Effect of benzoic acid on growth performance, nutrient digestibility, nitrogen balance, gastrointestinal microflora and parameters of microbial metabolism in piglets

Mixed organic acids improve nutrients digestibility, volatile fatty acids composition and intestinal microbiota in growing-finishing pigs fed high-fiber diet

Objective

The objective of this study was to investigate effects of mixed organic acids (MOA) on nutrient digestibility, volatile fatty acids composition and intestinal microbiota in growing-finishing pigs fed high wheat bran diet.

Methods

Six crossbred barrows (Duroc×Landrace×Yorkshire), with an average body weight 78.8±4.21 kg, fitted with T-cannulas at the distal ileum, were allotted to a double 3×3 Latin square design with 3 periods and 3 diets. Each period consisted of a 5-d adjustment period followed by a 2-d total collection of feces and then a 2-d collection of ileal digesta. The dietary treatments included a corn-soybean-wheat bran basal diet (CTR), mixed organic acid 1 diet (MOA1; CTR+3,000 mg/kg OA1), mixed organic acid 2 diet (MOA2; CTR+2,000 mg/kg OA2).

Results

Pigs fed MOA (MOA1 or MOA2) showed improved (p<0.05) apparent total tract digestibility (ATTD) of gross energy, dry matter and organic matter, and pigs fed MOA2 had increased (p<0.05) ATTD of neutral detergent fiber compared to CTR. Dietary MOA supplementation decreased (p<0.05) pH value, and improved (p<0.01) concentrations of lactic acid and total volatile fatty acids (TVFA) in ileum compared to CTR. Pigs fed MOA showed higher (p<0.05) concentration of acetic acid, and lower (p<0.05) content of formic acid in feces compared to CTR. Pigs fed MOA1 had increased (p<0.05) concentration of TVFA and butyric acid in feces. Pigs fed MOA1 showed higher concentration of Lactobacillus and lower concentration of Escherichia in feces compared to CTR.

Conclusion

Dietary supplementation of MOA 1 or 2 could improve nutrients digestibility, TVFA concentration and intestinal flora in growing-finishing pigs fed high fiber diet.

Benzoic acid in nursery diets increases the performance from weaning to finishing by reducing diarrhoea and improving the intestinal morphology of piglets inoculated with Escherichia coli K88. J Anim Physiol Anim Nutr (Berl) 2018;102:1675-1685. [PMID: 30094927 DOI: 10.1111/jpn.12977]

A total of 224 weaned pigs (DanBred sows x PIC 337 sires) with an average body weight (BW) of 6.37 ± 0.34 kg (21 days of age) were used to evaluate how different levels of benzoic acid fed to weaning pigs orally inoculated with Escherichia coli (K88⁺ ) affected the nursing and grow-finishing performance, the physicochemical properties of the intestine, the volatile fatty acid concentration in the caecum and the incidence of diarrhoea. Pigs were randomly allocated in an experimental design of randomized blocks in a 4 × 2 factorial design, and they were administered four levels of benzoic acid (0.00%, 0.25%, 0.50% and 0.75%) and inoculated (or not) in two consecutive days with 1 ml solution containing 10⁶ CFU/ml of E. coli (K88⁺ ). Seven replicates (pens) per treatment were used, and four animals were kept per pen. Supplementation with 0.75% benzoic acid promoted better performance (p < 0.05) in the nursery phase as well as in the subsequent phases until slaughter, and it decreased the incidence of diarrhoea in piglets (p < 0.05). In the piglets fed the benzoic acid diet, the villus height in the jejunum and ileum was greater until 42 days of life (p < 0.05), the crypt depth was decreased in the caecum (p < 0.05), and the butyric acid concentration was increased in the caecal content tendencially (p = 0.0708). In conclusion, supplementation with 0.75% benzoic acid has a positive effect on piglets by reducing diarrhoea, improving intestinal health and promoting the performance from weaning to finishing. Thus, benzoic acid can be considered a potential alternative that can replace growth-promoting antibiotics.

