**4.1 Crossbreeding between Nigerian indigenous chicken ecotypes, and genotypes**

The extensive genetic diversity between IC ecotypes as well as within and between population variations in productive traits provide opportunity for improvement of performance through within and between population selective breeding. Ogbu and Omeje [26] reported high within population variation in growth traits in NICs which could be exploited for genetic improvement while [73] recorded improved growth performance following positive assortative mating in NIC populations. Egahi et al. [48] evaluated the effect of crossbreeding between NIC genotypes and reported the body weight of progenies of crosses between normal feathered, frizzle, and naked neck ICs to range from 25.48 ± 0.40 to 28.95 ± 0.45 g for hatch weight, 80.91 ± 0.87 to 91.87 ± 0.78 g, 257.16 ± 3.01 to 283.50 ± 2.41 g, 500.53 ± 7.11 to 639.49 ± 7.94 g, 734.41 ± 7.38 to 842.29 ± 5.88 g, and 1017.63 ± 10.79 to 1121.78 ± 9.94 g, for 4, 8, 12, 16, and 20 weeks of age, respectively (**Table 2**) while [67] observed significant effect of sire, dam, and ecotype on AFE and BWFE of Fulani and Tiv ICs and positive genetic correlations between AFE, BWFE, and EW; and EW, egg length (EL), and egg diameter (ED). Additive genetic heritability (h<sup>2</sup> ) of AFE, BWFE, EW, EL, and ED for Fulani and Tiv ICs were 0.358 and 0.438, 0.420 and 0.398, 0.482 and 0.642, 0.182 and 0.000, and 0.051 and 0.309, respectively. For egg production pattern (clutch size, clutch number, pause number, and pause length), h<sup>2</sup> values were 0.358, 0.412, 0.045, and 0.036, respectively in Fulani chickens and 0.428, 0.391, 0.063, and 0.048, respectively in Tiv chickens [74]. High positive genetic correlations (range: 0.78 to 0.88) were reported between BWFE and AFE, BWFE and EW, EW and EL, and EW and ED. Agu et al. [75] reported significant effect of sire on AFE, weight of first egg (WFE), egg production (EN), egg mass (EM), egg weight (EW), thigh length, back width, and neck length in HE ICs of Southeastern Nigeria. Heritability values for EW, EN, and EM was 0.31 ± 0.30, 0.16 ± 0.13, and 0.28 ± 0.24, respectively and ranged from 0.13 ± 0.23 to 0.52 ± 0.24 from 4 to 20 weeks of age for thigh length, 0.23 ± 0.23 to 0.41 ± 0.29 for back width, and 0.10 ± 0.18 to 0.52 ± 0.44 for neck length. Momoh et al. [46] showed that main (HE x LE) and reciprocal (LE x HE) crossbred progenies were similar in body weight to the HE chickens but superior to the LE chickens. Momoh and Nwosu [76] evaluated the genetic parameters of body weight (BW), body weight gain (BWG), and feed conversion ratio (FCR) in HE, LE, HE x LE, and LE x HE populations and reported h<sup>2</sup> values of 0.17 ± 0.19, 0.08 ± 0.10, and 0.19 ± 0.22 for BW at hatch, respectively. The corresponding values for BW from week 4 to week 20 of age ranged from 0.16 ± 0.18 to 0.43 ± 0.26, 0.16 ± 0.13 to 0.25 ± 0.17, and 0.20 ± 0.21 to 0.36 ± 0.28, respectively. For daily gain from 4 to 20 weeks, 0.03 ± 0.11 to 0.12 ± 0.14, 0.21 ± 0.15 to 0.89 ± 0.50, and 0.10 ± 0.16 to 0.80 ± 0.14, respectively were reported while 0.13 ± 0.16 to 0.41 ± 0.25, 0.10 ± 0.10 to 0.46 ± 0.24, and 0.11 ± 0.16 to 0.24 ± 0.23, respectively were reported for FCR.

