BMC Veterinary Research最新文献

Background: Salmonella is a leading cause of human acute bacterial gastroenteritis worldwide. Outbreaks of human salmonellosis have often been associated with consumption of contaminated poultry products. Various strategies have been explored to control this microorganism during poultry production and processing. Vaccination of broiler chickens is regarded as one of the effectives means to control this microorganism. The aim of the present study was to compare the epitope identification in the Salmonella enterica serotype Heidelberg FlgK protein by in silico prediction and in vivo experiment with mass spectrometry in association with immunoprecipitation proteomics.

Results: The Salmonella serotype Heidelberg FlgK protein contains 553 amino acids with a molecular mass of 61 kDa. This protein is conserved among Salmonella serotype Heidelberg isolates. The results show that both approaches identified three common shared consensus peptide epitope sequences at the positions of 77-95, 243-255 and 358-373 in the Salmonella serotype Heidelberg FlgK protein.

Conclusions: These findings provide a rational for further evaluation of these shared linear epitopes in vaccine development to cover the chicken population.

Background: This study aimed to evaluate the effects of selenium nanoparticles (SeNPs) and/or vitamin E (VE) on the growth, body composition, metabolic parameters, histopathology, and resistance of Nile tilapia to Aspergillus flavus.

Results: Monosex Nile tilapia fingerlings were sourced from the Bazina farm and hatchery in Ismailia Governorate, Egypt, where the experiment was also conducted. The fish were acclimatized for 15 days before the trial. A total of 240 fingerlings (average weight 46 ± 3.0 g/fish) were divided equally across 12 concrete tanks (1 × 1 × 1.2 m, 1 m³ capacity), with 20 fish per tank. The fish were fed a control diet (T0), which was a basal diet with no supplementation, or one of three experimental diets for 60 days: T1 (1 mg SeNPs/kg), T2 (100 mg VE/kg), and T3 (1 mg SeNPs + 100 mg VE/kg). The experiment followed a completely randomized design (CRD) with three replicates per treatment. The combination of SeNPs and VE (T3) resulted in the best feed conversion ratio. A slight but significant increase (P < 0.05) in whole-body composition was observed in all treatment groups compared to the control. Biochemical parameters, serum digestive enzyme activity, and antioxidant levels improved significantly with dietary supplementation. Histopathological analysis revealed somewhat lacerated gill arches in fish fed SeNPs, VE, or their combination, but the overall gill structure remained normal. The SeNPs + VE group exhibited improved villi length and normal morphology of portal veins and hepatic sinusoids, though some vacuolated hepatocytes were noted. Fish in the SeNPs + VE group had the lowest mortality rates and the highest resistance to A. flavus.

Conclusion: Supplementing diets with SeNPs and/or VE enhances growth, body composition, biochemical parameters, and histopathology in Nile tilapia. The combination of 1 mg SeNPs + 100 mg VE/kg improves immune response and growth, offering a promising strategy to enhance Tilapia health and productivity.

The potential use of feed supplements as immune-stimulant and growth-promoting agents in fish diets has drawn much attention. The current research investigated the effects of feeding Nile tilapia (Oreochromis niloticus) on white poplar (Populus alba L.) (WP) leaves powder as a dietary supplement on the growth, digestive functions, immune, and oxidant-antioxidant parameters. In addition, the fish resistance against the Aeromonas sobria (A. sobria) challenge was investigated. For 60 days, fish (n = 160; 34.61 ± 0.16 g) were divided equally into four groups, each had four replicates. Fish were fed on four isonitrogenous and isolipidic diets supplemented with varying levels of WP; 0 g/kg (WP0, crude protein (CP) = 37.18%; crude lipid (CL) = 9.98%), 2 g/kg (WP2, CP = 37.22%; CL = 9.56%), 4 g/kg (WP4, CP = 36.95%; CL = 9.47%), and 6 g/kg (WP6, CP = 36.88%; CL = 9.33%), where WP0 was the control diet. The results revealed that WP diets substantially boosted the growth (final body weight, weight gain, and specific growth rate) with an improvement of feed conversion ratio of Nile tilapia in a level-dependent manner with the WP6 group attaining the best outcomes. WP diets improved the amylase (4-6 g/kg level) and lipase (2-6 g/kg level) activity and the intestinal morphometric measures (2-6 g/kg level), where the WP6 group recorded the highest values. WP diets increased the growth hormone (2-6 g/kg level) and reduced leptin hormone and glucose levels (2-6 g/kg level). WP diets boosted the immune-antioxidant indices (total protein, albumin, globulin, complement 3, lysozyme, nitric oxide, total antioxidant capacity, glutathione peroxidase, and catalase) in a level-dependent manner and the WP6 group attained the highest values. All experimental groups exhibited 100% survival at the end of the feeding trial. During the A. sobria challenge, the survival of fish was improved in a level-dependent manner (2-6 g/kg) (80%, 85%, 95%, respectively) compared to the control (70%), where the WP6 group recorded the highest survival. Noteworthy, WP diets especially at a level of 6 g/kg can be used as a feed supplement for improving the health, growth, immune-antioxidant functions, and disease resistance of Nile tilapia.

