Veterinary Research Forum

Abstract Among global concerns about antibiotic resistance, it is necessary to identify food-safe alternatives to enhance production. This study aimed to evaluate the impact of mannan oligosaccharides (MOS) inclusion to replace antibiotic growth promoters (AGP) in the diets of ISA Brown laying hens aged between 23 and 31 weeks. Two hundred forty hens were grouped into five treatments: Control, AGP (130 ppm of enramycin 8.00%), and 100, 200, and 400 ppm of MOS. Each treatment had 16 experimental units (each unit with n = 3) in a randomized block experimental design. Productive data (egg production %, feed intake, egg weight), egg quality variables (albumin height, yolk weight, albumin, yolk %, weight eggshell, eggshell %, equator thickness, width-pole thickness, and Haugh units), organ weights (ovary, liver, and cecum) and jejunal histomorphometry were analyzed. The egg production was not affected by the substitution of AGP by MOS. Furthermore, MOS supplementation resulted in significantly increased feed intake, larger egg weight, higher yolk weight and higher body and ovarium weight compared to the AGP group. Besides, MOS supplementation at 400 ppm demonstrated significant improvements in jejunal villus morphology indicating enhanced intestinal health. These findings highlighted the potential of MOS as an alternative to AGP, offering benefits such as improved feed intake, egg quality and intestinal health in laying hens at 400 ppm.

Abstract Fungal contamination in drinking water has garnered considerable attention over the past few decades, especially considering the detrimental consequences of pathogenic fungal species on both human and animal health. The formation of biofilms by certain species is a considerable factor contributing to the emergence of severe fungal infections. This research was designed to isolate and identify fungi, particularly those capable of forming biofilms from 150 samples of drinking water sourced from various locations. The isolated fungal species were tested for them in vitro biofilm formation using a microtitration plate method and the crystal violet assay was applied to quantify the established biofilms. The effectiveness of three disinfectants, namely ozone, chlorine, and hydrogen peroxide, in preventing the formation of biofilms by the most isolated fungal species was monitored. The findings indicated that Aspergillus species were the most prevalent in drinking water, comprising 63.33% (95/150) of the total number of fungal species identified. Aspergillus fumigatus and Aspergillus flavus were identified as the primary contributors to biofilm formation in drinking water distribution systems with prevalence rates of 41.00 and 34.00%, respectively, among all Aspergillus species. The outcomes of the in vitro studies demonstrated that the ozone disinfectant exhibited promising results in inhibiting fungal biofilms compared to chlorine and hydrogen peroxide. In conclusion, these findings provided valuable insights for water distribution authorities to develop effective regimens for controlling biofilm-forming fungal species using suitable antifungal biofilm disinfectants.

Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the COVID-19 pandemic. The receptor binding domain (RBD), located at the spike protein of SARS-CoV-2, contains most of the neutralizing epitopes during viral infection and is an ideal antigen for vaccine development. In this study, bioinformatic analysis of the amino acid sequence data of SARS-CoV-2 RBD protein for the better understanding of molecular characteristics was performed. The SARS-CoV-2 RBD gene was inserted into pET-28a vector, and efficiently expressed in E. coli system. Then, the recombinant proteins (RBD monomer and RBD dimer protein) were purified as antigen for animal immunization. Furthermore, the results showed that the recombinant proteins (RBD monomer and RBD dimer protein) had adequate immunogenicity to stimulate specific antibodies against the corresponding protein in immunized mice. Taken together, the results of this study revealed that RBD protein had a high immunogenicity. This study might have implications for future development of SARS-CoV-2 detection.

Abstract Testicular ischemia-reperfusion (I/R) injury during testicular torsion is strongly influenced by oxidative stress caused by excessive accumulation of unscavenged reactive oxygen species. This study aimed to investigate the effects of intra-peritoneal administration of Mito-TEMPO (MT) on I/R injury in testicular torsion/detorsion (T/D) in mice. Forty-two male mice were divided into seven groups including 1 control and 6 treatment groups (360° T/D, 720° T/D, 360° T/D + 0.70 mg kg^-1 MT, 360° T/D + 1.00 mg kg^-1 MT, 720° T/D + 0.70 mg kg^-1 MT, and 720° T/D + 1.00 mg kg^-1 MT). After inducing 360° and 720° clockwise testicular torsions for 2 hr, sperm parameters, apoptosis-related genes expression, and in vivo fertility index were evaluated. The results showed that 720° T/D can lead to increased abnormal sperm morphology, sperm DNA damage, and Bax expression, while the Bcl-2 expression was reduced compared to the other groups. In addition, it also had negative effects on sperm total and progressive motilities as well as viability and plasma membrane functionality (PMF). The results also showed that administration of MT to T/D mice can result in a reduction in abnormal sperm morphology, DNA damage, and Bax expression. It could also increase sperm total and progressive motilities, viability and PMF, Bcl-2 expression, and in vivo fertility index. Based on our results, it is concluded that MT, when administered after spermatic cord torsion in mice, provides significant protection against acute testicular T/D injury.

