Raising Pigs Efficiently, From Piglet to Market Weight

Raising Pigs Efficiently, From Piglet to Market Weight

To raise pigs efficiently, manage the ratio the whole farm is judged on: total feed purchased divided by total live weight sold. That includes feed eaten by sows, by pigs that died before sale, and by pigs that needed an extra week to finish. Feeding, housing and health all land in the same number, and the largest gains come from decisions that are not about feed at all.

Pen-level feed conversion — feed per kilogram of gain in one group of growers — is the figure most farms track weekly. It is also the figure least able to show where the money went.

Why whole-herd feed conversion is the number that matters

Whole-herd feed conversion is the only feed measure that charges the farm for feed that produced nothing, and the spread between farms is wide. Robert Hoste and Mariël Benus, reporting 2022 InterPIG data for Wageningen Economic Research in 2023, found it ranging from 2.63 in Denmark to 2.87 in Belgium and 3.64 in Italy, with the Brazilian state of Santa Catarina most efficient at 2.38. Feed was 64 percent of Dutch production cost that year.

Spain shows what the number captures. In the same dataset, Spanish sow mortality rose from 9.9 percent in 2018 to 14 percent in 2022 during a severe outbreak of porcine reproductive and respiratory syndrome, and finished pigs per sow per year fell to 23.7 against Denmark's 31.5. Spanish pen-level feed efficiency was ordinary; the herd result was not.

Health spending does not reveal this. Hoste and Benus put veterinary and medicine costs at 2.2 percent of production cost in Denmark and 4.5 percent in Spain, and note that these exclude the cost of animals that underperform. The line item is small. The consequence is not.

How much does weaning age affect pig performance?

Weaning age affects performance more than nursery diet does, and the effect is close to linear. Main and colleagues at Kansas State University, in the Journal of Animal Science in 2004, ran two trials with 5,728 pigs from one 7,300-sow farm.

Pigs weaned at 12 days had 9.39 percent wean-to-finish mortality and returned 94.1 kg of live weight sold per pig weaned. Pigs weaned at 21 days had 3.68 percent mortality and returned 113.1 kg. Pooling both trials, each extra day of weaning age was worth 1.80 kg more weight sold per pig weaned and cut mortality by 0.47 percentage points.

The second finding is the one worth acting on. The same trials tested nursery diets with higher levels of spray-dried plasma and lactose against simpler programmes. Diet complexity had no effect on wean-to-finish growth. Three days on the sow beat a more expensive bag of feed.

Weaning age is usually set by farrowing space rather than by choice, which makes it a buildings decision with a feed-conversion consequence — the kind of link a pen ratio hides.

Raising pigs efficiently starts in the first 24 hours

Colostrum intake in the first day predicts both survival and finishing weight. Quesnel and co-authors, reviewing the evidence in Livestock Science in 2012, report that piglets taking less than 100 g of colostrum in the first 24 hours have preweaning mortality above 60 percent, against 10 percent or less for those taking more than 200 g.

The effect outlasts the nursery. Devillers and colleagues at INRA Saint-Gilles studied 526 piglets from 40 litters for Animal in 2011 and found those consuming under 290 g of colostrum weighed about 15 percent below average after weaning.

Colostrum is available for roughly 24 hours and does not wait. In large litters, split suckling — removing the heaviest piglets for an hour so the smallest can nurse without competition — costs nothing but attention. Drying and warming the lightest piglets first follows the same logic: a cold piglet suckles poorly, and one that misses the first hours will not catch up.

What temperature should finishing pigs be kept at?

There is no single answer, because the comfortable ceiling falls as the pig grows. Renaudeau, Gourdine and St-Pierre's 2011 meta-analysis in the Journal of Animal Science found that the temperature at which feed intake begins to decline drops from 30.3 °C (86 °F) at 10 kg to 21.0 °C (70 °F) at 90 kg. Between 20 and 30 °C, daily feed intake falls by about 32 g per degree at 50 kg body weight and 78 g per degree at 100 kg.

