i. Livestock Systems Research: The research group headed by Prof. I. F. Adu undertook livestock systems studies and extension activities in about four villages in Ogun State, Nigeria in1991 and 1992. I personally coordinated the village poultry study sub-group (research completed).
ii. Genetic characterization of the Nigerian local chicken (in collaboration and funded by the University’s Research Grants Committee).
iii. Major genes and their effects on the performance of the local chicken (in collaboration).
iv. Genetic improvement of the Nigerian local chicken for meat and egg production (in collaboration). (Research still in progress).
v. Crossbreeding and selection methods in the productivity of broiler rabbits (in collaboration).
vi. Identification and mapping of the quantitative trait loci affecting growth, muscling, meat yield and fatness in the chicken (research completed and funded by the Commonwealth Scholarship Commission in the UK).
vii. Identification and mapping of the quantitative trait loci controlling trypanotolerance using F6 mouse as a model (research completed).
viii. Effect of frizzling and naked-neck genes on the growth, haematology, organ weights and carcass traits in the Nigerian local chicken (completed – funded by the University’s Research Grants Committee as RG 180).
ix. Molecular screening of MHC resistance genes in West African Dwarf goats (on-going) (IFSERAR Research Grants Scheme, UNAAB).
x. Identification of immune system genes and genetic characterization of Nigerian indigenous sheep and goats (Cornell University, USA – UNAAB Collaborative Small Ruminant Genetics Research Project).
RESEARCH FOCUS AND CONTRIBUTIONS TO KNOWLEDGE:
The focus of my research in the area of animal genetics has been on the genetic characterization and evaluation of Nigeria’s animal resources, with special emphasis on the local chicken, and on the identification and mapping of quantitative trait loci (genes) affecting broiler chicken traits and disease resistance. The population of local chickens in Nigeria, previously put at 120 million (RIM, 1991) and the contributions being made by the breed to food and income needs of the people, especially the rural dwellers, justify this emphasis.
Genetic characterisation and evaluation of Nigeria’s animal resources.
Working with other researchers, I have been able to genetically characterize the local chicken with respect to productivity and the effects of the major genes of frizzling, naked-neck and dwarfism in both the extensive, farmer-managed and on-station, intensive systems. Our publications extend the base of knowledge available on the roles of the major genes, skin and plumage pigmentation genes and plumage distribution in body temperature regulation and productivity indices in a hot, humid environment such as is prevailing in South-Western Nigeria. Studies on pigmentation genes have also been done on another animal species to compare the effects on their performance. These studies have formed the basis for the on-going work at UNAAB on the genetic improvement of the Nigerian local chicken for meat and egg production, preliminary reports of which has been given in our papers.
Our studies have also reported some rare qualitative characters with underlying genetic basis in the local poultry species such as ptilopody, polydactyly, head spurs and comb types and the relationships between these and animal adaptation and productivity. These results highlight the need to conserve these genes for the benefit of the present and future generations of humans.
As part of the work on genetic evaluation, we have estimated some direct genetic and maternal effects and parameters for poultry, pigs, and rabbits. These parameters are important in crossbreeding and selection programmes for animal improvement as some follow-up studies have shown.
Mapping of Quantitative trait loci (QTL) for broiler chicken traits.
Recent trends in livestock genetic research have dwelt on the application of DNA marker technology on animal improvement. Under the conventional methods of animal improvement, the progress made is generally slow and usually involves many generations of breeding and selection. The detection of quantitative trait loci (genes) is a key process in hastening the improvement of animal performance as the major genetic basis influencing the animal species is highlighted much sooner. Using 101 micro satellite markers, we have been able to identify and map the quantitative trait loci (QTL) controlling growth up to 3, 6 and 9 weeks of age, abdominal fat deposition, skin fat deposition, and fat distribution, and meat yield, muscling and muscle distribution in broilers. These publications report the QTLs affecting three of the most important trait groups in broiler birds – growth, fat deposition, and meat yield. The largest single additive effect for growth was on chromosome 4, and the effect of substituting one copy of the gene was an increase in weight of 249 grams. For fat deposition, the largest additive QTL was found on chromosome 7 and accounted for more than 20% of the mean weight of abdominal fat. These results show interesting homology relationships to QTLs in mice and humans. In addition, our comparative mapping studies revealed some candidate genes with likely impact on the traits (conference paper presented by me in Budapest, Hungary in 2001), reinforcing homologous results on obesity in mice and humans. These candidate genes highlight the probable role that the chicken can play in helping to understand the genetic basis for obesity and other fat-related health conditions in humans and how to combat them. In a world that is increasingly conscious of the quality of its food and meat intake, these results are important as they indicate the pathway to a fast, efficient and reliable improvement in chicken meat quality. In which case, direct attention can be focused on the implicated chromosomal regions through the application of the techniques of marker-assisted selection and/or marker-assisted introgression.
Mapping of Quantitative trait loci (QTL) for disease resistance
We have extended the basic principles in QTL mapping to detect genes for trypanotolerance in African animals using mice as model. Our studies using 66 microsatellite markers identified three previously-undetected QTLs for trypanotolerance, one on murine chromosome 17 and two others on chromosome 1 and confirmed (with greater precision, that is, much lower confidence intervals) the previously-detected QTLs on chromosomes 1, 5 and 17. For the first time also, effects of both the old and new QTLs on the early and late phases of survival following exposure to Trypanosoma congolense were highlighted by our study and they show that while the chromosomes 5 and 17 QTLs are important in both phases, chromosome 1 QTLs manifest their effects mainly in the early phase of survival. Using comparative mapping techniques, these results can be extended to larger animals like cattle for which trypanosomiasis has been a major debilitating disease in many parts of Africa.
