia pectinata, bunostomum phlebotomum and oesophagostomum radiatum and the 3rd larval stage (l3) of h. placei and c. pectinata. ag ... | 1982 | 7175907 |
| [macro-baermann--a method for parasitological examination of herbage samples]. | a baermann technique for extraction of trichostrongylide larvae (l3) from herbage samples is described. the technique is a modification/simplification of a technique previously described by persson (1974). on examination of 150-200 g samples 30-60% of larvae of ostertagia ostertagi and cooperia oncophora were recovered. | 1982 | 7187483 |
| worm burdens of dairy heifers in england and wales. | the size and composition of abomasal worm burdens from 143 casualty and cull dairy heifers were estimated. over 60 per cent had totals of less than 10,000, only four exceeded 100,000 and the overall mean was 16,285. ostertagia ostertagi was almost always present and usually formed the major proportion of the total. trichostrongylus axei was recorded in 83 heifers and was the most common species on 17 occasions. the numbers of arrested early fourth stage worms were highest in winter and declined ... | 1981 | 7197843 |
| persistence on pasture of the infective larvae of nematodes parasitizing maine dairy cattle. | yearling calves infected with ostertagia ostertagi, cooperia oncophora, and nematodirus helvetianus were allowed to graze on a 0.8 ha pasture plot contaminated during june and august 1977. in june 1978, the plot was subdivided into 10 subplots of equal size. grazing in 5 of these plots was allowed, each for 1 month, during june, july, august, september, and october by groups of 2 parasite-free 16-week-old calves. the procedure was repeated in 1979 with the remaining 5 subplots. each group of cal ... | 1980 | 7224300 |
| the repellent effect of gastric contents from uninfected calves for sheathed and exsheathed larvae of ostertagia ostertagi. | | 1981 | 7229812 |
| quantitative modelling and prediction of development times of the free-living stages of ostertagia ostertagi under controlled and field conditions. | the development of the free-living stages of ostertagia ostertagi incubated at constant temperatures from 5 to 27 degrees c and in dung pats in the field was observed. the death rates were adequately described by a single exponential functional and the distribution of times for development by a delayed gamma density function. the times of appearance of selected development stages such as maximum numbers of embryonated eggs and half the maximum number of infective larvae, were highly dependent on ... | 1980 | 7232030 |
| effects on inhibition of development of the transfer of ostertagia ostertagi between geographical regions of australia. | pasture plots in a warm coastal region were separately contaminated in the autumn, winter and spring with eggs of a coastal strain of ostertagia ostertagi derived from dairy calves. at the same times, a parallel set of plots was contaminated by a strain transferred from within a beef cattle management system in a cooler tablelands region. a reciprocal transfer of the coastal strain was also made to the tablelands, where pasture plots were contaminated with eggs of both strains of o. ostertagi in ... | 1981 | 7243348 |
| experimental cross-infections with gastrointestinal nematodes of sheep and cattle. | five parasite-free lambs and five parasite-free calves were infected experimentally with 20,000 third stage gastrointestinal nematode larvae cultured from faeces of sheep from five different farms. in the same way five lambs and five calves were infected with larvae cultured from faeces of calves from five different farms. host specificity of the nematodes was determined using the following parameters: infection rate; number, size, and stage of the worms; their distribution within the gastrointe ... | 1981 | 7245840 |
| further studies on the efficacy of fenbendazole against inhibited larvae of ostertagia ostertagi. | fenbendazole, at low dosage levels, was evaluated for its efficacy against inhibited early fourth stage larvae of ostertagia ostertagi in naturally infected, yearling beef cattle in april. the mean number of inhibited larvae in 10 untreated control cattle was 51,500. at a dosage level of 1 mg per kg (pelleted fenbendazole) per day in feed over five days in 10 cattle, the percentage reduction in comparison to controls was: adults, 85.9 per cent; developing stages, 79.0 per cent; inhibited early f ... | 1981 | 7257120 |
