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

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.

Cashmere is a very fine fiber that is produced by secondary hair follicles in cashmere goat. Based on American test and material association description, cashmere is fine fiber in Asian Indian goat hair follicles with diameter lower than 30 microns. Cashmere is growing as “under coat” in cold season and it shedds during the time from late winter until early spring. It is estimated that 68 goat breeds produce cashmere fibers in the world. Cashmere goats are originated from Asia. The important countries that can produce a large amount of cashmere are China, Mongolia, Iran, Turkey, and India. Total production of cashmere is estimated to be 5mt. During the last decades, due to the economic importance of cashmere, USA, Australia, and NewZealand joined to the cashmere producing countries. Many researchers reported that cold climate is suitable for production of quality cashmere. In this research, effects of nutrition and age on histological characteristics of Raeini Cashmere goat were studied in Tabriz, East Azerbaijan.

For this research, 24 female Raeini cashmere goats were selected. The goats were selected from Baft Raeini cashmere goat breeding and husbandry station. Goats were fed individually   and were treated for 8 months of study based on feeding levels (Maintenance, 0.7 M, 1.4 M, and 1.8M) and age (6 months and 18 months) on fleece growth. The trial was conducted at the khalat-Pushan Research Station, University of Tabriz. The goats allocated to four feeding levels: M (goats fed to maintain live weight, 0.7M (goats fed to lose 3Kg live weight from February to September), 1.4M, and 1.8M (goats fed to gain live weight). Patches of fleece from defined areas were repeatedly shorn at 4 weekly intervals from the right mid side of each goat. For follicle study, in the fist, 120cm2 of left side of animals was marked firstly; then, these region fibers shaved by electrical shaver. Shaving was repeated monthly (for four weeks). Skin biopsy was taken monthly from left mid side of skin of abdomen. samples were fixed in 10% formalin. Paraffinized block were prepared and then, they are sectioned as serial section in 8-micron thickness. Histological sections were stained by sak pic method (reference ????). Results were analyzed by analyses variance and paired t-test.   

This research results, showed that there was no significant effect of feeding level or age on weight of cashmere and hair per area, secondary follicle activity, cashmere length, and yield (P<0.05). Fleece and live weight for young goats were significantly less than that of old goats (P<0.05). Result were appeared that mean cashmere diameters of patch shorn in September of goats fed M, 1.4M and 1.8M were significantly greater than that of goats fed 0.7M (P<0.05). In group feeding more than maintenance requirements, results indicated no increase in cashmere production. Average fiber diameter of cashmere in June was higher than in May. Results of this research indicated that there are not any significant differences between different levels of feeding and age on fiber growth rate (P<0.05). The highest fiber production and the maximum mean of fiber growth rates (1.64 and 1.48 g/120cm2 / 28 days) were observed in June and July. Secondary to primary follicle ratio of all goats was 12.60. Study of secondary follicles ratio showed that different levels of feeding cannot reduce number of secondary follicles. Many researchers reported that increase in feeding levels to over maintenance rate cannot increase cashmere growth rate. This research results confirmed by previous studies. it was reported that feeding limitation can reduce diameter of cashmere, but there is not any increasable effect during over maintenance feeding and an increase in dietary protein. This research indicated that cashmere diameter was more in two-years old goat than one-year old goat cashmere diameter. These   results were similar with reports of Klor et al. (1993), Rafat (1997), and Salehi (1997). Increase in diameter of wool fibers with increasing in the age of animals was reported in sheep and goat. In other studies, it is shown that effect of age on diameter of Norway cashmere goats was significant (P<0.05). Results of our research show that diameter of cashmere in Raeini goats increases at June. Similar results are illustrated in Kerman (with the same age and sex). The weight of produced fibers / body surface was the same in four feeding treatment groups, but diameter of cashmere was different. Numbers of secondary follicles   increased in April. Minimum weight of fibers was observed in April in all of the treatments, which may be because of low activity of follicles in this month. Variation of cashmere diameter and cashmere growth rate can explain differences in total cashmere production. Changes of feeding level from under maintenance to high levels cause increase in cashmere diameter. This study appeared that diameter of cashmere fibers can have reaction to feeding rate. Accordingly, energy has important effect on growth of hair and cashmere. The animals with low energy diet produce low amount of cashmere, Other researchers have opposite idea. According to their statement, there are not any difference in partition for nutrient between primary and secondary follicles. This research result showed that increase feeding cannot increase cashmere production. Jia et al (1995) reported that increase of diet net protein has not any important effect on cashmere goats production in Spain. In other study using unpregnant goat it has been indicated follicular activity and fiber growth is not under influence of pregnancy and milking. However, some researches showed that reproduction condition of animal, as pregnancy and milking, has effect on cashmere fiber growth.  