Abstract Leydig cells play a crucial role in male reproductive physiology, and their dysfunction is often associated with male infertility. Hypoxia negatively affects the structure and function of Leydig cells. This study aimed to investigate the impact of melatonin on the c-Jun N-terminal kinase (Jnk), P38, and extra-cellular signal-regulated kinases 1 and 2 (Erk1/2) mitogen-activated protein kinase (MAPK) signaling pathways in TM3 mouse Leydig cells under hypoxia induced by cobalt (II) chloride (CoCl₂). The TM3 cell line was utilized as a subject of research, and 100 μM CoCl₂ was employed to induce hypoxia. Following the addition of 10.00 ng mL^-1 melatonin, quantitative reverse transcription-polymerase chain reaction and western blot analyses were conducted to assess the gene expression and protein level of Jnk, p38, and Erk1/2, while enzyme-linked immunosorbent assay was used to measure testosterone secretion. The results showed that melatonin significantly increased testosterone production in the CoCl₂ + melatonin group compared to the CoCl₂-treated group. Furthermore, melatonin elevated both the protein level and mRNA expression of Erk1/2, Jnk, and p38 genes in the CoCl₂ + melatonin group compared to the CoCl₂ group. In conclusion, melatonin activated the Jnk, p38, and Erk1/2 MAPK signaling pathways and enhanced testosterone production in the presence of CoCl₂ in TM3 cells.

Abstract The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus is the causative agent of the emerging zoonotic respiratory disease. One of the most important prerequisites for combating emerging diseases is the development of vaccines within a short period of time. In this study, antigen-irradiated, inactivated SARS-CoV-2 viruses and the disaccharide trehalose were used to enhance immune responses in the Syrian hamster. The SARS-CoV-2 virus was isolated from tracheal swabs, confirmed by Real-Time Polymerase Chain Reaction (RT-PCR), and propagated on Vero cells. For inactivation, it was irradiated with 14.00 kGy gamma radiation. Evaluation of the antigenic properties of the spike protein subunit S1 showed that the antigens were intact after gamma irradiation. The gamma-irradiated and formalin-treated viruses were used to immunize hamsters in four vaccine formulations. Neutralizing antibodies increased significantly in all vaccinated groups three weeks after the second and third vaccinations. The concentration of secretory immunoglobulin A in the irradiated vaccine plus trehalose increased significantly in nasal lavage and nasopharyngeal-associated lymphoid tissue fluids three weeks after the second and third vaccinations. The lymphocyte proliferation test in the spleen showed a significant increase in all vaccinated hamsters, but the increase was greater in irradiated vaccine plus trehalose and irradiated vaccine plus alum. We can recommend the irradiated inactivated vaccine SARS-CoV-2 plus trehalose (intra-nasal) and another irradiated inactivated vaccine SARS-CoV-2 plus alum (subcutaneous) as safe vaccines against coronavirus disease of 2019 (COVID-19), which can stimulate mucosal, humeral, and cellular immunities. However, the protectivity of the vaccine against COVID-19 in vaccinated hamsters must be investigated in a challenge test to assess the potency and efficiency of vaccine.

Abstract The cooling procedure markedly diminishes the quality of guinea pig (Cavia porcellus) sperms, primarily because their membranes are highly susceptible to this process. This susceptibility triggers the generation of reactive oxygen species and free radicals, ultimately leading to lipid peroxidation in the sperm membrane. Surprisingly, there has been a lack of research on the use of Tris-based extenders to safeguard guinea pig sperm under refrigeration conditions. This study aimed to assess the viability of guinea pig spermatozoa diluted in Tris buffer-based extenders during storage at 5.00 ˚C. Sperm collection was carried out through castration of the animals. For this study, 10 adult male guinea pigs were utilized, being divided into four groups including phosphate-buffered saline (PBS), human tubal fluid (HTF), Tris-citric-glucose (TCG), and Tris-fructose-yolk (TFY) cultures. Evaluations including sperm motility, morphology, plasma membrane integrity, viability, and total count were conducted at 0, 24, and 48 hr after sampling. The results obtained indicated that at the 24-hr and 48-hr marks of the experiment, both overall and progressive motility percentages, viability, plasma membrane integrity, and morphology of sperms in the PBS and HTF cultures exhibited a significant increase in comparison with the TCG and TFY cultures. Consequently, it can be inferred that PBS and HTF cultures are highly effective in preserving the quality of guinea pig spermatozoa.

Abstract Infectious canine cyclic thrombocytopenia or canine anaplasmosis is an infectious disease caused by Anaplasma platys. In Mexico, cases of human infection have been reported. The present cross-sectional study aimed to determine the frequency of A. platys infection in the municipality of Veracruz, Mexico, by nested polymerase chain reaction method. A total of 100 blood samples from dogs living in the municipality were collected and analyzed between March and June 2022. A descriptive analysis of blood samples for hemoparasites frequencies was performed with the free online software VassarStats. The evaluated variables were sex, street access, usage of ticks control methods, and living environment. The free online software WinEpi software was used to calculate odds ratio (OR) and confidence interval (CI: 95.00%). Out of 100 analyzed blood samples, 27 were confirmed positive for A. platys. The only risk factor found was the absence of tick prevention methods (OR = 9.81; 95.00% CI: 23.00 - 44.50). In conclusion, the frequency of A. platys was 27.00% and no risk factors were identified.