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

Copy number variation (CNV) consist of deletion, insertion, and duplications. It is an important source of genetic variation in organisms and thus influences on the gene expression and phenotypic variation. Copy number variation (CNV) is one of the structural variant with an intermediate size class larger than 50bp which involves unbalanced rearrangements that increase or decrease the amount of DNA (Pirooznia et al 2015, Alkan et al 2011). The size of CNVs is larger than 50bp, while smaller segments are known as insertions or deletions (indels). Thereupon these structural variations comprise more polymorphic than SNPs because of enormity, detection of them and their effect on phenotype has caught the attention of many researchers recently. It has been reported that CNVs changes in gene dosage and regulation as well as in transcript structure, and thus contribute to phenotypic variability (Pirooznia et al 2015, Alkan et al 2011). The pea-comb phenotype is caused by a CNV mapping to intron 1 of the SRY (sex determining region Y)-box 5 (SOX5) gene (Wright et al. 2009). Late feathering in chickens is due to incomplete duplication in PRLR and SPEF2 genes (Elfrink et al. 2008). In swine, dominant white colour has been related with a duplication of a 450-kb fragment of the KIT gene (Giuffra et al. 1999) and a splice mutation causing the skipping of exon 17 (Giuffra et al. 1999). In sheep, doubling in the ASIP gene results in the regulation of pigment in body coat (Norris et al. 2008). Doubling the 4.6 k base pair into the six introns of the STX17 gene results in a gray body color in the horse with age. Deletion of the intergenic region with a length of 11.7 kbp in the goat genome leads to the removal of horns (Clop et al. 2012). Chicken is the most intensively farmed animal on earth and is a major food source with billions of birds used in meat and egg production each year. A big share of chicken CNVs involves protein coding or regulatory sequences. A comprehensive study of chicken CNV can provide valuable information on genetic diversity and assist future analyses of associations between CNV and economically important traits in chickens. Unique chicken genome with macro and micro chromosomes and its biology make it an ideal organism for studies in development and evolution, as well as applications in agriculture and medicine (Burt 2005). In the last several years, There has been an increasing interest in the study of CNVs in the chicken. This study focuses on comparison of CNV between the broilers and layers chicken to find evidence of domestication on the genome using whole genome sequencing.

we used n=90 female birds of two commercial broiler (n=40) and layer (n=50) chicken. The broilers (BRs) were represented by 20 DNA samples of each of two lines (BRA and BRB) established independently and previously collected as part of the AVIANDIV project. In the layer group (LRs), data from 25 birds each from purebred white (WL) and brown (BL) egg laying populations, sequenced in the frame of the SYNBREED project (http://www.synbreed.tum.de/index.php?id=2 ,(were included. The paired-end reads with a read length of 101bp were mapped against the current reference genome assembly Galgal6 using the Burrows-Wheeler aligner (bwa, 0.6.2-r126 Version, with default parameters. Duplicate reads were masked during post-processing using the Picard tool set (version 2.9.2, http://picard.sourceforge.net). Finally, Genome Analysis Toolkit-3.3.0 was used to realign reads for correcting errors caused by InDels. Using GATK software package and Depth Of Coverage function (McKenna et al 2010), the depth of readings was calculated for each sample. Then filter out reads with mapping quality below 20. Because comparing the genomes of individuals in different groups was time consuming and computationally difficult for all parts of the genome, the genomes of each individual were divided into 1000 bp non-overlapping windows and the average reading depth per window was calculated. Then the results were normalized against the BL sample that showed highest average depth. In short, we created a correction factor per population and applied it on the depth of coverage value for each window. For all the contrasts, we performed an analysis of variance (ANOVA) as described (Carneiro et al 2014). For the Broilers-Layers contrast we scanned 935247 windows. 70372 windows showed significant by FDR with P < 0.001, with ANOVA using the Benjamini-Hochberg FDR method for multiple corrections (Benjamini and Hochberg 1995).

Mapping sequencing data to galGal6 assembly showed an average 98.61% mapping rate and 11.51 depth. Manhattan plot was plotted for regions of the genome that differed significantly between the two groups (FDR = 0.001). The points above the hypothetical line were identified and examined in a 25 Kbp confidence interval to identify possible genes. 39 regions were identified that half of them dose not contain any genes. Although Long noncoding RNAs are under lower selective pressure than protein-coding genes (Batista and Chang 2013), The other 11 regions contained 16 genes related to long non-coding RNAs. Long noncoding RNAs (lncRNAs) play a critical role in organizing the 3-dimensional genome architecture and regulating gene activity in cis or in trans through multiple mechanisms (Zhang et al 2019, Batista and Chang 2013). 6 othere regions also contained 12 coding genes. Most of the identified genes were somehow linked to the immune system disease or cancer. Genes such as DEDs and TNFAIP8 are involved in programmed cell death (apoptosis) and two genes NPAL3 and RCAN, which are involved in the immune system, had a copy number variation in the studied samples. In addition RCAN is involved in Down syndrome. The PFDN gene, located on chromosome 25, is also involved in Alzheimer's and Parkinson's disease.

Guanidinoacetic acid (GAA), a creatine precursor, is synthesized from L-arginine and glycine. The capacity for de novo synthesis may be limiting in high-yielding farm animals, especially in those fed all-vegetable diets. As the precursor to creatine, dietary GAA can also effectively “spare” arginine from being used for GAA synthesis, so that the arginine may be used for muscle accretion and other physiological functions. It has been reported that arginine affects bone development by its involvement in the formation of collagen and connective tissue. It also has been shown that reducing the protein level in broiler diets reduces the concentration of manganese and copper in the tibia. Therefore, low-protein diets probably decrease bone density in broilers. This study was conducted to investigate the effects of GAA supplementation to low protein diets on performance, calcium and phosphorus and the strength of the tibia of broiler chickens.

  The 240 male broilers of Ross 308 strain were assigned to 6 dietary treatments in a 3 × 2 factorial arrangement with 4 replications and 10 birds in each replication. Dietary treatments included diets containing 80, 90 and 100% of the breeder recommended ideal protein each containing 0 and 0.06% of GAA. Feed intake, body weight gain and feed conversion ratio (FCR) were measured for the grower (11-24 days), finisher (25-42 days) and the overall period (11-42 days). On d 42, two birds from each experimental unit were killed, and the ash, calcium and phosphorus content and the strength of the tibia of the chickens were measured.

