مجله تحقیقات دامپزشکی
سال هفتاد و نهم شماره 4 (زمستان 1403)

Blood filaria is an important arthropod-borne parasite concerning public health and causing disease in the host. Until now, no study has been conducted on the infection of dogs with blood filariasis in Ilam Province, Iran. This province has three different climates and is home to Culex species, which are the most prevalent vectors of the parasites reported in this province.

The present study investigated the infection of dogs with Dirofilaria immitis and Acanthocheilonema reconditum (Dipetalonema reconditum) in Ilam Province, Iran.

In this study, blood samples were collected from 139 dogs from Ilam Province. Blood samples were examined using the modified Knott method, and the polymerase chain reaction (PCR) was performed using two pairs of specific primers of the internal transcribed spacer 1 (ITS1) gene.

In a blood specimen from Sirvan City, microfilaria of Dirofilaria immitis (34 microfilariae in 1 mL of blood) was observed by the modified Knott test. The mean length and width of the microfilaria were 240 ± 8.72 and 5.4 ± 0.33 µ, with the straight end of the tail. A blood sample from Dehloran City and two samples of Sirvan were positive, and PCR results revealed a specific band at 155 bp in length. Two samples of Ilam City and one sample of Sarablah City were positive for Acanthocheilonema reconditum, and an amplicon with a length of 155 bp was observed.

The frequencies of infection with Dirofilaria immitis and Acanthocheilonema reconditum in Ilam Province were 2.6% and 3%, respectively. In the present study, infected dogs were reported from the cities of Sirvan, Sarablah, and Ilam, whose regions experience moderate winters without serious cold temperatures.

Aflatoxins are among the most important contaminating mycotoxins in poultry feeds. To reduce their adverse effects, toxin binders are applied.

This study was conducted to evaluate the adverse effects of moderate levels of aflatoxins in broilers' diets and the ability of two commercial toxin binders to reduce these effects.

In the first experiment, 480 male day-old chicks were randomly allocated to six treatments and reared for 42 days. The treatments included A: basal diet, B: basal diet+100 μg/kg aflatoxin, C and D: basal diet+3 kg of each commercial toxin binder, respectively, E and F: basal diet+3 kg of each commercial toxin binders, respectively, +100 μg/kg aflatoxin. In the second experiment, 360 male day-old chicks were randomly divided into six treatments. The treatments included A: basic diet, B: basic diet+200 μgkg-1 aflatoxin, C and D: basic diet + 2.5 and 5 kg of first toxin binder+200 μg/kg aflatoxin, D and E: The basic diet+2.5 and 5 kg of the second toxin binder+200 μg/kg aflatoxin. Production performance, relative weights of internal organs, serum biochemical parameters, histopathologic findings, and antibody levels against Newcastle disease virus (NDV) were evaluated.

Feeding the broiler chickens with a diet containing 100 μg/kg of aflatoxin only reduced weight gain in the first 14 days but did not affect other parameters. In the second experiment, 200 μg/kg of aflatoxin significantly increased feed consumption, feed conversion ratio, and gamma-glutamyl transferase (GGT) enzyme in the first 10 days. Adding toxin binders to the feed could not improve performance indicators, and only in the second experiment they could alleviate the increase in GGT enzyme. There are no significant differences between groups in the two experiments regarding the hepatic histopathology and NDV antibody levels.

The broiler feed contamination with moderate levels of aflatoxins up to 200 μg/kg did not significantly affect the economic performance, serum biochemical parameters, and histopathologic lesions. Regarding the health and performance of the broilers, the positive effects of toxin binders in chickens confronting moderate levels of aflatoxins could not be observed.

Foot-and-mouth disease is one of the most important viral diseases affecting livestock. Types O, A, and Asia 1 of the foot-and-mouth virus have been endemic in Iran for a long time.

The current research investigated the molecular epidemiology, affinity, and changes in antigenicity of the foot-and-mouth virus in relation to vaccine viruses in Razavi Khorasan province from 2021 to 2022.

In this study, 51 samples taken from suspected animals exhibiting clinical symptoms between 2021 and 2022in the province were analyzed by ELISA, real-time RT-PCR and RT-PCR tests, and cell culture. The affinity of antigenicity of five circulating viruses with the vaccine virus (R-value) produced by the Razi Vaccine Research and Serum Institute was calculated.

The results showed that 34.52% of suspected samples were positive, with 33.33% belonging to sheep and 35.72% belonging to cattle; all samples were type O. By cell culture in 2021, seven samples from cows and two samples from sheep were isolated, while in 2022, five samples from cows and two samples from sheep were isolated. Determining the nucleotide sequence of five samples of the viruses showed that the virus O/IRN/KHO/1/2022 has the most similarity (98.5%) with the virus O/IRN/KHO/3/2022, whereas the virus O/IRN/KHO/7/2022 had the least similarity (90.7%) with the virus O/IRN/KHO/4/2022. Also, the similarity of the nucleic acids of all the isolated viruses with the virus used in the vaccine MN539142.1/O/IRN/93/2016 was more than 87.5% in all five cases, and the antigenic similarity coefficient of the circulating virus with the virus vaccine was greater than 0.3.

