Anaerobic lactic acid degradation during ensilage of whole crop maize inoculated with lactobacillus buchneri inhibits yeast growth and improves aerobic stability

Aerobic deterioration of silages is initiated by (facultative) aerobic micro-organisms, usually yeasts, that oxidize the preserving organic acids. In this study, a Lactobacillus buchneri strain isolated from maize silage was evaluated for its potential as a bacterial inoculant that enhances aerobic stability of silages. In four experiments, chopped whole crop maize (30-43% dry matter (DM)) was inoculated with Lact. buchneri and ensiled in laboratory silos. Uninoculated silages served as controls. Analysis of silages treated with Lact. buchneri at levels of 103-106 cfu g-1 after about 3 months of anaerobic storage showedthat acetic acid and 1-propanol contents increased with inoculum levels above 104 cfu g-1,whereas lactic acid decreased. Propionic acid, silage pH and DM loss increased withinoculum levels above 105 cfu g-1. Time course experiments with maize inoculated with Lact. buchneri at 4 x 104-2 x 105 cfu g-1 showed that up to 7-14 d after ensiling, Lact. buchneri had no effect on silage characteristics. Thereafter, the lactic acid content of the inoculated silages declined and, simultaneously, acetic acid and, to a lesser extent, propionic acid and 1-propanol, accumulated. Inoculation reduced survival of yeasts during the anaerobic storage phase and inhibited yeast growth when the silage was exposed to O2, resulting in a substantial improvement in aerobic stability. The results indicate that the use of Lact. buchneri as a silage inoculant can enhance aerobic stability by inhibition of yeasts. The ability of the organism to ferment lactic acid to acetic acid appears to be an important underlying principle of this effect.     

The role of Lactobacillus buchneri in forage preservation

In 1996 Wienberg and Muck proposed to implement Lactobacillus buchneri in silage starters. The main reason for the use of heterofermentative lactic acid bacteria is the increased stability of silages against deterioration by yeasts and moulds when exposed to air. In the following years, the unique activity of L. buchneri in silages was evaluated. It was proven that acetic acid formed from lactic acid by L. buchneri is solely responsible for the increased stability of silages. Recently, a novel metabolic pathway from lactic acid to acetic acid and 1,2-propanediol was proposed.     

Effects of <Emphasis Type="Italic">Lactobacillus buchneri</Emphasis> and <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> on fermentation,aerobic stability,bacteria diversity and ruminal degradability of alfalfa silage

Silages are important feedstuffs. Homofermentative lactic acid bacterial inoculants are often used to control silage fermentation. However, some research pointed out those homofermentative lactic acid bacteria (LAB) impaired the aerobic stability of wheat, sorghum, and corn silages. Adding heterofermentative LAB can produce more acetic acid, thereby stabilizing silages during aerobic exposure. Alfalfa is difficult to ensile. The present work was to study the effects of L. buchneri (heterofermentative LAB), alone or in combination with L. plantarum (homofermentative LAB) on the fermentation, aerobic stability, bacteria diversity and ruminal degradability of alfalfa silage. After 90 days ensiling, the pH, NH₃-N/TN, butyric acid content and molds counts of control were the highest. The inoculated silages had more lactic acid, acetic acid content and more lactic acid bacteria than the control. Inoculating LAB inhibited harmful microorganisms, such as Enterobacterium and Klebsiella pneumoniae. The L. buchneri + L. plantarum-inoculated silage had more acetic acid and less yeasts than other three treatments (P < 0.05), and lower NH₃-N/TN than control (P < 0.05). The CO₂ production of L. buchneri + L. plantarum-inoculated silage was less than that of L. plantarum-inoculated silage (P < 0.05). Inoculating LAB in alfalfa silages can decrease pH, increase the production of lactic and acetic acids, reduce the number of yeasts and molds, and inhibit Enterobacterium and K. pneumoniae. Inoculating with L. buchneri or L. buchneri + L. plantarum can improve aerobic stability of alfalfa silages. A combination of L. buchneri and L. plantarum is preferable because it enhanced alfalfa silage quality and aerobic stability.     

