BACKGROUND: Reducing the protein and amino acid content of diet or altering the dietary electrolyte balance were suggested as the effective strategies to prevent the harmful effects of the heat stress in poultry.OBJECTIVES: This study surveyed the effects of various levels of threonine and dietary cation-anion balance on the broiler chickens under the heat stress conditions.METHODS: 700 one-day-old male broilers (Ross 308) were used for 6 weeks under high- temperature conditions. This experiment was conducted using a 2 × 3 + 1 factorial experiment based on a completely randomized design, with 7 treatments (5 replicates per treatment and 20 birds per replicate). Experimental factors included two threonine concentrations (recommended level and 10 % above recommended level) and three dietary electrolyte balances (175, 250, and 325 mEq/kg). The control group considered the treatment with a normal threonine concentration (recommended level) and a dietary electrolyte balance of 250 mEq/kg under optimal temperature conditions.RESULTS: Although there was no interaction between threonine level and electrolyte balance, the electrolyte balance of 175 meq/kg increased the performance index compared to the electrolyte balance of 250 or 325 mEq/kg (P<0.05). The villus height to crypt depth ratio and villus surface area in the jejunum improved with an electrolyte balance of 175 or 250 mEq/kg (P<0.05). A decrease in the dietary electrolyte balance increased in the nitrogen-corrected apparent metabolizable energy (P<0.05). Besides, an increase in the population of lactobacilli and bifidobacteria in the cecum, as well as an increase in protein digestibility, were observed by increasing levels of threonine in the diet (P<0.05).CONCLUSIONS: Based on these results, a high level of threonine or a low electrolyte balance in diet (175 mEq/kg) may improve the performance, metabolizable energy, and intestinal microbial flora of broilers reared under heat stress.

BACKGROUND: Stocking density is one of the most important problems in the poultry industry, which impair their production and welfare.OBJECTIVES: This experiment was done to evaluate the effect of organic selenium supplementation on the growth performance, blood metabolites, and the meat quality of broiler chickens in different stocking densities.METHODS: 216 one-day-old male broiler chickens (Ross 308) were used in 2×2 factorial arrangements by 2 stocking densities (7 and 15 birds/m2) and 2 levels of selenomethionine (0 and 0.4 mg/kg) in a completely randomized design with 4 treatments and 4 replicates.RESULTS: The feed intake (FI), and body weight gain (BWG) were significantly affected by the stocking density and selenomethionine (SE-MET) supplementation in the overall experiment (P<0.05). FI and BWG decreased and feed conversion ratio decreased in 15 bird’s density, while SE-MET inclusion improved these traits (P<0.05). Increasing stocking density increased the plasma glucose (P<0.05). Blood glutathione peroxidase and lymphocyte levels reduced at 15 bird’s density, while increased by 0.4 mg SE-MET supplementation (P<0.05). Increasing stocking density increased blood heterophil, while SE-MET inclusion decreased it (P<0.05). Meat pH and cooking loss were not affected by stocking density. Dripping loss (DL) increased, and water holding capacity (WHC) decreased at 15 bird’s density, but 0.4 mg SE-MET decreased DL and significantly increased WHC (P<0.05).CONCLUSIONS: It was concluded that increasing stocking density had the negative effects on the growth performance and meat quality of broiler chickens; however, the supplementation of 0.4 mg of SE-MET to diet can improve the growth performance, blood metabolites and meat quality of broiler chickens.

BACKGROUND: Blowfly (Lucilia sericata; Diptera: Calliphoridae) is an external parasites of domestic animals and the causative agent of myiasis, which is involved in the transmission of a  number of bacterial pathogens. Application of chemical insecticides is one of the most common methods for controlling this pest, which have recently been reported resistant populations of L. sericata to some insecticides. Therefore, identifying and recommending new and low-risk insecticides for humans and environment is of prime importance.OBJECTIVES: This research aimed to investigate the toxicity of insecticides deltamethrin, spinosad, pyridalyl, and pirimiphos-methyl on the third instar larvae of L. sericata.METHODS: In the present study, the bioassay tests were performed by immersion of larvae in concentrations of insecticides that caused 10 to 90% mortality of larvae, as a factorial experiment in a randomized complete block design. Additionally, the median lethal concentration (LC50)  was determined from the probit analysis of bioassay data for the studied insecticides.RESULTS: The results of analysis of variance and the comparison of the mean mortality (%) of third instar larvae were significant at the level of 1% probability. According to bioassay tests, the estimated LC50 values for deltamethrin, spinosad, pyridalyl, and pirimiphos-methyl were 186.49, 26.88, 85.08, and 134.97 mg L-1, respectively. Overall, the results revealed that spinosad and pyridalyl had the highest lethal effect on blowfly larvae while deltamethrin had less advers effects on this pest.CONCLUSIONS: Spinosad, as a relatively new insecticide, with very low toxicity towards mammals and other non-target organisms, showed the highest lethal effect on blowfly larvae and can be an appropriate alternative to older insecticides in controlling this pest.