The vaccine from the Razi Vaccine Research and Serum Institute demonstrated the ability to produce protective antibodies and establish the necessary immunity against foot-and-mouth disease viruses circulating in Razavi Khorasan Province between 2021 and 2022.

Salmonella Enteritidis (SE) in chickens is associated with growth depression and mortality of young chicks. Moreover, poultry products are identified as a prominent source of SE, which can cause food-borne diseases in humans. Therefore, considering the economic and public health significance of SE, control of this bacterial infection is important.

This study aims to assess colonization and invasion of SE after exposure to the thyme essential oils in experimentally infected broiler chickens.

Minimum inhibitory concentration (MIC) of thyme essential oils was measured by broth microdilution method. A total of 75 one-day-old Ross 308 chicks were randomized to three experimental groups of 25 (A, B and C). At 9 days old, groups A and B were challenged with 108 colony-forming unit (CFU) of SE with and without previous exposure to thyme essential oils at 50% MIC. Group C (control) received a bacteria-free buffer. On days 9, 16 and 24 after the challenge, cloacal swabs and samples from visceral organs were collected from slaughtered birds and evaluated for the presence of Salmonella.

The MIC of thyme essential oil for SE was obtained 1.25 mg/mL. Results of experimental infection showed a significant reduction of SE in the cloaca, ceca, liver, and spleen of group A compared to group B throughout the sampling times. On day 16 after infection, Salmonella was isolated at 1 and 7.4 log CFU/g of cloacal swabs and at 3.2 and 9.2 log CFU/g of ceca in groups A and group B, respectively.

According to the results, previous exposure of SE to the thyme essential oil at a sub-inhibitory concentration can reduce the colonization and invasion of this pathogen in broiler chickens.

Probiotics are of interest to researchers due to their beneficial effects in controlling the negative impacts of heat stress in broiler chickens.

The present study was performed to investigate the effects of three different probiotics administered via drinking water on the growth performance and sensory and qualitative indices of breast meat in broilers under heat stress.

A total of 150 one-day-old Cobb 500 broilers were divided into five groups (four replicates with 10 birds in each) in a completely randomized design. The treatment groups included: negative control (normal temperature), positive control (heat stress), HSBacil (heat stress and Bacillus probiotic), HSLAB (heat stress and Lactobacillus probiotic), and HSMix (heat stress and a mixture of Bacillus and Lactobacillus probiotics). Chronic heat stress induction and probiotic administration were performed from 21 to 42 days of age.

After the challenge, the broilers in the positive control group had lower feed intake and weight gain, as well as a greater feed conversion ratio compared to those in the negative control group. Broilers in the HSLAB and HSMix groups exhibited greater weight gain and a more favorable feed conversion ratio compared to those in the positive control group (P<0.05). There was no difference in weight gain between the broilers in the HSLAB and HSMix treatments compared to the negative control treatment. The sensory scores of the breast meat in the positive control group were lower than the negative control group (P<0.05). The use of probiotics improved the sensory indices of breast meat (P<0.05). The HSMix treatment showed no significant difference from the negative control treatment in most of the meat sensory indices. Peroxide value in fat tissue in positive control birds was greater than negative control birds (P<0.05). The peroxide value in the HSMix treatment was lower than the positive control treatment (P<0.05).

The results showed that Bacillus and Lactobacillus probiotics, individually or in combination, are effective in improving the growth performance and meat sensory indices, as well as reducing the peroxide value in broilers under heat stress. These probiotics can be a useful strategy to mitigate the negative effects of heat stress.

Salmonella typhimurium is one of the most important causative agents of gastrointestinal diseases in humans and animals. Probiotics can inhibit pathogens by producing antimicrobial compounds.

The aim of this study was to investigate the effect of a probiotic mixture (Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus brevis) on the gut-brain axis of male Sprague-Dawley rats infected with S. typhimurium.

In this study, 21 adult male Wistar rats with an average weight of 220-250 g were randomly divided into three groups: the control group receiving daily water and food, the second group (infected) receiving S. typhimurium (109 CFU/ml), and the third group (treatment) receiving the probiotic mixture along with S. typhimurium infection.

The findings showed a significant increase in cortisol levels and some inflammatory factors in the infected group, while a significant decrease in these factors was observed in the treatment group. Additionally, serotonin levels increased in the treatment group. The results indicated that serotonin and dopamine levels increased, while cortisol concentration decreased in the treatment group compared to the infected group (P<0.05). Moreover, significant changes were observed in the levels of malondialdehyde, total antioxidant capacity, and the expression of IL6, TNFα, NLRP genes, and inducible damages in brain and gut tissues in the treatment group compared to the infected group (P<0.05).

These findings suggest that probiotics can have significant positive effects on reducing inflammation and improving immune response against S. typhimurium infection. Finally, this study demonstrates that the probiotic mixture could be an effective complementary treatment for reducing bacterial infection-related complications.