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PubMed2005

Effects of drinking water treatment on susceptibility of laying hens to Salmonella enteritidis during forced molt.

Feed deprivation is used in the layer industry to induce molting and stimulate multiple egg-laying cycles in laying hens. Unfortunately, the stress involved increases susceptibility to Salmonella enteritidis (SE), the risk of SE-positive eggs, and incidence of SE in internal organs. Leghorn hens over 50 wk of age were divided into 4 treatment groups of 12 hens each in experiment 1 and 3 treatment groups of 12 hens in experiments 2 and 3; hens were placed in individual laying hen cages. Treatment groups were 1) nonmolted (NM) and received feed and distilled water for 9 d, 2) force molted by feed removal for 9 d and received distilled water, 3) force molted by feed removal for 9 d and received 0.5% lactic acid (LA) in distilled water. An additional group (4) in experiment 1 only was force molted by feed removal for 9 d and received 0.5% acetic acid in distilled water. Seven days before feed removal hens were exposed to an 8L:16D photoperiod, which was continued throughout the experiment. Individual hens among all treatments were challenged orally with 10(4) SE on d 4 of feed removal. When compared with the NM treatments, weight losses were significantly higher in the M treatments, regardless of water treatments. When compared with NM treatments, crop pH was significantly higher in the M treatment receiving distilled water. Crop pH was reduced to that of the NM controls by 0.5% acetic acid in the drinking water. No consistent significant changes were observed for volatile fatty acids. The number of hens positive for SE in crop and ceca after culture and the number of SE per crop and per gram of cecal contents were higher in the M treatments, when compared with the NM treatments, but there was no effect of addition of either of the acids to the drinking water. Additional research using different acid treatment regimens may provide a tool for reducing the incidence of SE in eggs and internal organs during and following molting of laying hens.

Acetic Acid↗

PubMedDate not supplied

[Effect of carbon composition of the fermented medium on the synthesis of volatile acids by the yeast Saccharomyces carlsbergensis 776].

The effect of glucose, maltose and sucrose on the synthesis of volatile oils during fermentation of model carbohydrate solutions (6, 8 and 11%) by the yeast Saccharomyces carlsbergensis 776 was studied. The composition and concentration of carbohydrates affected the build-up of volatile fatty acids during fermentation. The accumulation of biomass and volatile fraction of fatty acids reached maximum on the medium containing 11% glucose. There was a certain correlation between the biomass synthesis and accumulation of volatile fatty acids, i.e. with an increase in the biomass the content of volatile fatty acids in the medium increased. During fermentation of disaccharide solutions cell multiplication diminished and the fermentation process accelerated. Ethanol, residual sugar and acidity of fermented solutions increased with the initial concentration of carbohydrates. The pH value of the fermented must remained essentially unaltered independent of the sugar amount used.

Culture Media↗

PubMed1982

Characterization of rat cecum cellulolytic bacteria.

Cellulose-degrading bacteria previously isolated from the ceca of rats have been characterized and identified. The most commonly isolated type was rods identified as Bacteroides succinogenes. These bacteria fermented only cellulose (e.g., pebble-milled Whatman no. 1 filter paper), cellobiose, and in 43 of 47 strains, glucose, with succinic and acetic acids as the major products. The only organic growth factors found to be required by selected strains were p-aminobenzoic acid, cyanocobalamine, thiamine, and a straight-chain and a branched-chain volatile fatty acid. These vitamin requirements differ from those of rumen strains of B. succinogenes, indicating the rat strains may form a distinct subgroup within the species. The mole percent guanine plus cytosine was 45%, a value lower than those (48 to 51%) found for three rumen strains of B. succinogenes included in this study. Cellulolytic cocci were isolated less frequently than the rods and were identified as Rumminococcus flavefaciens. Most strains fermented only cellulose and cellobiose, and their major fermentation products were also succinic and acetic acids. Their required growth factors were not identified but were supplied by rumen fluid.

Animals↗

PubMed1986

Effect of source of carbohydrate and frequency of feeding on rumen parameters in dairy steers.

