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1.
The efficacy of the morantel sustained release bolus in controlling gastrointestinal and lungworm parasites when used in first-season grazing animals which followed older animals onto spring pasture (deprime system) was assessed in three trials conducted in Normandy, France. In each trial first-season grazing calves were equally allocated onto two separate but equivalent paddocks where they remained throughout the grazing season. A morantel sustained release bolus was administered to one group of animals at turnout, the other group remained as controls. The effect of the treatment on contamination of pasture (herbage larval counts and tracer worm counts), on faecal worm egg and lungworm larval counts, and on weight gain performance of the principal animals was assessed. In all three trials, worm egg output in the bolus-treated animals was substantially lower throughout the season compared with the control animals. Worm burdens of tracer calves grazing pastures of the treated cattle were also reduced compared with tracer calves grazing control pastures. Clinical parasitic gastroenteritis occurred in the control animals but not in the bolus-treated animals in one trial. Overall the bolus-treated animals outperformed the controls by a mean weight gain advantage of 10.5 kg (P less than 0.01).  相似文献   

2.
The efficacy of the first of a new generation of intraruminal devices for cattle, the morantel sustained release trilaminate, was assessed in two field trials. In each trial the animals were divided into a control group and a treated group. The device was administered to each calf before turn out in the spring and the reduction of gastrointestinal parasitism resulted in a substantial reduction in the level of pasture contamination with infective helminth larvae later in the season. Compared with the control calves the treated calves had a 94 per cent reduction of worm burdens acquired over the entire grazing season in the first trial, despite the controls being treated for clinical disease in September. In the second trial four anthelmintic treatments were administered to the control calves during the grazing season, but nevertheless a 64 per cent reduction of worm burdens in the treated group compared to the control group was recorded. The control of parasitic infection by the sustained-release devices resulted in mean weight gain advantages of 28.3 kg and 34.7 kg by the treated animals in the first and second trials respectively.  相似文献   

3.
The field application of an intraruminal bolus designed to release morantel tartrate continuously for a period of about 60 days after oral administration to grazing calves just prior to turnout onto spring pasture has been tested. The study involved five separate field trials with a common trial design conducted in 1978 on farms in Eastern and South Eastern England.The Morantel Sustained Release Bolus (MSRB) treated calves showed statistically significant weight gain advantages over their contemporary controls at the end of the grazing season on all sites. Advantages varied from 13.4 to 36.5 kg. Overall 109 treated calves gained an average of 24.5 kg more than controls. Outbreaks of clinical parasitic gastroenteritis occurred in the latter part of the grazing season on three sites. Altogether, there were twenty eight cases requiring therapeutic treatment in controls but none in the MSRB treated calves.Parasitology data show that the disease prevention and improved performance were due to the MSRB preventing the mid-summer rise in pasture larval contamination, which was evident in all five sites, and thus eliminating the detrimental effect of high parasite challenge in the latter part of the grazing season.  相似文献   

4.
The effectiveness of the morantel sustained release trilaminate (MSRT) in controlling gastrointestinal nematodes through a grazing season was evaluated using 60 yearling beef stocker calves randomly divided into 2 groups of 30 animals each. In April 1985, the calves comprising the treatment group each received an MSRT designed to release morantel tartrate continuously for 90 days while those of the control group remained unmedicated. All animals were weighed and samples of rectal feces were taken at 14-day intervals, beginning on Day 0, until trial termination (Day 168). At trial termination, 10 control and 10 treated calves were necropsied for recovery of gastrointestinal nematodes. Three sets of parasite-na?ve tracer calves were utilized to evaluate the initial, interim and final levels of pasture contamination by nematode larvae. Overall, the use of the MSRT resulted in a 75.5% reduction (P less than 0.001) in output of nematode eggs from the principals, an 81.8% reduction (P less than 0.001) in numbers of gastrointestinal nematodes in principals (at trial termination), and a 96.9% reduction (P less than 0.05) of pasture larval nematode contamination (as indirectly indicated by parasite burdens in tracer calves). The mean weight advantage of treated calves was 16.6 kg per head (P less than 0.001).  相似文献   