Alpha-Ketoglutarate in Low-Protein Diets for Growing Pigs: Effects on Cecal Microbial Communities and Parameters of Microbial Metabolism

Alpha-ketoglutarate (AKG), a critical molecule in the tricarboxylic acid cycle, is beneficial to intestinal functions. However, its influence on intestinal microbiota and metabolism is not fully understood. We investigated the effects of a low-protein (LP) diet supplemented with AKG on cecal microbial communities and the parameters of microbial metabolism in growing pigs. Twenty-seven young pigs (Large White × Landrace) with an average initial body weight of 11.96 ± 0.18 kg were randomly allotted into three groups (n = 9): a normal protein (NP) diet containing 20% crude protein (CP); LP diet formulated with 17% CP (LP diet); or LP diet supplemented with 10 g kg^-1 of AKG (ALP diet). After a 35-day trial period, the digesta of the cecum were collected to analyze the concentrations of ammonia and short-chain fatty acids (SCFAs). We also performed a microbial analysis. Although no significant differences were found in performance among the diet groups, pigs fed the ALP diet had greater average daily gain (ADG) when compared with those in the LP group. Experimental diet did not affect cecal bacterial richness or diversity, as determined by Chao1 and ACE species richness measures and Shannon and Simpson indices, respectively. The predominant phyla Firmicutes, Bacteroidetes, and Proteobacteria increased in relative abundances in the cecum of pigs fed ALP diet. At the genus level, compared to the LP diet, the ALP diet significantly increased the abundances of Lachnospiraceae UCG-005, Lachnospiraceae NK4A136 group, Phascolarctobacterium and Parabacteroides, while decreased Vibrio and Maritalea. Pigs fed the ALP diet increased Oribacterium and Lachnoclostridium when compared with the NP diet. Non-metric multidimensional scaling analysis revealed that the distribution of microbiota at each group was distinctly clustered separately along principal coordinate. In addition, quantitative PCR revealed that the ALP diet was also associated with increases in the amounts of Bacteroides, Bifidobacterium, and Lactobacillus, but a decrease in the level of Escherichia coli. Compared with the NP diet, the ALP diet enhanced the concentrations of valerate and propionate. This ALP diet also increased the concentrations of valerate and isobutyrate when compared with the LP diet. Moreover, the ALP diet was linked with a significant decline in the concentration of ammonia in the cecum. These results indicate that a LP diet supplemented with AKG can alter the balance in microbial communities, increasing the population of SCFA-producing bacteria and the amounts of Bacteroides and Bifidobacterium, while reducing the counts of Escherichia coli and the amount of ammonia in the cecum.

Growth performance of nursery and grower-finisher pigs fed diets supplemented with benzoic acid

Two experiments were conducted to investigate the efficacy of benzoic acid on the growth performance of nursery and grower-finisher pigs. A randomized complete block design was used in both experiments with the initial body weight as the blocking factor. There were 3 treatments corresponding to 3 dietary levels of benzoic acid: 0, 0.3%, and 0.5%. In experiment 1, a total of 144 PIC L1050 barrows (initial body weight 7.1 ± 0.6 kg) were used with each treatment replicated 8 times. In experiment 2, a total of 288 PIC L1050 barrows (initial body weight 36.1 ± 3.6 kg) were used with each treatment replicated 16 times. There were 6 barrows in each replicate pen for both experiments. Experiments 1 and 2 lasted 28 and 70 days, respectively. In experiment 1, average daily gain (ADG) of all growth phases increased linearly (P < 0.05) with increasing supplementation of benzoic acid, which led to a linear improvement in average body weight on d 28 (P < 0.05). There was also an improvement in feed conversion ratio (FCR) of d 0 to 14 (linear effect: P < 0.05) and in average daily feed intake (ADFI) of d 14 to 28 and d 0 to 28 (linear effect: P < 0.01). In experiment 2, ADG during d 0 to 35 and d 35 to 70 and average body weight on d 35 improved linearly (P < 0.05) with increasing supplementation of benzoic acid. Average daily gain of d 0 to 70 and average body weight on d 70 increased significantly in a both linear and quadratic manner. There was a linear improvement in FCR in all growth phases (P < 0.05). In conclusion, the dietary inclusion of benzoic acid at the supplementation levels of 0.3% and 0.5% significantly improved the growth performance of nursery and grower-finisher pigs in the current study; the nursery pigs responded to the dietary supplementation of benzoic acid up to 0.5% linearly while the grower-finisher pigs achieved the optimal ADG at the calculated supplementation level of 0.36%.

