Lower Lactic Acid Concentration Research Articles

Impact of essential and optional ingredients on microbial and metabolic profiles of kimchi

This study aimed to examine the impacts of essential and optional ingredients on the microbial and metabolic profiles of kimchi during 100 days of fermentation, using a mix-omics approach. Kimchi manufactured without essential ingredients (e.g., red pepper, garlic, ginger, green onion, and radish) had lower lactic acid content. The absence of garlic was associated with a higher proportion of Latilactobacillus and Lactococcus, while the absence of red pepper was associated with a greater proportion of Leuconostoc than the control group. In addition, red pepper and garlic served as primary determinants of the levels of organic acids and biogenic amines. Sugar was positively correlated with the levels of melibiose, and anchovy sauce was positively correlated with the levels of amino acids such as methionine, leucine, and glycine. These findings contribute to a fundamental understanding of how ingredients influence kimchi fermentation, offering valuable insights for optimizing kimchi production to meet various preferences.

Acid preservation of the brown seaweed Saccharina latissima for food applications

Acidification of the brown seaweed species Saccharina latissima using lactic or citric acid was investigated as a preservation method to increase the shelf life prior to further processing for use in food applications. Cut seaweed biomass was mixed with seawater or acid solution prepared using seawater and stored at ambient temperature for a period of up to 56 days. The samples were assessed through compositional analysis, recording of biomass loss and calculation of compound retentions. In addition, the sensory properties of selected samples were assessed through descriptive analysis. Acid addition resulted in a drop in pH to the range 3.6 to 4.1 for all treatments where the pH remained stable throughout the storage period. For the sample preserved in seawater only, pH dropped from 7.3 to 4.3 during the storage period due to production of lactic acid by naturally occurring bacteria. All treatments resulted in biomass and loss of minerals (mainly K) and carbohydrates, which correlated positively with acid concentration with the exception for mannitol where the highest loss was found in the seawater-preserved sample. Samples with low concentration of lactic or citric acid had the lowest total mass loss and highest retention of dry matter. Increasing concentrations of lactic acid led to lower total remaining dry matter and lower compound retention. Finally, the sensory evaluation showed that the intensity of sour taste significantly differed between treatments which were otherwise characterized by high saltiness. Higher acid dose resulted in a more sour taste and lactic acid was perceived as less sour than citric acid. In addition, lower sourness correlated with a more intense saltiness. The sensory profiles were not significantly affected by storage time.

Dietary creatine nitrate enhances muscle creatine loading and delays postmortem glycolysis of broilers that experienced preslaughter transport.

This study investigated the attenuating effects of dietary creatine nitrate (CrN), a novel form of creatine, on energy expenditure and rapid glycolysis in pectoralis major (PM) muscle of broiler induced by preslaughter transport. A total of 288 Arbor Acres broilers (28 day old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 d, respectively. On the day of transportation, the broilers from basal diet group were divided into two equal groups: one group was transported for 0.5 h (Control group) and the other group was transported for 3 h (T3h group). Meanwhile, the birds from GAA and CrN supplementation groups were transported for 3 h (identified as GAA600, CrN300, CrN600, and CrN900 group, respectively). The results demonstrated that dietary supplementation of GAA or CrN from 28 to 42 d of age did not significantly affect the growth performance, carcass traits, and textural characteristics (P > 0.05) in PM muscle of transported broilers. Compared with T3h group, GAA600, CrN600, and CrN900 groups increased the pH45min (P < 0.01), and CrN600, CrN900 groups decreased the cooking loss (P < 0.05) of PM muscle. Meanwhile, the muscle of GAA600, CrN600, and CrN900 groups showed a higher glycogen content (P < 0.01) and a lower lactic acid content (P < 0.01). GAA600 and all CrN treatments enhanced muscle Cr content and reduced AMP/ATP ratio (P < 0.01). In addition, GAA600 and all CrN treatments downregulated the relative mRNA expression levels of LKB1 and AMPKα2 (P < 0.001) and the protein expression of p-AMPKαThr172 compared with the T3h group (P < 0.01). All CrN treatments showed lower protein expression levels of LKB1 and p-LKB1Thr189 than those of the T3h group (P < 0.05). In summary, dietary supplementation with GAA and CrN enhanced the content of muscle creatine, and inhibited transport-induced activation of LKB1/AMPK pathway, which is beneficial for delaying rapid muscle glycolysis and improving meat quality.