5.
A grazing experiment was performed in the Swiss midland region with 22 first-season calves which were grazed together from May to mid July when they were allocated to two equal groups, one receiving a morantel sustained-release trilaminate bolus (Paratect Flex) bolus, Pfizer, Zurich, Switzerland) and the other one remaining as an untreated control. Each group was moved to a clean pasture on 21 July. The larval contamination on the pasture with the control animals reached 4652 third stage larvae (L3) per kilogram of dry matter (L3 kg-1 DM) after 10 weeks. Parasitic gastroenteritis was observed in two calves of the control group in August, and mean serum pepsinogen levels exceeded 4000 mU tyrosine in this group in September. Eggs from Ostertagia sp. and Cooperia sp. that were excreted by the animals at the beginning of July and the end of August showed similar hatching rates of 94% and 99%, respectively. In the calves of the bolus group the egg output was reduced by 95% within 14 days of administration of the bolus. Larval contamination on the pasture of the bolus group was zero until the beginning of September when a slight increase occurred, reaching 793 L3 kg-1 DM in October. At the end of the trial the bolus-treated calves had a mean weight gain advantage of 18 kg (P < 0.05) compared with the controls. The results confirm that a second generation of larvae developed on pasture in August and September and caused parasitic gastroenteritis in first-year grazing calves in late summer. The relevance of the results for the prophylaxis of parasitic gastroenteritis in calves in mixed grazing systems with calves and older cattle is discussed.  相似文献   

6.
Three trials were conducted in southern England involving 120 autumn-born calves to evaluate the ability of an oxfendazole pulse-release intraruminal device (OPRB) to control parasitic gastroenteritis (PGE). Matched groups were set-stocked on adjacent paddocks. One group received an OPRB at turn-out; one was treated with an alternative chemoprophylactic programme; while the third acted as an untreated control. In each trial clinical PGE occurred in the latter group but not in OPRB or alternative strategy groups. The OPRB, the morantel sustained release bolus (MSRB) and fenbendazole administered at 3 and 6 weeks after turn-out gave similar weight-gain benefits when compared with untreated controls (P less than 0.01), but the growth rate of animals given regular levamisole treatments from July to housing was significantly poorer than the matching OPRB group (P less than 0.05) although better than controls. Faecal egg-output of OPRB calves was reduced by 97.0-99.9% compared with 95.5 and 58.9% for MSRB and fenbendazole treatments. Consequently, the late summer/autumn peaks in pasture larval counts were considerably reduced in all treatment groups other than the late-season levamisole strategy which reduced overall egg-output by only 37.6%. Serum pepsinogen and gastrin values confirmed a greater degree of abomasal disturbance in calves grazing on the more highly contaminated pastures. Incidental lungworm infections became clinically apparent in the control groups of two trials but not in any OPRB or alternative treatment group.  相似文献   

7.
The efficacy of the oxfendazole pulse release bolus system for the control of parasitic gastroenteritis and parasitic bronchitis in first-season grazing calves was evaluated in Belgium. Twenty-two calves were allocated to two groups. The calves in one group received a bolus at the time of turn out, while the other group remained untreated. The efficacy of the bolus was assessed by comparison of faecal worm egg counts, plasma pepsinogen concentrations, the antibody response to Ostertagia, Cooperia and Dictyocaulus species total plasma protein and albumin concentrations, and weight gains throughout the grazing season and the housing period. The oxfendazole pulse release bolus provided good control of parasitic gastroenteritis dominated by ostertagia. The effects of parasitic gastritis were greatly reduced as shown by the significantly lower values of serum pepsinogen and ostertagia antibody titres. The use of the bolus further reduced the adverse effects of parasitism as indicated by better liveweight gains and normal total plasma protein and albumin concentrations whereas in the untreated control group hypoproteinaemia and hypoalbuminaemia were observed. Most animals exhibited clinical signs of parasitic bronchitis at the end of the grazing season, and the bolus may not adequately control parasitic bronchitis in all cases at all times.  相似文献   

8.
The efficacy of using a bolus containing morantel in a sustained-release preparation for controlling naturally acquired gastrointestinal parasitic infections in weaned calves and yearling cattle was investigated during the 1982 grazing season at selected sites in the United States and Canada. According to a common trial design under various climatic and management conditions, 10 field trials were conducted with the bolus. At the time of spring turnout, a bolus was administered to each calf or yearling in the treated group. Then, treated and control cattle grazed separate but equal areas of divided pasture(s). The epidemiologic pattern of parasitic gastroenteritis in control animals and the effect of treatment on this pattern was determined in each trial. Safety and practicality of use of the bolus also were established. When compared with untreated cattle (control), those given the bolus deposited significantly (P less than 0.05) fewer worm eggs (89% reduction) during the first 90 days of the grazing season, as well as significantly fewer (P less than 0.05) worm eggs (84% reduction) during the entire grazing season. Consequently, during the second half of the grazing season, larval populations on treated pastures remained significantly (P less than 0.05) lower (66% reduction), compared with numbers of larvae found on control pastures. For pastures grazed by treated and control cattle at trial initiation, mean worm counts recovered from tracer calves were equal, indicating comparable pasture contamination at the beginning of the grazing season.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
Prophylactic (summer) and/or therapeutic (autumn) administrations of an intra-ruminal sustained-release bolus (MSRB) containing morantel tartrate were compared for the control of gastro-intestinal nematodes in grazing dairy calves over an 8-month period (December to August). The MSRB was designed to release morantel tartrate at 150 mg/day for 90 days.

