Omega-3 and Omega-6 Fatty Acids in the Diet Can Alter Offspring Sex Ratio - Grain for Girls, Fish for Boys?

in environment, medicine, biology

Can maternal diet influence offspring sex ratio?  According to a research report from New South Wales (Australia) Department of Primary Industries, ratio of omega-6 to omega-3 fatty acids in the diet of mother has a profound effect on offspring sex ratio. 

Lambs fed with a diet rich in omega-6 fatty acids gave birth to more female offspring whereas diet rich in omega-3 fatty acids resulted in an increased number of male offspring.

The research at Wagga Wagga (New South Wales) revealed that diet may affect the sex ratio of lambs by up to 15 per cent and this may lead to a breakthrough in sheep reproduction, NSW Department of Primary Industries (NSW DPI) research leader Dr Ed Clayton said.

“The results are the exciting culmination of a number of years work and have the potential to change the way producers' manage reproduction in ewe flocks,” Dr Clayton said.

The research, which is being carried out through the EH Graham Centre, an alliance between Charles Sturt University (CSU) and NSW DPI, recently received a funding boost of $310,000 from Meat and Livestock Australia across a two-and-a-half year period.

The research is being undertaken by CSU Ph D student Catherine Gulliver and involves the study of 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.


Ph D student Catherine Gulliver feeding ewes
taking part in the trial at Wagga Wagga.

Ms Gulliver is the recipient of a scholarship from the Australian Postgraduate Award scheme and the Future Farm Industries Cooperative Research Centre.

Omega-3 and omega-6 fatty acids are known as polyunsaturated fatty acids.  They have been reported to regulate skin growth, bone mass, muscle and energy metabolism. A healthy diet contains a balance of omega-3 and omega-6 fatty acids.  It has also been reported that consumption of omega-3 fatty acids lowers inflammation and may reduce the risk of coronary heart disease. However the role of omega-3/omega-6 ratio in altering sex ratio of the offspring is an emerging concept.

A recently published study by another group have provided evidence that maternal diet, in the form of increased amounts of rumen-protected poly-unsaturated fatty acids fed around conception, rather than maternal body condition, can skew the sex ratio towards males.

Dr Clayton said the research was conducted in open-air pens at the Wagga Wagga Agricultural Institute and involved 300 first-cross ewes split into two groups.

“The first group was fed omega-6 sourced from oat grain (now fondly referred to as 'grain for girls') and the second group was fed omega-3 sourced from a diet of pea silage,” Dr Clayton said.

“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, and we identified a 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."

“We were very surprised that the different diets could have such a profound influence on the sex of lambs."

“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."

“Alternatively, if producers wanted more male lambs (castrated male lambs develop more quickly and have more muscle) for prime lamb production systems, they might consider feeding a diet high in omega-3 at joining.”

Dr Clayton said a further trial now underway, involving 300 first-cross ewes and 320 Merinos, focuses on whether the skewing effect was pre or post-conception and if the effect is similar in first-cross ewes and Merinos.

According to the report from NSW, results from this trial will be available in mid 2013.

Source: This article is based on a news release (August 16, 2011) from New South Wales Department of Primary Industries.  Photo provided to by the NSW DPI.

Other references used:
De Spirt S, Stahl W, Tronnier H, Sies H, Bejot M, Maurette JM, Heinrich U. Intervention with flaxseed and borage oil supplements modulates skin condition in women. Br J Nutr. 2009;101(3):440-5.

Watkins BA, Hutchins H, Li Y, Seifert MF. The endocannabinoid signaling system: a marriage of PUFA and musculoskeletal health. J Nutr Biochem. 2010;21(12):1141-52. Epub 2010 Oct 8.

United States Food and Drug Administration . FDA announces qualified health claims for omega-3 fatty acids. Press release. (September 8, 2004)Retrieved Aug 29, 2011.

Green MP, Spate LD, Parks TE, Kimura K, Murphy CN, Williams JE, Kerley MS, Green JA, Keisler DH, Roberts RM. Nutritional skewing of conceptus sex in sheep: effects of a maternal diet enriched in rumen-protected polyunsaturated fatty acids (PUFA). Reprod Biol Endocrinol. 2008 Jun 9;6:21.

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