As feed costs rise, pork producers need to examine areas to improve efficiencies. One area that has increased -- a negative increase -- during the past decade is breeding herd sow mortality. If you can reduce sow mortality, then your pork operation becomes more efficient.
Between 1996 and 2005, breeding herd mortality has risen from 5.9 percent to 8.9 percent. (See accompanying chart.) That’s a 68 percent increase. Even herds with low breeding herd mortality rates have risen at nearly the same rate. In 1995, herds in the top 10 percent averaged only 1.4 percent breeding herd mortality. Today, herds in that group average 4.8 percent. That’s about the same 10-year increase as seen for the industry as a whole.
According to the National Pork Board’s Swine Welfare Assurance Program, breeding herd mortality rates of less than 9 percent warrant no producer action; rates between 9 percent and 15 percent need attention; and rates exceeding 15 percent require immediate attention. Those values and recommendations may change when the new SWAP program is introduced later this year. Many breeding herd consultants recommend a sow mortality rate target of less than 5 percent.
While the industry’s reported averages are still within SWAP’s “acceptable” range, individual herds may have rates that fall into the areas needing attention or requiring immediate attention. Some of the sow mortality increases may be because producers are better at identifying animals that are disadvantaged, ill or injured, as a result of animal wellbeing education.
The accompanying table summarizes scientific findings on sow mortality. It’s clear that there are large differences in rates and reasons. However, a few things stand out. A look at sow mortalities by parity shows that locomotion or leg-related problems tend to occur with sows in their third parity or less. Additionally, arthritis, endometritis, pneumonia, locomotion problems and ulcers appear to be primary causes for death among gilts and young sows. Mortalities due to heart failure, torsion, cystitis and uterine prolapses are common in older sows (beyond the third parity). Moreover, there appears to be a seasonal connection, with summer months showing the highest percentages. Such losses are particularly evident when temperatures exceed 75° F -- typically from late spring through early fall. The added stress appears to affect sows because noticeable increases in heart-related mortalities occur.
Right after farrowing is another time when sow mortality risks are higher. The act of giving birth is stressful. Previous research indicates that nearly two-thirds of sow deaths related to cardiac failure occurred just after farrowing. This same study suggested that other stressful events may trigger cardiac failure. For example, sows that are weaned into a group-housing system frequently fight to re-establish social order. Such fighting is a stressful event that can trigger heart failure. Other events associated with heart problems and mortalities in the breeding herd include mating, transport and elevated temperature.
Sows rarely eat well or consume adequate water during and right after farrowing. This can contribute to some intestinal disorders that can threaten the sow’s life. Some sows develop infections because they fail to expel all piglets or eliminate the entire placenta. That remaining tissue becomes necrotic, and if it’s not recognized and treated quickly it can develop into a life-threatening situation.
As is the case with many other production traits, management and housing appear to contribute to some breeding herd mortalities. Research suggests that abdominal torsions can result from rough handling and movement. Similarly, feeding frequency and/or changes in feed consistency may contribute to gastric torsion or intestinal tract twisting. This could be a problem immediately after farrowing when the sow has been consuming little if any feed, then begins to increase its intake. Studies suggest that increasing feeding frequency may reduce the risk of gastric torsions.
There are other management factors that seem to reduce the mortality risk. These include weaning pigs at 28 days or older, smaller litter size at birth (12 piglets or less), reaching maximum daily feed intake before the 15th day of lactation and holding maximum daily feed intake to less than 17 pounds.
Various recordkeeping organizations report that higher annual breeding herd mortality is associated with larger herd sizes. In a study, the mortality risk increased nearly 0.5 percent when the herd size increased by 500 sows. The increased risk may be associated with a workforce that needs better training.
To reduce mortality within an operation, it’s necessary to determine the animal’s specific cause of death. This means performing necropsies on numerous sows that have died, and it means involving your herd’s veterinarian.
Clearly, the period immediately after farrowing is when sows are at greatest risk. So, barn workers should be particularly attentive to details like farrowing difficulties, checking to ensure that every sow completes the entire farrowing process, monitoring feed and water consumption, and numerous other factors.
With a focused effort, you can reduce sow mortality risks and improve the breeding herd’s efficiency and longevity.