Genetics

Achieve accelerated genetic progress in trout farming through access to more sophisticated tools and immense data handling capacity.

GeneticsGenetics and HeredityGenetics is the study of how traits are passed from one generation to the next. Passing of genetic information from parent to offspring is known as heredity, and offspring receive half of their genetic material from each parent through DNA molecules in the sperm and egg. DNA inside the sperm and egg is arranged into chromosomes each containing a set of genes, or small segments of DNA that code for the production of specific proteins inside the cell and organism. The genetic material received from the parents helps determine the physical characteristics exhibited by the offspring.Genetic Diversity and Selective BreedingVariations in DNA sequences inside a specific gene can affect form and function of the protein it produces, ultimately affecting the phenotype. Each individual has a unique DNA sequence resulting in unique physical characteristics. In a large population with abundant genetic diversity, there will generally be many different gene combinations that lead to a wide variety of phenotypes (the set of observable characteristics or traits of an individual resulting from the interaction of its genotype with the environment). Selective breeding takes advantage of the genetic diversity by measuring important characteristics in the breeding population and selecting the best animals to produce the next generation. Practiced over many generations, selective breeding can significantly increase performance in economically important traits and improve the efficiency of animal rearing.Predicting Genetic Improvements:Genetic progress (continual genetic improvement) is achieved by using the following equation called the breeders equation:

Where Δg represents the rate of genetic progress, r = selection accuracy, i = selection intensity, σ = genetic variation and L is the generation interval of the species.
The ability to accurately predict the performance of offspring (r = selection accuracy) has changed over the years as technology advances. The type of data and method used for predictions can significantly influence the speed of genetic progress. Methods of selection include:

Mass Selection – Selection based strictly on measured phenotypes (e.g. body weight). Animals with the most desirable phenotypes are mated to produce the next generation. This process is effective in the short term, but ultimately results in inbred populations if no new genetic material is introduced.

Breeding Value Estimation – Breeding values are a way to estimate the genetic merit of an individual based on its own performance and that of all relatives (aunts, uncles, grandparents, siblings etc.). Calculations are made which allow selection for the best families, and the best individuals within a family. Combined with inbreeding management via pedigreed populations, this method is sustainable long term and can be effective at producing genetic gains for certain traits and is the foundation of many selective breeding programs.

Genomic Selection – The recent advancements and decreasing cost of molecular genetics (analysis of DNA sequences) has made genomic selection feasible. In genomic selection, many thousands of DNA markers are compared between individuals with good and poor performance. Statistical associations are made with each DNA marker and performance, creating a genetic profile associated with good performance. Selection candidates are then genotyped and chosen, based on genetic profile rather than phenotype. Genomic selection offers the most benefit for traits such as disease resistance or yield that cannot be measured directly on the selection candidates.

Gene Editing – This technology allows precise alterations to genes within the genome to achieve improvements in specific traits. This technology offers great potential for improved performance and improved animal welfare; however, it is not widely utilized due to public concerns about genetic engineering. For this reason, Troutlodge/Hendrix Genetics is not currently applying this technology in its breeding programs.

Figure 1: Traditional Selection

Figure 2: Genomic Selection