Why are Baby Farm Animals Typically Born in the Spring?

This unseasonably warm weather we’ve been having in February has us thinking about spring. And spring on farms usually means babies! Some of my friends even celebrate events like ‘Lambaggedon’. So many baby lambs can be born on a single weekend that family and friends have to come from miles away to help out. They make the event fun with a little contest. Guess the number of lambs to be born between Friday morning and Monday noon. Closest guess gets the privilege of naming one of the lambs.

But why are so many babies born in the spring?

In a lot of ways spring is the perfect time for babies to be born. Mother mammals usually need better, richer food to produce quality milk for their babies to nurse. For grazing animals like cattle, sheep, and horses, the fresh green grass and other plants on pasture in spring and early summer are rich in nutrients. These plants can have a higher percentage of protein and ‘total digestible nutrients’. This can lead to better milk production for the babies. Most calves are born between January and May because of this reason. Read more about early calving here.

Spring is also a good time for babies to be born because the days become longer and temperatures rise. With the warmer weather it is easier for the baby to survive. There is less chance of harsh weather. Just like humans, animals need to be protected from severe weather. Cows often like to wander away from the herd to give birth in solitude. This can put the mother and calf at risk. If the cow has any problems during the birthing process, a farmer might not be available to assist and help pull the calf. Away from the herd, especially in cold weather, the calf might be less likely to survive. Away from the herd, the baby might be in danger from predators like foxes, coyotes, or even large birds of prey like eagles. In many, contemporary farming operations calving and farrowing happens in a barn or ‘under roof’. This protects the mother and baby from many of those dangers.

Because spring is such a good time of year for babies, many animals evolved to accommodate these natural cycles. Many Iowans are familiar with the deer rut that happens in October, November, and December. Male deer are at peak testosterone, get more aggressive, and start fighting for mates. They wander out of their natural habitats which leads to increased motor vehicle accidents when they cross roads. This is in large part because the female deer come into estrus in the fall. As the days shorten, their hormones trigger the estrus cycles. A deer’s gestation will take 201 days. So if the female gets pregnant on October 1, you can expect a fawn around April 20th.

In farming generally, pregnancy and gestation follow these same deep-seated, natural cycles. Cattle gestate for 283 days. So if farmers want to start calving in February, they need to artificially inseminate or introduce the bull into the herd in the middle of April.

However, in contemporary farms piglets and chickens are born year-round. This might be attributed to two main reasons – consumer demand and differences in rates of development. Consumers want fresh meat and eggs year round. They don’t want fresh meat only in the fall when animals born in the spring are fully grown. Because consumers demand fresh meat year-round, farmers try to stagger when their animals go to market. This means that they might have to stagger when the animals give birth. Also, animals like pigs and chickens have much shorter gestation and development rates. Gestation of a pig is roughly 3 months, 3 weeks, and 3 days. Pigs farrow (give birth) and then piglets are usually weaned within a month after being born. This means that a sow could have two or possibly even three litters per year.

Chicken eggs take almost exactly 21 days to hatch. A chicken can lay an egg every single day. This rapid turnaround can produce a lot of birds quickly. Traditionally, chickens did not lay eggs in the winter. With the shorter daylight, their bodies stop producing the hormones that make them ovulate and produce an egg. But on contemporary farms, chickens are raised in barns where the light can be controlled. With artificial lighting, chickens can and will continue to produce eggs year-round. This is a huge convenience for modern shoppers who expect to see eggs in grocery stores even in the winter months.

So, while many farmers are still in tune with the natural cycles of the season with their animals, modern farming practices have helped solve some of the problems that restrict births to only the spring. There is an abundance of babies in the spring, but in agriculture babies might be born all year long.

-Will