پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effects of different strategies for selection of animals as reference population on the accuracy of genomic evaluation for moderate heritability traits in dairy cattle Effects of different strategies for selection of animals as reference population on the accuracy of genomic evaluation for moderate heritability traits in dairy cattle 1 9 62041 10.22059/ijas.2017.118008.653285 FA Azade Boustan Assistant Professor, Department of Animal Science, Moghan College of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Iran Elham Rezvannejad Assistant Professor, Department of Biotechnology, Institute of Science and High Technology and Environmental Science, Graduate University of Advanced Technology, Kerman, Iran Ardeshir Nejati Javaremi Associate Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Reza Seyedsharifi Assistant Professor, Department of Animal Science, Faculty of Agriculture Science and Natural Resources, University of Mohaghegh Ardabili, Iran Journal Article 2015 02 10 An important question about genomic evaluation is the effectiveness of using superior animals as reference population, on the accuracy of estimated breeding values of selection candidates. In this research, the accuracy of genomic evaluation is selecting superior animals as reference population (strategy1) was compared to situations in which the animals in reference population were a random sample of population (strategy2) and superior and inferior animals (strategy3). Best linear unbiased prediction method was used to estimate marker effects. The results showed that using only superior animals as reference population would decrease the accuracy of genomic evaluation. If the ratio of animals in the reference group is low (for example 10%) the difference between strategy1 and the other strategies would be more than the situation in which this ratio is high (for example 50%). For example in situation that the generation before validation set (generation four) was used as reference population, the accuracy of strategy1 was about 0.34 lower than strategy3 when 10% of animals were used as reference population but this difference was decreased to 0.04 when 50% of animals were used as reference population. These results showed that genotyping and using some of no superior animals in the reference population, beside to superior animals with high accurate traditional estimated breeding values, could lead to increase in the accuracy of genomic evaluation. An important question about genomic evaluation is the effectiveness of using superior animals as reference population, on the accuracy of estimated breeding values of selection candidates. In this research, the accuracy of genomic evaluation is selecting superior animals as reference population (strategy1) was compared to situations in which the animals in reference population were a random sample of population (strategy2) and superior and inferior animals (strategy3). Best linear unbiased prediction method was used to estimate marker effects. The results showed that using only superior animals as reference population would decrease the accuracy of genomic evaluation. If the ratio of animals in the reference group is low (for example 10%) the difference between strategy1 and the other strategies would be more than the situation in which this ratio is high (for example 50%). For example in situation that the generation before validation set (generation four) was used as reference population, the accuracy of strategy1 was about 0.34 lower than strategy3 when 10% of animals were used as reference population but this difference was decreased to 0.04 when 50% of animals were used as reference population. These results showed that genotyping and using some of no superior animals in the reference population, beside to superior animals with high accurate traditional estimated breeding values, could lead to increase in the accuracy of genomic evaluation. https://ijas.ut.ac.ir/article_62041_7eeace5fbef2ac26cfa58b1b6aa8f9af.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 The pattern of linkage disequilibrium in three native Iranian sheep breeds The pattern of linkage disequilibrium in three native Iranian sheep breeds 11 18 62042 10.22059/ijas.2017.221876.653485 FA Somayeh Barani M. Sc. Student, Professor, Department of Animal Science, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Mohammad Moradi-Shahrbabak Professor, Department of Animal Science, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0002-5255-609X Ardeshir Nejati-Javaremi Associate Professor, Department of Animal Science, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Mohammad Hosein Moradi Assistant Professor, Department of Animal Science, University of Arak, Iran Mohsen Gholizadeh Assistant Professor, Department of Animal Science, University of Sari, Iran Majid Khansefid Assistant Professor, Department of Animal Science, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Journal Article 2016 12 04 Understanding the pattern of linkage disequilibrium (LD) in different populations provides useful information for genomic selection (GS), genome wide association studies (GWAS) and identification of genetic architecture of traits by estimating the persistence of LD phase between markers and quantitative trait loci (QTL). The aim of this research was to estimate of the extent of LD in three Iranian native sheep breeds. Therefore, 186 blood samples were taken from three sheep breeds (96 Baluchi, 45 lori-Bakhtiari and 45 Zel) and genotyped by Illumina ovine 50K SNPChip, then linkage disequilibrium in any breed were measured using r². The results showed that the highest average values of r² at inter marker distance of less than 10Kb were 0.392± 0.323, 0.360±0.308 and 0.340±0.306 in Baluchi, Lori-Bakhtiari and Zel, respectively. The highest average values of r² in autosome chromosomes of each breed were obtained for chromosome 24 and 25 in Baluchi, 9 and 21 in Lori-Bakhtiari and 23 and 24 in Zel. The amount of LD reduced with increasing the distance between markers, the extent of LD was less than 0.1 at inter marker distances greater than 100Kb. The comparison of correlation coefficients LD between different breeds showed a strong persistence of LD phase between Zel and Lori-Bakhtiari breeds which is probably due to recent common ancestors between these two breeds.  