Re-ensiling and microbial inoculant use effects on the quality of maize silages exposed to air

Re-ensiling has increased worldwide due to the increase in marketing of silage between farms. However, litlle is known about the aerobic deterioration and microbial inoculants effect in this process. The aim of this study was to determine the re-ensiling and microbial inoculant use effects on the maize silage quality. Experimental treatments included maize silage exposed to air for zero or 18 h, with or without microbial inoculant use containing a mixture of Lactobacillus plantarum and Propionibacterium acidipropionici. The forage was ensiled in 20 plastic buckets (20 liters capacity) with five repetitions per treatment. The silos were opened after 116 days and the chemical composition, in vitro dry matter digestibility (IVDMD), fermentative parameters, microorganism counts, total dry matter (DM) losses and aerobic stability of silage were evaluated. Re-ensiling reduced the non-fibrous carbohydrates content by 14.8%, whereas it increased the neutral detergent fiber content by 6%. The IVDMD was reduced by 6.1% in re-ensiled silages. In addition, re-ensiling increased the losses due to gases, effluents, and total DM. Lower lactic acid content and higher acetic acid content in re-ensiled maize silages were also observed. However, IVDMD increased by 4.6% in inoculated silages. Re-ensiling reduced the nutritive value and IVDMD of maize silages and should be avoided in production systems. The microbial inoculant use was not effective in improving the re-ensiled silage quality, which does not justify its use in these conditions. Farms should avoid purchasing maize silage due to reduction in nutritional value in the re-ensiling process. However, in some cases where farms need to purchase silage for feeding planning, the time between silo opening and re-ensiling should be as short as possible to reduce nutrient loss. Furthermore, in this situation the inoculant use does not improve silage conservation, which makes its use unnecessary.

From Milk Kefir to Water Kefir: Assessment of Fermentation Processes, Microbial Changes and Evaluation of the Produced Beverages

The aim of the present study was to investigate the feasibly of using traditional milk kefir grains for the production of water kefir-like beverages and assess the changes in the physicochemical characteristics and the microbial populations of the fermented beverages. To this end, experiments of milk fermentation were primarily conducted at different temperatures and upon selection of the optimal, a gradual substitution of the substrate was performed by replacing milk from a sucrose-based solution. After the successful fermentation of the sucrose substrate, fruit juices were used as fermentation substrates. Sensory evaluation of the sugar-based beverages was also performed in order to access their acceptability for consumption. According to the results, the transition from milk to water kefir is indeed feasible, leading to the production of beverages with relatively higher ethanol concentrations (up to 2.14 ± 0.12% w/v) than milk kefir and much lower lactic acid concentrations (up to 0.16 ± 0.01% w/v). During the fermentation of the sugary substrates, yeasts seemed to be dominant over lactic acid bacteria, in contrast to what was observed in the case of milk kefir, where LAB dominated. The sensory evaluation revealed that all sugar-based beverages were acceptable for consumption, with the fruit-based ones obtaining, though, a better score in all attributes.