Four rumen-fistulated, Holstein steers (358 kg) were fed two diets at two frequencies (2 and 8 times/d) in a 4 X 4 Latin square design with 28-d periods. The two diets consisted of corn silage and a concentrate mixture in a ratio of 40:60 on a dry matter basis. The two concentrate mixtures (control and dried whole whey) contained, as a percentage: ground shelled corn, 87.85, 19.05; soybean meal, 9.4, 5.9; dicalcium phosphate, 1.7, 0; trace mineralized salt, 1.0, 1.0; vitamin A and D premix, .05, .05; and dried whole whey, 0, 74.0, respectively. Rumen fluid samples were taken at hourly intervals for 24 h and analyzed for pH, volatile fatty acids, lactate, ammonia nitrogen, and protozoal numbers. Total concentration of volatile fatty acids in the rumen were not affected by treatments. Feeding the control diet resulted in significantly higher ruminal acetate and isovalerate but lower butyrate and valerate expressed as a molar percentage. Increasing the feeding frequency from 2 to 8 times/d resulted in an increase in the molar percentage of acetate and a decrease in the concentration of lactate in ruminal fluid. Numbers of protozoa varied considerably with time after feeding and tended to be higher on the whey diet.

Ammonia↗

PubMed2001

Effect of hydraulic loading rate on acidogenesis in a membrane-coupled anaerobic VFAs fermenter.

A membrane-coupled anaerobic VFAs fermenter (MCAVF) was operated with five different hydraulic loading rates (3, 2, 1, 0.5 and 0.25 day-1) to evaluate its influence on acid phase VFAs production from coagulated raw sludge. Results show that C2 to C5 volatile fatty acids were formed as predominant compounds. At constant solids retention time (SRT) of 10 days, VFAs production ratio moderately increased over the range of hydraulic loading rate (HLR) of 3 day-1 to 2 day-1, but significantly decreased at other HLR conditions. First order hydrolysis rate constant decreased with a decrease in HLR. The relatively high degradation percentages of carbohydrate and protein were observed, ranging from 25 to 47%, 27 to 47%, respectively. However, lipid and fiber component were degraded at much lower ratio than the previous other two organic materials. On the other hand, despite some variation in the minor acids in five HLR cases, VFAs speciation appeared to be independent of HLR. The results obtained emphasize that; at least in the range investigated, the optimal HLR for VFAs production and recovery from coagulated raw sludge is in the range of 2 day-1 and 1 day-1.

Acids↗

PubMed2004

Effects of replacing dietary starch with sucrose on ruminal fermentation and nitrogen metabolism in continuous culture.

A dual-effluent continuous-culture system was used to evaluate the effects of partially replacing cornstarch with sucrose in a total mixed ration on ruminal fermentation and N metabolism. The 4 treatments were 0 (control), 2.5, 5.0, and 7.5% sucrose and, respectively, 7.5 (control), 5.0, 2.5, and 0% cornstarch in a total mixed ration containing 20% corn silage and 40% alfalfa silage. Fermenters were fed 4 times a day during four 9-d periods with sampling beginning on d 6. Replacing cornstarch with sucrose did not alter ruminal pH (5.97), total volatile fatty acids (VFA) (104.4 mmol/L), or the acetate to propionate ratio (2.16); however, branched-chain volatile fatty acids were higher for the control treatment compared with the 7.5% sucrose treatment. Five hours postfeeding, sucrose treatments significantly altered molar proportions of all volatile fatty acids, and acetate-to-propionate and glucogenic-to-lipogenic ratios. Digestibility of dry matter and N were not affected by treatment, but digestibility of total non-structural carbohydrates was increased with sucrose treatments. A quadratic effect was noted for neutral detergent fiber (NDF) digestibility as sucrose replaced starch. A higher NDF digestibility (66.1 vs. 59.9%) was observed for the 7.5% sucrose treatment compared with the other 2 sucrose treatments. Levels of ammonia N were within an acceptable range to support microbial protein synthesis and did not differ among treatments (mean=9.23 mg/dL). Sucrose inclusion in the total mixed ration did not affect bacterial N synthesis. Results indicate that (at the levels tested in this study) inclusion of sucrose in the diet when rumen-degradable protein is adequate does not affect ruminal fermentation.

Animal Feed↗

PubMed1994

The effect of condensed tannins in Lotus corniculatus on plasma metabolism of methionine, cystine and inorganic sulphate by sheep.

