Parasitic Gastroenteritis In Calves Research Articles

Evaluation of doramectin in a programme for season-long control of parasitic gastroenteritis in calves

Doramectin was used in a strategic programme for the prevention of parasitic gastroenteritis in first season grazing calves. Three groups of nine calves were used: group 1 was left untreated, group 2 was treated with doramectin at 0.2 mg/kg at turnout and again eight weeks later, and group 3 was treated with 0.2 mg/kg ivermectin at three, eight and 13 weeks after turnout. Both treatment programmes prevented the gastroenteritis which occurred in the controls. The growth rates of the treated calves were superior, and their faecal egg output, and serum pepsinogen and gastrin concentrations were all substantially lower than those of the control calves. The numbers of Ostertagia species larvae on the pastures grazed by the treated calves were also lower than on the pastures grazed by the control calves.

Control of gastrointestinal nematodes in first-season grazing calves by two strategic treatments with doramectin

Twenty first-season Holstein crossbred calves were used in a study conducted to investigate the efficacy of two strategic treatments with doramectin (s.c. 200 μg kg −1 bodyweight). They were allocated in two equal groups: Group D was treated with doramectin at turn-out and 8 weeks later and Group C served as control group. Tracers were used at turn-out, in August and before housing. At monthly intervals all principal animals were weighed, and their faeces were sampled for faecal egg counts and cultured for larval identification. Serum samples were collected for determination of pepsinogen. Animals were slaughtered for worm counts 3 weeks after housing. Clinical signs of parasitic gastroenteritis (PGE) in Group C necessitated a salvage treatment with pyrantel citrate. No signs of PGE were seen in Group D. The faecal egg output remained very low (less than 50 eggs g −1) in Group D, whereas in Group C a mean geometric maximum of 352 eggs g −1 was observed. Pepsinogen levels were below 2000 mU tyrosine in Group D, compared with maximum levels of 4190 mU tyrosine in Group C. The worm counts of the tracers at housing showed an overall reduction of 94% in the total number of gastrointestinal nematodes present on the D pasture, compared with the C pasture. Worm counts of the principal animals showed an 87.8% reduction in the total worm burden. The present results show clearly that doramectin given at turn-out and at Week 8 controls PGE in calves during the first grazing season.

Epidemiology of trichostrongylidosis in cattle: development of infective larvae in the second part of the grazing period and their contribution to infections in the same year

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 (L 3) per kilogram of dry matter (L 3 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 L 3 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.

Assessment of an oxfendazole pulsed release bolus for control of parasitic gastroenteritis in calves in a rotational grazing system

A group of 71 Friesian bullocks, aged six to nine months, vaccinated against lungworm, were randomly allocated on a liveweight basis to two groups of 40 and 31 animals. At turn-out each calf in the group of 40 calves was dosed orally with a pulsed release bolus designed to deliver five doses of oxfendazole at regular intervals during a period of up to 130 days, the first dose being released about 21 days after administration. The group treated with the bolus grazed 2.4 ha and the control group grazed 3.6 ha of permanent pasture for six weeks before having additional access to similar areas of silage aftermath. The control group was treated 99 days after turn-out and when they were housed with fenbendazole (7.5 mg/kg). Faecal worm egg counts, plasma pepsinogen activities, pasture larval counts and liveweights were recorded fortnightly. Significant reductions in worm egg counts and plasma pepsinogen activities were recorded in the calves dosed with the pulsed release bolus together with significant improvements in the liveweight of younger calves compared with control animals. Pasture larval counts were lower in the fields grazed by animals treated with the bolus.

Nematodirus battus infection in calves.

In studies on the control of parasitic gastroenteritis in calves and sheep, involving an annual rotation of pastures grazed by these host species, it was shown that young cattle could play an important role in the epidemiology of Nematodirus battus, a species usually regarded as a parasite of lambs. Thus, young cattle readily acquired heavy burdens of N battus in spring and the contamination of pastures with eggs from these infections resulted in significant populations of larvae on the herbage, which were infective to both calves and lambs grazed on these pastures in the following year. Although the majority of the N battus eggs hatched in the spring, some hatched in the autumn. The calves developed a strong immunity to N battus during the grazing season as demonstrated by the absence of worms at necropsy in the autumn, despite the presence of infective larvae on the pasture.

