Bacillus subtilis-based direct-fed microbials augment macrophage function in broiler chickens

The present study was conducted to evaluate the function of Bacillus subtilis-based direct-fed microbials (DFMs) on macrophage functions, i.e., nitric oxide (NO) production and phagocytosis in broiler chickens. DFMs used in this study were eight single strains designated as Bs2084, LSSAO1, 3AP4, Bs18, 15AP4, 22CP1, Bs27, and Bs278, and one multiple strain DFM product (Avicorr™) containing equal amount of Bs2084, LSSAO1 and 15AP4. NO concentrations were monitored in plasma and in the supernatants from the peripheral blood-derived monocytic cells (PBMC)-derived macrophages stimulated by either chicken recombinant interferon gamma (IFNγ) or lipopolysaccharide (LPS) from Escherichia coli or Salmonella typhi. In addition, phagocytosis of fluorescent beads and green fluorescent protein (GFP)-labeled Salmonella by PBMC-derived macrophage was assayed. Plasma NO levels were significantly higher in groups given 3AP4 or Bs27 diets compared with the control group at days 7 and 14. NO production by PBMC-derived macrophages stimulated with IFNγ or LPS was apparent, although the effect was strain-dependent. Phagocytosis of fluorescent beads or GFP-labeled Salmonella by macrophages was augmented in groups on DFM-supplemented diets compared with those fed the control diet. This study describes the immunomodulatory effects of Bacillus-based DFMs on innate immunity in broiler chickens.     

Effect of Bacillus-based direct-fed microbials on Eimeria maxima infection in broiler chickens

The effect of dietary Bacillus-based direct-fed microbials (DFMs; eight single strains designated as Bs2084, LSSAO1, 3AP4, Bs18, 15AP4, 22CP1, Bs27, and Bs278, and one multiple-strain DFM product [AVICORR™]) on growth performance, intestinal lesions, and innate and acquired immunities were evaluated in broiler chickens following Eimeria maxima (EM) infection. EM-induced reduction of body weight gain and intestinal lesions were significantly decreased by addition of 15AP4 or Bs27 into broiler diets compared with EM-infected control birds. Serum nitric oxide levels were increased in infected chickens fed with Bs27, but lowered in those given Bs2084, LSSAO1, 3AP4 or 15AP4 compared with the infected controls. Recombinant coccidial antigen (3-1E)-stimulated spleen cell proliferation was increased in chickens given Bs27, 15AP4, LSSAO1, 3AP4, or Bs18, compared with the infected controls. Finally, all experimental diets increased concanavalin A-induced splenocyte mitogenesis in infected broilers compared with the nonsupplemented and infected controls. In summary, dietary Bacillus subtilis-based DFMs reduced the clinical signs of experimental avian coccidiosis and increased various parameters of immunity in broiler chickens in a strain-dependent manner.     

Effect ofBacillus amyloliquefaciens-based direct-fed microbials and antibiotic on performance,nutrient digestibility,cecal microflora,and intestinal morphology in broiler chickens

Two hundred eighty-eight 1-d-old male Arbor Acres broilers were randomly allocated to 4 treatments to examine the effect of usingBacillus amyloliquefaciens-based direct-fed microbials (DFM) to replace antibiotics in the late growth stage on performance, nutrient digestibility, cecal microflora, and intestinal morphology in broilers. The experimental diets were (1) a negative control (NC) group fed a basal diet without any antibiotics; (2) a positive control (PC) group fed the basal diet with 200 mg/kg of zinc bacitracin; (3) a test group fed the basal diet with 200 mg/kg of zinc bacitracin from d 1 to 21 and 30 mg/kg of DFM from d 22 to 42 (DFM30); and (4) a test group fed the basal diet with 200 mg/kg of zinc bacitracin from d 1 to 21 and 60 mg/kg of DFM from d 22 to 42 (DFM60). The results showed that DFM30 and DFM60 increased BW gain and improved FCR as compared with NC group (P < 0.05). Generally, the PC, DFM30, and DFM60 groups showed increased apparent total tract nutrient digestibility for DM, CP, and AME as compared with the NC group. Both the DFM30 and DFM60 groups decreased cecalEscherichia coli population as compared with the NC group, and increased the population ofLactobacillus as compared with the PC group. The PC, DFM30, and DFM60 groups increased villus height and the ratio of villus height to crypt depth compared with NC. In conclusion, dietary supplementation withB. amyloliquefaciens-based DFM during d 22 to 42 may enhance performance by increasing nutrient digestibility and improving intestinal health in birds fed diets supplemented with zinc bacitracin from d 1 to 21.     

