m. sari

Introduction :

Expressed Myostatin gene in the muscles is a member of the TGF-β family. It extends skeletal muscle and regulates the activity of muscle fibers.The Myostatin gene (GDF-8) works as a negative regulator of the skeletal muscle growth. Mutation in the Myostatin sequence changes its regulating function and results in the growth and hypertrophy of the muscles. Mutation in Myostatin has been found in various species. This gene has three exons and two introns in all species. Mutant alleles are significantly correlated with the growth rate and desired carcass traits and increase the ratio of muscle to fat and bone. Cross breeding is a common method of exploiting the genetic differences between different breeds and increasing the ability of individuals which is often considered as the quickest way to improve the sheep production efficiency.This study was conducted to investigate the effect of cross breeding on the Myostatin genes in Arabi lambs and its cross with Romanov.

At the beginning of the experiment, the similar ewes were artificially inseminated with Romanove ram sperm by laparoscopy method after estrous synchronization. Born lambs were kept in similar conditions.For this purpose, 16 Arabi and hybrid lambs were used in a completely randomized design with two treatments and eight replicates. After slaughter, the meat samples were immediately collected from right side of  longissimus lumborum muscle and transferred to the lab in liquid nitrogen and stored at -80 °C. RNA extraction was performed using the Trizol (Easy Blue) method. The quantity and quality of the extracted RNA were determined using a spectrophotometer (Thermo Scientific, Nanodrop, 2000C, USA) from 260 to 280 and 1% agarose gel (20 minutes at 100 volts). Total RNA quality was checked after extraction and used to produce cDNA. Synthesis of cDNA was made using the (Gene All) cDNA build kit in accordance with the manufacturer’s instructions. The designing of the forward and reverse primers for the Myostatin gene and the reference one of Glyceraldehyde 3-phosphate dehydrogenase was performed using the Primer Quest program on the IDT site (Integrated DNA Technologies). Finally, the expression of Myostatin gene was evaluated by Real-time qPCR. Glyceraldehyde 3-phosphate dehydrogenase gene as housekeeping one was used to normalize the data. SAS and REST softwares were used to analyze the final weight and gene expression data, respectively.

Results and discussion:

 cDNA synthesis was accomplished after extracting the RNA and measuring its purity. After the cDNA synthesis and dilution, the PCR reaction was performed. Following the successful replication of the desired fragments of Myostatin genes and Glyceraldehyd 3-phosphate dehydrogenase, the observation of the products in the agarose gel with the ladder confirmed the correctness of the fragments size. The size of the replicated fragments for the Myostatin and Glyceraldehyd 3-phosphate dehydrogenase genes are 81 and 144 bp, respectively. After ensuring the efficiency of the designed primers, the Real Time PCR reaction was performed in two replicates for each cDNA sample. The information obtained was sorted and analyzed. Results indicated that the highest mean of the target gene in Arabi breed and the lowest one in the crossbred group. The difference between the Arabi and crossbred group was significant (p < 0.05). The results indicated that the crossbreeding caused a significant reduction in the Myostatin gene expression. The expression of Myostatin gene in Arabi race was 1.4 fold greater than that in the cross bred group. This was in concordance with the final lamb weights which were significantly different for the two groups. The final weight in the cross bred lambs were higher than the Arabi counterparts.

Conclusion:

 Based on the obtained data, the current investigation was the first study in the field of Myostatin gene expression in Arabi×Romanove cross breeding. In overall, the results showed that the cross breeding can significantly affect the expression of the studied gene.  Regarding the effect of Myostatin gene on the muscle function, decreased Myostatin gene expression may influence the final weight gain. As this study showed the effect of crossbreeding on Myostatin gene expression, it is necessary to consider the consequences of crossbreeding on the native sheep breeding programs. This study could help in more understanding the cross breeding effects on the livestock performance

The purpose of this study is to analyze the two-phase flow in the recirculation region of a gas turbine combustion chamber by changing the effective geometrical parameters of its swirler. The natural and forced rotational flows caused by the geometry of the combustion chamber and flow field conditions have significant effects on combustion and air-fuel mixing. In this study, finite volume method and unstructural meshing are used in a commercial computational fluid dynamics software package in order to investigate the effects of rotational flow injection in combustion chamber and to carry out a parametric study. The obtained results show the volume of the recirculation zone in the primary area of the combustion chamber increases as the swirl number rises. This increases the turbulence intensity and improves air-fuel mixing.

