15 Reasons for Rising Sow Mortality

Everyone is searching for answers concerning the industry's increase in sow mortality. Changes in pork production, including confinement rearing, evolving genetics, nutrition, a predisposition to disease and animal handling have all been implicated. While pieces from each of those elements fit into the puzzle, the end result is a complicated mix.

Then there's also the people and management factors – both of which play a major role. Certainly sow comfort, handling and welfare influence longevity.

Veterinarians Tim Loula and Paul Yeske, Swine Vet Center in St. Peter, Minn., have pooled their on-farm observations and experiences to come up with 15 potential contributing factors that can play minor to major roles in increasing a herd's sow mortality rate.

"Pork producers should be able to achieve a normal sow attrition rate of less than 5 percent on an annualized basis," contends Yeske. He's seen a tremendous range between herds, with a 10 percent mortality rate plaguing many farms these days.

What's more, Yeske points out the sows that are surviving in today's herds are not necessarily the most productive ones.

As you review the status of your sow herd, here are Loula's and Yeske's checklist of potential causes and contributing factors to mortality rates. It should provide some food for thought and help you develop an action plan for your herd.

1. Labor force
The industry has moved from family workers to an industry where the labor force consists mostly of hired staff. General trends include:

  • Employees lack experience and management knowledge. "They were not raised on livestock farms and have limited natural husbandry skills," points out Yeske.
  • Workers have little or no training. Recent and rapid expansion has left many production units with little time to properly train people.
  • Low unemployment rates of recent years have left many farms understaffed. Increased work loads and prioritization hasn't always allowed for attention to individual animals.
  • Workers aren't owners and there's often a difference in commitment to the herd.

2. Observation skills
Due to limited experience, today's workers may not recognize that an animal is getting sick, going lame, has poor structure or losing weight, until it's too late.

Employees should learn to answer the following questions:

  • Should the animal be moved to a pen?
  • Should treatment begin immediately?
  • Can the animal be culled immediately?

These decisions are based on observation skills that are not only learned but develop from experience.

3. Farm size
In the search for efficiencies involving things like feed delivery, facility size and labor, sow farms have grown dramatically in size. As this occurred, farms have tended to overlook the importance of daily individual sow observation, treatment, culling decisions and housing.

It takes more than 15 minutes to check 1,000 sows, notes Yeske. "It means getting every sow up, putting your hands on the sow and working as a team to get a second opinion."

4. Facility crowding With expensive buildings and narrowing margins, maximizing output to reduce overhead cost on each pig produced is a priority. This has led to excess inventory in barns, which has resulted in fewer available sick pens.

Things like porcine reproductive and respiratory syndrome, artificial insemination, early weaning, and more have necessitated a high sow inventory to satisfy a farm's weekly pig
output goals.

In the past, sick pens were available within the barn, or in outside lots with dirt or bedded floors that could assist in the animal's recovery. But because of increased biosecurity demands, such facilities are no longer considered an option.

5. Culling practices
Traditionally farms would cull sows on an as-needed basis. Animals that looked like they might go lame were proactively culled as soon as possible.

"Today, because of biosecurity, farms have a cull-truck visit once a week, once a month or not until there is a trailer-load of cull animals," says Yeske. "Some sows could be salvaged if they were sold earlier vs. waiting a few extra weeks in the barn."

6. Backfat
The move to genetically leaner and meatier hogs has created animals with much less natural backfat today. When replacement gilts reach maturity with 13 mm to 18 mm of backfat after being on full-feed in the finishing barn, it will be difficult to get them to put on more fat once they start meeting pregnancy and lactation demands.

"I am convinced that thin sows have a higher death rate," says Yeske. However, you don't want an overly fat sow herd because that's not healthy either. "Most often, we're working on the bottom 20 percent to 30 percent of the animals, trying to bring them up to the normal backfat range (16 mm to 19 mm)," he points out.

This is where conditioning scores and ultrasound backfat scanning come in. Both are useful tools, but you have to educate and train workers how to use and interpret them.

7. Phenotypic selection In the past, many farm-based people grew up participating in 4-H, livestock judging and other agricultural classes. Many also received some post-high school instruction in livestock care or judging.

Few of today's workers have this kind of background and, therefore, lack the ability to recognize sound phenotypic traits – especially when animals are in crowded pens.

Owners and workers used to select their own gilts and boars from independent "breeders." Most farms today get replacement animals from a genetic company or their own multiplication system. "Too often, not enough time and effort is committed to selection," says Yeske, "and there's generally less emphasis placed on phenotypic selection."

The animal's body structure and condition, as well as the soundness of its feet and legs influence longevity. Animals exhibiting those problems should be culled before entering the breeding herd, but quotas sometimes prevent that.

8. Artificial insemination
Natural breeding where the boar mounted the sow provided an early indicator that a sow had structural weakness and should be culled. With the increasing prevalence of AI breeding, this early warning no longer happens, and animals aren't culled early enough.

