Accounting for genotype by environment interaction in economic appraisal of genetic improvement programs in common carp Cyprinus carpio

Abstract

In this study we examine effects of genotype by environment (G×E) interaction due to re-ranking and scaling effects on economic benefit (EB) and benefit to cost ratio (BCR) from a genetic improvement program in common carp at a national level in Vietnam. A discount approach was used for the economic evaluation over a 10 year time horizon. G×E interaction resulting from scaling effects generally had a negligible impact on EB and BCR. However, both EB and BCR decreased with the magnitude of the G×E (i.e. with the decrease in the genetic correlations between homologous traits in the selection and production environments). Furthermore, both EB and BCR from the genetic improvement program depend on other factors, which can be categorized in three groups: i) biological (heritability and feed intake), ii) economic (initial investment, annual recurrent cost, discount rate, price of fish and feed cost) and iii) operational (year when first return is realized, adoption rates of the improved fish by the production sector). The level of heritability affected EB and BCR, with greater heritability being associated with greater EB and BCR. Accounting for feed intake in breeding objectives avoided an overestimation of EB and BCR. Generally, the economic efficiency of the breeding program was almost insensitive to initial investment and annual cost. Increasing the discount rate by three times reduced EB and BCR by a factor of only 1.4 and 2.0, respectively. The price of fish and feed costs had a substantial effect on EB and BCR. However, the greatest contribution to variations in EB and BCR came from increases in adoption rates of the improved fish by the industry. The risk program failure due to technical reasons was extremely low. We conclude that even under the most conservative assumptions, and in the presence of G×E interaction, genetic improvement programs are highly beneficial from an economic viewpoint, and that for the situations studied they could result in EBs ranging from 11 to 226 million US$, and corresponding BCRs of 22 to 420