Red meat is one of the best dietary sources of fat and protein for humans. The fatty acid composition of meat has long been studied, but still receives a lot of attention in research because of its implications for human health. Besides a lower total fat intake, human nutritionists are recommending a higher intake of polyunsaturated fatty acids, and especially of n-3 fatty acids at the expense of n-6 fatty acids. Numerous animal feeding trials have been carried out using different species and breeds aiming at bringing the polyunsaturated fatty acid/saturated fatty acid (P/S) ratio of meat closer to the recommended value (>0.7), as well as for the n-6/n-3 ratio (<5). Sugar beet pulp (SBP) contains 70% carbohydrates mainly as neutral detergent soluble fiber, which has high water-binding capacity and a slow fermentation rate in rumen compared to the barley grain. Replacing barley with SBP may overcome digestive disorders such as acidosis problem and lead to the utilization of dietary energy towards animal growth, carcass gain, and muscle intramuscular fat deposition. On the other hand, feeds containing fats and oils are being used in animal diets to increase energy density and to manipulate intramuscular fat content and fatty acid composition of the meat. Canola seed contains approximately 40 to 43 % oil in which oleic acid, linoleic acid, and α-linolenic acid contribute to 61, 20 and 10%, respectively. High fat content of canola seed makes it an attractive feedstuff to improve energy density of diets for finishing lambs grown in dry regions, where pasture availability is low. To our knowledge, information containing the effects of SBP as a slow fermentable carbohydrate source with an inclusion of roasted canola seed on growth performance and meat quality characteristics of fattening lambs is not investigated. The objective of this study was to evaluate the effects SBP with or without RCS in a high concentrate diet on performance and muscle composition of Arabian fattening lambs. This experiment was approved by the Animal Care and Ethics Committee of Ramin University of Livestock Research. In this study, twenty-four Arabian male lambs, 4 months old, (23.7±2.5 kg; mean initial BW±SD) were kept in individualcages (1.4×1.2 m). The fattening period was 99 d including 14 d as adaptation period. At the start of the adaptation period, all the animals were treated for external and internal parasites and vaccinated against enterotoxaemia. The animals were randomly assigned to one of the four dietary treatments included 1) starch, 2) starch with roasted canol seeds, 3) Neutral detergent soluble fiber and 4) Neutral detergent soluble fiber with roasted canola seed. The diets were offered to animals to meet the requirements of growth rate at 250 g/day according to National Research Council (NRC, 2007). Lambs were weighed weekly throughout the experimental period prior to the morning feeding. Feed conversion ratio was calculated as the ratio between average daily intake and average daily gain. Average daily gain was calculated for each sheep from regression analysis of live weight vs. time from day 1 to 99 of each treatment. At the end of the trial, all the animals were slaughtered according to Halal method. Samples from Longissimus dorsi (LD) between 5th and 6th ribs trimmed of all external subcutaneous fat were collected. These were used to determine moisture, crude protein, fat, and ash contents of meat according to Association of Official Analytical Chemistry (AOAC, 2006). Lightness (L*), rednes (a*), and yellowness (b*) of meat samples were measured using a Minolta CR-300 colorimeter in the CIE L*a*b*. Hue angle (H*) was calculated as tan−1 (b*/a*) × (180/π) and Chroma (C*) as (a*2+b*2)1/2. The colorimeter was set for using the illuminant A and 10° standard observers. About 50 g of the LD muscle between 6th to 9th ribs were taken for determination of fatty acid profiles. Muscle lipids were extracted as described by Folch et al. (1957), using dichloromethane and methanol (2:1 vol/vol), instead of chloroform