Treated and untreated groups of calves grazed separate replicated pastures. Both groups of calves receiving the MSRB at the beginning of summer showed a significant mean liveweight advantage (17.7 kg and 20.7 kg for the summer and summer/autumn treated groups, respectively) at the end of the trial period, when compared with untreated calves. The liveweight advantage of calves receiving the MSRB in autumn only (6.5 kg) was not significantly different from that of the controls.

Both the summer and autumn administrations of the MSRB prevented the accumulation of Pre-Type II burdens of Ostertagia spp.

Retention rates of the MSRB were high and chemical analysis of faecal samples indicated a fairly constant release of the anthelmintic over the predicted 90-day period.

The results indicate that the MSRB is potentially useful for the control of gastro-intestinal nematodes, and particularly for the production of ’safe’ pasture. The MSRB could provide an effective alternative to integrated control based primarily on grazing management.  相似文献   

10.
The morantel sustained release bolus was administered at turnout to first-season grazing calves in order to assess its efficacy in the seasonal control of infection by nematode parasites in Ireland. The pastures grazed by control calves showed a marked increase in gastrointestinal trichostrongylid infective larvae by September, while numbers of infective larvae on pasture grazed by bolus-treated calves remained at a low level throughout the grazing season. In consequence, the controls showed significantly higher worm egg counts in late season and significantly higher worm burdens (mainly Ostertagia spp) at necropsy carried out in November on representative number of principal animals selected from each group. These reduced worm burdens were attributed to the suppression of egg output during the early part of the season as a result of treatment with the morantel sustained release bolus at turnout in the spring. Pasture contamination with Dictyocaulus viviparus larvae was present on all treatment pastures. The bolus-treated calves however were subjected to an increase in D. viviparus infection which occurred on their pasture in late season after the active life of the bolus had expired. It was concluded that bolus treatment delayed (rather than prevented) the buildup of D. viviparus infection on the pasture by 60-90 days.  相似文献   

11.
The direct and indirect anthelmintic efficacies of the morantel sustained-release bolus given to calves were assessed in a 154-day controlled field trial. A permanent calf pasture (divided into 2 lots) and naturally parasitized calves were used. The medicated calves were given the bolus at the time they were placed on the pastures. Control calves did not receive anthelmintic therapy. The effectiveness of the bolus to control parasitic gastroenteritis was determined by monitoring various parasitologic determinants. The treated calves had significantly (P less than 0.01) reduced numbers of fecal nematode eggs for every posttreatment sampling period when compared with the control calves. Tracer calves, used periodically during the study to indicate pasture larval infectivities, had equivalent worm burdens at the beginning of the trial (treated vs control pasture). Tracer calves, added later in the study to the lot with treated calves, harbored 83% to 94% fewer nematodes than did their counterparts in the lot with the controls. Plasma pepsinogen concentrations, reflective of abomasal worm burden size and/or activity, were significantly higher (P less than 0.01) in the control than in the treated calves from day 54 until trial termination. At trial termination, the treated calves weighed an average of 27.8 kg more and harbored 80.9% fewer nematodes than the control calves. The morantel sustained-release bolus is an anthelmintic delivery device that has therapeutic and prophylactic antinematode activities. To achieve its optimum performance, the bolus must be used so that the epizootiologic patterns of the predominate parasitic nematodes are effectively disrupted. Generally, internal nematode parasitisms in the calf flourish during the animal's first springtime grazing period.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

12.
Friesian steers were exposed to natural trichostrongyle infection and left untreated (controls) or treated with either a morantel sustained release bolus or fenbendazole at two week intervals (clean) in each of two consecutive grazing seasons. In the second grazing season the mean liveweight gains of the clean, morantel treated and control groups of cattle over 152 days were 105, 131 and 109 kg respectively (morantel treated greater than clean, control P less than 0.02). The cattle were slaughtered following an indoor fattening period. The dressed carcase weight, killing out percentage and related carcase measurements were superior in the treated groups. Eighty per cent of the clean and morantel treated cattle graded satisfactorily and qualified for subsidy payment whereas less than 30 per cent of the control cattle were successful. Rib joint analyses showed significantly lower total weight, eye muscle weight and area together with a higher bone content in control cattle.  相似文献   

