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Victoria worm update - August 2013

Andrew Whale, Livestock Logic, Hamilton (a.whale@livestocklogic.com.au)

It has been a very wet August so far for the South West which is pleasing to see with properties now starting to get substantial run off. My CliMate app tells me as of 23rd August we are on track for wettest August on record. While it would be nice to see some nice sunny weather shortly, the lack of rain from September onwards last year is still firmly in most people’s mind.

On the worm front things have been pretty steady and we have not seen the incidence of mortality that we saw in the corresponding period last year. This is somewhat of a surprise as there are some light conditioned sheep in South West Vic. The low mortality rates are attributable to the hot, dry extended summer that has been helpful to eliminate pasture worm burdens. With effective summer treatments where needed, producers were able to start this autumn with minimal worm burdens in stock and on pastures.

Until food on offer improves significantly in late September we need to continue to monitor lambs every 2-3 weeks and mature sheep monthly to ensure production is not limited in sheep mobs.

We have only seen a slight increase in worm counts in August as opposed to July. The Livestock Logic WEC lab stats again paint a useful picture

  • Mobs requiring a drench after WEC
    • Weaners          24%
    • Maidens          34%
    • Mature             22%

Maiden ewes are the highest group of sheep represented; we put this down to their higher demands with late gestation/lactation while not having the acquired immunity and body condition score levels of older age group ewes.

Interestingly we had 25% of mobs with a WEC greater than 200 but only 2% with above 600 epg. This shows that most of our clients are getting WEC’s done well before animals are getting a big production setback. Obviously this is the aim of worm egg counts, but not always achieved.

Quick plug for drench resistance testing

Table 1: Reduction in WEC to different treatment groups for most recent 5 properties we have done drench resistance testing on this month. 100% indicates total worm kill. If <95% reduction in WEC then classified as resistant to that chemical.

Properties

A

B

C

D

E

Ivermectin

96%

99%

 

72%

93%

Abamectin

100%

100%

86%

91%

100%

Moxidectin

100%

100%

16%

97%

99%

Naphthalophos/Ivermectin

100%

100%

99%

 

99%

BZ/Lev

99%

89%

100%

93%

96%

Nap/BZ/Lev

100%

99%

100%

100%

100%

Aba/BZ/Lev

100%

100%

99%

99%

100%

 

Briefly what we can see looking at each property

A - All drenches effective but emerging resistance to Ivermectin

B - Resistance to BZ/Lev combination only

C - Resistance to Abamectin and moxidectin

D - Resistance Ivermectin, Abamectin, BZ/Lev combination

E - Resistance to Ivermectin and emerging resistance to BZ/Lev

 

This shows the importance of drench resistance testing as the variation between properties is massive. There is no way of predicting what drenches are effective without testing on each property.

We urge all producers to perform a drench resistance test every 3 years so a drench plan can be developed. It is a worthwhile investment considering the annual costs spent on drench products.