Intracloacal Salmonella typhimurium infection of broiler chickens: reduction of colonization with anaerobic organisms and dietary lactose

The combined effect of treatments with dietary lactose plus anaerobic organisms on cecal colonization of broiler chicks by Salmonella typhimurium was evaluated. Chickens treated with a combination of anaerobic organisms and 7% dietary lactose were resistant to cecal colonization by S. typhimurium. The number of recoverable S. typhimurium cells per gram of cecal contents taken on days 10 and 15 after infection was significantly reduced. Treatment with anaerobes without the addition of lactose did not effectively control cecal colonization. Intracloacal inoculations with bacterial concentrations that varied by 10,000-fold resulted in roughly similar levels of colonization. The treatments resulted in reduced cecal pH and elevated levels of undissociated volatile fatty acids. Statistically significant correlations (P less than 0.01) were observed between the S. typhimurium concentrations in cecal material and the concentrations of undissociated fatty acids (r = -0.79, and between the bacterial counts and pH (r = 0.72).     

Effect of carbohydrates on Salmonella typhimurium colonization in broiler chickens

The effect of carbohydrates in the drinking water of broiler chickens on Salmonella typhimurium colonization was evaluated. Results indicate that mannose and lactose (2.5%) significantly (P less than 0.05) reduced intestinal colonization of S. typhimurium by at least one-half, as compared with dextrose, maltose, and sucrose. Lactose and mannose also significantly reduced (P less than 0.01) the mean log10 number of S. typhimurium in the cecal contents. Although mannose was the most effective sugar at blocking colonization, lactose may be more practical because it is effective and costs much less than mannose. Provision of carbohydrates in the drinking water had no significant effect on weight gain.     

Colonization control of lactose-fermenting Salmonella typhimurium in young broiler chickens by use of dietary lactose

Inclusion of lactose in the diets of chickens has been determined to reduce cecal colonization with Salmonella typhimurium. We hypothesized, therefore, that dietary lactose may be a practical means for reducing the prevalence of Salmonella contamination of chicken products. Because some strains of Salmonella are atypical and ferment lactose, we investigated the effects of dietary lactose on cecal colonization with lactose-fermenting S typhimurium. Broiler chicks were inoculated intracloacally with Lac+ S typhimurium selected for resistance to novobiocin and rifampicin. The chicks also were inoculated orally with certain anaerobes that do not effectively inhibit colonization by S typhimurium, but do appear essential for lactose mediated inhibition of cecal colonization. Control chicks were not given dietary lactose, and chicks in the experimental group were fed a diet containing 7% lactose. Enumeration of Lac+ S typhimurium in cecal contents revealed dietary lactose to be effective at controlling this organism. Control was correlated with changes in cecal pH and increases in undissociated volatile fatty acids, especially propionic acid.     

Effect of dietary lactose on cecal pH, bacteriostatic volatile fatty acids, and Salmonella typhimurium colonization of broiler chicks

One-day-old broiler chicks were inoculated with volatile fatty acid producing cecal flora from adult chickens. The chicks were divided into four groups and provided 1) no lactose, 2) 2.5% lactose in water, 3) 5% lactose in feed, or 4) 10% lactose in feed, until 10 days of age. All groups were challenged at 3 days of age with 10(6) or 10(8) S. typhimurium. At 10 days, the number of Salmonella in the ceca of the chicks challenged with 10(6) Salmonella was significantly decreased (P less than 0.01) in the groups provided lactose as compared with the controls. A significant decrease (P less than 0.01) in Salmonella numbers occurred in the chicks challenged with 10(8) Salmonella and provided 10% lactose. Providing 2.5% lactose or 5% lactose failed to inhibit Salmonella growth in chicks challenged with 10(8) Salmonella. The pH of the ceca of the groups provided lactose decreased significantly (P less than 0.05) and was accompanied by significant increases (P less than 0.01) in the concentrations of bacteriostatic acetic and propionic acids. Results showed that providing dietary lactose to broiler chicks and inoculation with normal cecal flora decreased cecal pH, increased the concentrations of bacteriostatic volatile fatty acids, and inhibited Salmonella colonization.     

Effect of anaerobic cecal microflora and dietary lactose on colonization resistance of layer chicks to invasive Salmonella enteritidis.

