Intestinal function and gut microflora of broiler chickens as influenced by cereal grains and microbial enzyme supplementation

A study was conducted to investigate the effect of the key cereal grains and a microbial enzyme supplement on broiler chicken performance, gut microflora and intestinal function. Ingestion of the barley-based diet was associated with low 28-day body weight, decreased feed intake and high FCR. The supplemental enzyme increased feed intake and weight gain of the chickens on a wheat-based diet. The pH of the gizzard and caecal contents varied with the grain type. Enzyme supplementation reduced ileal viscosity, particularly in birds that received the diet based on wheat. The birds on the barley-based diet had lower ileal digestibility of dry matter, protein and energy than those given maize and sorghum-based diets. The ileal digestibility of starch was increased by enzyme supplementation. Enzyme supplementation increased the number of total anaerobic bacteria in the gizzard of birds fed on sorghum and increased lactobacilli in the gizzard of those fed both sorghum and wheat. The birds fed the sorghum-based diet had the lowest counts of caecal total anaerobic bacteria and lactobacilli. Jejunal villus height and villus:crypt ratio of birds fed the barley-based diet were the lowest when compared with those fed the other diets. Enzyme application induced an increase in villus height and villus:crypt ratio of birds on wheat, crypt depth on barley and a reduction in crypt depth of chickens on the sorghum-based diets. The highest activity of maltase and the lowest activity of sucrase were observed in tissue from birds fed on maize and sorghum-based diets respectively. The differences in the performance of broilers on cereal grains could be explained by changes in intestinal morphology, enzyme activities and gut microflora as well as nutrient digestibility. The improved performance by supplemental enzyme in wheat-fed chickens was associated with beneficial changes in intestinal morphology and digesta viscosity.     

Whole blood and plasma viscosity values in normal and ascitic broiler chickens.

1. Whole blood and plasma viscosity values in normal and ascitic broiler chickens were measured. 2. The mean blood viscosity value in ascitic broilers was greater than that of the controls. There was a small but significant difference in the opposite direction between plasma viscosity values of the respective groups of birds. 3. Although the haematocrit and arterial pressure index values in the ascitic birds were raised, there was a fall in the concentration of total plasma protein. 4. The data suggest that the raised viscosity in the ascitic birds was caused by a polycythemia and not by any influence of plasma protein. 5. The cumulative effect of these factors, such as raised blood viscosity values and larger deformed red cells flowing through constricted lung arterioles, may contribute to the pulmonary hypertension and ascites seen in some young commercial broilers.     

肉仔鸡肠道微生物的日粮调控——六类饲用抗生素替代品的作用

早在1986年瑞典就率先提出了禁止在肉鸡饲料中使用抗生素,随后抗生素的禁用在世界各地全面展开,自此以来抗生素替代品的研究在动物营养中已受到了越来越多的关注。肠道微生物似乎是饲用抗生素(In-Feed Antibiotics,IFAs)的作用对象,同时抗生素替代品必须有利于维持动物健康和具有一定的促生长作用。本文讨论了六种饲用抗生素替代品对肠道微生物菌群的作用,综述了它们的作用机制和促生长作用,并重点介绍最近几年多位作者以甘露寡糖为抗生素替代品的研究结果。     

Pre-caecal digestible phosphorus in maize and wheat for broiler chickens

1. The objective of this study was to determine the coefficient of pre-caecal digestion of P in maize (3.9 g/kg of total P, 0.83 g/kg of phytate P, 138 FTU [phytase units]/kg) and wheat (3.17 g/kg of total P, 1.94 g/kg of phytate P, 666 FTU/kg) in broilers according to the WPSA protocol.

2. For the diets, monosodium phosphate was used as an additional P supplement. Two sets of diets containing 200, 460 and 740 g/kg of wheat or 200, 500 and 740 g/kg of maize were formulated. A total of 288 21-d-old male broilers (Ross 308) were assigned to 24 cages (8 birds per cage) and the 6 test diets were assigned to cages. The coefficient of pre-caecal digestion of P was determined by the indicator method and linear regression.

