جستجوی مقالات مرتبط با کلیدواژه « Growth curve » در نشریات گروه « علوم دام »

This study was aimed to optimize the suitable slaughter weight of Afshari fattening male lambs by using the feed conversion ratio curve and carcass tissue composition. Thirty-two Afshari male lambs, averaging 105±15.0 (SD) days of age and initial body weight of 30.2±3.6 (SD) kg, from the commercial herd in the Animal Science Research Institute of Iran were used. Metabolizable energy (ME) contents were, 2.79, 2.78, 2.72 and 2.69 Mcal/kg dry matter (DM) and crude protein (CP) contents were 146, 128, 109, and 103 g/kg for the 1, 2, 3, and 4 diets, respectively. The results showed, DMI and feed conversion ratio (FCR) had an increasing trend, with the increasing length of fattening period. The daily weight gains, had an upward trend from the beginning of the experiment to the 56th day, and then it decreased with a relatively small slope. Dressing percentage increased, with increasing length of the trail, so that it was significantly higher in the last stage of slaughter (55.3%) than the previous (52%). Weight percent of digestive tract (stomach and intestine), liver and, lung decreased but weight percent of internal fat increased, with a significantly difference, when experimental period increased. The highest percent of fat-tail weight, was observed in the last stage of slaughter (19.8) and the lowest was observed in the first stage of slaughter (14.2). Back fat thickness increased with increasing length of the experiment, so that a significant difference observed between the last stage of slaughter and the previous stages.

The growth models own a very great importance in biological systems.  For example, by analyzing the growth curve of ruminant animals and poultries, it is possible to fastener and to manage their rearing, nutritional and behavioral requirements, based on their growth routines and principles. On the other hand the growth pattern of animals might be used in evaluating their genetic potential for breeding purposes. Thus, to evaluate and describe the growth pattern of Japanese quail, this study aimed to evaluate the capabilities and advantages of non-linear and nonlinear mixed models to describe and evaluate the growth pattern of Japanese quail.

In order to assess and designate the growth pattern of Japanese quail, we used the growth data of three groups; high weight (HW), low weight (LW) and the control lines of Japanese quail. Different models, including logistic, Gompertz and Richard's both non-linear and nonlinear mixed models were fitted to the data. For evaluation of models three criteria including coefficient of determination (R2), mean square error (MSE) and Akaike's information criterion (AIC) were employed as criteria to compare the mentioned six different models.

Values of the coefficient of determination (R2), for logistic, Gompertz and Richard's nonlinear models were 0.954, 0.957 and 0.951, mean square error (MSE) for three models were 74.034, 72.560 and 72.730, and Akaike's information criterion (AIC) for the models were 65829, 65307 and 65349, respectively. The results for non-linear mixed models, in the same order mentioned above and for R2, MSE and AIC, were 0.976, 0.978 and 0.978; 33.400, 31.658 and 31.849; 61449, 60641 and 60591 respectively.

The results showed that nonlinear mixed models had higher accuracy and less mean square error, compared to nonlinear models and Richard’s model is more capable (better) to the predict growth pattern of Japanese quail. Also among non-linear models Gompertz model had a better fit to the purpose. In general it can be said that the parameters determined by the functions inspected in this study, are not much different.

The aims of this study were to estimate variance components, prediction of genetic parameters and correlations of growth curve parameters of nonlinear models such as Broody, Gompertz, Logistic and von in Kurdi sheep breed. Data comprised of 17659 body weights from birth to yearling of 5074 lambs belonging to 162 rams and 1968 ewes from 1996 to 2013. Growth parameters were estimated by NLIN procedure of SAS V.9.4., and parameters including A, B and K were calculated by individual fit according to the sex of the animal. Variance components were estimated by a mixed model of BLUPF90 and considering the influences of fixed effect including sex, birth type, year and month of birth. Heritability of mature weight was low in all models (0.05 to 0.09) and showed the low participation of genetic variance from the phenotypic variance. Therefore, to achieve the desired genetic gain and high accuracy, more records of lamb growth parameters are required for each ewe and ram, as well as, the improvement of environmental circumstances. Regarding high positive genetic and environmental correlations of A-B, it is expected that selection of animals with higher birth weight or improving the environmental circumstances, lead to a height mature weight, which needs more investigation over the increasing of lambing ease. The medium and negative genetic and phenotypic correlations between A-K imply the negative relationship between the mature rate and weight.

