Article By: Country Wide Magazine. Source: Country Wide

Using chicory in a deer grazing system could be a potential tool to control internal parasites and reduce anthelmintic use on deer farms.

Massey University researcher, Nicola Schreurs (pictured at left) presented the results of two experiments funded by the Game Industry Board at the Society of Animal Production conference in July.

Schreurs' work was carried out as a joint project between Massey University and AgResearch. The work is a follow up to research in 1999 that found that undrenched weaner deer grazed on chicory grew faster and had lower faecal egg counts than similar animals grazed on perennial ryegrass/white clover. She focussed on the hatching, development and migratory ability of the larvae of internal parasite eggs and lungworm that had travelled through the digestive tracts of deer grazing chicory or perennial ryegrass/white clover.

In her first experiment she collected faeces of undrenched weaner deer to obtain internal parasite eggs and lungworm larvae from animals with parasite burden. The eggs were tested for their hatching ability, but there was no difference between the eggs from the faeces of deer that had grazed on chicory compared to the eggs from deer that had grazed pasture. But the lungworm development tests indicated that the lungworm from the faeces of chicory-fed deer had significantly fewer L2 larvae developing to the infective L3 stage compared to the larvae collected from the faeces of deer grazing pasture.

She says this shows promise that grazing chicory will actually reduce the forage contamination with infected larvae.

"Reduced numbers of infective larvae on grazed forages may lower the dependence on anthelmintics by providing 'safe' pastures."

In her second experiment, Schreurs again collected faeces from undrenched weaner deer, but also collected fluids from the rumen (first stomach) and abomasum (fourth stomach) from deer grazing on the two forages. The larvae from the faeces of chicory and pasture grazed deer were incubated in the rumen or abomasum fluids from the deer grazing the two forages and then tested for their ability to migrate. This indicated that L1 lungworm larval migration was most inhibited in the lungworm collected from the faeces of deer grazing chicory. Adding fluid from the deer grazing pasture to larvae collected from the chicory-grazed deer didn't reduce larval migration, but adding fluid from the deer grazing chicory to larvae collected from the deer grazing pasture did reduce larval migration.

Schreurs carried out a further test to indicate the role that condensed tannins (CT) were playing in inhibiting the larval development. This showed that CT in chicory could have been responsible for the inhibitory effect of rumen fluid, but the low pH of abomasum fluid means CT cannot chemically bind at this stage of the digestion process.