The effect of applying lactic bacteria at ensilage on the chemical and microbiological composition of vetch, wheat and alfalfa silages

The effect of applying a commercial lactic acid bacterial inoculant, at 5.6 × 10⁴ cfu/g fresh material, to vetch, wheat, direct-cut and wilted alfalfa silages has been studied under laboratory conditions, and on wheat also under farm conditions. Dry matter losses in the inoculated vetch and alfalfa silages were smaller than in the control silages, due to improved fermentation in the former as indicated by a faster and larger pH decrease and by a faster and larger lactic acid build-up. Volatile fatty acid analysis also indicated more efficient fermentation patterns in the inoculated vetch and alfalfa silages with less ethanol, acetic and butyric acids compared with the respective control silages. The inoculant suppressed enterobacteria and clostridia in the inoculated direct-cut alfalfa silage. The inoculant did not have a great effect on the wheat silages.     

Effect of NaCl-tolerant lactic acid bacteria and NaCl on the fermentation characteristics and aerobic stability of silage

NaCl-tolerant lactic acid bacteria (LAB) strains LC-10 ( Lactobacillus casei ) and LP-15 ( Lact. plantarum ) and NaCl were used as additives to sorghun ( Sorghum bicolor ). Numbers of LAB were significantly ( P < 0·05) higher in all the additive-treated silages than in the control silage at an early stage of ensiling. During the fermentation process, addition of NaCl or LAB effectively inhibited the growth of aerobic bacteria and clostridia, but not yeasts. All the additive-treated silages had significantly ( P < 0·05) lower pH, ammonia nitrogen content, dry matter loss and gas production but significantly ( P < 0·05) higher lactic acid content and residual water soluble carbohydrates compared with the control silage. The improvement in silage quality was in the order : LAB > NaCl > control. Yeast counts were high in all additive-based silages and they increased during the exposure of the silages to air. As a result, these silages suffered aerobic deterioration, whereas the control silage was stable. The results confirmed that the NaCl or LAB improved fermentation quality but did not prevent aerobic deterioration of the silage.     

Alcoholic fermentation and its prevention by Lactobacillus buchneri in whole crop rice silage

AIMS: To evaluate the fermentation characteristics and the effects of Lactobacillus buchneri inoculation in ensiling whole crop rice. METHODS AND RESULTS: Laboratory-scale silages were prepared from whole crop rice harvested at yellow-ripe stage. The crop was ensiled for 2 months with and without inoculation of L. buchneri at 10(4), 10(5) and 10(6) CFU g(-1). The effect of prolonged ensiling was also studied by using the same crop; the silos were opened at 1, 3, 6 and 12 months, while the inoculation was made at 10(5) CFU g(-1). Enhanced alcoholic fermentation was found in untreated silage; the sum of ethanol and 2,3-butanediol were seven times higher at 2 months than those of lactic and volatile fatty acids, while the differences were diminished at 12 months owing to the reduction of ethanol in the late ensiling period. Inoculation of L. buchneri inhibited the alcohols; however, ethanol yet prevailed over the fermentation until 6 months, after which acetic acid became the main product in the inoculated silage. Regardless of inoculation and ensiling period, yeasts were not found in whole crop rice silage. CONCLUSIONS: Substantial amounts of ethanol and 2,3-butanediol would be produced in silage prepared from whole crop rice. The alcoholic fermentation can be suppressed when inoculated with L. buchneri. SIGNIFICANCE AND IMPACT OF THE STUDY: Inoculation of L. buchneri could be an option to prevent ethanol fermentation in silage.     

Identification and properties of yeasts associated with the aerobic deterioration of wheat and alfalfa silages

Populations of fungi in aerobically deteriorating wheat and alfalfa silages were identified as: Endomycopsis burtonii, E. selenospora, Hansenula canadensis, Candida tenuis and C. silvicola. The yeasts recovered were similar for both silages, but H. canadensis was recovered only in wheat silages. All of these yeasts could utilize lactic acid aerobically, but not anaerobically. Only Endomycopsis spp. could utilize propionic acid aerobically and none of the yeasts utilized this acid anaerobically. However, all yeasts grew in complete media supplemented with propionate. Therefore, while lactic and propionic acids may contribute to stability under anaerobic conditions, they are much less less effective after the silage is exposed to air.     