The present study aimed to determine the best mathematical model to describe the growth curve of dromedary camels. For this purpose, the data recorded between 1990 and 2018 in the National Research and Development Station on Dromedary Camel located in Bafgh, Yazd province, were used. The records included the body weight of 747 dromedary camels at different ages (from birth to 14 months of age). To determine the best model describing the growth curve of dromedary camels, eight different mathematical models including linear, quadratic, cubic, Gompertz, Brody, logistic, monomolecular, and von Bertalanfy were compared. The age of camels was included in the model as an independent variable and the weight of camels as a dependent variable. The criteria for comparing the performance of the models were having the highest value of the corrected coefficient of determination (R2 adj) or the lowest values of Akaike information criterion (AIC) and the mean square error (MSE). Based on the results of this study, the accuracy of linear, quadratic, and cubic equations in describing the growth curve of dromedary camels was significantly lower than that of Gompertz, logistic, monomolecular, von Bertalanfy and Brody models. The results of the present study showed that the weight of dromedary camels could be predicted precisely up to weaning age (200 days), However, after weaning, due to the effect of different environmental conditions on the growth of camels and a sudden change in feed type, the increase in camel weight does not have a linear relationship with their age, and it is better to use other parameters such as biometric measurements to accurately estimate camel weight.

The traits of economic importance such as body weight at different ages and growth rate in sheep are used as selection criteria in breeding programs. Growth can be defined either as an increase in the number of body cells or an increase in body weight and volume over a period of a lifetime. Animal growth curves can be described using various mathematical models. Growth curve components are heritable in different species. Therefore, the genetic potential of animals can be predicted for growth curve components. The best function describing the growth curve can vary depending on the breed and population under study. The aim of the present study was to investigate the ability of different nonlinear models to fit the growth curve of Moghani sheep and to estimate the genetic parameters of the growth curve characteristics in this breed.

In the current study, the data related to the body weights of Moghani sheep collected at the Moghani sheep breeding station in Jafarabad, Moghan, during the years 1989 – 2016 were used to investigate the growth curve and estimating the genetic parameters of the growth curve characteristics in this breed. Four nonlinear models including Brody, Logistic, Gompertz and von Bertalanffy were used to describe the growth curve of Moghani sheep. All models were fitted on the body weight records of animals at different ages using the NLIN procedure of SAS 9.0 software. The models used have three components including A (maturity weight), B (initial weight of animal) and K (maturity rate). Goodness-of-fit indices including coefficient of determination (R2), Root-Mean-Square Error (RMSE) and Akaike information criterion (AIC) were used to select the best model. After fitting the nonlinear models and selecting the best model, the components of the growth curve of individual animals were estimated using the best nonlinear model. Then, non-genetic factors affecting the growth curve components were investigated using the GLM procedure of SAS. Six univariate animal models that differed in terms of maternal permanent environmental effects and maternal genetic effect as well as covariance between direct and maternal genetic effects were used to analyze the traits. Also, three bivariate analyzes between growth curve components were performed to estimate the genetic correlation between traits.

According to our results, the logistic model with the lowest MSE and AIC and the highest R2 was the best model to describe the growth curve of Moghani sheep. The estimated values for the maturity weight (A), initial weight of animal (B) and maturity rate (K) by the logistic model were 40.328, 7.582 and 0.0270, respectively. The fixed effects of lamb sex, birth type, year and month of calving as well as dam age at calving had a significant effect on the components of the growth curve. Between the six fitted linear models, models number six, two and four were selected as the best models to analyze the components of maturity weight (A), initial weight of animal (B) and maturity rate (K), respectively. Direct heritability for maturity weight (A), initial weight of animal (B) and maturity rate (K) were estimated to 0.17, 0.08 and 0.19, respectively. Estimates of genetic correlation obtained from bivariate analysis between A-B, A-K and B-K were 0•06, 0•03 and −0•0003, respectively.