Generally, results of this study showed Raeini cashmere goats in East – Azarbayjan climate did not show any fundamental changes in diameter and length of cashmere in comparison with Raeini cashmere goats which reared in Kerman province.

Trend in body weight, thyroid hormones and some blood metabolites changes in broiler breeder hens after the peak egg production was studied. Blood samples from 20 Ross 308 broiler breeder hens, were investigated from 47 to 55 weeks of age. Plasma lipid profile including cholesterol, triglyceride, lipoprotein LDL, lipoprotein HDL, and also glucose concentrations were measured every two weeks, and plasma concentrations of triiodothyronine (T3) and tetradothyronine (T4), aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) were measured at the beginning and at the end of the experimental period. Results showed that body weight and plasma concentration of glucose, triglycerides, cholesterol, and LDL were increased, and concentrations of HDL were decreased (P<0.05) over the experimental period. Plasma T4 concentrations were decreased with age of the birds (P<0.05), while T3 concentrations were not affected. Plasma GOT and GPT enzymes activities were increased over the experiment period (P<0.05). In general, by increasing of age and subsequently body weight of breeder hens, several major changes have been occurred in blood metabolites and metabolic hormones which could reduce production and reproduction of broiler breeder flocks.

This study was conducted to determine the amylase gene expression in liver and pancreas tissues of broiler chicks fed with two levels of oak acorn(OA) fruit. A total of 264 broiler chicks were fed a control diet (without oak) and diets containing 15 and 20% OA. At the end of starter and finisher period, 6 birds from each treatment were randomly selected and Tissue samples were taken from their pancreas and liver. REST and SAS software were used to analyze gene expression. The 2004 Bestkeeper software was also used to determine the sustainability of β-Actin gene expression. Results showed that β-Actin gene was not affected by sex, age and experimental treatments. Thus, it was used to normalize the gene expression data. At 21d of age, the level of mRNA of the pancreatic amylase gene was significantly higher in broilers fed with 15% OA compared to the control group (p<0.05). On d 42, significant differences in expression of liver and pancreas amylase gene were not observed (p>0.05). Also, feeding birds with diet containing 20% OA increased the relative weight of pancreas (p<0.05). In conclusion, the results showed that amylase gene expression in birds fed diets containing 15% OA significantly increased at 21d of age. In other cases, genes expression was not influenced by experimental treatments.

