HOW TO USE THIS ONLINE MAGAZINE
by clicking the arrows at the side of the page.
by clicking anywhere on the page. A slider will appear, allowing you to adjust your zoom level.
and move the page around when zoomed in by dragging the page.
and return to the original size by clicking on the page again.
by entering text in the search field and click on "In This Issue" or "All Issues" to search the current issue or the archive of back issues
a PDF of this magazine.
by clicking on thumbnails to select pages, and then press the print button.
a page via email, Facebook, Twitter and more.
TO VIEW PREVIOUS EDITIONS
, click the
button at the bottom of the screen.
Beyond the Bale : September 2012
40 ON-FARM Goondiwindi vet Dr Mike Rival sees many Merino woolgrowers fail to maximise the number of lambs on the ground through a lack of attention to ewe selection and nutrition. The old adage of breeders to breed 'one good lamb' is faulty, Dr Rival says. If 10 per cent of ewes in a flock are dry that leaves 90 per cent to lamb, and when you factor in the average loss of 10-15 per cent of ewes failing to rear all lambs, the woolgrower is left with a 70 per cent lambing. NSW woolgrower John Hickson has carried on the work of his father Darvall, at the 20,000 acre 'Eural' property at Boomi near the Queensland border, in selecting ewes that bear and rear twins. In a good year he marks 130 per cent lambs in adult ewes and in an ordinary year, 105 per cent. In his country in northern NSW, the easy part is getting ewes to conceive lots of lambs. The hard part is getting them to rear those lambs. Mr Hickson says with good management it's possible to raise 80 per cent of lambs in a twin bearing flock, but with poor nutritional management this can easily drop to only 50 per cent survival of twin born lambs. When over 50 per cent of ewes conceive twins in his flock, this is the difference between a good and an average lambing. And he's found that the family's 40 years of selecting for fertility and rearing ability has had an unexpected spin-off -- improved mothering ability in Merino ewes. FAST FACTS l The AWI-supported Bestprac program has released a case study of northern NSW woolgrower John Hickson who uses pregnancy scanning to select ewes that bear and rear twins. l In a good year Mr Hickson marks 130 per cent lambs in adult ewes and in an ordinary year, 105 per cent. l As well as scanning, he has a focus on nutrition, condition score and combating predation to lift lambing percentages. THE CHALLENGE According to Dr Rival, the key challenges to lifting lambing percentages are: l the condition of ewes at joining and lambing l predators such as foxes and pigs l seasonal conditions at lambing time l labour costs that may prohibit pregnancy testing l selecting the optimal time for joining, to ensure either maximal lambs born or at the best time, with respect to predicted feed reserves. John Hickson says knowing the pregnancy status of ewes: l makes stocking decisions easier -- dry ewes are sold and he knows what feed will be needed at lambing l ensures reasonable birth weights, since twin bearing ewes are split off and fed well l improves the economics of wool growing, since high culling rates for non-twin bearing sheep means more young sheep for sale, or they can be joined to meat sheep rams for prime lamb production. RESULTS The selection for twins at Eural begins after joining. In June a contractor runs the Hickson's 2200 ewes through a VE machine to scan for pregnancies. Maiden ewes are no longer tested as their twinning rate is usually as low as 20 per cent. John Hickson says the low protein feed in their summer rain environment doesn't allow the young sheep to be in good enough condition at their first joining. He believes targeted supplementation of the maiden ewes prior to joining could be very worthwhile. Nutrition is also the key to ensuring that pregnancies translate into live lambs, particularly in the final trimester to ensure reasonable birth weights. Twin bearing ewes need to be above a condition score of 3.2 to maximize lamb survival. For single bearing ewes 2.5 is probably enough, he says. However, condition scores at lambing of above 4 for single bearing ewes actually leads to lower lamb survival due to dystocia or birthing difficulties from lambs that are too big. September 2012 BEYOND THE BALE Select twin bearing Woolgrower John Hickson (left) and vet Dr Mike Rival (right), conducting ewe pregnancy scanning at 'Eural', NSW in June 2012.