As pork producers your primary interests when selecting a genetic source are improvements in efficiency of production and end product quality that result in increased profitability. A complete genetics program, like that offered by National Swine Registry, combining state-of-the-art genetic selection with the genetic diversity of four breeds that can be combined in a mating system achieving 100% heterosis allows you to meet these goals.
The Swine Testing and Genetic Evaluation System (STAGES) is one of the most technically advanced genetic selection programs available. Performance records and pedigree information are combined in a statistical procedure known as Best Linear Unbiased Prediction (BLUP) by an "animal model" that describes gene flow over time and biology of the trait. Pedigree information allows performance records of progeny, cousins, sibs, parents and grandparents to aid prediction of genetic merit. Comparisons can be made across herds where genetic ties are present and when sires have been used in multiple herds through artificial insemination. Daily STAGES evaluations estimate expected progeny differences (EPDs) for each trait and bio-economic indexes are calculated to use in selection of animals for combinations of traits. Special emphasis is given to traits with significant economic impact, including number born alive, litter weight, days to market, backfat depth and pounds of lean. Data are also collected for weaning to service interval, birth weight, loin color, intramuscular fat, and ultimate pH.
How should you identify a genetic source? The first step is to evaluate the suppliers complete genetic improvement program. An evaluation of genetic trends will show the annual genetic improvement that has occurred. Next evaluate herds within the program. STAGES information can be used to compare herds in the same breed by studying rankings in traits of interest for animals used in one herd compared to other herds. The third step is to compare the herd’s average genetic merit to that of the breed. Select a herd that has above average genetic merit for the traits of importance in your operation. Finally, this information is combined with your health requirements and those herds meeting both genetic and health needs should be considered.
When selecting individual animals based on EPDs, select the highest-ranking animals that meet all health and phenotypic requirements. However, this does not imply that only the number 1 sire or animals in the top 10 or 20% in a breed should be used. Any boar in the top 50% is above average and will provide genetic improvement. Remember, the population of animals, the herd that you are selecting in and the genetic improvement program are the most important criteria. Concentrate on identifying superior sires through the across-herd sire summary and then selecting top ranked animals from on-farm programs.
When making any selections remember that EPDs are “estimates” of genetic merit based on varying amounts of information and may change over time as new information is added. The amount of new information will change the accuracy and how well progeny perform will change the EPD. The accuracy value reflects the amount of information that was available to calculate each EPD and should be used as an aid in deciding between two animals with similar EPDs. Regardless of accuracy, the EPD is the best estimate of genetic merit available.
The combination of superior genetics used in a crossbreeding program, and selection of animals based on EPDs enables producers to realize maximum genetic gain and therefore maximum profit. A well-planned mating system utilizes maximum heterosis through the use of purebred animals and appropriate combinations at the parent, grandparent, and great grandparent levels. Crossbreeding is an important part of swine production systems because of improvement in efficiency from heterosis and potential to exploit differences between breeds. A terminal, static cross in which all offspring are market animals takes the greatest advantage of differences in strengths of lines or breeds. Lines that have superior genetic merit for reproduction provide the females and lines that are superior for production traits provide the males. The pigs marketed have high genetic potential for production and the sow herd has high merit for reproductive traits. Ultimately in commercial pork production, selection and crossbreeding are combined to achieve the highest level of performance.
Molecular genetics is also an important part of genetic improvement programs. The most common application is genotyping individual animals for mutations like halothane, napole, and coat color genes. DNA databases have been developed by NSR for use in parentage testing and the identification of QTLs (quantitative trait loci) and SNPs (single nucleotide polymorphisms) that have a major effect on traits of economic importance.
Remember, to maximize genetic potential the genetic source that you rely on must be making constant genetic progress. This is done by combining record keeping systems, testing programs, molecular genetics and genetic evaluation systems based on BLUP statistical methodology into a genetic improvement program. A comprehensive genetic improvement program allows genetic suppliers to make annual genetic improvement. Selections should be made according to genetic potential, compatibility (heterosis), and health requirements.
By selecting a genetic supplier that is performance testing and making genetic improvement in traits that are economically important to your operation and paying close attention to mating programs that maximize heterosis you can be profitable in pork production.