Why did Golding have the boys hunt a sow within a litter of piglets? The book is the lord of the flies

Chapter 8, Jack and his hunters graphically murder a sow that is nursing her babies by stabbing a spear up its backside and slitting its throat. This scene is significant throughout the novel because it symbolizes the boys' frustration with living "motherless" on the island. The boys have been living without their parents on the uninhabited island and have gradually descended into savagery. Without their natural parental influence to guide them, they choose to act upon their primitive instincts.