Effect of herbage species on gastro-intestinal roundworm populations and their distribution

Abstract

Sheep faeces containing strongylate eggs were applied to plots of perennial ryegrass, prairie grass, or chicory mixed with white clover, or lucerne without white clover. Plots were later harvested within four height zones and the herbage mass, numbers, and species of gastro-intestinal nematodes determined. Ryegrass, prairie grass, and lucerne plots produced similar yields of herbage dry matter (DM) (3580, 3180, and 3230 kg DM/ha respectively), whereas chicory produced 2250 kg DM/ha. Ryegrass-, prairie grass-, and chicory-based swards had similar proportions of herbage DM within each height zone, the quantities declining with increasing height. Lucerne swards had less DM in the central height zones than other swards but proportionally more above 125 mm from ground-level. Larvae from 0.73% of eggs were recovered, but the rate was influenced by herbage species. The grass-based swards had higher larval populations than had lucerne or chicory, and lucerne had more than chicory. Larval density tended to be higher in the 26-75 and 76-125 mm zones than in the 0--25 and greater than 125 mm zones, which were similar. Chicory swards offered the best opportunity to reduce larval intake in grazing animals as they had the lowest populations per unit of herbage mass. This was, however, associated with a lower herbage mass. A92043Lucerne offered low larval popUlations together with high nutritive value and herbage mass making it a highly suitable forage for growing lambs.

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

“…The purpose of the present experiment was to ascertain the larval population within the expected lamb grazing zone, hence the cutting height and interval selected. Increasing the sward density increased the number of larvae recovered from herbage, and this concurs with the findings of Moss & Vlassoff (1993) when they compared various pasture species that generated differences in sward density. They, and Knapp (1964), concluded that denser swards created more favourable microclimates for the development and survival of trichostrongylid larvae.…”

“…In the present experiment, had herbage been cut to ground level, it is likely more larvae would have been recovered, as according to Vlassoff (1982), more exist nearer ground level. However, this would not necessarily have yielded more per kg of DM as Moss & Vlassoff (1993) found the concentration of larvae was lowest in ryegrass swards within 0-25 mm of ground level compared to higher zones. The purpose of the present experiment was to ascertain the larval population within the expected lamb grazing zone, hence the cutting height and interval selected.…”

“…Differences in sward density between pasture species were considered by Moss & Vlassoff (1993) to be the most likely cause of the differences between pasture species in larvae numbers observed.…”

“…Using different pasture species offers a means of influencing the microclimate within the sward and therefore the larval population (Moss & Vlassoff 1993;Niezen et al 1998), and the number ingested by grazers (Knapp 1964;Scales et al 1995).…”

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

“…Moss & Vlassoff (1993) found that ryegrass-and prairie grass-based swards contained more nematode larvae than did lucerne, which in turn contained more than chicory. A similar observation was made by Scales et al (1995) in a lamb grazing experiment which compared a pasture with low endophyte ryegrass, cocksfoot, and tall fescue with a pasture containing lucerne and chicory.…”