ABSTRACT

A total of 215 day-old poults were used to evaluate the quantitative genetic effects of the growth traits of the domestic turkey (Meleagric gallapavo) in south-east Nigeria. Heterosis, Reciprocal effect, GCA and SCA were also estimated. A full diallel crossing experiment was conducted using three phenotypes of indigenous domestic turkeys with the following plumage colour: black, white and lavender (spotted). The poults used for the study were hatched from a foundation stock of 86 turkeys comprising 25 Hens and 5 Toms for black and white phenotypes each, respectively and 21 Hens and 5 Toms for lavender phenotype. A mating ratio of I male: 5 females was employed. Firstly, the experiment was designed as a 2x2 factorial in a completely randomized design (CRD), with Batch as block and Phenotype as main factor to check interaction between Batch and Phenotype. Randomized complete block design (RCBD) was also used to analyze the data with phenotypic class as a major factor and batch as block. Data obtained were subjected to analysis of variance (ANOVA). Results obtained showed that body weight (BW) and Linear body traits (body length, wing length, drumstick length, breast width, shank length, keel length and neck length) had a significant increase as age (weeks) increased for the main (direct) crossbred (black x lavender (spotted), BxS) and Lavender Black compared with its purebred (Black x Black, (BxB), White x White (WxW) and lavender x lavender (SxS) counterparts. There were non-significant (P>0.05) differences in initial body weight of the purebred (31.04, 31.35 and 31.53g), main crossbred (34.86, 34.96, 35.06g) and reciprocal crossbreds (35.02, 35.26 and 35.68g), respectively, whereas final body weights for main crossbred (3710.25, 3732.42 and 3738.66g) and reciprocal crossbred (3791.58, 3795.72 and 3797.44g) differed significantly (P<0.05) across the weeks. There were also significant (P<0.05) differences in average daily weight gain (g/day) among the Fi main and reciprocal crossbreds (336.67, 338.08 and 339.55g), (329.61, 338.08 and 339.55g) compared to their purebred (322.33, 323.55 and 323.38g) counterparts. The significant (P<0.05) difference observed in BW and LBM (BL, WL, BRW, DS, SL, KL and NL) values ranged from 2493.1 to 3320g, 37.50 to 40.26cm, 31.43 to 34.29cm, 28.04 to 30.96cm, 18.95 to 20.24cm, 13.05 to 15.05 cm, 13.81 to 14.06 cm and 17.05 to 17.67 cm, respectively for BW and LBMs. Positive heterosis (hybrid vigour) was observed for BW and all LBMs measured in the main (direct) (BxW, BxS, and WxS) and reciprocal crossbreds (WxB, SxB and SxW) studied, ranging from 0.12 to 0.83,11.35% to 33.64%, 0.56 to 2.70, 1.88% to 8.26%, 0.96 to 2.99, 7.5 1% to 30.88%, 0.48 to 1.18, 4.32% to 13.59%, 0.65 to 8.96, 1.10% to 8.96%, 0.43 to 4.05, 1.67% to 39.89%, 1.31 to 2.49, 7.76% to 14.62% and 0.50 to 2.41, 2.93% to 34.16%, respectively for BW, BL, WL, BRW, DS, SL, RL, and NL. GCA was significant for BL, WL, DS and SL and non-significant for BW, BRW, KL and NL with values ranging from - 0.34 to 0.640, respectively. SCA was also significant for BL, BW, BRW, KL and SL but non-significant for WL, DS and NL ranging from 2.981 to 8.324. Reciprocal effect was not significant for BW and all LBMs with the values ranging from -0.015 to 0.661 for BxW, BxS and WxS crossbreds. There were positive and significant correlations in weeks 14 and 16 between the growth traits measured. It is concluded that the significance (P<0.05) differences observed for most LBMs and BW in different ages (weeks) for GCA and SCA indicates that non-additive effects of genes could be exploited through crossbreeding of BxS, BxW and WxS genotypes to bring about genetic improvement for BW and LBMs. Non-significant differences observed in RE suggests that any of the breeds may be used as sire or dam in planned crossbreeding programmes. Thus, positive and significant pheriotypic relationship between linear body parameters and body weight indicates that an improvement in one trait could lead to a concomitant improvement in others, if environmental factors are negligible.