Performance and cost-benefit improvements following supplementation with a combination of direct-fed microbials and enzymes to broiler chickens raised with or without ionophores

Increased resistance and loss of sensitivity to traditional anticoccidial agents, as well as interest in antibiotic-free rearing programs, has increased the interest in alternative control measures. Therefore, this study aimed to assess the effect of a DFM (direct fed microbial)/multi-enzyme product (DFM+XAP, providing 2,000 U/kg xylanase, 200 U/kg amylase, 4,000 U/kg protease and 75,000 cfu/g DFM) on broiler performance and profitability under 2 anticoccidial strategies (vaccination and traditional ionophore therapy). The study diets were 1) a nutritionally adequate control based on corn/soy/DDGS (PC), 2) a negative control reduced in energy and amino acids (NC), and 3) NC+DFM+XAP. Diets were divided into 2 subgroups, receiving either ionophores from 0 to 43 d (salinomycin 60 g/t) or a coccidial vaccine (Coccivac B) (6 treatments, n = 8, 50 male birds/n). Performance was recorded on d 22, 35 and 43. The net value of DFM+XAP inclusion was determined for all treatments. At d 43 reduced BWG and highest FCR were seen in NC birds, regardless of coccidiosis control (P < 0.05). Adding DFM+XAP significantly improved BWG and FCR by 5% (2,087 vs. 1,991 g/bird) and 6% (1.803 vs. 1.906), respectively. In birds receiving vaccine (P < 0.05), resulting in BWG (2,125 g/bird) and FCR (1.772) not statistically different to birds fed PC diets. Across anticoccidial strategies, adding DFM+XAP resulted in 3% BWG improvement (P < 0.05) as compared to NC. The net value of DFM+XAP addition, compared to PC, was $15.15/ton feed in vaccinated birds and $14.71 in those treated with ionophores. In conclusion, the addition of DFM+XAP to broiler diets significantly improved performance and profitability, regardless of coccidiosis control program, though response was likely to be greater in vaccinated birds.     

细菌类可直接饲用微生物在反刍动物上的应用及可能作用机制

可直接饲用微生物(DFM)在促进幼龄动物消化道发育、减少养殖动物消化道疾病、提高动物生产性能与产品品质,改善养殖环境方面均表现出令人满意的效果。随着国家政策和养殖模式的转变,以及饲用微生物应用理论与实践的积累,DFM在各类动物养殖中应用越来越普遍。目前在反刍动物中使用的DFM主要有真菌类如酵母及细菌类如乳酸菌、丙酸杆菌和芽孢杆菌等,文章就细菌类DFM在不同养殖阶段反刍动物上的饲喂效果及可能的作用机制进行了探讨,以期为该类添加剂在反刍动物中的更大范围推广与进一步研究提供部分理论参考。     

Bacterial direct-fed microbials fail to reduce methane emissions in primiparous lactating dairy cows

