• Asian-Australasian Journal of Animal Sciences
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• v.8 no.6
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• pp.533-555
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• 1995

Direct-fed microbials (DFM) have been used to enhance milk production in lactating cattle and to increase feed efficiency and body weight gain in growing ruminants. Primary microorganisms that have been used as DFM for ruminants are fungal cultures including Aspergillus oryzae and Saccharomyces cerevisiae and lactic acid bacteria such as Lactobacillus or Streptococcus. Attempts have been made to determine the basic mechanisms describing beneficial effects of DFM supplements. Various modes of action for DFM have been suggested including : stimulation of ruminal microbial growth, stabilization of ruminal pH, changes in ruminal microbial fermentation pattern, increases in digestibility of nutrients ingested, greater nutrient flow to the small intestine, greater nutrient retention and alleviation of stress, however, these responses have not been observed consistently. Variations in microbial supplements, dosage level, production level and age of the animal, diet and environmental condition or various combinations of the above may partially explain the inconsistencies in response. This review summarizes production responses that have been observed under various conditions with supplemental DFM and also corresponding modification of ruminal fermentation and other changes in the gastrointestinal tract of ruminant animals.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.5
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• pp.722-730
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• 2016

The carcass traits and meat quality of Hanwoo (Korean native cattle) whose diets were supplemented with direct-fed microbial (DFM) and pine cone extract (PCE) were evaluated. Twenty head of Hanwoo steers were divided equally into four groups and for a period of 6 months were given different diets: One group was fed a basal diet as control (CON), the other three groups were fed a basal diet supplemented with DFM-1%, DFM+PCE-1% and DFM+PEC-3%, respectively. DFM+PCE3% diet resulted the lowest carcass quality grade. The loins of DFM-1% contained higher moisture and lower fat than did the loins from the CON group. The crude protein content of DFM+PCE-3% group was significantly higher than that of the other groups. The water holding capacity and Warner-Bratzler shear force of the DFM+PCE-1% and 3% groups were lower than those of the CON and DFM-1% groups. The DFM-1% and 3% groups contained lower saturated fatty acid, higher unsaturated fatty acid, mono-unsaturated fatty acid, and poly-unsaturated fatty acid than did CON and DFM+PCE 1% group. Moreover, the n6:n3 ratios of DFM-1% and DFM+PCE-1% and 3% groups were slightly lower than that of the CON group. Thus we concluded that DFM and PCE supplementation resulted healthier Hanwoo beef with lower fat content and n6:n3 ratio.

• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.269-277
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• 2022

Human activities account for approximately two-thirds of global methane emissions, wherein the livestock sector is the single massive methane emitter. Methane is a potent greenhouse gas of over 21 times the warming effect of carbon dioxide. In the rumen, methanogens produce methane as a by-product of anaerobic fermentation. Methane released from ruminants is considered as a loss of feed energy that could otherwise be used for productivity. Economic progress and growing population will inflate meat and milk product demands, causing elevated methane emissions from this sector. In this review, diverse approaches from feed manipulation to the supplementation of organic and inorganic feed additives and direct-fed microbial in mitigating enteric methane emissions from ruminant livestock are summarized. These approaches directly or indirectly alter the rumen microbial structure thereby reducing rumen methanogenesis. Though many inorganic feed additives have remarkably reduced methane emissions from ruminants, their usage as feed additives remains unappealing because of health and safety concerns. Hence, feed additives sourced from biological materials such as direct-fed microbials have emerged as a promising technique in mitigating enteric methane emissions.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.3
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• pp.370-374
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• 2005

Two experiments were conducted to evaluate the effects of direct-fed microbial supplementation on the growth performance and nutrient digestibility in pigs. In experiment 1, forty eight pigs were used in a 42-d growth assay. There were four pigs per pen and three pens per treatment. Dietary treatments included 1) NC (without antibiotic basal diet), 2) PC (NC diet+0.1% antibiotic, 100 g/kg chlortetracycline), 3) DFM-1 (NC diet+0.2% Lactobacillus reuteri and Lactobacillus salivarius complex) and 4) DFM-2 (NC diet+0.2% Lactobacillus reuteri, Lactobacillus salivarius, Lactobacillus plantarum and Yeast complex). For the overall period, no treatment had significant effects in growth performance. In the nutrition digestibility, the pigs fed DFM diets were improved in DM and N digestibility compared with the pigs fed NC and PC diets but it was not significantly different. In experiment 2, sixty four crossbred pigs were used in a 98-d growth assay. There were four pigs per pen and four pens per treatment. Dietary treatments included 1) HND (high nutrient diet), 2) LND (low nutrient diet), 3) HND+DFM (HND diet+0.2% Lactobacillus reuteri and Lactobacillus plantarum complex) and 4) LND+DFM (LND diet+0.2% Lactobacillus reuteri and Lactobacillus plantarum complex). For overall period of growing phase, the pigs fed LND diets had improved gain/feed (p=0.01) and for overall period in the finishing phase, the pigs fed LND with DFM diets had higher ADG, ADFI and gain/feed than the others but there were no significant differences (p>0.13). In total period of growing-finishing phase, the pigs fed LND diet had higher gain/feed than the pigs fed HND diets (p<0.05). In growing phase, there were not significant differences among the treatments means for DM and N digestibility. However, the pigs fed diets with DFM had improved N digestibility (p<0.02) compared to the pigs fed diets without DFM in finishing phase. In conclusion, DFM slightly improved the growth performance in growing-finishing pigs.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.5
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• pp.643-649
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• 2011