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*Utilization and Conservation of Landrace Chickens of Nigeria: Physical and Performance…*

**4.2 Crossbreeding of Nigerian indigenous chicken ecotypes, and genotypes** 

Crossbreeding NICs with exotic breeds/strains is advocated to exploit the high genetic distance and variation between ICs and exotic strains believed to enhance hybrid vigor, heterosis, and breed complementarity. Omeje and Nwosu [58] evaluated progenies of crosses between NIC (LC) and Gold link (GL, an exotic breed) and reported reduced age at first egg (AFE) in LC x GL progenies compared to LC, GL, and GL x LC (155.4 ± 1.49 vs. 157.8 ± 3.21, 169.2 ± 1.65, and 169.7 ± 3.74 d, respectively). Authors also reported superior egg weight for GL, GL x LC, and LC x GL compared to LC (53.44, 47.74, and 47.02 vs. 38.63 g, respectively). The corresponding values for egg mass was 12.12, 10.18, and 8.89 vs. 5.64 kg, respectively. An improvement in annual egg production from 146 eggs/hen for LC to 213 eggs/ hen for GL x LC was reported by [77]. Fewer but longer pauses and shorter but more pauses were observed in LC and LC x GL; and GL and GL x LC, respectively. It was also observed that hybrids of crosses involving LC, Yaffa (Y) and GL exotic chickens [LC(Y x GL), GL (Y x LC), and Y x GL] were superior to LC in egg weight (51.91, 52.07, and 54.22 vs. 40.36 g, respectively), and egg mass (5.40, 5.37, and 6.10 vs. 3.32 kg, respectively) [78] while [79] reported superior body weights for GL, GL x LC, and [GL(GL x LC)] in growth and egg production compared to LC attributed to dominance, epistasis, and/or maternal effects. Oluyemi [80] reported heterosis of 12 week body weight in progenies of LC x White Rock and LC x Rhode Island Red (RIR) to range from 4.0 to 12.4% while significant improvement in BWFE, WFE, ASM, egg production (EN90) and egg weight (EW90) to 90 d was observed in LC x RIR males backcrossed to RIR dams [81]. Ukpong [82] observed improved meat yield in crosses of LC x Abor acre (AA) broiler chickens relative to LC while [49] reported improved growth performance and feed conversion in F2 (main and reciprocal backcross groups) compared to F1 counterparts in crosses of Abor Acre broiler breeder and native chicken genotypes (**Table 2**). Nwachukwu et al. [18] had shown that main crossbred progenies of AA x LC genotypes were inferior in body weight at first egg to their reciprocal crossbred counterparts (960.00, 812.50 and 1030.00 vs. 1891.67, 1576.50 and 2072.00 g, respectively). The latter group also had higher values for WFE, EN90, egg length, yolk index, albumen weight, and Haugh unit and crosses involving the frizzle genotype were superior to crosses involving other IC genotypes. Adeleke et al. [83] crossed complete feathered, frizzle and naked neck ICs to Anak titan (AT) broilers and reported significant effect of sire, dam, and progeny genotype on growth traits. Anak titan sire significantly improved 8 to 20 week body weight compared to IC sires. Significant sire genotype effect on fertility and percent dead in shell was also reported in IC genotypes crossed to AT [84]. Frizzled sire had highest fertility (90.5%) and produced eggs with highest hatchability (91.4%) and least embryo mortality (7.5%) while AT dams produced eggs with highest fertility and hatchability (88.2 and 94.6%, respectively). Main and reciprocal crosses involving the frizzle genotype were also better in the traits studied [84]. Ayorinde et al. [85] observed superior body weight in Fulani ecotype X Dominant black (FE x DB) progenies compared to FE, DB, and DB x FE at 21 weeks of age (1408.50 ± 3.5 vs. 1350.60 ± 4.5, 1388.60 ± 3.2, and 1375.00 ± 3.2 g, respectively). All crossbred genotypes were superior in early (0 to 13 weeks) body weight to FE. Udeh and Omeje [86] reported heterosis of body weight in native and exotic inbred chicken crosses with native X exotic being higher than exotic X native, and native backcrosses being higher than exotic backcrosses. The authors concluded that body weight heterosis resulted from complete dominance in native backcrosses

*DOI: http://dx.doi.org/10.5772/intechopen.96580*

**with exotic breeds**
