Cloning horses is difficult, but putting cloned embryos together can help them grow better. Scientists tested this by making horse embryos in groups of 2 or 3. They found that grouped embryos became better quality blastocysts and grew more cells. When these embryos were put into mares, they were more likely to become pregnant early and have healthy foals. This shows that putting horse embryos together can make them develop better and increase the chances of successful pregnancies.