The results showed that by reducing the ideal protein to 80% of the breeder recommendation, body weight gain and feed intake was reduced significantly (P<0.05). Reduction of the dietary CP from 100 to 80%, resulted in inferior FCR during grower period. The inferior performance of broilers fed reduced protein diets is attributed to a limited availability of amino acids (AA). The supplementation of essential AA alone has failed to increase performance in reduced protein diets. The addition of GAA decreased feed intake of treatments (P<0.05) with reduced protein diet (80% of management guide recommendation). Body weight gain and FCR were not affected by dietary GAA supplementation. By reducing dietary protein to 80% of the recommendation, the strength of tibia decreased significantly (P<0.05). A low-protein diet may be associated with a hypocalciuretic effect, increased Ca retention and requirement for available P to avoid Ca:P imbalance, hormonal flux, and bone mobilization. Addition of GAA to the diet did not affect the parameters of bone strength. Tibia ash, Ca and P content were not significantly affected by dietary treatments.

According to the results of this experiment, reducing the dietary ideal protein to 80% of the breeder recommendation, resulted in inferior growth performance and tibia strength of broiler chickens, and dietary addition of GAA did not ameliorate those effects.

Effect of different sources of probiotic and prebiotic on growth performance, carcass characteristics, intestinal microflora, and blood metabolites using 720 Ross 308 commercial male broiler chickens in a 3×3 factorial experiment with three levels of probiotic (without probiotic, probiotic type I and type 2) and three levels of prebiotic (without prebiotic, prebiotic type 1 and type II), in a completely randomized design with nine experimental groups (four replications and 20 birds were studied in each replication. Birds that were fed with diets containing type 2 probiotics had a lower conversion factor (P<0.05). Diets containing prebiotic type 1 as well as diets containing probiotic type II and diets containing probiotic type II and two prebiotics under test reduced serum cholesterol and LDL concentrations (P < 0.05). The effect of the experimental treatments on carcass fat was not significant, but the birds fed diets containing prebiotic type 1 had less abdominal fat (P<0.05). At 21 days old, the population of E. coli in the ileum and ceca of birds that received probiotics, prebiotics, and their combinations decreased (P < 0.05). At 38 days of age, feeding the birds with probiotics and prebiotics and a combination of them reduced the population of E. coli in the ceca and increased lactobacillus in the ileum (P < 0.05). The results of this experiment showed that probiotics or prebiotics assayed in this study have positive effects on the increase of beneficial intestinal bacteria (Acid lactic bacteria), blood biochemical traits, and FCR in broiler chickens.

Ascites is one of the most common metabolic syndromes in today's fast-growing broilers and is associated with rapidly growing tissues and characterized by accumulation of lymph fluid in the peritoneal spaces. Effective factors in the occurrence of ascites syndrome include free radicals in the body such as superoxide, hydroxide, and hydrogen peroxide. By reducing the capacity of the body's antioxidant systems, free radicals make the bird susceptible to various diseases. Free radicals produced in the body by damaging the cell membrane lead to cell death and ultimately tissue damage. Therefore, by increasing cell protection from such injuries, one of the common causes of ascites and heart failure abnormalities can be prevented. In addition, free radicals from oxygen derivatives reduce the half-life of nitric oxide (vasodilating agent), causing a decrease in the ability of vasodilation and providing the basis for the occurrence of ascites. Therefore, it is suggested that the use of antioxidants can prevent ascites and improve performance in broilers. Medicinal plants are among the rich sources of natural antioxidants that do not have the harmful effects of antibiotics and synthetic antioxidants. For this reason, the use of medicinal plant extracts is an important step in animal nutrition to increase the immunity of poultry. The mentioned extracts have strong antioxidant, antibacterial, and digestive properties. Probably, the positive effects of medicinal plants are due to the active compounds found in plant extracts such as menthol, thymol, and carvacrol. This study aimed to investigate the effects of ethanolic extract of sage on the performance, antioxidant status, and blood parameters of broiler chickens under induced ascites.
A total of 450 one-day-old chickens (Ross 308) were reared in the form of a completely randomized design with six treatments and five replications (15 chickens in each replication). Experimental treatments include 1. Positive control group (without inducing ascites and fed with basic diet), 2. Negative control group (inducing ascites and fed with basic diet), 3 and 4. Vitamin C group (inducing ascites with levels of 1000 and 2000 ppm vitamin C), 5 and 6- Sage group (ascites induction with 1000 and 2000 ppm of sage extract). To induce ascites, water containing 1200 mg of sodium (three grams per liter of sodium salt) was provided to the chickens from the 15th day of the experiment. Growth performance parameters including feed intake, weight gain, and feed conversion ratio were calculated for the total period. On the last day of the experiment (42 d), two birds were randomly selected from each cage and after sampling from the wing vein, killed and the ascites index was calculated as the ratio of the weight of the right ventricle to the total ventricles. The mortalities were collected as soon as they were observed and after weighing to correct the feed conversion ratio, were necropsied to investigate the cause of death. Blood and biochemical parameters such as the number of red and white blood cells, hemoglobin, hematocrit, heterophil and lymphocyte, serum triglyceride, and cholesterol, as well as serum antioxidant parameters including the level of malondialdehyde and the activity of antioxidant enzymes including glutathione peroxidase, superoxide dismutase, and catalase were measured. In addition, liver enzymes present in the serum including alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), and alkaline phosphatase (ALP) were also measured.
The results showed that induction of ascites increased the ratio of the right ventricle to total ventricles, mortality due to ascites, feed consumption, feed conversion ratio, and body weight loss (P<0.05). Administering sage extract improved the mentioned traits and vitamin C also reduced the ratio of right ventricle to total ventricles, losses due to ascites (P<0.05). Sage extract and vitamin C moderated the increasing effects of ascites induction on heterophiles, triglyceride, and cholesterol and increased red blood cells, hematocrit, and hemoglobin compared to the negative control treatment (P<0.05). In addition, the induction of ascites decreased the activity of glutathione peroxidase, superoxide dismutase, and catalase enzymes and increased serum malondialdehyde, experimental treatments, especially sage extract, improved the antioxidant status compared to the negative control treatment (P<0.05). Also, the induction of ascites increased the serum levels of aspartate aminotransferase, alanine aminotransferase, gammaglutaryl transferase, and alkaline phosphatase enzymes. The addition of experimental supplements, especially sage, decreased the serum level of the mentioned enzymes (P<0.05).
The results of this research showed that the use of sage extract compared to vitamin C has better results on performance, increasing antioxidant power, and reducing stress of broilers with ascites.