Generally, with increase amount of LD means that lower marker density in association studies will be required. The results of this study showed to achieve genomic prediction accuracy of 85%  (assuming there is no other accuracy limiting factor) and robust GWAS results, the density of markers must be higher than 50K SNPChip. Understanding the pattern of linkage disequilibrium (LD) in different populations provides useful information for genomic selection (GS), genome wide association studies (GWAS) and identification of genetic architecture of traits by estimating the persistence of LD phase between markers and quantitative trait loci (QTL). The aim of this research was to estimate of the extent of LD in three Iranian native sheep breeds. Therefore, 186 blood samples were taken from three sheep breeds (96 Baluchi, 45 lori-Bakhtiari and 45 Zel) and genotyped by Illumina ovine 50K SNPChip, then linkage disequilibrium in any breed were measured using r². The results showed that the highest average values of r² at inter marker distance of less than 10Kb were 0.392± 0.323, 0.360±0.308 and 0.340±0.306 in Baluchi, Lori-Bakhtiari and Zel, respectively. The highest average values of r² in autosome chromosomes of each breed were obtained for chromosome 24 and 25 in Baluchi, 9 and 21 in Lori-Bakhtiari and 23 and 24 in Zel. The amount of LD reduced with increasing the distance between markers, the extent of LD was less than 0.1 at inter marker distances greater than 100Kb. The comparison of correlation coefficients LD between different breeds showed a strong persistence of LD phase between Zel and Lori-Bakhtiari breeds which is probably due to recent common ancestors between these two breeds.  Generally, with increase amount of LD means that lower marker density in association studies will be required. The results of this study showed to achieve genomic prediction accuracy of 85%  (assuming there is no other accuracy limiting factor) and robust GWAS results, the density of markers must be higher than 50K SNPChip. https://ijas.ut.ac.ir/article_62042_4e595a9dc2191a4e4e0c929ebf2c15d9.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effects of dietary anion-cation balance during starter period on performance, small intestine morphology, serum electrolyte level, and tibial mineralization in broiler chicks Effects of dietary anion-cation balance during starter period on performance, small intestine morphology, serum electrolyte level, and tibial mineralization in broiler chicks 19 28 62044 10.22059/ijas.2017.216280.653470 FA Sohaila Azarzartosht Former M. Sc. Student, Animal Science Department, University of Kurdistan, Sanandaj, 66177-15175, Kurdistan, Iran Ahmad Karimi Associate Professor, Animal Science Department, University of Kurdistan, Sanandaj, 66177-15175, Kurdistan, Iran Gorbanali Sadeghi Professor, Animal Science Department, University of Kurdistan, Sanandaj, 66177-15175, Kurdistan, Iran Journal Article 2016 09 28 This experiment was carried out to investigate the effects of starter period’s (1 to 10 d) dietary cation-anion balance on performance, tibia bone mineralization, serum electrolyte level, carcass characteristics and small intestine morphology. A total of 280 day-old broiler chicks of Ross 308 strain were used in a completely randomized design. Treatments consisted of five different level of dietary cation-anion balance (150, 200, 250, 300, and 350 mEq/Kg) and each of them replicated four times (14 birds per replicate). The results showed that feeding a diet with anion-cation balance of 350 mEq/Kg, significantly (P<0.05) reduced body weight and weight gain during starter and grower periods, feed intake reduced and feed conversion ratio increased during starter period. Dietary cation-anion balance had no significant effects on serum electrolytes, relative weight of carcass and gastrointestinal organs to body weight and intestinal morphology. Reducing dietary cation-anion balance level to less than 300 mEq/Kg had no significant (P>0.05) effects on tibia bone ash content, but significantly (P<0.05) reduced the phosphorus and calcium content of tibia ash at 21 and 42 days of age, respectively. In conclusion, the results indicated that maintaining appropriate dietary cation-anion balance during starter period (200 to 300 mEq/kg) is utmost important to achieve optimal broiler chicks’ performance. This experiment was carried out to investigate the effects of starter period’s (1 to 10 d) dietary cation-anion balance on performance, tibia bone mineralization, serum electrolyte level, carcass characteristics and small intestine morphology. A total of 280 day-old broiler chicks of Ross 308 strain were used in a completely randomized design. Treatments consisted of five different level of dietary cation-anion balance (150, 200, 250, 300, and 350 mEq/Kg) and each of them replicated four times (14 birds per replicate). The results showed that feeding a diet with anion-cation balance of 350 mEq/Kg, significantly (P<0.05) reduced body weight and weight gain during starter and grower periods, feed intake reduced and feed conversion ratio increased during starter period. Dietary cation-anion balance had no significant effects on serum electrolytes, relative weight of carcass and gastrointestinal organs to body weight and intestinal morphology. Reducing dietary cation-anion balance level to less than 300 mEq/Kg had no significant (P>0.05) effects on tibia bone ash content, but significantly (P<0.05) reduced the phosphorus and calcium content of tibia ash at 21 and 42 days of age, respectively. In conclusion, the results indicated that maintaining appropriate dietary cation-anion balance during starter period (200 to 300 mEq/kg) is utmost important to achieve optimal broiler chicks’ performance. https://ijas.ut.ac.ir/article_62044_d685688c3c719636baea21bae4a26262.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 The effect of different sources of Fat supplement on growth performance, blood metabolites and ruminal parameters The effect of different sources of Fat supplement on growth performance, blood metabolites and ruminal parameters 29 37 62043 10.22059/ijas.2017.200496.653421 FA Shahpour Kheirabadi M.Sc. Student, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Mehdi Dehghan-banadaky Associate Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Mehdi Ganjkhanlou Associate Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Journal Article 2016 04 06 The aim of this study was to evaluate the effect of starch sources replacement by fat supplements on growth performance, rumen fermentation and blood metabolite parameters of Holstein young bulls. 28 Holstein young bulls (274±31 Kg BW) were fed with four diets containing 1) diet with high level of saturated fat supplement 2) diet with low level of saturated fat supplement 3) diet with high level of unsaturated fat supplement and 4) low level of unsaturated fat supplement for in completely randomized design duration about 100 days. Diets were formulated to be isoenergetic and isonitrogenous. Body weight changes and dry mater intake, were measured montly and daily repectively. Daily body weight gain, final weight, DMI and feed conversation rate were not different between treatments. Individual volatile fatty acids concentration not affected by treatments. Blood metabolite parameter were measured and there was no significant effect observed between treatments except for total cholesterol which in diets with high level of crude fat (6.9%) was grater (p<0.05) than diets with low level of crude fat (3.8%). Finally, based on the results, it can be concluded that fatty acids supplements can be used as an energy source in feedlot farms in shortage of grain. The aim of this study was to evaluate the effect of starch sources replacement by fat supplements on growth performance, rumen fermentation and blood metabolite parameters of Holstein young bulls. 