3. In both ingredients, pre-caecal digestible P increased linearly with increasing inclusion levels of maize or wheat (P < 0.05). The coefficients of digestion of pre-caecal P were estimated to be 0.18 for wheat and 0.33 for maize.     

Effect of different concentrations of Bacillus subtilis on growth performance, carcase quality, gut microflora and immune response of broiler chickens

1. An experiment was conducted to study the effects of different Bacillus subtilis concentrations on productivity, carcase quality, immune response and the gut microflora of broiler chickens. 2. There were 5 treatment groups: control, with no added Bacillus subtilis supplementation; and 4 treatment groups receiving feed supplemented with different concentrations of B. subtilis. 3. Weight gain was significantly higher and the feed conversion rate was significantly better in all groups receiving feed supplemented with B. subtilis, regardless of its concentration. The groups given B. subtilis supplementation produced relatively bigger breasts, and smaller carcases and thighs, compared with the control group. 4. The appearance of increased diffuse lymphohistiocytic infiltration and solitary lymphoid follicles in the mucosa, and a stronger response to NDV vaccination, indicate increased immunological responses in chickens fed with the B. subtilis supplemented diet. 5. The higher inclusion rate of B. subtilis did not increase Lactobacillus concentrations in the ileum or in the caecum, but decreased the E. coli population significantly.     

Characterisation and response of intestinal microflora and mucins to manno-oligosaccharide and antibiotic supplementation in broiler chickens

1. An experiment was conducted to characterise and evaluate, in comparison to zinc bacitracin (ZnB), the response of intestinal microflora and mucins to manno-oligosacchares (MOS, Bio-MOS®, Alltech Biotechnology, Nicholasville, Kentucky, USA).

2. Supplementation of MOS and ZnB selectively increased the intensity of sulphomucins. As revealed by the plate culture method, MOS accelerated the maturation of gut microflora by promoting the growth of lactobacilli in the ileal mucosa and vice versa on ileal and caecal clostridia. Unlike MOS, ZnB suppressed the growth of intestinal bacteria, especially those of lactobacilli and clostridia. Use of T-RFLP further revealed that MOS increased the diversity of lactobacilli in the ileum and ileal mucosa but the opposite was observed for ZnB. It also appears that MOS and ZnB possessed a common property in differentially favouring the growth of certain Lactobacillus species. There was also evidence to show that both MOS and ZnB also increased the homogeneity of the gut microflora, possibly through the regulation of the overall gut bacterial communities.

3. Improvement in intestinal microbial homogeneity and mucin synthesis, coupled with the differential selections for certain specific beneficial bacterial species, may ultimately be proven to be the target mechanisms in the search for more effective alternatives to antibiotics.     

Chemical composition and the nutritive quality of different wheat cultivars for broiler chickens

1. Different wheat cultivar samples were grown in replicated trials on a single site in three harvest years. A total of 23 wheat samples were harvested. Nutritionally complete, meal-form diets that included each wheat sample at 650 g/kg were used to compare broiler growth performance and determine apparent metabolisable energy (AME). The relationships were examined between these variables of nutritive value for broilers and the chemical composition and tests of quality on the wheat samples. 2. The total starch contents of the wheat samples ranged from 594 to 732 g/kg dry matter (DM). The mean total non-starch polysaccharide (NSP) content was 100g/kg DM comprising 73.5 g/kg DM of insoluble material. Endosperm hardness ranged between 10 and 77 relative units and Beaver was the softest cultivar in two of the batches of samples. The AME of the wheat-based diets had a maximum range of 0.5 MJ/kg within each of the three batches of wheat that were tested. 3. Endosperm hardness of the wheat grains, within a harvest year, was positively correlated with broiler weight gain and the 1000-grain weight was negatively correlated with feed conversion efficiency (FCE). Starch content and gross energy were positively correlated with determined AME, and DM, 1000-grain weight and water holding capacity were negatively correlated with AME. 4. A step-wise regression technique indicated that endosperm hardness and ash content of the wheat were the explanatory variables that, within harvest years, significantly reduced the unexplained variation in broiler growth rate, feed intake and FCE. The contents of total starch, crude protein and ether extract were the explanatory variables that, within harvest years, significantly reduced the unexplained variation in AME.     

