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The aim of this study was to compare the growth pattern of seven strains of Japanese quail including Wild, Italian Speckled, Tuxedo, Scarlett, English white, White button, and A&M Texas by nonlinear growth functions including Gompertz, Richards, logistic, Lopez, and Weibull functions. The body weights of the unselected randomly bred populations of these strains were measured weekly from 1 to 42 days of age and then used to fit functions. The fitness of each function was assessed by statistics including the mean square error, Akaike information criterion, Bayesian information criterion, and adjusted coefficient of determination. The results showed that Gompertz was the best function for describing the growth curve in Italian Speckled and Wild strains; however, the best function for the other strains was the logistic function. The maximum and minimum values for age and weight at the inflection point were obtained for the White button and Scarlett strains, respectively. The weight to age ratio at the inflection point was maximized for Italian Speckled. The best growth rate was observed for the Italian Speckled strain, whereas the White button strain exhibited the worst growth rate. In conclusion, the Italian Speckled strain had the best properties among the tested strains for breeding as broiler poultry. Research ArticleThis work is licensed under a Creative Commons Attribution 4.0 International License. 442FARAJI-AROUGH et al. / Turk J Vet Anim Sci specific fixed marker genes for plumage color, eggshell color, and brooding groups making similar colonies. It is supposed that these marker genes do not affect the growth pattern in poultry (12), whereas the effect of the roux plumage color mutation on growth was reported by Minvielle et al. (16). The results of several studies showed that selection of the growth function must be strainspecific (12,20). The present study was undertaken to compare growth patterns of quail strains using nonlinear functions. Materials and methodsThe experiment was performed in the Research Center of Special Domestic Animals (RCSDA), Research Institute at University of Zabol, Zabol, Iran. A total of 470 one-day-old Japanese quails including Wild (n = 83), Italian Speckled (n = 136), Scarlett (n = 41), Tuxedo (n = 44), White button (n = 31), English white (n = 64), and A&M Texas (n = 71) strains were obtained from the genetic stock of the RCSDA hatchery from unselected and randomly mating parents. On hatching day, all chicks were identified by wing bands, and they were fed a normal diet containing 250 g CP/kg and 2900 kcal J ME/kg. The birds had ad libitum access to feed and water throughout the experiment. A lighting schedule of 23:1 h (light:dark) was used during the experiment. Room temperature was scheduled to drop gradually from 35 °C the first week to 20-25 °C for the following weeks. Body weights of the birds were recorded weekly. The records for quails that died before 42 days of age were excluded from the analyses.Five nonlinear functions including the Gompertz, Richards, logistic, ...

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A major part of the growth performance in birds is the result of the combined effects of genes, including the general and specific combining ability that requires the design of an optimal mating system. The aim of this study was to fit the best model for each body weight trait from hatch to 45 days and the estimation of the variance components and the genetic parameters for the body weight traits of a crossbred population. This crossbred population was created by 4 strains of Japanese quail, including the Italian Speckled (A), Tuxedo (B), Pharaoh (C), A&M Texas (D), and the body weights of the different combinations were analyzed by 24 models including the direct genetic effect, the non-additive genetic effects including dominance and epistatic effects, the maternal permanent environmental and maternal genetic effects. The selection of the best fit model of each trait was performed based on the deviance information criteria. The variance components were estimated using a single-trait animal model analyzed with Gibbs sampling. At the early stage of bird growth, maternal genetic and maternal permanent environmental effects had a considerable contribution to the best model, but the contribution of these effects reduced with an increase in the bird's age and the additive variance contribution increased. Adding non-additive genetic effects (dominance and epistasis) to the models significantly reduced the variance of the error and the additive genetic variance estimated with high accuracy. The estimated heritability of body weight traits for the body weights of hatch, 5, 10, 15, 20, 25, 30, 35, 40, and 45 d were 0.316, 0.170, 0.251, 0.153, 0.132, 0.164, 0.290, 0.425, 0.476, and 0.362, respectively. The ratio of maternal genetic and maternal permanent environmental was considerable especially on early age body weight but the ratio of dominance and epistatic variances on each of the body weight traits was less than 4.5% of the total variance, but led to a more accurate estimates of the direct additive genetic.

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Carcass yield of meat-type quails is strongly correlated with the weight of the birds at slaughter (slaughter weight [ SW ]; body weight at 45 D of age). Moreover, prediction of superior animals for SW at the earlier stages of the rearing period is favorable for producers. Therefore, the aim of the present study was to predict and optimize SW of Japanese quails based on their early growth performances, sex, and egg weight as predictors through artificial neural network ( ANN ) modeling. To construct the ANN model a feed-forward multilayer perceptron neural network structure was used. Moreover, sensitivity analysis was used to arrange the predictors in the ANN model(s) according to their predictive importance too. In addition, the optimization process was conducted to determine the optimum values for the input variables to yield maximum SW. The best-fitted network on input data to predict SW in Japanese quails was determined with 7 neurons in the input layer, 11 neurons in the hidden layer, and one neuron in the output layer. The coefficient of determination (R 2 ) was 0.9404, 0.9359, and 0.9223 for training, validation, and testing phases, respectively. For the corresponding phases, SEM were also 51.8854, 52.2764, and 55.2572, respectively. According to sensitivity analysis, the most important input variable for prediction of SW was body weight at 20 D of age ( BW20 ), whereas the less important input variables were weight of the birds at hatch and body weight at 5 D of age. The results of the neural network optimization indicated that all the input variables, except for BW20, were very similar but slightly higher than mean values (μ for each input variable). The results of this study suggest that the ANN provides a practical approach to predict the final body weight (SW) of Japanese quails based on early performances. Moreover, phenotypic selection for higher values of early growth traits did not ensure the achievement of maximum SW, except for BW20.

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