What type of worm laid those eggs? Faecal egg counts tell us how many worm eggs our stock are passing. Larval cultures or GIN PC tell us what worm the eggs are from.
Larval cultures
Larval cultures are normally done at an animal health laboratory. Eggs are incubated and hatched out; the resulting larvae are identified under a microscope. Larval cultures identify worms to the ‘genus’ level (not ‘species') – e.g. Trichostrongylus worms are reported as ‘Trichstrongylus’, not ‘T colubriformis’ or ‘T vitrinus’.
Doing a larval culture on poo samples after a FEC can be useful to understand whether the FEC is mostly made up of ‘nasty’ worms such as Haemonchus or Trichostrongylus, or whether it’s more of a mixture.
Larval cultures are an important part of drench checks and faecal egg count reduction tests, to help us understand which worm types are surviving our drench treatments.
There is very high variability in larval culture results and care must be taken not to overinterpret the absolute numbers.
GIN PCR
GIN PCR is a DNA based test which is done at an animal health laboratory. This test amplifies up genetic material from worm eggs in the faeces. GIN PCR can detect down to species level for all the important parasite species affecting sheep and cattle. This test can identify worms to the ‘species' level– e.g. Trichostrongylus worms are reported as ‘T colubriformis’ or ‘T vitrinus’.
Whether you’re using GIN PCR to monitor Barber’s Pole pre‑tup or to identify which parasites may have survived a drench during a drench check, this test provides results within a few days.
For cattle, Ostertagia can be detected before they show up in an egg count, enabling targeted drench decisions to be made before calf performance drops.