| further observations on the action of fenbendazole against inhibited fourth stage larvae of ostertagia ostertagi. | two further trials are reported on the effect of fenbendazole on inhibited ostertagia ostertagi larvae. in the first trial fenbendazole successfully eliminated inhibited burdens of o ostertagi, while in the second trial the effect was variable. as a result of these trials and previous reports it is concluded that a single oral dose of fenbendazole cannot be relied upon to prevent winter (type 2) ostertagiasis. | 1981 | 7257135 |
| anthelmintic efficacy of albendazole against inhibited larvae of ostertagia ostertagi. | albendazole was evaluated for its efficacy against inhibited early 4th-stage larvae of ostertagia ostertagi for the 3rd consecutive year (april 1979) in naturally infected yearling beef cattle. mean numbers of o ostertagi developmental stages in 10 nontreated controls were: adults, 11,485; developing 4th-stage larvae, 1,370; and early 4th-stage larvae, 51,500. the mean proportion of inhibited early 4th-stage larvae was 76.8%. small numbers of haemonchus sp and trichostrongylus axei were uniforml ... | 1981 | 7258782 |
| the efficacy of fenbendazole at a dosage rate of 5 mg/kg against nematode infestations in cattle. | the anthelmintic efficacy of fenbendazole, dosed to artificially infested cattle at 5 mg/kg live mass was determined against immature and adult haemonchus placei. ostertagia ostertagi, cooperia spp., bunostomum phlebotomum and oesophagostomum radiatum. at this dosage rate, fenbendazole was more than 80% effective in more than 80% of the animals treated against the abovementioned nematodes. the only exception was against the third-stage larvae of b. phlebotomum when it fell to more than 60% effec ... | 1981 | 7265100 |
| inhibition of gastric hydrochloric acid secretions in the rat given ostertagia ostertagi (a gastric parasite of cattle) extract. | the immersion of freshly collected ostertagia ostertagi adults into saline solution (nacl, 0.9%; ph 1.0) resulted in 100% mortality of worms within a 10-minute period. at ph 7.0, mortality was 58% after 270 minutes. at ph 2.2, which approximates the usual abomasal ph, 100% mortality resulted within 60 minutes. in the stomach of rats injected with an extract of o ostertagi (from the abomasum of cattle), there were decreased total secretion of hydrogen ions and volume of secretion (p less than 0.0 ... | 1981 | 7271014 |
| efficacy of levamisole against abomasal nematodes and lungworms in dairy calves: preliminary tests indicating reduced activity for ostertagia ostertagi. | dairy calves (n = 18) were used in controlled tests to evaluate activity of levamisole against abomasal nematodes and lungworms. two formulations of levamisole, injectable (experiment a) and bolus (experiment b), were given in single doses at rates of 6 mg/kg of body weight and 5.4 to 10.2 mg/kg (5.4, 7.6, 8.0, 8.8, or 10.2 mg/kg), respectively. experiment a included 4 treated and 4 nontreated calves and experiment b consisted of 5 treated and 5 nontreated calves. aggregate removals of ostertagi ... | 1981 | 7271028 |
| seasonal occurence of infective nematode larvae on irrigated pasture grazed by cattle in california. | during the period extending from dec 1, 1975, to dec 22, 1976, 3 distinct peaks in the concentration of infective nematode larvae on pasture forage were detected by use of helminth-free tracer calves. two of these peaks, 1 occurring in the spring and 1 in the fall, consisted mainly of ostertagia ostertagi and cooperia sp. it is concluded that these 2 peaks can be anticipated annually and constitute unsafe periods of grazing. the 3rd peak was comprised largely of haemonchus placei and cooperia sp ... | 1981 | 7271041 |
| failure of white-tailed deer (odocoileus virginianus) to serve as experimental hosts for ostertagia ostertagi stiles, 1982. | | 1981 | 7328473 |
| studies on the epidemiology of ostertagia ostertagi in calves. | | 1980 | 7360619 |
| recovery of dead early fourth stage ostertagia ostertagi following benzimidazole administration. | | 1980 | 7361398 |