This study aimed to reveal the effects of increasing levels of rubber seed cake (RSC) on growth performance, nutrient digestion metabolism, serum biochemical parameters, and rumen microbiota in Hu sheep. In this study, 48 Hu sheep, weighing 17.01 ± 0.57 kg at 3 months of age, were randomly divided into four treatments: 0% rubber seed cake (RSC0%), 6% rubber seed cake (RSC6%), 12% rubber seed cake (RSC12%) and 18% rubber seed cake (RSC18%), with 12 sheep per group. Compared to the RSC0%, the ADG and DMI of the RSC6% and RSC12% were increased (P > 0.05). The apparent digestibility of OM and EE quadratically (P < 0.05) changed with the increase of RSC supplementation, with the greatest apparent digestibility of OM and EE observed in the RSC6% diet. With increased RSC supplementation, the N intake and fecal N increased linearly (P < 0.05), and the apparent digestibility of N reduced linearly (P < 0.05). As the increase of RSC supplementation, the serum levels of IgA, IgM, IgG, IL-4, T-AOC, and GSH-Px increased linearly (P < 0.05), and the serum level of IL-6 reduced linearly (P < 0.05). The serum level of IL-1β reduced quadratically (P < 0.05) with the increased RSC dose, and the serum level of SOD increased quadratically (P < 0.05) with the increased RSC dose. The ruminal NH₃-N and the relative abundance of norank_Muribaculaceae quadratically (P < 0.05) changed with increased RSC supplementation, and the greatest relative abundance of norank_Muribaculaceae was observed in the RSC6% diet. In general, incorporating RSC into the diet of Hu sheep did not adversely affect growth performance and rumen fermentation characteristics. Supplementing with 6% RSC enhanced the relative abundance of norank_Muribaculacea in the rumen fluid and the immune and antioxidant capabilities. However, supplementing with 12 and 18% RSC might have negatively impacted nutrient digestion and metabolism. Therefore, this study recommended replacing corn and soybean meal with 6% RSC in the diet of Hu sheep.

Bullfrogs (Aquarana catesbeiana) are increasingly cultivated for their high nutritional value and adaptability to intensive aquaculture systems. However, ensuring optimal intestinal health and growth performance remains a challenge due to poor water quality and high stocking densities. This study evaluated the effects of varying dietary concentrations of citral, a natural compound from lemongrass essential oil, on the intestinal health, microbiota, antioxidant capacity, and growth performance of juvenile bullfrogs. A total of 200 juvenile bullfrogs (initial weight 6.85 ± 0.71 g) were randomly assigned into six groups, each receiving diets supplemented with citral at 0, 1, 2, 4, 8, and 16 mL/kg feed for 8 weeks. Citral supplementation significantly improved intestinal morphology, with goblet cell numbers, mucosal thickness, and villus-to-crypt ratios peaking at 2-4 mL/kg (P < 0.05). Optimal doses of 2-4 mL/kg also enhanced digestive enzyme activities, with α-amylase, lipase, and pepsin activities showing significant increases compared to the control group (P < 0.05). Antioxidant markers, including total antioxidant capacity (T-AOC) and glutathione (GSH), were highest at 2 mL/kg, while higher citral concentrations reduced superoxide dismutase (SOD) and catalase (CAT) activities, indicating potential oxidative stress at 8-16 mL/kg (P < 0.05). Citral also modulated the intestinal microbiota, increasing the relative abundance of beneficial bacteria such as Cetobacterium at 1-2 mL/kg (P < 0.05). However, microbial diversity decreased significantly at concentrations above 4 mL/kg. Growth performance analysis revealed that 4 mL/kg citral supplementation significantly improved weight gain rate (WGR), specific growth rate (SGR), carcass weight (CW), and feed efficiency (FE), while survival rates declined at 16 mL/kg (P < 0.05). A linear regression model determined the optimal dietary citral concentration to be 3.216-3.942 mL/kg. This study concludes that dietary citral at 2-4 mL/kg optimally enhances growth performance, intestinal health, and antioxidant capacity in juvenile bullfrogs, while higher concentrations may disrupt gut health and oxidative balance. These findings provide valuable insights into the use of natural compounds like citral for sustainable aquaculture practices.