The Japanese quails are blessed with many desirable characteristics, viz, faster growth, early sexual maturity, high rate of egg production (300 egg/annum), short generation interval (3-4 generations a year), small floor space, less feed requirements (20-25 g/adult bird/day), short incubation period of hatching eggs, less feed cost, and less susceptibility to common chicken diseases (Ernst, 2000). In consequence and due to shortage of available data on nutrient requirements of quails, prediction of biological responses of this type of poultry to nutrients using growth functions seems to be beneficial. Growth modeling are also critical for the understanding and formulation of breeding plans because they shift in response to selection (Marks et al. 1988, Mignon-Grasteau et al. 1999, Aggrey 2003 and Beiki et al. 2011). The representation of biological concepts through the simulation of growth dynamics enables us to better adapt management and nutrition to the requirements of the animals, while taking into account the interaction between genotype, nutrition and environmental conditions [Torres and Ferket 2012]. Eleroğlu et al. (2014) pointed out that the application of mathematical functions to describe the growth of birds was useful in estimating production termination deadline and formulation of appropriate feed mixtures (Michalczuk et al. 2016). Ersoy et al. (2006) claimed the Gompertz and Richards models to be the most appropriate for the characteristics of the growth of chickens, ostriches, turkeys and emus. Conflicting concluding by various authors upon the use of the same functions may result from the use of different genetic groups of birds in experiments. The objective of the present study was 1) to determine the best predictive growth function in describing data from Japanese quails and 2) to investigate the effect of dietary nutrients density on the growth curve parameters estimated by the growth models.
Material and One thousand and fifty one-day-old Japanese quails were randomly divided into 4 dietary treatment groups with 3 replicates of 86 quails in each in order to compare four growth functions (Gompertz, Richards, von Bertalanffy and Lopez) for their predicable abilities in describing growth of Japanese quails. The treatment groups were: 1) group with low dietary nutrient density [95% of nutrients recommended by NRC (1994), -5% NRC], 2) group with medium dietary nutrient density [100% of nutrients recommended by NRC (1994)], 3) group with high dietary nutrient density [105% of nutrients recommended by NRC (1994), % NRC] and 4) group with very high dietary nutrient density [110% of nutrients recommended by NRC (1994), % NRC]. Body weights of the birds were measured weekly over the 56 day of the experimental period. Evaluation on the goodness of fit for the models were made by R2, AIC, BIC, and RMSE criteria.
Evaluation on the goodness of fit for the models using R2, RMSE, AIC, BIC criteria showed advantage for the Richards in describing the growth data of Japanese quails which can be related to the variable point of inflexion in the Richards model and therefore its flexibility. According to the four growth functions considered, estimated final body weights were higher in the high density than the low density diets. The age at point of inflection were earlier in high versus low density diets. As early as 1945, Brody suggested that it was possible to select on the shape of the growth curve. A phenotypic modification of the growth curve was also observed in previous studies. Marks et al. 1988, Mignon-Grasteau et al. (1999), Aggrey 2003 and Beiki et al. (2011) showed that growth curve parameters were heritable. However, data shortage of the nutritional requirement necessary for quail breeding makes the mathematic simulation methods very useful in estimating the biological answer to the food nutrients contribution. The method of mathematic simulation of growth using growth functions can also provide the response of the growth parameters to nutrition (Daren and Marks 1988; Marks 1991; Gebhardt-Henrich and Marks 1993) which has the potential benefits when used for selection.
In summary, it was concluded that data regarding the growth parameters of quails would be best interpreted with the use of the Richards model. Meanwhile, since almost all the growth parameters estimated by the models were affected by the dietary nutrients density, therefore special attention needed will be given to the nutrition when selecting the quails as parental for the next generation through parameters estimated by mathematical simulation using growth functions.

