Evaluation of he performance Naked neck (Na/Na, Na/na) dwarf (de/de, de) gene lines under low selection intensity

Abstract

Naked neck and dwarf gene lines which were under low intensity of selection for 6 week body weight for 11 generations, were utilized in the present study. The body 'N'eight at 6 weeks in 11 generations since 1995-96 to 2005-06 ranged between 798 and] 217 g in naked neck gene line and 601 and 834 g in dwarf gene line. No definite phenotypic trend in gain in body weight was observed over generations in both the lines. Phenotypic response in 6-week body weight was -15.48±11.12 g in naked neck and -8.97±6.59 g in dwarf gene line, which were nonsignificant. Genetic and phenotypic parameters for growth and production of 11 th generation were analysed. The average body weight at 4week and 6-week, respectively were 467.30±0.67 g and 877.60±0.10 g in naked neck and 258.55±0.66 g and 607.32±0.12 g, respectively, in dwarf gene line (SII generation). Heritability estilnates (h2S) of 4-week and 6-week body weight, respectively, were 0.16 ± 0.08 and 0.06 ± 0.05 in naked neck and 0.16 ± 0.09 and 0.13 ± 0.08 in dwarf. Genetic (rg ) and phenotypic (rp) correlations between these 2 traits were O.56±0.33 and 0.42 in naked neck and 0.45±0.44 and 0.57 in dwad·. The average production performance of ASM~ 20-week body weight, 40-week body weight, 28-week egg weight, 32-week egg weight, 40-week egg weight and 40-week egg production were 175.81±O.09 d, 2349.15±2.15 g,3 157.90±2.23 g, 53.46±O.02 g, 57.58±0.02 g, 61.45±0.03 g and 62.60 eggs ±O.14, respectively, in naked neck and 151.50 d ± 0.05,2 103.98 g ± 2.80,2562.93 g± 0.79,48.94 g ± 0.01, 52.32 g ± 0.01,56.54 g ± 0.01 and 59.30eggs ± 0.08, respectively, in dwarf. In naked neck the heritability estimates from sire component were high for majoIity of the traits, while in dwarf the heritability estimates of the traits fronl sire cOlllponent were low except for egg weights at 28 and 32 weeks of age, which were high. The genetic and phenotypic correlations between different combinations of traits varied in different directions and magnitude in both lines.