When pigs start dying, it’s clear that there’s an economic cost to your business, not to mention the impact it has on your staff’s motivation.
Porcine circovirus is common on hog farms, but more recently PCV Type 2 has gained attention and impact. “It has been implicated in several pathologic conditions,” says Tom Gillespie, DVM, Rensselaer, Ind., “including post-weaning multi-systemic wasting syndrome, porcine dermatitis and nephropathy syndrome, pneumonia, reproductive and enteric diseases.” Today these are now broadly termed as porcine circovirus associated diseases.
No question, PCVAD grabs immediate attention when pigs start dying, but there's more to consider than increased mortality and culling rates. There's also reduced growth rates and poor feed efficiency. To gain deeper insight, Gillespie and his colleagues dug into the economic effects of PCVAD on reduced performance and increased mortality in a commercial grow/finish herd.
The review involved a 1,200-sow, farrow-to-finish herd in the eastern Corn Belt. It was diagnosed with PCVAD in December 2004. The system was negative for porcine reproductive and respiratory syndrome. Within that system, pigs were finished in conventional 1,000-head units.
The PCVAD diagnosis was made in 12- to 16-week old pigs, Gillespie says.
The veterinarians collected herd records for six-month periods (December through May) for two years prior to the clinical disease outbreak and adjusted them seasonally for comparison purposes. Of course, records at the beginning and during the PCVAD episode were also considered. The review focused on group performance, including average daily gain, feed efficiency, the number of pigs placed and mortality rates.
“We made the following economic value assumptions,” Gillespie notes.
Average feed cost = $0.132 per kilogram
Mortality opportunity cost = $125 per animal
Average daily gain = dollars per kilogram
“The PCVAD outbreak significantly impacted mortality, average daily gain and feed efficiency,” he adds.
Parameter 2003/2004 2005
Average gain (grams per day)
“The analysis revealed a combined loss of $6.60 per animal during the outbreak phase,” Gillespie says. “The bulk of the cost was from mortality. Culls were not analyzed.”
Note that they analyzed mortality as animals per 1,000 head placed into the finishing units.
Production change: +3.24%
Value in U.S. $: $2.78
Average gain (grams per day)
Production change: -22.7
Value in U.S. $: $2.09
Production change: +0.15
Value in U.S. $: $1.73
PCVAD had been expressed more in the nursery and early-growing pig stages, and occasionally as a reproductive or enteric challenge. But with the disease evolving into the growing and finishing stages, the potential economic impact on a herd and the industry is growing as well.
Gillespie points out that the PCVAD challenge in this herd surfaced clinically as respiratory and systemic disease in finishing pigs. Of course, that will generate attention.
“In this system, individual pigs were not responsive to conventional antimicrobial therapy once clinical expression was underway,” he adds.
Watching for signs of PCVAD is a wise and necessary daily task today. The case definition includes:
Significant increase in cull pigs and in mortality.
Presence of PCV2 virus in lesions found during necropsy.
Symptoms that are non-responsive to treatment.
There is a lot of talk about PCVAD’s harsh impact in PRRS-infected herds, but there is no security to be found in PRRS-negative herds.
“In PRRS-negative herds, PCVAD can play a major economic role in impairing biological and economic performance in growing pigs,” Gillespie says. “Even in herds where the PRRS virus is not present and performance is at or above industry benchmarks, there is need for attentive and effective control strategies.”