Among the four nonlinear models used, the logistic model had the best fit for the growth of Moghani sheep. According to the results of our study, the growth curve components of this breed had an acceptable heritability, so that these traits could be used in breeding programs to alter the growth curve and improve the growth pattern of animals in this breed.

 The Makooei sheep is a medium-sized, fat-tailed breed, carpet wool and white color breed. This breed dispreads mainly in the north west of the Iran in West Azerbaijan province. This sheep breed is called White Karaman in Turkey. Growth curve is the graph of weight as a function of age on time. The changes taking place in animal's body weight with the passage of time that is often sigmoid in shape. Further, information on the growth pattern helps determine feeding and management plans and planning breeding strategies to improve the efficacy of whole growth process. Using growth models is one of the ways that can be used to predict and measuring animal’s performance, such as weight gain. In fact, growth models are linear or nonlinear regression functions that can predict growth at different ages of animal life. Non-linear mathematical functions, empirically developed by depicting body weight against age, have been appropriate to characterize the growth curve in different animal classes. Therefore, the objective of this study was to describe the growth curve of Makooei sheep using non-linear models. The Negative exponential, Brody, Gompertz, Logistic and von Bertalanffy models were used to evaluate their efficiency in describing the growth curve of Makooei sheep.

The used data included 5913 body weight records from 1966 male lambs and 7092 body weight records from 2354 female lambs (from birth to 225 days), collected during 1993 to 2011, at the Makooei Sheep Breeding station, in West Azerbaijan, Iran. In the station, each ram was randomly mated to 10-15 ewes. Lambing was in January and March and lambs were weaned until ~3 months of age. The lambs were weighed and ear tagged after birth.  Data were checked several times, so defective and out of range records were deleted. The Negative exponential, Brody, Gompertz, Logistic, and Von Bertalanffy functions were fit to the data to model the relationship between weight and age. Each model was fitted separately to body weight records for all lambs, male and female lambs using the NLIN procedure in SAS 8.2. The non-linear mixed models were examined for goodness of fit using Adjusted Coefficient of Determination (R2adj), Root Mean Square Error (RMSE), Akaike’s information criterion (AIC) and Bayesian information criterion (BIC). Finally, the best model was selected with the highest R2adj and the lowest RMSE, AIC and BIC.

 All non-linear models showed good capacities of fitting for describing the growth curve in Makooei sheep. The R2adj for the Brody model was found the highest (0.8799) and the lowest for Logistic model (0.8505) for all lambs. The A parameter is an estimate of asymptotic weight which can be interpreted as the weight at maturity. For the studied dataset the highest and lowest values for the parameter A were obtained by Brody model (for all lambs = 39.04) and logistic model (for all lambs = 32.08), respectively. The parameter B represents an integration constant, related to the initial animal weight but lacking a clear biological interpretation. The highest and lowest values for the B parameter were obtained in Logistic model (for all lambs = 6.28) and Von Bertalanffy model (for all lambs = 0.52), respectively. The parameter k that defined the maturation rate is another important feature to be considered, since it indicates the growth speed to reach the asymptotic weight. Therefore, animals that have higher k values will reach puberty sooner. The estimate of k was highest in the Von Bertalanffy model (for all lambs = 0.10), while Brody (for all lambs = 0.01) and Negative exponential (for all lambs = 0.01) models showed lowest values. The results of this study showed that the Brody model with the highest R2adj and the lowest RMSE, AIC and BIC was able to describe the growth curve better than other growth models in Makooei sheep. In growth curve the most important biological relationship has been found between A and k. The lowest and highest correlation between the two parameters of A and k for all lambs was found for the logistic (-0.59) and Brody (-0.97) models, respectively.

