Dr. Colleen Lewis / March 29, 2017

Euphemisms are very common in farm life: the early bird gets the worm, don’t count your chickens before they hatch, and why buy the milk if you own the cow? My favorite euphemism is “as useless as teats on a boar.” What??? This is preposterous; teats are very important in the breeding world of pigs. While the euphemism is somewhat true, it does not matter how many teats we find on a boar’s belly. What matters is the number and placement of teats that he will genetically pass down to his daughters.

A gilt is born with a set number of teats; selection for replacement gilts by teat numbers can be as early as five days after birth.  The heritability of teats on a sow comes from her parents. So, this is where the importance of a boar’s teats comes into play. He will typically have between 8 and 14 teats, but his genetic predisposition to have a certain number of teats is highly heritable. If a gilt’s parents carry the genes for 8 teats each, it is likely she will be born with 8 teats and will struggle to feed a larger litter of pigs.  In highly productive herds, the average sow has 10 to 12 baby pigs. The average sow has 10 teats. Selecting for 12 teats in replacement gilts will gradually increase the average number of teats in future gilt litters. Boar teat numbers are equally important; selecting for optimal teat numbers in boars will influence the herd’s genetic progress.

There are several factors related to the ability of baby pigs to survive on a sow: vigor, ability of the sow to produce milk, ………and having a teat to latch on to. The goal of a piglet after birth is to pop up, dry off and find their first meal of warm colostrum. If a sow delivers 15 baby pigs and only has 8 teats, “there’s no room at the Inn!” Another euphemism. There are not enough seats at the dinner table; there are not enough teats for the later born piglets to get their first meal. This is a recipe for disaster. Piglets that may have thrived on a sow with more teats, are fraught with competition and may struggle to survive. Many of the smaller, weaker pigs will perish due to lack of calories and nutrition, or succumb to secondary disease resulting from failure of passive transfer (FPT).

Selecting gilts to enter the reproductive herd that possess 10+ teats and breeding then to boars with 10+ teats will increase the probability of the following:

1. Sows will potentially have daughters with 10+ teats
2. Sows will potentially raise daughters with the genetic makeup of 10+ teats
3. Sows will potentially raise boars with the genetic makeup of 10+ teats

Selecting for teat number is just as important as selecting for litter size. Both are highly heritable and genetic progress can be visualized in just a few generations.

About the Author
Dr. Colleen Lewis is a 1996 graduate of Kansas State University College of Veterinary Medicine. Her career has taken her to many places as a practice owner, consultant, embryologist, and mentor. She enjoys mixed animal practice, teaching, traveling, farming and high school sports with her husband, Andrew and their three boys.