A producer demonstration site from the NSW northern tablelands has highlighted the production benefits of improved worm control immediately following weaning.

Six members of the Tablelands Beef Group each grazed 20 worm-free heifers with 80 commercially drenched heifers to examine whether worms were reducing productivity levels despite the adoption of modern drenches and worm control practices.

The herds were monitored in the first year by comparing the growth of ‘worm-free’ heifers that were given repeated treatment with long-acting mectin drenches with heifers treated with the latest drenches and worm control practices.

As a result of this, in the second year a modified strategic drenching program applied at weaning was evaluated.

The major findings of these trials were;

• Undrenched weaner heifers were 60 kg lighter than the worm free weaners one year after weaning, while heifers drenched using normal commercial practice with short acting drenches were 30 kg lighter than the worm-free weaners at the same time.

• This difference had developed by six months of age suggesting that the developing immune system can effectively control worms after about 12 months of age.

• Improving worm control in the six months after weaning by a single treatment with a long acting mectin drench recouped these losses.

• While egg counts and plasma pepsinogen levels were elevated in worm affected heifers these indicators were low and would be difficult to use as predictors of the need to drench. Hence generic strategic drenching recommendations would be more useful for tablelands beef producers than tactical drenching following monitoring.

• No resistance to BZ or full dose ivermectin was noted but one herd had resistance to levamisole and two-of-two half dose ivermectin suggesting that producers should manage drenches to limit the development of resistance.

The results highlights the need for producers to control the impact of worms in the immediate post weaning period without compromising the effectiveness of the mectin drench family.

The PDS group advocated for further demonstrations of the use of other drench classes in combination with worm safe pastures.

The full report can be viewed here

Source: Meat and Livestock Australia