| ostertagia ostertagi infection and reinfection in cattle of different ages. | twelve cattle, three per group, were each inoculated orally with 100,000 ostertagia ostertagi infective larvae when they were 2 months, 4.5 months, 12 months, and 24 months-old, respectively. signs of clinical parasitism did not develop through 30 days when the infections were terminated with an anthelmintic. the cattle were each reinoculated with 500,000 o ostertagi larvae 6 days later. groups i to iii then developed anorexia and diarrhea after 3 weeks. one calf, inoculated at 2 months of age, ... | 1980 | 7369596 |
| studies on the effect of treatment with anthelmintics on weight gain in calves, naturally infected with gastrointestinal nematodes. | to avoid disease outbreaks caused by gastro-intestinal nematodes different prophylactic measures are recommended. in this connection pasture hygienic achievements and anthelmintics are used. in practice it is often difficult to realize pasture hygienic steps as move the animals to parasite free areas and to avoid that they come back to the infected. in many cases the parasite control is limited to routine deworming. our intention was to study if anthelmintic treatment without other measures had ... | 1980 | 7433013 |
| seasonal availability of nematode larvae on pastures grazed by cattle in new south wales. | trends in the numbers of infective menatode larvae on pasture plots contaminated by cattle at different seasons of the year were defined in 3 different climatic regions. the main nematodes were ostertagia ostertagi, trichostrongylus spp, haemonchus spp and cooperia spp. on the north coast of new south wales with a sub-tropical climate, the numbers of infective larvae of all 4 nematodes rose rapidly to peak levels soon after each seasonal period of contamination began, then fell quickly within a ... | 1980 | 7436894 |
| seasonal changes in the structure of nematode populations of cattle in new south wales in relation to inhibited larval development. | pasture plots in 3 climatic regions were contaminated with worm eggs of ostertagia ostertagi, trichostrongylus axei, haemonchus spp and cooperia spp in the autumn, winter and spring. successive pairs of parasite-free calves were grazed on the plots for 7 to 10 days at 4-week intervals and then killed for worm counts 14 days after their removal from pasture. on the northern tablelands of new south wales, irrespective of the season of pasture contamination, the degree of inhibition of o. ostertagi ... | 1980 | 7436895 |
| survival and development of larvae of the common nematodes of ruminants after long-term cryopreservation and investigation of different routes of infestation. | exsheathed infective larvae (l3) of 16 species of nematodes were tested for infectivity in either sheep or cattle after they had been frozen and stored in 0,09% nacl solution in the gas phase of liquid nitrogen for periods of up to 59 months. a mean of greater than 90% of the l3 of haemonchus contortus, ostertagia circumcincta, trichostrongylus axei, trichostrongylus colubriformis, nematodirus spathiger, oesophagostomum columbianum and chabertia ovina of sheep and haemonchus placei, ostertagia o ... | 1980 | 7465164 |
| efficacy of a spring strategic fenbendazole treatment program to reduce numbers of ostertagia ostertagi inhibited larvae in beef stocker cattle. | efficacy of a spring strategic treatment program with fenbendazole (fbz) to reduce the accumulation of ostertagia ostertagi inhibited early fourth-stage larvae (el4) was investigated in two groups of crossbred beef heifers which were 7-9 months of age and ranged in weight from 155 to 223 kg. the cattle were allocated to groups and treated on 27 april (day 0). group 1 calves served as nontreated controls. group 2 calves were treated with fbz 10% drench suspension at 5 mg kg-1 on day 0 and with 6- ... | 1995 | 7483236 |
| persistent anthelmintic activity of ivermectin against gastrointestinal nematodes of cattle. | two experiments were conducted to determine persistence of ivermectin (ivm) anthelmintic activity. in the first experiment, the injectable (inj) formulation at a dosage of 200 micrograms/kg of body weight and pour-on (po) formulation at a dosage of 500 micrograms/kg were compared in 5 groups of calves (n = 6/group). calves were treated at 14 and 7 days prior to experimentally induced infection. experimental groups were: 1--untreated, infected controls; 2--ivm po, day -14; 3--ivm po, day -7; 4--i ... | 1995 | 7486394 |