The effect of Lactobacillus buchneri and L. plantarum, applied at ensiling, on the ensiling fermentation and aerobic stability of wheat and sorghum silages

The effect of applying Lactobacillus buchneri (LB), alone or in combinations with L. plantarum (LP) and yeasts at ensiling, on the ensiling fermentation and aerobic stability of wheat and sorghum silages was studied under laboratory conditions. Treatments comprised LB, LP, yeasts, LB + yeasts, LP + yeasts, LB + LP and B-589 (a lactic acid bacterial strain isolated from wheat silage in Israel) alone. The treatments were also applied to sterilized aqueous extracts of wheat which were incubated at 30°C for 10 days. The pH of all treatments was below 4.0 already on day 4 of the experiment. Silages treated with LB had higher acetic acid concentrations than those treated with LP: 32–34 vs 16–18, and 28–34 vs 4–7 g kg⁻¹ in the experiments with wheat and sorghum, respectively. Similar results were obtained in wheat extracts. In the aqueous phase, marked differences in pH decrease were noticed among the treatments: 4.4 in LB, 6.0 in the yeast, and 3.7 in LP and B-589 (from day 3 and onwards). In both crops LB resulted in aerobically stable silages when applied alone or with LP and yeasts, whereas LP resulted in unstable silages upon aerobic exposure; the stability of the LB-treated silages is attributed to the higher acetic acid concentrations. The isolated strain (B-589) did not exhibit any advantage with regard to aerobic stability. Received 26 April 1999/ Accepted in revised form 05 July 1999     

The effect of Lactobacillus buchneri on the fermentation, aerobic stability and ruminal degradability of maize silage

AIMS: To evaluate the effect of Lactobacillus buchneri, heterofermentative lactic acid bacteria (LAB), on the fermentation, aerobic stability and ruminal degradability of whole-crop maize silages under laboratory conditions. Two homofermentative LAB were tested for the purpose of comparison. METHODS AND RESULTS: Maize was harvested at early dent [290 g kg(-1) dry matter (DM)] and one-half milk line (355 g kg(-1) DM) stages. Both homofermentative LAB were applied at 1 x 10(5) CFU g(-1) of fresh forage. Lactobacillus buchneri was applied at 1 x 10(5), 5 x 10(5) and 1 x 10(6) CFU g(-1) of fresh forage. Silages with no additives served as control. After treatment, the chopped forages were ensiled in 1.5-l anaerobic jars. Three jars per treatment were sampled on day 60. After 60 days of storage, silages were subjected to an aerobic stability test lasting for 5 days, in which CO(2) production, as well as chemical and microbiological parameters, was measured to determine the extent of aerobic deterioration. Both homofermentative LAB increased the concentration of lactic acid and the numbers of yeasts, and decreased the concentration of acetic acid and impaired the aerobic stability of silages. In contrast, applying L. buchneri decreased the concentration of lactic acid and increased the concentration of acetic acid of the silages. Under aerobic conditions, silages treated with 5 x 10(5) and 1 x 10(6) CFU g(-1) of L. buchneri, had lower pH, CO(2) production and the numbers of yeasts than the silages treated with 1 x 10(5) CFU g(-1) of L. buchneri (P < 0.05). However, all doses of L. buchneri and both homofermentative LAB did not affect in situ rumen DM, organic matter and neutral detergent fibre degradability of the silages. CONCLUSIONS: Lactobacillus buchneri was very effective in protecting maize silages exposed to air under laboratory conditions. All doses of L. buchneri, especially 5 x 10(5) CFU g(-1) or more, markedly decreased the numbers of yeasts and improved the aerobic stability of silages. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of L. buchneri, as a silage inoculant, can improve the aerobic stability of maize silages by inhibition of yeast activity.     