The effects of amoxicillin treatment of newborn piglets on the prevalence of hernias and abscesses, growth and ampicillin resistance of intestinal coliform bacteria in weaned pigs

This study investigated the effects of a single amoxicillin treatment of newborn piglets on the prevalence of hernias and abscesses until the age of nine weeks. We also studied whether the treatment was associated with growth and mortality, the need for treatment of other diseases, the proportions of ampicillin resistant coliforms and antimicrobial resistance patterns of intestinal Escherichia coli (E. coli). A total of 7156 piglets, from approximately 480 litters, were divided into two treatment groups: ANT (N = 3661) and CON (N = 3495), where piglets were treated with or without a single intramuscular injection of 75 mg amoxicillin one day after birth, respectively. The umbilical and inguinal areas of weaned pigs were palpated at four and nine weeks of age. At the same time, altogether 124 pigs with hernias or abscesses and 820 non-defective pigs from three pens per batch were weighed individually. Mortality and the need to treat piglets for other diseases were recorded. Piglet faecal samples were collected from three areas of the floors of each pen at four weeks of age. The prevalence of umbilical hernias or abscesses did not differ between the groups at four weeks of age, but it was higher in the CON group than in the ANT group at nine weeks of age (2.3% vs. 0.7%, P < 0.05). Numbers of inguinal hernias and abscesses did not differ between the groups at four or nine weeks of age. The ANT group, when it compared with the CON group, increased the weight gain between four and nine weeks of age (LS means ± SE; 497.5 g/d ± 5.0 vs. 475.3 g/d ± 4.9, P < 0.01), and decreased piglet mortality (19.5% ± 1.0 vs. 6.9% ± 1.0, P < 0.05) and the need to treat the piglets for leg problems (3.4% ± 0.3 vs. 1.9% ± 0.3%, P < 0.01) but not for other diseases by the age of four weeks. The proportion of ampicillin resistant intestinal coliform bacteria and the resistance patterns of the E. coli isolates were not different between the ANT and CON groups. In conclusion, our results showed that the amoxicillin treatment of new-born piglets produced statistically significant effect in some of the parameters studied. However, as these effects were only minor, we did not find grounds to recommend preventive antibiotic treatment. Further, continuous antimicrobial treatment of newborn piglets could negatively influence the development of the normal microbiota of the piglet and promote selection of antimicrobial resistance genes in herds. Therefore we suggest rejection of the use of routine administration of antimicrobial agents at birth.

Dietary effect of apple cider vinegar and propionic acid on immune related transcriptional responses and growth performance in white shrimp, Litopenaeus vannamei

This experiment was conducted to study the effect of various levels of ACV^® and Propionic acid (PA) on expression of immune related genes and growth performance in white shrimp (Litopenaeus vannamei). Three hundred and seventy-five shrimps with an average initial weight of 10.2 ± 0.04 g were collected and acclimatized for two weeks. Five experimental diets including control diet, 0.5% PA diet and 1%, 2% and 4% ACV^® diets were applied to feed the shrimps. They were fed 4 times a day with 2.5% of body weight. After 60 days of culture, shrimps fed with ACV^® and PA diets showed no significant difference in growth performance. Expression of prophenoloxidase (proPo), lysozyme (Lys), penaeidin-3a (Pen-3a) and Crustin (Cru) genes were determined from hepatopancreas, using the real-time PCR after 15, 30 and 60 days. Expression of Lys and proPo genes was significantly up regulated in shrimps fed with ACV^® and PA diets compared to the control group after 30 and 60 days of treatment. After 15 days, Pen-3a gene expression was significantly higher in PA group compared to the control group. Also, shrimps fed with 1% and 4% ACV^® and PA diets showed significantly increased expression of Pen-3a after 30 days. In contrast, expression of Cru was significantly down regulated in response to ACV^® diets, but, Cru expression in treated shrimps with PA diet was greater than the control group after 30 and 60 days. Overall, the results provided evidence that ACV^® could be used as a natural immunostimulant for shrimps in order to adjust and enhance expression of the immune related genes.

Benzoic acid beneficially affects growth performance of weaned pigs which was associated with changes in gut bacterial populations, morphology indices and growth factor gene expression