The use of medicinal plants and their derivatives can stimulate feed consumption, increase daily weight, feed conversion ratio, increase shelf life, improve the health and function of the digestive system. It seems that the use of an optimal mixture of several medicinal plants in the diet has positive effects on performance and carcass quality of broiler chickens in comparison to each one. Nowadays, with the popularization of ready-made feed in raising broiler chickens, many breeders tend to add food additives in drinking water. Therefore, it is a question that adding these compounds in feed or drinking water makes a difference. Three commercial plant additives that are used today are Coxan, O.X. Plant, and Entex. Coxan contains oregano (with the active ingredient of menthol) and garlic (with the active ingredients of allin and allicin), O.X. Plant contains savory (with the active ingredients of carvacrol and thymol), thyme (with the active ingredients of thymol and carvacrol) and red pepper oleoresin (with the active ingredient of capsaicin), Entex contains cinnamon (with the active ingredient of cinnamaldehyde), and garlic and eucalyptus (with the active ingredient of cineol). The aim of this research was to compare the effects of using these commercial plant additives (in water and feed) on growth performance, intestinal microflora and morphology and immune response of broilers.
A total of 336 Ross 308 broilers were examined in a completely randomized design with seven treatments, four replications, and 12 chickens per replication. Experimental treatments included: control (without phytogenic in feed or water), Coxan in feed (300 mg/kg) and in water (200 mL/1000 L), O.X. Plant in feed (200 mg/kg) and in water (135 mL/1000 L) and Entex in feed (500 mg/kg) and water (350 mL/1000 L). Daily weight gain, daily feed intake, daily water intake and feed conversion ratio were measured. At 42 days of age, two birds were selected from each experimental unit and after slaughter, the length of the intestinal components was measured separately (duodenum, jejunum, and ileum). To determine the microbial population, samples were taken from the ileum of chickens. EMB culture medium was used to determine Escherichia coli population and MRS culture medium was used for Lactobacillus bacteria. To check the humoral immune response, 0.1 mL of 25% sheep red blood cell solution in PBS was injected into the breast muscle of chickens on the 12th and 29th days of rearing. Blood was taken from the chickens on the 28th, 35th and 42nd days of breeding and the levels of Anti-SRBC, and immunoglobulins G and M were calculated. Antibody titer against Newcastle disease was measured by HI method.
The effect of additives in water and feed on average daily feed consumption, daily weight gain, feed conversion ratio and daily water consumption was not significant in the whole period. Since the amount of water consumed by the chickens did not change, it can be concluded that the additives added to the water in the examined amounts do not have a spicy or unpleasant taste that would cause the birds to refuse to drink water. The relative length of duodenum, jejunum, cecum and colon was not affected by experimental treatments. However, the relative length of the ileum was lower in the chickens that received Entex in the feed compared to the control group. No significant difference was observed in the relative length of different parts of the intestine in the treatments that received herbal additives either in feed or water. The relative length of duodenum, jejunum, cecum, and colon, villus length, villus area, crypt depth, thickness of lamina propria, thickness of muscular layer, and thickness of advantis layer were not affected by experimental treatments. The chickens that consumed 500 mg/kg of Entex herbal additive of feed had a lower villus width in the ileum region compared to the control group chickens. The population of Escherichia coli bacteria in the ileum of chickens that had received the addition of O.X. Plant and Entex in the feed decreased compared to the control group. The population of Escherichia coli bacteria in the Entex treatment in the feed was also reduced compared to the Coxan treatment in the feed. The population of Lactobacillus bacteria in the ileum of chickens that received Coxan in water, O.X. Plant in feed and water, and Entex in feed increased compared to the control group. There was no significant difference in the population of Escherichia coli and Lactobacillus bacteria in the treatments that received herbal additives either in feed or in water. The use of plant essential oils in poultry feed, while improving the microbial population by increasing the number of lactobacilli, by improving the morphological characteristics of the intestine, probably improves the ability of digestion and absorption in the digestive system and improves the growth efficiency of broiler chickens. Antibody levels against SRBC were higher at 28, 35, and 42 days in all chickens consuming herbal additives in water. The performance of animals is significantly influenced by the state of health and safety of the animal. A weak or stressed immune system causes weight loss when dealing with infectious diseases, so the use of immune system stimulating substances can increase performance by improving the immune status. In raising poultry, it is important to strengthen the immune system to prevent the occurrence of diseases.
The results of this research showed that the commercial plant additives of Coxan, O.X. Plant, and Entex had no significant effect on growth performance, relative length and intestinal morphology. The population of opportunistic bacteria Escherichia coli was significantly reduced compared to the control group with the addition of O.X. Plant and Entex in the diet. In general, it can be concluded that adding tested herbal additives not only did not have a negative effect on the drinking water consumption of broiler chickens, but also using them in water improved the immune responses of broilers more than adding them in feed. A total of 336 Ross 308 broilers were examined in a completely randomized design with 7 treatments, 4 replications, and 12 chickens per replication. Experimental treatments included: control (without phytogenic in feed or water), Coxan in feed (300 mg/kg) and in water (200 mL/1000 L), O.X. Plant in feed (200 mg/kg) and in water (135 mL/1000 L) and Entex in feed (500 mg/kg) and water (350 mL/1000 L). Daily weight gain, daily feed intake, daily water intake and feed conversion ratio were measured. At 42 days of age, 2 birds were selected from each experimental unit and after slaughter, the length of the intestinal components was measured separately (duodenum, jejunum, ileum). In order to determine the microbial population, samples were taken from the ileum of chickens. EMB culture medium was used to determine Escherichia coli population and MRS culture medium was used for Lactobacillus bacteria. To check the humoral immune response, 0.1 ml of 25% sheep red blood cell solution in PBS was injected into the breast muscle of chickens on the 12th and 29th days of rearing. Blood was taken from the chickens on the 28th, 35th and 42nd days of breeding and the levels of Anti-SRBC, immunoglobulin G and M were calculated. Antibody titer against Newcastle disease was measured by HI method. The effect of additives in water and feed on average daily feed consumption, daily weight gain, feed conversion ratio and daily water consumption was not significant in the whole period. Since the amount of water consumed by the chickens did not change, it can be concluded that the additives added to the water in the examined amounts do not have a spicy or unpleasant taste that would cause the birds to refuse to drink water. The relative length of duodenum, jejunum, cecum and colon was not affected by experimental treatments. However, the relative length of the ileum was lower in the chickens that received Entex in the feed compared to the control group. No significant difference was observed in the relative length of different parts of the intestine in the treatments that received herbal additives either in feed or water. The relative length of duodenum, jejunum, cecum, and colon, villus length, villus area, crypt depth, thickness of lamina propria, thickness of muscular layer, thickness of advantis layer were not affected by the experimental treatments. The chickens that consumed 500 mg/kg of Entex herbal additive of feed had a lower villus width in the ileum region compared to the control group chickens. The population of Escherichia coli bacteria in the ileum of chickens that had received the addition of O.X. Plant and Entex in the feed decreased compared to the control group. The population of Escherichia coli bacteria in the Entex treatment in the feed was also reduced compared to the Coxan treatment in the feed. The population of Lactobacillus bacteria in the ileum of chickens that received Coxan in water, O.X. Plant in feed and water and Entex in feed increased compared to the control group. There was no significant difference in the population of Escherichia coli and Lactobacillus bacteria in the treatments that received herbal additives either in feed or in water. The use of plant essential oils in poultry feed, while improving the microbial population by increasing the number of lactobacilli, by improving the morphological characteristics of the intestine, probably improves the ability of digestion and absorption in the digestive system and improves the growth efficiency of broiler chickens. Antibody levels against SRBC were higher at 28, 35 and 42 days in all chickens consuming herbal additives in water. The performance of animals is significantly influenced by the state of health and safety of the animal. A weak or stressed immune system causes weight loss when dealing with infectious diseases, so the use of immune system stimulating substances can increase performance by improving the immune status. In raising poultry, it is important to strengthen the immune system to prevent the occurrence of diseases. The results of this research showed that the commercial plant additives Coxan, O.X. Plant and Entex had no significant effect on growth performance, relative length and intestinal morphology. The population of opportunistic bacteria Escherichia coli was significantly reduced compared to the control group with the addition of O.X. Plant and Entex in the diet. In general, it can be concluded that adding tested herbal additives not only does not have a negative effect on the drinking water consumption of broiler chickens, but using them in water improves the immune responses of broilers more than adding them in feed.

