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Background: Being able to model a growth curve using three or four non-linear functional parameters could help explain the growth phenomenon in a precise way and would allow the comparison of an animal's development rate, optimize management and feeding strategies and guide animal production strategies., Objective: The goal of this study was to estimate the genetic parameters of growth traits of Isfahan indigenous chicken in Iran and to determine the best non-linear model describing the growth curve., Methods: The prediction of additive genetic parameters was performed using the REML method by WOMBAT. Direct heritability of the studied traits and genetic correlations between them were obtained. The Logistic, Gompertz, von Bertalanffy, Brody, Negative exponential, Weibull, Janoschek and Bridges models were compared based on the coefficient of determination (R 2 ), mean square error (MSE) and akaike information criterion., Results: The Gompertz model was identified as the best model for describing the growth curve for Isfahan native chicken. The heritability of maturity weights (A), initial weight (B) and maturity rate (K) parameters were 0.223 ± 0.002, 0.016 ± 0.005 and 0.087 ± 0.001, respectively., Conclusion: This study shows that Isfahan indigenous chicken has the genetic potential for improving growth and reproduction based on their desirable heritabilities and correlations using appropriate models., (© 2024 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Background: There have been some reports regarding supplementation of saffron petal extract on performance and egg quality in laying hens. However, the effect of saffron petal extract fed diet at different amounts on antioxidant status of laying hens and the impact of the resulting egg yolk on growth/inhibitory activity of cancer cells has not been fully studied., Objectives: The effect of dried saffron petal extract on the laying performance, egg qualitative traits, antioxidant status, and its inhibitory effect on cancer cells was studied., Methods: A total of 200 39-week-old Hy-line W36 Leghorn laying hens were selected based on a completely randomised design in four treatments with five replications (10 hens per replication). The four treatment diets consisted of a basal diet with no supplement (control), and three diet supplement groups containing 40, 60 and 80 ppm of saffron petal extract., Results: Adding 80 ppm of saffron petal extract to layer diets increased egg production (p < 0.05). Malondialdehyde,1,1-diphenyl-2-picrylhydrazyl value and Superoxide dismutase significantly improved by saffron petal dietary supplementation. The yolk weight and colour, Haugh unit and shell weight and thickness were also influenced (p < 0.05) with highest values achieved in the 60 ppm saffron extract supplemented diet. Results demonstrated a significant effect of saffron extract inclusion in the diet on the growth of Michigan Cancer Foundation-7 and Prostate Cancer Cell in a positive dose-dependent manner (p < 0.05) and the most intense inhibitory effect on cancer cells was observed with 60-80 ppm extract., Conclusions: Saffron petal extract can be used to potentially modulate the antioxidant status of laying hens and the inhibitory effect on cancer cells, best achieved with 60-80 ppm extract., (© 2022 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Objective: During the last decade, genetic evaluation of dairy cows using longitudinal data (test day milk yield or 305- day milk yield) using random regression method has been officially adopted in several countries. The objectives of this study were to estimate covariance functions for genetic and permanent environmental effects and to obtain genetic parameters of 305-day milk yield over seven parities., Methods: Data including 60,279 total 305-day milk yield of 17,309 Iranian Holstein dairy cows in 7 parities calved between 20 to 140 months between 2004 and 2011. Residual variances were modeled by homogeneous and step functions with 7 and 10 classes., Results: The results showed that a third order polynomial for additive genetic and permanent environmental effects plus a step function with 10 classes for the residual variance was the most adequate and parsimonious model to describe the covariance structure of the data. Heritability estimates obtained by this model varied from 0.17 to 0.28. The performance of this model was better than repeatability model. Moreover, 10 classes of residual variance produce the more accurate result than 7 classes or homogeneous residual effect., Conclusion: A quadratic Legendre polynomial for additive genetic and permanent environmental effects with 10 step function residual classes are sufficient to produce a parsimonious model that explained the change in 305-day milk yield over consecutive parities of Iranian Holstein cows.