Assessment of the quality of different brands of commercial yoghurt sold in Wukari Metropolis, Taraba State-Nigeria

The study evaluated physico-chemical and sensory properties of commercial yoghurts sold in Wukari metropolis. Six brands of yoghurt samples from different batches (two taken from each brand) were purchased from supermarkets and market. A total of twelve samples were analyzed for their nutritive value and sensory quality. The consumer's acceptability of the commercial yoghurts was assessed organoleptically. The nutritive value of yoghurt was determined by pH, titratable acidity, moisture, total solids, solids-non-fats, total fats and ash. The results showed a decrease in the level of acidity. The yoghurt sold within the locality showed a lower lactic acid content below the minimum range of 0.7% required for a standard fermented yoghurt product. The moisture content of the samples of batch 1and 2 yoghurt ranged from 72.38 to 89.55% respectively. The high moisture content of yoghurt higher than 84% in some of the samples analyzed is likely to affect the texture and mouth feel of the yoghurt. The total solid-nonfat (SNF) content of the yoghurt samples ranged from 11.26% to 24.62%. It was observed that there is no consistency in the total solid-nonfat content of the yoghurt samples even in the same product and amongst the different commercial yoghurt products. The result of this research revealed that some commercial yoghurts products sold in Wukari metropolis do not conform to regulatory standard for yoghurt products in their lactic acid content (&gt;84%), higher total solid (&gt;24%), and the lack of consistencies in color, appearance, taste, and flavor affected their consumer acceptability.

The differences in energy metabolism and redox status between sows with short and long farrowing duration

Farrowing duration is a crucial factor affecting survival of piglets and health of sows, and is highly correlated with the incidence of stillbirth. The present study assessed the metabolic characteristics of sows with short farrowing duration (SFD) or long farrowing duration (LFD). A total of 20 Yorkshire sows were screened from 60 sows and were retrospectively allocated into SFD (211 min on average, n = 10) or LFD (388 min on average, n = 10) group. Parameters associated with energy metabolism and redox status were characterised. Results showed that sows at farrowing had decreased plasma concentrations of glucose, triglyceride, acetate, butyrate and total short-chain fatty acids (P < 0.05), but increased concentrations of lactic acid and propionate (P < 0.05), when compared with sows on day 107 of gestation. The SFD sows had shorter time from last meal until the onset of farrowing (P < 0.05) and tended to have less stillbirths (P = 0.08) and lower stillbirth rate (P = 0.07). For the blood metabolites, SFD sows at farrowing had higher concentration of plasma glucose (P < 0.05), but lower concentration of lactic acid (P < 0.05) than LFD sows. Besides, SFD sows tended to have higher plasma malondialdehyde concentration (P = 0.06) than LFD sows. Correlation analysis showed that farrowing duration was negatively correlated with plasma glucose concentration at onset of farrowing. In conclusion, our study strongly suggests that glucose is a key metabolite for energy metabolism of the uterus during farrowing. The farrowing process could be closely related to uterine energy expenditure, and sows with shorter farrowing duration could be resulting from the shorter time from last meal until the onset of farrowing, associated with a greater proportion of energy from glucose.

Влияние низкомолекулярных пептидов, выделенных из кобыльего молока, на работоспособность крыс при физической нагрузке

In an experiment on rats on the «Treadmill running» model, the performance indicators were studied, as well as the state of the antioxidant defense system, including the level of under-oxidized products in the blood serum, erythrocyte membranes and the mitochondrial fraction of the femoral muscle of animals against the background of 28-day intake of the fraction of non-molecular peptides isolated from mare's milk. In the experimental group, in comparison with the control animals, the running time on the treadmill on the 28th day increased by 73.5 %, while a positive trend of increasing the run time has been noted since the seventh day of training, gradually increasing to the 28th day of the training. The intake by animals of the enriched fraction of low molecular weight peptides against the background of physical activity was accompanied by a decrease in the MDA level in the membranes of erythrocytes by 25.3 %, and diene conjugates by 33.8 %, as well as the activation of superoxide dismutase and catalase in the membranes of erythrocytes. A similar change was found in the mitochondrial fraction of the femoral muscle of animals. The experimental group of rats showed a lower concentration of lactic acid in the blood serum by 40.6 %; and in the femoral muscle by 24.7 %. Pyretic acid content was not different from the initial values. These results substantiate the usefulness of low molecular weight peptides in the design of specialized products and dietary supplements for sports nutrition.

