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Articles by G. Rahimi
Total Records ( 9 ) for G. Rahimi
  S. Zakizadeh , G. Rahimi , S.R. Mirae-Ashtiani , A. Nejati-Javaremi , M. Moradi-Shahrbabak , P. Reinecke , M. Reissmann , A.A. Masoudi , C. Amirinia and S.A. Mirhadi
  The aim of this study was to estimate the allelic frequency in polymorphic sites of intron 3 and exon 5 of bovine growth hormone gene in three Iranian native and Holstein cattle. A total of 406 genomic DNA samples were extracted from three Iranian native cattle including, Mazandarani 97, Sarabi 87, Golpaygani 112 and Holstein 110 cattle. The PCR procedure was used to amplify 345 bp of bGH-intron 3 and 404 bp of bGH-exon 5. The frequencies of MspI (+) allele were estimated as 0.55, 0.51, 0.44 and 0.83 in Mazandarani, Sarabi, Golpaygani and Holstein breed, respectively. The allelic frequencies of AluI (+) were calculated as 0.91, 0.84, 0.92, 0.85 and for DdeI (+), 0.52, 0.54, 0.47 and 0.86, for these breeds, respectively. Chi-square test showed significant differences (p<0.01) in genotypic frequency between native and Holstein breed in MspI and DdeI restriction sites. There was significant differences in genotypic frequencies between Mazandarani (p<0.05) and Golpaygani (p<0.01) with Holstein breed at AluI restriction site. This difference was not significant between Sarabi and Holstein breed. The differences in allelic frequency between native breeds and Holstein cattle at the present study might be due to differences in origin of breeds, selection plans applied to Holstein population for improving milk production.
  G. Rahimi , M. Rezaei , H. Hafezian and H. Saiyahzadeh
  In an experiment with complete randomized design, the effect of intermittent lighting (1 h L: 3 h D) was studied on performance of 400 broiler chicks from 10 to 42 d of age. During of the experiment feed intake, body weight, feed conversion ratio were measured weekly. Mortality was measured throughout the experiment. At 42 d of age 10 chicks from each treatment were slaughtered for abdominal fat weight. There wasn`t significant difference for body weight at 42 d between treatments. Use of intermittent lighting schedule improved feed conversion ratio significantly (P<0.05). Due to decrease fat deposition, intermittent lighting program reduced abdominal fat percentage (P<0.05). There wasn`t significant difference between treatments for mortality. In conclusion, since physical activity is very low during darkness, and energy expenditure for activity is reduced, therefore use of intermittent lighting program enhanced production efficiency, reduced room temperature and cost of electricity.
  G. Rahimi
  The aim of this study was to figure out the response of the GH axis to selection criteria in broiler chickens. Plasma profiles of GH, IGF-I along with membrane GHR binding activity were examined during rapid growth phase in experimental lines of broiler chickens. The selection criteria applied influenced the plasma GH levels and the number of hepatic GHR. There was a higher plasma GH level in FC chickens compared to GL chickens while the opposite pattern was observed for GHR. The negative correlation between plasma GH levels and hepatic GHR suggest a down regulatory mechanism for GHR in broiler chickens. The absence of line differences in plasma IGF-I levels between GL and FC lines in spite of clear difference in growth rate and in plasma GH concentrations may support the concept that plasma IGF-I does not appear to be GH-dependent, implying the importance of other factors besides GH in the regulation of IGF-I in chickens. The slower growth rate as function of time in the FC line during rapid growth phase was followed by a phase of compensatory growth. On the basis of this growth curve pattern it can be hypothesized that the dynamics of GH action are shifted or extended to the phase of compensatory growth as an effect of the selection on feed conversion. This may be a causal mechanism for the different growth curve pattern in GL and FC lines. Assuming that the metabolic basis for these differences is better understood it may be possible to device other procedures for improving meat quality in poultry industry.
