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Beyond the Bale : September 2019
ON FARM 39 ON FARM 39 That’s according to Western Rivers Veterinary Group partner, Dr Tim Gole, who undertakes flock pregnancy scanning for clients in Queensland and NSW. “An important question from producers is ‘what is a “normal” lamb marking result and how do you know if there is a fertility or other health issue impacting your flock’s productivity?’,” Dr Gole said. “Pregnancy scanning is essential to answering this question and I think of it as a measurement, management and forecasting tool. “Scanning data is important because if you’ve got great conception rates but a poor lamb marking result, you can quickly work out where the losses are occurring. This gives you a very different insight to just putting the rams in with the ewes and waiting until lamb marking to see the result. “The main benefit of scanning is the ability to identify the pregnancy status of ewes and allocating nutritional resources efficiently according to need. “Identifying the pregnancy status of ewes is a powerful management tool as it allows you to put in place measures to influence lamb survivability, which is directly related to birthweight and in turn, ewe nutrition. This is particularly important for twin-bearing ewes. “Every producer should be undertaking condition scoring at scanning time. It’s easily learnt and producers can undertake this themselves giving very cost-effective data collection. “If a twin-bearing ewe’s condition score is 2, her lamb survivability is likely to be quite low at under 50 per cent. However, if you take her up to a score 3, you can increase lamb survivability rates to well over 60 per cent. "Single-bearing ewes in condition score 2 are likely to achieve lamb survival of around 70 per cent, but this can increase to around 90 per cent by increasing condition score to 3. “Identifying your twin-bearing ewes and matching nutrition to their requirements is the best return on investment for feeding or pasture management.” CONTROL THE CONTROLLABLE Dr Gole said the best time to undertake pregnancy scanning is 90 days after the rams go in. This gives the most accuracy as the oldest lambs are about the size of a can - any bigger and the soundwaves can't see if there is more than one lamb. “Knowing the pregnancy status of a flock is an effective risk management tool because if you’ve had a really poor joining, it’s better to know 90 days after the rams went in than 150 or 170 days after,” Dr Gole said. “If you get a poor scanning result, you can work your way back from scanning to assess the likely impacting factors. “There are a number of factors to consider, and the first should be condition score. Comparing the score of each ewe at scanning to their score at joining can yield valuable insights. “Producers should also look at nutrition because there’s a direct correlation between nutrition and conception rates. “External factors can also play a role, so review the calendar and examine climatic conditions at joining, particularly heat.” Dr Gole said producers should also look at their ram team and investigate any possible diseases that can impact fertility, such as ovine brucellosis. Pre-joining ram examinations should be undertaken 12 weeks before joining. If Having the ability to assess the pregnancy status of ewes is a key tool for sheep and wool producers to not only help inform management decisions, but also create their own flock scorecard and identify any problems early. producers are achieving good scanning results but a low lamb marking result, disease testing can be undertaken. Key diseases behind lamb losses and late abortions can include ovine vibriosis, a campylobacter infection; toxoplasmosis, which is associated with feral cats; and pestivirus. SETTING BENCHMARKS Dr Gole said scanning data helps producers set their own benchmarks. “When you start generating data from your own flock it’s always a challenge, particularly for wool producers, to identify what’s normal for your flock,” Dr Gole said. “You’ve got the classic rubber band – there’s reproductive performance on one side and wool production on the other. If you select constantly for heavy wool cutting sheep, it sometimes comes at the expense of reproductive performance. “That’s why I think generating your own results is beneficial because it allows you to compare like with like and set benchmarks. “At scanning time, you can look to budget and do cost-benefit analysis and see where big gains can be made. “There were studies done at Trangie Agricultural Research Centre that found a massive difference between the top 25 per cent and bottom 25 per cent in terms of your flock, and the big difference came in the number of lambs reared as wool production remained relatively stable. The research found a $436 difference in lifetime value, with most of that figure based on net reproduction rates. “For the data it gives you, it’s rewarding. There has been some really big uptake of pregnancy- scanning programs in western NSW, because lamb production as sale of offspring makes up such a significant proportion of income now.” The two articles on this double page spread were originally published in ‘Flock Talk’, a publication by Leading Sheep, AWI’s grower extension network in Queensland. DATA UNDERPINS FLOCK SCORECARD Dr Tim Gole, Western Rivers Veterinary Group, teaching vet student Andrew Pegg about scanning.
In the Shops - September 2019