Abundance and diversity of epiphytic microbiota on forage crops and their fermentation characteristic during the ensiling of sterile sudan grass.

This study aimed to evaluate the effects of exogenous epiphytic microbiota inoculation on the fermentation quality and microbial community of sudan grass silage. Gamma irradiated sudan grass was ensiled with distilled water (STR), epiphytic microbiota of sudan grass (SUDm), forage sorghum (FSm), napier grass (NAPm) and whole crop corn (WCCm). The FSm inoculated silage have significantly lower lactic acid (LA) concentration and higher pH during early ensiling, while LA concentration gradually and significantly increased with the progression of ensiling and have lower pH in relation to other treatments for terminal silage. Inoculation of NAPm resulted in lower LA and higher acetic acid (AA) concentrations, higher pH, ammonia-N and dry matter losses for terminal silage, followed by SUDm silage. Inoculations of WCCm significantly increased LA production and pH decline during early ensiling and have higher LA and pH then NAPm and SUDm silages during final ensiling. The early fermentation of SUDm silage was dominated by genus of Pediococcus. The genera of Lactobacillus were predominant in WCCm and NAPm silages during 3days of ensiling, while Weissella dominated initial microbial community of FS silage. The terminal silage of NAPm was dominated by Enterobacter and Rosenbergiella, while Enterobacter and Lactobacillus dominated terminal SUDm silage. The final silage of FSm was dominated by Lactobacillus, Weissella and Pediococcus, while Lactobacillus and Acetobacter dominated terminal WCCm silages. The results demonstrated that among the four forages the epiphytic microbiota from forage sorghum positively influenced the microbial community and fermentability of sudan grass silage.

Effect of lactic acid stress on biofilm formation of Escherichia coli O26 at different temperatures

AbstractSimilar to Escherichia coli O157, non‐O157 also inherits certain acid resistance, and its stress response can be induced under acidic conditions, which may be affected by temperature. In this study, O26, the main serotype of non‐O157 E. coli, was investigated in order to evaluate the effect of lactic acid stress on its biofilm formation (BF) at different temperatures. Firstly, the BF ability of 22 isolates of E. coli O26 were compared by means of crystal violet staining and the result showed that all strains had certain BF ability with variation among strains. Then, the strain 126Z with strong capacity and strain G13Z2 with medium capacity were selected for BF experiment in acidic TSB (pH 4.0 and 5.0, adjusted with lactic acid) at 15°C and 25°C, respectively. The results showed that the BF of O26 was decreased with increasing concentration of lactic acid, and the higher the concentration of lactic acid was, the less the amount of biofilm formed. Moreover, the effect of temperature on BF of different capacity strains was related to the pH value, that is, with a lower concentration of lactic acid, the higher the temperature was, the faster the biofilm amount increased. Under a higher acid concentration, the BF of two strains showed different dynamic changes and were inhibited in the later stage, in which the biofilm amount of 126Z decreased significantly at 15°C, while that of G13Z2 decreased more significant at 25°C. This observation was further confirmed by scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). This finding suggests that combined temperature and lactic acid intervention may be an effective method to prevent BF, and the results of present work would provide scientific basis for the risk assessment of E. coli O26 in food processing.

Sequencing and microbiota transplantation to determine the role of microbiota on the fermentation type of oat silage

This study was aimed to assess the effects of exogenous microbiota on fermentation quality and bacterial community dynamics in oat (OT) silage. The irradiated OT was treated with the following: (i) sterile water (STOT); (ii) epiphytic microbiota on oat (OTOT); (iii) epiphytic microbiota on maize (OTMZ); (iv) epiphytic microbiota on sorghum (OTSG). γ-Ray irradiation, microbiota transplantation and sequencing methods were firstly used. After 60 days of ensiling, OTMZ group had higher lactic acid (LA) and lower acetic acid (AA) contents than OTOT group. Inversely, lower LA content and higher ratio of LA to AA was observed in OTSG group than OTOT group. Lactobacillus was predominant in OTMZ-60 group, while Lactobacillus and Enterobacteriaceae were both dominant in OTSG-60 group. Overall, the higher amounts of Enterobacteriaceae and heterofermentative Lactobacillus are conductive to acetic acid-type fermentation, and forage microbiota transplantation may be a potential way to identify the role of microbe during ensiling.