  G. Rahimi
  The present study was carried out to investigate the influence of genotypes on endocrine parameters in broiler chickens selected for fast growth or better feed conversion rate during the early growth phase. The thyroid hormones levels, hepatic deiodinase enzymes and thyroid hormone receptor activity were analyzed in plasma and hepatic cells of broiler chickens. Age-related changes in plasma T4 and T3 levels were observed. The decrease of plasma T3 levels as a function of age was correlated with relative growth rate. The positive relation between T3 levels and relative growth rate supports the idea that the greater synthesis of this anabolic hormone may be required for the increase in efficiency of protein deposition in chickens at younger ages. In contrast to plasma T3 concentrations, plasma T4 levels increased gradually with age. Analysis of the T3 concentration showed a tendency for higher plasma T3 levels at week 4 and significantly higher at week 7 on the GL compared to the FC line. The plasma T4 concentration in growth selected line was higher in general, and statistically significant at week 4 and 7 of age. The present data show that the decrease of T3 as a function of age is associated with a decrease in type I deiodinase activity. Analysis of deiodinase enzymes showed a non-significantly higher type I deiodinase activity in the fast growing than in the slow growing line at week 4 and 7 of age. A significant age differences were found in type I deiodinase activity within the GL line with lower hepatic type I deiodnase activity at week 7 compared to week 4. No line differences were found in specific binding activity, binding capacity and binding affinity constant between lines, which may indicate that the receptor configuration does not differ among the lines. With this finding, it may be concluded that the hepatic T3-receptor characteristics have not been influenced by the selection criteria that has been used to create these divergent lines.
  G. Rahimi
  The present study was carried out to investigate the effect of different heat shock programs at early growth phase on glucose and calcium regulating axis in broiler chickens. The Comparison of body weight gain between different experimental groups showed that relative growth rate was significantly reduced in heat shock treated groups at fist week of age. After this period, the heat exposed groups gradually showed a compensatory growth and at the end of starter period the relative growth rate was significantly higher in heat shock treated groups compared to control group. The exposure of heat shock at the beginning of rearing period (day 3-6) and at the end of rearing period (day 42) has significantly increased plasma calcium levels. After the heat shock period, no differences in plasma calcium concentrations was found. The plasma glucose level was significantly reduced during temperature conditioning in heat shock treated groups compared with control group. After heat shock conditioning, plasma glucose levels returned to normal situation indicating that no differences in plasma glucose concentrations could be detected. There were no differences in plasma triglycerids concentrations between experimental groups. The results indicate that the glucose and calcium metabolism axes is one of the most important target in pre-heat shock conditioning to reduce mortality in broilers raising. Probably, the exposure of heat shock at early growth phase in broiler chickens can improve the bird`s thermotolerance ability to heat shock at higher ages by rapid response of birds to provide glucose via stored resources. In conclusion, exposure of heat shock at early growth phase in spite of improved bird`s final performance and survival ability during acute heat shock at later ages, can be used as a suitable model to understand the biological phenomenon related to the mechanisms of thermoregulation.
  G. Rahimi
  In recent years, the consumer`s desire for healthier foods has increased the demand for animal products containing low cholesterol and enriched with omega-3 fatty acids. In response to the perceived need, poultry researchers have focused on reducing egg yolk cholesterol to satisfy the health conscious of consumers. The present study was conducted to determine the effects of dietary forage legume supplementation on plasma triglyceride and cholesterol concentrations, egg yolk cholesterol contents and egg shell characteristics in indigenous laying hens at Mazandaran Native Fowls Breeding Station in north of Iran. A total of 60 laying hens were kept under commercial conditions from 35-45 weeks of age and were fed a commercial isocaloric and isonitrogenous corn-soybean meal diet. Birds were divided randomly into six treatment groups of ten birds each, and fed diets containing 0, 0.75, 1.25, 2.5, 5 and 10% added forage legume for 10 weeks. Ten eggs from each treatment groups were pooled in the last four-day of each period for the egg yolk cholesterol contents and egg shell breaking strength. The blood samples were taken from the wing-vein at the end of each period from all birds of each treatment groups for serum triglyceride and cholesterol contents. The results showed that there were no significant differences in final body weight, egg weight and yolk weight due to different forage legume treatments. Forage legume supplementation to the diet did not significantly affect plasma cholesterol and triglyceride concentration, while it has significantly (p<0.05) reduced egg yolk cholesterol concentrations. Egg yolk cholesterol content was reduced from 16.41mg/g yolk in control group to 13.01mg/g yolk in 10% forage legume supplemented diet. Feeding the basal diet supplemented with any of 0, 0.75, 1.25, 2.5, 5 and 10% levels of forage legume had no significant effect on egg breaking strength. The results demonstrate that there is no co-linearity response on plasma cholesterol level and egg yolk cholesterol content to the dietary forage legume supplementation. It can be concluded that the incorporation of forage legume supplementation in layer diets could improve egg quality with no any negative effects on laying hen`s performance.