This study was conducted to investigate the effect of molasses kombucha on performance, intestinal morphology and intestinal microbial population on 320 Ross male broiler chickens in a completely randomized design in 5 treatments and 4 replicate with 16 chickens in each replicate, in the starter (1-10 days old), growth (11-24), the final (25-42) and whole period (1-42). Experimental treatments include drinking water containing: 1) tap water with no kombucha, 2) 0.015 and 0.003 kombucha, respectively, during the starter and growth period, 3) 0.015, 0.003 kombucha and 0.003 three days a week, respectively during the starter, growth and finisher period 4) 0.015 Kombucha during starter and 0.003 kombucha three days a week during growth and finisher period 5) 0.015 Kombucha during starter and growth period and 0.003 kombucha three days a week during finisher. All experimental treatments had a higher body weight gain than the control group (P < 0.05). During the starter and whole periods, except for treatment 2, addition of molasses kombucha significantly improved the feed conversion ratio (P<0.05). There was a significant increase in the villus surface area of the treatments compared to the control group (P<0.05). Molasses kombucha caused a significant increase in the Lactobacillus population and decreased the total coliforms in the cecum environment (P<0.05). In conclusion, 0.015 Kombucha during starter and growth period and 0.003 kombucha three days a week during finisher can improve the performance of broiler chickens.

Lipids (fat and oil) are the most concentrated sources of energy for animals, which are usually added to poultry diets to meet energy requirements for better performance (Abudabos 2014). However, there are problems with dietary lipid levels and digestibility in poultry, especially in young birds due to low bile secretion (Ravindran et al 2016). This physiological limitation of the poultry digestive system can be solved by using exogenous emulsifiers. Emulsifier can help increase the active level of lipids, stimulate the formation of micelles, and then increase the digestibility of dietary lipids and other nutrients in broilers (Siyal et al 2017). Upadhaya et al (2017) showed that 1, 3-diacylglycerol as an exogenous emulsifier can improve growth performance and increase nutrient digestibility in broilers. In addition, a large number of studies have also shown that exogenous emulsifier can improve meat quality and regulate fat metabolism of broilers (Zhao and Kim 2017). Bile acids are the main pathway of cholesterol catabolism in mammals. Cholesterol is converted into bile acids by changes in ring structure, oxidation and side chain shortening (Li and Chiang 2019). The chemistry of bile acids is complex due to the large variety of chemical structures in natural compounds such as cholic acid, kenodeoxycholic acid, deoxycholic acid, and lithocholic acid. Bile acids of birds are mainly composed of kenodeoxycholic acid and cholic acid (Hoffman and Hagee 2018). Recently, bile acids have been considered as an emulsifier to increase digestibility (Upadhaya et al 2019) and improve the performance of broiler chickens (Parsai et al 2007). Supplementation of bile acids in the diet of broilers significantly improves fat digestibility (Lammasak et al 2019). The effect of bile salts on performance, carcass characteristics and blood parameters of broiler chickens were investaigeted.

Three hundered one-day-old broilers (Ross 308) were divided into 5 treatments and 6 replications with 10 birds in each replication. Five experimental treatments included the control diet (corn soybean based diet), emulsifier (added to control diet) and three levels of 0.05%, 0.1% and 0.2% of poultry bile salts (added to control diet). All the dietary treatment were fed to the birds from day one to day 42 of age. The experiment lasted for 42 days and were performed during the starter (1-10 days), grower (11-24 days) and finisher (25-42 days). Performnce indices were measured during the difeferned periods and carcass characteristics and blood parameters were determined on day 42 of age. The data obtained from the present study were statistically analyzed using SAS statistical software and GLM procedure. To compare the means, Tukey's test was used.

