Meeting the challenge of heavier carcass weights

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The demand from pork processors for heavier carcasses has created a number of challenges for hog producers which need to be addressed in order to ensure that increasing the weight at which pigs are marketed is profitable.

This was the message to producers from Dr. Eduardo Beltranena, with Alberta Agriculture and Rural Development, at the recent Centralia Swine Research Update held in Kirkton, Ontario.

“Packers want heavier carcasses to spread costs over more kilograms of pork processed,” he explains. “However, heavier carcasses mean that hogs stay in the barn longer to reach higher live weights, which implies reduced barn-turnover rates and more kilos of feed per hog sold. Producers question whether there is an economic benefit to them especially at times when pork prices are low.”

Beltranena notes a number of factors which producers must take into account when deciding the best strategy. “The most important consideration producers should make regarding housing hogs in barns longer is pen stocking density up to first pull for slaughter,” he says.

A first step to understanding the implications of higher weights is to calculate the optimum stocking density, using the formula 0.034 x Body Weight 0.67, which will allow the correct number of hogs per pen to be calculated.

“Typical pens measuring 2.5 x 6.0 m (8 x 20 ft.) should house 17 hogs to a market weight of 120 kg,” Dr. Beltranena says. “If filled with 22 hogs, which is a common commercial stocking density, hogs will be crowded for the last third of their stay in such pens.”

He encourages producers to learn how to calculate pen space allocation and the weight at which pigs start to outgrow their space. The potential for crowding finisher pens has also increased due to higher breeding herd productivity, he notes.

Crowding hogs reduces feed intake and consequently weight gain. “Limited floor space and restricted feeder access have additive effects,” Beltranena says. “Research carried out at the Prairie Swine Centre suggests that for every three per cent below the critical individual pen space allocation, there was one per cent reduction in daily weight gain and 0.75 per cent reduction in feed intake.”

Slower growth compounds the pen space problem because pigs take longer to reach market weight.

Returns uncertain

In addition to the challenge of pig flow in the finisher barn, Beltranena says producers may not get a return on the cost of feeding pigs to heavier weights.

“Depending on finishing diet cost and taking into account the poorer feed conversion at heavier live market weight, it could cost $4-$8 more to feed a hog to gain 6.5 kg, giving a five-kg heavier carcass,” he explains. However, he suggests, if crowding hogs results in progressive feed restriction, a reduction in backfat may result in a lower yield class on some packer grids.

“For a common Alberta packer grid, I calculated that a producer would not earn the extra $5 per hog necessary to cover feed costs if average backfat was reduced by two mm due to pigs being kept longer in crowded conditions in order to produce a five-kg heavier carcass,” he says.

Options evaluated

Given that pen space is finite, what are the long-term options to alleviate pressure? A detailed study at the University of Minnesota modelled the implications of selling hogs as they reached market weight, selling hogs within pens to maintain the required space allocation — even if that meant selling them light — selling weaners, reducing sow breedings or constructing additional finishing space.

“They concluded — based on return on equity — that reducing sow breeding was the least preferred, because underutilized sow crates are the most costly asset,” Dr. Beltranena notes. “Selling weaners was the next most undesirable option and selling underweight hogs to maintain within-pen space allocation was intermediate. The best option was to construct additional finishing space as it would be amortized over the long term, followed by marketing hogs as they reached target market weight.”

If producers intend to build some additional finishing space, they should consider constructing in-barn lairage pens because this will allow pigs to be fasted prior to shipping, Beltranena advises.

“Up to $3 worth of undigested feed can be found in the stomach and guts of pigs taken directly from their pen when they have uninterrupted feed access right up to the time of shipping,” he says. “Hogs should be fasted for 12-24 hours, including the time in the plant lairage. Not fasting hogs long enough can affect pork quality, reducing revenue to the producer and the packer.”

The strategy for removing pigs for market also needs to be considered as a means of minimizing the number of days that pigs are crowded. Dr. Beltranena suggests starting the first pull of pigs earlier to create more space for the remaining pigs, even if it means those pigs being slightly light relative to the optimum weight on the packer grid. Another alternative is to market a proportion of the hogs on a lightweight grid or to ship to a small, local abattoir that requires smaller pigs, he says.

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