9. Rapid expansion
With the industry's tremendous structural and growth changes since the mid-1990s, demand for replacement gilts has been tremendous. Many genetic suppliers have had to adopt a high selection rate, and at times, standards were reduced to meet the demand. When those animals failed to perform, it caused higher cull or death rates and created a death-spiral effect where the farm required more gilts.

The additional quality gilts weren't available, so selection again had to be adjusted to meet demand. A correction didn't begin to occur until the industry stopped its break-neck expansion rate.

Also, with consumer demand for leaner meat, gilt selection for backfat, muscle, average daily gain and feed efficiency became top priorities. Phenotypic structural traits have been low on the selection criteria list.

10. Parity
"The third and fourth parity is where sows really start to perform," says Yeske. But, with rapid expansion and high sow death loss and culling rates, many herds have experienced parity structures that have shifted to the young side. Coming off gilt development floors with an overly high selection rate, these animals brought with them lower immunity and natural disease resistance, which has lead to poor quality animals reaching sow farms.

Also, in 1998 and 1999 – when live hog prices hit historic lows – many producers (for cash flow reasons) had to stop or reduce replacement gilt purchases. "They tried to keep older sows in production. But if kept too long, older sows will have higher death loss," notes Yeske. So after a move to young herds in 1995 to 1997, the tide turned and by 1998 to 1999 there were more older herds than ever.

"Average parity of farrowed sows on PigChamp records went to six or seven on many farms – a phenomenon I had never seen in all my years of practice," says Loula. Older animals that have been through multiple lactations and breedings traditionally have higher death rates.

11. Feed changes
With the recognition of the relationship between reduced feed particle size and feed efficiency in the grow/finish phase, and with most production systems lacking two different grinds, sows are receiving more fine-ground feed (500 to 700 microns).

Sows are typically fed once a day and because they go on and off feed during lactation, there has been an increase in acute ulcers, resulting in death loss, as well as chronic ulcers that debilitate animals.

This is further complicated in the upper Midwest, where the abundance of low-cost corn keeps sow rations as corn/soybean meal mixtures without other gut-soothing fiber sources.

12. Multiple-site production
Many of today's gilts are raised in multiple-site production situations. Multi-site has been effective in ridding many pigs of common diseases. While this is positive for production, it's not necessarily good for the development of an immune sow. Her first exposure to some organisms (Strep. suis, Actinobacillus suis, Haemo-philus parasuis, Mycoplasma and Pasteurella organisms) occurs when she enters the sow herd. In the past, on farrow-to-finish farms, the gilt had already been exposed to these organisms and was significantly immune.

Isolation in multi-site production has helped ensure that no major organisms are brought into sow herds, but the detriment has been that isolation facilities are difficult to manage. Replacement gilts are often placed in isolation barns where workers do chores at day's end when they're tired and in a hurry to get home.

"So a high level of animal care is often lacking," says Yeske. Also, transportation demands present more opportunities for animals to become injured.

13. Diseases
Diseases that the industry is dealing with today are particularly hard on sow herds. Diseases in the past primarily affected nursery and grow/finish pigs. Swine influenza (H3N2), PRRS (many strains), chronic erysipelas and acute hemorrhagic ileitis are just a few ailments that have become common in sow herds.

14. Changes in product use
Because of the industry's Pork Quality Assurance program, among other factors, producers use fewer animal-health products, especially feed-grade antibiotics. "Fifteen to 20 years ago, we saw these type of products fed routinely during breeding and lactation,"says Yeske. "Today it's rare to see any product being used in either of these rations."

This has been especially true in recent years due to the severe financial crisis and because many producers are PQA-Level III certified and are wary of residues.

"It's difficult to say whether routine use of animal-health products in the feed had a masking effect on diseases such as erysipelas, Actinobacillus suis and others in the past," says Yeske.

15. Physical injuries
"It's hard to quantify, but we are obviously using more sow vaccinations today (psuedorabies, PRRS, SIV, Mycoplasma) in an attempt to make up for a lack of natural immunity." says Yeske.

Every time a sow gets an injection she gets jumpy and some animals become injured. Also, with the large volume of animals being moved from breeding to
gestation, from gestation to farrowing and from farrowing back to breeding, it increases handling risks.

"Each move is an opportunity for injury," says Yeske. Sows can be injured by:

  • Too many animals being moved at once – never more than four at a time, says Yeske.
  • Workers in too much of a hurry.
  • Having alleyways that are too narrow and/or too slippery. Yeske suggests something as simple as using some barn lime.
  • Transporting animals over too long of a distance.

Genetics and intensive confinement rearing are often blamed for the rising sow mortality rate. "This has always been a hard sell for me," says Loula, "because, within systems or with the Swine Vet Center client base, farms with similar genetics and similar facilities can have low sow death loss (2 percent to 5 percent) on an annual basis, or very high rates."

Staff training, gilt availability, selection and acclimatization programs, PRRS control, improving nutrition and feeding skills are all complicated, time consuming tasks, and sometimes without easy solutions.

"The sow herd is the backbone of the entire system, everything falls out from there," says Yeske. Concentrating on making improvements in the previous 15 areas can result in providing better care for the breeding female.