Effect of oat hulls on performance, gut capacity and feed passage time in broiler chickens

1. Two experiments were conducted to study effects of oat hulls and their interaction with soluble fibre in broiler chickens. 2. In experiment 1, wheat or naked oats based diets with or without NSP-degrading enzymes were mixed with 0, 40 or 100 g/kg oat hulls which replaced a maize starch/soy isolate mixture, and the diets were fed to broiler chickens from 7-21 d of age. 3. Production results, AMEn determined between 14 and 16 d of age, and ileal digestibility indicated no negative effect of oat hulls on nutrient digestibility or weight gain. 4. Feed consumption increased significantly when oat hulls were included in the diet and relative gut weight increased correspondingly (P<0.05). 5. No interaction effects were found between soluble and insoluble fibres, except for a possible effect on starch digestibility in wheat diets. 6. In experiment 2, mash diets were fed unsupplemented, or were supplemented with coarsely or finely ground oat hulls which replaced a maize starch/soy isolate mixture. 7. Faecal titanium dioxide excreted between 1 and 48 h after feeding of a gelatin capsule containing titanium dioxide, was used to calculate feed passage time. 8. There was a tendency (P=0.08) for faster feed passage with inclusion of coarsely ground oat hulls, but no effect of finely ground oat hulls was found.     

Influence of dietary mushroom Agaricus bisporus on intestinal morphology and microflora composition in broiler chickens

In this study, we evaluated the intestinal morphology and bacteria populations in broiler chickens fed for six weeks diets that contained different amount of the mushroom Agaricus bisporus. Ninety day-old female chicks were randomly divided into three dietary treatments, each with three replicates kept in floor pens and fed a basal diet supplemented with the dried mushroom at levels of 0, 10 or 20 g/kg fresh feed. Feed and water were offered to birds ad libitum. The morphological examinations of the intestine were carried out on 1-cm long excised segments from duodenum, jejunum and ileum. The populations of total aerobes, total anaerobes, Lactobacilli spp., Bifidobacteria spp., Escherichiacoli, Bacteroides spp. and Enterococci were enumerated in ileum and caecum by conventional microbiological techniques using selective agar media. The results of the study showed that dietary mushroom supplementation did not significantly affect intestinal morphology at either level of inclusion. Morphometrical parameters of depth of duodenum, jejunum and ileum crypt and height of villi revealed no differences amongst dietary treatments. In the ileum, Lactobacilli spp. were higher in birds supplemented at the level of 20 g/kg compared to controls; however, other measurements of bacteria loads were similar amongst the three dietary treatments. In the caecum, Lactobacilli spp. and Bifidobacteria spp. loads were higher in birds supplemented at either level of inclusion compared to control birds, although these did not differ between the two levels of supplementation. In conclusion, dietary mushroom supplementation may beneficially affect intestinal health of broiler chickens.     

Proventriculitis in broiler chickens: effects of immunosuppression

Proventriculitis in broilers causes carcass condemnation when swollen proventriculi tear during evisceration. The cause of this proventriculitis is unknown, but several infectious agents have been associated with it. One such agent, infectious bursal disease virus (IBDV), has been implicated as a cause of proventriculitis, but a direct effect of this virus on the proventriculus has not been proven. The role of IBDV in proventriculitis may be indirect as a result of its ability to cause immunosuppression. The objective of this study was to understand how immunosuppression affects the incidence of proventriculitis in broiler chickens. Immunosuppression was induced in commercial and specific-pathogen-free broiler chickens using chemicals (cyclophosphamide and cyclosporin) or virus (IBDV). All groups were then exposed to a proventricular homogenate produced from diseased birds. At 7 and 14 days postinoculation, the incidence of proventriculitis in these groups was compared to that produced by homogenate exposure in immunocompetent broilers. All birds exposed to the proventricular homogenate from diseased birds developed proventriculitis. Cyclophosphamide and IBDV, both B cell suppressors, did not significantly affect the incidence or characteristics of the proventriculitis observed, although they did have an effect on the size of the proventriculus at 7 days postinoculation. Chickens immunosuppressed with cyclosporin, a T cell suppressor, developed more severe lesions and had a higher incidence of proventriculitis. These findings indicate that both B and T cells are involved in the immune response against proventriculitis, but cell-mediated immunity appears to have a more important role in controlling the disease. IBDV affects both humoral and cellular immunity in the chicken, so although under experimental conditions it didn't have a major effect on proventriculitis, it may explain why control of IBDV in the field seems to reduce the incidence of proventriculitis.     

