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This experiment was conducted to determine the effects of boric acid (BA) (60 mg/kg of feed) and plant extract mixture (Fitococci, F) (0.75 g/kg of feed), individually or in combination, on egg production, egg quality parameters and blood cholesterol concentration of laying hens in 23 wk of age. After wk 7 of the trial the level of boric acid in feeds were increased to 180 mg/kg. The feeding period lasted 14 wk. One hundred ninety-two pullets (Hyline) were randomly divided into control and 3 treatment groups each containing 48 birds and 6 replicates (each with 8 birds). At the end of the experiment there were no significant effects of dietary boric acid and plant extract mixture inclusion on feed efficiency, egg weights and egg production, egg quality parameters (shell thickness, breaking strength, and shape index) compared with control. But feed intake of hens which were supplemented with plant extract mixture and boric acid were increased (P<0.01). It was also determined that there were no effects of treatments on blood cholesterol levels. As a result, since hens which were fed with basal diet plus plant extract mixture showed better feed conversion ratio at 9-10 wks, this combination of feed additives can be added to diets without any adverse effect on laying hens. But inclusion of 60 mg/kg boric acid is considered better than 180 mg/kg with regard to feed efficiency in laying hens. [ABSTRACT FROM AUTHOR]

In this study, variance components are estimated using different methods for some egg yield traits in a Japanese quail flock that is thought to be bred in terms of egg yield trait. In the study, sexual maturity age (EOY), sexual maturity weight (EOA), egg weight (YA) and egg yield (YV) traits measured on quails are used. Variance-covariance components for these traits are estimated using REML (restricted maximum likelihood), Gibbs Sampling, ML (maximum likelihood) and MIVQUE (minimum variance quadratic unbiased estimation) methods and the estimations of multiple-trait genetic parameters are obtained. The smallest error variance is obtained with Gibbs sampling, which also gave the most unbiased results. BLUP values belonging to each quail are estimated by using the variance-covariance matrices, obtained from the four different methods, in the mixed model equations. Heritabilities were estimated in the range of 0.28-0.38 for EOA, 0.18-0.21 for EOY, 0.36-0.43 for YA and 0.38-0.43 for YV. The highest positive genetic correlation was estimated between EOY and YA traits using all four estimation methods. Spearman rank correlation values between BLUP values obtained using different variance-covariance matrices are obtained in the range of 0.90-0.99 for EOY, 0.96-0.99 for EOA, 0.97-0.99 for YA and 0.96-0.99 for YV. It was thought to be appropriate to use the variance-covariance components, which were obtained via Gibbs sampling approach, in mixed model equaitons in estimation of breeding value. [ABSTRACT FROM AUTHOR]

In this study, variance components are estimated using different methods for some egg yield traits in a Japanese quail flock that is thought to be bred in terms of egg yield trait. In the study, sexual maturity age (EOY), sexual maturity weight (EOA), egg weight (YA) and egg yield (YV) traits measured on quails are used. Variance-covariance components for these traits are estimated using REML (restricted maximum likelihood), Gibbs Sampling, ML (maximum likelihood) and MIVQUE (minimum variance quadratic unbiased estimation) methods and the estimations of multiple-trait genetic parameters are obtained. The smallest error variance is obtained with Gibbs sampling, which also gave the most unbiased results. BLUP values belonging to each quail are estimated by using the variance-covariance matrices, obtained from the four different methods, in the mixed model equations. Heritabilities were estimated in the range of 0.28-0.38 for EOA, 0.18-0.21 for EOY, 0.36-0.43 for YA and 0.38-0.43 for YV. The highest positive genetic correlation was estimated between EOY and YA traits using all four estimation methods. Spearman rank correlation values between BLUP values obtained using different variance-covariance matrices are obtained in the range of 0.90-0.99 for EOY, 0.96-0.99 for EOA, 0.97-0.99 for YA and 0.96-0.99 for YV. It was thought to be appropriate to use the variance-covariance components, which were obtained via Gibbs sampling approach, in mixed model equaitons in estimation of breeding value. [ABSTRACT FROM AUTHOR]