Genetic evaluation of net feed efficiency in indigenous chicken in Kenya

Abstract

Indigenous chicken are a valuable asset and form an integral part of many households in Kenya in terms of food security, economic and social roles. Given their value to the agricultural sector, various interventions are being developed and implemented to realize their potential in the sector. Such interventions involve genetic improvement of production traits which directly translate to increased revenues. However, this is likely to be accompanied with increased inputs, especially feed resources, to complement the high performance. Feed costs account for a major portion of production costs. Therefore, considering feed efficiency in genetic improvement provides an avenue to reduce costs. The objective of this study was to assess the genetics of net feed efficiency (NFE) in indigenous chicken by identifying non-genetic and genetic sources of variation, estimating genetic and phenotypic parameters and determining the relationship between feed efficiency and production traits. Residual feed intake (RFI), residual gain (RG), and residual intake and gain (RIG) were used as measures of NFE, estimated from weekly body weight and feed intake records between 11 to 20 weeks of age. Non-genetic sources of variation were determined using a general linear model. Genetic and phenotypic parameters were estimated using random regression sire model while the relationship between efficiency and production traits (growth, feed intake and maintenance requirement) were determined by multivariate sire models. Sex, hatch group and interaction between sex and cluster significantly influenced (P<0.05) variation in growth and efficiency traits. The NFE traits had considerable genetic variation; the variance declined as age progressed in the case of RFI (112.55g to 6.75g) and RG (6.01g to 0.03g) while the estimates increased throughout the experiment in RIG (17.27g to 1950.11g). The heritability estimates ranged from 0.34 to 0.13 for RFI, 0.77 to 0.00 for RG and 0.67 to 0.98 for RIG, following similar trends as their respective genetic variances. The genetic relationship between feed efficiency and production traits varied with age with estimates being significant in some ages while others had no relationship. The moderate to high heritability estimates show that use of RFI at 98 days (0.34), RG at 91 days (0.30) and RIG at 98 days (0.52) and 119 days (0.48) in breeding programmes aimed at improving meat production would be the most effective. Considering correlated responses on production traits, selection for RG between 77 and 91 days of age would be the most suitable. This is because it was associated with higher growth rates (0.55 to 0.42) and equally improve RFI (-0.67 to -0.99) and RIG (0.46 to 0.73). Consequently, improved RG between 77 and 91 days of age will not have significant influence on feed intake (0.04 to 0.14) and maintenance requirement (0.05 to 0.19). The results from this study need to be applied with caution given the high standard errors for the genetic parameters resulting from the small sample size and single generation of birds. In conclusion, there is scope for genetic improvement of feed efficiency alongside production traits in indigenous chicken breeding programmes.