A total number of 355 Dokki-4 pullets were chosen randomly at sexual maturity from 3300 chicks produced from 34 sires mated to 87 dams in three consecutive hatches. Traits of egg production were studied in three periods starting from age at sexual maturity (each period was three months) as well as average number of days during which the first ten eggs were laid during each period in order to evaluate the efficiency of different methdos of partial recording. Heritabilities as well as genetic and phenotypic correlations between traits of egg production were estimated. Results obtained are summarized as follows:
1- The averages of age and body weight at sexual maturity were about 173 days and 1525 grams, respectively.
2- The averages of egg number per pullet at the first, second and third periods and total egg number were about 56, 59, 55 and 170 eggs, respectively. The respec-tive numbers of days of the first 10 eggs laid during the same periods were about 16, 14, 16 and 15 days.
3- Differences due to sires and dams in all traits of egg production were significant.
4- The percent of variance due to dam (16.37) was higher than that due to sire (12.27) for age at sexual maturity, indicating that maternal effects are important for this trait. The percentages of variance due to sire for other traits were higher than those due to dam, indicating that sex-linked effects are considered as an important factor in determining egg production. |