The effect of oral inoculation with anaerobic cultures of cecal microflora and providing lactose in the feed on colonization resistance to invasive Salmonella enteritidis was evaluated in newly hatched leghorn chicks. Salmonella colonization of the ceca, tissue invasion and organ colonization, horizontal transmission, and seroconversion were significantly decreased (P less than 0.01) in chicks inoculated with cecal flora. The addition of lactose to the feed, in the absence of cecal microflora, failed to provide protection. Dietary lactose enhanced colonization resistance in chicks that were inoculated with anaerobic cultures of cecal flora. The results indicated that establishment of normal cecal flora in layer chicks together with the addition of lactose to the diet markedly increases resistance to cecal colonization and organ invasion, and decreases horizontal transmission of S. enteritidis.     

The effects of a competitive exclusion product and two probiotics on Salmonella colonization and nutrient digestibility in broiler chickens

Competitive exclusion (CE) cultures, given as a single dose on the day of hatch, together with good hygienic practices has been shown to be a novel approach to control Salmonella in poultry. The ability of the CE product Broilact and 2 probiotics, FloraMax-B11 and Colostrum, to prevent Salmonella colonization in newly hatched chickens was evaluated employing a slightly modified Mead-model chicken assay. In a parallel study the effect of the 3 treatments on the production of volatile fatty acids in the ceca were determined. In the Salmonella study 2 separate experiments were done. In the first experiment all 3 treatment materials were given as a single dose on d 1. In the second experiment, which consisted only of Broilact and FloraMax-B11, the latter was given in the drinking water during the 3 first d after hatch. In both experiments the chicks were challenged with Salmonella enterica serovar Infantis on d 2. The results of the present study show that Broilact was superior to the 2 other treatment materials in protecting the newly hatched chickens against Salmonella colonization. The parallel study showed only minor differences among the different treatments. Based on the results of the Salmonella challenge study, it was concluded that Broilact was the only treatment material that was established in the gut of the newly hatched chickens in such a way that the colonization of Salmonella was prohibited.     

Comparison of prophylactic or therapeutic dietary administration of capsaicin for reduction of Salmonella in broiler chickens

In three experiments the effects of prophylactic or therapeutic dietary inclusion of capsaicin, the pungent component of peppers, were evaluated as a nonantibiotic alternative for reduction of Salmonella in broiler chickens through culture and morphologic assessment of cecal tissue. Expt. 1 evaluated the effects of 0 or 10 ppm purified capsaicin (CAP) in the starter phase (days 1-16) on chicks challenged with Salmonella Enteritidis (SE) on day of age. Therapeutic inclusion of 10 ppm purified CAP increased (P < 0.05) liver/spleen (L/S) and ceca positive results for SE. In Expt. 2, capsaicin oleoresin (CO) was included in the finisher diet (days 30-37) at 0, 5, or 20 ppm with SE challenge on day 31. Inclusion of 5 ppm CO increased ceca positive results for SE, and a linear decrease in cecal lamina propria thickness of SE-challenged birds was observed with increased CO concentration in the diet. Expt. 3 evaluated prophylactic CO treatment at 0, 5, or 20 ppm in starter, grower, and finisher diets for resistance to SE or Salmonella Typhimurium (ST) challenge on day 14 or 29. With challenge on day 14, 5 and 20 ppm prophylactic CO feeding reduced ceca SE positive results by 37% and 26%, respectively, and ST culture rate was reduced similarly with 5 ppm CO. Lamina propria thickness of the ceca increased with 5 ppm CO feeding in SE-challenged birds, whereas a decrease was observed in nonchallenged birds fed 5 ppm CO. Challenge on day 29 of birds fed 20 ppm CO resulted in reduced L/S positive results for SE. Lamina propria thickness decreased with 5 ppm CO and SE or ST challenge compared with nonchallenged birds fed 5 ppm. An increase was observed in ST- or SE-challenged birds fed 20 ppm CO compared with nonchallenged birds fed 20 ppm CO. No differences were observed in mast cell number in either Expt. 2 or 3. These data provide evidence that prophylactic or therapeutic dietary capsaisin differentially affects broiler susceptibility to Salmonella.     