The results showed that consumption of different levels of bile salts had no significant effect on feed consumption (P<0.05). However, consumption of 0.1% bile salts improved body weight gain and feed conversion ratio during the starter period (P<0.05). Previous studies have shown that the consumption of 0.05% commercial emulsifier can improve the growth performance of broiler chickens (Wang et al 2016). In addition, in the present study, 0.05% poultry bile acids supplement significantly improved daily weight gain and feed conversion ratio during 1 to 10 days, which is consistent with the results of Alzawqari et al (2011) regarding bile. These researchers observed improvement in daily weight gain with 0.05% bovine bile acid supplementation. Arshad et al (2020) reported that feed intake was not affected by bile acid supplementation in the initial, growth, finisher and overall periods. In the newly hatched chick, the ability to digest and absorb dietary fat is poor as a result of limited bile secretion (Tancharonrat et al 2013). For this reason, artificial bile acid and bile salts have shown the greatest effect in young broiler chickens to improve fat digestion, and the improvement in the performance of birds receiving bile in the initial period of recent research was for this reason. The results of Maisonnier et al (2016) showed that 0.5% of pig bile acids can increase fat digestibility and body weight in broilers. These results may imply that the supplementation of bile acids in diets improved the growth performance of broiler chickens by increasing the solubility and digestibility of dietary fat and fat-soluble nutrients in this study. Abdominal fat decreased significantly by consumption of 0.1% bile salts (P<0.05). Subcutaneous fat and abdominal fat are considered as the main factors influencing the performance of poultry carcasses (Tůmová and Teimouri 2010). In agreement with our results, many researchers have pointed out the positive effects of emulsifier on reducing fat status and improving carcass quality in broiler chickens (Zhao and Kim 2017). Blood triglyceride concentration was decreased in 0.05% bile salts fed birds wherease cholesterol and uric acid concentrations decreased in the birds fed emulsifier (P<0.05). Triglyceride, cholesterol, HDL and LDL blood are key indicators of lipid metabolism balance (Helkin et al 2017). In agreement with our results, researchers reported that bile acids increased hepatic AST and ALT activity in broilers and reduced serum triglyceride levels, which could be due to the participation of these enzymes in the lipogenesis process (Ge et al 2019). In addition, Siyal et al (2017) showed that feed emulsifier can reduce serum triglyceride concentration in broilers. It can also be stated that bile acids may enhance fat catabolism and inhibit fat synthesis by regulating the expression of genes related to lipid metabolism which may play a pivotal role in improving serum lipid profile and reducing fat deposition in broiler chickens (Ge et al 2019).

Totally, it was found that dietary bile salts supplementation improves the performance of, carcass characteristics and blood lipids in broiler chcikens.

Heat stress is one of the serious issue in poultry industry which causes significant economic losses. Decreasing feed consumption, increasing excretion and decreasing the bioavailability of nutrients during heat stress reduces the performance and immune response. Selenium is an essential trace element for humans and animals that plays a role in improving the antioxidant status and the immune system and inflammatory response. The goal of this study was to investigate the effects of different selenium sources [2-hydroxy-4- methyl seleno butanoic acid, selenomethionine and sodium selenite) on performance, carcass characteristics, antioxidant and immune response and blood characteristics in broiler under heat stress condition.

This experiment was conducted in a completely random designs with 240 Arbor Acres (Male) broilers chicks. Chicks were randomly distributed in 4 treatments and 6 replicates (10 chicks in each replicate). The experimental treatments include that: (1) basal diet + 0.3 mg 2-hydroxy-4- methyl seleno butanoic acid; (2) basal diet + 0.3 mg selenomethionine per kilogram of diet; (3) basal diet + 0.3 mg sodium selenite per kilogram of diet; (4) The basal diet that did not have any additives. The birds were kept at 32-340C (10.00 to 16.00; for 6 hours) from 22 to 42 days.

The results of this experiment showed that feed intake, body weight gains and feed conservation ratio were not affected by the experimental diets. The use of different sources of selenium had no significant effect on blood biochemical factors in broiler chickens under heat stress. dding selenium source with 0.3 mg/kg 2-hydroxy-4- methyl seleno butanoic acid significantly affected immunoglobulin G in comparison to other treatments. Diets containing selenium sources significantly increased the relative weight of the spleen compared to the control treatment (P < 0.05). The treatments of 2-hydroxy-4- methyl seleno butanoic acid and selenomethionine significantly decreased liver weight percent. The concentration of glutathione peroxidase, superoxide dismutase and catalase enzymes in blood were significantly increased by selenium sources in different treatments.

The use of selenium source improved the immune system and blood antioxidant status in broiler chickens.

Silver nanoparticles are one of the new achievements in nanotechnology, which are used in medicine, veterinary medicine, agriculture, and pharmaceuticals due to their antimicrobial activity. Silver nanoparticles can react with biological macromolecules and induce apoptosis by disrupting intracellular homeostasis. Hence, the aim of this study was to the effect of zeolite, organic acid and silver nanoparticles coated on zeolite on the expression of BAX and Bcl2 apoptosis genes in broiler chickens.

The number of 450 one-day- old broiler chicks (Cobb 500) were used in five treatments and six repetitions with 15 chicks per replicate in the form of a completely random design. Experimental diets were: control or basal diet (1), a basal diet supplemented by 1% zeolite (2), a basal diet supplemented by 1% zeolite coated with 0.5% nanosilver (3), a basal diet supplemented by 0.15% organic acid (4) and a basal diet supplemented by 1% zeolite coated with 0.5% nanosilver and 0.15% organic (5). The experiment was conducted with broiler chicken from 1 to 42 days old. The expression of the BCL2 and BAX apoptosis genes, liver sampling was done on the 21st and 42nd days of the breeding period.

The results of this experiment showed that in broiler chicks receiving zeolite treatment (Z) on d 21 and silver nanoparticles coated on zeolite treatment (NS) on d 42 of the breeding period the expression level of Bcl2 gene in liver tissue was significantly increased (P<0.05) compared to the control treatment (C Also, the expression of the BAX gene in the liver tissue in NS and NSOA treatments on d 42 of the breeding period increased significantly compared to the control treatment (P<0.05).

In conclusion, the results of this experiment showed that zeolite and NS and NSOA treatments have an increasing effect on the expression of Bcl2 and BAX genes, while this effect was not observed in organic acid treatment.

