Successful placement of gilts into the breeding herd and their ability to remain there through at least three parities has three basic, but very important components, according to James Lowe, DVM, from Carthage Veterinary Service, Carthage, IL.

First, focus on the reproductive traits — particularly early cycling, he says.

Next, treat isolation, acclimation and estrus stimulation as separate and distinct processes and develop a routine for each.

Finally, there are many ways to stimulate estrus, but none are more important than providing good contact with mature, active boars and providing at least 15 sq. ft. of clean, dry floor space.

“Gilts represent the future production of the herd, and optimizing their performance requires proper introduction that includes phenotypic selection, proper isolation, immune management and introduction into the (breeding) herd,” he told those attending a reproduction workshop held during the mid-September Leman Swine Conference in St. Paul, MN.

Lowe focused on farm management strategies to help producers achieve above-average production of the sow herd, including better sow retention through at least three parities.

Replacement gilts are often selected for their body type, feet and leg structure and underline quality, with less emphasis placed on reproductive traits.

“While those phenotypic traits are important, we also know that gilts that come into estrus soon after we begin estrus stimulation have a higher lifetime performance than those that cycle later,” he says. This relationship can only be judged within a genetic line, he cautions, and cannot be used as a benchmark to compare one line to another.

And, he adds, this information is only valuable if it is used to cull late-responders and non-responders, regardless of where the gilts come from or what you paid for them.

Do the Math

Outlining a few assumptions, Lowe says we know that gilts that come into heat within 30 days of boar exposure have more pigs in their first litter and are more likely to stay in the herd.

“Second, we expect about 70% of the gilts to be in heat within 23 days, and 85% within 30 days. If we give PG600 (Intervet, Inc.) to gilts without a recorded estrus at 23 days, post entry, we can get 95% to cycle within 30 days.

“Finally, it costs about $1/day to feed and house a gilt,” he says.

Citing Table 1, Lowe outlines three management options for handling a group of gilts.

All gilts that do not have a recorded estrus within 30 days of entry/boar stimulation (Option 1) or within 70 days of entry/boar stimulation (Option 2)are culled. All gilts that do not have a recorded estrus within 23 days of entry/boar stimulation (Option 3) are given one dose of PG600, and those that do not have a recorded estrus within 30 days post entry/boar stimulation are culled.

“Table 1 shows that of the gilts we breed, we can achieve the highest pigs/sow lifetime by culling the non-cyclers at 30 days post entry — 42.3%, 40.8% and 42.2% for Options 1, 2 and 3, respectively,” he says.

“When we increase the percentage of gilts that come into heat by 30 days post entry with PG600 and still cull at 30 days, we achieve the highest economic returns,” he adds.

Eight Steps to a Better System

Lowe offers a specific set of guidelines for success, regardless of the barn layout or the skills of the people responsible for breeding gilts and sows.

1. Start by approaching gilt management and estrus stimulation in a systematic manner. The entire management team must buy into the program. Assign your best people to breed gilts. “This is hard work and only the best will be successful,” he reminds. “There is as much art as science to successful gilt breeding, so make sure you are on track all of the time.”

2. Separate physical (phenotypic) selection from reproductive selection. Physical selection comes first. Gilts must meet your standards for soundness and underline quality.

   “Gilts are not finishing pigs, but they are not money pits either,” Lowe advises. “Adding $10 to the cost of a gilt adds 30 cents to the cost of each pig she produces over her lifetime. Do not put gilts into the system that will not hold up. They need to go to slaughter at the proper weight and not as breeding herd culls (from the gilt pool),” he stresses.