28 Holstein young bulls (274±31 Kg BW) were fed with four diets containing 1) diet with high level of saturated fat supplement 2) diet with low level of saturated fat supplement 3) diet with high level of unsaturated fat supplement and 4) low level of unsaturated fat supplement for in completely randomized design duration about 100 days. Diets were formulated to be isoenergetic and isonitrogenous. Body weight changes and dry mater intake, were measured montly and daily repectively. Daily body weight gain, final weight, DMI and feed conversation rate were not different between treatments. Individual volatile fatty acids concentration not affected by treatments. Blood metabolite parameter were measured and there was no significant effect observed between treatments except for total cholesterol which in diets with high level of crude fat (6.9%) was grater (p<0.05) than diets with low level of crude fat (3.8%). Finally, based on the results, it can be concluded that fatty acids supplements can be used as an energy source in feedlot farms in shortage of grain. https://ijas.ut.ac.ir/article_62043_71eb716c9ea60886892dc716ce11aa9c.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Genome-wide evaluation of effective population size in some Iranian sheep breeds using linkage disequilibrium information Genome-wide evaluation of effective population size in some Iranian sheep breeds using linkage disequilibrium information 39 49 62045 10.22059/ijas.2017.213736.653464 FA Mohammad Hossein Moradi Assistant Professor, Department of Animal Science, Faculty of Agriculture and Natural Resources, Arak University, Arak 38156-8-8349, Iran Amir Hossein Farahani Assistant Professor, Department of Animal Science, Faculty of Agriculture and Natural Resources, Arak University, Arak 38156-8-8349, Iran Ardeshir Nejati-Javaremi Associate Professor, Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Iran Journal Article 2016 08 21 The aim of the present study was to estimate the effective population size (Ne) in some Iranian sheep breeds using genome wide SNP data. A total of 217 animal samples consisting of 45, 37, 34, 35, 45 and 11 samples from Zel, Afshari, Moghani, Qezel, Lori-Bakhtiari and a wild-type of Iranian sheep breeds, genotyped by Illumina OvineSNP50K Beadchip assay were used in this study respectively. This study has been performed in collaboration with the Ovine HapMap project. The Ne was estimated using linkage disequilibrium across 4 up to 3500 generations ago. The result of principal component analysis (PCA) indicated that all breeds will be separated from each other in the first two principal components. Average expected and observed heterozygosity for different breeds ranged 0.36-0.37 and 0.37-0.43 respectively. The Ne results showed a decreasing trend over the last 3500 generations for all breeds, with an increasingly slope since about last 550 generations. The Ne in Iranian sheep breeds for 4 generations ago were ranged from 9 up to 89. The highest historically effective population size was found for Zel breed (89 heads) and the lowest for Afshari (44 heads) and wild_type (9 heads) sheep breeds. Generally, the results indicated that although a considerable genetic variation exists in these populations, however Ne has been decreased strongly in Iranian sheep breeds especially in Afshari and wild-type sheep breeds during recent years and designing of appropriate programs is necessary to conserve remaining purebred animals of these indigenous sheep breeds.  The aim of the present study was to estimate the effective population size (Ne) in some Iranian sheep breeds using genome wide SNP data. A total of 217 animal samples consisting of 45, 37, 34, 35, 45 and 11 samples from Zel, Afshari, Moghani, Qezel, Lori-Bakhtiari and a wild-type of Iranian sheep breeds, genotyped by Illumina OvineSNP50K Beadchip assay were used in this study respectively. This study has been performed in collaboration with the Ovine HapMap project. The Ne was estimated using linkage disequilibrium across 4 up to 3500 generations ago. The result of principal component analysis (PCA) indicated that all breeds will be separated from each other in the first two principal components. Average expected and observed heterozygosity for different breeds ranged 0.36-0.37 and 0.37-0.43 respectively. The Ne results showed a decreasing trend over the last 3500 generations for all breeds, with an increasingly slope since about last 550 generations. The Ne in Iranian sheep breeds for 4 generations ago were ranged from 9 up to 89. The highest historically effective population size was found for Zel breed (89 heads) and the lowest for Afshari (44 heads) and wild_type (9 heads) sheep breeds. Generally, the results indicated that although a considerable genetic variation exists in these populations, however Ne has been decreased strongly in Iranian sheep breeds especially in Afshari and wild-type sheep breeds during recent years and designing of appropriate programs is necessary to conserve remaining purebred animals of these indigenous sheep breeds.  https://ijas.ut.ac.ir/article_62045_32be821025b5459bada6ca0fb05c703e.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Storage of rooster semen in liquid form using alcoholic extract of rosemary Storage of rooster semen in liquid form using alcoholic extract of rosemary 51 59 62046 10.22059/ijas.2017.221168.653480 FA Haniyeh Ramezaninejad Former M. Sc. Student, Department of Animal Science, Faculty of Agriculture, University of Guilan, Iran Mohammad Roostaei Ali Mehr Associate Professor, Department of Animal Science, Faculty of Agriculture, University of Guilan, Iran 0000-0001-7578-467X Journal Article 2016 12 05 Current experiment was conducted to evaluate the effect of alcoholic extract of rosemary leaves on rooster sperm storage at 4 °C by using eight mature roosters. Semen collection was performed three days’ interval in 5 times. In each session, ejaculates were pooled, split into six parts and the amounts of 0 (R0), 10(R10), 20 (R20), 30 (R30), 40 (R40) and 50 µg/mL (R50) of rosemary extract were added to each part. After that, samples were chilled to 4 ℃ and kept until 72 h. Sperm viability (by staining Hoechst 33258), motility and functional membrane integrity were evaluated at 0 (T0), 24 (T24), 48 (T48) and 72 h (T72). Concentration of malondialdehyde (MDA) was determined to assay lipid peroxidation by one million spermatozoa at 48 h. The results showed that the concentration of MDA was lower in R50 (0.93 nM) than control (1.15 