| influence of early season moxidectin treatments on acquisition of immunity to ostertagia ostertagi in calves. | | 1995 | 7502955 |
| efficacy of ivermectin pour-on against ostertagia ostertagi infection and residues in the american bison, bison bison. | sixteen american bison, bison bison, were artificially infected with 10(5) infective stage larvae of ostertagia ostertagi on 21 april 1993. at 42 days post-infection eight bison were treated with 0.5% ivermectin pour-on (500 micrograms/kg bodyweight) and eight treated with the carrier only. bison were necropsied 17 and 18 days post-treatment (21 and 22 june 1993, respectively). mean (+/- se) of 5,413 (+/- 1,716) adults and 565 (+/- 305) immature o. ostertagi were recovered at necropsy from bison ... | 1995 | 7563426 |
| anthelmintic profile of the cyclodepsipeptide pf1022a in in vitro and in vivo models. | a novel cyclodepsipeptide of fungal origin, pf1022a, recently was reported to have anthelmintic activity. to supplement published reports and determine potential utility of pf1022a as a ruminant anthelmintic, the compound was examined in in vitro and in vivo models. assays used measured motility of haemonchus contortus (intrinsic drug potency), atp levels (parasite death), and activity against h. contortus, ostertagia ostertagi, and trichostrongylus colubriformis in the jird (spectrum, potency, ... | 1995 | 7592027 |
| an evaluation of abamectin given at turnout and six weeks after turnout for the control of nematode infections in calves. | two groups of 16 set-stocked calves were used to evaluate a new strategy for the prevention of parasitic bronchitis and parasitic gastroenteritis. one group was left untreated while the calves in the other were treated with abamectin at 0.2 mg/kg at turnout and again six weeks later. the treatment prevented the output of nematode eggs and lungworm larvae in faeces for at least 70 days. the number of infective larvae subsequently appearing on the pasture was reduced by 90.2 per cent and the infec ... | 1995 | 7604518 |
| bilateral, perivulval cuticular pores in trichostrongylid nematodes. | a new hypodermal gland was discovered in female nematodes of the family trichostrongylidae. because the new structure appears to be associated with the vulva, it was named the perivulval pore. it is similar, based on light and scanning electron microscopy, to phasmids that are located laterally on the tails of nematodes of the class secernentea. like phasmids, perivulval pores are paired and bilateral, with cuticular ducts to the surface in the areas of the lateral chords. they are located sligh ... | 1995 | 7623208 |
| immunisation of calves with ostertagia ostertagi fourth stage larval antigens failed to protect calves from infection. | excretory-secretory and somatic antigens of ostertagia ostertagi fourth stage larvae, emulsified with complete freund's adjuvant, were intraperitoneally administered to calves on three occasions. two weeks after the last immunisation all calves were infected with a single dose of 130,000 o. ostertagi third stage larvae. all animals were necropsied 25 days after infection. the immunisation procedure resulted in igg1 and igg2 antibodies, however no protective immunity was induced as o. ostertagi w ... | 1995 | 7657462 |
| effect of treatment with an ivermectin sustained-release bolus on productivity of stocker beef calves. | three groups of 30 crossbred beef steers, 8-10 months of age and ranging in weight from 158 to 320 kg, were used to compare effects of treatment with an ivermectin sustained-release bolus or two ivermectin injectable treatments on parasite control and productivity in relation to untreated controls during a 168 day winter-spring grazing period. each group of 30 consisted of five cattle on each of six separate 1.6 ha pastures. treatments on day 0 (12 december) were: group 1: untreated controls; gr ... | 1995 | 7676602 |
| immunoglobulin e and type i hypersensitivity in bovine ostertagiosis. | a series of experiments were performed to determine whether immunoglobulin e (ige) and type i hypersensitivity reactions might be involved in the immune response of cattle to infection with ostertagia ostertagi. the following observations were made. (1) when calves were lightly infected, serum ige levels paralleled worm burdens. however, in heavy infections, both serum and lymph ige levels were inversely related to burdens of o. ostertagi. (2) increases in mediators, especially histamine and leu ... | 1993 | 7683445 |