Background: Bovine mastitis is a major challenge in dairy farms. Since the agents commonly used for pre- and post-dipping can affect the udder health by modifying milk microbiota, alternative products are needed. This study aimed to evaluate the effect of the use of pre- and post-dipping formulations containing the fermented broth of Nisin A-producing Lactococcus cremoris FT27 strain (treated group, TR) on the abundance and biodiversity of milk microbiota as compared to iodine-based commercial disinfectants (control group, CTR) during a three-month trial. The experiment was conducted on 20 dairy cows, divided into two groups (CTR and TR) of 10 lactating cows each. Milk samples were collected from two selected healthy quarters of each cow at 3 time-points. Microbial communities were investigated by cultural and sequence-based methods, and analyzed through bioinformatic and statistical approaches.

Results: Clear differences in bacterial community composition were observed among groups, with higher species richness in TR, especially of Staphylococcus, Enterococcus, Lactococcus, and Streptococcus genera. The microbiota was dominated by Firmicutes, followed by Actinobacteriota, Proteobacteria, and Bacteroidota. Staphylococcaceae family was significantly higher in TR (p < 0.009), whereas Carnobacteriaceae, Mycobacteriaceae, and Pseudomonadaceae were significantly lower (p = 0.005, p = 0.001, and p = 0.040, respectively). CTR had considerably higher abundances of the genera Alkalibacterium (p = 0.011), Pseudomonas_E (p = 0.045), Corynebacterium (p = 0.004), and Alloiococcus (p = 0.004), and lower abundances of Staphylococcus (p < 0.009). Milk microbiota changed noticeably during the experimental period, regardless of treatment. A significant decrease was observed in both groups for Firmicutes_A phylum, with an increment in Actinobacteriota phylum, Propionibacteriaceae family, and Cutibacterium genus. Streptococcaceae significantly decreased in CTR (p = 0.013) and rose in TR (p = 0.001). Several differences were observed between the two groups during the experimental period. Streptococcus genus almost disappeared in CTR (p = 0.013), whereas it significantly increased in TR (p = 0.001). Three and twelve enriched groups were significantly identified respectively in CTR and TR using LEfSe.

Conclusions: The use of Nisin A-based teat dip formulations could be linked to greater microbial diversity compared to commercial products. Despite the influence of seasonality, the experimental formulations maintained higher milk biodiversity, suggesting that lactic acid bacteria metabolites prevent alterations in the milk microbiota.

This research investigates the effects of dietary supplementation with Ecobiol plus^® (Bacillus amyloliquefaciens CECT5940) on the growth performance, physiological responses, oxidative stress, and immune status of Nile tilapia (Oreochromis niloticus) fingerlings revealed to Aeromonas hydrophila. A total of 525 Nile tilapia fingerlings, averaging 30.00 ± 5.00 g in initial weight, were randomly divided into four groups (control and three experimental groups), each with three replicates of 25 fish. Ecobiol plus^® was integrated in the diet at concentrations of 0.0 (control), 0.1, 0.2, and 0.4 g/kg feed. Fish were fed at 3% of their biomass daily, with biweekly adjustments based on growth. The feeding trial lasted 8 weeks, followed by a 15-day challenge with Aeromonas hydrophila to evaluate immune responses and survival outcomes. The group receiving 0.4 g/kg of Ecobiol plus^® exhibited the most significant improvements in growth performance, including higher weight gain, specific growth rate, and feed conversion efficiency (p < 0.05). Blood and biochemical assessments indicated increased hemoglobin, total protein, and globulin levels, reflecting improved physiological and immunological conditions. Additionally, lysozyme activity and phagocytic response were markedly enhanced, demonstrating the probiotic's immune-boosting potential. Histopathological evaluations revealed reduced gut, gills, and hepatopancreas lesions, especially in groups with higher supplementation levels. Fish in Group T4, fed with 0.4 g/kg Ecobiol plus^®, achieved the best growth performance, with a final weight of 77.96 ± 5.53 g, a weight gain of 42.46 ± 3.18 g, and a specific growth rate (SGR) of 1.51%/day, compared to the control group (T1) with a final weight of 75.26 ± 3.87 g, weight gain of 35.76 ± 2.08 g, and SGR of 1.24%/day. Survival rates considerably increased in the treated groups, with T4 exhibiting the highest rate of 96.00%, followed by T2 (94.68%), T3 (92.00%), and T1 (81.32%). Additionally, the LD50 of A. hydrophila was determined to be 3 × 10⁷ CFU/mL, underscoring the protective effect of Ecobiol plus^® in enhancing fish immunity and resilience against bacterial challenges. These results suggest that Ecobiol plus^® can be a natural, antibiotic-free additive to strengthen growth and disease resistance in Nile tilapia. The optimal inclusion level of Ecobiol plus^® is 0.4 g/kg for maximum benefit.

