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An experiment was conducted to determine dietary energy (ME) and CP requirements of quail chicks using response surface methodology. A total of 40 floor pens of 20 birds each were assigned to 9 diets of central composite design (CCD) containing 5 levels of ME (2,809 to 3,091 kcal/kg) and CP (19 to 24.8% of diet) from 7 to 14 d of age. The experimental results of CCD were fitted with quadratic response models, and ridge analysis was used to compute the optimal response for BW gain (BWG) and feed conversion ratio (FCR). Regression analysis showed that the linear effect of independent variables was significant on bird responses. The quadratic and cross-product effects did not have significant effects on performance. Dietary levels of CP linearly affected BWG and FCR, but the effect of dietary ME was not significant. The ridge maximum analysis on BWG and minimum analysis on FCR models revealed that the maximum BWG may be achieved with 2,950 kcal of ME/kg and 25% CP; and minimum FCR may be obtained with 2,878 kcal of ME/kg and 24.4% CP. The results of this study showed that response surface analysis with the CCD platform was successfully used to optimize dietary requirements of Japanese quail and this methodology could be used for other nutrients.

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, ...

The optimization of dietary phosphorus (P) depends on precise details of the P availability in feed ingredients to avoid excess or deficient P in a mixed diet. This study was carried out to measure the apparent ileal digestibility of P for corn, wheat, soybean meal, and corn gluten meal in growing Japanese quails from 28 to 32 d posthatch. A total of 400 quail chicks were randomly distributed across 5 treatments with 4 replicates and 20 birds in each floor pen. The P-free diet (PFD) was formulated based on cornstarch to measure the basal endogenous P losses (EPL). Digestibility coefficients were determined by ileal digesta sampling using TiO 2 as an indigestible marker. The EPL was estimated at 384 mg/kg DMI. The apparent ileal P digestibility (AIPD) for corn, soybean meal, wheat, and corn gluten meal were determined to be 0.38, 0.53, 0.38, and 0.78, respectively. The corresponding values for true ileal P digestibility (TIPD) were 0.48, 0.61, 0.50, and 0.83, respectively. The t -test analysis showed that the difference of AIPD and TIPD values for corn ( P = 0.031) and wheat ( P = 0.015) were statistically significant, however, no significant differences were observed for corn gluten meal ( P = 0.318) and soybean meal ( P = 0.104). In conclusion, the correction of AIPD coefficients for EPL in low-P ingredients such as corn and wheat may be much more important than that in high-P feedstuffs such as corn gluten meal and soybean meal in growing quails.

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