| interactions between ostertagia ostertagi and cooperia oncophora in calves. | development of immunity to ostertagia ostertagi and cooperia oncophora and interactions between both species in primed calves were investigated after homologous, heterologous and concurrent challenge infections. worm counts, faecal egg output, igg1 and igg2 antibodies and the presence of globule leucocytes were used to evaluate the possible interactions. results show that immunity build-up against o. ostertagi is slow in comparison with c. oncophora. the presence of early fourth-stage larvae and ... | 1995 | 7732636 |
| a comparison of early and mid grazing season suppressive anthelmintic treatments for first year grazing calves and their effects on natural and experimental infection during the second year. | a comparison was made of the efficacy and parasitological sequelae over 2 years, of continuous and intermittent periods of anthelmintic suppression applied both early and in the middle of the first grazing season of calves. five groups of 15 calves grazing separate paddocks within the same field were allotted to one of the following treatment regimes during their first year at grass: group 1, untreated controls; group 2, treated with ivermectin injections at 3, 8 and 13 weeks after turnout; grou ... | 1995 | 7732654 |
| persistent efficacy of moxidectin against dictyocaulus viviparus and ostertagia ostertagi in cattle. | | 1995 | 7771074 |
| parasite control in transhumant situations. | transhumance is defined as 'seasonal moving of livestock to regions of different climate'. it is an integral part of livestock production in many parts of the world and takes several forms including moving of livestock from lowland to mountainous pastures or from dry to humid areas. the impact of transhumance on parasite populations of livestock and on parasite control is described, mainly using examples from europe. the epidemiology of trichostrongylidosis of cattle, mainly caused by ostertagia ... | 1994 | 7846845 |
| ingestion of host immunoglobulin by three non-blood-feeding nematode parasites of ruminants. | host immunoglobulin was detected in homogenates of adult worms or fourth stage larvae of haemonchus contortus, ostertagia ostertagi, o circumcincta and dictyocaulus viviparus, but not in preparasitic third stage larvae of h contortus. all the worms had been washed in detergent before being homogenised to remove any immunoglobulin adhering to the cuticle. this procedure, the concentrations of immunoglobulin detected and observations on sections of the worms stained with fluorescent anti-sheep imm ... | 1994 | 7871262 |
| nematode burdens and productivity of grazing cattle treated with a prototype sustained-release bolus containing ivermectin. | one hundred and twenty four-month-old hereford-friesian cross heifers weighing from 88 to 130 kg were divided into two equal groups. one group acted as a control with each animal receiving one placebo bolus, the other animals received one prototype intraruminal sustained-release bolus designed to deliver approximately 8 mg ivermectin/day for 100 to 120 days. the boluses were administered the day before turnout in mid-may. each group was grazed separately for 167 days on pastures contaminated wit ... | 1994 | 7871690 |
| ostertagia ostertagi: changes in lymphoid populations in the local lymphoid tissues after primary or secondary infection. | the purpose of this study was to begin to define the changes in the local lymphoid tissues that accompany ostertagia ostertagi infection in naive and immunized calves. abomasal lymph nodes were taken from calves beginning as early as 2 days post-infection. phenotypic changes in the resulting lymphocyte populations were assessed by flow cytometry utilizing monoclonal antibodies specific for the cell surface determinates cd2, cd4, and cd8. changes in antigen specificity were determined by limiting ... | 1994 | 7886908 |