Effect of Amniotic Injection of N-Carbamylglutamate on Meat Quality of Broilers.

Simple SummaryN-carbamylglutamate (NCG) is a key activator of endogenous arginine production, which plays a vital role in meat quality and antioxidant performance. To the best of our knowledge, there is no study about NCG enhancing the meat quality of broilers. The present research was aimed at exploring the effects of amniotic injection of NCG on meat quality of pectoral muscle in broilers. The data showed that the in ovo feeding (IOF) of NCG enhanced the arginine content, improved the nutritional properties, enhanced the antioxidant capacity, and improved the meat quality in the pectoral muscle of broilers. In summary, amniotic injection of NCG on day 17.5 of incubation could be an effective and novel approach to improving the meat quality of broilers.The current study was performed to determine the influence of amniotic injection of N-carbamylglutamate (NCG) on meat quality of pectoral muscle in broilers. A total of 792 alive broiler embryos at 17 d of incubation were assigned to three treatments randomly (non-injected control, saline-injected control, or NCG-injected treatment). The two injection treatments were an injection with 0.1 mL 0.85% aseptic saline alone or containing 2 mg NCG per egg at 17.5 d of incubation. After hatching, 72 healthy male chicks were selected from each treatment and housed in six pens for a 42 day feeding study. Pectoral muscles from six 42-day-old broilers were collected from each treatment group and were dissected for meat quality assays. The results showed that arginine contents in pectoral muscle in either free or hydrolytic form in the NCG group were higher than those in the non-injection control group (p < 0.05). In comparison to the non-injection or saline-injection control groups, NCG injection resulted in a lower lactic acid content in pectoral muscle (p < 0.05). Muscular antioxidant capacity in the NCG group was higher, as evidenced by the higher activity of catalase and glutathione peroxidase and lower content of malondialdehyde (p < 0.05). In addition, the group of in ovo administration of NCG had decreased drip loss and increased crude fat content in pectoral muscle in comparison to those of either control group (p < 0.05) and had enhanced crude protein content compared to that of the saline-injection control group (p < 0.05). Briefly, these results indicate that amniotic administration of NCG in the late incubation phase increased the arginine content, improved the nutritional properties, enhanced the antioxidant capacity, and improved the meat quality in the pectoral muscle of broilers. Amniotic injection of NCG may serve as a novel approach to improving the meat quality of broilers.

A polydiacetylene-based colorimetric sensor as an active use-by date indicator for milk

Current food date marking tools fail to take into account variables that impact shelf life, leading to food waste and posing human health risks. Herein, we develop a polydiacetylene/zinc oxide (PDA/ZnO) colorimetric sensor that can indicate milk freshness in real time. The PDA/ZnO system is engineered to indicate the freshness of full cream milk by monitoring its pH based on lactic acid concentration, an indicator of bacterial spoilage. The sensitivity is tuned by selection of the diacetylene monomers from which it is composed. Designs constructed from shorter chain diacetylenes are found to undergo chromatic transitions at a lower lactic acid concentration. Two new methods to tune PDA/ZnO sensitivity to lactic acid are explored, including relocation of the diacetylene functional group and lipid doping. A system constructed from 5,7-hexadecadiynoic acid (HDDA) and ZnO can discriminate between fresh (pH 6.8–6.0), spoiling (pH 6.0–4.5), and spoiled milk (pH 4.5–4.0) by a respective blue to purple to red color change. The chromatic stability of the PDA/ZnO sensor in food is studied as previous reports have shown the system to be unstable. We present a new method that stabilizes the nanocomposite by pre-exposure to the food matrix prior to photopolymerization.

