EDMONTON – Large litter sizes may seem like a bonus at birth, but the variety of size from runts to large piglets can cost money later in the finishing barn, says a University of Alberta researcher.
“The larger the litter size, the more chance of runt pigs,” reproductive physiology professor George Foxcroft told a swine breeding management workshop at the Swine Research and Technology Centre on the U of A campus.
“If you’re getting more and more per litter, but each pig is smaller, what is the cost if you have to feed more smaller pigs?”
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It’s not unusual for a sow to have 14 piglets per litter in a variety of sizes, said Eduardo Beltranena, a pork research scientist with Alberta Agriculture. The range of size is what’s becoming a problem, he added.
“You get too much variation and have large pigs and little pigs. You get little pigs because they were too crowded in the uterus.”
Ensuring good development
At the swine research centre, scientists are studying development in the uterus and how it affects pigs later in the grower and finisher barns.
During pig reproduction, a number of eggs inside the follicles are released into the uterus, where they are fertilized by sperm and become embryos. Research has found that there are more ovulations and embryos than the number of pigs that farrow.
The piglet is called an embryo until it develops a shape and then it’s called a fetus.
If too many embryos start to develop, the uterus becomes too crowded and fetal development is restricted. Muscle fibre development is also affected.
Beltranena said by studying how fetuses develop, they may be able to restrict the number of piglets using genetic selection and produce more uniform growth and carcass characteristics in each litter.