| identification and isolation of a 19.7 kda ostertagia ostertagi specific antigen and evaluation of its potential for immunodiagnosis. | ostertagia ostertagi adult worm extracts were analysed by western blotting using sera from calves experimentally infected with o. ostertagi and cooperia oncophora. strong differences in antigen recognition were noticed, even between animals from the same group. two ostertagia specific antigens with apparent molecular mass of 19.7 (ooa19.7) and 20.7 kda (ooa20.7) were identified. one of them (ooa19.7) was purified by three subsequent chromatographic steps, i.e. gelfiltration, ion-exchange and rev ... | 1994 | 7928070 |
| an attempt to implement the nematode-trapping fungus duddingtonia flagrans in biological control of trichostrongyle infections of first year grazing calves. | an attempt was made to control ostertagia ostertagi by feeding the nematode-trapping fungus duddingtonia flagrans (dsm 6703) to grazing calves. one group of calves (group e) was fed the fungal material in the first two months of the grazing season while another group was a non-treated control group (group c). group e showed significantly lower faecal egg count in august and september. on four occasions in july and september, the herbage larval counts were significantly lower on the plot with the ... | 1994 | 7930461 |
| effectiveness of doramectin for treatment of experimentally induced gastrointestinal tract larval nematode infections in calves. | anthelmintic efficacy of doramectin, a macrocyclic lactone of the avermectin family, was evaluated against larval parasitic nematodes in calves. the investigational product was given sc at a dosage of 0.2 mg/kg of body weight to 10 calves infected 6 days previously with third-stage larvae of the genera haemonchus, ostertagia, cooperia, and nematodirus. ten additional calves with identical larval exposure were given saline solution sc also at 6 days after inoculation, and served as the nonmedicat ... | 1994 | 7944021 |
| antigenic analysis of dictyocaulus viviparus by use of test-positive bovine sera. | an antigen extract of dictyocaulus viviparus was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the antigen-recognition patterns of serum antibody from cattle not infected, cattle infected with d viviparus, and cattle with unknown history of d viviparus were analyzed by the use of elisa and western blotting techniques. cross-reactive antibody-recognition patterns were determined by comparing western blots of d viviparus-positive sera with blots of d viviparus-n ... | 1994 | 7998700 |
| treatment of multiple resistant field strain of ostertagia spp. in cashmere and angora goats. | a multiple resistant field strain of gastro-intestinal nematodes was detected in cashmere and angora goats imported from new zealand. different treatments with three types of broad spectrum anthelmintics (albendazole, levamisole/tetramisole and ivermectin) at various dose rates are described. satisfactory effect in angora goats was not achieved until all three anthelmintics were administered simultaneously at twice the normal sheep dose. post mortem worm counts and identification revealed that t ... | 1994 | 8070950 |
| genetic structure of populations of ostertagia ostertagi. | most genetic work to distinguish strains of parasitic helminths focuses on searching for genetic markers to correlate with phenotypes of interest, but in this study genetic diversity among individual ostertagia ostertagi adults is partitioned into components within and between populations. restriction fragment polymorphism data on mitochondrial dna from ten individual worms from each of five different parasite populations are analyzed. three of these populations are characterized by arrested lar ... | 1993 | 8097898 |
| abomasal lymphatic lymphocyte subpopulations in cattle infected with ostertagia ostertagi and cooperia sp. | abomasal lymphatic cannulation was performed on steers naturally or experimentally infected with ostertagia ostertagi and cooperia sp.. abomasal lymphatic lymphocyte subpopulations were evaluated using antibodies specific for bovine mononuclear cell surface antigens, followed by flow cytometric analysis. when compared with the non-infected or experimentally infected steers, naturally infected steers with type 1 or type 2 ostertagiosis had increased percentages of b-lymphocytes. the percentages o ... | 1993 | 8116222 |