 The results of this study suggest that the Brody model can be useful for set some management strategies such as determining nutritional programs and the appropriate age for slaughter of Makooei sheep

For doing this study 6841 body weight records at different ages of 1877 Makooei sheep which were collected at Makooei sheep breeding station in Maku city of West Azarbaijan province was used. Parameters of growth curve based on body weight at different ages and different initial amounts using NLIN procedure of SAS software were estimated. Four non-linear models including Brody, Von-Bertalanffy, logistic and Gompertz, were fitted on data. After setting the most appropriate describing non-linear growth curve, using by Gauss-Newton repeat method fitted in way that growth curve parameters obtained separately for all individuals. Using GLM procedure of SAS software, effective fixed effects on these parameters were identified. The Brody model with having the highest accuracy (R2 = 0.955432) and lowest error (MSE = 37.78) was recognized as the best model for describing growth pattern of Makooei sheep. The year and season of birth, lamb sex and birth type had significant effect on mature weight and growth rate (P < 0.01) but lamb sex on mature rate was not significant (P < 0.01). The results showed that, compared with the other evaluated models, for fitting growth curve of Makooei sheep was more suitable.

The objective of this research was to compare the growth patterns of commercial broiler chickens, native chickens and domestic pigeon raised in Iran. The growth curves and their parameters were estimated by the Richards function. Body weight data of mixed-sex of commercial broiler chickens (n=326000), native chickens (n=244000) and pigeon (n=4000) were used. Birds were fed ad libitum and weighed in alternating periods on their life. The accuracy of the curve fit was high in all species (R2 = 0.996 to 0.970). The y+/A ratios (weight at the inflection point over mature weight), which determine the shape of the growth curve, were 0.358, 0.379 and 0.352 in chickens, native birds and pigeons, respectively. The age at the inflection point confirmed the high early growth of pigeons (t+ = 10.2 d) and chickens(t+ = 36.6 d). The phenotypic correlations between the inflection parameters t+ and y+ were higher in commercial broiler chicken than native and pigeon. The inflection parameter t+ and y+ were positively associated with the maturing index k in all birds, in this way, the evolutionary aspects are discussed. In practical view, these results could be used to develop the production strategies for native chicken breed and domestic pigeon to positively affect the growth parameters, efficiency as well as conservation of local genetic resources.

This experiment was conducted to determine the nutritional effects of dietary inclusion of a commercial local-produced probiotic (Bio-Poul®) on parameters of broiler growth curve. In this way, the fitting and prediction abilities of three models including the Gompertz, Logistic and Richards were compared. A total of 280 one day-old Ross chicks were used in a completely randomized design with four treatments and five replicates each (pens with 14 birds of both sexes male and female in equal numbers). Four dietary treatments containing 0, 100, 200, and 300 grams of Bio-Poul® probiotic per ton of feed were fed. To estimate the growth characteristics of birds, the weekly body weight of chickens from 0 to 42 days of age was recorded and fitted to the three growth models. Prediction abilities of the models in describing the growth of chickens were tested using goodness of fit indexes such as coefficient of determination (R2), root mean square error (RMSE), bias and a standard F test. Based on calculated indexes values, it was found that the Richards model had better prediction in compared with Gompertz and Logistic models with R2 value of 0.9998, RMSE of 9.16 g and bias of 0.52 g. In addition, the results of the pairwise comparison by F test showed that the Richards model was also more accurate in predicting growth of birds. In conclusion, the results showed that the diet containing 200 grams of Bio-Poul® probiotic may help to obtain optimum growth response and improve growth rate in broiler chickens.

The objective of this study was to select the best model among five non-linear growth functions, i.e., Brody, Gompertz, Logistic, Von Bertalanffy and Negative exponential for describing the growth curve in Markhoz goat. The data included 5557 body weight records of goats from birth to yearling which were collected during 2006 to 2013 at Sanandaj Research Station. Growth curve parameters (A, B, K) were estimated by the NLIN procedure of SAS program and in order to compare different models for selecting the best model, statistics of coefficient of determination (R2adj), Akaike´s Information Criterion (AIC), Bayesian Information Criterion (BIC), Root Mean Squares Error (RMSE) and Durbin-Watson were calculated. For all animals, Logistic model was the best model as provided the greatest R2adj and the lowest values of RMSE, AIC and BIC than other models and this model could indicate the best prediction of growth in Markhoz goat. The best selected models for predicting growth of males and females were Brody and Gompertz models, respectively; and Logistic model was selected as the best model for both singles and twins. The negative exponential model provided the worst fit of growth curve for all animals, males, females, singles and twins. Logistic model can provide the best prediction of growth pattern of Markhoz goat over a definite time period.