nM), but, it was higher than R40 (0.82 nM, P<0.05). Membrane integrity and sperm viability were higher in 40 µg/mL rosemary extract (75.72% and 73.56%, respectively) than control (70.6% and 69.08%, respectively) and 10 µg/mL extract (71.56% and 69.72%, respectively; P<0.05). There was interaction between rosemary extract and storage time on sperm motility (P<0.05). After 72 h, sperm motility was higher R40 (46%) than R0 (34%), R10 (35.6%) and R20 (38.8%, P<0.05). Therefore, rosemary extract improves quality of rooster spermatozoa during storage at 4 °C. Current experiment was conducted to evaluate the effect of alcoholic extract of rosemary leaves on rooster sperm storage at 4 °C by using eight mature roosters. Semen collection was performed three days’ interval in 5 times. In each session, ejaculates were pooled, split into six parts and the amounts of 0 (R0), 10(R10), 20 (R20), 30 (R30), 40 (R40) and 50 µg/mL (R50) of rosemary extract were added to each part. After that, samples were chilled to 4 ℃ and kept until 72 h. Sperm viability (by staining Hoechst 33258), motility and functional membrane integrity were evaluated at 0 (T0), 24 (T24), 48 (T48) and 72 h (T72). Concentration of malondialdehyde (MDA) was determined to assay lipid peroxidation by one million spermatozoa at 48 h. The results showed that the concentration of MDA was lower in R50 (0.93 nM) than control (1.15 nM), but, it was higher than R40 (0.82 nM, P<0.05). Membrane integrity and sperm viability were higher in 40 µg/mL rosemary extract (75.72% and 73.56%, respectively) than control (70.6% and 69.08%, respectively) and 10 µg/mL extract (71.56% and 69.72%, respectively; P<0.05). There was interaction between rosemary extract and storage time on sperm motility (P<0.05). After 72 h, sperm motility was higher R40 (46%) than R0 (34%), R10 (35.6%) and R20 (38.8%, P<0.05). Therefore, rosemary extract improves quality of rooster spermatozoa during storage at 4 °C. https://ijas.ut.ac.ir/article_62046_1b06b747d8195ee9363d3930f3eb93ae.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Estimate of genetic parameters of egg quality traits in Mazandaran native hens Estimate of genetic parameters of egg quality traits in Mazandaran native hens 61 67 62047 10.22059/ijas.2017.34200.653097 FA Homa Soleimani Former M. Sc. Student, Faculty of Agriculture, University of Zanjan, Iran Rasoul Vaez Torshizi Associate Professor, Tarbiat Modares University, Tehran, Iran Morad Pasha Eskandari Nasab Associate Professor, Faculty of Agriculture, University of Zanjan, Iran Seyed Reza Mirati Ashtiani Professor, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran 0000-0003-3597-4385 Mohammad Hossein Shahir Assistant Professor, Faculty of Agriculture, University of Zanjan, Iran Journal Article 2013 10 08 <span>A total of 37300 records of egg weight (EW) and 1540 records of egg quality traits, namely, albumen weight (AW), yolk weight (YW), egg shell weight (ESW), egg shell strength (ESS), egg shell thickness (EST) and haugh unit (HU) of Mazandaran native hens were used to estimate genetic and phenotypic parameters. Egg weight data collected during 1991 to 2006 and egg quality traits were measured in 3 consecutive days on 769 hens. Data were analyzed with restricted maximum likelihood procedure by using multiple-trait animal model. Estimates of heritabilities were 0.471, 0.747, 0.334, 0.595, 0.218, 0.465 and 0.536 for EW, AW, YW, ESW, ESS, EST and HU, respectively. The genetic correlation between HU and AW was positive and low (0.11), whereas it was negative and low with other egg quality traits. The EW had a positive and high genetic correlation with AW (0.95) and moderate with YW (0.45) and EST (0.39). The range of genetic correlations among all other traits varied from 0.04 (between AW and ESS) to 0.81 (between EST and ESS). These estimates for phenotypic correlations ranged from -0.13 (between YW and HU) to 0.95 (between EW and YW). These results indicated that selection based on EW may increase YW, AW and egg shell quality.</span> <span>A total of 37300 records of egg weight (EW) and 1540 records of egg quality traits, namely, albumen weight (AW), yolk weight (YW), egg shell weight (ESW), egg shell strength (ESS), egg shell thickness (EST) and haugh unit (HU) of Mazandaran native hens were used to estimate genetic and phenotypic parameters. Egg weight data collected during 1991 to 2006 and egg quality traits were measured in 3 consecutive days on 769 hens. Data were analyzed with restricted maximum likelihood procedure by using multiple-trait animal model. Estimates of heritabilities were 0.471, 0.747, 0.334, 0.595, 0.218, 0.465 and 0.536 for EW, AW, YW, ESW, ESS, EST and HU, respectively. The genetic correlation between HU and AW was positive and low (0.11), whereas it was negative and low with other egg quality traits. The EW had a positive and high genetic correlation with AW (0.95) and moderate with YW (0.45) and EST (0.39). The range of genetic correlations among all other traits varied from 0.04 (between AW and ESS) to 0.81 (between EST and ESS). These estimates for phenotypic correlations ranged from -0.13 (between YW and HU) to 0.95 (between EW and YW). These results indicated that selection based on EW may increase YW, AW and egg shell quality.</span> https://ijas.ut.ac.ir/article_62047_36c0bf7f91394c349aa831af6a2d8c0b.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effect of coating zeolite with nanosilver on performance and efficiency of energy and protein efficiency in broiler chickens Effect of coating zeolite with nanosilver on performance and efficiency of energy and protein efficiency in broiler chickens 69 75 62048 10.22059/ijas.2017.209825.653449 FA Niloofar Bolandi M. Sc. Student, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran Seyed Reza Hashemi Assistant Professor, Iranian Institute of Agricultural Biotechnology, Iran Daryoush Davoodi Assistant Professor, Iranian Institute of Agricultural Biotechnology, Iran Behrooz Dastar Professor, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran Saeed Hassani Associate Professor, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran Amin Ashayerizadeh Former M. Sc. Student, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran Journal Article 2016 06 15 This experiment was carried out to study the effect of coating zeolite with nanosilver on performance, energy and protein efficiency and the weight of liver, spleen and burs of fabricius in broilers, using 375 Cobb strain chicks in a completely randomized design with five treatments, five repetitions and 15 chicks in each replicate. Treatments were included basal diet and basal diet supplemented with one percent zeolite coated with different levels of nanosilver (zero, 0.25, 0.50 and 0.75 ppm). Broilers performance investigated weekly. Energy and protein efficiency were calculated in each period of production. On days of 21 and 42 two birds from each experimental unit were slaughtered to measure the weight of internal organs. The results didn’t show any significant different in weight gain and feed intake between exmerimental diets. The efficiency of energy and protein increased significantly on grower period and total period of production (p<0.05). By increasing the level of nanosilver, weight of liver and bursa were increased and decreased respectively (p<0.05). In conclusion according to the result of this research using zeolite coated with nanosilver can improve the efficiency of energy and protein in broiler chickens.  