SHEEP breeding enterprises would undoubtedly benefit from the ability to skew the sex ratio of offspring towards their preferred gender.
NSW Department of Primary Industries research leader, Dr Ed Clayton, will give attendees at the Grassland Society of Southern Australia’s annual conference at Albury an update on ground breaking research that shows diet may well affect the sex of lambs.
The conference is being held on July 16 to 18 at the SS&A Club.
Dr Clayton said the research, which started in 2010 and has involved more than 1500 ewes, examines the ratio of omega-3 and omega-6 fatty acids in the diet of ewes and the effect it has on the sex ratio of lambs.
The work being carried out by the NSW DPI in conjunction with the Graham Centre, (an alliance between Charles Sturt University and NSW DPI) is being funded by Meat and Livestock Australia (MLA).
Dr Clayton said recent trials have examined whether the skewing effect was pre or post-conception and if the effect was similar in first-cross ewes and Merinos.
“We think at this stage that pre-joining has the most important effect on the sex of the lamb. However, there may be some additional changes with feeding post conception, but we are still doing work on that,” he said.
“We are keeping the female progeny and have set up a new trial, with additional funding from MLA, to see if there are any carry over effects of our feed regimes into the next generation that can affect the sex of lambs.”
The original research conducted at the Wagga Wagga Agricultural Institute involved 300 first-cross ewes split into two groups.
The first group was fed omega-6 sourced from oat grain and the second group was fed omega-3 sourced from a diet of pea silage.
Ewes were fed the two diets for six weeks prior to joining to Dorset rams and three weeks after joining.
After lambing, the lambs were tagged, which Dr Clayton said identified a surprising 15 per cent increase in the number of female lambs from sheep fed high omega-6 (grain) compared with those fed high omega-3 (pea silage) diets.
“For a self-replacing ewe flock or for first-cross ewe breeders, to increase the number of female lambs relative to the number of male lambs, a diet high in omega-6 could be fed at joining," he said.
“Alternatively, if producers wanted more male lambs (wethers develop more quickly and have more muscle) for prime lamb production systems, they might consider feeding a diet high in omega-3 at joining.”