13.
In an experiment carried out in 1981 and 1982, the effect of the use of a morantel sustained release bolus (Paratect bolus) on the weight gain and a number of parasitological parameters of cattle was studied. In the first year 42 calves were divided into 3 equal groups, one group was kept outside and treated with a bolus (B), the second group was kept outside and was not treated (C), while the third group remained indoors (I). Groups B and C were grazed separately on contaminated pasture. During the first months Group B had a negligible egg output. The egg output in the controls was much higher and in mid-August they had to be treated for parasitic gastroenteritis. At the end of the grazing season the advantage in weight gain of Group B was 20 kg compared with the controls. During the housing period the growth in the 3 groups was not significantly different. At the start of the second grazing season half the animals of Groups B, C and I received a bolus (Groups BB, CB and IB). The other half remained untreated (BC, CC and IC). The animals treated with a bolus in 1982 gained significantly more weight (64 g/day) than untreated animals. Heifers turned out for the first time (IB and IC) showed much less weight gain than heifers in their second grazing season. The heifers which had previously grazed in 1981 had a very low egg output compared with Groups IB and IC, although the level of egg output of the latter was also not very high (max, almost 40 (eggs per gram (EPG)). In faecal cultures of heifers of Group BC, CB and CC, no Cooperia oncophora-larvae were seen from May onwards, indicating a strong immunity against this species. In Group BB very low numbers of C. oncophora-larvae were observed. In Groups IB and IC, C. oncophora was present during the whole season. At the end of the first season the level of herbage infestation on the control pastures was much higher. In 1982 only slight differences in level of infestation between the pastures were observed. At the start of the season in 1982 serum pepsinogen levels were much higher in the groups which grazed in 1981, compared with the indoor-fed groups. Groups BC and CC had significantly higher levels than Groups BB and CB and all 4 groups always had higher levels than Groups IB and IC.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   

14.
The pharmacokinetics and gastrointestinal distribution of morantel tartrate release from a sustained release trilaminate bolus in cattle were investigated over a 98-day period post-treatment. Six Holstein calves (125-150 kg) had permanent indwelling fistulae surgically inserted into the rumen, abomasum and terminal ileum. Samples of jugular blood, feces and ruminal, abomasal and ileal fluids were taken on days -3, 1, 4, 7, 10, 14 and weekly up to 98 days post-bolus administration. Morantel tartrate concentrations were measured by HPLC after extraction and clean-up. Morantel was not detected in plasma at any time after bolus administration. High concentrations of morantel tartrate were found in ruminal, abomasal and ileal fluids and feces over 98 days post-treatment. The morantel peak concentration (Cmax) was achieved at Day 1 post-administration in each of these compartments. The steady-state morantel concentration (Css) was achieved at approximately 10 days post-treatment and maintained for 91-98 days post-treatment in these gastrointestinal compartments. The morantel Cmax, Css, area under the zero (AUC) and first moment (AUMC) of the concentration-time curve were significantly higher (P less than 0.01) in feces than in other compartments. The in vivo drug release profile of this device has been determined. Steady-state concentrations for from 91 to 98 days have been confirmed.  相似文献   

15.
An experiment was conducted in calves to investigate the efficacy of a morantel sustained release trilaminate bolus (MSRT) to control gastrointestinal parasitism and to assess the development of immunity during the use of MSRT. Two groups (M and U) of four calves each were infected three times a week with a mixed Ostertagia ostertagi and Cooperia oncophora infection for 12 weeks. Calves of Group M received an MSRT at the start of the experiment. Twenty weeks after the start of the experiment, all animals, including a previously uninfected control group (C), received a challenge with 100,000 Ostertagia and 100,000 Cooperia. After a further 4 weeks all calves were necropsied for worm counts. During the trial calves were weighed and faecal egg counts, larval differentiation and pepsinogen concentrations were determined. The results demonstrated the high level of efficacy of the MSRT in reducing the faecal egg output and preventing parasitic gastroenteritis under conditions of a continuous high rate of infection. Efficacy of treatment was higher for Cooperia than for Ostertagia. Post-mortem worm counts suggested a partially impaired immunity build-up in Group M, at least for Cooperia.  相似文献   