Fresh Lotus corniculatus containing 27 g extractable condensed tannin (CT)/kg dry matter (DM) and 8 g bound CT/kg DM was fed at hourly intervals to sheep held in metabolism cages to study the effects of CT on nutrient digestion and on metabolism of methionine, cystine and inorganic sulphate in plasma. Polyethylene glycol (PEG) was continuously infused into the rumen of half the sheep to remove the effects of CT. Principal measurements in the two groups were plasma irreversible loss (IRL) rate and interconversions of methionine, cystine and inorganic sulphate using 35S labelling. CT in Lotus corniculatus had no effects on the apparent digestion of cellulose and minerals, slightly depressed DM, organic matter and hemicellulose digestion and markedly reduced the apparent digestion of N (P < 0.01). The concentration of NH3 and molar proportions of iso-butyric acid, iso-valeric acid and n-valeric acid in rumen fluid were markedly increased by the PEG infusion (P < 0.01), whereas total volatile fatty acid concentration and molar proportions of acetic acid, propionic acid and n-butyric acid were not affected. PEG infusion temporarily increased rumen protozoa numbers. CT greatly increased the IRL of plasma cystine (13.1 v. 7.0 mumol/min; P < 0.05) and reduced IRL of plasma inorganic sulphate (36.8 v. 48.1 mumol/min; P < 0.01) but had no effect on methionine IRL. CT increased transulphuration of methionine to cystine (4.37 v. 1.24 mumol/min; P < 0.05), increased cystine entering the plasma from whole-body protein turnover plus absorption from the small intestine (9.34 v. 5.75 mumol/min; P < 0.05) and increased cystine flux to body synthetic reactions (11.89 v. 5.41 mumol/min; P < 0.05). CT had no effect on the proportion of methionine total flux transferred to sulphate (0.05 v. 0.06; P < 0.05), reduced the proportion of methionine flux transferred to body synthetic reactions (0.68 v. 0.86) and markedly reduced the proportion of cystine flux transferred to sulphate (0.09 v. 0.27; P < 0.01). It was concluded that CT in Lotus corniculatus reduced rumen protein degradation and markedly increased utilization of plasma cystine for body synthetic reactions.

Animal Feed↗

PubMed2004

Metabolic properties of Eubacterium pyruvativorans, a ruminal 'hyper-ammonia-producing' anaerobe with metabolic properties analogous to those of Clostridium kluyveri.

Eubacterium pyruvativorans I-6(T) is a non-saccharolytic, amino-acid-fermenting anaerobe from the rumen, isolated by its ability to grow on pancreatic casein hydrolysate (PCH) as sole C source. This study investigated its metabolic properties and its likely ecological niche. Additional growth was supported by pyruvate, vinyl acetate, and, to a lesser extent, lactate and crotonate, and also by a mixture of amino acids (alanine, glycine, serine and threonine) predicted to be catabolized to pyruvate. No single amino acid supported growth, and peptides were required for growth on amino acids. Alanine, followed by leucine, serine and proline, were used most extensively during growth, but only alanine and asparate were extensively modified before incorporation. Growth on PCH, but not on pyruvate, was increased by the addition of acetate, propionate and butyrate. l-Lactate was fermented incompletely, mainly to acetate, but no lactate-C was incorporated. Propionate and butyrate were utilized during growth, forming valerate and caproate, respectively. Labelling experiments suggested a metabolic pattern where two C atoms of butyrate, valerate and caproate were derived from amino acids, with the others being formed from acetate, propionate and butyrate. The metabolic strategy of E. pyruvativorans therefore resembles that of Clostridium kluyveri, which ferments ethanol only when the reaction is coupled to acetate, propionate or butyrate utilization. The fermentative niche of E. pyruvativorans appears to be to scavenge amino acids, lactate and possibly other metabolites in order to generate ATP via acetate formation, using volatile fatty acid elongation with C(2) units derived from other substrates to dispose of reducing equivalents.

Adenosine Triphosphate↗

PubMed2005

Assessment of the effects of Nurmi-type cultures and a defined probiotic preparation on a Salmonella typhimurium 29E challenge in vivo.

