Gilt development programs are not intended to prevent disease. Instead, the goal is to minimize risk of disease to the sow herd, reminds Grant Allison, DVM. The Walcott, IA, practitioner stresses that producers need to set up a gilt development procedure before purchase or delivery of replacement gilts.
“We are not trying to prevent disease, but trying to minimize risk, so we need to follow the same steps each time,” he says.
Here are Allison's steps:
You or your veterinarian should investigate the health status of gilts being considered.
“The easiest, cheapest way to prevent disease from entering the herd is making phone calls,” he says. “As far as I know, you can't get disease through the phone line.”
Talk to other producers who have purchased gilts from the genetic supplier. Ask if the gilts performed satisfactorily and if they'd buy them again.
Based on that information, analyze the risk. If there are too many red flags, then don't buy the animals, Allison says.
If you're still unsure, ask for specific blood tests and review the results with your veterinarian before the animals are shipped.
If you're buying, ask that the animals be shipped to arrive early in the week. Have your veterinarian take blood samples the same day, so test results can be reviewed the same week.
Before the test results are back, decide what level of disease you are willing to accept, Allison says. That way, when the results arrive, the decision has already been made. If the analysis shows unacceptable health status, you are ready to sell the animals.
“In all cases, producers need to find out health status as soon as possible, to make the best decision they can,” Allison says.
At a 2,500-sow operation, Allison uses tonsil scrapings (taking mucus, tissue, blood and saliva with a long-handled spoon, while the animal's mouth is held open by a specialized snare) from both sows and pigs infected with porcine reproductive and respiratory syndrome (PRRS). This is used to inoculate the incoming replacement gilts with the farm's specific strain of PRRS virus.
First, replacement gilts are tested as feeder pigs to insure they are PRRS negative.
Then, Allison goes into the sow unit and takes tonsil scrapings from sows that show clinical PRRS signs. He targets sows that have had abortions, are off feed or that have litters with a high percentage of stillborn pigs.
Allison continues on to the nursery, where he takes scrapings from sick pigs. In the gilt barn, scrapings are taken from the gilts that were previously inoculated.
All of the scraped material is combined, chilled in isotonic saline solution, and spun in a centrifuge, and the liquid portion is reserved.
Then, the incoming gilts are given a 2 cc. intramusclar injection of the solution. They are tested in two weeks to check their PRRS titer levels, which typically range from 0.6 to 1.2, Allison says.
Allison stresses that gilt vaccinations should include the diseases producers want to avoid, with the exception of PRRS. “I've settled on giving the gilts the PRRS that's on the farm,” he says.
Home-raised replacement gilts are one choice of many available to producers, says Paul Armbrecht, DVM, Lake City, IA.
“Producers need to know they don't have to be pigeonholed into one choice,” he says. “Evaluate each production farm or system, if it's a one-site farm or multiple sites, for whatever is best for the production system, the owners, the economics and the people and their ability to get it done.”
Develop a plan based on the health status of the farm, goals and finances, he says. Then, review the plan with the farm's entire team — nutritionist, genetic supplier, veterinarian and lender.
In-house gilt selection allows for perfect delivery timing and customized phenotypic selection for the system's demands on the breeding female.
“When we select gilts, we select for phenotype more than genotype,” he says. “Genetic improvement may not be as great, but then artificial insemination can bring in new genetics.”