Series: Agriculture
Tags: hogs, pigs, productivity, trade
I recently read a post on farmdocdaily titled “Long-Term Trends in Pigs per Litter.” In it, Michael Langemeier shows that pigs per litter in the United States has increased by 3.15 pigs per litter over 30 years, a growth of about 37.9%. This is huge.
The post reminded me of a graphic I saw years ago. I think it was in one of Jeffrey Perloff’s textbook but I cannot verify because I no longer have the book. If memory serves, the graphic showed the number of pigs per litter in Canada versus the United States. The number of pigs per litter in Canada was higher than in the United States. Lee Schulz explains that this is because of more favourable climatic conditions and greater distances between operations in Canada, which makes it easier to control the spread of diseases. Perloff’s textbook included the graphic to show comparative advantages. Canada (mostly Manitoba) exports piglets to the United States because Canada has a comparative advantage in farrowing, more pigs pet litter, while the United States has a comparative advantage in feeding pigs because of lower corn prices.
I thought I should revisit this and check whether that is still true.
I collected data from Statistics Canada tables 32-10-0201 and 32-10-0336. The older data from table 32-10-0336 are quarterly while the more recent data from table 32-10-0201 are semestrial. I calculated from the data the number of pigs per litter by dividing Pigs born by Sows farrowed. I’m not certain how Sows farrowed is reported. A sow can have a litter twice within a six-month period as sows farrow every five to six months. If a sow that has two litters within a semester is counted as two, then the number of pigs per litter I calculate is correct. If a sow that has two litters within a semester is counted as one, then the number of pigs per litter I calculate is too high.
Figure 1 shows Pigs per litter in Canada between 1999 and 2022. There have been changes to Canada’s livestock survey and the figure suggests the data were not collected the same ways in tables 32-10-0201 and 32-10-0336. I chose to correct the more recent data from table 32-10-0201 by scaling them down to a level corresponding with table 32-10-0336. This is an educated choice based on data overlap between tables 32-10-0201 and 32-10-0336 for a short period (not shown in figure 1) and a sudden increase in the number of pigs per litter calculated from table 32-10-0201.
Based on the corrected data, the number of pigs per litter went from about 10 in 1999 to 12.25 in 2022. The dashed line shows a trend line and the figure includes the equation for that trend line. The value for x is measured in days. The equation tells us that the number of pigs per litter has increased on average by 0.101 pigs per litter per year. If that pace can be maintained, this is a formidable 3.02 pigs per litter over 30 years.
I collected data for the number of pigs per litter in the US from USDA/NASS. There are a few differences in the data I use and those in Michael Langemeier’s blog post; thus the results will differ slightly. I use monthly data and filter the data so they cover the same period as the Canadian data.
Figure 2 shows pigs per litter in the United States. The number of pigs per litter went from about 8.75 in 1999 to about 11 in 2022. Note the big decline in the number of pigs per litter in 2014 from a severe outbreak of Porcine Epidemic Diarrhea (PED). From the trend line, the number of pigs per litter has increased by 0.116 pigs per litter per year, or 3.47 pigs per litter over 30 years.
Figure 3 compares the number of pigs per litter in Canada and in the United States. The difference is large but has shrunk. With growth of 0.101 pigs per litter per year in Canada and 0.111 pigs per litter per year in the United States, it would take almost 100 years for the United States to entirely close the roughly one pig per litter gap.
The data show that Canada farrowing productivity exceeds that of the United States and but the US is catching up, albeit slowly. In the two countries, productivity growth is impressive. Farrowing productivity increased by about 1% per year in Canada and 1.3% in the United States.
Canada still has a comparative advantage in farrowing and continues to export hogs to the United States. In 2022, Canada exported more than 540,000 hogs monthly to the United States. More than 310,000 were piglets weighing less than 7 kg, about 74,000 were pigs weighing between 7 kg and 23 kg, about 30,000 weighing between 23 kg and 50 kg and 120,000 hogs for slaughter. Comparative advantage continues to be a driving force hog trade between Canada and the United States.