This experiment was carried out to study the effect of coating zeolite with nanosilver on performance, energy and protein efficiency and the weight of liver, spleen and burs of fabricius in broilers, using 375 Cobb strain chicks in a completely randomized design with five treatments, five repetitions and 15 chicks in each replicate. Treatments were included basal diet and basal diet supplemented with one percent zeolite coated with different levels of nanosilver (zero, 0.25, 0.50 and 0.75 ppm). Broilers performance investigated weekly. Energy and protein efficiency were calculated in each period of production. On days of 21 and 42 two birds from each experimental unit were slaughtered to measure the weight of internal organs. The results didn’t show any significant different in weight gain and feed intake between exmerimental diets. The efficiency of energy and protein increased significantly on grower period and total period of production (p<0.05). By increasing the level of nanosilver, weight of liver and bursa were increased and decreased respectively (p<0.05). In conclusion according to the result of this research using zeolite coated with nanosilver can improve the efficiency of energy and protein in broiler chickens.  https://ijas.ut.ac.ir/article_62048_d419cb0b98ef03ac2fc6debb248d9d4a.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effect of fiber-rich molting diets on performance, gastro intestinal fermentation and microbial activity of laying hens Effect of fiber-rich molting diets on performance, gastro intestinal fermentation and microbial activity of laying hens 77 87 62049 10.22059/ijas.2017.141826.653414 FA Ehsan Shahrami Researcher, Department of Animal Sciences, Qazvin Agricultural and Natural Resources Research and Education Center, Qazvin-Iran Journal Article 2016 01 28 <span>The objective of this experiment was to studythe effects of fiber-rich molting diets as alternative to the conventional feed withdrawal method, on performance, gastro intestinal fermentation and microbial activity of laying hens. One hundred eighty Hy-line (W36) laying hens were used in a completely randomized design with 5 treatments and 6 replicates by 12 birds in each replication during 12 days. Treatments were: 1- control group (</span><span>hens fed with a layer diet</span><span>), 2- feed withdrawal group, 3- laying hen diet containing 20000 mg zinc oxide/kg, 4- laying hen diet diluted by adding 90% alfalfa meal, 5- laying hen diet diluted by adding 90% palm kernel meal. Egg production of hen was monitored for 12 weeks during post molting period. Results show that<em> lactobacilli</em> and <em>Escherichia coli</em> bacteria population was significantly greater (P<0.05) in cecal contents of hens fed by palm kernel meal and withdrawal hens respectively than other treatments in the end of molting period. Also cecal total volatile fatty acids concentration was greater in hens fed by alfalfa than other treatments (P<0.05). The means of egg mass in fed treatments was generally higher than feed withdrawal and control treatments (P<0.05). The results suggest that fiber-rich diets compared to non-fiber diets and feed withdrawal lead to an increase in populations of useful bacteria and fermentation products and improvement of post molting production.</span> <span>The objective of this experiment was to studythe effects of fiber-rich molting diets as alternative to the conventional feed withdrawal method, on performance, gastro intestinal fermentation and microbial activity of laying hens. One hundred eighty Hy-line (W36) laying hens were used in a completely randomized design with 5 treatments and 6 replicates by 12 birds in each replication during 12 days. Treatments were: 1- control group (</span><span>hens fed with a layer diet</span><span>), 2- feed withdrawal group, 3- laying hen diet containing 20000 mg zinc oxide/kg, 4- laying hen diet diluted by adding 90% alfalfa meal, 5- laying hen diet diluted by adding 90% palm kernel meal. Egg production of hen was monitored for 12 weeks during post molting period. Results show that<em> lactobacilli</em> and <em>Escherichia coli</em> bacteria population was significantly greater (P<0.05) in cecal contents of hens fed by palm kernel meal and withdrawal hens respectively than other treatments in the end of molting period. Also cecal total volatile fatty acids concentration was greater in hens fed by alfalfa than other treatments (P<0.05). The means of egg mass in fed treatments was generally higher than feed withdrawal and control treatments (P<0.05). The results suggest that fiber-rich diets compared to non-fiber diets and feed withdrawal lead to an increase in populations of useful bacteria and fermentation products and improvement of post molting production.</span> https://ijas.ut.ac.ir/article_62049_d4fea33d6cb26474ae694b16f86190e8.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effects of of monensin supplementationalone or in combination with Methafix on ruminal fermentation and fatty acids composition of Longissimus Dorsi muscle in Farahani finishing lambs Effects of of monensin supplementationalone or in combination with Methafix on ruminal fermentation and fatty acids composition of Longissimus Dorsi muscle in Farahani finishing lambs 89 99 62060 10.22059/ijas.2017.200821.653425 FA Mohammad Taghi Alipour M. Sc. Student, Department of Animal Science, Lorestan University, Iran Arash Azarfar Associate Professor, Department of Animal Science, Lorestan University, Iran Ali Kiani Associate Professor, Department of Animal Science, Lorestan University, Iran Majid Khaldari Assistant Professor, Department of Animal Science, Lorestan University, Iran Journal Article 2016 02 15 This study was conducted to evaluate the effects of dietary inclusion of monensin alone or in combination with Methafix (a commercial product containing malate and fumarate) on rumen fermentation parameters and fatty acids composition of <em>longissimus dorsi</em> muscle (LD) of Farhani finishing lambs. Twenty four male Farhani lambs (4-6 months old, average body weight 35.9 ± 7.4 kg) were used. The lambs were randomly divided into four groups and individually fed with one of the four dietary treatments; control diet (Control), Control plus 24 mg of monensin/kg of DM (Monensin), control plus 4 g of Methafix/kg DM (Metafix) and Control plus 24 mg of monensin and 4 g of