This study was conducted to investigate the effects of benzoic acid (BA) on growth performance, intestinal development and intestinal barrier function in weaned pigs. Ninety weaned pigs were randomly assigned to one of three treatments: a basal diet (CON), the basal diet supplemented with 2000 mg/kg benzoic acid (BA1) and 5000 mg/kg benzoic acid (BA2). At the end of days 14 and 42, six pigs per treatment were randomly selected to collect plasma and intestinal samples. Results showed that BA supplementation not only improved final body weight, daily growth and feed conversion ratio from days 15 to 42 and days 1 to 42, but also decreased the activity of plasma diamine oxidase (day 42) and the pH values of jejunal contents (day 14) (p < 0.05). Ileal Bacillus populations (day 14) were increased by BA, while Escherichia coli counts in the ileum and caecum (day 42) were decreased (p < 0.05). Higher Lactobacillus counts occurred in the ileum (day 14, 42) of BA1-fed piglets as compared to CON and BA2-fed piglets (p < 0.05). In addition, BA supplementation increased the ratio of villus height to crypt depth (day 14, 42) and decreased the crypt depth (day 14) (p < 0.05). Growth-stimulating factors (insulin-like growth factor-1, day 42; insulin-like growth factor-1 receptor, day 14, 42) and tight junction protein (occludin, day 14, 42; zonula occludens-1, day 42)-related gene mRNA levels were upregulated in the jejunum of piglets fed BA diets (p < 0.05). In conclusion, this study provides the first evidence that BA has beneficial effects on intestinal development and intestinal barrier function of weaned pigs, which can partly explain why growth performance of pigs was improved by dietary BA supplementation.

Effects of benzoic acid (VevoVitall®) on the performance and jejunal digestive physiology in young pigs

Background

As a organic acid, benzoic acid has become one of the most important alternatives for antibiotics, and its beneficial effect on performance in animals has been proven for a decade. However, knowledge of the effects of benzoic acid on jejunal digestive physiology, especially the antioxidant capacity and mucosal glucagon-like peptide 2 (GLP-2) concentrations is lacking.

Methods

A total of 20 barrows [Duroc × (Yorkshire × Landrace)] with an average body weight (BW) of 18.75 ± 0.2 kg were used in a 14-d trial to determine the potential mechanisms of benzoic acid supplementation on the performance, nutrient digestibility and jejunal digestive physiology in young pigs. All pigs were randomly allotted to 1 of 2 diets supplemented with 0 or 5000 mg/kg benzoic acid.

Results

Relative to the control, benzoic acid supplementation increased the average daily feed intake (ADFI), and average daily gain (ADG) in young pigs (P < 0.05), improved the apparent total tract digestibility of dry matter (DM), crude protein (CP), ether extract (EE), gross energy (GE) and crude ash (P < 0.05), and enhanced the activities of trypsin, lipase and amylase in the jejunum (P < 0.05). Similarly, relative to the control, supplementing benzoic acid in the diet resulted in a trend to reduce the pH values of the digesta (P = 0.06), decreased crypt depth and increased the villus height to crypt depth ratio (P < 0.05) in the jejunum of pigs. Finally, benzoic acid supplementation increased the mRNA expression and concentration of glucagon-like peptide 2 and the activities of glutathione peroxidase and superoxide dismutase in the jejunal mucosa of young pigs (P < 0.05).

Conclusions

In conclusion, supplementation with 5000 mg/kg benzoic acid improved the performance of young pigs through promoting nutrient digestion, improving jejunal antioxidant capacity, and maintaining the jejunal morphology in young pigs.

Effects of benzoic Acid and thymol on growth performance and gut characteristics of weaned piglets

A total of 144 weaned crossed pigs were used in a 42-d trial to explore the effects of different concentrations/combinations of benzoic acid and thymol on growth performance and gut characteristics in weaned pigs. Pigs were randomly allotted to 4 dietary treatments: i) control (C), basal diet, ii) C+1,000 mg/kg benzoic acid+100 mg/kg thymol (BT1), iii) C+1,000 mg/kg benzoic acid+200 mg/kg thymol (BT2) and, iv) C+2,000 mg/kg benzoic acid+100 mg/kg thymol (BT3). Relative to the control, pigs fed diet BT3 had lower diarrhoea score during the overall period (p<0.10) and improved feed to gain ratio between days 1 to 14 (p<0.05), which was accompanied by improved apparent total tract digestibility of ether extract, Ca and crude ash (p<0.05), and larger lipase, lactase and sucrose activities in the jejunum (p<0.05) at d 14 and d 42. Similarly, relative to the control, pigs fed diet BT3 had higher counts for Lactobacillus spp in digesta of ileum at d 14 (p<0.05), and pigs fed diets BT1, BT2, or BT3 also had higher counts of Bacillus spp in digesta of caecum at d 14 (p<0.05), and lower concentration of ammonia nitrogen in digesta of caecum at d 14 and d 42 (p<0.05). Finally, pigs fed diet BT3 had higher concentration of butyric acid in digesta of caecum at d 42 (p<0.05), and a larger villus height:crypt depth ratio in jejunum and ileum at d 14 (p<0.05) than pigs fed the control diet. In conclusion, piglets fed diet supplementation with different concentrations/combinations of benzoic acid and thymol could improve feed efficiency and diarrhoea, and improve gut microfloral composition. The combination of 2,000 mg/kg benzoic acid+100 mg/kg thymol produced better effects than other treatments in most measurements.

