Smart grazing tips for merino weaners.

Smart grazing is an improved, yet simple and reliable, strategy for the control of worms in weaner sheep during their first winter.

The why and how of 'Smart Grazing'
Merino weaners are very susceptible to worms in their first winter. Consequently, they need to graze pastures that have as few worm larvae as is practicable. 'Smart grazing' combines intensive grazing for 30 days with each of the two 'summer' drenches to ensure that virtually no worm eggs are deposited on a chosen pasture from the first summer drench until after the autumn break when the weaners are put into these pastures.

Intensive grazing means using 2.5-3 times the normal stocking rate, for no longer than 30 days after each of the summer drenches is given. Not exceeding 30 days is critical because it takes three weeks for a worm larvae (eaten off pasture) to develop into an egg-laying adult in the sheep. After the intensive grazing period, the paddocks are de-stocked to allow the pastures to re-grow. This means that the total stocking pressure for the 'Smart grazed' paddock will be the same as that for a paddock continuously stocked at the farms normal stocking rate.

Tips for Drench Resistance - Worm Management

Worm management

The 4 key principles of worm management everywhere:

1. Do regular worm egg counts

2. Know your drench resistance status

3. Maximise non-chemical worm management

4. Seek professional advice

What Causes Drench Resistance?

• Drench resistance is caused by exposing worms to several treatments of same drug
• This can kill susceptible worms but leaves increasing numbers of resistant worms
• The resistant worms are genetically different to susceptible worms
• Resistant worms pass on their resistance to future worm generations
• The practice of drenching sheep onto clean pastures with drenches that are not 100% effective leads to the rapid development of resistant worm populations.

How Quickly Can Drench Resistance Develop?

The rate of development of drench resistance is influenced by factors including:

• The chemical group and persistency of the product involved
• The frequency of treatments
• The timing of treatments
• The worm species involved
• Environmental factors

 ·         The earlier you detect resistance, the EASIER IT IS TO MANAGE

·         UNNECESSARY DRENCHING is the major cause of drench resistance

There are several effective non-chemical ways to control worms.

Some management tools are:

• Cross-Grazing with Cattle;
• Buying Rams from studs that breed sheep resistant to worms;
• Using “Smart Grazing”;
• Managing Nutrition to help sheep develop resistance to worms.

Strategic Dosing - Sheep and Goats

                                   

As winter approaches in South Africa many farmers believe that the worm problem associated with the humid and often hot summer months will be drastically reduced with the decreasing temperatures. 

While this may be true, winter is not without its worm challenges. This said, flukes (conical and liver flukes), roundworms (Brown stomach worm, Bankrupt worm (Long necked), White bankrupt worm, over wintering roundworm and nasal bots larvae’s are some of the worm burdens your stock has to deal with during the winter period.

 There is increasing recognition that larvae arrest in development as a result of prior experience of certain climatic or seasonal influence, a phenomenon referred to as hypobiosis.  Low or zero egg counts in winter is therefore no assurance that there exists a low or no worm burden. These hypobiotic larvae will continue from their arrested development when favourable environmental conditions ensue:

     ·         During the next spring or,

    ·      When host (ewe) immunity around the next lambing time is reduced – a “normal” occurring phenomenon that we need to manage. 

Winter is also a critical time for ewes, most of whom are pregnant during a period often characterised by poor grazing quality and harsh weather conditions. Ewes are required to maintain and grow the foetus inside them – especially during the last third of pregnancy. Closer to term, there is an increased nutrient requirement towards formation of colostrum. An increased winter worm burden will, despite improved nutrition, erode on the ewe’s body condition (fat reserves), increase the risk of poor oöcyte (egg) quality and conception, decrease the quality of colostrum and put the newborn at risk. Additionally, anaemia, poor growth and diarrhoea are also seen in winter due to worm problems.

The fact pointed out above should make “pre-winter strategic dosing” an essential component of any farm’s integrated parasite management (IPM) system. Farms applying a “before winter strategic dosing” dose all their animals usually in May, after the frost, when there is little or no re-infection of the animals from the pasture. 

Using the correct remedy, pre-winter strategic dosing should achieve the following:

• Eliminate nasal bot larvae in the sheep when there are no longer free living flies around that lead to re-infestation. Pre-lambing dosing against nasal bots is important as we need to ensure that the ewe can identify her lamb after birth by olfactory means. Similarly, rams are more efficient in detecting ewes in oestrus when nasal cavities are free of bots and the mucus secretion this infestation causes    
• Remove hypobiotic roundworm larvae (positive egg count is therefore not a requirement for dosing).