Many studies have been conducted to determine proper corn particle sizes for mash or pelleted diets in broiler chicken’s nutrition, aiming not only to achieve optimum production goals such as higher weight gain and minimum feed conversion ratio but also to reduce milling energy expenditures. However, pelleted and crumbled feed forms are mainly used in intensive poultry production systems in many countries, and mash feed is primarily common in less intensive production systems. Mash feed is less costly and puts less pressure on birds’ metabolic systems to achieve their optimum biological growth potential, which may result in higher welfare and lower metabolic disorders. Therefore, the purpose of this study was to investigate the effects of different proportions of fine and coarse ground corn (3- and 6-mm sieve opening hole size, respectively) on performance, the relative weight of gastrointestinal organs (%), and intestinal morphology in male broiler chickens.
A total of 576 1-day-old male Ross 308 broiler chicks were purchased from a commercial hatchery and raised from 1 to 42 days of age. All birds received identical basal diets from 1 to 11 days of age, but different experimental diets from 12 to 42 d. Experimental diets (12 to 42 days of age) consisted of six corn mixtures prepared by combining different proportions (w/w) of corn ground through sieves with either hole sizes of 3 or 6 mm as 100:0; 80:20; 60:40; 40:60; 20:80 and 0:100 percentage, respectively. The particle size characteristics including geometric mean diameter (GMD) and geometric standard deviation (GSD) of ground corn and finished feed samples were determined. Birds’ body weight was recorded at 12, 24, and 42 days of age as a group basis for the calculation of birds’ bodyweight gain (BWG) during the grower (12-24 d) and finisher (25-42d) periods. The birds’ feed intakes (FI) were also measured during the same period to calculate the feed conversion ratio (FCR) after adjustments were made for the body weights of dead birds, which were recorded daily. on the 21st day of the experiment, two birds from each pen were selected and killed via cervical dislocation. The liver, gizzard, small intestine, caecum, and pancreas of the sampled birds were carefully removed from their abdominal cavity, their weights were recorded carefully, and the relative weights of these parts to the live body weights were calculated and expressed as the percentage of birds live weights. Gizzard acidity was measured on the 21st day of the experiment. Parts from the middle of the jejunum and ileum of slaughtered birds (21 d) were excised and flushed gently with saline solution and immediately placed in a 10% formalin solution. Villus height, villus width, and crypt depth were measured in the laboratory.
Results showed that feeding mash diets with different particle sizes (~775, 835, 910, 1000, 1060, and 1150 µm) had no significant effects on birds’ BWG, FI, and FCR during different growth periods. However, the orthogonal polynomial contrast test showed that the changing of feed particle size from fine (~775 µm) to coarser particles by combining different portions of corn ground with a sieve hole size of 3 mm (~775 µm) and 6 mm (~1150 µm) had linearly deteriorated BWG and FCR from 12 to 24 days of age. The birds’ mortality rate (%) was not influenced by average feed particle size from 12 to 42 days of age. The negative influence of very coarse particle size from 12 to 24 days of age (>1000 µm) in the current experiment is an indicator of birds’ gastrointestinal limits in dealing with coarse particles. The coarse grain particles increase the energy required for the growth and maintenance of the gizzard. The results of the current experiment showed that feed particle size did not significantly affect the relative weights of gastrointestinal sections to body weight at 21 d (P>0.05). However, the relative weight of gizzard to live body weight at 21 d significantly (P<0.001) increased in birds fed diets with higher average particle size (≥775 µm). The results of the orthogonal polynomial contrast test showed that the relative weight of gizzard to live body weight at 21 days of age linearly (P<0.0001) increased by changing the feed particle size from fine to coarser particles. Coarse particles increased the digesta content in the gizzard, which stimulates the development of the gizzard. In addition, the findings of the current experiment indicated that ileum and jejunum morphometry traits such as villus height, crypt depth, villus height to crypt depth, villus tips, and base widths were not influenced by changing the average feed particle size. The pH of gizzard content at 21 days of age was not influenced by the feed particle size.
Feed particle size of 775 to 1150 µm in a corn-based mash diet had no significant effect on performance traits or small intestine morphology traits. However, high coarse diets had the potential to deteriorate BWG and FCR at earlier stages of the growth period.

This experiment was conducted to study the effect of using beef spleen meal on growth performance and safety of broilers on 120 one-day-old male Ross 308 broiler chicks in a completely randomized design with 5 treatments, 4 replicates, and 6 chicks per replicate. The experimental included different levels of 0, 2, 4, 6, and 8% spleen meals. Feed intake, weight gain, and feed conversion ratio were recorded periodically. At the end of the experiment, two chickens each replicate were slaughtered to determine carcass components. To evaluate the immune response, a Solution of sheep red blood cells (SRBC) was injected intravenously. The amount of dry matter, crude protein, ether extract, calcium, phosphorus, sodium, potassium, iron, copper and zinc content of samples were; 95, 77.3, 12.5, 0.038, 1.09, 0.51, 0.36, 0.23, 0.0012 and 0.0078%. The result showed that most performance parameters were significantly affected by the different levels of spleen meal so using spleen meal caused more weight gain than the control group. Diets containing spleen meal had significantly lower feed consumption and feed conversion ratio than the control group (p≤0.001). The use of different levels of spleen meal had no significant effect on the safety parameters measured in this experiment. According to the obtained results, the use of spleen powder in the broiler diet is recommended up to 8% nutritionally and economically.