Effects of Acidifying Pig Diets on Emissions of Ammonia, Methane, and Sulfur from Slurry during Storage

Ammonia (NH) volatilization from intensive livestock production is a threat to natural ecosystems. This study investigated pig diet manipulation by 1% (w/w) benzoic acid (BA) amendment and lowering of dietary electrolyte balance through substituting 1.4% (w/w) CaCO with 2.0% (w/w) CaCl. Urine and feces were collected separately from 24 pigs fed one of four diets (Control, +BA, +CaCl, +BA+CaCl) in metabolic cages and mixed as slurry. During 103 d of storage, all acidifying diets consistently reduced pH in the slurry by 0.4 to 0.6 units. There was a strong relationship between slurry pH and NH emissions, which were considerably reduced by the three acidifying diets. The +BA diet decreased NH emission by 28%, the +CaCl diet by 37%, and the combined +BA and +CaCl diet by 40%. Acidifying diets had no effect on S cycling or emission of volatile S compounds under the prevailing conditions of restricted S feeding. Methane (CH) emissions were increased by 73% in diets with CaCl. An initial delay in CH emissions was investigated in a separate experiment with manipulation of pH (5.4, 6.7, or 8.8) and inoculation with adapted pig slurry (0, 4, 11, or 19%), which showed that methanogenic potential, rather than inhibitory effects of the chemical environment, caused the delay. In conclusion, NH emissions from slurry could be reduced by addition of BA to pig diets or by controlling the dietary electrolyte balance, but there was no additive effect of combining the two strategies. However, CH emissions from slurry may increase with acidifying diets.

Modification of digesta pH and intestinal morphology with the use of benzoic acid or phytobiotics and the effects on broiler chicken growth performance and energy and nutrient utilization

Two experiments, each consisting of 2 trials, were conducted to investigate the effect of feeding benzoic acid (BA) and turmeric meal (TM) individually or in combination (Exp. 1) or garlic meal (GM) and TM individually or in combination (Exp. 2) on growth performance, digesta pH, gut morphology, and nutrient utilization in broiler chickens. Diets consisted of a nutrient-adequate control diet and the control diet with added BA (2 g/kg), TM (10 g/kg), BA (1 g/kg) plus TM (5 g/kg), and BA (2 g/kg) plus TM (10 g/kg) in Exp. 1. In Exp. 2, in addition to the same control diet as Exp. 1, the control diet with added GM (10 g/kg), TM (10 g/kg), GM plus TM at 5 g/kg each, and GM plus TM at 10 g/kg each were used. Each treatment had 6 replicate floor pens with 10 chickens per replicate. On d 14, 5 broiler chickens from each floor pen were transferred to metabolism cages and continued on their respective diets. Body weight and feed intake data were collected on d 0 and 21, excreta were collected from chickens in metabolism cages on d 19 and 20, and ileal digesta were collected on d 21. Digesta pH was measured at the crop, proventriculus, jejunum, and cecum. Jejunum sections were collected from chickens in Exp. 1 to study gut morphology. In Exp. 1, only the combination of BA and TM tended (P < 0.10) to improve weight gain but there were no effects on G:F. The combination of BA and TM at both inclusion rates decreased (P < 0.05) digesta pH in the crop, jenunum, and ceca. There were no treatment effects on ileal DM or total tract DM retention, but supplementation of BA or TM alone or in combination increased (P < 0.01) apparent ME (AME) and nitrogen-corrected AME (AMEn) relative to the control diet. In Exp. 2, TM alone or combined with GM improved (P < 0.05) weight gain and G:F compared to the control. Supplementation of TM alone or in combination with GM at the rate of 10 g/kg each reduced (P < 0.05) digesta pH in the crop, proventriculus, and ceca but had no effect at the jejunum. The combination of GM and TM improved (P < 0.01) ileal DE, AME, and AMEn. In conclusion, BA, TM, and GM individually or in combination with wheat-soybean meal based diets adequate in nutrients and energy selectively improved growth performance, modified digesta pH and intestinal growth, and increased the efficiency of dietary energy use.

