Population regulation in trichostrongylids of ruminants

Barger, I.A.

doi:10.1016/0020-7519(87)90129-9

Cited by 29 publications

(15 citation statements)

References 41 publications

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“…41 The possibility that faecal egg counts and adult populations may be independent of larval intake is consistent with the concept of density-dependent population regulation as described by Barger (1986). After dosing 6-month-old lambs weekly for 15 weeks with different numbers of infective Haemonchus contortus larvae, Barger et al (1985) found that worm burdens during the first 6-9 weeks were positively related to the rate of infection.…”

supporting

confidence: 53%

Effect of cattle grazing strategies and pasture species on internal parasites of sheep

Moss

Burton

Scales³

et al. 1998

New Zealand Journal of Agricultural Research

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The results of a three-year study in New Zealand undertaken to compare the effect of alternating sheep and cattle grazing and of different pasture species on internal parasitism in lambs is reported. Despite the commonly held belief that the use of cattle in sheep production systems improves sheep health by reducing nematode burdens, this did not occur. Cattle substantially reduced pasture larval numbers. However, this failed to reduce parasite burdens in lambs as those managed in the absence of cattle apparently developed increased immunity to parasites in response to the greater larval availability. Varying the number of successive grazings by sheep or cattle from 1 to 4 did not change this result. Lamb carcass weights were improved by the presence of cattle, primarily because of improvements in pasture quality. Substituting 30% of the ryegrass area with lucerne or replacing ryegrass with a multi-species mix A 96082 Received 3 December 1996; accepted 24 June 1998 consisting predominantly of bromes, tall fescue, phalaris, timothy, and red and white clover, had no effect on lamb faecal egg counts or worm burdens. Lamb liveweight was not affected by herbage species. Both lucerne and the multi-species mix increased the requirement for conserved feed during winter compared with ryegrass-based systems.

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supporting

confidence: 53%

Effect of cattle grazing strategies and pasture species on internal parasites of sheep

Moss

Burton

Scales³

et al. 1998

New Zealand Journal of Agricultural Research

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“…This is particularly evident for Ostertagia species, important parasites of cattle and sheep (Michel, 1963(Michel, , 1969Callinan & Arundel, 1982;Coop et al, 1985). Such variation between parasitic helminth populations may be due to variations in the rate of worm egg production, a regulatory mechanism considered to be important in the regulation of many gastrointestinal parasite populations (Barger, 1987). In the red grouse-T. tenuis host-parasite system, our findings suggest that density-dependent suppression of egg production is weak or non-existent, at least up to the observed worm intensity of c. 8000 worms.…”

Section: Discussionmentioning

confidence: 99%

Faecal egg counts provide a reliable measure of Trichostrongylus tenuis intensities in free-living red grouse Lagopus lagopus scoticus

Seivwright

Redpath²,

Mougeot³

et al. 2004

J. Helminthol.

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The reliability of different egg counting methods for estimating the intensity of Trichostrongylus tenuis infections in red grouse, Lagopus lagopus scoticus, was investigated in the autumn, when grouse may harbour high parasite intensities. Possible limitations to the use of these methods were also examined. Faecal egg counts were found to accurately estimate T. tenuis worm intensities, at least up to an observed maximum of c. 8000 worms. Two egg counting methods (smear and McMaster) gave consistent results, although the exact relationship with worm intensity differed according to the method used. Faecal egg counts significantly decreased with increasing length of sample storage time, but egg counts were reliable for estimating worm intensity for three weeks. The concentration of eggs in the caecum was also found to reliably estimate worm intensity. However, egg counts from frozen gut samples cannot be used to estimate worm intensities. These results conclude that, despite some limitations, faecal and caecum egg counts provide useful and reliable ways of measuring T. tenuis intensities in red grouse.

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“…Secondly, following infection with H. contortus, sheep with a high-burden infection appear to undergo a greater change in their faecal microbial community structure than to sheep with a low-burden infection (relative to their respective pre-infection microbiota). These observations are based on the premise that fecundity (faecal egg counts) correlates with worm burden, as has been consistently shown in H. contortus infections [28][29][30][31].…”

Section: Discussionmentioning

confidence: 99%

Variation in gut bacterial composition is associated with Haemonchus contortus parasite infection of sheep

et al. 2020

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Background: One of the greatest impediments to global small ruminant production is infection with the gastrointestinal parasite, Haemonchus contortus. In recent years there has been considerable interest in the gut microbiota and its impact on health. Relatively little is known about interactions between the gut microbiota and gastrointestinal tract pathogens in sheep. Thus, this study was undertaken to investigate the link between the faecal microbiota of sheep, as a sample representing the gastrointestinal microbiota, and infection with H. contortus. Results: Sheep (n = 28) were experimentally inoculated with 14,000 H. contortus infective larvae. Faecal samples were collected 4 weeks prior to and 4 weeks after infection. Microbial analyses were conducted using automated ribosomal intergenic spacer analysis (ARISA) and 16S rRNA gene sequencing. A comparison of pre-infection microbiota to post-infection microbiota was conducted. A high parasite burden associated with a relatively large change in community composition, including significant (p ≤ 0.001) differences in the relative abundances of Firmicutes and Bacteroidetes following infection. In comparison, low parasite burden associated with a smaller change in community composition, with the relative abundances of the most abundant phyla remaining stable. Interestingly, differences were observed in pre-infection faecal microbiota in sheep that went on to develop a high burden of H. contortus infection (n = 5) to sheep that developed a low burden of infection (n = 5). Differences observed at the community level and also at the taxa level, where significant (p ≤ 0.001) in relative abundance of Bacteroidetes (higher in high parasite burden sheep) and Firmicutes (lower in high parasite burden sheep). Conclusions: This study reveals associations between faecal microbiota and high or low H. contortus infection in sheep. Further investigation is warranted to investigate causality and the impact of microbiome manipulation.

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Population regulation in trichostrongylids of ruminants

Cited by 29 publications

References 41 publications

Effect of cattle grazing strategies and pasture species on internal parasites of sheep

Effect of cattle grazing strategies and pasture species on internal parasites of sheep

Faecal egg counts provide a reliable measure of Trichostrongylus tenuis intensities in free-living red grouse Lagopus lagopus scoticus

Variation in gut bacterial composition is associated with Haemonchus contortus parasite infection of sheep

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