Distinct Immune Responses Elicited From Cervicovaginal Epithelial Cells by Lactic Acid and Short Chain Fatty Acids Associated With Optimal and Non-optimal Vaginal Microbiota.

Non-optimal vaginal microbiota, as observed in bacterial vaginosis (BV), is typically characterized by a depletion of beneficial lactobacilli and an abundance of numerous anaerobes. These non-optimal conditions are associated with subclinical cervicovaginal inflammation and an increased risk of HIV infection compared to women colonized with optimal vaginal microbiota dominated by lactobacilli. Lactic acid (LA) is a major organic acid metabolite produced by vaginal lactobacilli that elicits anti-inflammatory effects from cervicovaginal epithelial cells and is dramatically depleted during BV. However, it is unclear if LA retains its anti-inflammatory activity in the presence of vaginal microbiota metabolites comprising short chain fatty acids (SCFAs) and succinic acid, which are also produced by an optimal vaginal microbiota. Furthermore, the immunomodulatory effect of SCFAs and succinic acid on cervicovaginal epithelial cells at higher concentrations present during BV is unknown. Here we report that in the presence of physiologically relevant concentrations of SCFAs and succinic acid at pH 3.9 (as found in women with lactobacillus-dominated microbiota) LA induced an anti-inflammatory state in cervicovaginal epithelial cells and inhibited inflammation elicited by the toll-like receptor (TLR) agonists polyinosinic:polycytidylic acid and Pam3CSK4. When cervicovaginal epithelial cells were treated with a vaginal microbiota metabolite mixture representative of BV, containing a lower concentration of LA but higher concentrations of SCFA/succinic acid at pH 7, no anti-inflammatory was observed. Rather, the vaginal microbiota metabolite mixture representative of BV dysregulated the immune response of cervicovaginal epithelial cells during prolonged and sustained treatments. This was evidenced by increased basal and TLR-induced production of pro-inflammatory cytokines including tumor necrosis factor-α, but decreased basal production of chemokines including RANTES and IP-10. Further characterization of individual components of the BV vaginal microbiota mixture suggested that acetic acid is an important vaginal microbiota metabolite capable of eliciting diverse immunomodulatory effects on a range of cervicovaginal epithelial cell targets. These findings indicate that elevated levels of SCFAs are a potential source of cervicovaginal inflammation in women experiencing BV, and support the unique anti-inflammatory properties of LA on cervicovaginal epithelial cells as well as a role for LA or LA-producing lactobacilli to reverse genital inflammation associated with increased HIV risk.

Resting Energy Expenditure and Substrate Oxidation in Malnourished Patients With Type 1 Glycogenosis.

Type 1a and 1b glycogenosis [glycogen storage disorder (GSD)1a, GSD1b] are rare diseases generally associated with malnutrition. Although abnormal substrate oxidation rates and elevated energy expenditures might contribute to malnutrition, this issue has not been investigated. To investigate whether abnormal resting energy expenditure (REE) and substrate oxidation rate characterize patients with GSD1. Cross-sectional study. Outpatient referral center for rare diseases and laboratory of clinical nutrition at the University Hospital of Palermo. Five consecutive patients with GSD1 (4 type a, 1 type b; 3 men, 2 women; age range, 19 to 49 years). The usual clinical procedures for patients with malnutrition, including REE and basal substrate oxidation rate (both indirect calorimetry), body composition (bioimpedance method), muscle strength (hand-grip test), and the usual laboratory tests, were performed. Malnutrition was clearly diagnosed in 2 patients (1 GSD1a and 1 GSD1b), with REE elevated in all five patients, and especially, in the two malnourished patients (+124% and +32.1% vs predictive values using Harris-Benedict equations). The two malnourished patients also exhibited lower basal protein oxidation rates (7.7% and 6.6%) than the nourished patients (range, 12.1% to 24.7%), with higher carbohydrate or lipid oxidation rates. Additionally, the two malnourished patients exhibited higher blood concentrations of lactic acid than the nourished patients. According to data obtained from our small sample of patients with GSD1, elevated REEs seem to be a common characteristic that might contribute to malnutrition. Low basal protein oxidation rates and elevated blood lactic acid concentrations appear to be associated with malnutrition.