| prevention of pathophysiologic and immunomodulatory effects of gastrointestinal nematodiasis in calves by use of strategic anthelmintic treatments. | effects of strategic anthelmintic treatment on pathophysiologic and immunomologic changes induced by infection with ostertagia ostertagi and cooperia oncophora were studied in 2 groups, of 12 calves each: an infected group, inoculated with 200,000 mixed o ostertagi and c oncophora third-stage larvae (l3) on day 1; and an infected-treated group, similarly inoculated, but treated with ivermectin at 9 and 33 days. all calves were also inoculated at 12 weeks with brucella abortus vaccine, at 13 week ... | 1993 | 8116936 |
| partial characterization of proteolytic enzymes in different developmental stages of ostertagia ostertagi. | proteolytic enzymes present in extracts of third (l3) and fourth (l4) stage larvae and adults of the cattle nematode ostertagia ostertagi were defined on the basis of ph optima and proteinase inhibitor sensitivity in spectrophotometric assays using azocasein and elastin-orcein as protein substrates. evidence that different classes of proteinases are expressed in a stage specific manner was provided by the contrasting ph optima and inhibitor sensitivities shown by the enzymes in the different par ... | 1993 | 8132971 |
| efficacy of injectable abamectin against gastrointestinal tract nematodes and lungworms of cattle. | efficacy of abamectin against gastrointestinal tract nematodes and lungworms of cattle was determined in 4 experiments. the first 2 experiments were controlled trials in which efficacy was determined at necropsy in calves with either experimentally induced (n = 14) or naturally acquired (n = 16) infections. half the calves in each experiment were treated with abamectin (200 micrograms/kg of body weight, sc), and half were left untreated as controls. efficacy was > 99% against adult stages of dic ... | 1994 | 8192257 |
| abomasal interstitial fluid-to-blood concentration gradient of pepsinogen in calves with type-1 and type-2 ostertagiosis. | pepsinogen and protein concentrations were determined in blood samples, collected from the left gastroepiploic artery and vein, and in abomasal lymph from 15 steers naturally infected with ostertagia ostertagi and 4 uninfected steers. in steers with type-1 ostertagiosis, the concentration gradient between the mucosal interstitium and the blood alone could account for higher than normal serum pepsinogen concentrations. high interstitial pepsinogen concentrations may have resulted from increased e ... | 1993 | 8214898 |
| characterisation of ostertagia ostertagi antigens by the different bovine immunoglobulin isotypes. | antigenic differences between the developmental stages of ostertagia ostertagi were studied by sds-page and western blotting. gel electrophoresis showed a complex protein pattern different for every stage with the o ostertagi fourth stage larvae (l4) showing an intermediate protein pattern between the third stage larvae (l3) and the adult stage. immunoblotting showed that igg1, igg2 and igm immunoglobulins present in serum from uninfected calves identified several o ostertagi antigens at every s ... | 1993 | 8235088 |
| activity of doramectin against nematode endoparasites of cattle. | a series of 28 controlled anthelmintic studies, involving 634 cattle, was conducted throughout north america and europe to evaluate the efficacy of doramectin against a broad range of gastrointestinal parasitic nematode species and lungworms in naturally and experimentally infected animals. within each study, one or two groups were treated with doramectin at 200 micrograms kg-1 and another group received no drug treatment. worm burdens were estimated by standardised techniques, and efficacy asse ... | 1993 | 8236735 |
| efficacy of doramectin against field nematode infections of cattle in latin america. | two studies were conducted, one in argentina and one in brazil, to evaluate the therapeutic efficacy of doramectin administered subcutaneously at a dose rate of 200 micrograms kg-1 (1 ml per 50 kg) to cattle harboring mixed field infections of gastrointestinal nematodes. in each trial, 20 heifers were randomly allocated to a control or treated group of ten animals each, on the basis of fecal egg counts. animals in the treated and control groups received an injection of doramectin or saline in th ... | 1993 | 8236736 |
