Ewe need more greens if boys are on your mind


Aus­tralian sci­en­tists may have cracked the holy grail of an­i­mal farm­ing, dis­cov­er­ing how to markedly ma­nip­u­late the sex ra­tio of lambs.

Re­searchers at Wagga work­ing with lo­cal sheep farm­ers in the NSW Rive­rina, have found that adding two hand­fuls of oats or grain a day to the pad­dock diet of fe­male sheep for four weeks be­fore they are mated with a ram, can cause up to 70 per cent of the re­sult­ing lambs to be born girls.

In stark con­trast, leav­ing the ewe flock in a pad­dock eating only grass led to a much higher num­ber of boy lambs be­ing born five months later, with the lusher and greener the grass or lucerne avail­able at the time of con­cep­tion pro­por­tion­ally boost­ing the ra­tio of ram lambs born.

Ed Clay­ton, se­nior an­i­mal nu­tri­tion­ist with the NSW Department of Pri­mary In­dus­tries at Wagga, said the early re­sults and field tri­als looked promis­ing, with wool­grow­ers of­ten pre­fer­ring to have more fe­male lambs to build and ex­pand their breed­ing flocks and boost ge­netic ad­vances.

But some farm­ers pre­fer more male lambs, as they grow faster and reach a weight at which they are ready for eating quicker, or they may op­er­ate a merino stud sell­ing adult rams for breed­ing.

Dr Clay­ton said it ap­peared that the Omega-3 fatty acids in green grass fed to the ewes just be­fore mat­ing — also found in salmon, oily fish, nuts and green veg­eta­bles — was re­spon­si­ble for more male lambs be­ing born.

Oats and most ce­real grains — as well as eggs — are high in Omega-6 fatty acids, which seem to de­liver more fe­male off­spring.

Dr Clay­ton ac­knowl­edged there were po­ten­tial im­pli­ca­tions for hu­mans in his ground­break­ing re­search, which re­in­forces other find­ings that the diet of the pro- spec­tive mother at the time of con­cep­tion can in­flu­ence the gen­der of the child.

He said it was still too early in his sheep feed­ing tri­als to em­phat­i­cally sug­gest a woman want­ing a baby boy should drink lots of green kale smooth­ies and eat salmon while try­ing to be­come preg­nant, while a woman des­per­ate for a girl should stick to muesli, rolled oats and por­ridge.

On his Hol­brook sheep prop­erty, prime lamb pro­ducer Tim Trescowthick has watched Dr Clay­ton’s nearby tri­als with fas­ci­na­tion, be­liev­ing that if farm­ers had the abil­ity to ma­nip­u­late or shift the sex ra­tio of their lambs in dif­fer­ent sea­sonal con­di­tions, it would be a very use­ful and flex­i­ble man­age­ment tool.

“In some years, I would be seek­ing more male lambs be­cause they grow faster and are ready for mar­ket ear­lier, while af­ter a drought I might be want­ing more ewe lambs if I was re­stock­ing and re­build­ing my flock num­bers,’’ he said.


Lamb pro­ducer Tim Trescowthick with his flock of sheep on his Roach­dale prop­erty near Hol­brook, in south­ern NSW

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