Accumulation of 1,2-propanediol and enhancement of aerobic stability in whole crop maize silage inoculated with Lactobacillus buchneri

Aims: To assess the effects of inoculation of Lactobacillus buchneri on the ensiling properties and aerobic stability of maize silage. Methods and Results: Chopped whole crop maize was ensiled in 0.5 litre airtight polyethylene bottles (0.4 kg per bottle) and in double-layered, thin polyethylene bags (15 kg per bag), with or without inoculation of Lact. buchneri. The silos were stored for two to four months and the chemical composition, microbial numbers and aerobic stability were determined. Inoculation lowered lactic acid and yeasts, and increased acetic acid and pH value, resulting in improved aerobic stability of the silages. Inoculated silages produced 1,2-propanediol, the content of which increased as ensiling was prolonged, and nearly 50 g kg-1 dry matter had accumulated after four months of storage. The effects of inoculation, however, were much less pronounced in silages prepared in bags. Mannitol was found in all silages; the production was lowered by Lact. buchneri treatment and appeared to be unrelated to the accumulation of 1,2-propanediol. Conclusions: Inoculation of Lact. buchneri occasionally causes accumulation of 1,2-propanediol in silages without further degradation into propionic acid and 1-propanol. Significance and Impact of the Study: Substantial amounts of 1,2-propanediol could be consumed by ruminants when fed on silages inoculated with Lact. buchneri. In addition to increasing acetic acid, attention needs to be paid to 1,2-propanediol because the two fermentation products might affect the intake and utilization of silage-based diets.     

Bacteriological and chemical changes occurring in Bunker-stored silage covered with biodegradable coating

AIMS: To evaluate the efficacy of a biodegradable silage coating for the ability to protect timothy (Phleum pratensa) type silage against spoilage and its quality under natural conditions. METHODS AND RESULTS: Triplicate mini-silos of silage were prepared for three treatments (1: uncoated; 2: coated with biodegradable coating and 3: sealed with plastic), two types of storage (unprotected or protected from rain) and 10 sampling times (0, 7, 14, 21, 28, 35, 42, 56, 63 and 70 days postensiling). Triplicate mini-silos were opened at each sampling time for microbiological (total aerobic bacteria, lactic acid bacteria, moulds and yeasts) and biochemical analyses [pH, dry matter (DM), water-soluble sugars (WSC), lactic (LA), acetic, propionic and butyric acids content]. The study showed that at day 70, counts of moulds and yeasts in silages protected against rain and coated with biodegradable coating were 5.98 log CFU g(-1) when compared with 5.92 and 3.62 log CFU g(-1) in samples from plastic-sealed silage and uncoated silage, respectively. The pH was low and stable pH (4.34) when compared with uncoated (7.17) and plastic sealed (8.34) silages (P < or = 0.05). A DM, WSC and LA content of 421.7, 13.4 and 20.9 g kg(-1) was, respectively, observed. For silage stored outdoors, a level of moulds and yeasts of 3.77 log CFU g(-1) of silage was also observed in silages coated with biodegradable coating after 28 days of storage. A stable pH showing a mean value of 4 was also observed. The pH, DM, WSC and LA content were, respectively, 4.18, 341.1, 13.34 and 31.8 g kg(-1) in these samples. After 70 days of storage, the level of moulds and yeasts on silage sealed with biodegradable coating was 7.73 log CFU g(-1). A DM, WSC and LA content of 291.9, 5.56 and 10.0 g kg(-1) was, respectively, observed. CONCLUSIONS: When compared with uncoated silage, the application of biodegradable coating can preserve the quality of silage for up to a month when exposed to rain and up to 70 days when protected from rain. SIGNIFICANCE AND IMPACT OF THE STUDY: Results emphasize the possibility of the use of a biodegradable coating as an alternative to plastic film for sealing horizontal bunker silos.     