Direct-fed microbials(DFM) are considered as a promising technique to improve animal productivity without affecting animal health or harming the environment. The potential of three bacterial DFM to reduce methane(CH_4)emissions, modulate ruminal fermentation, milk production and composition of primiparous dairy cows was examined in this study. As previous reports have shown that DFM respond differently to different diets, two contrasting diets were used in this study. Eight lactating primiparous cows were randomly divided into two groups that were fed a corn silage-based, high-starch diet(HSD) or a grass silage-based, high-fiber diet(HFD). Cows in each dietary group were randomly assigned to four treatments in a 4 × 4 Latin square design. The bacterial DFM used were selected for their proven CH_4-reducing effect in vitro. Treatments included control(without DFM) and 3 DFM treatments: Propionibacterium freudenreichii 53-W(2.9 × 1010 colony forming units(CFU)/cow per day), Lactobacillus pentosus D31(3.6 × 1011 CFU/cow per day) and Lactobacillus bulgaricus D1(4.6 × 1010 CFU/cow per day). Each experimental period included 4 weeks of treatment and 1 week of wash-out, with measures performed in the fourth week of the treatment period. Enteric CH_4 emissions were measured during 3 consecutive days using respiration chambers. Rumen samples were collected for ruminal fermentation parameters and quantitative microbial analyses.Milk samples were collected for composition analysis. Body weight of cows were recorded at the end of each treatment period. Irrespective of diet, no mitigating effect of DFM was observed on CH_4 emissions in dairy cows. In contrast, Propionibacterium increased CH_4 intensity by 27%(g CH_4/kg milk) in cows fed HSD. There was no effect of DFM on other fermentation parameters and on bacterial, archaeal and protozoal numbers. Similarly, the effect of DFM on milk fatty acid composition was negligible. Propionibacterium and L. pentosus DFM tended to increase body weight gain with HSD. We conclude that, contrary to the effect previously observed in vitro, bacterial DFM Propionibacterium freudenreichii 53-W, Lactobacillus pentosus D31 and Lactobacillus bulgaricus D1 did not alter ruminal fermentation and failed to reduce CH_4 emissions in lactating primiparous cows fed high-starch or high-fiber diets.     

Evaluation of a Bacillus direct-fed microbial candidate on digesta viscosity,bacterial translocation,microbiota composition and bone mineralisation in broiler chickens fed on a rye-based diet

1. The effects of the dietary inclusion of a Bacillus-based direct-fed microbial (DFM) candidate on digesta viscosity, bacterial translocation, microbiota composition and bone mineralisation were evaluated in broilers consuming rye-based diets.

2. In the present study, control mash rye-based diets (CON) or Bacillus-DFM supplemented diets (TRT) were administered ad libitum to male broilers in three independent experiments.

3. In Experiments 1 and 2 (n = 25/group), liver samples were taken to evaluate bacterial translocation, digesta samples were used for viscosity measurements and the intestinal microbial flora was evaluated from different intestinal sections to enumerate total recovered gram-negative bacteria (TGB), lactic acid bacteria (LAB) and anaerobic bacteria (TAB). Additionally, both tibias were removed for assessment of bone quality.

4. In Experiment 3, each experimental group had 8 replicates of 20 chickens (n = 160/group). Weekly, body weight (BW), feed intake (FI) and feed conversion ratio (FCR) were evaluated. At d 28-of-age, samples were taken to determine bacterial translocation, digesta viscosity and bone quality characteristics.

5. In all experiments, consumption of Bacillus-DFM reduced bacterial translocation to the liver and digesta viscosity. Additionally, DFM supplementation improved BW, bone quality measurements and FCR. Moreover, chickens fed on the Bacillus-DFM diet in Experiments 1 and 2 showed a significant reduction in the number of gram-negative and anaerobic bacteria in the duodenal content compared to control.

6. In summary, chickens fed on a rye-based diet without DFM inclusion showed an increase in bacterial translocation and digesta viscosity, accompanied by reduced performance and bone quality variables relative to the Bacillus-DFM candidate group. Hence, incorporation into the feed of a selected DFM ameliorated the adverse anti-nutritional effects related to utilisation of rye-based diets in broilers chickens.     

Performance of broiler chickens supplemented with Bacillus coagulans as probiotic

1. A newly isolated Bacillus coagulans strain as probiotic was assayed as the only dietary additive for chickens. 2. Chickens receiving no additive at all or only virginiamycin were used for comparison. 3. Two trials each carried out on 75 chickens showed that, in terms of efficacy in growth and food conversion ratio, the B. coagulans biomass as a probiotic had a growth-promoting, prophylactic effect comparable to that of virginiamycin.     

