sealPurdue News

October 1996

Hog vaccines protect bottom line and herd health, experts say

WEST LAFAYETTE, Ind. -- Vaccines can improve a hog producer's bottom line, according to research conducted by a team of eight Purdue University animal scientists and veterinarians.

This refutes recent non-peer reviewed research that claimed vaccines reduced hogs' growth.

"There's a misconception out there that by giving pigs a vaccine, you'll slow their growth as much as if they got the disease. That's not the case," says animal scientist Allan Schinckel. "It's a small cost to immunize, both in terms of the money for the vaccinations and in terms of increased time to market weight. The cost is small compared to the cost of disease without use of the vaccine."

Kirk Clark, professor of swine herd health in the School of Veterinary Medicine, says that although most pork producers vaccinate their animals, some have been asking questions about the recent research suggesting that vaccinations aren't necessary.

"There was a group of people out on the lecture circuit claiming that activating the immune system with vaccines slowed growth the same as the animal getting the disease, and since the producer paid for the vaccines, if this were true, it would make more sense to forego the vaccination," Clark says. "We thought all along that this was wrong, and now we have the research to refute it."

According to Schinckel, it is true that the growth in pigs does slow down after vaccinations, but it is a short-term effect. "It's like vaccinating a child," he says. "For a few days after the immunization they might have a slight fever, and they don't feel like eating as much.

"It's the same thing with hogs -- you see reduced growth rates for the first few days, but then they grow even faster. Immunization slows down the time to market by about four days. A diseased animal takes up to 43 days longer to go to attain market weight."

In the study, 140 segregated early-weaned barrows (castrated male hogs) were divided into three groups: 76 barrows received no vaccines, and served as the control group; 32 barrows received moderate levels of vaccine; and 32 barrows received intensive levels of vaccine. The hogs were randomly assigned to pens in the Purdue hog facility. During the study, seven pigs died, six from the control group and one of the intensely vaccinated group.

Pigs were vaccinated against streptococcus , haemophilus , E. coli , bordetella , salmonella , swine influenza virus, mycoplasma and Actinobacillus pleuropneumonea bacteria.

It took the vaccinated pigs three to six days longer than the unvaccinated, quarantined pigs to reach market weight. That's negligible compared to the extra 30 to 40 days needed to bring to market unvaccinated, conventionally weaned pigs that suffer from diseases, Schinckel says.

Clark says, "Diseased animals slow down the growth of lean tissue by 30 to 40 percent while infected."

Clark adds that optimum growth was seen by combining vaccinations with high-health production conditions. High-health conditions refer to a collection of hog management techniques, including segregated early weaning and all-in/all-out, where the hogs are kept together by age and moved through the production cycle in groups. This prevents older sows, which often can be reservoirs of disease, from infecting younger hogs with diseases.

"The average pig produced commercially increases at only 60 to 70 percent of the rate it could achieve in high-health conditions," Clark says. "High-health pigs raised under ideal conditions also attain market weight 40 to 60 days earlier than conventionally weaned pigs."

The research appeared in the journal Swine Health and Production. The research was funded by Genetic Improvement Services and the Indiana Pork Producers Association.

Sources: Allan Schinckel, (765) 463-4756; e-mail,
Kirk Clark, e-mail,
Writer: Steve Tally, (765) 494-9809; e-mail,
Purdue News Service: (765) 494-2096; e-mail,

Effects of antigenic challenge on growth and composition of segregated

early-weaned pigs

Allan P. Schinckel, PhD; L. Kirk Clark, DVM, PhD; Greg Stevenson, DVM, PhD; Kay E. Knox, DVM; Judy Nielsen, DVM; Alan L. Grant, PhD; Deanna L. Hancock, PhD; John Turek, PhD, Purdue University

The purpose of this study was to evaluate the impact of antigen exposure on pig growth from 12 days of age to market weight. One hundred forty barrows were weaned at 10 14 days of age and placed in an off-site nursery. Control barrows (n=76) received no antigenic challenge. Sixty-four barrows, 32 per treatment, received either a moderate or an intense level of antigenic challenge. Antigens, including an Escherichia coli lipopolysaccharide and vaccines, were administered at 12 to 84 days of age, which corresponds to ages of exposure to infectious agents on commercial farms between 12 and 84 days.

Antigen-treated pigs weighed significantly less (P< 0.05) than control pigs on all weigh days between 28 days of age and market; however, after 107 days of age, the antigen-treated pigs grew 11% faster than the control pigs. Antigen-challenged pigs required approximately 4 days more than control pigs to attain 120 kg (264 lb).

Although loin eye area, optical probe muscle depth, and carcass length were initially greater for control barrows, due to compensatory lean growth in the antigen-treated pigs after 107 days of age, the treatment differences in lean mass decreased to 1.4 kg at 120 kg (264 lb).

The antigenic challenges used in this trial explained only a small percentage of the differences in performance between minimal disease segregated early weaned pigs used in this experiment and contemporary, conventionally weaned commercial pigs.

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