Methafix/kg DM (MonMet). Results showed that Monensin and/or MonMet decreased acetate (P<0.05) but increased propionate in comparision with control (P<0.05). Monensin, Metafizx and MonMetall had higher concentrations of lauric, myristic and margaric acids than control (P<0.05). However, palmitic, stearic and behenic acids content of LD were decreased by dietary supplementation with Monensin and metafix (P<0.05). Dietary treatments had no effect on LM concentrations of all mono-unsaturated fatty acids (except for nervonic acid), eicosatetraenoic, arachidonic, eicosaenoic and α-linoleic acids (P>0.05). However, dietary supplementation with M and ME increased LM concentrations of docosahexaenoic, docosatetraenoic, eicosapentaenoic and omega-3 fatty acids in comparison with control (P<0.05). In conclusion, both monensin and metafix seems to be promising agents for manipulation of rumen fermentation and fatty acid composition of meat in fattening Farahani lambs, however for revealing their functional mechanisms further research is needed. This study was conducted to evaluate the effects of dietary inclusion of monensin alone or in combination with Methafix (a commercial product containing malate and fumarate) on rumen fermentation parameters and fatty acids composition of <em>longissimus dorsi</em> muscle (LD) of Farhani finishing lambs. Twenty four male Farhani lambs (4-6 months old, average body weight 35.9 ± 7.4 kg) were used. The lambs were randomly divided into four groups and individually fed with one of the four dietary treatments; control diet (Control), Control plus 24 mg of monensin/kg of DM (Monensin), control plus 4 g of Methafix/kg DM (Metafix) and Control plus 24 mg of monensin and 4 g of Methafix/kg DM (MonMet). Results showed that Monensin and/or MonMet decreased acetate (P<0.05) but increased propionate in comparision with control (P<0.05). Monensin, Metafizx and MonMetall had higher concentrations of lauric, myristic and margaric acids than control (P<0.05). However, palmitic, stearic and behenic acids content of LD were decreased by dietary supplementation with Monensin and metafix (P<0.05). Dietary treatments had no effect on LM concentrations of all mono-unsaturated fatty acids (except for nervonic acid), eicosatetraenoic, arachidonic, eicosaenoic and α-linoleic acids (P>0.05). However, dietary supplementation with M and ME increased LM concentrations of docosahexaenoic, docosatetraenoic, eicosapentaenoic and omega-3 fatty acids in comparison with control (P<0.05). In conclusion, both monensin and metafix seems to be promising agents for manipulation of rumen fermentation and fatty acid composition of meat in fattening Farahani lambs, however for revealing their functional mechanisms further research is needed. https://ijas.ut.ac.ir/article_62060_d2992db3056833b741c409287a04b01b.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effect of Echinacea purpurea herbal extract on immune parameters in honey bee (Apis mellifera) Effect of Echinacea purpurea herbal extract on immune parameters in honey bee (Apis mellifera) 101 107 62338 10.22059/ijas.2017.133536.653366 FA Zahra Gorzin M. Sc. Student, University of Agricultural Sciences & Natural Resources University of Tehran, Karaj, Iran Hossein Moravej Associate Professor, University of Agricultural Sciences & Natural Resources University of Tehran, Karaj, Iran Gholam Ali Nehzati Paghale Asistance Professor, University of Agricultural Sciences & Natural Resources University of Tehran, Karaj, Iran Leyla Tabrizi Asistance Professor, University of Agricultural Sciences & Natural Resources University of Tehran, Karaj, Iran Journal Article 2015 10 05 This study investigated Echinacea purpurea herbal extract in honey bee nutrition and its effect immune system including measuring total haemocyte counts and phenoloxidase enzyme. 28 colonies were randomly divided into 4 treatments and 7 replicates.1- sugar syup – control, 2- sugar syrup enriched with 10 cc extract 3- sugar syrup enriched with 20 cc extract, 4- sugar syrup enriched with 30 cc extract. This experiment was conducted in the laboratory and Apiaries University of Tehran-Karaj in completely randomized design repeated in time during spring and summer of 2013. The results showed treatments had a significant effect on phenol oxidase enzyme activity in short and long-term immune (p<0.05), the enzyme was higher in bees that get sugar syrup enriched with 30 cc extract and lower in bees that get sugar syrup. In total haemocyte counts treatments had significant effect in short-term (p<0.05), the factor was highest was in bees that get sugar syrup enriched with 20 cc extract and lower in bees that get sugar syrup.too was observed that higher in bees that get sugar syrup enriched with 30 cc extract and lower in bees that get sugar syrup in long immune. The results showed that this extract had a positive effect on the immune system. This study investigated Echinacea purpurea herbal extract in honey bee nutrition and its effect immune system including measuring total haemocyte counts and phenoloxidase enzyme. 28 colonies were randomly divided into 4 treatments and 7 replicates.1- sugar syup – control, 2- sugar syrup enriched with 10 cc extract 3- sugar syrup enriched with 20 cc extract, 4- sugar syrup enriched with 30 cc extract. This experiment was conducted in the laboratory and Apiaries University of Tehran-Karaj in completely randomized design repeated in time during spring and summer of 2013. The results showed treatments had a significant effect on phenol oxidase enzyme activity in short and long-term immune (p<0.05), the enzyme was higher in bees that get sugar syrup enriched with 30 cc extract and lower in bees that get sugar syrup. In total haemocyte counts treatments had significant effect in short-term (p<0.05), the factor was highest was in bees that get sugar syrup enriched with 20 cc extract and lower in bees that get sugar syrup.too was observed that higher in bees that get sugar syrup enriched with 30 cc extract and lower in bees that get sugar syrup in long immune. The results showed that this extract had a positive effect on the immune system. https://ijas.ut.ac.ir/article_62338_8d3f6256a1e487292b5e5790913546b1.