Potential Application and Bactericidal Mechanism of Lactic Acid-Hydrogen Peroxide Consortium.

It has been found that lactic acid and hydrogen peroxide (H2O2) displayed co-operatively enhanced killing activity to pathogens. The synergistic effect was investigated with using several microbe species, suggesting that low concentration of lactic acid and H2O2 could kill both Gram-negative and Gram-positive bacteria or even fungal pathogens. To explore the mechanism of synergistic sterilization of lactic acid and H2O2, Escherichia coli DH5α was used as the indicator bacteria. Lactic acid and H2O2 could generate hydroxyl radicals depending on the intracellular iron ions. The genomic DNA of treated cells was fractured and dispersed, and the △recA strain was more susceptive to the treatment, indicating that DNA damage was a cause of cell death. Furthermore, serious leakage of cell contents occurred in the treated cell, suggesting that the treatment also resulted in cell membrane permeability changes. This research shows that lactic acid-H2O2 consortium is a hopeful safety bactericide in agriculture or food production processes and provides a greater understanding of the mechanism of synergistic sterilization of lactic acid-H2O2 consortium in vivo.

Characteristics of proteolytic microorganisms and their effects on proteolysis in total mixed ration silages of soybean curd residue.

ObjectiveThe objective of this study was to isolate proteolytic microorganisms and evaluate their effects on proteolysis in total mixed ration (TMR) silages of soybean curd residue.MethodsTMRs were formulated with soybean curd residue, alfalfa or Leymus chinensis hay, corn meal, soybean meal, a vitamin-mineral supplement, and salt in a ratio of 25.0: 40.0:30.0:4.0:0.5:0.5, respectively, on a basis of dry matter. The microbial proteinases during ensiling were characterized, the dominate strains associated with proteolysis were identified, and their enzymatic characterization were evaluated in alfalfa (A-TMR) and Leymus chinensis (L-TMR) TMR silages containing soybean curd residue.ResultsBoth A-TMR and L-TMR silages were well preserved, with low pH and high lactic acid concentrations. The aerobic bacteria and yeast counts in both TMR silages decreased to about 105 cfu/g fresh matter (FM) and below the detection limit, respectively. The lactic acid bacteria count increased to 109 cfu/g FM. The total microbial proteinases activities reached their maximums during the early ensiling stage and then reduced in both TMR silages with fermentation prolonged. Metalloproteinase was the main proteinase when the total proteinases activities reached their maximums, and when ensiling terminated, metallo and serine proteinases played equally important parts in proteolysis in both TMR silages. Strains in the genera Curtobacterium and Paenibacillus were identified as the most dominant proteolytic bacteria in A-TMR and L-TMR, respectively, and both their proteinases were mainly with metalloproteinase characteristics. In the latter ensiling phase, Enterococcus faecium strains became the major sources of proteolytic enzymes in both TMR silages. Their proteinases were mainly of metallo and serine proteinases classes in this experiment.ConclusionProteolytic aerobic bacteria were substituted by proteolytic lactic acid bacteria during ensiling, and the microbial serine and metallo proteinases in these strains played leading roles in proteolysis in TMR silages.

Effects of offering lupins/triticale and vetch/barley silages alone or in combination with grass silage on animal performance, meat quality and the fatty acid composition of lean meat from beef cattle