Various factors, including photoperiod, temperature, nutrition, Body condition and age, are responsible for reproductive behaviors of animals. Environmental, physiological and social factors regulate the onset and sustain of reproductive season. Photoperiod and temperature are key environmental factors, but the first one is more important (Hafez and Hafez 2009). The regulation of reproductive activity by phototherapeutic messages due to secretion of melatonin from the pineal gland in most mammals has been reported, but this relationship is not well known in the horse (Diekman et al., 2002(. Regarding the role of the melatonin hormone in the reproductive process, in this study the aim was to investigate the changes in the concentration of the serum melatonin hormone in the Arab stallion, in three age groups including 2 to 6, 6 to 10 and 10 to 14 years old. The study was conducted under natural photoperiod in the seasons of the summer and winter in the Dezful region.
Material and This research was carried out using 33 Arab stallions in three age groups including 2 to 6, 6 to 10 and 10-14 years old under the same nutrition and management condition in the July and January (2012) were as the representative of the heating and cold season, respectively. The experiment done in the Arab horse breeding fields of Dezful. The concentration of melatonin from serum samples was measured by HPLC (Bechgaard et al 1998; Itoh et al 1999; Peniston-Bird et al 1993 and Gupta et al 2006). The results of this research were analyzed using SPSS software (version 18). Comparison of serum melatonin concentration between the summer and winter seasons done by T-test. The difference of these parameters in two seasons, and in three age groups 2 to 6, 6 to 10 and 10 to 14 years old was analyzed with one-way ANOVA and multi-domain tests Duncan.
The results showed that mean serum concentration of melatonin hormone in winter (97.39 ± 16.4 pg/ml) non significantly was higher than summer (20.11±12.3 pg/ml). Research (Casao et al 2010; Altinsaat et al 2009; Elkon et al 2011; Wrench 2007; Cigdem et al 2009; Gerlach and Aurich 2000; Nagy et al 2000 and Guerin et al 1995) on changes in melatonin hormone and seasonal reproduction of Horse, were considered 8 hours of difference during the day between summer and winter seasons, as a factor for significant changes in the concentration of melatonin hormone and horse reproductive activity. Since, in the city of Dezful, the difference in the length of the day in summer (July) and winter (January) is approximately four hours, it can probably be argued that the difference in the length of the day (the duration of lighting) in The hot and cold season is not such as to make a statistically significant difference in the level of serum melatonin of Arab stallion between two seasons. The results indicate that the season has affected on the level of blood hormones, sexual behavior, physical and biochemical properties of semen and its fertility (Hafez and Hafez 2009). In addition, reproductive activity of the horse throughout the year continued with the fact that the size of the testicles, the number of Leydig cells, testosterone concentrations, and therefore the volume and concentration of sperm in the winter, decreased (Wrench 2007). In this study, in both seasons, the mean concentration of melatonin in the 2 to 6 year old stallion was significantly more than 6-10 years old and 10-14 years old (P Due to the shorter photoperiod in winter than summer, a rise in the level of melatonin in this season was seen, but photoperiodic changes between the two seasons are not so significant that the melatonin hormone exhibits significant changes. Therefore, it can be said that in the Arab stallion, the season has no effect on the concentration of serum melatonin, but it decreases with increasing age of melatonin concentration.