Dietary Supplementation of Benzoic Acid and Essential Oil Compounds Affects Buffering Capacity of the Feeds, Performance of Turkey Poults and Their Antioxidant Status, pH in the Digestive Tract, Intestinal Microbiota and Morphology

Three trials were conducted to evaluate the effect of supplementation of a basal diet with benzoic acid or thymol or a mixture of essential oil blends (MEO) or a combination of benzoic acid with MEO (BMEO) on growth performance of turkey poults. Control groups were fed a basal diet. In trial 1, benzoic acid was supplied at levels of 300 and 1,000 mg/kg. In trial 2, thymol or the MEO were supplied at levels of 30 mg/kg. In trial 3, the combination of benzoic acid with MEO was evaluated. Benzoic acid, MEO and BMEO improved performance, increased lactic acid bacteria populations and decreased coliform bacteria in the caeca. Thymol, MEO and BMEO improved antioxidant status of turkeys. Benzoic acid and BMEO reduced the buffering capacity compared to control feed and the pH values of the caecal content. Benzoic acid and EOs may be suggested as an effective alternative to AGP in turkeys.

Vibrational spectral investigations and density functional theory study of 4-Formylbenzoic acid

An accurate assignment of the vibrational spectra of 4-Formylbenzoic acid in solid state was carried out. For this purpose density functional calculations (DFT) were performed to clarify wavenumber assignments of the experimentally observed bands for the first time. A scaling of the wavenumbers was carried out to improve the calculated values. Good reproduction of the experimental wavenumbers is obtained and the % error is very small in the majority of cases. The NBO analysis was carried out, and it reveals hyper conjugative interaction, ICT and stabilization of molecules.

Effects of a blend of essential oil compounds and benzoic acid on performance of broiler chickens as revealed by a meta-analysis of 4 growth trials in various locations

A series of growth trials with broiler chicks was conducted in various geographical locations to evaluate the efficacy of a novel eubiotic feed additive (EFA) at various dietary inclusion levels on performance of growing chicks. The EFA product consisted of a blend of essential oil compounds (thymol, eugenol, piperine) with benzoic acid, all belonging to the group of flavoring substances. Although variable in responses, the overall results indicated that 300 mg/kg of this EFA represented an optimum supplementation dose for generation of beneficial performance effects in broilers. A meta-analysis with all data from the 300 mg/kg EFA-supplemented treatments in comparison with the non-supplemented controls revealed that the eubiotic product significantly improved BW on d 21 (+2.0%; P = 0.0021) and on d 42 (+1.4%; P = 0.0151). Furthermore, the birds on the EFA 300 mg/kg treatment expressed a higher average daily gain in the starter phase (d 1-21; +2.1%; P = 0.0023) and over the entire experimental period (d 1-42; +1.5%; P = 0.0154). Feed conversion ratio was more favorable with dietary EFA supplementation (-0.6%; P = 0.0414), when compared with the control birds. Mortality was considered normal and was not affected by the dietary treatment (control = 3.09%; EFA 300 mg/kg = 3.26%). In conclusion, 300 mg/kg of this new eubiotic product demonstrated to effectively improve performance of broiler chicks under various husbandry conditions.

Phenotypic changes in spores and vegetative cells of Bacillus anthracis associated with BenK

A transposon insertional mutagenesis spore library of the pathogen Bacillus anthracis was screened to identify mutants altered in germination kinetics. One mutant exhibited an accelerated rate of germination in association with disruption of benK. This gene encodes a putative protein with high homology to membrane transporters that facilitate benzoate transport. We hypothesized that BenK may not be only spore associated, but also have a vegetative cell role. A reporter strain with a translational fusion of benK to green fluorescent protein demonstrated that full-length BenK was present in vegetative cells and that a BenK degradation product was present in spores by detecting the reporter using fluorescence and Western blot analysis. A minimum inhibitory concentration assay indicated that vegetative cells of a benK::Kan mutant were more susceptible to the antimicrobial effects of Na-benzoate. The mutant spores germinated to a greater extent within 1 h than the wild type in an in vitro fluorescence assay. The disruption of benK also resulted in spores that were less readily phagocytosed in a macrophage assay. Despite these altered in vitro phenotypes, no apparent effect of the BenK protein on virulence in the intranasal mouse model or the guinea pig competitive assay was observed. This work shows that, although the BenK protein does not impact fitness or virulence in an infection model, it is involved in other aspects of both the spore and vegetative forms of the organism.