Organic acids are compounds that can be considered as a replacement for antibiotics. Butyric acid is known as the main stimulant of intestinal wall tissue and modulator of normal intestinal microflora (Van Immerseel et al. 2004). Butyric acid is also the main source of energy for intestinal cells and is essential for the development of gastrointestinal-related lymphoid tissue (Friedman and Bar-shira, 2005). The positive and beneficial effect of butyric acid on the functional traits of broilers has been reported (Leeson et al. 2005; Antongiovanni et al. 2007). Butyric acid is a highly volatile and highly smelling compound, much of which is absorbed at the beginning of the gastrointestinal tract (Bolton and Dewar, 1965). The effects of butyric acid appear to improve if it is protected from absorption in the upper gastrointestinal tract (Leeson et al. 2005). For this purpose, butyric acid glyceride along with butyrate-calcium was used in this study. Calcium butyrate is a protected form of butyric acid that is produced using a new technology by Kimia Daroo Mehr Company in Tehran, Iran. This product passes intact through the gut and after decomposition by the pancreatic lipase is absorbed in all different parts of the intestine. Calcium butyrate is a bio-odorless substance and contains 70% butyric acid. butyric acid glyceride (C4) is the brand name of butyroglycerol (Sanadam Pars, Tehran, Iran). Butyric acid is esterified with a glycerol molecule and the resulting compound has a very stable structure. After consumption by animal, pancreatic lipase, it is broken down to the constituents and is absorbed. The aim of this experiment was to investigate the effects of different dietary supplementation levels of calcium butyrate, butyric acid glyceride and their mix on growth performance, carcass traits and jejunal morphology in broiler chickens. A total of 400 one-d-old broilers from Ross 308 strain were allotted to 10 dietary treatments, 5 replicates and 10 broiler chicks per each, from 1 to 42 days of age. Experimental diets included: control (without additives), and supplementation of calcium butyrate (0.15, 0.30 and 0.45% of diet), butyric acid glyceride (C4) powder (0.15, 0.30 and 0.45% of diet), and three levels of calcium butyrate and C4 powder mixture in equal proportion (0.075+0.075, 0.15+0.15, and 0.225+0.225% of diet). Light was provided as 23 h light and 3 h darkness. Rearing house temperature was set at 32°C on day one, and then decreased by 3°C per weak to reach 21±2 °C and remained constant until the end of the experiment. During the experimental period, feed and water were provided ad libitum. Mortality were collected, weighed and recorded daily. At the end of each period, the amount of feed consumed and the group weight of the chickens in each pen were recorded and feed conversion ratio was calculated after adjusting for dead birds. In order to evaluate the morphology of the small intestine at the age of 24 days, one chick per pen close to average pen weight was selected and slaughtered. About one centimeter was removed from the middle part of the jejunm tissue and placed in 10% formalin solution and sent to the laboratory. At the end of the rearing period (42 days), after weighing the chickens, one chick was selected from each replication and slaughtered to measure carcass traits. Data were analyzed in a completely randomized design using General Linear Model procedure by SAS (2009) statistical software. The treatments mean was compared using Duncan's multiple range test at P < 5 %. The average body weight of chicks at the age of 10 days and the mean daily weight gain of 1-10 days in the groups receiving the mixed powder C4 and calcium butyrate (0.225+0.225% of diet) was significantly higher than the control group (P< 0.05). However, the effect of experimental treatments on body weight at 24,42 days of age, and the weight gain at 11-24, 25-4, and 42-1 days of age was not significant (P> 0.05). The feed conversion ratio (FCR) at the age of 1-10 and 1-42 days in control treatment was significantly higher than other treatments (P <0.05). Treatment with mixed powder c4 and calcium butyrate (0.225+0.225% of diet) had the highest relative hepatic weight and lowest abdominal fat weight compared to other treatments (P<0.05). Regarding to the morphological traits of the small intestine, the highest thickness of the muscle layer was observed in the control treatment (P<0.05). Iincreasing villus length can be attributed to the reduction of pathogenic bacteria. Increasing the length of villus increases the digestibility and absorption capacity of nutrients, and since this increase in jujumen, which is the main source of digestion and absorption of nutrients in birds, can be concluded that it is likely the use of organic acids can have beneficial effects on the digestion and absorption of food and subsequently the performance of the birds. In this study the thickness of the muscle layer in the treatment of organic acid intake was reduced, it can be concluded that the use of organic acid supplementation with the effects on the pH gastrointestinal tract probably reduced the pathogenic bacteria in the intestine. By reducing the number of pathogenic bacteria in the intestine and making it healthier, it requires a thinner epithelium to protect the surface of the intestine, which is likely to result in a thickening of the muscle layer thinner. Given that most of the additives that have been introduced as growth promoters have been shown to have an impact on the performance of broiler chickens due to antimicrobial activity and the effect on the microbial flora of the digestive tract. Therefore, breeding conditions and the rate of infection of birds with pathogenic bacteria in the test can be as a result of the test. Each of these additives has different levels of compounds and levels, the dosage and the ingredients used in the experiment can also be effective in the various results obtained from using these growth stimulating agents. In general, the results of this experiment showed that the addition of butyrate-calcium and glyceryl butyric acid to the diet alone or combined with each other, with a positive effect on digestion and absorption of nutrients, could improve the growth performance, some carcasses components and Morphology of small intestine of broiler chicks. The difference in the results of the research may be related to the different buffering capacity of the experimental diets or the type and amount of organic acids used in the experiments.

In order to investigate the effect of inorganic selenium replacement with organic selenium from Spirulina algae on performance and breast meat quality of broilers, a total of 160 one-day-old chicks were used in a completely randomized design with four treatments, eight replicates and five birds per each replicate. The sources of selenium used included sodium selenite and organic selenium from Spirulina algae which were replaced at two levels of 50 and 100 percent. The organic selenium was produced by the culture of Spirulina algae and its enrichment with selenium. The selenium content of different treatments was measured by ICP-Mass method. In this experiment, the feed intake and body weight gain parameters were measured weekly and feed conversion ratio was calculated. At 42 day of age, one bird was slaughtered from each replicate and the weight of carcass ready to cook was measured. The breast meat was sampled for measurement of pH and selenium storage. The results showed that it was not observed any significant difference in performance traits and ready to cook carcass percentage among different treatments. There was no significant difference in breast muscle pH at 0 and 24 hours after slaughtering. The amount of selenium deposited in breast muscle of birds fed organic selenium had significant increase when compared with other treatments (P<0.05). Generally, the results of this study showed that 100% replacement of sodium selenite with organic selenium from Spirulina algae led to increase in breast muscle selenium deposition without reduction in bird performance.

By increasing the poultry and broiler production industry, concerns for  having a food free of pathogens, and as a result, producing a quality and healthy product are increasing. Therefore, correct and efficient disinfection of poultry diets with maintaining the quality of them is very important. The aim of this study was to investigate the effect of gasification of complete poultry feed by ozone on microbial papulation and the quality of broilers diets.

From 432 commercial male Ross strains in a 2 × 2 factorial experiment with three levels of ozone gas (zero, 20 and 30 ppm) and two levels of low fat (1.5 and 2% vegetable oil for growth and finishing periods respectively) and high fat (3 and 4% of vegetable oil for growth and finishing periods, respectively) were used in a completely randomized design with 6 treatments and 4 replications. Diets were ozonated for 120 minutes at concentrations of 20 and 30 ppm. Aflatoxin B1 levels, microbial papulation and the presence of fungi in the feed as well as oxidation of feed lipids in broiler chickens were assayed  after ozonation.

Aflatoxin B1 was not found in grower and finishe diets. The lipid oxidation in ozonated diets with 30 ppm was significantly higher than non-ozonated diets (P<0.05).

According to the results of this experiment, the use of ozone gas to disinfect the broiler chickens diets, despite the destruction and inactivation of microbes and fungi, increases the oxidation of dietary fats.

This experiment was designed to investigate the effects of sunflower seed meal fermented with Aspergillus niger and the probiotic Saccharomyces cerevisiae on the morphology and microbial population of different parts of the intestine and some digestive parameters.

This experiment conducted as a completely randomized design with 200 one-day-old Ross 308 male commercial broiler chicks, in five treatments five replications and eight chickens per replication. Experimental treatments including: 1- Diet containing sunflower meal fermented with Aspergillus niger 2. Diet containing sunflower meal fermented with Saccharomyces cerevisiae 3- Diet containing sunflower meal fermented by both Aspergillus niger and Saccharomyces cerevisiae 4. Diet containing unprocessed sunflower meal 5- Control diet based on corn and soybean. The effect of treatments at the end of the 39-day raising period was investigated on the morphology of ileum, viscosity, microbial population and pH contents of broiler chick’s intestine.