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Estimation of autosomal and sex-linked heritabilities for growth related traits in Markhoz breed of goats Estimation of autosomal and sex-linked heritabilities for growth related traits in Markhoz breed of goats 109 117 62339 10.22059/ijas.2017.226913.653501 FA Pouya Zamani Associate Professor, Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran Mohammd Almasi Ph.D Candidate, Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran Journal Article 2017 02 05 Separation of autosomal and sex-linked direct additive genetic effects has a high importance in breeding programs. This study was conducted to determine the autosomal and sex-linked additive genetic effects on growth related traits, using 17732 birth to yearling body weight records of Markhoz breed of goats in Sanandaj Markhoz Goat Breeding Center. In the models used to estimate variance components, birth year and season, sex, birth type and weighting age were fixed effects and direct autosomal additive genetic, direct sex-linked additive genetic, maternal additive genetic and maternal permanent environmental effects were considered as random effects. Variance components were estimated by Average Information algorithm of Restricted Maximum Likelihood by using Wombat software. For birth weight, weaning weight, pre-weaning daily weight gain and 6 month, 9 month and yearling weights, direct autosomal heritability estimates were 0.19±0.04, 0.13±0.03, 0.13±0.03, 0.12±0.03, 0.20±0.04 and 0.21±0.04, direct sex-linked heritability estimates were 0.03±0.02, 0.03±0.03, 0.02±0.03, 0.04±0.03, 0.07±0.03 and 0.07±0.03, maternal heritability estimates were 0.06±0.03, 0.05±0.03, 0.05±0.03, 0.05±0.03, 0.04±0.03 and 0.03±0.03 and coefficients of maternal environmental effects were 0.09±0.02, 0.05±0.02, 0.04±0.02, 0.05±0.02, 0.04±0.02 and 0.05±0.03, respectively. The findings showed that sex-linked genes possibly have negligible and close to zero additive genetic effects on body weights at initial ages and more noticeable effects on body weights at higher ages. Separation of autosomal and sex-linked direct additive genetic effects has a high importance in breeding programs. This study was conducted to determine the autosomal and sex-linked additive genetic effects on growth related traits, using 17732 birth to yearling body weight records of Markhoz breed of goats in Sanandaj Markhoz Goat Breeding Center. In the models used to estimate variance components, birth year and season, sex, birth type and weighting age were fixed effects and direct autosomal additive genetic, direct sex-linked additive genetic, maternal additive genetic and maternal permanent environmental effects were considered as random effects. Variance components were estimated by Average Information algorithm of Restricted Maximum Likelihood by using Wombat software. For birth weight, weaning weight, pre-weaning daily weight gain and 6 month, 9 month and yearling weights, direct autosomal heritability estimates were 0.19±0.04, 0.13±0.03, 0.13±0.03, 0.12±0.03, 0.20±0.04 and 0.21±0.04, direct sex-linked heritability estimates were 0.03±0.02, 0.03±0.03, 0.02±0.03, 0.04±0.03, 0.07±0.03 and 0.07±0.03, maternal heritability estimates were 0.06±0.03, 0.05±0.03, 0.05±0.03, 0.05±0.03, 0.04±0.03 and 0.03±0.03 and coefficients of maternal environmental effects were 0.09±0.02, 0.05±0.02, 0.04±0.02, 0.05±0.02, 0.04±0.02 and 0.05±0.03, respectively. The findings showed that sex-linked genes possibly have negligible and close to zero additive genetic effects on body weights at initial ages and more noticeable effects on body weights at higher ages. https://ijas.ut.ac.ir/article_62339_95b573aec543793f9ee37a5acb806df5.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Comparison of the effects of Zilmax® and different doses of Ajwain essential oil as β-agonist drugs on performance and serum biochemical metabolites in parental line of a commercial broiler Comparison of the effects of Zilmax® and different doses of Ajwain essential oil as β-agonist drugs on performance and serum biochemical metabolites in parental line of a commercial broiler 119 127 62340 10.22059/ijas.2017.99302.653188 FA Farhad Samadian Assistant Professor, Faculty of Agriculture, Yasuj University, Iran Armin Towhidi Associate Professor, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Saeid Zeinodini Associate Professor, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Mohammad Amir Karimi Torshizi Assistant Professor, Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran Hossein Vaseghi Former M. Sc. Student, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Journal Article 2014 05 02 This study was performed to investigate the effect of dietary supplementation with ajwain essential oil (EO) and zilmax^® on performance, carcass traits and serum biochemistry of chicks that were reared under different thermal programs. Another purpose of present study was to explore cold stress effects on above-mentioned parameters. This study were done according to a Complete Randomized Design with 8 treatment. For this purpose, Four dietary treatments (basal diet, dietary addition of ajwainEO at 150 and 450 ppm and zilmax^®at 1.6 ppm) each with corresponding replicates (24 replicate; n=192; one male chick in each individual cage as a replicate) were fed to chicks at two different thermal programming envirnment. The results showed that at normal temperature envirnment, dietary addition of zilmax^® and 450 ppm Ajwain EO, have increased plasma levels of triglycerides at the end of the growing phase (29 d) compared to control. Cold stress significantly decreased performance and ralitive weight of bursa (P>0.05). In conclusion, ajwain EO and and zilmax^®as a feed additive had no beneficial effects on performance and could not ameliorate the negative effects of cold stress on chicks. This study was performed to investigate the effect of dietary supplementation with ajwain essential oil (EO) and zilmax^® on performance, carcass traits and serum biochemistry of chicks that were reared under different thermal programs. Another purpose of present study was to explore cold stress effects on above-mentioned parameters. This study were done according to a Complete Randomized Design with 8 treatment. For this purpose, Four dietary treatments (basal diet, dietary addition of ajwainEO at 150 and 450 ppm and zilmax^®at 1.6 ppm) each with corresponding replicates (24 replicate; n=192; one male chick in each individual cage as a replicate) were fed to chicks at two different thermal programming envirnment. The results showed that at normal temperature envirnment, dietary addition of zilmax^® and 450 ppm Ajwain EO, have increased plasma levels of triglycerides at the end of the growing phase (29 d) compared to control. Cold stress significantly decreased performance and ralitive weight of bursa (P>0.05). In conclusion, ajwain EO and and zilmax^®as a feed additive had no beneficial effects on performance and could not ameliorate the negative effects of cold stress on chicks. https://ijas.ut.ac.ir/article_62340_7afc338b40826861b8b684b9efdabcb6.