Some animals are very successful at breeding. Pigs are definitely one of those.
According to the United States Department of Agriculture (USDA), the number of pigs in the USA increased from 66 million in 2011, to around 77 million in 2020.
And no wonder people want more of those animals!
Pigs give meat, skin, and fat for human consumption. They are also playful, friendly, sensitive, and intelligent animals that many consider being smarter than dogs.
However, there is some confusion when it comes to the way pigs reproduce. Some say that piglets hatch, while others claim that pigs give birth. Which one is it then; do pigs lay eggs or do they give birth?
In this post, we’ll address some widespread misconceptions and explain if pigs really laid eggs. Read on!
Table of Contents
Do Pigs Lay Eggs?
No, pigs do not lay eggs. Pigs are placental mammals that give birth to live young. Pigs can produce many offspring, giving birth to 12 to 14 babies per litter. These newborns are called piglets.
There are three types of mammals based on the way they reproduce: monotremes (mammals that lay eggs), marsupials (mammals that give birth to an underdeveloped fetus), and placentals (mammals that give birth to fully developed fetus).
Marsupials include animals like kangaroos, koalas, wombats, wallabies, possums, and others, while monotremes include platypuses and echidnas.
All of these styles of reproduction have some advantages, but also drawbacks.
Advantages And Disadvantages Of Pigs Laying Eggs
The main advantage of a pig hatching would be freedom and mobility; the mother would not be slowed down by having to carry lots of eggs in her belly.
She could more easily escape danger and also hunt for food. If a pig was a reptile rather than a mammal, it could just bury the eggs in the sand or the mud and walk away, without having to worry about abandoning its young.
The biggest disadvantage of laying eggs would be the exposure of the pig’s eggs to predators, weather, and other environmental changes.
Letting the baby develop inside the reproductive tract allows the pig mother to protect it until it’s ready to be born. The baby would be, as a result, more mobile and not as helpless.
Why Don’t Pigs Lay Eggs?
Pigs don’t lay eggs because it is more beneficial to them to give birth to live offspring.
Millions of years ago, every animal laid eggs.
As time passed, some animals slowly evolved and started giving birth to live babies because that was what helped them survive and get their species to the next generation.
The switch didn’t happen at once, it took some time.
Before they stopped laying eggs, mammals had been producing milk for their young. A study on the loss of egg yolk genes in mammals discovered that as animals started producing milk for their babies, the developing offspring became less dependent on the egg as a source of nutrition.
That’s why many animals abandoned the egg completely in favor of the placenta and live birth.
This was what most likely happened with pigs. It was dangerous for pigs and their ancestors to have their shell-covered offspring sitting out in the environment, so they adapted to keeping their babies inside them for as long as possible, around 115 days in most pigs.
How Do Pigs Reproduce And Give Birth?
Pigs reproduce sexually and a male (called a boar) and a female pig (called a gilt or a sow) must be involved. Male pigs become sexually active between months 8 and 10, while females can become pregnant once 8 months old. Birthing in pigs is called parturition or farrowing.
There are several ways of breeding pigs: pen mating, where a boar is let to run with females, hand mating, supervised natural mating, and artificial insemination. Most pig farmers choose to have their sows artificially inseminated which saves them time and allows insemination of up to 50 sows by one boar.
Females get into heat or estrus every 21 days when they are not pregnant. When they are ready to mate, sows will send signals to the boar that they are available. During each oestrus cycle, more than 15-20 eggs are usually ovulated.
Signs that a boar is ready to mate include marking trees with urine and foaming by champing teeth.
To court a sow, a boar will chase her around, nuzzle her head, flanks, and genitals, and push or lean on her.
If the female is receptive, the male will mount her. Copulation lasts a lot longer compared to other species, up to 25 minutes. Boars will produce large amounts of semen (up to 17 oz) to fertilize the sow’s eggs. Most of the fertilizing sperm will reach the egg in about 3-6 h after insemination.
The fertilized eggs will start to grow in the female’s body and after around 112–120 days, a sow will be ready to give birth.
When the farrowing comes (the birth process for a pig), a sow will become restless, stand up and sit down a lot, and often not eat.
Just before the pushing starts, a sow will lay down on her side. The length of labor varies from sow to sow, but in most cases, they will have a piglet every 5-45 minutes. The majority of them will be born head first, with the front legs folded back.
One sow can have two litters of piglets a year and an average litter size of 12 to 14 pigs.
Newborn piglets are still attached to their umbilical cord and it breaks as they struggle and try to walk; the sow will expel the placenta/afterbirth four hours after the last piglet.
Within an hour of birth, a piglet needs to suckle on colostrum, the essential first milk full of antibodies. The strongest ones will suckle from the front teats, which produce more milk.
The piglets should fall asleep at the teats while the sow grunts to them softly.
Depending on the breed of pig, weaning (transition from mother’s milk to solid food) can happen from 4 to 8 weeks of age.
Pigs have an average lifespan of 6 to 10 years but can reach 20 years. They become sexually mature around the 6th and 8th months and their daily weight increases rapidly in this period.
The period from 6 months to about 18 months of age is called adolescence. After the 18th month, they will gain less weight.
What Are Some Animals That Lay Eggs?
According to the University of Georgia, over 99% of the world’s animals reproduce by laying eggs. That’s because most of the animals in the world are insects, and most insects hatch from eggs.
Out of around 6,500 known mammal species, 99% of them give live birth, including pigs. The only exceptions are the platypus and the echidna that lay eggs.
Around 80% of reptiles lay eggs. Out of approximately 11,000 known species of reptiles, most of them lay eggs. The only exceptions are some snakes and lizards that give live birth.
99% of fish lay eggs. Out of around 34,000 known species, less than 400 are livebearers. This includes guppies, mollies, platies, swordtails, and some sharks.
All species of birds lay eggs. This includes all of the 10,000 recognized species of birds. Some ornithologists claim there are twice as many bird species, around 20,000.
Almost all amphibians lay eggs. Out of around 8,000 amphibian species, most will lay eggs in freshwater habitats. There are only a few amphibian species that give live birth (several frog species).
Almost all insects reproduce by laying eggs. Out of around 1 million known species of insects, of which 350,000 are beetles, all lay eggs. The only exceptions are a beetle from Borneo, another from South America, and some aphids.
Scientists speculate that there are between 5 and 10 million species of insects in existence today.
Final Thoughts – Do Pigs Lay Eggs?
In conclusion, pigs do not lay eggs. Pigs are animals that belong to the family of placental mammals called Suidae.
These hoofed mammals develop a placenta that nourishes (via umbilical cord) and protects the fetus while it grows inside the uterus.
The main reason why pigs do not lay eggs is evolution; giving birth to live young helped pigs and their ancestors procreate and survive to this day.
Animals that hatch will have eggs that come in different colors, shapes, and forms!
Some will have blue or white color, speckled patterns, and different textures, while others will be hard, soft, or even gooey. Animals may decide to lay them in the water, underground, or a nest.
Pigs are not one of those animals.
If you were pondering on the question “do pigs lay eggs”, we hope this article removed all doubts.
And if you enjoyed it, here’s a recommendation on another popular read: 20+ examples of birds with white stripes on their wings