Purchasing ready-to-go gilts places the responsibility for genetic improvement, and management during the rearing period, on the seedstock supplier. However, producers whose operations are in areas with a high risk of disease risk the potential of infecting their entire herd with each incoming load of seedstock-supplied gilts. Because genetics and health directly affect production, producers need to make the decision to raise or to buy replacement gilts based on the specifics of their own operation.
A: Raising your own gilts
Internal multiplication puts producers in full control of the genetic progress and health of their herd. Producers invest in their own nucleus herd of great-grandparent and grandparent stock to produce parent gilts. The grandparent stock is the foundation of the herd and may consist of purebred stock from a seedstock supplier or the top sows in the current herd. Purchasing grandparent stock from a supplier is a costly investment due to their high genetic value. Therefore, it is important to invest in breeding stock that excels in reproductive traits: number born alive and weaned, lactation, longevity, feet and legs, and carcass conformation. Producers who choose to keep back market gilts for the nucleus herd should also choose stock based on reproductive records. These selected sows are then bred to maternal line boars to produce replacement gilts. Selecting the necessary number of grandparent stock for the nucleus herd depends on the needed number of parent gilts -- only 20 percent of the gilts will be kept for breeding.
Initial selection process
The first selection process is at birth. Each piglet should be accurately identified with notches and tags, and have its birth weight, and number of teats recorded. The second screening time comes at weaning when the gilts leave the nursery. Here, producers weigh piglets and record their rate of weight gain. This is also the time to cull problem gilts. Having a good eye for excellent pigs isn't enough when it comes to choosing the top 20 percent for breeding purposes. Record keeping, attention to detail and competence are an absolute.
The final test
A visual analysis is taken of the replacement gilts as they reach approximately 150 lb (68 kg). At this stage, producers should cull gilts with skeletal problems, bad feet and legs, and bad temperament. The remaining gilts are then weighed with their rate of gain recorded. If possible, producers should have the gilts scanned for loineye area and backfat thickness. With such data, producers will then use their best judgment to select the top 20 percent for breeding purposes.
Replacement gilts versus market gilts
Ideally, replacement gilts are sent to development barns at weaning. This gives producers more control over their diet and development. Replacement gilts need to grow, but they also need to conceive, gestate, lactate and breed back quickly. Thus it is imperative when gilts reach 180 lb (82 kg) to start feeding them a nutrient-dense feed that includes nutrients such as biotin, folic acid, choline, plus extra calcium and phosphorous.
In contrast, gilts fed finishing diets are at risk of growing too quickly, which may hinder reproduction and longevity. Another risk of housing replacement gilts with market pigs is the potential to unintentionally mixing them up: sending replacement gilts to market, or, keeping back a market gilt for breeding.
Acclimation and isolation
All breeding gilts should be isolated before they join the base herd. Even replacement gilts that have been raised internally have the potential to carry disease. As a rule of thumb, gilts should be in isolation for approximately 30 days before joining the base herd.
Just as isolation is needed to protect the base herd from potential disease, protecting the health of the gilts is just as important. Here, producers should follow the 30-day isolation period with a 30-day acclimation period.
Acclimation allows gilts to build immunities similar to the base herd. Acclimation is accomplished by adding sentinel pigs into the gilt herd and watching for clinical signs. This helps to establish the level of health between the new gilts and base herd. Proper isolation and acclimation protocol is necessary for all operations and should not be rushed or skipped.
B: Purchasing gilts from seedstock suppliers
Purchasing replacement gilts from a seedstock supplier cuts down management drastically and also eliminates all breeding decisions. Consequently, the genetic merit of the parent stock depends solely on the genetic progress in the seedstock supplier's herd. The benefits of using a seedstock supplier often include year-round availability of sows with performance records for productivity indexes and litter weights, thus guaranteeing a consistent number of quality gilts.
An extra benefit offered by seedstock suppliers is preconditioning -- bringing gilts to breeding age. Producers then receive gilts ready-to-go, with just the isolation and acclimation process to go through.
Another option is to purchase parent stock through a user-group multiplier system. This option consists of several producers investing in a shared-nucleus herd. The goals of this system are to maximize genetic progress and biosecurity while lowering management costs.
Cost and availability
Working with a seedstock supplier means producers need to be in constant communication to guarantee a consistent supply of quality replacement gilts. Producers and suppliers need to negotiate cost and demands at the beginning of their agreement. Seedstock suppliers want to know the expectations and needs of the producer, especially if the producer relies on a supplier for all replacement gilts.
It should be noted that producers need a backup plan in case the number or quality of replacement gilts are not available from either the supplier or user group. A reliable source of quality replacement gilts is essential for production.
Acclimation and isolation
An agreement that allows the necessary time for isolating and acclimating the replacement gilts is an absolute. Some suppliers provide programs that allow gilts to be put into isolation at an earlier age, allowing adequate time to uncover potential disease. Purchasing gilts at a younger age -- under 5 months -- also lowers the temptation to rush them through the isolation and acclimation process. As with the process of raising gilts, we must allow at least 30 days for isolation and another 30 days for acclimation.
Dollar for dollar: cost comparison
The decision to raise or buy replacement gilts ultimately comes down to each individual operation's risks -- health or management. While the risks vary for each operation, the costs come out to be similar. Raising replacement gilts adds approximately 200 more hours of labor a year, plus the extra expense of investing in more costly grandparent stock. Yet, while purchasing replacement gilts may be more affordable -- approximately $80 over the current market price per gilt versus the investment in grandparent stock and approximately $100 per gilt to raise; the trade-off is less cash for less management.
The bottom line is that internal multiplication lowers the risk of bringing disease onto an operation and should be considered by operations in high-risk areas. Operations that have a smaller risk of bringing disease onto their farm -- or that can't afford the investment in management -- would most likely benefit by purchasing gilts from a seedstock supplier.