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 Effect of canola peptides, antibiotic, probiotic and prebiotic on performance, digestive enzymes activity and some ileal aerobic bacteria in broiler chicks Effect of canola peptides, antibiotic, probiotic and prebiotic on performance, digestive enzymes activity and some ileal aerobic bacteria in broiler chicks 129 139 62342 10.22059/ijas.2017.221313.653481 FA Sadegh Karimzadeh Ph. D. Student, Faculty of Animal Science and Fisheries, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran Mansour Rezaei Assistant Professor, Faculty of Animal Science and Fisheries, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran Asadolah Teimouri-Yansari Associate Professor, Faculty of Animal Science and Fisheries, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran Journal Article 2016 12 06 The aim of the present experiment was to evaluate the effect of canola peptides (produced by enzymatic hydrolysis of canola meal), antibiotic, probioticand prebioticongrowth performance, digestive enzymes activity and some aerobic bacteriain broiler chicks. The experiment was conducted in a completely randomized design with 5 treatments 4 replicates of 10 male chicks each. Broiler chicks were fed on a diet with no feed additive (Control) or containing, 200 mg /kg antibiotic, 1 g /kg prebiotic, 400 mg/kg probiotic and 250 mg /kg canola peptides from day 1 to 42 of age. Results indicated that addition of canola peptides and probiotic to diet increased (P<0.05) body weight gain and decreased feed conversion ratio during days 11 to 28 d and 1 to-42 of age compared to the other groups (P<0.05). No significant differences observed among experimental treatments for feed intake. Digestive amylase, lipase and protease activity in chickens fed with 250 mg /kg canola peptides was greater than birds receiving other supplemented birds (P<0.05). Adding canola peptides and probiotic increased ileal <em>Basiluss</em> count compared to the other experimental treatments.It is  Conclued that canola peptides increased body weight gain, decreased feed conversion ratio, increased intestinal amylase, lipase and protease activity, and ileal <em>Basiluss</em> count compared to the other experimental treatments. The aim of the present experiment was to evaluate the effect of canola peptides (produced by enzymatic hydrolysis of canola meal), antibiotic, probioticand prebioticongrowth performance, digestive enzymes activity and some aerobic bacteriain broiler chicks. The experiment was conducted in a completely randomized design with 5 treatments 4 replicates of 10 male chicks each. Broiler chicks were fed on a diet with no feed additive (Control) or containing, 200 mg /kg antibiotic, 1 g /kg prebiotic, 400 mg/kg probiotic and 250 mg /kg canola peptides from day 1 to 42 of age. Results indicated that addition of canola peptides and probiotic to diet increased (P<0.05) body weight gain and decreased feed conversion ratio during days 11 to 28 d and 1 to-42 of age compared to the other groups (P<0.05). No significant differences observed among experimental treatments for feed intake. Digestive amylase, lipase and protease activity in chickens fed with 250 mg /kg canola peptides was greater than birds receiving other supplemented birds (P<0.05). Adding canola peptides and probiotic increased ileal <em>Basiluss</em> count compared to the other experimental treatments.It is  Conclued that canola peptides increased body weight gain, decreased feed conversion ratio, increased intestinal amylase, lipase and protease activity, and ileal <em>Basiluss</em> count compared to the other experimental treatments. https://ijas.ut.ac.ir/article_62342_40d8588419e3536e9b5c124883042700.pdf

پردیس کشاورزی و منابع طبیعی دانشگاه تهران Iranian Journal of animal Science 2008-4773 48 1 2017 05 22 The effect of Letrozole on frozen-thawed sperm quality and fertility of broiler breeder roosters The effect of Letrozole on frozen-thawed sperm quality and fertility of broiler breeder roosters 141 151 62343 10.22059/ijas.2017.225029.653494 FA Mahbub Mohammadi M.Sc. student, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Ahmad Zare-Shahaneh Professor, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Saeid Zeinoaldini Associate Professor, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Mahdi Ansari Ph.D. Condidate, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran Journal Article 2017 01 15 This study was carried out to evaluate the effect of the oral administration of Letrozole on blood testosterone level and frozen-thawed sperm quality and fertility of broiler breeder roosters. Twenty 50-week-old Ross 308 roosters were randomly divided into four groups (five roosters per each), individually housed in pens and received 0 (Control), 0.5 (L0.5), 1 (L1) or 1.5 (L1.5) mg Letrozole/bird/day. Semen and blood collections were done weekly for seven and six weeks, respectively. Sperm quality parameters including total and forward motility, viability and plasma membrane functionality were assessed prior freezing and these parameters along with abnormality were evaluated using post-thawed semen samples. The last three weeks were frozen and artificially inseminated to evaluate sperm penetration and fertility rate. According to the results, total and forward motility and viability of fresh and frozen-thawed sperm were significantly higher in Letrozole treated groups compared to control group. Plasma membrane functionality of fresh and frozen-thawed sperm as well as penetration and fertility rates were significantly improved in both L_0.5and L₁ groups compared to control group. However, blood testosterone level was significantly higher in L_1.5than control group. In spite of observing negative effects in 1.5 level, both 0.5 mg of Letrozole/bird/day could improve sperm freezability of roosters, however, further research are needed to ascertain this results. This study was carried out to evaluate the effect of the oral administration of Letrozole on blood testosterone level and frozen-thawed sperm quality and fertility of broiler breeder roosters. Twenty 50-week-old Ross 308 roosters were randomly divided into four groups (five roosters per each), individually housed in pens and received 0 (Control), 0.5 (L0.5), 1 (L1) or 1.5 (L1.5) mg Letrozole/bird/day. Semen and blood collections were done weekly for seven and six weeks, respectively. Sperm quality parameters including total and forward motility, viability and plasma membrane functionality were assessed prior freezing and these parameters along with abnormality were evaluated using post-thawed semen samples. The last three weeks were frozen and artificially inseminated to evaluate sperm penetration and fertility rate. According to the results, total and forward motility and viability of fresh and frozen-thawed sperm were significantly higher in Letrozole treated groups compared to control group. Plasma membrane functionality of fresh and frozen-thawed sperm as well as penetration and fertility rates were significantly improved in both L_0.5and L₁ groups compared to control group. However, blood testosterone level was significantly higher in L_1.5than control group. In spite of observing negative effects in 1.5 level, both 0.5 mg of Letrozole/bird/day could improve sperm freezability of roosters, however, further research are needed to ascertain this results. https://ijas.ut.ac.ir/article_62343_2482f7347c7b3ad016ccf1cad8c86889.pdf