Background: Parvoviridae is a family of single-stranded linear DNA viruses whose members infect both vertebrate and invertebrate species of animals, causing diseases of various systems and often associated with pathology of the gastrointestinal tract. Additionally, parvoviruses are known to induce illnesses causing diarrhea in various avian species as well; however, data on their occurrence and pathology in pigeons is scarce.

Results: In this study, we developed molecular biology methods to detect and quantify parvovirus genetic material in samples acquired from racing pigeons of different health status. Our intention was to determine a connection between the presence of the virus and the occurrence of clinical signs in sampled birds. The results of quantitative analysis indicate no direct association of parvoviruses with the manifestation of enteric disease in pigeons. High-throughput sequencing was performed on samples testing positive in quantitative PCR with TaqMan probe and in digital droplet PCR. It allowed us to assemble two coding-complete pigeon parvovirus genomes, one belonging to new species and referred to as pigeon parvovirus 2, and the second which is a member of species Aveparvovirus columbid1. Additionally, we analyze two coding-complete genomic sequences acquired from pigeon feces in USA, one representing species Aveparvovirus columbid1 and one being a member of Chaphamaparvovirus genus in Hamaparvovirinae subfamily.

Conclusions: This is the first report of parvovirus in pigeons outside Asia. The findings of our research emphasize the need to further explore the poorly understood biology and pathology of pigeon parvoviruses.

Background: Bovine viral diarrhoea virus genotype 1 (BVDV-1) and bluetongue virus (BTV) are potent viral pathogens that may be transmitted through semen, resulting in the spread of diseases via artificial insemination. Thus, establishing an early detection method for BVDV-1 and BTV infection is important for the trading of semen. In this study, we developed two RT‒ddPCR methods to detect BVDV-1 and BTV, and each method was evaluated for repeatability, limit of detection and specificity. The sensitivity of these methods was compared with that of RT‒qPCR (WOAH) by analysing clinical samples.

Results: The RT‒ddPCR results revealed that both methods exhibited good repeatability at low concentrations, with detection limits of 1.05 copies/µL and 0.662 copies/µL per reaction for BVDV-1 and BTV, respectively; additionally, both methods exhibited high specificity and did not exhibit cross-reaction with other important semen-transmitted pathogens. Eighty bovine semen samples and twenty mixed semen samples were tested. The results revealed that the positivity rates of BVDV-1 and BTV RT‒ddPCR (25% and 23%, respectively) were greater than those of RT‒qPCR (19% and 18%, respectively).

Conclusions: RT‒ddPCR was highly sensitive for detecting low concentrations of BVDV-1 and BTV in clinical samples and could be a good supplement for qPCR testing.

Background: Coccidia are among the primary pathogens causing diarrhea and even fatalities in lambs. With the increasing use of chemical drugs to treat coccidiosis, the problem of drug resistance is becoming more and more threatening. Therefore, there is an urgent need to identify novel alternative drugs for the treatment of the lamb coccidia. In this study, the effect of different doses and extraction methods of Artemisia annua (A. annua) on anticoccidial activity and growth performance was assessed by oocysts output (OPG), fecal index, average daily gain (ADG) and the new production value of experimental lambs. High-throughput sequencing technology was employed to investigate the effect of A. annua on the intestinal microbiota and metabolites of lambs afflicted with coccidiosis.

Results: The results revealed that all A. annua treatment groups exhibited good anticoccidial effects. According to the soft stool index and ADG analysis, the Low-dose A. annua (AL) and A. annua alcohol extract (AA) groups demonstrated a better overall effect. The microbiota and metabolites of lambs changed after A. annua was administered. Unclassified_Muribaculaceae exhibited a significant positive correlation with ADG (P < 0.05) and a negative correlation with OPG, although the latter was not statistically significant (P > 0.05). Alistipes displayed a significant negative correlation with ADG (P < 0.05), and a positive correlation with OPG (P > 0.05). Additionally, UCG 005 exhibited a highly significant negative correlation with OPG (P < 0.01).

Conclusion: The above results demonstrated that AL and AA groups had more effective anticoccidial action. Unclassified_Muribaculaceae could be employed as a suitable probiotic to enhance weight gain in lambs, while UCG-005 could inhibit intestinal Eimeria colonization in lambs. Alistipes may serve as a biomarker for predicting the risk of intestinal coccidia outbreaks in lambs. A. annua induced significant changes in gut microbiota, accompanied by corresponding changes in metabolites. These differences in gut microbiota and metabolites provide valuable insights for subsequent research on the mechanisms underlying anticoccidial action.