The effects of treatment with an undefined commercial Nurmi-type culture (NTC), cultured cecal contents, and a dual-strain probiotic, containing Enterococcus faecalis and Pediococcus pentosaceus, on Salmonella Typhimurium colonization were evaluated in a specific-pathogen-free bird model. Two sets of trials were performed, and each study was arranged as a randomized complete block design with three treatments. Treatments consisted of (i) control, (ii) commercial NTC, and (iii) cultured cecal contents in the first set of trials and (i) control, (ii) defined probiotic, and (iii) cultured cecal contents in the second set. On day 1, birds were administered 1.2 x 10(7) CFU of the appropriate treatment by oral gavage. On day 3, all birds were challenged with 1 x 10(6) CFU of Salmonella Typhimurium 29E (nalidixic acid resistant). Chicks were asphyxiated with argon gas on day 10, and ceca were aseptically removed. Salmonella Typhimurium counts (CFU per milliliter of cecal contents) were determined on brilliant green agar containing 30 mg of nalidixic acid per liter, and CFU counts were log transformed prior to analysis. Cecal pH and volatile fatty acid concentrations were also determined. Data were analyzed by one-way analysis of variance, and means were compared by Tukey's pairwise analysis. Commercial NTC and cultured cecal contents treatments resulted in a significant decrease (P < or = 0.05) in Salmonella Typhimurium 29E colonization, with the NTC offering a higher level of protection. In the second set of trials, the defined probiotic tended to reduce colonization by Salmonella Typhimurium (P = 0.07), while chicks treated with cultured cecal contents displayed a significant decrease (P = 0.03) when compared to the negative control. No significant change was observed in cecal pH or in acetate and propionate concentrations; however, a significant increase in butyrate concentrations in both the cultured cecal contents and defined probiotic treatment groups was observed when compared to the control birds. These observations suggest that defined cultures are less effective Salmonella control agents than are preparations generated from the complete cecal microflora.

Administration, Oral↗

PubMed1981

Characteristics of the rumen proteolysis of fraction I (18S) leaf protein from lucerne (Medicago sativa L).

1. The rate of proteolysis of fraction I (18S) leaf protein in the rumen of sheep of cattle was affected by diet ans the rate on fresh lucerne (medicago sativa L) was three to nine times the rate on a hay + concentrate diet. 2. Simultaneous rumen fermentations in vivo and in an artificial rumen showed that the rates of proteolysis of fraction I in vitro was approximately 30% of the rates in sheep. 3. Using 14 C uniformly-labelled fraction I protein at low concentrations, proteolysis exhibited 1st-order kinetics. Over a wide range of protein concentrations the velocity v. substrate concentration curve showed Michaelis-Menten characteristics typical of an enzyme-catalysed reaction. With rumen fluid from a hay + concentrate-fed sheep the maximum velocity was 2.6 mg protein nitrogen/1 per min and the Michaelis constant was 75 mg nitrogen/l. 4. Rapid absorption of 14C-labelled fraction I protein onto bacterial cells preceded proteolysis. 5. Sucrose-density-gradient analysis showed initial incorporation of 14C from protein into rumen bacteria followed by partial transfer to rumen protozoa. 6. No peptides were detected during proteolysis showing that the rate-limiting step occurred during the initial stages of proteolysis. Only small amounts of free amino acids were released except for leucine, isoleucine, valine and ornithine, which showed significantly increased levels. 7. Volatile fatty acids were the main 14C-labelled end products and were rapidly produced in descending concentrations: acetate greater than propionate greater than 3-methyl + 2-methyl butyrate greater than butyrate greater than isobutyrate greater than valerate.

Amino Acids↗

PubMed1985

Digestion and absorption of lipids and bile acids in sheep fed stearic acid, oleic acid, or tristearin.

Sheep were fed diets containing 7.5% added stearic acid, oleic acid, or tristearin for 21 days. In addition, 50 microCi/kg cerium-141 was included for the last 10 days on experimental diets as an unabsorbed reference substance. In the rumen dietary triglycerides were approximately 50% hydrolyzed, and hydrogenation resulted in saturation of the free fatty acid fraction. Some net synthesis of phospholipids, presumably microbial phospholipids, occurred in the rumen. In the intestine immediately distal to the pylorus, extensive secretion of bile acids, cholesterol, phospholipids, triglycerides, free fatty acids, and lipase occurred. This resulted in doubling of fatty acid fluxes through the duodenum. These endogenous secretions were reabsorbed rapidly however, with the major site of lipid and bile acid absorption in the region .6 to 4 m distal to the pylorus. Additional but less absorption occurred in the more distal segments of the small intestine. Overall absorption of stearic acid, oleic acid, and tristearin supplements was in the range 60 to 70%, and no differences were apparent between fats. Unsaturated fatty acids were over 90% absorbed as compared with 55 to 65% for saturated fatty acids. No significant effect of any of the supplements was observed on ruminal total volatile fatty acids, ratios of volatile fatty acids, or on overall cellulose or caloric digestion.

Abomasum↗

PubMed1977

Gluconeogenesis in cattle: significance and methodology.