Effect of whole and demucilaged linseed in broiler chicken diets on digesta viscosity,nutrient utilisation and intestinal microflora

1. A study was undertaken to evaluate the effects of the inclusion of linseed or demucilaged linseed in the diet on the performance, fat and fatty acid digestibilities, metabolisability of gross energy and intestinal microflora. 2. The dietary inclusions were 80 and 160 g/kg for linseed and 160 g/kg for demucilaged linseed. Diets were given to chickens from 1 to 23 d of age. 3. Incorporation of linseed in the diet, particularly at 160 g/kg, depressed weight gain and food utilisation. Digestibility of fat and single fatty acids and dietary metabolisable energy were reduced. 4. Inclusion of linseed in the diet markedly increased the viscosity of ileal digesta. Microbial activity in the ileum and caeca was not greatly affected, but there was a significant increase in the number of lactobacilli. 5. The antinutritional effects caused by feeding linseed were partially overcome by substituting demucilaged linseed for linseed in the diet. 6. Results from the current study suggest that the viscous properties of mucilage are a major factor in the observed antinutritional effects of linseed through increasing intestinal viscosity. Such effects might also be mediated by the gut microflora.     

Prophylactic and therapeutic treatment of ascites in broiler chickens.

1. This work examined the effect of using three different feeding regimens in the prophylaxis and treatment of ascites in fastgrowing broilers stressed by exposure to cold (less than 10 degrees C), itself a potent inducer of ascites. 2. Broilers were exposed to cold in tiered cages in a semi-open poultry shed from the age of 24, 29 or 34 d and from day 35 they were given one of three types of food (pellets, pellets with high energy content, mash). Total mortality and mortality with ascites were recorded and erythrocyte packed cell volume (PCV) and relative weight of the right ventricle were measured (both reliable indices of ascites development). 3. Despite relatively low ambient temperatures and consequent high mortality from ascites, the mash diet was effective both in preventing ascites (prophylaxis) and in treating existing ascites.     

Novel probiotics: Their effects on growth performance,gut development,microbial community and activity of broiler chickens

A total of 294 one-day-old Cobb broiler chickens were used to investigate the effects of four Lactobacillus strains on gut microbial profile and production performance. The six dietary treatments, each with 7 replicates were: 1) basal diet(negative control), 2) one of four strains of Lactobacillus(tentatively identified as Lactobacillus johnsonii, Lactobacillus crispatus, Lactobacillus salivarius and an unidentified Lactobacillus sp.) and 3) basal diet with added zinc-bacitracin(ZnB, 50 mg/kg). Results showed that the addition of probiotic Lactobacillus spp. to the feed did not significantly improve weight gain, feed intake and feed conversion rate(FCR) of broiler chickens raised in cages during the 6-week experimental period,but tended to increase the number of total anaerobic bacteria in the ileum and caeca, and the number of lactic acid bacteria and lactobacilli in the caeca; and to significantly increase the small intestinal weight(jejunum and ileum). Furthermore, all 4 probiotics tended to reduce the number of Enterobacteria in the ileum, compared with the control treatments. The probiotics did not affect the p H and the concentrations of short chain fatty acids(SCFA) and lactic acid in both the ileum and caeca.     

The development of tibial dyschondroplasia in broiler chickens.

