Analyzing Sow Attrition

A mortality study involving 30,000 sows from four related systems had a familiar ring – retention rates of parity one and parity two females were too low.

A mortality study involving 30,000 sows from four related systems had a familiar ring — retention rates of parity one and parity two females were too low.

The unacceptable rate of attrition due to involuntary culling was alarming to Jose Piva, technical service director for PIC. Piva's first step in resolving the longevity problem was to identify things the four farms had in common:

  • Pressure to meet a breeding targets;

  • A limited supply of gilts for replacements due to limited multiplication base;

  • Genetic make-up of the sows and health status regarding porcine reproductive and respiratory syndrome (PRRS) and Mycoplasmal pneumonia;

  • Parity distribution (2.9 average);

  • Feed ingredients and management, which included intensive restrictions 4-5 days prior to and 3-4 days after farrowing;

  • Type of crate, feeder, water supply and flooring at farrowing, and

  • Most sows died around farrowing.

Table 1. Reasons for Sow Attrition
Parity 0 Parity 1
Physical/legs/confirmation Ileitis/ulcers Physical/legs Ulcers
Parity 2-6 Parity 7 and up
Physical/legs Vaginal discharge Heart failure/heat stress Physical

Table 2. Target Sow Retention Rate vs. Reality
Parity Target, % Reality, %
P1 100 100
P1-P2 84 72
P2-P3 75 63
P3-P4 66 51
P4-P5 56 42
P5-P6 47 33
P6-P7 35 24

Table 3. Target Gilt Retention Rate vs. Reality
%, (Target/Reality) Target Reality
Born Alive 12.0 pigs 12.0 pigs
Wean 88/88 10.6 10.6
Removal/cull 84/87 10.1 10.4
Nursery/grower 80/81 9.6 9.7
Selection 56/77 6.7a 9.2b
Actually farrow 50/65 6.0 (11% Fallout) 7.8 (15% Fallout)
a(70% Selection rate) b(95% Selection rate)

Pre-treatment Observations

Before deciding on a plan, Piva listed some of the pre-treatment observations collected during the study:

  • Euthanized sows made up over 40% of total deaths;

  • Mortality was higher in summer;

  • Over 60% of the deaths occurred from farrowing to the next potential service;

  • Sows after six parities had a much higher mortality/euthanasia rate than younger sows;

  • Warm water, nipples with high pressure and poor water flow, poor quality flooring, pelleted feed and low particle size seemed to have a negative impact on longevity;

  • Sows with poor legs and low backfat reserve (less than ½ in.) were more likely to die;

  • Building usage pressure, continuous movement of sows and mixing without controlling size of groups predisposed sows to die;

  • High sow mortality had a negative effect on employee morale, and

  • The estimated financial impact of each percentage point of sow mortality was 28¢/slaughter pig.

“Structural soundness was a major cause of culling,” according to Piva, but other reasons for fallout included a lack of daily husbandry. Primary reasons for culling by parity are listed in Table 1.

Addressing the Problems

Once problem areas were identified, Piva implemented the following action plan:

  • Increase gilt replacement pool to remove older parity sows and sows with obvious physical problems or low performance;

  • Improve selection criteria;

  • Implement a favorable gilt developer program that considers age, backfat, number of cycles and weight prior to breeding. Provide more space for gilts;

  • Do not breed sows with more than seven parities;

  • Become more generous with the amount of feed offered to each sow prior to and after farrowing, with the aim to reduce constipation and ulcers. Increase feed particle size to 700-800 microns;

  • Be more proactive in identifying and treating sows correctly. Provide early individual care and immunization;

  • Pay attention to sow comfort, especially farrowing room temperature. Temperature affects cull rate — at 74-76° F., sows won't eat, constipation and ulcers become a problem.

  • Review the current maternal boar inventory for better feet and leg standards. Genetic makeup is a huge variable.

Within a year of applying the changes, mortality levels were reduced, Piva reports. Although they have not reached their target of less than 8% in all of their sow farms, the mortality trend is favorable. Some farms noticed a decrease in mortality levels as early as four to five months after making changes, he says.