Control of parasitic gastroenteritis in calves with the morantel sustained release bolus: effect of prior grazing with adult cattle.

Control of parasitic gastroenteritis in calves with the morantel sustained release bolus: effect of prior grazing with adult cattle.

Early season parasitic gastroenteritis in calves and its prevention with ivermectin.

In a two-year trial involving successive batches of 36 autumn-born steers on two adjacent sites in Hertfordshire, calves treated with ivermectin at three and eight weeks after turn out contaminated pastures much less than untreated control animals. Each year dry summers prevented the larval challenge on the control pastures from building up to high levels until about the time of autumn housing. Atypical outbreaks of parasitic gastroenteritis were recorded in May and June of the second year in both groups of control calves. Clinical and parasitological aspects of these outbreaks are discussed in the context of the epidemiology of the disease. It is concluded that the application of measures to control gastroenteritis can bring benefits in the early part of the grazing season as well as later in the year.

The effects of the use of the morantel sustained release bolus system on calves grazing a highly contaminated pasture in The Netherlands.

The efficacy of the morantel sustained release bolus system for the control of parasitic gastroenteritis in calves was evaluated in the Netherlands. The effect of bolus administration to calves, either on May 1 at the beginning of the summer grazing season or on June 12 after the pasture was mown for silage, was determined in respect of liveweight gain, faecal worm egg output, serum pepsinogen values and worm burdens. In addition, pairs of tracer calves were turned out with each group every four weeks and sacrificed for worm counts in order to monitor pasture larval contamination throughout the grazing period. Compared with nontreated control calves, the worm egg outputs of the bolus-treated calves turned out (Nematodirus helvetianus), while the bolus-treated calves turned out on June 12 had a corresponding reduction of 95 and 100 percent. Over the grazing season the average weight gain of bolus-treated calves turned out on May 1 was 34 kg more than nontreated controls turned out at the same time. Difference in weight gain of the treated and control calves turned out late in the season was 10.5 kg in favour of the treated group. The postmortem worm counts were highest in the control calves turned out early and lowest in the bolus-treated calves turned out late. All tracer calves placed on the paddock grazed by control calves (turned out early) died from parasitic gastroenteritis from July onwards while those from the paddock grazed by the control calves (turned out late) died from parasitic gastroenteritis from September onwards. All the tracer calves placed on the paddocks grazed by bolus-treated calves survived until the intended slaughter date.

Strategic anthelmintic treatment of young cattle during summer in a Mediterranean-type climatic environment

A worm-control program utilising treatment of young grazing cattle with fenbendazole on two occasions during summer was tested in the Mediterranean-type climatic environment of south-west Western Australia. The grazing system aimed to produce steers by introducing three-month-old weaned calves to pasture in mid-winter until they were sold in early summer. Comparisons were made of the numbers of worm eggs passed on to plots by treated and untreated animals during autumn, the performances of treated and untreated cattle and the performances of calves introduced to the plots in mid-winter. The “tracer” calf technique was used to determine the availability of infective larvae on one untreated and one treated plot for each of the two years of the experiment. Treated animals deposited less Ostertagia spp. eggs on to pasture during autumn than did untreated animals in one of the two years. In both years they deposited less eggs of worm species other than Ostertagia spp. Less intestinal worms were acquired by “tracer” calves grazing treatment plots than those grazing no-treatment plots in both years, but there were no differences in the number of abomasal worms acquired. The reduction in availability of infective larvae of intestinal worms was insufficient to prevent the occurrence of parasitic gastroenteritis in calves introduced to the plots in mid-winter. The fenbendazole treatments did not confer any immediate body-weight advantage on treated animals. On both treatment and no-treatment plots, there were few infective larvae available to grazing cattle during early autumn, there was a rapid attainment of peak availability in winter and then a decline to low availability by mid-spring. In one year, infective larvae of intestinal worms (almost exclusively Cooperia spp.) increased in availability again in late spring and early summer. A high proportion of retarded worms was never a feature of the worm counts of “tracer” calves. It was concluded that the treatments may have been more effective had they been given during autumn.

Parasitic gastro-enteritis in calves on the Jos plateau, Nigeria.

