Diet may af­fect gen­der

Shepparton News - Country News - - COBRAM HORSE TRIALS -

Sheep pro­duc­ers may soon have the abil­ity to in­flu­ence the sex ra­tio of lambs by ma­nip­u­lat­ing ma­ter­nal nutri­tion around the time of con­cep­tion, with new re­search in­di­cat­ing a sheep’s diet may in­flu­ence the gen­der of off­spring.

The re­search, con­ducted by NSW DPI in col­lab­o­ra­tion with the Gra­ham Cen­tre at Charles Sturt Univer­sity, started in 2010 and has in­volved more than 1500 ewes.

It ex­am­ines the ra­tio of omega3 and omega-6 fatty acids in the diet of ewes and the ef­fect it has on the sex ra­tio of lambs.

Ini­tial re­search re­sults found that feed­ing a diet high in omega3 (such as pas­ture and silage) to ewes at join­ing was associated with a higher pro­por­tion of male lambs, while a diet high in omega-6 (based on oat grain) pro­duced a higher pro­por­tion of fe­male lambs.

On-farm tri­als are now be­ing car­ried out by Ed Clay­ton from NSW DPI in con­junc­tion with the Hol­brook Land­care Network to test these find­ings, with fund­ing from Meat and Live­stock Aus­tralia and Aus­tralian Wool In­no­va­tion.

MLA pro­ducer con­sul­ta­tion and adop­tion gen­eral man­ager Michael Crow­ley said the re­search was pos­i­tive news for pro­duc­ers.

‘‘The ini­tial re­search looks promis­ing and field tri­als will de­ter­mine if pro­duc­ers can in­flu­ence the sex ra­tio to the pre­ferred gen­der to tar­get spe­cific pro­duc­tion sys­tems through chang­ing in­put man­age­ment,’’ Mr Crow­ley said.

Dr Clay­ton said work was be­ing un­der­taken on 11 trial sites over a three-year pe­riod to test the prac­ti­cal­i­ties of the re­search on farms near Wagga Wagga and Hol­brook, in south­ern NSW.

‘‘We are look­ing at how the ef­fect of feed­ing di­ets to un­syn­chro­nised ewes in a pad­dock feed­ing sit­u­a­tion in­flu­ences the sex ra­tio of the lambs, and the best sources of omega-3 and omega-6 to in­cor­po­rate into prac­ti­cal on­farm ra­tions,’’ Dr Clay­ton said.

The first of the on-farm tri­als be­gan last year and in­volved five farms with a sam­ple flock of 500 ewes split into two groups on each farm.

Half the ewes grazed on pas­ture alone in the lead-up to join­ing and the other half were sup­ple­mented with 600 g of oats per day for four weeks lead­ing up to join­ing and dur­ing the first two weeks of join­ing, giv­ing them six weeks of grain.

‘‘At the farm gate, the first year of tri­als didn’t show a huge dif­fer­ence in the sex ra­tio of off­spring on in­di­vid­ual farms,’’ Dr Clay­ton said.

‘‘On some farms there was a four to five per cent dif­fer­ence in sex ra­tio but other pro­duc­ers recorded no change.’’

How­ever, blood sam­ples col­lected from a rep­re­sen­ta­tive sam­ple of ewes from each treat­ment group found there was a cor­re­la­tion be­tween the fatty acid pro­file in the blood and the sex ra­tio of lambs.

Dr Clay­ton said the next two years of trial work would ad­dress some of the prac­ti­cal chal­lenges of manag­ing the feed­base and con­duct­ing un-repli­cated tri­als on-farm.

Nutri­tion tricks . . . Re­searchers are working out if you can de­ter­mine the sex of lambs by chang­ing the feed­ing regime of the ewes. Pic­ture: Holly Cur­tis

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