16.
The efficacy of the Paratect Flex-Bolus for the control of parasitic gastroenteritis in calves was evaluated in a field experiment in the Swiss midland region. The bolus was administered to 9 first year grazing calves at 4 to 5 months of age before turnout on June 26 while 9 calves remained as untreated controls. Both groups were rotated between 8 paddocks that had been pregrazed by older cattle in spring. For a period of 12 weeks the faecal egg output of the treated calves was reduced significantly (p < 0.05) compared to the controls, whereas no significant differences were observed in the mean serum pepsinogen values of both groups. At the end of the experiment (November 14) the bolus-treated calves showed a 4 kg weight gain advantage over the controls which was not significant. The mild infection levels in both groups were probably due to the low pasture contamination with infective larvae throughout the season which most likely resulted from the late turnout of the calves. An outbreak of dictyocaulosis was observed in both groups in October and confirmed that the Paratect Flex-Bolus provides insufficient protection against this infection.  相似文献   

17.
Infective 3rd-stage larvae of Ostertagia and Cooperia, obtained from the feces of nonmedicated and morantel sustained-release bolus (MSRB)-treated calves, were orally administered to 2 groups of parasite-free calves. After a 42-day maturation period, a therapeutic dose of morantel tartrate was administered to half of the calves from each group. All calves were necropsied 7 days after treatment. After comparing the nematode counts for the nonmedicated and morantel-treated calves of each group, morantel tartrate was demonstrated to be equally effective against the nonmedicated-derived and MSRB-derived nematode populations. The sensitivity of Ostertagia spp and Cooperia spp to morantel tartrate, therefore, was not diminished after use of the MSRB for a single grazing season.  相似文献   

18.
Summary

The efficacy of the morantel sustained‐release bolus (MSRB) in controlling gastrointestinal parasites in first‐season grazing calves was evaluated on a dairy cattle farm in Belgium. The calves grazed a pasture which had been used by bolus‐treated animals in the three previous years. The effect of bolus administration was determined with respect to live weight gain, faecal egg shedding, herbage larval counts, serum pepsinogen levels and ELISA antibody titres.

In spite of an incomplete reduction of faecal egg shedding during the first months of the grazing season, bolus administration resulted in the prevention of parasitic gastro‐enteritis in the calves. A weight gain advantage of 35,2 kg of the bolus‐treated animals over the controls was noted already at two months after turnout. This weight gain advantage was maintained until housing.

The usefulness of serum pepsinogen values and ELISA antibody titres as parameters in prevention experiments is stressed. Both serological parameters gave more information concerning infection level than did the faecal egg output and the herbage larval counts.  相似文献   

19.
Two experiments were done to evaluate the effectiveness of a slow-release, morantel tartrate, anthelmintic bolus for controlling parasitic gastroenteritis in replacement dairy heifers. In experiment 1, good control of nematode contamination of pasture was indicated by lower worm burdens in tracer calves that grazed with 15 heifers treated orally with a single bolus and by significantly decreased numbers of nematode eggs in the feces of the 15 treated heifers, as compared with numbers of eggs in the feces of 15 nontreated control calves. Significant differences in weight gain were not seen between treated and nontreated heifers, probably due to low amounts of larval exposure, the small number of heifers evaluated, and parasitic resistance in the heifers, which may have developed as a result of prestudy exposure to contaminated pasture. In experiment 2, done 1 year after the 1st experiment, using the same pastures that were used in experiment 1, young heifers were used. Many of the heifers were parasite naive at the beginning of the experiment (ie, nematode eggs were not found before the experiment). Treatment with the bolus was effective in controlling parasitic gastroenteritis in the heifers and in controlling nematode contamination of pasture. Compared with nontreated heifers, treated heifers had significantly higher cumulative weight gains, a significant decrease in plasma pepsinogen concentrations, and a significant decrease in worm egg excretion. The number of worms acquired by tracer calves that were grazed with treated heifers was significantly less than for tracer calves that were grazed with nontreated heifers.  相似文献   

20.
The progress of two groups of 10 calves, which had previously been exposed to trichostrongyle infections by grazing infected pastures, was monitored from housing in October to slaughter the following April. Each of the animals of one group had received a morantel sustained release bolus, the other control group remained untreated. The high faecal egg counts and serum pepsinogen concentrations, together with the clinical signs of ostertagiosis observed in the controls in October, persisted during the first month of housing but improved thereafter. From late November onwards, no difference in feed intake and digestive efficiency was observed between the groups. The control calves exhibited a significantly greater feed conversion efficiency over the period February-April, (7.5 vs. 12.3 kg feed kg-1 liveweight gain, P less than 0.001). This reduced the liveweight advantage of the MSRB group over the controls at housing to 25 kg.  相似文献   

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