预消化处理肉鸡加酶日粮中非淀粉多糖酶解效果的研究

文章旨在研究4种单体NSP酶制剂(木聚糖酶、β-葡聚糖酶、纤维素酶和甘露聚糖酶),经过预消化处理工艺后,对肉鸡日粮中的非淀粉多糖的酶解情况,为进一步研究NSP酶制剂在肉鸡日粮中的合理利用提供参考依据。结果显示,不同的NSP酶添加量对肉鸡日粮的预消化处理效果有着显著的相关关系,木聚糖酶、β-葡聚糖酶、纤维素酶、甘露聚糖酶的最佳添加水平分别为250、350、300、200 mg/kg;初步确定的预消化处理参数是:温度45℃、时间60 min、水分35%。本试验条件下,结合相关的数据分析,试验日粮中最佳酶制剂组合是:木聚糖酶186 mg/kg、β-葡聚糖酶440 mg/kg、纤维素酶337 mg/kg、甘露聚糖酶200 mg/kg(P<0.01)。研究表明,加酶日粮经过预消化处理后,可以有效地降解其中日粮的非淀粉多糖,提高日粮的营养利用率。     

Bacteriophage treatment reduces Salmonella colonization of infected chickens

Three different lyric bacteriophages (BPs) were isolated from the sewage system of commercial chicken flocks and used to reduce Salmonella Enteritidis (SE) colonization from experimental chickens. Ten-day-old chickens were challenged with 9.6 x 10(5) colony-forming units (CFU)/ml of a SE strain and treated by coarse spray or drinking water with a cocktail of the three phages at a multiplicity of infection (MO1) of 10(3) plaque-forming units (PFU) 24 hr prior to SE challenge. Chickens were euthanatized at day 20 of age for individual SE detection, quantitative bacteriology, and phage isolation from the intestine and from a pool of organs. SE detection was performed by both bacteriologic culture and genome detection by polymerase chain reaction (PCR). Qualitative bacteriology showed that aerosol-spray delivery of BPs significantly reduced the incidence of SE infection in the chicken group (P = 0.0084) to 72.7% as compared with the control group (100%). In addition, SE counts showed that phage delivery both by coarse spray and drinking water reduced the intestinal SE colonization (P < 0.01; P < 0.05, respectively). BPs were isolated at 10 days postinfection from the intestine and from pools of organs from BP-treated chickens. We conclude that the phage treatment, either by aerosol spray or drinking water, may be a plausible alternative to antibiotics for the reduction of Salmonella infection in poultry.     

Effect of dietary selenium on the development of Fusarium-induced tibial dyschondroplasia in broiler chickens

A trial was conducted to determine the effects of dietary level of selenium on the pathogenesis of Fusarium-induced tibial dyschondroplasia (FITD) in broiler chicks, and to assess the applicability of FITD as an animal model of Kashin-Beck disease of humans. Day-old female broilers were fed diets that were deficient in selenium (0.02 ppm Se), adequate in selenium (0.15 ppm Se), or generous in selenium (0.50 ppm Se). TDP-1, the toxic component of the fungus, was administered to 15 of 26 chicks in each dietary group starting at 1 week of age and continuing until the chicks were killed at 24-30 days of age. Plasma selenium levels and hepatic glutathione peroxidase activity were significantly lower in the selenium-deficient group than in other dietary groups; these parameters were not affected by treatment with TDP-1. The mortality rate of the TDP-1-treated selenium-generous group was significantly less than that in the other TDP-1-treated groups, but there were no differences in the incidence, severity, or character of the FITD lesions among the groups. Thus, the interaction of selenium and TDP-1 did not include an effect on FITD.     

Effect of acidified feed on the prevalence of Salmonella in market-age pigs

Two trials were carried out to determine the effect of feed acidification upon Salmonella carriage in market-age pigs. In the first trial, the administration for the last 14 weeks of the fattening period of a commercial pelleted feed added with 0.6% lactic acid plus 0.6% formic acid (Lac-Formic-1.2) was compared to an unacidified standard diet (STD). A second experiment was carried out in two herds of growing pigs (Herd I, 3000 pigs; Herd II, 900 pigs) in which three different diets were assayed during the last 8-9 weeks of the fattening period: a diet containing 0.8% formic acid (Formic-0.8), a diet containing 0.4% lactic acid plus 0.4% formic acid (Lac-Formic-0.8) and a STD. In the first experiment, serological evolution of the infection was examined by ELISA and microbiological cultures (rectal samples and mesenteric lymph nodes) were also done. Feed intake by pen and the individual weight of the animals were also measured. In the second trial, blood, rectal samples and mesenteric lymph nodes were collected at slaughter in both herds (30 pigs per experimental group). In the first experiment, the acidified diet (Lac-Formic-1.2) reduced Salmonella carriers in mesenteric lymph nodes (Fisher's exact P < 0.01). In the second trial, Lac-Formic-0.8 diet significantly reduced Salmonella seroprevalence compared to the STD (P = 0.001) in both herds. Also Lac-Formic-0.8 and Formic-0.8 diets in Herd II showed a lower faecal excretion and Salmonella carriage in mesenteric lymph nodes than the STD (P < 0.05). Our results suggest that the administration of a combination of lactic and formic acids at the levels used in this study could be used to reduce Salmonella prevalence in finishing pigs.     

