**2.2 Genetic and genomic studies at University of Nigeria Nsukka from 2006 to 2020**

The recent studies on chicken with genetic improvement as its main focus are also considered in this section for the purpose of illuminating how the research interest of scientists in these universities and Animal Production Research institute aligns with the global genetic improvement goals and genetic principles. Three cycles of mild selection are for three generations each for growth and egg traits using index selection, which lead to genetic progress in the egg and growth traits of the Nigerian heavy local chicken ecotype that was achieved in the last decade. Estimation of genetic parameter, breeding values, and inbreeding mating system have been employed within the period to achieve improved performance of the Nigerian chicken (Agu et al. [8], Ohagenyi et al. [25], Ohagenyi et al. [26], Ohagenyi et al. [27, 28], Okochi [29], Ezugwu, Emmanuel-Udeozor Ohagenyi et al. [30], Eze [31]).

This last decade has witnessed growing interest and involvement in advanced genetic improvement of the Nigerian chicken. Researcher have embraced genomic studies on local chickens comprising polymorphism of genes (Ghrelin, Ovocalyxin, Ovocledin, Growth factor, and Prolactin) and gene expression (toll-like 5 and NRAMP 1) (Ohagenyi et al. [27, 28, 32], Ikeh [33], Egom [34, 35], Tchoupou [36], Nwapku and [37]). These studies elicited genomic selection as an option for expedite the genetic improvement and creation of new chicken breeds.

The reports of heritability estimates on growth and egg traits of the local chickens and their crosses by Ohagenyi et al. [27, 28], Okochi [29], Ezugwu, Emmanuel-Udeozor Ohagenyi et al. [30], Eze [31], Olatunbosun [38], Olatunbosun [38],

Amusan [39], Akpan [40], Ebangi and Ibe [18], Ndofor et al. [23], Ohagenyi et al. [24] and Momoh and Nwosu [17] ranged from low to high, while genetic correlation were positive and significant in many combination of traits indicating that the local chickens and their crosses could be improved through mass selection.

The study further reveals that all local researches at UNN, Abeokuta, and Shika Zaria laid more emphasis on population performance [8, 17, 18, 23, 24, 38–40]. Many breeding companies lay emphasis on both group and individual.
