Though recently considered a therapeutic treatment for commercial broilers, little is known about the effects of bacteriophages on native, slow-growing birds. This study evaluated their efficacy against Salmonella enterica subsp. enterica serovar Typhimurium infected Noi chicken, a native Vietnamese broiler breed. In total, 420 birds were used in a completely randomized design consisting of seven treatments and four replicates of 15 birds. The treatments were NC (negative control), PC (positive control, S. Typhimurium challenged); NC+B1 and NC+B2 (negative control plus B1 or B2 bacteriophage, respectively); PC+B1, PC+B2 (positive control plus B1 or B2 bacteriophage, respectively) and PC+B1B2 (positive control plus both B1 and B2 bacteriophages). After four weeks of infection, the mortality rate in the PC group was 51.1% compared with 11.1% in the PC+B1B2 treatment. Bacteriophage administration had resulted in increased weight gain and decreased feed conversion ratio, particularly when both phages were included in the treatment (p<0.001). Moreover, the relative percentage of carcass weight was lowest in the PC treatment (66.9%) (p<0.001), whereas the other treatments registered similar carcass weight values. Regarding the internal organs, liver weight percentage was higher in the non-treated Salmonella group, and enlarged spleens were also noted in infected chickens even when treated with bacteriophages. The correlation between phage administration and blood parameters was unclear. Although the use of two bacteriophages for therapy was determined to be preferable for the majority of the criteria examined, further genetic characterization of the phages will be required before they can be widely used in chicken farms.

Background and Aim: Probiotic species have been proven to be beneficial on broiler performance; however, most studies have focused on industrial chickens with fast growth, whereas little information concerning the use of these species on native chickens is available. This study aimed to investigate the effects of probiotics Lactobacillus plantarum (LP) and Bacillus subtilis (BS) on the mortality, growth rate, and carcass characteristics in native Noi chickens challenged with Salmonella Typhimurium. Materials and Methods: We divided 420 1-day-old Noi chicks into seven different treatment groups (n = 60): negative control (no S. Typhimurium, no probiotics or antibiotics); positive control (PC, S. Typhimurium infection, no probiotics or antibiotics); and S. Typhimurium infection and supplementation with LP, BS, LP + BS, enrofloxacin, and commercial probiotics, respectively. Treatment was for 96 days, and the chicks were orally challenged with S. Typhimurium at 22 days old. Results: No deaths occurred during the 4 weeks post-infection in the negative control, LP, or LP+BS groups. The PC group had the highest mortality rate (20%). Re-isolation of S. Typhimurium from the liver, spleen, and heart showed reduced bacterial counts at 1 week post-infection in the LP, BS, and LP + BS groups. The lowest body weight gain was observed in the PC group (949 g/bird), and chicks in the LP group gained 1148 g/bird. An improved feed conversion ratio was noted in the groups receiving probiotic supplementation (3.42–3.50 kg feed/kg gain). There was little evidence that probiotics affected carcass percentage and related parameters, such as breast, thigh and drumstick, and wings. Conclusion: Lactobacillus plantarum or BS dietary supplementation to native Noi broilers resulted in a lower mortality rate and improved body weight gain but did not affect carcass characteristics.

The present study was conducted aiming to isolate and characterize bacteriophages with lytic activity against Escherichia coli infected poultry. A total of 72 samples of soil from 18 chicken farms were collected in six provinces in the Mekong Delta, Vietnam. Samples were primarily subjected to rapid detection methods, and then isolation of phage was done by a double agar layer method using E. coli as the host system. Phages were characterized on the basis of plaque morphology, pH susceptibility and host range. Results showed that the recovery of phages in soil was at a high proportion (73.6%), in which the percentage of phage isolates was higher from Noi chicken farms (66.6%) as compared to broiler chicken farms (58.3%). Four different phage morphotypes were observed against E. coli. There was a high rate of phages which existed at pH 2.0 at 26.4%. The percentage of phages that could survive from pH 5.0 to pH 3.0 significantly decreased from 84.9% to 39.6%. TEM analysis performed for MHH6 and PR2 which had widest host range, revealed that both phages belong to the Myoviridae family. It could be concluded that the MHH6 and PR2 phages have a wide host range and thus exhibit the potential to be used as a drug substitute tool against E. coli infection in chickens.

Context Source and composition of feed influence rumen microbial community, which determines efficiency of feed digestion and thus productivity in ruminants. Therefore, changes in the structure, function and diversity of the rumen microbial populations in response to changes in diet provide an understanding in the rumen fermentation process. Aims The present study, consisting of two experiments, was conducted to determine the effects of supplementing different protein and energy sources on the rumen bacterial community in cattle. Methods The dietary treatments of the first experiment, which evaluated the effect of protein sources, were as follows: (i) Hymenachne acutigluma grass, rice straw and rice bran (1.5 kg/head.day; C1), (ii) C1 plus 120 g urea/head.day (C1 + U), (iii) C1 plus 720 g soybean/head.day (C1 + SM), and (iv) C1 plus 720 g of blood and feather meal (in 1:1 ratio)/head.day (C1 + BFM). The treatments in the second experiment were (i) Hymenachne acutigluma grass, rice straw and concentrate (1.5 kg/head.day; C2), (ii) C2 plus 250 g fish oil/head.day (C2 + FO) and (iii) C2 + 250 g soybean oil/head.day (C2 + SO). At the end of the 90-day feeding trial, rumen fluids were extracted for microbial DNA isolation to identify the microbe species by the polymerase chain reaction–denaturing gradient gel electrophoresis method and sequencing of the 16S rRNA region. Key results The sequences of some DNA bands were closely related to the bacteria strains of the Prevotella, Cytophaga, Capnocytophaga, Cyanobacterium, Catonella, Faecalibacterium, Lachnospiraceae, Ruminococcaceae, Propionivibrio, Galbibacter, Moorellaglycerin, Escherichia coli and Klebsiella alba groups, with similarity levels ranging from 73% to 96%. In addition, the Prevotella species was found in both the protein and the energy supplement trials, and irrespective of diet supplements, the Firmicutes and Bacteroidetes were the prominent groups in the rumen. Conclusions Firmicutes and Bacteroidetes are the two dominant groups of rumen microflora, and Bacteroidia and Clostridia classes together with the Prevotella genus are predominant in the rumen irrespective of protein and energy sources. Implications Our findings provided evidence on the effect of diet on the interaction of rumen microbial community and have important implications in establishing optimal diets for cattle.

This study was conducted to isolate and characterize the bacteriophages capable of lysing Aeromonas hydrophila causing hemorrhagic septicemia in striped catfish (Pangasianodon hypophthalmus). The isolation and characterization were conducted in various samples of water, sludge, intestines and kidneys of animal. It was shown that, a total of 64 bacteriophages (58.2%) were isolated from 110 samples, with the highest value being from sludge samples (100%). When phages were tested in different pH levels (2-10), the above 64 phages were well adjusted to the pH 5-8 after 24 hours at 28 o C, representing a rate of more than 60%. In addition, in one hour, 50% of the phages could survive at different temperatures (4 o C, 20 o C, 60 o C, 80 o C, 100 o C, and 120 o C) with no effects on phages observed at 4 o C and 20 o C. From the pH and temperature tests, six phages (B.N26, B.N16, B.R18, B.B8, B.R22, and B.N1) wereselected to evaluate the lysis capacity against A. hydrophila in tap and river water for 21 days in vitro. The results revealed that the bacteriophages could survive better in river water than in tap water. All six phages could be utilized to investigate the effectiveness of treating A. hydrophila-caused hemorrhagic disease in catfish in vivo.