Gluconeogenesis is a continual process that is of great importance in ruminants because almost all dietary carbohydrates are fermented to volatile fatty acids in the rumen. In turn, propionate is the only major volatile fatty acid that contributes to gluconeogenesis. Many different techniques and analytical procedures are involved in studying ruminant gluconeogenesis. Glucose kinetics can be examined by single-injection or continuous-infusion isotope dilution techniques with a variety of glucose labels. Correcting for recycling of label is an important consideration. Absorption of glucose from the gut can be measured by combining arterial-venous differences and flow rates of portal blood or can be estimated by determining the amount of glucose plus alpha-glucose polymers passing into the small intestine. Production of propionate in the ruminoreticulum can be measured by isotope dilution techniques. Quantitating the conversion of propionate to glucose requires the use of [carbon-14]propionate with careful corrections for propionate carbon entering the citric acid cycle before incorporation into glucose; The same fundamental techniques used with propionate are required to quantitate the contributions of amino acids and other precursors to glucose. In vitro studies of gluconeogenic enzymes, and cellular, tissue, or organ preparations provide valuable insights into the gluconeogenic processes and controls but must be validated by in vivo experiments. Progress has been considerable in understanding some aspects of ruminant gluconeogenesis, but many more studies will be required to obtain a complete understanding.

Amino Acids↗

PubMed1986

[Influence of caecotrophy (coprophagia) on the production, absorption and utilization of organic acids in the rabbit].

The influence of caecotrophy on organic acid production and behaviour was studied for 4 days in rabbits with and without a collar preventing caecotrophy. Volatile fatty acids (VFA) and lactate were measured in the digestive material and the corresponding venous blood. Blood was removed from the gastric, intestinal, caecocolonic, portal and hepatic veins and the inferior vena cava of anaesthetized rabbits. Arterial blood was also collected. A comparison of the data obtained from rabbits with and without a collar showed significant differences. When caecotrophy was prevented, lactic fermentation in the stomach ceased and the lactate level dropped in venous and arterial blood. Meanwhile, VFA production in the foregut (stomach and intestine) stopped, whereas it augmented in the hindgut; VFA enrichment of the caecocolonic and portal blood was greater when the rabbits were subjected to a stercoral fast. The liver removed about 15% of the lactate reaching it, while acetate, propionate and butyrate uptakes were 21, 59 and 76%, respectively, in rabbits with caecotrophy. The corresponding values for those without caecotrophy were: 20% lactate, 43% acetate, 70% propionate and 84% butyrate. The plasma venous-arterial difference in acetate was negative in the peripheral blood: uptake was about 16% for the controls and 27% for rabbits without caecotrophy; the other VFA were not involved. The variations of the levels of VFA in the arterial blood were not significant; only lactate concentration diminished by about 30%. Preventing caecotrophy augmented digestive production, and the absorption of VFA in the rabbit hindgut and their metabolism in the liver and extra-hepatic tissues also increased.

Animals↗

PubMed1997

The effect of calcium gluconate and other calcium supplements as a dietary calcium source on magnesium absorption in rats.

The effects of commercially available calcium supplements (calcium carbonate, calcium gluconate, oyster shell preparation and bovine bone preparation) and gluconic acid on the absorption of calcium and magnesium were evaluated for 30 days in male Wistar rats. There were no differences in the apparent absorption ratio of calcium among rats fed each calcium supplement; however, the rats fed the calcium gluconate diet had a higher apparent absorption ratio of magnesium than the rats fed the other calcium supplements. Dietary gluconic acid also more markedly stimulated magnesium absorption than the calcium carbonate diet, and the bone (femur and tibia) magnesium contents of rats fed the gluconic acid diet were significantly higher than those of the rats fed the calcium carbonate diet. Furthermore, the weight of cecal tissue and the concentrations of acetic acid and butyric acid in cecal digesta of rats fed the calcium gluconate diet or the gluconic acid diet were significantly increased. We speculate that the stimulation of magnesium absorption in rats fed the calcium gluconate diet is a result of the gluconic acid component and the effect of gluconic acid on magnesium absorption probably results from cecal hypertrophy, magnesium solubility in the large intestine and the effects of volatile fatty acids on magnesium absorption.

Absorption↗

PubMed1975

[Effect of DL-lactic acid on voluntary food intake in sheep (author's transl)].

Previous experiments indicate that changes in duodenal fluid concentration of DL-lactic and volatile fatty acids (VFA) influence flow rate of ingesta and may also be a regulating factor of food intake in ruminants. The present experiment was designed to determine the sensitivity of the duodenum to DL-lactic acid and VFA in relation to diets of hay, dried grass or concentrates. On a diet of hay, administration of small amounts of either DL-lactic acid or VFA into the duodenum had no effect. On a diet of dried grass or concentrates the same amount of VFA had no effect but that of DL-lactic acid (12 mM/h) halved the dry matter intake. In animals on a diet of hay and after administration of 40 g of propionate into the rumen, duodenal perfusion of the same quantity of DL-lactic acid produced a similar reduction of food intake. It was concluded that duodenal DL-lactic acid acts as a regulator of food intake possibly via the propionate metabolism pathway.

