Comparative Study of Growth Patterns for Three Strains of Broiler Chickens Using Mathematical Models

The aim of the current study was to investigate the growth pattern of three genetic strains of broiler chickens including Ross 308, Cobb and Arbor Acres by mathematical models. For this purpose, the body weight of 500 broilers for each strain was recorded weekly. Gompertz, Logistic and Richards functions were considered for data fitting. Three functions were compared by adjusted determination coefficient (R2) and root mean square error (RMSE). For all three models, R2 had high values, ranging from 0.987 to 0.999. The difference among the fitted functions by RMSE was significant compared to the R2. The Richards function had more appropriate description for the growth curve of the Cobb strain, because of having the minimum RMSE, 61.57 compared to 85.43 and 66.61, for Gompertz and Logistic functions, respectively. However, the Gompertz function with the maximum R2, and the minimum RMSE, 73.32 and 3237, respectively, was the most suitable function to describe the growth curve of Arbor Acres strain

Modelling the biological aspects of broiler breeding: integrated and non-integrated systems

The objective of present study was to derive the economic values for important traits   in broiler breeding program and to specify their sensitivity to production circumstances, using a deterministic bio-economic model, reflecting an integrated or non-integrated broiler chicken’s production system. Model focuses on multiplier breeder, hatchery, commercial grower and processor stages. The estimated economic values ranged from -0.2035 to 0.2318 for both integrated and non-integrated systems. The estimated economic values based on non-integrated system were higher than those of integrated system except for hatching   egg number (0.0009 vs. 0.0014), mortality (-0.0078 vs. -0.0068) and wings yield (0.0206 vs. 0.0158). In integrated situation, the effect of changes in the mean of hatching egg number, finishing weight and mortality on the economic values of traits was examined. The results showed that hatching egg number did not affect the economic values of traits at the preceding stages. On the other hand, changes in traits at the commercial grower, namely finishing weight and mortality affected the economic values of traits at both commercial grower and processor stages. The results of sensitivity analysis (± 20%) showed that traits at the multiplier and hatchery stages were sensitive to changes in feed costs at rearing and laying periods and also changes in the price of parental stock chicks, but the traits relating to commercial stage did not show any sensitivity to these factors. Among different factors, feed cost in commercial stage had the most impact on economic values of finishing weight, feed consumption and mortality

Prevalence and Correlates of Psychiatric Disorders in a National Survey of Iranian Children and Adolescents

Objective: Considering the impact of rapid sociocultural, political, and economical changes on societies and families, population-based surveys of mental disorders in different communities are needed to describe the magnitude of mental health problems and their disabling effects at the individual, familial, and societal levels. Method: A population-based cross sectional survey (IRCAP project) of 30 532 children and adolescents between 6 and 18 years was conducted in all provinces of Iran using a multistage cluster sampling method. Data were collected by 250 clinical psychologists trained to use the validated Persian version of the semi-structured diagnostic interview Kiddie-Schedule for Affective Disorders and Schizophrenia-PL (K-SADS-PL). Results: In this national epidemiological survey, 6209 out of 30 532 (22.31%) were diagnosed with at least one psychiatric disorder. The anxiety disorders (14.13%) and behavioral disorders (8.3%) had the highest prevalence, while eating disorders (0.13%) and psychotic symptoms (0.26%) had the lowest. The prevalence of psychiatric disorders was significantly lower in girls (OR = 0.85; 95% CI: 0.80-0.90), in those living in the rural area (OR = 0.80; 95% CI: 0.73-0.87), in those aged 15-18 years (OR = 0.92; 95% CI: 0.86-0.99), as well as that was significantly higher in those who had a parent suffering from mental disorders (OR = 1.96; 95% CI: 1.63-2.36 for mother and OR = 1.33; 95% CI: 1.07-1.66 for father) or physical illness (OR = 1.26; 95% CI: 1.17-1.35 for mother and OR = 1.19; 95% CI: 1.10-1.28 for father). Conclusion: About one fifth of Iranian children and adolescents suffer from at least one psychiatric disorder. Therefore, we should give a greater priority to promoting mental health and public health, provide more accessible services and trainings, and reduce barriers to accessing existing services

Direct and maternal genetic trend estimates for body weight traits of Iran-Black Sheep using multivariate animal models

The objective of the present study was to estimate direct and maternal genetic trends for body weight traits in IranBlack sheep using data which were collected for 24 years. The investigated traits were birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and yearling weight (YW). A multivariate animal model analysis was applied to predict the breeding values of individual for the studied traits. For each trait, genetic trends were obtained by regressing the means of predicted breeding values on year of birth. Direct genetic trends were positive and highly significant (P<0.01) for BW, WW, 6MW, 9MW, and YW and were 0.93, 43.74, 81.72, 87.29, and 137.61 g/year, respectively. Also, maternal genetic trend for BW and 6MW was significant and were 4.60 and -14.38 g/year, respectively. The results showed that improvement of body weight traits of Iran-Black sheep seems to be possible in selection programs

Birth weight and stillbirth genetic parameter estimation in a river buffalo simulated population

Stillbirth (SB) is a threshold character that has been detected as the most important factor affecting the future reproductive life of an animal. In buffaloes, stillbirth accounts for approximately 42% of all reproductive disorders being considered as the main reproductive disorder in buffalo calves. The present study aimed to estimate the heritability values and to determine the genetic and phenotypic correlation between stillbirth rate and birth weight (BW) using a Bayesian approach via Gibbs sampling method in a river buffalo population. A stochastic simulation was used to create a population in which random mating was used for 15 discrete generations. A bivariate animal model including maternal effects was used. Maternal effects were significant (p &lt; .05) for both BW and SB. The results showed that when the SB rate increased from 1% to 50%, the estimated direct heritability of SB increased. Yet, by increasing the SB rate from 50% to 99%, a decrease of the SB estimated direct heritability was observed. The genetic correlation between BW and SB was decreased by increasing the level of occurrence of SB in the population from 1% to 99%. The root mean square error (RMSE) of heritability was increased from 40% to 70% level of occurrence of SB. Based on findings, it can be concluded that to reduce stillbirth rate in the population, it is possible to use genetic improvement program and birth weight could be one of the main components of a selection goal