BACKGROUND: Homocysteine (Hcy) is a sulfur-containing amino acid derived from methionine. Several studies have suggested that plasma Hcy may be a useful biomarker of cardiovascular disease in human. There is limited information about serum homocysteine in heart diseases of dogs.OBJECTIVES: The present study aimed to assess the concentration of serum total Hcy and evaluate the relationship between its concentrations and serum levels of cholesterol, triglycerides, and activities of creatine phosphokinase and aspartate aminotransferase in small breed of dogs with endocardiosis.METHODS: For this purpose, a total of 15 dogs (seven males and eight females) with acquired endocardiosis were confirmed by clinical examination, auscultation, thoracic radiography, and echocardiography. In addition, 15 normal dogs of the similar age, breed, and weight were selected as the controls. All the examinations performed on the patients were carried out on the healthy dogs. Homocysteine was measured via an enzymatic method. Additionally, the activities of CPK and AST and the levels of cholesterol and triglycerides were assessed utiling commercial kits. Subsequently, the data were analyzed with t- student test and one- way ANOVA and Pearson’s linear correlation test was used to determine the relationship between serum homocysteine levels with triglycerides, cholesterol, CPK, and AST.RESULTS: The results revealed no significant differences concerning serum homocysteine level and AST activity between the two groups; meanwhile, the increase in serum triglycerides and CPK activities in dogs with heart disease was statistically significant compared to that in the control group. However, there was no significant correlation between homocysteine and the other measured parameters.CONCLUSIONS: The present study indicated that the role of homocysteine as a new risk factor associated with dog endocardiosis is questionable and it seems as if in human studies related to homocysteine and heart disease, the selection of dog as animal model requires further investigation.

BACKGROUND: Oxidative stress is believed to be one of the major causes of tissue damage in aquatic animals exposed to heavy metals. It leads to certain changes in the antioxidant and enzyme system. Given the fact that research on the effect of sub-acute toxicity of silver nitrate in shrimps is not very developed, the present study can be conducive to formulating the international standards of contamination of shrimps with silver nitrate.OBJECTIVES: The present study aimed to evaluate the toxic effects of silver nitrate on the changes in the antioxidant and enzyme systems of hepatopancreas, muscle and gills of Litopenaeus vannamei.METHODS: After acclimatization of shrimps, they were exposed to silver nitrate with concentrations of 0.0084, 0.021, 0.042 and 0.063 mg/L for 21 days. At the end of the experimental period, gill, muscle and hepatopancreas were sampled, and the changes in the antioxidant system (SOD, GPx and GST) and metabolic enzymes (ALT, ALP, AST and LDH) were examined.RESULTS: There was no significant difference in terms of SOD and GST activity in the gill and muscle of the exposed shrimps (P>0.05). However, GPx in treatment 4 increased significantly in gill and muscle while it saw a decrease in hepatopancreas (P<0.05). In hepatopancreas, GST significantly increased in treatments 3 and 4 (P<0.05) whereas SOD did not show any significant changes compared with other treatments (P>0.05). The metabolic enzymes of the muscle did not show any significant differences in any of the treatments (P>0.05), but in gill, the level of ALT in treatment 4 decreased significantly while the levels of AST and LDH in treatment 3 and 4 significantly increased (P<0.05). In hepatopancreas, the activity of ALT in treatments 2 and 4, AST in treatments 3 and 4, and ALP in all treatment except treatment 1 saw significant reduction. Nevertheless, LDH in treatments 3 and 4 had a significant rise (P<0.05).CONCLUSIONS: A significant increase in GST and LDH as well as a significant decrease in GPx and ALT, AST and ALP enzymes in the hepatopancreas revealed that the antioxidant and enzyme system of shrimps is further disturbed with the rise in silver nitrate concentration in the hepatopancreas compared to the gill and muscle.