Introduction; Evaluation of mineral concentrations in blood (Biricik and Ocal 2005) are assumed as an easy, safe, proper and cheap method to determine the health of animals (Hansen et al 2008). Minerals have vital role in the efficiency of growth, production and reproduction performances. The major duties of Cu and Fe in hematopoiesis and Zn in body tissues health, which means that the health status is directly influenced by the mentioned minerals. Different studies in many aspects of minerals activity and their interrelationships have already been carried out in ruminants though not completely in equines (Radostits et al 2007). Variation and diagnosis of the trace minerals is complex and their blood values are considered as the pathological criteria. Thus, the assessment of the blood mineral concentrations in physiological status assumes the diagnostic criteria in horses of the different geographical areas. The interactions between minerals reveal different aspects on physiological aspects or pathological status (Yousef et al 2012) such as direct correlations between Cu/Fe in hematopoiesis and reverse correlation between Cu/Mo (Blanco et al 2006). Study on the relationships among minerals in horses is not abundant and requires further investigation. The aims are to determine and comparison of the serum mineral concentrations in Urmia equines and mules and finally, the relationships among minerals in equines.
Material and Ten ml blood was collected randomly from 100 horses and mules in 2013. Horses belonged to kurd breed and mules were local indigenous. Sera were separated for mineral analysis. Overall, equines were 78 horses and 22 mules, 43 stallions and 57 mares. Age frequency was 1-6, 7-12 and 13-21 years old (Table 1). Animals were fed forages, dry and wet alfalfa in closed pens or pasture. They did not receive salt, minerals and electrolyte supplementation. Horses were not pregnant, foaled or in lactation period. Serum Cu, Fe and Zn were measured by atomic absorption spectrometry machine using Cu, Fe and Zn in mg/dl. Mean minerals were compared by ANOVA and t-test to determine the species, gender and age variations. Correlations were run to determine the relationships among minerals.
The overall mean serum trace-mineral concentrations were 14.5, 40.2 and 7.48 μg/dl, respectively (Table 2). Serum Cu was normal and consistent with Kavazis et al (2002), but greater than Biricik et al’s (2005) report. The role of Cu in horses is about 7 times less than in cows and important in hematopoiesis and milk yield (Laven et al 2007). Low Cu is responsible cause for anoestrus in mares (Farah et al 2013). Serum Fe concentration in equines was less than that reported by Radostits et al (2007) but higher than Sema et al’s (2010) findings, meaning that Fe deficiency is exists in Urmia equines. The role of Fe in hematopoiesis (Laven et al 2007), health status and milk production is important (Hansen et al 2008). One of the reasons for low Fe in the Urmia equines is perhaps the mineral competition in food and lack of concentrate feeding as mentioned by Farah et al (2013) in pregnant and non pregnant mares. The amount of serum Zn was consistent with Kavazis et al (2002), less than Murase et al (2013) and higher than Massanyi et al’s (2014) findings. No Serum Zn deficiency was expected in Urmia equines. The world findings show low serum Zn in equines which is possibly due to the seasonal variation in Zn food (Biricik and Ocal 2005), mineral competition and lack of concentrate feeding (Norouzi et al 2013). The amounts of minerals in mules were non significantly higher than in horses, which means that species did not affect on mineral values (Murase et al 2013 and Sema et al’s 2010). The age of animals had also no influence on mineral levels but the ages 11 to 14 years old could be critical in trace mineral reduction in horses (Okumura et al’s 1998). Age variations in serum Cu and Fe in Urmia equines was greater than in Zn and indicates that these animals are probably more susceptible to trace mineral deficiency. Trace mineral concentrations vary during the equine diseases. In respiratory disease Fe and Zn reduce but Cu increases, Zn declines following shipping fever, babesiosis and cellulitis (Yousef et al 2012). In babesiosis Fe and Cu increase while in equine herpes virus 1, Cu and Zn reduce and Fe increases (Yörük et al 2007). For this reason serum Zn is assumed as an index in inflammatory diseases in equines (Murase et al 2013). This suggests that during the treatment procedure of diseases Zn supplementation must be considered. None of these disorders were included in the horses and mules of this study. The main advantage of the study was to determine the relationships among minerals and to identify the premier indices existing in the blood of horses which have not been reported before. The interrelationships among minerals in blood, tissues, bones, muscles, urine and CSF require further investigation in horses. The correlations between minerals demonstrate an optimal coordination or contrast among minerals. Similar results have been reported by Bigras and Tremblay (1998) in cows, but not in horses (Massanyi et al 2014). Among minerals, the role of Cu, Fe and Zn are vital in animal survival. The presence of the strong relationship of Zn with Cu and Fe showed that Zn probably be considered as the most important index in equine health (Murase et al 2013).
Trace minerals in Urmia equines were at the normal range, and were not influenced by spices, gender and age parameters, except for serum iron which was low in females and the ages of 14 years old could be considered as probable trace mineral deficiency in horses. The correlations among minerals reveal their close corporations in the equine body. Therefore, Urmia equines did not suffer copper, iron and zinc deficiency, although mares at 14 years old probably susceptible to iron deficit.

