Genome-wide association studies of immune, disease and production traits in indigenous chicken ecotypes

Abstract

BackgroundThe majority of chickens in sub-Saharan Africa are indigenous ecotypes, well adapted to the local environment and raised in scavenging production systems. Although they are generally resilient to disease challenge, routine vaccination and biosecurity measures are rarely applied and infectious diseases remain a major cause of mortality and reduced productivity. Management and genetic improvement programmes are hampered by lack of routine data recording. Selective breeding based on genomic technologies may provide the means to enhance sustainability. In this study, we investigated the genetic architecture of antibody response to four major infectious diseases [infectious bursal disease (IBDV), Marek’s disease (MDV), fowl typhoid (SG), fowl cholera (PM)] and resistance to Eimeria and cestode parasitism, along with two production traits [body weight and body condition score (BCS)] in two distinct indigenous Ethiopian chicken ecotypes. We conducted variance component analyses, genome-wide association studies, and pathway and selective sweep analyses.ResultsThe large majority of birds was found to have antibody titres for all pathogens and were infected with both parasites, suggesting almost universal exposure. We derived significant moderate to high heritabilities for IBDV, MDV and PM antibody titres, cestodes infestation, body weight and BCS. We identified single nucleotide polymorphisms (SNPs) with genome-wide significance for each trait. Based on these associations, we identified for each trait, pathways, networks and functional gene clusters that include plausible candidate genes. Selective sweep analyses revealed a locus on chromosome 18 associated with viral antibody titres and resistance to Eimeria parasitism that is within a positive selection signal. We found no significant genetic correlations between production, immune and disease traits, implying that selection for altered antibody response and/or disease resistance will not affect production.ConclusionsWe confirmed the presence of genetic variability and identified SNPs significantly associated with immune, disease and production traits in indigenous village chickens. Results underpin the feasibility of concomitant genetic improvement for enhanced antibody response, resistance to parasitism and productivity within and across indigenous chicken ecotypes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12711-016-0252-7) contains supplementary material, which is available to authorized users.

Understanding farmers’ preference for traits of chickens in rural Ethiopia

“…A recent study by Psifidi et al. () confirmed existence of genetic diversity and supports the feasibility of genetic improvement for enhanced antibody response, resistance to parasitism, and productivity within and across indigenous chicken ecotypes in Ethiopia.…”

“…Diseases resistance attracted the highest mean WTP implying the economic importance of adaptive traits of chickens. In Ethiopia, there exists diverse indigenous chicken gene pool and genetic improvement for enhanced antibody response, resistance to parasitism and productivity within and across chicken ecotypes is achievable (Psifidi et al., ). Therefore, an alternative way to improve village poultry productivity is to target locally adaptable genetic resources that farmers value the most.…”

The effect of commercially available chicken feed and chicken meat on body weight and serum estrogen levels in female albino Wistar rats

“…Augmented cholesterol levels enable body to produce more estrogens and other steroidal hormone as reported earlier (Cerqueira et al, 2016). Therefore, increased cholesterol and fat intake results in more cholesterol formation and storage in the body as adipose tissue ensuing increased growth and steroidal hormone E2 synthesis (Psifidi et al, 2016). E2 plays a vital role in the development of secondary sexual characteristics and also maintains integrity of reproductive cycles in organisms.…”

“…The ingredients of the chicken feed are reported to cause better taste and meat size in chickens and hence providing with proteins and fats to the human body. However, the presence of the certain substances especially roxersone, oyster shells from polluted waters, antibiotics, fats from previous chicken remains and hormones additives in the feed concentrate of the chicken meat may bring harmful effects on the individuals consuming the meat (Psifidi et al, 2016). The consumption of the chicken meat will allow the entry of the components of the feed on which the chickens were grown into the body.…”

“…The chicken normally takes three months time to grow into a broiler, the size fit for its consumption (Marzec et al, 2016). The poultry industry now a day uses feed for the chickens that enable them to grow to a complete size in just one and a half months (Psifidi et al, 2016). The feed given to them are supplemented with many nutritional and nonnutritional products.…”