Effect of dietary phosphorus concentration and electrolyte balance on the growth performance of broiler chickens

The performance of 1680 male and female broiler chickens given diets with either a low (4.7-4.3 g/kg) or high (8.9-8.2 g/kg) content of inorganic phosphorus and four (150, 200, 250 and 300 mEq/kg) electrolyte balances (Na+K-Cl) was measured from 1-d-old to 49 d of age. Diets with the higher concentration of inorganic phosphorus reduced body weight gains in the starter (P less than 0.01) and finisher (P less than 0.05) phases but the efficiency of food utilisation was reduced only in the starter phase (P less than 0.05). The reduction in body weight gain was greater in males than in females. The growth depression caused by the higher concentration of inorganic phosphorus in the finisher diets was partially alleviated by increasing the electrolyte balance to either 250 or 300 mEq/kg diet. The higher concentration of inorganic phosphorus significantly reduced the dressing percentage and increased the abdominal fat pad weight and litter moisture content. Electrolyte balance had no significant effects on efficiency of food utilisation, abdominal fat pad weights or litter moisture content. Neither the dietary concentration of phosphorus nor the electrolyte balance had a significant effect on mortality or ash content of the tibia.     

Effect of dietary fibres on small intestine histomorphology and lipid metabolism in young broiler chickens

Two experiments were conducted to determine the influence of dietary fibres on small intestine histomorphology and lipid metabolism in broilers from 1 to 21 day of age. In experiment 1, diets containing insoluble [cellulose (CEL); 2% and 4%] or soluble [carboxymethyl cellulose (CMC); 2% and 4%] fibre were fed to broilers from day 1 to 21 post‐hatch and ileal tissue was collected at day 21 of age for histological evaluation. In experiment 2, broilers diet was supplemented with 0%, 1% or 2% insoluble fibre (Arbocel) during day 7 to 21 post‐hatch and plasma and liver lipid metabolism were evaluated at day 21. In experiment 1, inclusion of CMC reduced body weight gain (BWG) and feed intake (FI) and increased feed conversion ratio (FCR) compared with others. Intestinal histomorphology was unaffected by CEL, but CMC led to an increase in crypt depth (CD) and serosa thickness and a decrease in villus height (VH), villus width (VW), VH:CD ratio and villus surface area (VSA), rather than control and CEL groups. Treatment did not affect goblet cell type. Moreover, the CMC‐fed birds had greater total goblet cell count (GCC) as compared with others. In experiment 2, fibre inclusion was associated with increases in BWG from 7 to 14 day of age and an improvement in FCR, whereas FI was not influenced by treatments. Inclusion of fibre in the diet decreased the weight of the abdominal fat and cholesterol concentrations of liver and plasma. No significant effects on fatty acid composition of liver lipid were observed by fibre supplementation. These findings suggest dietary fibre affects performance, intestinal histomorphology and lipid metabolism in young chicks, which may directly affect poultry feeding strategies.     

Effect of immunosuppression with cyclophosphamide, cyclosporin, or dexamethasone on Salmonella colonization of broiler chicks

One-day-old broiler chicks were divided into four groups: untreated controls and three groups treated with the immunosuppressive drugs cyclophosphamide, cyclosporin, or dexamethasone on days 1-4 of age. On day 5, all groups were challenged orally with 10(4) Salmonella typhimurium. Suppression of immunocompetency was demonstrated in the treatment groups by significant decrease (P less than 0.05) in weights of bursas of Fabricius, and diminished mitogen-induced T and B lymphocyte blastogenesis and cutaneous basophil hypersensitivity responses. There were no significant differences among the four groups in the number of Salmonella in the cecal contents or in the number of cecal-culture-positive chicks on day 10 post-challenge at 15 days of age. Results indicated that impairment of B or T lymphocyte responses had little influence on the resistance of young chicks to Salmonella cecal colonization.