Intestinal morphological results showed that the highest villus height and the ratio of villus height to crypt depth in ileum were related to birds fed fermented treatment with Aspergillus niger (p<0.05). The amount of viscosity in the jejunum and ileum of the small intestine in all three treatments contained fermented sunflower meal was higher than the treatment contained unprocessed sunflower meal (p<0.05). The treatment contained sunflower meal fermented with Aspergillus niger was the closest to the control treatment based on corn and soybean (p<0.05). The population of duodenum coliform increased significantly in the treatment contained sunflower meal fermented by Aspergillus niger (5.41) and also the treatment contained sunflower meal fermented by both fungi and yeast (5.35) compared to the control treatment (5.57). The highest population of aerobic bacteria in this section was related to the treatment contained sunflower meal fermented by Saccharomyces cerevisiae (5.45): (p<0.05). The highest populations of Lactobacillus and aerobic bacteria in the jejunum were related to the treatment contained sunflower meal fermented with Aspergillus niger (5.16) and the control treatment based on corn and soybean (6.49): (p<0.05). The highest population of Lactobacillus bacteria in the ileum was related to treatment contained sunflower meal fermented with Aspergillus niger (5.92) and treatment contained unprocessed sunflower meal (5.95): (p<0.05). Also, the highest population of coliform (5.43) and aerobic bacteria (7.61) in this part was related to the treatment containing sunflower meal fermented with Aspergillus niger (p<0.05). The population of coliform, lactobacillus and aerobic bacteria in cecum was higher in all treatments than the control treatment based on corn and soybean (p <0.05). The highest pH of duodenum and jejunum was related to control treatment based on corn and soybean (p<0.05).

The results of this experiment indicated that fermented sunflower meal with Aspergillus niger and Saccharomyces cerevisiae decreases the pH of the gastrointestinal tract contents, increases the total microbial population, decreases coliform and increases Lactobacillus and improves the intestinal morphology of broiler chicks.

Application of growth-promoting antibiotics in poultry nutrition improves growth, feed intake, feed conversion ratio and reduces mortality. But, due to their persistent effects and increased drug resistance to pathogenic bacteria and the transmission of bacteria to humans through the food chain, the European Union banned their use. One of the natural alternatives is medicinal plants. Because plant products for reasons such as availability, ease of use, reduction of side effects, antibacterial and antioxidant properties, were used to treat some diseases in humans and animals. Among these medicinal plants we can mention yarrow with the scientific name of Achillea millefolium. This plant in addition to high antimicrobial and antioxidant properties; has antifungal properties, stimulates appetite, improves digestion and feed intake, improves the condition of the gastrointestinal tract, etc. This plant also accelerates digestion and shortens the passage of food through the gastrointestinal tract by increasing bile production and enzymatic activity. On the other hand, probiotics are living microorganisms of a nonpathogenic and nontoxic in nature that improve gastrointestinal health and improve performance in birds by improving intestinal microbial balance. According to these cases, this study was performed to evaluate the effect of yarrow essential oil in comparison with a growth-promoting antibiotic and probiotic on performance of broiler chickens. A total of 200 day-old male broiler chicks (Ross 308) were studied in a completely randomized design with five treatments, and four replicates. Experimental diets were: 1) basal diet (control), 2 and 3) basal diets supplemented with 100 and 200 mg/kg of yarrow essential oil, respectively, 4) basal diet supplemented with 200 mg/kg probiotic, and 5) basal diet supplemented with 500 mg/kg antibiotic (flavophospholipol). Body weight and feed intake were measured at the end of each growing period and were used to calculate Performance parameters such as body weight gain, and feed conversion ratio. At the end of the experiment, one bird per each replicate was slaughtered for meat quality tests, including measurements of TBARS, pH, water holding capacity, dripping loss and antibody titer. For TBARS, the amount of fat oxidation of the sample was measured by measuring the amount of malondialdehyde and the microtiter hemagglutination method was used to determine the antibody titer produced against sheep erythrocytes. During the whole experimental period, birds received yarrow essential oil at 100 mg/kg diet, showed significantly higher body weight and lower FCR compared to the control group(P <0.05).  The lowest feed intake was observed in birds that were fed from the level of 200 mg/kg of yarrow essential oil. However, this effect was significant only in comparison with antibiotic treatment, which showed the highest feed intake (P <0.05). Different results have been reported in this regard which can be related to the type of plant, the amount of active ingredients, the level of the medicinal plant used and the interactions with other components of the diet. The TBARS index, indicating lipid oxidation of meat, in chickens fed with different levels of yarrow essential oil and probiotic were lower compared to the control group and antibiotics. In vitro, researchers have shown that plant essential oils, such as yarrow alkaloids, can reduce free radicals and can be a good alternative to synthetic antioxidants. Also in the study of using a mixture of plant extracts increased the concentration of phenols and decreased the amount of TBARS in the meat of broilers. pH, water holding capacity, dripping loss and cooking loss were not affected by the dietary treatments. The antibody titer against sheep red blood cell (SRBC) was lower in the control group in compare to those fed different levels of yarrow essential oil. In some studies, yarrow has increased humoral immunity with its antimicrobial and antioxidant properties; but, the amount used and the concentration of plant material were also effective. Based on the results, the use of 100 mg/kg yarrow essential oil increased body weight, improved feed conversion ratio and also increased antibody titer at 42 days of age. On the other hand, the TBARS index in chickens fed with different levels of yarrow essential oil was lower in compare to control group. Finally, according to the results, it can be concluded that the use of yarrow essential oil at the level of 100 mg/kg can be a good substitute to antibiotics in poultry nutrition.

Lactic acidosis occurs as a result of hypoxia and rapid growth of broilers and can be considered as a physiological stress. In two experiments, the effect of extra nutritional levels of vitamin D3 and guanidinoacetic acid was investigated on performance, relative weight of organs, some physiological and behavioral parameters of broiler chicks under lactic acidosis stress.

In both experiments, 144 chickens of Ross 308 strain were used to study the effect of subcutaneous injection of vitamin D3 at 0 (negative and positive controls), 20,000, 30,000, 40,000 and 50,000 international unit and dietary levels of GAA at 0, 0.6, 1.2, 1.8, 2.4 and 3 g/kg in a randomized complete block design with 6 treatments, 4 replications and 6 birds per replication.

In the first experiment, liver fat concentrations in birds receiving 50,000 IU of vitamin D3 were 21.79% and 19.16% lower, respectively, compared to negative control and birds receiving 30,000 IU of vitamin D3 (p<0.05). In Experiment 2, the survival rate of birds receiving 1.8 and 3 g/kg GAA in the diet was greater than the birds receiving 0.6 and 1.2 g/kg GAA (p<0.05). Behavioral parameters of the birds were affected by vitamin D3 injection as well as GAA dietary levels (p<0.05).

The results show that subcutaneous injection of vitamin D3 at the level of 50,000 IU and adding GAA to diet at the level of 1.8 g/kg has positive effects on modulation of physiological stress caused by lactic acidosis in broilers.