Impact of bioactive substances on the gastrointestinal tract and performance of weaned piglets: a review

The EU ban on in-feed antibiotics has stimulated research on weaning diets as a way of reducing post-weaning gut disorders and growth check in pigs. Many bioactive components have been investigated but only few have shown to be effective. Amongst these, organic acids (OA) have been shown to exert a bactericidal action mediated by non-dissociated OA, by lowering gastric pH, increasing gut and pancreas enzyme secretion and improving gut wall morphology. It has been postulated that they may also enhance non-specific immune responses and improve disease resistance. In contrast, relatively little attention has been paid to the impact of OA on the stomach but recent data show they can differently affect gastric histology, acid secretion and gastric emptying. Butyrate and precursors of butyric acid have received special attention and although promising results have been obtained, their effects are dependent upon the dose, treatment duration, initial age of piglets, gastrointestinal site and other factors. The amino acids (AA) like glutamine, tryptophan and arginine are supportive in improving digestion, absorption and retention of nutrients by affecting tissue anabolism, stress and (or) immunity. Glutamine, cysteine and threonine are important for maintaining mucin and permeability of intestinal barrier function. Spray-dried plasma (SDP) positively affects gut morphology, inflammation and reduces acquired specific immune responses via specific and a-specific influences of immunoglobulins and other bioactive components. Effects are more pronounced in early-weaned piglets and under poorer health conditions. Little interaction between plasma protein and antibiotics has been found, suggesting distinct modes of action and additive effects. Bovine colostrum may act more or less similarly to SDP. The composition of essential oils is highly variable, depending on environmental and climatic conditions and distillation methods. These oils differ widely in their antimicrobial activity in vitro and some components of weaning diets may decrease their activity. Results in young pigs are highly variable depending upon the product and doses used. These studies suggest that relatively high concentrations of essential oils are needed for beneficial effects to be observed and it has been assumed that these plant extracts mimic most of the effects of antibiotics active on gut physiology, microbiology and immunology. Often, bioactive substances protective to the gut also stimulate feed intake and growth performance. New insights on the effects of selected OA and AA, protein sources (especially SDP, bovine colostrum) and plant extracts with anti-bacterial activities on the gut are reported in this review.

Effects of dietary benzoic acid and sodium-benzoate on performance, nitrogen and mineral balance and hippuric acid excretion of piglets

The objective of this study was to compare the effects of sodium-benzoate (NaB) with those of benzoic acid (BAc) on growth performance of piglets as well as nutrient digestibility, nitrogen and mineral balance, urinary pH, and the urinary excretion of BAc and hippuric acid (HAc). The study was conducted with 120 weaning piglets (6.5 kg body weight), divided in four groups (15 replicates of two piglets each), which received (1) a basal diet (Control), or the basal diet supplemented with (2) 4 g NaB per kg (Group 4NaB), (3) 3.5 g BAc per kg (Group 3.5BAc) or (4) 5 g BAc per kg (Group 5BAc). Performance data were monitored over a 42-day period. Urine and faeces were collected from day 28-33 in metabolic cages with five piglets per treatment. Piglets of Groups 3.5BAc and 5BAc had similarly a considerably improved average daily gain and feed intake (p < 0.05). Performance of Group 4NaB was not significantly different from the other groups. Compared to the Control, the nitrogen retention was only improved in Group 5BAc (p < 0.05); the other groups showed intermediate values. In the supplemented groups, most of the BAc was excreted as HAc in urine, but only Groups 3.5BAc and 5BAc had reduced urinary pH (p < 0.05). Daily intake and faecal and urinary excretion of P and Ca were not affected by the treatment. The molar excess of Na in Group 4NaB was reflected by higher renal excretion of Na compared to the other groups (p < 0.05).

Emissions of sulfur-containing odorants, ammonia, and methane from pig slurry: effects of dietary methionine and benzoic acid