This research was conducted to study genetic and phenotypic relationships between growth curve parameters in Mehraban sheep. The data set used in this study were obtained from the Agricultural Organization of Hamedan province and comprised 35414 body weight records from birth to 365 days of age during 2001to 2011. Parameters of Brody growth model were studied which included A (asymptotic mature weight or average mature weight of animal), B (proportion of asymptotic mature weight to weight gain as a percent of mature weight) and K (growth rate until reaching to mature weight). Fixed factors affecting on growth curve parameters were identified using the GLM procedure of SAS software. The model of genetic analysis included direct genetic effect, maternal genetic effect, maternal permanent environmental effect and covariance between direct genetic and maternal genetic effects. To estimate genetic relationship between growth curve parameters, Bayesian method based on Gibbs sampling was used. Direct heritabilities for growth curve parameters of A, B and K were 0.29, 0.63 and 0.27, respectively. Direct genetic correlation between A and B was positive and high (0.58), which indicates that these traits are aligned with each other while the correlations between B and K (-0.69) and between A and K (-0.54) were negative. The results indicated that improvement of growth curve parameters of Mehraban sheep is possible in selection programs. Therefore, it is worthwhile to propose an optimum selection strategy for obtaining appropriate growth curve in Mehraban sheep through changing genetically the model parameters.

In this experiment, 1032 one-day-old Japanese quails were randomly divided into 4 dietary treatment groups with 3 replicates of 86 quails in each. The treatment groups were: 1) group with low dietary nutrient concentration [95% of nutrients recommended by NRC (1994), -5% NRC], 2) group with medium dietary nutrient (DN) concentration [100% of nutrients recommended by NRC (1994)], 3) group with high DN concentration [105% of nutrients recommended by NRC (1994), % NRC] and 4) group with very high DN concentration [110% of nutrients recommended by NRC (1994), % NRC]. Feed intake was affected by dietary treatments only during 0-21 d period, with a lesser of feed consumption for group 1 compared to the other groups. Body weight gain was increased in harmony to the nutrient concentration in all phases of the experiment. The best feed conversion ratio was achieved by % NRC. Except for the relative weights (% of live weight) of thigh muscle, pancreases and gizzard, there were no significant differences between the dietary treatments for other carcass parts. According to the Gompertz function, asymptotic weight (Wf) was higher in % NRC (295 g) than the other dietary treatments (269, 292.7 and 290 g for -5% NRC, NRC and % NRC, respectively) as was the case with growth rate constant (b: 0.059, 0.059, 0.061 and 0.061 for -5% NRC, NRC, % NRC and % NRC, respectively). The range of age and weight at point of inflection were from 19.7 to 20.8 d and 99.3 to 108.7, respectively.

Growth traits in farm animals are of great economic importance. Today, growth rate, body weigh changes at different stages of the life, is considered as an important trait in animal breeding. Growth process can be described by a nonlinear function. In the present study, to describe the growth curve of different breeds of Iranian sheep, Gompertz nonlinear function was fitted on body weight records of 134,798 lambs (born between 1985-2010) from birth to 72 months of age. The lambs were progeny of 5,198 rams and 82,577 ewes in a total of 541 flocks. Growth curves of the breed, year and season of birth, sex of lamb, type of birth and dam age were predicted by using estimated parameters of the function. The findings showed Lori-Bakhtiari and Kermani breeds had highest (37.126 kg) and lowest (21.078 kg) mean body weight, respectively. Male lambs were found to be heavier than female lambs (29.956 kg vs. 27.921 kg). Older ewes (parity five and over) had heavier lambs than that of the younger ewes. The highest and lowest mean body weights were obtained for singleton (28.812 kg) and triplet (27.036 kg) lambs, respectively. Gompertz could provide a descriptive comparison for animal growth and to be utilised for predicting growth rate.