and methanol (2:1 vol/vol), and were methylated according to Metcalfe and Schmitz (1961). The transmethylated samples were analyzed by a gas chromatograph with a flame ionization detector and a capillary column measuring 100 m in length × 0.25 mm i.e., with a thickness of 0.20 mm. Helium was used as the carrier gas at a flow rate of 1 mL/min. Also, tridecanoic acid (C13:0) was used as internal standard. The initial temperature of the oven was 70 °C and was increased by 10 °C/min to 175 °C, where it was maintained for 25 min. The temperature was then increased by 7 °C/min to 220 °C, where it was maintained for 10 min, followed by another increase by 10 °C/min to 230 °C, where it remained for 4 min. The temperature of the injector was 280 °C, and the temperature of the detector was 300 °C. Identification of the fatty acids was carried out by comparison of the retention times with standards of fatty acids from butter, and the percentage of fatty acids was obtained by means of Chromquest 5.5 software. Performance data were analyzed completely random design with repeated measurement PROC MIXED and compound symmetry model. Meat Characteristics data were as a completely randomized design with a 2×2 factorial arrangement using PROC GLM in SAS software. Partial replacement of starch with soluble fiber significantly increased performance concentration of capric, c17:0 anteiso and behenic acid and significantly reduced lauric, heptadecanoic, oleic, linoleic and polyunsaturated fatty acids of longissimus dorsi (P<0.05). Addition of roasted canola seed to diets increased performance (average 288 g vs. 262 g) and reduced the concentration of isopalmitic and behenic acid and significantly increased concentration of Lauric, Myristic, Anteiso-pentadecanoic, Pentadecenoic, Palmitic, Palmitoleic, Stearic, Vaccenic, Conjugated linoleic, Oleic, α-Linolenic, γ-Linolenic, Gondoic, Docosatetraenoic, h-γ-Linolenic, Arachidonic, Eicosapentaenoic, Nervonic, Docosapentaenoic, Docosahexaenoic acids and the total concentration of unsaturated fatty acids with one or polyunsaturated fatty acid pattern longissimus dorsi (p<0.05). Canola seed addition significantly increased n-6/n-3 and p/s ratio (P<0.05). Replacement of starch with soluble fiber significantly decreased and fat addition significantly increased meat cholesterol concentratin (P<0.05). The results showed that the use of canola seeds by changing the indicators of unsaturated fatty acids, omega-6 to omega-3 ratios reform and polyunsaturated fatty acids to saturated fatty acids
can improve the quality and quantity of meat.

In order to investigate effects of addition of Salvia mirzayanii essence and comparison with antibiotic an experiment was conducted as dietary a completely of the randomized design with 5 treatments، and 5 replicates with 12 chickens per replicate for 42 days with treatments control، virginiamycin antibiotic 10% (100 ppm) and three levels of S. mirzayanii essence (200، 400 and 600 ppm). Weight gain and feed intake recorded weekly and carcass characteristics analysis and blood parameters were determined at 28 and 42 days of age. Highest weight gain was observed at the level of 200 ppm essence at the 22-42 days of age (grower phase) and at1-42 days of age (total of experiment)، 200 and 600 ppm essence showed the highest results. Feed intake was highest in 200 and 600ppm essence level in the grower phase as well as overall. Best feed conversion ratio at the grower phase and total of experiment observed in the 200 ppm essence treatment. Gizzard and gastrointestinal tract weights significantly decreased with addition of antibiotic. This essence significantly decreased cholesterol، HDL and LDL. Bursa of fabricius weight was significantly highest at level of 400 ppm essence and lowest at the level of 600 ppm. Dietary addition of essence significantly decreased blood eosinofil. The results of this experiment showed that S. mirzayanii essence could be used as growth promoter and using low levels of the essence could improve performance and immune system.