A single setpoint for a mixed barn cannot suit everyone in it. The same analysis found the effect stronger in more recent studies, suggesting that lean, fast-growing modern genotypes are less heat-tolerant than the pigs those setpoints were written for.

What heat costs is subtler than it looks. Vande Pol and colleagues at the University of Illinois ran 316 pigs from 26.9 to 130.9 kg for Translational Animal Science in 2022, comparing a thermoneutral room against a cycle of 30 °C by day and 20 °C at night. Daily gain fell 6.5 percent and feed intake fell 5.5 percent, but gain-to-feed was unchanged.

Heat did not spoil pen feed efficiency. It cost days. Days are invisible in a pen ratio and expensive in a whole-herd one.

A worked example: four degrees in a finishing barn

Take 100 kg (220 lb) pigs in a barn averaging 28 °C (82 °F) rather than 24 °C (75 °F). Using Renaudeau's 78 g per degree at that weight, intake falls about 312 g per pig per day.

At a late-finishing conversion of roughly 3.2 kg of feed per kg of gain, that is close to 98 g of lost gain per day — over a four-week hot period, 2.7 kg (6 lb) less live weight per pig, or 2.7 tonnes across a 1,000-head barn.

Note what the feed bill does: it falls by about 8.7 kg per pig, worth roughly €3.50 at €400 per tonne. Costs went down and the barn still earned less. At 850 g per day of gain, each pig needs three extra days to reach target weight — 3,000 extra pig-days of housing, labour and interest.

Cooling capacity is therefore worth costing against days to market, not against feed saved — as is splitting heavy and light pigs into separate rooms where the building allows it.

Health is a feed cost before it is a veterinary cost

Endemic disease works by converting feed into nothing. Holtkamp and colleagues estimated in the Journal of Swine Health and Production in 2013 that porcine reproductive and respiratory syndrome cost United States producers 664 million dollars a year between 2006 and 2010. Their 2024 update, presented at the International Pig Veterinary Society Congress in Leipzig, put it at 1.2 billion dollars a year for 2016 to 2020, with growing herds accounting for 68 percent of losses against 55 percent a decade earlier.

Farm-level numbers agree. Renken and co-authors assessed 21 endemically infected German sow herds for Porcine Health Management in 2021 and found a median loss of €255 per sow per year, cutting farm profit by 19.1 percent on average and 41 percent in the worst case.

Zhang and colleagues analysed four Chinese farms for Frontiers in Veterinary Science in 2022 and reached ¥1,424.37 per sow across the whole herd. In the fattening units, increased feed cost was the largest single component of that loss, at 44.88 percent. The disease presented as a feed bill.

Two things follow. Biosecurity spending competes with feed spending for the same result, and often wins. And a herd problem with no visible clinical signs can still be the farm's most expensive item, which is an argument for tracking growth rate by group.

Frequently asked questions

What is a good feed conversion ratio for pigs?

For whole-farm feed conversion on a closed-cycle unit, 2022 InterPIG data compiled by Wageningen Economic Research put the best performers near 2.4 to 2.6 kg of feed per kg of live weight sold: Santa Catarina in Brazil at 2.38, Denmark at 2.63. Growing-barn ratios look better because they exclude sow feed and mortality.

Does a more expensive nursery diet improve finishing performance?

Usually not, on its own. Kansas State trials with 3,456 pigs published in 2004 found that raising spray-dried plasma and lactose levels did not change wean-to-finish growth. Diet complexity mattered only for the first days on solid feed. Weaning age moved the result far more.

At what temperature do pigs stop eating?

It depends on body weight. Renaudeau and colleagues, in the Journal of Animal Science in 2011, put the threshold at 30.3 °C (86 °F) for a 10 kg piglet and 21.0 °C (70 °F) for a 90 kg pig. Heavy pigs lose intake at temperatures still comfortable for weaners in the same building.

Every loss above is visible before it becomes a cost figure: a colostrum-starved piglet on day one, a barn four degrees warm in the afternoon, a group gaining 50 g a day below target. Valora Earth's advisor answers that kind of site-specific question in the farmer's own language, using local weather and herd context.