The lack of ability to sex birds in ovo is a major welfare and economic concern for the layer industry. Scientists at the Francis Crick Institute and the University of Kent used the gene editing technology CRISPR/Cas9 to create female-only and male-only mice litters. The findings, published in Nature Communications, could provide a genetic solution for the male chick layer dilemma. “We have developed a method for 100% efficient sex selection of offspring sex in mice, and we believe this will be readily adaptable to other species including livestock, should public opinion and legislation allow for the use of this type of genetic technology in the food chain,” Peter Ellis, co-author of the paper. Approximately 6-7 billion male layer chicks are culled each year, a major animal welfare and economic concern for the layer industry. Producers spend more than $70 million in labor and energy to incubate and sex these eggs and the value of wasted eggs in the U.S. is more than $440 million annually.
Animal welfare organizations have pressured the egg industry to find an alternative approach. However, there are currently several barriers to using gene editing in poultry. Birds require a different gene editing approach than the one used in mammals. Process used for avian species makes genetic edits to primordial germ cells, the progenitors for sperm and ovum cells in the chicken. “As a very loose guideline, designing and demonstrating the principle in laboratory mice has taken six years of work up till now, much of it in cell line work. A similar time frame would be required for proof of concept in a farm species, followed by a further scale-up period before it could be deployed widely,” said Ellis. “The mechanics of sex chromosome expression and silencing are different between poultry and mammals, so this is an area where cell line work will be needed prior to any in vivo work.” Nonetheless, this is an exciting finding that could one day have important implications for the poultry industry.