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Optimising ewe, lamb and heifer calf performance over summer

Optimising ewe, lamb and heifer calf performance over summer

Optimising ewe, lamb and heifer calf performance over summer

PGG Wrightson’s Animal Production Technical Team, comprised of Laura Pattie, Andrew Dowling and Jason Leslie, are experienced veterinarians. Through technical support and training, they pass their knowledge to our national network of Technical Field Representatives.

We've asked Andrew, Jason and Laura to share their thoughts on how to optimise ewe breeding performance and improve lamb and heifer calf growth rates this summer.



With sheep production an area of special interest for Andrew Dowling, PGG Wrightson Technical Expert – Animal Production, here he discusses ewe health in readiness for tupping.

“Prioritise getting all ewes in body condition score 3 or more by tupping as this has a significant influence on their mating and weaning performance,” says Andrew.

To achieve this, Body Condition Score (BCS) ewes, so those requiring preferential feeding are identified at weaning or shearing. Andrew says placing your hand on the ewe’s back to BCS will find ewes at BCS 2.5. “These ewes are an easy win that might otherwise be missed if only condition scoring by eye. The better condition the ewe is in at tupping, the more likely she’ll retain that condition at lambing.”

Once the number of low BCS ewes is known, the number of other animals able to be fed on-farm can be calculated. Ensuring these ewes are fed well, Andrew says, may mean some lambs need to be sold.

To increase the BCS of lighter ewes Andrew suggests, “grazing low BCS ewes in the same rotation as lambs. This will provide the ewes with high-quality feed, help maintain pasture quality for the lambs as well as the ewes consuming the majority of worm larvae.”

When considering feed choice, Andrew suggests offering ewes high-quality green pasture or forage, grazing above 1,200 kilograms (kg) of dry matter. If conditions are dry, consider supplementary feeding with grains, compound feeds (meal or nuts), summer forages or silage.

While preferentially feeding lower BCS ewes, Andrew says to use the ewes in good condition to clean up rough pasture. By doing so by autumn, the pasture will be ready to grow in spring ready for new season lambs.



For Jason Leslie, PGG Wrightson Technical Expert – Animal Production, seeing production animals achieving their genetic potential is what motivates him. Jason shares how to optimise lamb growth rates over summer on a breeding and finishing farm.

Knowing when to wean is important says Jason. The ideal time is when milk supply has dropped and competition from the ewe for high-quality pasture becomes detrimental to the lamb.

Post-weaning, the quality and quantity of forage consumed is the biggest driver of Lamb Liveweight Gain (LWG) according to Jason. Whether it’s pasture-based or crops such as lucerne or clovers, on average over summer, most lambs only achieve 100 grams per day LWG on dryland pastures.

This is due to lower Metabolisable Energy (ME), dropping protein levels and the higher fibre content of pasture.

To achieve high growth rates, Jason recommends feeding forages with ME levels of 11 plus megajoules of ME and protein levels of 16 percent or better. He also recommends a 28-day preventative drench programme to clear the lamb of adult worms and eliminate worm egg output for 21 days, reducing pasture larval challenge over time.

With widespread drench resistance, research shows a reduction of lamb value of 14 percent occurs with the use of ineffective drenches¹, due to poor feed conversion efficiency and lower carcass weights. Jason says to avoid this, complete a post-drench check to determine drench efficacy and reduce larval challenge by cross-grazing with cattle. Refugia can be achieved with undrenched ewes grazing behind lambs.

By targeting high daily LWG, Jason says more lambs can be finished earlier, having consumed less total feed, leaving more feed for ewes leading up to mating.



Having grown up on a dairy farm, Laura Pattie, PGG Wrightson Technical Expert – Animal Production has always been surrounded by animals and cared for their wellbeing.

Heifer calves, Laura explains, are the future of a herd so it is important to focus on their growth rates during the warmer months when pasture quality often declines.

Common challenges in summer include poorer pasture quality and worm challenges which can impact on the immediate and future growth of the calves.

To help manage worms, Laura suggests using an effective drench programme, conducted at intervals best suited to the farm system, along with providing nutritious feed. Laura says cross-grazing calves with adult cattle also helps manage worm burden.

Begin a worm drenching programme four to six weeks after calves have been consuming pasture, which Laura says is usually at 10 to 12 weeks of age. She points out, when calves are less than 100 kg liveweight, it is safest to use an oral oxfendazole/levamisole double combination drench. As the calves reach 100 kg liveweight or over, switch to a triple combination oral drench.

As coccidiosis and yersiniosis often occur at stressful times such as weaning, Laura recommends continuing to feed calf meal for four to six weeks after milk feeding has stopped. Select a calf meal that contains a coccidiostat and ensure at least one kg of meal per calf per day is consumed to ensure an adequate intake of the coccidiostat. Calf meal also boosts the calves’ energy and nutrient intake while their rumens are still developing the ability to consume large amounts of pasture or forage.

To provide calves’ with high-quality feed over summer in areas prone to dry conditions, Laura recommends using specialist summer forages, such as chicory or brassicas, so calves receive adequate energy and protein to support good growth rates.

Summer brings feed and health challenges for stock. Contact your local PGG Wrightson Technical Field Representative to discuss a suitable animal health and nutrition programme for your farm.

1 Sutherland, I.A., Shaw, J., & Shaw, R.J. (2010). The production costs of anthelmintic resistance in sheep managed within a monthly preventive drench program. Journal of Veterinary Parasitol 171 (3-4), 300-304.