An ISU animal science research team recently made waves in their field by discovering a link between placenta size and litter size in pigs.The team, led by Stephen Ford, professor of animal science, has been working toward developing an understanding of the specific genes required to control litter size. Ford said supervascularization, or a greater number of blood vessels in the placenta, is one of the keys to the experiment.”The placental tissue elongates and dictates how much space is available [for the embryo],” he said.Ford said he is trying to develop a genetic-blood test to determine what size of vascular placenta a gilt grew on.Supervascularization has already been applied to past tests, Ford said. He said he developed a method consisting of sitting behind a sow while it gives birth, tying off each piglet’s umbilical cord with two tags, and snipping the cord so one tag is attached to the placenta and one to the piglet. This allows the team to match each pig with its own placenta, comparing the size and vascularization of the placenta, he said.After letting these gilts and boars grow up, Ford’s team concluded that a large litter will yield smaller pigs with small vascular placentas, and a smaller litter will yield larger pigs with large vascular placentas. Pig litters that had small vascular placentas produced 13 to 14 pigs per litter, while litters whose pigs had larger placentas produced seven to eight pigs per litter. Litters whose pigs had midsize placentas produced the national average, nine to 10 pigs per litter, Ford said.Both Ford and Matt Wilson, a former member of Ford’s graduate student team, said these findings could mean great things for farmers. Wilson worked five years on the project and is now a post doctorate fellow at the University of West Virginia. Basically, raising pigs born with smaller placentas means more pigs for the same amount of money, he said.”Depending on how universal this study is among pigs, if it holds true, it could mean tremendous benefits for farmers,” Wilson said.A $150,000 grant from the U.S. Department of Agriculture and the National Institute of Health funded the research comparing Chinese Meishan and American Yorkshire pigs, Ford said.The Meishan pigs, brought to Iowa State from mainland China, were chosen for the study because of their high litter production. Ford said the pig’s elongation rate, which helps dictate how much space is available for an embryo, is half that of an American pig. Meishan pigs typically produce 13 to 14 pigs per litter, while the Yorkshire typically produces nine to 10 pigs per litter, he said.The pigs were selected for phenotype using microchip technology, Ford said. This technology allows all genes expressed in an animal to be viewed. Ford said he will be attending the Midwest Section of Meetings of Societies of Animal Science in Des Moines to discuss his findings in March.”The novel thing [about the study] is that people have been looking at components of reproduction, but have been ignoring the size and role of the placenta,” Wilson said. “Groups are now interested in how important placental function is and what role it might play with the embryo.”