Utilization of corn silage juice by Klyuveromyces marxianus

Corn silage juice was found to be a favorable substrate for production of fodder yeasts. Kluyveromyces marxianus NRRL Y-610 yielded significantly more cell dry weight than other cultures examined. In shake-flask experiments, the yeast produced over 13 g of cell dry weight per liter of corn silage juice and completely consumed the organic pollutants (lactic acid, acetic acid, and ethanol). The yeast settled rapidly and had a yeast volume index of 21 ml/g. The results indicate that K. marxianus NRRL Y-610 could be used to efficiently remove lactic acid and other organic compounds from corn silage juice with the concomitant production of fodder yeast.     

Enhancing Nutritional Quality of Silage by Fermentation with Lactobacillus plantarum

The present study was aimed to investigate the nutritive profiles, microbial counts and fermentation metabolites in rye, Italian rye-grass (IRG) and barley supplemented with Lactobacillus plantarum under the field condition, and its probiotic properties. After preparation of silage, the content of crude protein (CP), crude ash, acid detergent fiber (ADF), and neutral detergent fiber (NDF), microbes such as lactic acid bacteria (LAB), yeast and fungi counts, and fermentation metabolites lactic acid, acetic acid and butyric acid was assessed. Results indicated that the content of ADF and NDF were significantly varied between rye, IRG and barley mediated silages. The content of CP was increased in L. plantarum supplemented with IRG, but slightly decreased in rye and barley mediated silages. The maximum LAB count was recorded at 53.10 × 10⁷ cfu/g in rye, 16.18 × 10⁷ cfu/g in IRG and 2.63 × 10⁷ cfu/g in barley silages respectively. A considerable number of the yeasts were observed in the IRG silages than the rye silages (P < 0.05). The amount of lactic acid production is higher in L. plantarum supplemented silages as compared with control samples (P < 0.05). It was confirmed that higher amount of lactic acid produced only due to more number of LAB found in the silages. L. plantarum was able to survive at low pH and bile salt and the duodenum passage with the highest percentage of hydrophobicity. Furthermore, the strain was sensitive towards the antibiotics commonly used to maintain the microbes in food industrial setups. In conclusion, supplementation of L. plantarum is most beneficial in rye, IRG and barley silage preparations and probiotic characteristics of L. plantarum was an intrinsic feature for the application in the preparation of animal feeds and functional foods.     

Bacterial community associated with ensilage process of wilted guinea grass

Aims: To determine the effects of wilting, storage period and bacterial inoculant on the bacterial community and ensiling fermentation of guinea grass silage. Methods and Results: Fermentation products, colony counts and denaturing gradient gel electrophoresis (DGGE) profiles were determined. There was more lactic acid than acetic acid in all silages, but the lactic acid to acetic acid ratio decreased with storage time. This shift from lactic to acetic acid was not prevented even with a combination of wilting and bacterial inoculant. The DGGE analyses suggest that facultatively heterofermentative lactic acid bacteria (Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus pentosus) were involved in the shift to acetic acid fermentation. Conclusions: Lactic acid can dominate the fermentation in tropical grass silage with sufficient wilting prior to ensiling. Prolonged storage may lead to high levels of acetic acid without distinctive changes in the bacterial community. Significance and Impact of the Study: The bacterial community looks stable compared to fermentation products over the course of long storage periods in tropical grass silage. Acetic acid fermentation in tropical grass silage can be a result of the changes in bacterial metabolism rather than community structure.     

Fatty Acid and Isoprenoid Quinone Composition in the classification of Bacteroides melaninogenicus and Related Taxa