Supplementation of benzoic acid to pig diets reduces the pH of urine and may thereby affect emissions of ammonia and other gases from slurry, including sulfur-containing compounds that are expected to play a role in odor emission. Over a period of 112 d, we investigated hydrogen sulfide (H(2)S), methanethiol (MT), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and dimethyl trisulfide (DMTS), as well as ammonia and methane emissions from stored pig slurry. The slurry was derived from a feeding experiment with four pig diets in a factorial design with 2% (w/w) benzoic acid and 1% (w/w) methionine supplementation as treatments. Benzoic acid reduced slurry pH by 1 to 1.5 units and ammonia emissions by 60 to 70% for up to 2 mo of storage, and a considerable, but transitory reduction of methane emissions was also observed after 4 to 5 wk. All five volatile sulfur (S) compounds were identified in gas emitted from the slurry of the control treatment, which came from pigs fed according to Danish recommendations for amino acids and minerals. The emission patterns of volatile S compounds suggested an intense cycling between pools of organic S in the slurries, with urinary sulfate as the main source. Diet supplementation with methionine significantly increased all S emissions. Diet supplementation with benzoic acid reduced emissions of H(2)S and DMTS compared with the control slurry and moderately increased the concentrations of MT. Sulfur gas emissions were influenced by a strong interaction between methionine and benzoic acid treatments, which caused a significant increase in emissions of especially MT, but also of DMDS. In conclusion, addition of 2% benzoic acid to pig diets effectively reduced ammonia volatilization, but interactions with dietary S may increase odor problems.

Molecular analysis of microbial community structure in the chicken ileum following organic acid supplementation

To compensate for possible decreases in animal production due to restrictions on the use of antibiotics as growth promoters, several non-antibiotic alternatives have been investigated. Organic acid supplementation (OAS) of feed or water has shown some promising results for affecting intestinal microbiota and reducing pathogenic bacteria in the gastrointestinal (GI) tract. However, few studies have explored the effects of OAS on microbial communities using objective molecular-based techniques. The aim of the present study was to characterize via 16S rRNA gene-based approaches responses of the intestinal microbiota after OAS in chicks. Newborn chicks were randomly divided in four treatments: (a) control (no antibiotic, no OAS); (b) antibiotic administration (bacitracin MD); (c) organic acid blend dl-2-hydroxy-4(methylthio) butanoic acid [HMTBA]; lactic, and phosphoric acid (HLP); and (d) organic acid blend HMTBA, formic, and propionic acid (HFP). Ileal contents and mucosal scrapings from 7 chicks/treatment/day were taken at 15, 22, and 29 days of age, and genomic DNA was isolated for the molecular analysis of the intestinal microbiota. The data demonstrate that HFP blend treatment for 29 consecutive days affected ileal microbial populations as indicated by community fingerprinting analysis (16S rRNA PCR-DGGE). In parallel, total bacterial and lactobacilli populations were increased by the HFP blend treatment as demonstrated by targeted qPCR analysis of 16S rRNA. In summary, the present data demonstrate that OAS, HFP blend treatment in particular, shifts intestinal microbiota, generates more homogenous and distinct populations, and increases Lactobacillus spp. colonization of the chick ileum.

Enumeration of some cultivable bacterial groups and characterization of some abiotic variables in the jejunoileal content of Prim'Holstein veal calves

A study was conducted to characterize the bacterial and biochemical composition of the jejunoileal content of veal calves and the effect of pre-slaughter fasting time. At 22 wk of age, 22 preruminant Prim'Holstein calves fed milk replacer and pellets (mainly composed of corn) were slaughtered at 6, 12, or 24 h after their last meal. Chyme samples were collected from the jejunoileal compartment just after slaughter, and pH and redox potential were immediately measured. Culture-based methods were used to determine the concentrations of total anaerobic microflora, lactate-utilizing bacteria, Bacteroides fragilis group, Lactobacilli, Bifidobacteria, Enterococci, and 2 potential pathogenic species, Escherichia coli and Clostridium perfringens. Concentrations of l-lactate, ammonia, and short-chain fatty acids (SCFA) were determined on frozen samples. The biochemical composition (DM, total protein, lactose, galactose, glucose, minerals, AA profile, and fatty acid profile) of the jejunoileal content was determined only on samples from the 6-h fasted group. Microflora concentrations were greater (P < 0.01) in the 6-h fasted group compared with the 12- and 24-h fasted groups, involving a decreased pH (P < 0.05) and greater lactate and SCFA concentrations, both linked directly to the fermentative state of the microorganisms. The 6-h fasted group showed the least interanimal variability in bacterial group levels, except for Cl. perfringens, which presented increased interanimal variability regardless of fasting time. At 6 h postprandial, the jejunoileal content of veal calves seemed to be in a stable state, allowing the creation of a database on its biochemical composition. This study is a key first step in the development of an in vitro system for modeling the jejunoileal ecosystem of veal calves. This model will provide a useful tool for assessing the effects of feed additives on intestinal microflora.