Two strains of broiler chickens selected for a high and a low incidence of tibial dyschondroplasia were fed a standard broiler starter ration with and without added chloride. Development of tibial dyschondroplasia was studied by radiography and serial necropsies. Lesions of tibial dyschondroplasia were mild in the low-incidence strain, regardless of ratio. The defect was more severe in the high-incidence strain and most severe in those birds fed the high-chloride ration. An abnormal thickening of the growth plate was apparent in the high-incidence strain as early as 2 weeks of age and became progressively more severe with age. No significant differences were noted in serum calcium, phosphorus, alkaline phosphatase, pCO2, or bone ash between strains of birds or between birds of the same strain fed different rations. Birds fed the high-chloride ration had a higher serum chloride and a lower serum bicarbonate and blood pH than birds on the standard ration.     

Effect of carprofen on lameness in broiler chickens.

Lameness is prevalent among broiler chickens and there is concern that it is chronically painful. The administration of an analgesic has been frequently used to identify pain in lame farm animals. Therefore, in this study the ability of lame and normal broiler chickens to traverse an obstacle course was tested after treatment with the analgesic, carprofen, a placebo saline injection or a control handling procedure. Sound birds traversed the course in approximately 11 seconds, irrespective of treatment. Lame birds took approximately 34 seconds to traverse the course, unless they received carprofen, which reduced their completion time to 18 seconds. Thus, carprofen substantially increased the speed of lame birds, providing evidence that birds with moderate lameness suffer pain when they walk.     

Effects of food and water withdrawal and high temperature exposure on diurnal variation in blood viscosity of broiler chickens

1. Three experiments were conducted to investigate the diurnal variation of blood viscosity in broilers. In experiment 1 food and water were supplied freely at 20C (20-FW). In experiment 2 food and water were withdrawn at 20C (20-NFW), while in experiment 3 food and water were withdrawn at 30C (30-NFW). 2. Blood sampling time points were 09.00 h, 15.00 h, 21.00 h, 03.00 h and 09.00 h the next day in each experiment. 3. In all experiments, whole blood viscosity (WBV), red blood cell count (RBC) and haematocrit (HCT) were greater during the dark (21.00 h and 03.00 h) than during the light period. During the dark period, there were no differences in WBV, RBC and HCT between 20-FW and 20-NFW, or between 20-NFW and 30-NFW. At 09.00 h, WBV and HCT were higher in 20-FW than in 20-NFW. At 15.00 h and 09.00 h (day 2), WBV and HCT were greater in 20-NFW than in 30-NFW. 4. There were no light-dark differences in plasma viscosity (PV), plasma protein concentration (PPC) or mean corpuscular volume (MCV) in any experiment. However, 20-NFW birds had a lower PPC and higher MCV compared with 20-FW, and a higher PPC and lower MCV compared with 30-NFW, while no difference was found in PV. 5. WBV increased linearly with RBC and HCT. PV increased with PPC, while MCV decreased. 6. These results indicate that there is diurnal variation in whole blood viscosity, which is greater during the dark than during the light period. During the light period it is strongly influenced by high environmental temperature and food and water withdrawal. C     

Pharmacokinetics of tylosin in broiler chickens

Biological availability and pharmacokinetic properties of tylosin were determined in broiler chickens after oral (p.o.) and intravenous (i.v.) administration at a dose of 10 mg/kg. The calculated bioavailability--F%, by comparing AUC values--p.o. and AUC--i.v., ranged from 30%-34%. After intravenous injection tylosin was rapidly distributed in the organism, showing elimination half-life (t1/2 beta) values of 0.52 h and distribution volume (Vd) of 0.69 L/kg, at a clearance rate (Cl) of 5.30 +/- 0.59 ml/min/kg. After oral administration, tylosin has a similar distribution volume (Vd = 0.85 L/kg), while the elimination half-life t1/2 beta of 2.07 h was four times bigger than after i.v. administration at Cl = 4.40 +/- 0.27 ml/min/kg. The obtained value tmax = 1.5 h for tylosin after oral administration indicates that using this antibiotic with drinking water in broiler chickens is the method of choice. However, a relatively low value Cmax = 1.2 micrograms/ml after oral administration of tylosin shows that dosing of this antibiotic in broiler chickens should be higher than in other food producing animals.