Significant hatch differences were observed in body weights at day old, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 weeks of age. The present observation is in agreement with the reports of
Rao et al., (2004) in Vanaraja and
Reddy et al., (2016) in Rajasri. Significant influence of sex was found on body weight at all ages. Males were found to be significantly (P<0.01) heavier than females at all the ages. This finding is in consistent with the reports of
Daida et al., (2012), Krishna et al., 2012 and
Reddy et al., (2016) in Rajasri breed.
Body weights at juvenile period
The least-squares means for juvenile body weights obtained in the present study were tabulated in Table 1. The overall least-squares means for body weights at day old, 2, 4, 6 and 8 weeks of age were 32.35 ± 0.4, 80.87 ± 0.17, 184.29 ± 0.44, 351.49 ± 0.76 and 576.16 ± 1.10 g, respectively. The results obtained in present study were lower than those reported by
Daida et al., (2012) in Rajasri,
Haunshi et al., (2007), Padhi et al., (2012; 2015b; 2015c) in Vanaraja male line (PD-1). On the contrary, the weights recorded in the present study were higher than those reported by
Dana et al., (2011) in Horro chicken,
Reddy et al., (2016) in Rajasri,
Rajkumar et al., (2017) in Aseel, The differences in body weight reported by different authors may be due to differences in genetic makeup, agro-climatic conditions, feeding, management practices and type of rearing system.
Body weights at grower stage
Least-squares mean body weights in growers are presented in Table 2. The overall least-squares means for body weight at 10, 12, 14, 16, 18 and 20 weeks of age were 741.31 ± 0.97, 878.03 ± 0.91, 1038.9 ± 0.91, 1160.61 ± 0.99, 1271.59 ± 1.27 and 1370.64 ± 1.7 g, respectively. Males were heavier at all the ages, when compared to female birds. The weights recorded in the present study were lower than those reported by
Haunshi et al., (2007) and
Padhi et al., (2015b) in Vanaraja, On the contrary, the weights recorded in present study were higher than those reported by
Krishna et al., (2012), Reddy et al., (2016) and
Srinivas et al., (2018) in Rajasri.
Average daily gain
Average daily gains recorded in the present study were tabulated in Table 3. The analysis revealed significant influence of hatch and sex on average daily gains at all ages studied except the non-significant effect of sex on body weight at 2 and 8 weeks of age. Least-squares means for Average daily gains were 3.47 ± 0.01, 7.38 ± 0.03, 11.93 ± 0.05, 16.06 ± 0.06, 11.85 ± 0.08, 9.79 ± 0.05, 11.51 ± 0.08, 8.83 ± 0.04, 8.34 ± 0.05 and 8.54 ± 0.06 g, during 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18 and 18-20 weeks, respectively. Growth rate of Rajasri birds peaks at 6-8 weeks age and was similar to the reports of
Chatterjee et al., (2002) in Nicobari fowl (backyard) and
Reddy et al., (2016) in Rajasri. The differences in the average daily gains in different breeds may be attributed to different selection criteria, feeding and management practices.
Shank length
Highly significant (P<0.01) hatch and sex hatch and sex differences were observed in shank length at 4 and 6 weeks of age. The overall least-squares mean shank length at 4 and 6 week of age were 47.49 ± 0.05 and 62.18 ± 0.06 mm, respectively. The least-square means of shank length at 4 and 6 weeks of age obtained in the present study was lower than that reported by
Padhi et al., (2015c) in PD-1 Vanaraja male while the least-square means of Shank length at 4 and 6 weeks of age obtained in present study was higher than that reported by
Rajkumar et al., (2017) in Aseel. The varied source birds used in the development of improved varieties might have resulted in the variation in the shank length. Longer and stronger shanks make the birds more fit for forage conditions. The shank length is directly positively correlated with body weights, which is a desirable feature in meat and dual purpose birds.
Heritability
Heritability estimates for body weights were tabulated in Table 4. Heritability estimates through sire component ranged from 0.04 ± 0.016 (BW20) to 0.44 ± 0.05 (BW0). In general, the heritability estimates have decreased in magnitude with age which is in agreement with the findings of
Padhi et al., (2015a) in Vanaraja and
Reddy et al., (2016) in Rajasri. Heritability estimates of body weight at 20 weeks of age (0.04) is close to zero indicates that almost all of the variability is due to environmental factors, with very little influence from genetic differences.
Heritability estimates of shank length at 4 and 6 of age were 0.15 ± 0.03 and 0.13 ± 0.02, respectively. The estimated heritability value of shank length at 6 weeks of age was lower than those reported by
Mallik et al., 2003 in Synthetic broiler chicken,
Rao et al., (2004) in Vanaraja male line,
Niranjan et al., (2008) in PD-1 line,
Haunshi et al., (2012) in Kadaknath and Aseel and
Padhi et al., (2015a) in Vanaraja male line, However, shank length at 6 weeks of age was higher than those reported by
Padhi et al., (2015b) in Vanaraja male line. Shank length is one of the important trait for the success of the rural poultry. Therefore improvement in the shank length which are utilized for the development of improved rural chicken varieties suitable for backyard rearing.
Correlation
Genetic and phenotypic correlations among body weights obtained in present study were tabulated in Table 5. Estimated genetic correlations among body weights are high in magnitude, positive in direction and are significant (P<0.01). Genetic correlations among body weights were ranged from 0.02 ± 0.14 (BW6-BW14) to 0.98 ± 0.01 (BW16 - BW18) respectively. These results were similar to the findings of
Padhi et al., (2015a) in Vanaraja and
Reddy et al., (2016) in Rajasri.
Estimated phenotypic correlations among body weights were low to high in magnitude and positive in direction. Phenotypic correlations obtained among body weights ranged from 0.003±0.01 (BW2-BW20) to 0.93±0.01 (BW 18-BW20), respectively. In present study the phenotypic correlations obtained between body weights were lower than that reported by
Dana et al., (2011) in Horro chicken.
Estimate genetic and phenotypic correlation of body weights with shank length were presented in Table 6. Estimated genetic correlations of body weights with shank length were high in magnitude, positive in direction and are highly significant (P<0.01). Genetic correlations between body weights with shank length were ranged from 0.001 ± 0.14 (BW14-SL4) to 0.94 ± 0.01 (BW4-SL4). Estimated phenotypic correlations between body weights with shank length were low to high in magnitude positive in direction.
Highest and lowest phenotypic correlations were obtained among 0.91±0.01 (BW4-SL4) and 0.02±0.01 (BW18-SL4 and (BW20-SL4), respectively. In the present study genetic correlation obtained between day old body weight and shank length at 4 weeks of age was similar to the findings of
Padhi et al., (2015c) in PD1. Genetic and phenotypic correlations obtained among body weights at 2, 4, 6, 8 weeks of age and shank length at 4 weeks of age were lower than that reported by
Padhi et al., (2015c) in PD1.
Genetic correlation obtained between day old body weight and shank length at 6 weeks of age was higher than those reported by
Rajkumar et al., (2010) in Naked neck broiler chicken and
Padhi et al., (2015c) in PD1. Phenotypic correlations obtained among body weights at day old, 2, 4, 6 and 8 weeks of age with shank length at 6 weeks of age was lower than that reported by
Padhi et al., (2015c) in PD1. The high and positive association with body weights and shank length will help in determining the primary traits of selection for a breeding program. Selection for body weights will also improve the shank length which is important traits with respect to rural poultry.