Aerobic deterioration of lucerne, maize and wheat silages was characterized by rapid increases in yeast and mould flora which oxidized lactic and volatile acids resulting in increased temperature and pH. While populations of yeasts and moulds were similar, temperature increases were slightly greater for silages inoculated with Lactobacillus acidophilus and Candida spp. After 48 h the pH of the inoculated silages was higher in general and concentrations of acids were lower than controls. Bacterial growth was slight although continued lactic acid production was probable. In contrast to lucerne and maize silages, the pH of wheat silage remained stable during this period because of high butyric levels, but temperature and yeast populations increased. After 48 h the pH rose above 5 in maize and lucerne, and bacterial growth and metabolic activity resumed resulting in volatile and non-volatile acid production from carbohydrate fermentation and deamination of amino acids. During this phase of aerobic deterioration yeast growth slowed or stopped, but temperatures remained high and pH continued to climb probably because of production of ammonia. The changes in gross composition of the silages did not follow any particular pattern. Losses in dry matter were small (2.5–4.0%) and changes in individual components probably reflect this loss rather than substantial changes. Protein availability in the lucerne silages undoubtedly decreased, as protein losses were high. It is concluded that the aerobic deterioration of silage is enhanced by the addition of L. acidophilus and Candida spp. at ensiling.     

New trends and opportunities in the development and use of inoculants for silage

Abstract: Inoculants are used as silage additives to improve preservation efficiency and to enhance animal performance. In most commercially available inoculants, homofermentative lactic acid bacteria (LAB) have been used because they are fast and efficient producers of lactic acid, improving natural silage fermentation. Specific LAB inuculants may also have beneficial effects on animal performance even if there is no effect on fermentation. However, these types of inoculants are not always advantageous. They do not necessarily prevent sermentation by clostridia in moist silages, and they sometimes impair the aerobic stability of grass and small grain silages. Therefore, new criteria for silage inoculants should be established which consider the specific needs of the crop being ensiled. New approaches which are being taken to develop improved inoculants for silage include the following: (1) using LAB isolates which are more specific to the target crops; (2) inclusion of heterofermentative LAB to produce volatile fatty acids to inhibit yeasts and moulds upon aerobic exposure; (3) inclusion of organisms other than LAB in inoculants to inhibit detrimental microorganisms; (4) selection or engineering of LAB strains to inhibit specific microorganisms; and (5) cloning and expression of genes which would enable selected LAB strains to utilize polysaccharides in crops which are low in soluble carbohydrates. Many of these new strategies for formulating inoculants are being tested, but further research is needed to determine the most successful approaches.     

Viability of Cryptosporidium parvum during ensilage of perennial ryegrass

The survival of Cryptosporidium parvum during ensilage of perennial ryegrass was examined in laboratory silos with herbage prepared in one of three different ways; either untreated, inoculated with a strain of Lactobacillus plantarum or by direct acidification with formic acid. The pH values of all silages initially fell below 4.5, but only formic acid-treated silage remained stable at less than pH 4 after 106 d, with the pH of the untreated and inoculant-treated silages rising to above 6. The formic acid-treated silage had a high lactic acid concentration (109 g kg^-1 dry matter (DM)) and low concentrations of propionic and butyric acids after 106 d. However, the untreated and inoculant-treated silages showed an inverse relationship, with low lactic acid concentrations and high concentrations of acetic, propionic and butyric acids. These silages also contained ammonia-N concentrations in excess of 9 g kg^-1 DM. In terms of the viability of Cryptosporidium parvum oocysts very few differences were seen after 14 d of ensilage with ca 50% remaining viable, irrespective of treatment and total numbers had declined from the initial level of 5.9 × 10⁴ to 1 x 10⁴ g^-1 fresh matter. Total oocyst numbers remained approximately the same until the end of the ensiling period, with the percentage of viable oocysts declining to 46, 41 and 32% respectively for formic acid, inoculant and untreated silages. The results are discussed in terms of changes occurring during the silage fermentation, in particular the products which may influence the survival of Cryptosporidium and implications for agricultural practice and the health of silage fed livestock.     

