مجله تحقیقات دامپزشکی
سال هفتاد و هفتم شماره 2 (تابستان 1401)

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.

This study surveyed the effects of various levels of threonine and dietary cation-anion balance on the broiler chickens under the heat stress conditions.

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.

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).

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.

Stocking density is one of the most important problems in the poultry industry, which impair their production and welfare.

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.

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.

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).

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.

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.

This research aimed to investigate the toxicity of insecticides deltamethrin, spinosad, pyridalyl, and pirimiphos-methyl on the third instar larvae of L. sericata.

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.

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.

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.

Impingement of the dorsal spinous processes is a common cause of pain and poor performance in sport horses.

This study was performed to evaluate the prevalence of impingement in dorsal spinous processes and the correlation between the occurrence of this complication and certain parameters, such as age, height, weight, discipline, breed, neck length, and clinical signs.

In this study, radiographic examination of the spine of 50 horses were performed. The information about height, weight, discipline, breed, neck length, and clinical signs were also collected. Radiographic grading was based on the degree of the changes in inter spinous spaces and their densities (0-4 degrees). The clinical examinations were carried out to evaluate the pain in the spine. Statistical analysis was performed to investigate the correlation between the collected data.

The highest incidence of impingement was seen in the middle thoracic area. There was a significant correlation between the occurrence of impingement and age and the breed of the studied horses. There was no correlation between the incidence of impingement and sex, height, neck length, and weight of the studied horses.  Increased radiographic grade often leads to an increase in the severity of clinical signs. A higher grade of radiographic sign in each horse was indicative of more involved inter spinous spaces.

According to the results of this study, Grade 3 and 4 had high specificity with clinical signs; therefore, preparation of a radiograph of the spine before purchasing a horse could be highly recommended.

Brucellosis or Malta fever is one of the most prevalent zoonotic diseases considered as a health and economic concern.

The current study aimed to employ several methods to detect Brucella in blood and milk samples of saanen goat and use a safe and definitive method to diagnose this disease.

In this study, 122 blood samples and 122 milk samples were collected from saanen goats. After culture and serological-based isolation methods (RBPT, Wright, 2ME, and Ring test), DNA was extracted from all the blood and milk samples. PCR was carried out using B4 and B5 primers on all the extracted DNAs in order to detect the B. abortus and B. melitensis; PCR was carried out with Br.a and Br.m primers.

The results of all the blood samples were negative, but bacterial growth was observed in three milk samples, which was detected in biotyping, biovar 1 melitenensis. The PCR results for detection of Brucella spp. of nine blood samples and nine milk samples were positive. Using mPCR primers, B. melitensis were identified through all the nine milk and blood samples.

Herein, we found that better bacterial diagnostic system and choosing an appropriate technique for rapid detection, such as PCR and Real Time PCR, in addition to popular awareness and other functions of national veterinary medicine institute could control the diseases and decrease their incidence successfully.

Red blood cells play an essential role in the oxygen transport and the immune system. Moreover, hematologic parameters are an important clinical indicator of various diseases including anemia and metabolic syndrome.

The present study aimed to conduct genome-wide association studies (GWAS) based on gene-set enrichment analysis to identify the loci associated with hematological traits using 630K arrays.

For this purpose, the phenotype records included 498 genotyped Alpine Merino sheep were used for red blood cell count (RBC), hemoglobin (HGB), hematocrit (HCT), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and RBC volume distribution width coefficient of variation (RWD_CV). Genome-wide association study was performed with hematological traits using TASSEL software. Using biomaRt2 R package R, SNP was assigned to genes. GO, KEGG, DAVID, and PANTHER databases were used to assign the genes to functional categories.

11 SNP markers on chromosomes 1, 2, 3, 6, 8, 10, 11, 14, and 20 located in TRPC4, SPAT1, TMCC2 (RBC), KRT26, GPLD1, EPAS1 (HGB), RAC2, HSPD1, PDGFRA (HCT) and BBS1, HAG1, PIK3R3, STXBP5, FCER1G  (MCH, MHCH, RWD_CV) genes were identified. Based on the pathway analysis, 17 pathways from gene ontology and biological pathways were associated with hematological traits (P˂0.05). The pathways have important functions in the development and differential of red blood cells, hypoxia, adaptation process, environmental stress, and platelet activation.

In total, this study supported previous results from the GWAS of hematological traits, and also revealed additional regions in the sheep genome associated with important traits, using these findings could be potentially useful for genetic selection in the breeding programs.

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.

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.

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.

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.

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.