An experiment in which groups of calves were repeatedly treated with thiabendazole and compared with similar untreated groups suggested that parasitic gastroenteritis is not a problem in calves kept under traditional management during the wet season on the Jos plateau in northern Nigeria. On the other hand, as the dry season advanced, the effect of earlier treatment during the wet season showed in better weight gains, higher serum albumin concentrations and higher packed cell volumes compared to the controls. The epidemiological significance of this is discussed in relation to the nutritional stresses of the dry season.

Acute parasitic gastro-enteritis in calves in spring.

Acute parasitic gastro-enteritis in calves in spring.

The potential role of pasture management in the control of trichostrongyle worm infection in calves with observations on the diagnostic value of plasma pepsinogen determinations.

Abstract Extract Complete integration of therapeutic treatment with pasture management has been, for many years the preoccupation of veterinary parasitologists seeking the most effective means of controlling trichostrongyle infections in ruminants. The simplicity and effectiveness of this approach has been demonstrated by recent studies in the British Isles. In a series of controlled trials, conducted over several years, Michel (1968 Michel, J. F. 1968. The control of stomach-worm infection in young cattle. J. Br. Grassld Soc., 23: 165–173. [Google Scholar], 1969 Michel, J. F. 1969. Observations on the epidemiology of parasitic gastro-enteritis in calves. J. Helminth., 43: 111–133. [Google Scholar]) has shown that a single change of pasture in summer (to pasture not grazed since winter) accompanied by one effective anthelmintic treatment will adequately control parasitic gastro-enteritis in calves and permit the achievement of linear weight gains.

Experiments on the Control of Parasitic Gastroenteritis in Calves

In three successive years trials were made of measures for the control of parasitic gastro-enteritis in calves, based on the knowledge that the second generation of the worms is the cause of disease and that it becomes available on the herbage in July. A comparison was made between calves which remained on the same pasture throughout the season, calves which were moved in the middle of July to pasture which had not been contaminated since the previous autumn and calves which were given a dose of anthelmintic when moved to such clean pasture. A fourth group consisted of calves which received anthelmintic treatment every week while remaining on infected ground.

Field Observations on the Epidemiology of Parasitic Gastro-enteritis in Calves

A field study of the epidemiology of parasitic gastro-enteritis in calves has shown that both in Northumberland and Durham and in Devonshire, infestations on the pasture fall to a low level by the end of April. If the pasture is contaminated by calves turned out at this time, the infestation on the herbage is unlikely to rise before July. In the south-west, however, contamination before mid-May can result in the appearance of infective larvae on the herbage in the second half of June. Very heavy herbage infestations were frequently seen in the winter. The hazards of turning calves out early in the spring are discussed and some precautionary measures suggested.

Parasitic Gastro-enteritis in Cattle: Factors Influencing the Time of the Increase in the Worm Population of Pastures

In the course of field experiments concerned with the control of parasitic gastroenteritis in calves, observations were made on the rate of development of the free-living stages of Ostertagia ostertagi and Cooperia oncophora in faeces excreted by the calves, on the rate of movement of the infective larvae from the faeces to the herbage, and on the rate of disintegration of the faecal pats, in order to assess the influence of these factors on the time at which a rise in the herbage infestation takes place.

Observations on the epidemiology of parasitic gastro-enteritis in calves.

Over a period of seven years several series of observations were made on infestations of Ostertagia ostertagi and Cooperia oncophora on the herbage of pastures grazed by calves. A regular seasonal pattern was revealed. The concentration of larvae on the herbage falls to a low level in spring. Susceptible calves turned out at this time may begin to contaminate the pasture in mid-May but it is not until July that the infestation on the herbage increases significantly. Generally the increase is to a high level which is maintained with little change until the following spring.Evidence is presented which indicates that contamination of the pasture in the first half of the grazing season is far more effective in the production of an infestation on the herbage than is contamination in the second half of the season.In a discussion of the epidemiology of parasitic gastro-enteritis the formerly accepted view, that clinical helminthiasis results from a continuous build-up of infection in the calves and on the pasture is rejected. It appears that the parasites complete little more than one generation each year.The results of these observations suggest a simple and widely applicable means of controlling parasitic gastro-enteritis in calves.