| persistent efficacy of doramectin against experimental nematode infections in calves. | three studies were conducted involving cattle exposed to experimental nematode infections. these studies were designed to investigate the prophylactic activity of a single subcutaneous treatment of doramectin at 200 micrograms kg-1 body weight against infections of ostertagia ostertagi, cooperia oncophora and dictyocaulus viviparus. for each study, parasite-naive calves were randomly allocated to either a treated or a matched control group. one group received doramectin and the other received do ... | 1993 | 8236737 |
| doramectin--a potent novel endectocide. | doramectin, 25-cyclohexyl-5-o-demethyl-25-de(l-methylpropyl)avermectin a1a, was selected as the best of a series of novel avermectins prepared by mutational biosynthesis. the primary evaluation of its in vivo antiparasitic activity was carried out using a rat trichostrongylus colubriformis model and a rabbit psoroptes cuniculi model. in each case the new avermectin performed favourably relative to dihydroavermectin b1a (dhavm), the major component of ivermectin. doramectin was extensively evalua ... | 1993 | 8236738 |
| efficacy of doramectin in the prevention of gastrointestinal nematode infections in grazing cattle. | two studies were performed to investigate the efficacy of doramectin in the prevention of infection with ostertagia ostertagi and cooperia oncophora in grazing calves. in each study, 24 parasite-naive calves were randomly allotted to two equal groups and treated with either doramectin at 200 micrograms kg-1 or saline prior to mid-season turnout (day 0) onto contaminated pasture. faecal egg counts were carried out twice weekly from 15 to 64 days after turnout and the cumulative faecal egg count w ... | 1993 | 8236739 |
| comparison of three enzyme immunoassays for diagnosis of dictyocaulus viviparus infection. | three enzyme-linked immunosorbent assays (elisa) that detect antibodies against dictyocaulus viviparus in cattle were compared for sensitivity, specificity and seroconversion after primary infection. these assays were (i) an indirect elisa with crude somatic antigens from adult d. viviparus (ca-elisa), (ii) an indirect elisa with purified antigens (sa-elisa) isolated from somatic antigens of adult d. viviparus and (iii) a competition elisa with antigen purified with anion chromatography in combi ... | 1993 | 8249247 |
| description of ostertagia ostertagi and ostertagia leptospicularis hybrids in experimentally infected sheep. | hybrids of ostertagia ostertagi and ostertagia leptospicularis, derived from experimental infections in sheep, are described. morphometrics of the hybrids were intermediate between those of parental lines for a large range of parameters (distance from apex to cervical papillae and length of esophagus for males and females, length of spicules for males, and length of vestibule, distance from vulva to the end of tail, width of tail at anus). the morphological relationship between hybrids and their ... | 1993 | 8277380 |
| sds-page profiles of somatic proteins from third-stage infective larvae of ostertagia ostertagi and cooperia oncophora. | sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) profiles of somatic proteins from third-stage infective larvae of ostertagia ostertagi and cooperia oncophora were evaluated using laser densitometry. several protein bands were present from both parasite preparations. a few bands from each parasite appeared to be unique. purification of these proteins for use in serologic monitoring of cattle naturally infected with o. ostertagi and c. oncophora should allow circumvention of c ... | 1993 | 8291192 |
| ostertagia, haemonchus, cooperia, and oesophagostomum: construction and characterization of genus-specific dna probes to differentiate important parasites of cattle. | partial genomic dna libraries for four common cattle parasites, ostertagia ostertagi (oo), haemonchus placei (hp), cooperia oncophora (co), and oesophagostomum radiatum (or), were generated and differentially screened with radiolabeled homologous and heterologous genomic dna. clones were identified from each parasite species which did not cross react with dna from the heterologous genera by southern blot or slot-blot analyses. four clones, poo2, php2.1, pco2, and por14 were chosen for further ex ... | 1994 | 8299764 |