The efficiency of a breeding swine herd starts with the gilt (first-parity sow) pool. Sow replacement rates typically range from 53 to 58 percent, and it is a primary goal to have an adequate number of gilts ready for breeding, weighing 300 to 330 pounds (135 to 150 kg), on their second or third estrus. This ensures that gilts have the reproductive maturity necessary for gestation, lactation and rebreeding. Since producers need to identify gilt replacements in advance — around 20 weeks prior to needing the gilt for breeding — planning is required in gilt management.
Gilt pool management success can be improved by focusing efforts on the following five essential tips:
Anticipate Replacement Gilt Needs
To avoid lost profit, increased costs, and problems with pig flow and facility space, ongoing planning is needed for replacement gilt needs. By identifying the number of gilts needed for breeding, you can then avoid the periodic gilt shortages that occur due to seasonal infertility or higher than ideal sow replacement rates. If gilt numbers drop too low, herd managers may opt to breed more opportunity sows and retain sows that should be culled in order to meet production targets.
You can estimate an appropriate gilt pool size for any swine operation by using this simple calculation:
However, this calculation only provides a starting point, as it does not account for factors such as seasonal infertility changes, aging sows, gilt conception rates, herd health status, structural soundness of gilts and sows or production gaps.
Plan Ahead for Acclimation
It’s important to plan ahead, whether gilts are purchased or produced internally, and factor in the appropriate amount of time for isolation, acclimation and a “cooling off” period. Allotting appropriate time needed for these phases is important for minimizing differences in health status between replacement gilts and the sow herd. Introducing gilts into the herd too quickly can destabilize an operation’s high health status by exposing the breeding herd to new pathogens. Heat stress can also contribute to seasonal infertility
Strive for Reproductive Maturity and Effective Estrus Detection
Reproductive performance is optimal when a gilt reaches maturity. A gilt’s maturity is determined by a target age and weight. Gilt estrus stimulation should begin when gilts are 140 to 160 days old and 300 to 330 pounds (135 to 150 kg) to reap several benefits. Gilts with early onset estrus are more sexually mature and are more productive. If a gilt does not show estrus by the time they are 200 days old, herd managers can ship those pigs to market and still capture market hog prices. Once gilts are detected in standing heat with no service, they should be managed so breeding can occur at the second estrus.
A common problem with gilt development is to have a high non-cycling gilt inventory. While exposing gilts to boars through fence-line contact or crates is a common practice, it does not maximize estrus stimulation and may in fact be a contributing factor to high non-cycling gilt inventories. Instead, the most effective method to stimulate gilts is to take the gilts to the boars, especially for heat detection during summer months.
Delay Breeding to Achieve Optimum Weight
While age is more important in determining onset of estrus, body weight is more important at first breeding in determining first-parity sow performance and influencing lifetime performance. Research demonstrates that gilts with breeding weights less than 300 pounds (135 kg) produce fewer total pigs over three parities than gilts weighing more than 300 pounds (135 kg). Delaying breeding from first to second estrus found a 0.7 pig increase in first litter size. In contrast, delaying breeding from second to third estrus only increased litter size by 0.2 pigs for the same extra cost. Breeding should only be delayed to the third estrus to achieve the target breeding weight.
Incorporate Performance Trace Minerals into Swine Nutrition
Proper nutrition is essential to prepare gilts for optimal success in the sow herd. Zinpro recommends that producers feed a diet specifically formulated to meet the needs of replacement gilts. The diet should provide higher levels of calcium and phosphorus to help promote maximum bone ossification or density. Producers should also feed performance trace minerals (zinc, copper and manganese) from Availa® Sow. Research has shown that performance trace minerals help manage inflammation related to sow lameness, claw lesions, milk production and reproduction, while also helping improve claw, joint and bone soundness. Routine claw trimming is recommended when it delivers a positive return on investment to the operation. Claw trimming helps reduce lameness and improves overall sow performance and productivity.
Preparation for first breeding has a significant effect on gilt performance in the sow herd. Advanced planning, gilt-specific nutrition, and fine-tuning estrus stimulation and detection practices are essential. By focusing on the five tips, you can help increase the success of gilt management efforts in your operation.