Use of Genomics to Improve Growth28 July 2014
CANADA - Growth is one of the most economically important traits in swine production, and has been for decades. Through traditional genetic selection, along with improved feed and production management, growth rate has significantly improved, writes Nick Boddicker, PhD. for Genesus.
In the early 80’s, nursery to finish growth rate was 0.68 kg per day (Brumm et al., 1982) compared to the present day 0.90kg per day, a 32 per cent increase. However, it has taken over 30 years to make this improvement. Genetic improvement is not a fast process; however, the use of genomics can increase the rate of genetic gain.
Traditional genetic selection has contributed greatly to the improvement of lean gain, and continues to improve gain. The goal of a breeding company is to genetically improve pigs to maximize profitability of the producer. This requires genetic evaluation of pigs, which almost always occurs in a nucleus herd. However, there is a difference between performance in a nucleus environment and performance in a commercial unit. This disconnect is partially due to differences in breed composition, management, and health status. Gathering crossbred performance data to feed into the genetic evaluation can reduce nucleus and commercial performance differences. However, this requires that nucleus level animals are used at the commercial level and unique identification of sires, dams, and pigs in order to tie the information back to the nucleus pedigree.
Genomics has the ability to reduce this disconnect in performance. Genes may be expressed differently in nucleus and commercial facilities, a phenomenon called GxE, or genotype by environment interaction. Therefore, a gene that has a large affect on growth in the nucleus herd may not have as large an effect in a commercial environment, and vice versa. Again, this is due to differences in environments and breed compositions.
Genomic selection can also increase the accuracy of the EBV used for selection at nucleus. In genomic selection, the effect of each genetic marker on a trait is estimated and is subsequently used to predict the performance of other animals. In this case, performance of commercial crossbred animals can be collected and the animals genotyped and used to estimate the effects of each genetic marker. Then, these effects can be used to predict the performance of the selection candidates in the nucleus to determine which sires will produce offspring that perform better under a commercial environment.
Genesus is dedicated to the use of genomics in our system to increase profitability to producers. One area of interest is growth. The company has identified a number of genomic regions associated with growth in our pure lines as well as commercial crossbred animals. Some of these genomic regions have been previously identified; others appear to be novel.
Additionally, predicting purebred performance using crossbred genomic information has yielded reasonably high accuracies. Genesus realises that research and development is critical to genetic improvement; therefore, it invests in technologies that will have long-term benefits to producers. Genomics has an array of uses for all traits, and it says it will continue to invest in genomics, be it the current high-density panels, or sequence information.
Brumm M.C., Peo E.R. Jr., Lowry S.R. and Hogg A. 1982. Effect of source pig, housing system, and receiving diet on performance of purchased feeder pigs. J. Anim. Sci. 55:1264-1271.
To find out more about Genesus Genetics, please take the time to visit their website at www.genesus.com .