Through awareness and action on sow mortality, a Minnesota consulting veterinarian and a sow specialist are helping producers take steps to effectively lower sow attrition rates.
All too often, excessive sow mortality is accepted as a fact of life or ignored.
The target for breeding herd mortality for confined sows is below 6%. But many herds face double-digit losses.
The reasons for those losses ripple throughout the production system.
At Bentdale Farms (Dave and Arnie Bentz) at Truman, MN, 1999 to 2002 were especially difficult years. Born alive averaged 10 pigs/litter, while the weaned pig average slipped to only 8.4, explains Fairmont (MN) Veterinary Clinic (FVC) consulting veterinarian Mark Wagner.
Sow mortality was running very high at 15.6% for the 500-sow, farrow-to-finish operation. Figures for sow mortality included all bred females.
Son Dave Bentz recalls that dark time: “A lot of the sows never even made it to Parity 2. We had to cull them right out of the farrowing crate because they just didn't have the right bone structure.
“It messes up your parity distribution,” he continues. “You end up with a lot of old sows that don't perform very well, and you've got a gap in the middle where some of your better-performing sows are supposed to be.”
To complicate matters, Bentz says the herd experienced a number of breaks with the porcine reproductive and respiratory syndrome (PRRS) virus. Abortions from PRRS were few, but sow deaths were high and pigs got sick 10 days to two weeks after weaning.
To deal with this type of chronic infection, Wagner says the key focus must be to provide more uniform herd immunity. To achieve uniform immunity, gestating sows were given a dose of farm-specific live serum and boostered two weeks later with the same PRRS virus serum. (For more details on serum therapy, see “Controversial Procedure Controls PRRS,” National Hog Farmer, June 15, 2004, pages 20-22).
Nursery depopulations were also used to try and stop the PRRS virus and other secondary bacteria from circulating throughout the one-site operation, adds Bentz.
Herd Health Strategies
Wagner's first step to rectify the situation was to establish an overall herd health strategy, starting with a gilt development program. Bentz had used a mixed protocol — producing gilts internally and occasionally buying gilts.
Bentz switched to Danbred genetics in late 2002. This has provided healthier replacement gilts and a sounder breeding female.
PRRS-naïve gilts are purchased at 140-150 days of age, every two months, and brought into an off-site, rented barn for 60 days of isolation and acclimation, explains Wagner.
Gilts are vaccinated for Mycoplasmal pneumonia and swine influenza virus shortly after arrival. Then they are injected with the farm's PRRS virus in a serum therapy program.
Each month, sows that are between 30-60 days of gestation receive a killed PRRS virus vaccine, he adds.
At the gilt barn, gilts are housed in two large pens bedded with straw and with access to the outside. Manure feedback is practiced for acclimation, but no cull animals are introduced.
Farm staff gives vaccinations and treatments, but daily care and management of the gilts are provided by the barn's owner to lessen biosecurity risks, says Bentz.
“It's not a perfect system. But it lessens risk and enhances gilt development, and those are two big keys to improved performance and reduced sow losses,” emphasizes Wagner.
He observes: “I want to stress that a lot of the performance and productivity of the herd really depends on the gilt, and that might be in born live, pigs weaned, sow mortality and longevity.”
Training and educating farm personnel have also played major roles in turning around production, says Wagner. Staff makes sure all gilts/sows get up every day so they can be observed for health and soundness.
Visual appraisals are routinely done for body condition, and periodically sow condition is checked using an ultrasound backfat probe to objectively confirm measurements, he says. Physically handling sows can be vital to check for structural soundness.
Bentz says it's necessary to find out the specific nutritional needs of your breeding stock. He learned that Danbred females need a higher level of lysine, for example. They also have higher feed consumption levels. From weaning to 30 days of gestation, sows are fed 6-8 lb. of feed/day. After 30 days of gestation, sows go on a maintenance diet that averages 5 lb. of feed/day. Near farrowing, sows are brought up to 7-8 lb./day. During the height of lactation, some sows eat 24 lb. of feed — 12 lb. in the morning and 12 lb. in the afternoon.
Efforts Pay Off
Wagner reports staff efforts and herd health strategies are paying off. In 2003 and 2004, pigs born alive has increased to 10.9 pigs/litter, and pigs weaned/litter has climbed to 9.7.
In turn, sow mortality has dropped to 9.7%. Wagner realizes that's still high, but progress has been steady.
Average herd parity is 3.2. That includes a nice mix of younger females and older sows in Parities 5-7 still producing solid numbers. Culling rate averages 41% annually.
Managing Cull Sows
At Bentdale Farms, when cull sows are identified, they are sprayed with the letter “C” on their backs and immediately moved to a separate pen to await shipment.
Age and performance are the two biggest criteria for culling sows. Sows are also culled if they pregnancy check open twice or if they don't return to heat within a week after weaning.
It's important to take action when it appears a sow is a cull candidate, says Sasha Gibson, sow specialist with Preferred Capital Management and a consultant to FVC PigCHAMP bureau. Decide if the sow can be treated. If not, put her on the cull truck, she says.
For culls to retain salvageable value, they still need to be managed as if they are an active part of the breeding herd, she adds. House smaller cull sows away from larger culls to avoid injuries.
Too often culls are ignored and end up being euthanized on the farm, asserts Gibson. Obviously, those animals provide no return to the operation.
She recommends producers use the PigCHAMP report called Removal Analysis to track sows that are culled or have died.
Mortality Study Proves Successful
Preferred Capital Management (PCM) of Fairmont, MN, conducted a study of 14,000 sows on six farms to see if awareness of sow mortality could make a difference in results, reports PCM sow specialist Sasha Gibson.
Sow mortality in June-August 2003 averaged 13.1%, and 11.9% if one farm with high death loss was subtracted. Sow death loss is always higher in summer months.
Farms offered a $500 reward to staff if they could show the most reduction in sow death loss, Gibson explains.
Since all of the farms succeeded in significantly lowering the percentage of sow deaths, all six received the $500 bonus, she says. Average death loss was reduced to around 7% for June-August 2004.
Death loss in those herds has remained historically lower.
“If you can pick an area, use records and be aware, you can make changes,” notes Gibson.
PCM and the Fairmont (MN) Vet Clinic select 2-4 topics each year for hog farm improvement. Every topic has brought improvement to clients' hog farms, she notes.