AbstractAn experiment was carried out to examine the effects of offering beef steers grass silage (GS) as the sole forage, lupins/triticale silage (LTS) as the sole forage, a mixture of LTS and GS at a ratio of 70:30 on a dry matter (DM) basis, vetch/barley silage (VBS) as the sole forage, a mixture of VBS and GS at a ratio of 70:30 on a DM basis, giving a total of five silage diets. Each of the five silage diets was supplemented with 2 and 5 kg of concentrates/head/day in a 5 × 2 factorial design to evaluate the five silages at two levels of concentrate intake and to examine possible interactions between silage type and concentrate intake. A total of 80 beef steers were used in the 122-day experiment. The GS was well preserved while the whole crop cereal/legume silages had high ammonia-nitrogen (N) concentrations, low lactic acid concentrations and low butyric acid concentrations For GS, LTS, LTS/GS, VBS and VBS/GS, respectively, silage DM intakes were 6.5, 7.0, 7.2, 6.1 and 6.6 (s.e.d.0.55) kg/day and live weight gains were 0.94, 0.72, 0.63, 0.65 and 0.73 (s.e.d.0.076) kg/day. Silage type did not affect carcass fatness, the colour or tenderness of meat or the fatty acid composition of the intramuscular fat in thelongissimus dorsimuscle.

Influences of addition of malic acid or citric acid, Lactobacillus plantarum and their mixtures on fermentation quality, proteolysis and fatty acid composition of ensiled alfalfa

ABSTRACTThe aim of this study was to evaluate the effect of two organic acids [malic acid (MA) and citric acid (CA)], Lactobacillus plantarum (LP) and their mixtures on the fermentation of alfalfa silage. The wilted and chopped alfalfa was ensiled in vacuum-sealed plastic bags (200–230 g per bag) with following additives: 0.5% distilled water (control), 0.5% DL-MA, 0.5% CA, LP (1 · 106 cfu/g), 0.5% DL-MA plus LP (MA+LP) or 0.5% CA plus LP (CA+LP) (application rates based on fresh weight). Each treatment had four replicates and was stored at room temperature. After 60 d of ensiling, decreases in pH, non-protein N (NPN) and increases in lactic acid were observed in all additive-treated silages (p < 0.01). Compared with treatment LP, higher pH and lower lactic acid concentrations were observed after MA or CA addition (p < 0.05) and further application of MA or CA together with LP did not promote lactic acid fermentation in ensiled alfalfa. Furthermore, additives decreased the proportion of saturated fatty acids and increased the proportion of polyunsaturated fatty acids in ensiled alfalfa, with the highest level in CA-treated silages (p < 0.05). Although MA and CA were not as effective as LP in improving silage fermentation quality, treatments MA+LP and CA+LP were more effective in decreasing silage NPN, and CA was most effective in inhibiting biohydrogenation of fatty acids in ensiled alfalfa.

Characterization of Tifton 85 bermudagrass haylage with different layers of polyethylene film and storage time.

ObjectiveThe objective was to characterize the fermentative and microbiological profile of Tifton 85 bermudagrass haylage with different layers of polyethylene film and storage time.MethodsThe experimental design consisted of a randomized block design with four and six wrapping layers (100 and 150 microns in total. respectively) allocated in the main plots, through repeated measures analysis (30, 60, and 90 days of storage) with four replicates.ResultsThe storage time and number of wrapping layers did not show changes in the population of Clostridium and lactic acid bacteria. A decrease was observed in the enterobacteria population with an increase in the storage period in the two wrapping layers studied. Upon opening of the haylage at 30 days, the population of Bacillus was lower in haylages made with six layers of wrapping (3.63 log colony forming units/g). No growth of Listeria sp. or Salmonella sp. was observed during the experimental period. The fungal genera with a greater occurrence were Penicillium sp. and Fusarium sp. The following mycotoxins were not detected: ochratoxin A, fumonisins, and zearalenone. Relative to the organic butyric, propionic, and acetic acids, the haylages presented a low concentration of lactic acid; this may have prevented a drop in the pH, which was high when the silos were opened (5.4). The levels of ammoniacal nitrogen and soluble carbohydrates presented no variation among the number of wrapping layers, with an overall average of 35.55 and 38.04 g/kg.ConclusionTifton 85 bermudagrass haylage wrapped with four and six layers presented adequate fermentation and microbiological characteristics in the evaluated periods.