Parasitic Gastroenteritis In Lambs Research Articles

Effect of biological control through the daily application of spores of Duddingtonia flagrans in lambs kept under an evasive grazing system in the Netherlands

In 2004, an experiment was carried out to evaluate the effect of biological control through feeding spores of Duddingtonia flagrans on parasitic gastroenteritis in lambs, kept under an evasive grazing system. In total 66 lambs were used. Forty naturally infected 3-month old ram lambs were weaned in mid June, and divided into four groups of 10 lambs. On 21 June, G1–G4 were moved to four separate virtually clean plots, they were moved after 4 and 8 weeks to similar plots, and housed after 12 weeks to be necropsied 16 days later. The other 26 lambs had been raised helminth-free, and were used as pairs of tracer lambs. All but one of these pairs, were grazed during the last 2 weeks on each plot. The remaining pair (TA) was grazed during the last 2 weeks on pasture (30 August to 13 September) on the plot that had been grazed by G3 between 19 July and 16 August, to study inhibited development in Haemonchus contortus. All lambs were fed 200 g of concentrates daily throughout the whole period, and those of G1 and G2 were also fed 500,000 spores of D. flagrans/kg bodyweight daily. The faecal cultures demonstrated a high reduction in yield as a result of fungal application. However, no differences between groups were seen in weight gain, faecal egg counts, pasture larval counts, worm counts and tracer worm counts. H. contortus was the dominant species, and it is obvious that the moves at 4-week intervals prevented the development of severe haemonchosis. This is in particular demonstrated by the much higher worm counts in the two TA tracer lambs grazed. Nevertheless, increases to high faecal egg counts 3 weeks after the first and second moves, indicated acquisition of infection before these moves and at least subclinical haemonchosis. This was supported with the worm counts of lambs and tracer lambs. A higher proportion of inhibited early L4 than in other tracers and than in the permanent lambs were found in the pair of TA tracer lambs. This indicates that moves to new pastures in late summer and autumn delays the onset of inhibition.

A model for predicting parasitic gastroenteritis in lambs subject to mixed nematode infections

A model previously developed for the prediction of parasitic gastroenteritis in lambs arising from infection by the nematode parasite Ostertagia circumcincta has been adapted to consider mixed infection and retested. The importance of the lambs as a contributing source to the summer wave of infective larvae is highlighted as are certain apparent deficiencies in the use of grass sampling techniques as a means of assessing pasture larval contamination.

Gastro-intestinal nematode infection in lambs — A model based on climatic indices for forecasting peak pasture larval contamination

The parasiteOstertagia circumcincta is the primary cause of parasitic gastro-enteritis in lambs during their first season at grass. The life-cycle of this nematode parasite involves the development and survival of the free-living stages on pasture. Accordingly the pasture is the site of deposition, development and transmission of infection and meteorological factors affecting the pasture will affect the parasites. In this paper two empirical models for forecasting the timing of the “summer wave” of infective larvae on pasture are presented. These models are similar in form to that described by Starr and Thomas (1980) but involve different approaches to assessing the temperature and moisture components of the daily index value. Further, using the prediction model described by Paton, Thomas and Waller (1984) as an investigative tool, certain tentative suggestions are made as to a general fundamental weakness of empirical index methods.

Comparing control strategies for parasitic gastro-enteritis in lambs grazed on previously contaminated pasture: A network modelling approach

In practice, protection against ovine ostertagiasis in sheep-management systems is generally achieved by anthelmintic treatment and pasture switching. This paper uses a network model to describe the dynamics of the life-cycle of the parasite when ewes and lambs commence spring grazing on pasture which is contaminated. The model enables the efficacy of several recognised control strategies, involving various frequencies of drug application, to be assessed in regulating the adult worm burden of the lamb. The results indicate that dosing ewes at lambing does not provide adequate control. If lambs only are dosed 6 times between May and September significant control is achieved. Combining ewe and lamb treatments only marginally enhances the level of control obtained by the treatment of lambs alone. However, the most effective method of control was to dose lambs 3 times in May–June and on moving lambs to clean pasture at weaning.

A prediction model for parasitic gastro-enteritis in lambs

Paton G., Thomas R. J. and Waller P. J. 1984. A prediction model for parasitic gastroenteritis in lambs. International Journal for Parasitology 14: 439–445. The parasite Ostertagia circumcincta is a major cause of parasitic gastro-enteritis in lambs in temperate countries. A prediction model is described, based on a mathematical representation of the external and internal stages of the life-cycle. The model is used to predict the numbers of infective larvae on a permanent experimental paddock grazed by ewes and lambs in 1973 and 1974. The “moisture status” of the surface layer of the pasture was found to be of fundamental importance for the successful prediction of the development and survival of the pre-infective larval stages. For the years studied the contribution to the summer wave of infection by lamb derived larvae was particularly significant.

Parasitic gastro-enteritis in lambs — A model for estimating the timing of the larval emergence peak

The life history of the nematode parasites of domestic ruminants usually involves the development and survival of free-living stages on pasture. The pasture is, therefore, the site of deposition, development and transmission of nematode infection and meteorological factors affecting the pasture will affect the parasites. Recently Thomas and Starr (1978) discussed an empirical technique for forecasting the timing of the summer wave of gastro-intestinal parasitism in North-East England in the lamb crop using meteorological data and in particular estimates of the duration of “surface wetness”. This paper presents an attempt to model “surface wetness” and the temperature limitation to nematode development.

Forecasting the incidence of parasitic gastroenteritis in lambs in England and Wales.

An empirical method for forecasting the incidence of parasitic gastroenteritis in sheep in England and Wales is described. The level of disease in lambs in late summer depends on the date soil moisture returns to field capacity (the autumn return date) in the previous year together with rainfall from May to July in the current year. The importance of a late autumn return date and winter weather in relation to disease in stock at other times of the year is also discussed.

The Epidemiology and Control of some Nematode Infections in Grazing Animals

This chapter discusses the epidemiology and control of some nematode infections in grazing animals. The epidemiological effects of differences in the reaction of different hosts to a common parasite are given. The connection between arrested development and the increase in worm egg output seen in many host–nematode systems at or following parturition, and which has come to be called the postparturient, periparturient, or lactation rise, is largely incidental. The chapter discusses the parasitic gastro-enteritis in sheep. The central issue appeared to be whether disease-producing infections were built up by exponential population growth through several generations. As the grazing season progresses, the relative numbers of worms of different species present in lambs change. The worm eggs passed by ewes in the course of the postparturient rise were the source of nearly all the worms that were the cause of disease in their lambs. Strategies for the control of parasitic gastro-enteritis in lambs are presented. Cattle exposed to regular infection gradually acquire a resistance to the establishment of Ostertagia ostertagi (O.ostertagi). The chapter discusses the methods for controling the parasitic gastro-enteritis in cattle and the parasitic bronchitis in cattle and the methods for controling it.

Field trials in sheep with the anthelmintic morantel tartrate. II. Prophylaxis of parasitic gastro-enteritis in lambs

Field trials in sheep with the anthelmintic morantel tartrate. II. Prophylaxis of parasitic gastro-enteritis in lambs

A contribution to the epidemiology of parasitic gastro-enteritis in lambs.

A contribution to the epidemiology of parasitic gastro-enteritis in lambs.