BAKGROUND: Age and season may affect the thyroid gland, which regulates the metabolism of the body.
The experiment was conducted to study the effects of age and season on the concentration of thyroid hormones T3, T4, T3uptake, T3/T4 and free thyroxin index (FTI).
Blood samples were collected from jugular vein of 21 healthy purebred Arabian male horse in summer (July) and winter (January). The male horses were under the same management and feeding program in three age groups 2-6, 6-10 and 10-14 years. After centrifugation of blood samples and isolation of serum, the concentration of thyroid hormones were measured in serum by standard radio immunoassay (RIA) method.
Results showed that there is significant differences in mean values of serum T4, T3uptake and T4/T3 ratio between summer and winter seasons (P>0.05). The concentration of T3 and free thyroxin index (FTI) did not show a statistically significant differences between summer and winter (P>0.05). In summer, the concentration of T4 and FTI value in 2 to 6 years and the ratio of T4 to T3 in 10 to 14 years old males had significantly differences than other ages (P>0.05). In winter, there were not significantly differences for thyroid parameters among various ages of males (P>0.05).
The results of this study showed that under constant conditions, thyroid gland performance may be affected by season and ages in Arabic male horses.

In order to study the effects of age and season on concentration of the blood serum testosterone and the scrotum circumference, blood samples were taken, in summer (July) and winter (January) from jugular vein of 21 purebred Arabian stallions categorized in 2-6, 6-10 and 10-14 years of age. The concentration of the blood testosterone and the size of scrotum circumference were measured by the standard radioimmunoassay and collis vernier, respectively. Comparison of subjected parameters between summer and winter seasons were conducted using t-test and the differences among the three age groups in two seasons were done by one-way ANOVA, fitting Duncan test as implemented in the SPSS software. Results showed that there were not significant differences in blood serum testosterone concentrations between summer and winter seasons (P>0.05). The average size of the scrotum circumference in the summer season was significantly greater than that observed in winter (P<0.05). In the winter, the average testosterone concentration in the stallions of 10 to 14 years of age was significantly greater than 6 to 10 years-old stallions (P<0.05), but in the summer, the average concentration of testosterone did not varied significantly between age groups (P>0.05). Also, the size of scrotum circumference in three studied age groups was not significantly varied between two seasons (P>0.05). The results showed the increasing levels of testicular volume and testosterone in the summer that is evidence of increased reproductive activity, But don’t observed the increase or decrease in the mean testosterone level and scrotum circumference in 3 age 2 to 6, 6 to 10 and 10 to 14 years in both seasons.

The objective of this study was to investigate the effect of age، sex on thyroid’s hormones levels and rhythmicity of these hormones in turkey chickens. 20 turkey chickens were randomly assigned to two groups (male=10&female=10). Blood samples were collected at 10 d intervals during 80 days. Data were analyzed with Proc Mixed of SAS. In second experiment، circadian rhythmicity of thyroid hormone in male and female was studied. 16 turkey chickens (male=8&female=8) were randomly selected and blood samples were collected at 2 hours intervals for 24 hours. Then، the plasma concentration of thyroid’s hormones were measured. Results showed that the effect of age on plasma concentration of thyroxin was significant but there was not significant different between male and female birds. By aging the birds، concentration of thyroxin enhanced. Plasma concentration of thyroxin in female and male was 20. 63±1. 6 vs. 20. 58±1. 7 µg/dl، respectively. Effect of genus and age on plasma concentration of triiodothyronine was significant. Overall mean plasma concentration of triiodothyronine in female chicken (209. 72±0. 34 ng/ml) was higher than male chicken (187. 74±0. 30 ng/ml). Possitive correlation was indicated between age and triiodothyronine level in male birds، while negative correlation was detected in female birds. Results of second experiment showed thyroxin increased during the night and decreased during the daytime، while the mean plasma concentration of triiodothyronine increased during the daytime and decreased during the night.

Hair samples، obtained from 56 dromedary camel (aged <1 to 12 years of age) in Khorasan province، were examined. Analysis of variance indicated a significant (P<0. 05) effect of sex on interrupted medullated، non medullated fibers، shoulder and hump staple length، and also on coefficient variation of mean down fiber diameter. There was significant different (P<0. 01) on interrupted medullated fibers and non medullated fibers of inner coat and shoulder، flank and hump staple length between young camel and other females of different age groups. The range of inner coat was 69. 4 and 96 percent that related to aged and adult groups in females respectively. The young and adult female camels have minimum and maximum of 15. 6 and 31. 16 μm mean down fiber diameter respectively.