  B. Navidshad , M. Shivazad , A. Zare Shahneh and G. Rahimi
  This experiment carried out to study the effects of dietary fat saturation on performance and serum thyroid hormones of broilers under free or skip a day nutrition at 18-28 days of age. We used 720 male Ross 308 broiler chickens in a completely randomized design with a 2*4 factorial arrangement with 3 replicate and 30 chicks for each replicate. Experiment factors were: 1- skip a day or free feeding at days 10-28 of age and, 2- diets with different unsaturated to saturated fatty acid ratios (2, 3.5, 5 and 6.5) formulated using different levels of sunflower oil and tallow. At 28 and 42 days of age, weight gain and feed consumption recorded and blood samples were taken. SAS software used for Variance analysis and means comparing. Skip a day nutrition at days 18-28 of age significantly reduced feed intake and weight gain and increased feed conversion, But free nutrition at days 29-42 of age removed this differences. At day 28, diet with unsaturated to saturated ratio of 6.5 significantly reduced feed intake and weight gain and increased feed conversion. At day 42 of age dietary fat type didn`t have any significant effect on feed intake and weight gain but altered feed conversion as a manner same to day 28 of age. Skip a day nutrition significantly decreased T3 and increased T4 levels at day 28 of age but this effects were disappeared after re-feeding at day 42 of age. This survey showed that feed restriction didn`t affect bird`s ability to utilize fats with different degrees of saturation. Fat type and feed restriction affect broilers performance separately without any interaction. Dietary fat saturation didn`t have any significant effect on serum thyroid hormones levels, while feed restriction have a pronounce effect.
  Z. Daliri , S.H. Hafezian , A. Shad Parvar and G. Rahimi
  The aim of this study was to explore the impact of production and type traits on the functional herd life of Iranian Holstein cows using multiple regression models. The data set consisted of 896,834 registered cows from 2005 herds calving from 1971-2003. The obtained records from these cows used to estimate the correlation coefficients between THL and FHL traits using milk production and 19 linear type traits. The data set related to registered Holstein cows were provided by NABC of Iran. Parameters were estimated using univariable animal model with the restricted maximum Likelihood method. Heritability and Breeding Value were estimated using univariable analysis for milk, fat and protein yield during 305 days. Heritability for these traits was calculated 0.25, 0.23 and 0.19, respectively. The Heritability values for THL and FHL ranged from 0.04-0.03, respectively. Among type traits, teat length had the lowest (0.007) and rear teat placement had the highest heritability (0.50) values. Phenotypic correlation between FHL and stature, body depth, rump width and udder characteristics was negative, which indicates the cows with smaller body, shorter stature have longer productive life. The phenotypic correlation between FHL and feet angularity, mammary ligaments, teat length and production traits (milk and fat yield) were positive. Feet and legs along with mammary system also had a strong relationship with functional longevity. Among the linear type traits, udder traits such as teat height and rear udder width were the most important, with a strong relationship with functional herd life of cows. The type traits of stature, size and rear udder height showed the lowest relationship with functional longevity. The obtained results at the present study shoed that the improvement of production along with type traits either through genetics or management would have a positive influence on the functional longevity of cows.
  H. Sayyazadeh , G. Rahimi and M. Rezaei
  The use of enzymes has been common in many industries for many years. More recently, the animal feed industry began to incorporate specific enzymes in the animal and poultry feed. The main goals of enzyme supplementation of poultry diets have predominantly been related to the hydrolysis of fiber or NSP fraction in cereal grains. The purpose of the present study was to investigate the effect of exogenous enzyme supplementation of maize, wheat and barley-based diets on broiler performance. A total of 720 one day-old broiler chicks (Arian breed) were allotted at random in equal numbers in floor pens (3 pen/treatment) and fed with 8 different ingredient diets. Broiler diets were prepared based on: a standard maize based diet (M); maize plus enzyme (ME); barley plus enzyme (BE); wheat plus enzyme (WE); maize-barley plus enzyme (MBE); maize-wheat plus enzyme (MWE); wheat-barley plus enzyme (WBE) and maize-wheat-barley plus enzyme (MWBE). From day 7 onwards and repeated weekly body weight gain, feed intake, feed conversion, mortality was determined. At the end of rearing period six chickens per treatment were slaughtered and carcass yield, abdominal fat pad content, intestine`s weight and size changes were measured. The result gives an impression that no significant differences were found in terms of live weight, feed intake, feed efficiency and chick`s survivability between enzymes treated and control diets. Dietary enzymes had no effect on gizzard and liver weight, carcass yield and abdominal fat pad contents. Enzyme supplementation, however significantly influence the weight but not the size of intestine. It has been shown that adding of enzyme to the feeds based on cereal grains with higher fiber contents improve the performance of broiler chicks to the levels at least as those obtained with maize based diets. The obtained results at the present study indicate the anti-nutritive effects of SNP on the performance of broilers were overcome by adding of enzymes.
 
 
 
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