Animal Feed↗

PubMed2004

Influence of animal origin and lineage on survival of Escherichia coli O157:H7 strains in strong and weak acid challenges.

Twenty-five strains of Escherichia coli O157:H7 isolated from humans, cattle, and pigs were maintained in HCl (pH 2.5) and in a volatile fatty acid (VFA) mixture (pH 4.0) for up to 6 h at 37 degrees C to assess their ability to survive in acidic conditions that simulate those of the stomach and ileum, respectively. In HCl, the average group survival of bovine strains was significantly higher than that of porcine and human strains, whereas in VFAs, porcine strains were significantly more resistant than bovine and human strains. Bovine strains exhibited significantly higher average survival in HCl than in VFAs. The average survival of strains classified as octamer-based genome scanning (OBGS) lineage II was significantly superior to that of strains classified as OBGS lineage I in HCl. The group of lineage I strains was more resistant in VFAs compared with lineage II, but only after 6 h of challenge. The possible involvement of urease in acid resistance of E. coli O157:H7 was also examined. Although the strains possessed the ureC gene, as shown by PCR, this gene did not appear to contribute to acid resistance under the conditions tested. The data indicate that there is a relationship between acid resistance and source or lineage of O157:H7 strains.

Animals↗

PubMed1964

EFFECT OF ABSENCE OF CILIATE PROTOZOA FROM THE RUMEN ON MICROBIAL ACTIVITY AND GROWTH OF LAMBS.

A survey of the components of the rumen ciliate population in a series of adult sheep, raised in the Faculty of Agriculture, University of Alexandria, has shown that a mixture of Entodinium, Isotricha, Ophryoscolex, Diplodinium, and Polyplastron species was found in the rumen contents of Egyptian sheep; no Epidinium and a negligible number of Dasytricha ruminantium were also observed. The microbial population, reducing sugars, ammonia, volatile fatty acids (VFA) production, and growth rate of 14 lambs inoculated with whole rumen contents from a mature sheep were compared over a 6-month period with those of 13 lambs maintained under the same conditions, except that they were strictly isolated from other ruminants. Certain large oval organisms and large numbers of flagellates and Oscillospira were frequently observed in the rumen contents of the isolated lambs. The reducing sugars, ammonia, and VFA levels, measured before and at intervals after feeding, in the inoculated lambs showed a pronounced rise above the values found in the ciliate-free animals. The propionic acid-acetic acid ratio in the rumen contents of the faunated lambs was considerably higher than in the nonfaunated controls. The inoculated lambs grew faster than the isolated lambs. Differences in weight gain which ranged from 15 to 17% were statistically significant. The inoculated animals impressed the observers by their good appearance which was superior to that of the ciliate-free lambs. It was, therefore, concluded that the rumen ciliate protozoa are essential for the metabolism and growth of young lambs.

Acetic Acid↗

PubMedDate not supplied

Biological control of Salmonella typhimurium in young chickens.

The effect of dietary lactose and anaerobic cultures of cecal microflora of mature chickens on the colonization of young broiler chickens by Salmonella typhimurium was evaluated. Newly hatched chicks were given either no treatment (controls), anaerobic cecal cultures, lactose (2.5%) in the drinking water, or both anaerobic cultures and lactose. Chicks were challenged per os at 3 days of age with either 10(6) or 10(8) S. typhimurium resistant to nalidixic acid and novobiocin. On day 10, the cecal contents of the chicks were examined for S. typhimurium, pH, short-chained volatile fatty acids (VFAs), undissociated VFAs, and lactic acid. Chicks given either lactose alone or cecal anaerobes alone had significantly (P less than 0.05) fewer S. typhimurium recovered from their ceca than the controls. Chicks given the combination of dietary lactose and cecal anaerobes had significantly fewer S. typhimurium recovered from their ceca than the chicks given dietary lactose or cecal anaerobes alone. Chicks given lactose had significant (P less than 0.05) increases in the lactic acid concentration of their cecal contents. Increased lactic acid concentrations were directly correlated to decreased cecal pH values and caused a reduction in the total concentration of VFAs but a significant (P less than 0.05) increase in the undissociated form of some VFAs.

Animals↗