On Thursday I worked with the contract growers for a smaller production flow in the upper Midwest. A big concern of the growers was the upward trend in sale weights and the impact on their facilities and work-load.
Much has been written in the past few months on the very sharp rise in slaughter weights in the US in response to both a decline in feed ingredient prices and a growing shortage of pigs due to PED virus. We have seen this increase in our research facilities also. As producers lay out research priorities for the coming years one item high on their list is heavier sale weights. What are the housing and nutritional requirements if pens aren’t topped for slaughter until 290 lb?
Lots of impacts of going to heavier weights, not the least of which is transportation. A load of 160 market weight pigs now can have a gross weight of over 50,000 lb which may be a problem depending on the tractor and trailer configuration, axles, etc. Truck compartments that normally hold x number of pigs now only hold x-1 due to the increase in size.
I was asked at the meeting if death loss increases as sale weight increases. There is no specific answer to this question other than the days at risk of death may increase if the number of days in the barn for a group increases. I know from personal experience that it is no fun removing a 285 lb dead pig from the pen in the barn furthest from the removal door. I’ve begun showing slides of various ‘dead sleds’ that producers are using to make this task somewhat easier and these always generate comments from the audiences.
What about space for pigs grown to heavier weights? The data is pretty clear on this – the space requirement to maximize individual pig daily gain and feed intake increases with increased liveweight. If the first pigs in a pen are removed for slaughter when the pen average weight is 280 lb, the space requirement for best individual pig daily gain is 9.2 square feet per pig. Yet most facilities are stocked at placement at 7.2-7.5 square feet per pig.
This stocking density won’t change much based on what we currently know about the impact of space on feed conversion (minimal), 10-15 year facility contracts and the regulatory process many producers and production systems face. If pigs are given more space (fewer pigs in a facility), more facilities are necessary for the same number of pigs and facility cost per pig increases. Since feed conversion is not strongly impacted when pigs are given less space the goal of facility management becomes pounds of gain per unit of space, not best individual pig performance. To date there is no strong evidence that space restrictions result in tail biting or other behavioral vices, further leading to keeping facilities fully stocked at the contracted number of pigs.
At the same time, when pigs are given less space feed intake (and daily gain) are capped, meaning less fat is deposited in the carcass of the bigger pigs. I’ve seen entire sets of pigs with 230 lb and greater carcass weights have carcass lean percentages above 55% with backfat depths under 0.8 inches.