Effect of sward density and size of faecal deposit on the development and persistence of third‐stage Trichostrongylid larvae of sheep

Abstract

Ryegrass swards of low and high density were established to which lamb faeces containing nematode eggs were uniformly applied. This was done as either large or small deposits with all plots receiving the same quantity. Herbage was cut at 15 mm above ground level on five occasions over the following 29 weeks and nematode larvae extracted. The lower sward density plots produced less dry matter during the first 12 weeks after establishment but subsequently out-yielded those sown at the high density. When assessed over 36 weeks post-sowing, initial density had no effect on production. Overall, larval recovery equated to less than 0.5% of eggs applied. Numbers peaked between 67 and 147 days after application then declined and were extremely low by Day 200. Compared to low density, high density swards yielded the highest number of larvae overall. Sward density during the first 67 days after faeces were deposited had a greater effect on larval development, survival and persistence than subsequent differences in sward characteristics. The larger faecal deposits resulted in higher numbers of larvae. Effects of increasing sward density and faecal deposit size were cumulative.

Prevalence and on-farm risk factors for diarrhoea in meat lamb flocks in Western Australia

“…Rainfall events reported across the south-west land division in early July, mid and late August 2010 (Australian Bureau of Meterology, 2011b), were likely to have contributed to increased pasture growth, increased distribution of strongylid nematode larvae over pasture and increased surface water run-off from pastures into dams, rivers and creeks. Climatic conditions during August and September are also favourable for the survival of infectious parasite stages, including strongylid nematode third stage larvae (Dobson et al, 1990;Marley et al, 2006;Moss and Bray, 2006) and Cryptosporidium, Giardia and Eimeria (oo)cysts (Robertson et al, 1992;Fayer et al, 1996). The actual (observed) annual rainfall across the survey region was below average during the 2010 survey period (Fig.…”

Effect of herbage species and renewal technique on the free living stages of gastro-intestinal roundworms

“…This herbage type effect may reflect the greater density of the grass-based swards, a factor shown by Knapp (1964), Moss and Vlassoff (1993) and Moss and Bray (2006) to affect larval populations on herbage. However, both the new pasture and pasture following brassica contained considerably more clover (average 23%) than did old pasture (1%) or pasture following barley (4%).…”

“…and Teladorsagia spp. were detected on herbage up to 26 weeks following an autumn contamination, with the peak occurring after 10 weeks (Moss & Bray 2006).…”

“…According to Familton & McAnulty (1996), more than 90% of the endoparasites in sheep systems in New Zealand are located within the pasture and soil environment. Factors known to have a major effect on populations within a sward include moisture, humidity and temperature (Anderson et al 1970;Todd et al 1976 within a sward can be affected by sward density (Moss & Bray 2006) and pasture species (Knapp 1964;Moss & Vlassoff 1993).…”

Effects of Stocking Rate and Heather Supplementation on Gastrointestinal Nematode Infections and Host Performance in Naturally-Infected Cashmere Goats

“…In general, a higher stocking rate means higher GIN egg output and dispersion and therefore higher pasture contamination and infection risk. In addition, mountain pastures have a higher density than those in lowlands, and the development and persistence of third-stage trichostrongylid larvae is higher in denser pastures (Moss and Bray 2006). A high stocking rate also means a shorter palatable sward height, less options to select grazing areas when rejecting those contaminated by feces, lower intake, and even negative nutritive balances (Morley and Donald 1980).…”