Maternal influence on the skewing of offspring sex ratio: a review

Abstract

Sex pre-selection of the progeny to suit the livestock production system aids in greatly increasing the efficiency and profitability of the livestock enterprise to meet the demand for animal meat and dairy products. Individual animals can skew the sex ratio in response to various social and environmental stipulations. These social and environmental factors include the composition of the maternal diet, maternal hormonal levels, maternal stress, and the time of insemination. Hence, this present review focuses on these approaches and their success rate as premises for the alterations of offspring sex ratio in different animal species. Numerous studies have linked maternal nutrition and its influence on offspring sex ratio. A maternal diet rich in calcium and magnesium favoured the production of more females, while diets rich in sodium and potassium favoured more males. Furthermore, feeding animals with a particular type of fat diet, including omega-3, omega-6, or omega-9 fatty acids, assists in sex pre-selection. The circulating hormone level in females during conception is associated with the skewing of sex ratio. In addition, maternal stress during the conception period is also found to be associated with the skewing of the sex ratio in favour of female offspring. The timing of insemination relative to the ovulation period has been identified as a promising approach for the pre-selection of offspring sex; however, proper detection of oestrus is crucial. Among all the approaches reported, dietary manipulation could be regarded as the most affordable and stands a better chance of being optimised for commercial livestock production. Reduction in the cost of desired sex production by adopting sex pre-selection techniques will lead to the improvement of the economy and minimise the culling of the undesired sex. However, further research is necessary to focus on the understanding of the underlying molecular mechanisms for the production of animals of the desired sex.