Lactic acid bacteria diversity in corn silage produced in Minas Gerais (Brazil)

The diversity of lactic acid bacteria (LAB) in silages produced in warm climate countries is not well known. This study aimed to identify and characterise the metabolic and genotypic aspects of autochthonous LAB isolated from corn silage produced in the state of Minas Gerais, Brazil. Eighty-eight LAB were isolated. To evaluate their performance at the strain level, all isolates were distinguished among strains using random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and repetitive extragenic palindromic PCR (REP-PCR) techniques. The organic acid and ethanol production were determined by high-performance liquid chromatography (HPLC). The fingerprints obtained by RAPD-PCR with a M13 primer were more discriminatory than those obtained with the REP-PCR technique using a (GACA)4 primer. Moreover, 28 representative isolates were identified as Lactobacillus acidophilus, L. buchneri, L. casei, L. diolivorans, L. hilgardii, L. paracasei, L. parafarraginis, L. plantarum, L. rhamnosus, L. zeae and Pediococcus acidilactici. Different fingerprinting profiles between isolates within the same species were observed. However, some strains isolated from different silages showed the same band profile, thus suggesting the presence of clusters with high similar fingerprints in silages from various regions. A variation in LAB diversity was observed in the silages of the evaluated regions, with L. rhamnosus and L. buchneri showing the highest distribution. Differences in organic acid production were observed among the strains belonging to the same species. This research contributes to a better understanding of the LAB community present in corn silage produced in warm climates. These strains will be studied as potential silage starters.     

Effects of Agave salmiana Otto Ex Salm-Dyck silage as forage on ruminal fermentation and growth in goats

Ensiling of Agave salmiana Otto Ex Salm-Dyck, a widespread plant in Mexico, as a viable preservation method to create a potential animal feed resource for ruminants was investigated. Fresh A. salmiana with 205 g dry matter (DM)/kg and wilted alfalfa with 602 g DM/kg were ensiled in combinations (DM:DM) of 1000:0, 500:500 and 350:650, to evaluate feeding value of agave:alfalfa silages on ruminal fermentation and growth of goats. Chemical composition and in situ ruminal disappearance of three total mixed rations (TMRs), which included 240 g/kg DM of each silage (1000:0, 500:500 and 350:650) were determined. The TMR were used to assess ruminal fermentation and growth of 15 goats (20 ± 2.2 kg body weight (BW)). Silage pH (≤4), lactate (>25 g/kg DM) and ammonia (<50 g/kg total N) concentrations indicate that silage quality was good. Lactic acid was the main acid in all silages, acetic acid concentrations were relatively low, and butyrate was only detected in only the 1000:0 agave:alfalfa silage. Potential DM disappearance of the TMR increased quadratically as the amount of alfalfa included in the silage mixture increased. The BW gain and feed efficiency were not changed by treatment, even though DM intake decreased and aNDF intake increased linearly as the amount of alfalfa included in the silage mixture increased. Ruminal pH and butyrate increased, and ammonia N, lactate and propionate decreased linearly as alfalfa proportion of alfalfa in the silage mixture was increased. The TMR ingredient selectivity by the goats may have limited goat performance when alfalfa was included in agave silage mixtures. Because the agave:alfalfa blend improved nutritional quality, ruminal digestibility and intake of agave silage, alfalfa inclusion may improve nutritional characteristics of agave plants silages for ruminants.     

Antibacterial activity of lactic acid bacteria included in inoculants for silage and in silages treated with these inoculants

AIMS: To determine antibacterial activity in lactic acid bacteria (LAB) silage inoculants and in wheat and corn silages which were treated with these inoculants. METHODS AND RESULTS: Wheat and two corn silages were prepared in 0.25 l sealed glass jars. Inoculant treatments were prepared for each type of silage with each of 10 LAB silage inoculants at inoculation rate of 10(6) CFU g(-1). Untreated silages served as controls. Antibacterial activity was determined in the inoculants and in their respective silages with Micrococcus luteus and Pseudomonas aeruginosa. Antibacterial activity was detected in nine of the 10 inoculants whereas such activity in the silages varied. Control silages did not have antibacterial activity. CONCLUSIONS: Many LAB silage inoculants have antibacterial activity and in some cases this activity is imparted on inoculated silages. SIGNIFICANCE AND IMPACT OF THE STUDY: This study was conducted as part of a broader research objective, which is to find out how LAB silage inoculants enhance ruminant performance. The results of this study indicate that LAB silage inoculants produce antibacterial activity, and therefore, have a potential to inhibit detrimental micro-organisms in the silage or in the rumen.