Swollen-head syndrome in broiler chickens

Swollen-head syndrome is a disease seen in broiler chickens between 4 and 6 weeks of age in Southern Africa. It appears to be caused by a mixed coronavirus and Escherichia coli infection. The coronavirus appears to be of a hitherto unrecorded serotype. The disease is controlled by an attenuated live-virus vaccine and antibacterial medication.     

Salt poisoning in broiler chickens

The clinical signs of salt poisoning in young chickens are thirst, diarrhoea and weakness. When 13 500 broilers are simultaneously affected, the deterioration that occurs in their physical condition and in the litter beneath their feet is dramatic. Two flocks of meat chickens on a small unit in North Otago were affected in this way.     

Salt poisoning in broiler chickens

The incident occurred on a small, owner-operated broiler unit that used home-mixed feed. Two flocks of broilers, one aged 6 weeks and one aged 6 days, developed signs of watery diarrhoea, thirst and weakness. Over 3 days the mortality increased considerably and many birds were noticed to show laboured breathing. The majority of dead birds had an excess of clear fluid in the pericardial sac, oedematous lungs and pale swollen kidneys. Cystic dilation of the testes was conspicuous in several birds from the younger flock killed at 12 days of age. This lesion is a specific indication of sodium toxicity in young broilers. Histological lesions were those associated with cardiovascular collapse and hypoxia. Liver levels of sodium chloride were 4 g/kg of wet weight. Broiler feed samples contained more than 7% sodium chloride whereas the nutritional specifications were for 0.4%. The rations had been correctly mixed and the problem was traced to a faulty batch of meatmeal that had been contaminated by salt used for curing hides.     

Campylobacter succession in broiler chickens

The competitive ability of Campylobacter coli OR12 over C. jejuni OR1 has been examined in experimental broiler chickens following the observation that C. coli replaced an established C. jejuni intestinal colonisation within commercial chicken flocks reared outdoors [El-Shibiny, A., Connerton, P.L., Connerton, I.F., 2005. Enumeration and diversity of campylobacters and bacteriophages isolated during the rearing cycles of free-range and organic chickens. Appl. Environ. Microbiol. 71, 1259-1266]. Co-cultures of C. coli OR12 with C. jejuni OR1, revealed that the two species were able to grow together at similar growth rates in exponential growth phase but if the disparity of the inoculum ratios were >log(10)4 in favour of C. coli OR12, C. jejuni OR1 was observed to prematurely enter decline phase. Chickens were pre-colonised with C. jejuni OR1 at 21-days-old to examine succession in vivo. The birds were inoculated between 2 and 12 days later with C. coli OR12, to determine if the second isolate could efficiently colonise and compete with an established C. jejuni strain. C. coli OR12 were able to co-colonise before replacing C. jejuni OR1 as the dominant species when the birds were more than 27 days of age at the time of administration over a 4-day period. If these criteria were met C. coli OR12 became the dominant isolate otherwise co-colonisation occurred until they were met. C. coli OR12 was also found to displace three alternative C. jejuni strains from pre-colonised chickens challenged with C. coli OR12 at 30 days of age and tested at 40 days. These data raise the possibility of manipulating populations of Campylobacter colonising chickens through competition.     

Performance and digestive function of broiler chickens given grit in the diet

1. A series of experiments were carried out to study the effect of grit on broiler performance, gizzard development and fate of grit in the digestive tract.

2. In Experiment 1, performance, gizzard weight and content of grit in the gizzard of broiler chickens given access to granite-type grit was investigated. In Experiment 2, the effect of grit stones on performance and gizzard development was assessed in diets with or without whole wheat.

3. In Experiment 3, the effect of grit in the form of zeolite, granite or marble on gizzard development and digestive tract grinding and passage was studied in diets with or without whole wheat.

4. Grit stones had no effect on performance of broiler chickens, which may be explained by the fact that grit stones did not stimulate gizzard development to the same extent as with other structural materials.

5. The lack of stimulation is at least partly due to the fact that a majority of the grit stones eaten pass through the small intestine without being retained in the gizzard.

6. Grit in the form of marble reduced feed intake and weight gain.