Parasite Management Project - Monthly Update - July 2019

Lamb performance rocketed since change of wormer

David Lewis of Halghton Hall near Wrexham has already seen a significant impact of being part of this project. When we asked him to test lambs more regularly during July the answer we received was -

“We don’t have many lambs here to test! There are only 100 lambs left and they are on clean ground. Since we changed to a yellow wormer for the first dose based on FEC results and your advice the lambs have just flown, and most have been sold as finished lambs by the end of July”.

Before we take all the plaudits, David did stress that a few other things have changed with more new reseeds on the farm, better grass growth this year and the influence of performance recorded sires becoming more dominant. But he does believe that getting a better control of worms was the last key that unlocked the farm’s potential.


So, what has changed?

  • As highlighted in May’s report we recorded high strongyle counts in David’s lambs
  • White wormer was normally used as it was Nematodirus season
  • As suspicious of white wormer’s resistance in strongyle species of worms, David was advised to use a levamisole wormer (yellow 2LV) instead.
  • Only 100 lambs left to finish at end of July versus 400 lambs last year (which sold Oct – Jan).
  • Likelihood is that the high strongyle challenge which was present early in the season wasn’t being controlled by the routine white wormer in previous years (even if used multiple times) and was holding back lamb performance.
  • The other big change – far less worming. Historically, most lambs would have had 2 or 3 doses of white wormer before selling, and later lambs would also receive Cydectin at weaning. To date only that one dose of yellow wormer was given – and only 100 lambs left on the farm!

Other FEC Results-

FEC challenges have been low to moderate over the last month or so for most lamb groups tested. This is highlighted by multiple tests Hywel Davies completed at the end of the month (last wormed 16th June). These were weaned around the end of July and only 2 groups out of the 5 tested needed worming; normally all lambs would have been treated at weaning. A close eye will need to be kept on FEC after weaning as the ‘weaning check’ may cause a drop in immunity.


FEC Results from Hywel Davies, Celyn Mawr