An experiment was carried out to estimate growth parameters of broiler chickens received Artichoke extract in their drinking water using Gompertz non-linear model and to compare Gompertz non-linear regression equation and artificial neural network modeling in terms of their ability to predict body weight of broiler chicks at day 42 of age. A total number of 250 one- day- old Ross 308 broiler chicks were used. The chicks received Artichoke extract in their drinking water at the doses of 0، 100، 200، 300 and 500 mg per liter. The birds were weighed at days 1، 2، 7، 14، 21، 24، 27، 30، 33، 35 and 42 of experimental period after 3 hours of fasting. Estimated mature body weight was significantly higher in birds received 200 mg/liter Artichoke extract in drinking water than the other birds (P<0. 05). The chicks received 200 mg/liter Artichoke extract in their drinking water had a significantly higher coefficient of relative growth compared to the control group and those received 300 mg/liter Artichoke extract (P<0. 05). The goodness of fit in terms of R2 values of the artificial neural network (ANN) model showed a higher accuracy of prediction for body weight of broiler chicks at day 42 of age than the equation established by Gompertz model (0. 998 vs. 0. 997، respectively). Because mean square error (MSE)، mean absolute deviation (MAD)، mean absolute percentage error (MAPE) was lower in the ANN than in Gompertz model، it estimated body weight of birds at day 42 of age better than did Gompertz model.

The aim of present study was to investigate different aspects of growth by using the growth curve in a paternal line of broiler chicken. In this study 299 male birds from the parental lines (A & B) of Arian strain broiler chicken were used to investigate the growth curve under two treatments of control and ascites. At 35 days of age، the blood parameters and hematocrit value were measured just on 15% of birds. Food conversion ratio between 23 and 54 days of age were studied on 20% of birds individually. The body weights were measured individually at 1، 4، 7، 10، 14، 17، 21، 28، 35، 42، 49 and 54 days of age. Moreover at the end of experiment، all the birds were slaughtered and then the right ventricle to total ventricle ratio was assayed. There was significant differences (P<0. 05) for oxygen saturation between two treatments in the paternal lines but no significant difference was observed food conversion ratio between the treatment in parental line (P>0. 05). The ratio of right ventricle to total ventricle of the birds with induced ascites was significantly (P<0. 05) in both lines. Furthermore the results of current study showed that there was significant differences (P<0. 05) between two treatment for mature index and age at in inflection point just in line A. indeed، mature index increased and age at in inflection point decreased in ascites treatment.

In order to investigate the growth curve of broiler chickens at line level, respectively 154 and 144 birds from two paternal lines A and B of a commercial broiler line were used. Line A were selected several generations for low feed conversion rate and line B were selected several generation for high body weight. Body weight was measured at 1, 4, 7, 10, 14, 17, 21, 28, 35, 42, 49 and 54 days of age and the growth curve were fitted by Gompertz model. Moreover, feed conversion rate were evaluated just for 20% of birds within 23 and 54 day of age. At the end of experiment, all birds were slaughtered and some carcass traits like breast weight, liver and abdominal fat were assayed. The results of current study showed that mature index and the age at inflection point in male birds of line B were higher than that in line A. Female broilers in line B showed higher hatch weight, mature index and age at the inflection point than that in line A. The hatch weight, mature index and age at the inflection point were similar between male and female birds in both paterntal lines. Liver weight, abdominal fat and feed conversion rate among male birds in paterntal lines were no significant, but the difference in breast weights in male broilers was significant. Breast weight, Liver weight and abdominal fat in female broilers in line B were significant and higher than female broilers line A but food conversion rate was no significant. Liver weight and abdominal fat were significant between males and females in parental line but, only breast weight between male and female in line B was significant. The growth rate of birds in line B during 17 to 35 day of age was higher than that in line A. Moreover the growth rate in male birds during 17 to 54 day of age was higher than that in female birds.