BACKGROUND: Meat is one of society's most important nutritional needs, the price of which is higher than other food groups. In recent years, the use of meat products has increased due to human lifestyle changes. Fraud in meat products occurs for various reasons, including the economic value of meat. Therefore, it is crucial to use fast and accurate methods of identifying these frauds.OBJECTIVES: The purpose of this study is to determine the unauthorized tissue by a histological method as well as to determine the unauthorized species used in meat products of factories in Hamadan province.METHODS: In the summer of 2021, fifty samples were collected from active production units of the Hamedan province that were available in the Hamadan city market and transferred to the laboratory for histological laboratory and animal species determination by PCR test. For the histology test based on the national standard 6103, the samples were subjected to fixation, passage (dehydration, clearing, impregnation with molten paraffin), blocking, sectioning, and H&amp;E staining. PCR method was used to determine the type of animal species used in the production of the collected samples.RESULTS: The results confirmed the presence of unauthorized tissues, including bone, cartilage (articular and respiratory cartilage), skin, and glandular organ in meat products. Also, PCR test results showed that chicken meat was found in 100% of the samples labeled with beef.CONCLUSIONS: The presence of illegal tissue and the use of chicken meat in products labeled as beef meat is evident in the sausages produced in Hamadan province.

BACKGROUND: Bovine Herpes Virus-1 (BHV-1) belongs to the  Alpha herpesviral family. The virus is the cause of Infectious Bovine Rhinotracheitis (IBR) and Bovine Abortion. In the initial infection, the virus proliferates excessively. Moreover, shedding the virus leads to conditions in the latent phase of the disease. Infectious Bovine Vulvovaginit (IPV ) is the genital form of the disease that represents a genital infection and transmits via pustules and mucopurulent secretions. Exposure to the virus in genital mucosa leads to IPV infection through mating or artificial insemination and the diseases that can be transmitted to healthy livestock by frozen sperm during artificial insemination.OBJECTIVES: Viral contamination of the semen is one of the routes to spread the disease among dairy cattle. Therefore, we investigated the presence of the virus in domestic and frozen imported semen consumed in industrial dairy cattle farms.METHODS: In the present study, 140 frozen straws were collected. After melting each straw, 200 µl of obtained semen was used for DNA extraction, which was done directly on the semen samples and via a Genome Extraction Kit. Subsequently, to ensure the accuracy of the extraction, the PCR technique was done using PRM-1 gene primer. Tracking the viral genome was done using the PCR technique and known primers.RESULTS: In total, one out of 140 samples was found to be virally contaminated, and IBR contamination was confirmed by repeating all the steps and determining the gene sequence.CONCLUSIONS: It is necessary to further investigate the possibility that contamination can be transmitted via frozen semen, given that even one out of 140 samples is contaminated, and the importance of the disease.

BACKGROUND: Stenotic nares and malocclusion are common congenital disorders in the brachycephalic breeds of cats which cause respiratory and oral problems in these breeds, respectively.OBJECTIVES: In this study, the prevalence of two congenital disorders, stenotic nares, and malocclusion, the correlation among them in brachycephalic breeds of cats referred to several private veterinary clinics in Tehran were evaluated.METHODS: 90 brachycephalic cats were evaluated for stenotic nares, and malocclusion and indices was checked, then determined the prevalence percentage and correlation with the statistical data between stenotic nares and malocclusion in brachycephalic breeds of cats were referred to several private veterinary clinics in Tehran.RESULTS: Malocclusion was diagnosed in 35 cats (38.9 %), stenotic nares were detected in 31 cats (34.4 %), and two diseases were diagnosed in 17 cats (18.9 %) concurrently in 90 brachycephalic cats. According to a statistical test, the probabilities of identifying the second disease are 2.7 times higher if one of the two disorders is identified.CONCLUSIONS: The prevalence of stenotic nares and malocclusion in brachycephalic cats is very high and there is a significant correlation between two disorders so clinicians should have great attention in their clinical examination of these two disorders in these breeds.