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Smaller Pigs a Weighty Issue for Industry

For both people and pigs, weight can be a touchy subject. But while many of us obsess about our waistline, it’s the impact of pig birth weights on the bottom line that matters most to producers. As researchers apply genomics to improve disease resilience and sustainability in Canadian pork production, the size factor is weighing heavily on their minds.

“The origin of the piglet has long term effects on productivity and health,” said Dr. Michael Dyck, Professor, Animal Science Division Director, Agricultural Life and Environmental Sciences at the University of Alberta.

In the beginning…

“Origin relates back to their litter and their maternal environment, as a litter is associated with a certain sow or gilt. One key element of origin is birth weight and the implications when piglets are at the lower end of the normal range.”

In a recent series of projects by the National Pork Board (NPB) relating to sow longevity, scientists included sow origin as a contributing factor. This prompted researchers on the Genome Alberta-led project to consider litter effect and maternal effect as they relate to productivity and disease resilience.

“The NPB study found that certain sows produce consistently lower or higher birth weight litters, independent of litter size. It seems those sows have a genetic background and physiology that makes them a high or low birth weight phenotype. We wanted to see if, given a large enough population of sows from both extremes, we could find differences in genotypes that would aid our research. We also wondered if coming from a low versus high birth weight sow would affect piglet health and gut development.”

Of the 2400 sows for which Dr. Dyck and his colleagues had birth weight data, 700 were at the high or low end of the range. In genotyping those animals, researchers found differences between the two groups in regions related to uterine activity, growth control genes and gestational metabolism.

“Clearly, there are regions of the genome that help explain differences between those sows, and that seem to be related to functional gene networks. This gives us valuable data to use in following up and determining what makes certain sows different. Is it ovulation rate or uterine capacity? We need to tease out the reproductive variations and see which ones are related to specific genes and gene expression.”

The highs and lows of research

With the piglets, Dr. Dyck’s team examined ones from both high and low birth weight litters. Piglets from the “low” group tended to have more of the diarrhea-causing enterobacteria and less beneficial bacteria that helps break down fiber and aids digestion.

“It’s really a double whammy when you have more of the bad bacteria and less of the good. We’re seeing that low birth weight piglets with a low birth weight mother have altered metabolic capacity and pathways, as well as different immune function. This may aid us in helping piglets develop and improve their health outcomes, as some from the “low weight” category may be more susceptible to certain disease challenges.”

For the larger project and its focus on genomic differences impacting disease resilience, the knowledge that some of the difference may stem from an animal’s litter of origin is another key piece of the puzzle.

“The more we understand about what makes pigs more productive and less susceptible to disease, the better we can select for those traits. This could lower producer costs and reduce antibiotic use, and the latter is a growing priority for industry.”

As a topic at dinner parties, weight may still be off-limits, but if you want to broach it with scientists or pork producers, they’re all ears.

Smaller Pigs a Weighty Issue for Industry

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