The objective of this study was to determine the effect of feeding direct-fed microbials (DFM) on the growth performance and prophylaxis of calf diarrhea during the pre-weaning period as an alternative to antibiotics. A multi-species DFM was formulated including three lactic acid bacteria (Lactobacillus salivarius Ls29, Pediococcus acidilactia Pa175, and L. plantarum Lp177), three Bacillus strains (B. subtilis T4, B. polymyxa T1 and SM2), one yeast, Saccharomyces boulardii, and a nonpathogenic E. coli Nissle 1917. Lactic acid bacteria and Bacillus strains were selected based on the antibacterial activity against various animal pathogens, especially pathogenic E. coli using agar diffusion methods in vitro. Test and control groups were fed milk replacer and calf starter supplemented with DFM ($10^9$ cfu each of eight species/d/head, n = 29) or with antibiotics (0.1% neomycin sulfate in milk replacer and Colistin 0.08% and Oxyneo 110/110 0.1% in calf starter, n = 15), respectively. Overall fecal score and the incidence rate of diarrhea were reduced in the DFM group compared to the antibiotics one. About 40% of calves in antibiotic group suffered from diarrhea while in DFM group only 14% showed diarrhea. There was no difference in the average daily gain and feed efficiency of two groups. The hematological levels of calves were all within the normal range with no significant difference. In conclusion, the feeding of multispecies DFM during the pre-weaning period could reduce calf diarrhea and there was no difference in the growth performance between the groups, thus showing the potential as an alternative to antibiotics.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1411-1416
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• 2004

The objective of this work was to isolate a microorganism, able to produce high lactate dehydrogenase (LDH) activity, for use as a microbial feed additive. The LDH is an important enzyme for lactate conversion in the rumen, thereby possibly overcoming lactic acidosis owing to sudden increases of cereal in the diets of ruminants. In the present study, various bacterial strains were screened from a variety of environments. Among the isolated microorganisms, strain FFy 111-1 isolated from a Korean traditional fermented vegetable food called Kimchi showed the highest enzyme activity, along with retaining strong enzyme activity even in rumen fluid in vitro. Based on morphological and biochemical characteristics as well as compositions of cellular fatty acids plus API analyses, this strain was identified as Lactobacillus sp. The optimum temperature and pH for growth were found to be 30$^{\circ}C$ and pH 6.5, respectively. A maximum cell growth of 2.2 at $A_{650}$ together with LDH activity of 2.08 U per mL was achieved after 24 h of incubation. Initial characterization of FFy 111-1 suggested that it could be a potential candidate for use as a direct-fed microbial in the ruminant animals.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.162-165
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• 2002

With the objective of identifying the commercial potential of new direct-fed microbials, several temperature-tolerant strains were isolated from cane molasses at $39^{\circ}C$ and tested for their tolerance to pH, bile salts, and a mixture of volatile fatty acids (acetic acid:propionic acid:butyric acid=6.5:2.0:1.5). It was found that the isolated strain DY 252 grew very well up to pH 2.0 and was resistant to relatively high concentrations of bile salts. Among the strains tested, DY 252 was least inhibited by the addition of volatile fatty acids to the growth medium at $39^{\circ}C$. Accordingly, it would appear that strain DY 252, identified as yeast Issatchenkia orientalis, may be a potential candidate for use as a microbial feed additive.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.863-876
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• 2019

Farm animals such as piglets are often affected by environmental stress, which can disturb the gut ecosystem. Antibiotics were commonly used to prevent diarrhea in weaned piglets, but this was banned by the European Union due to the development of antibiotic resistance. However, the use of probiotics instead of antibiotics may reduce the risk posed by pathogenic microorganisms and reduce the incidence of gastrointestinal diseases. Therefore, this study was conducted to investigate the effects of Lactobacillus casei Zhang on the mechanical barrier and immune function of early-weaned piglets infected using Escherichia coli K88 based on histomorphology and immunology. Fourteen-day-old weaned piglets were divided into a control group and experimental groups that were fed L. casei Zhang and infected with E. coli K88 with or without prefeeding and/or postfeeding of L. casei Zhang. The L. casei Zhang dose used was $10^7CFU/g$ diet. Jejunum segments were obtained before histological, immunohistochemical, and western blot analyses were performed. In addition, the relative mRNA expression of toll receptors and cytokines was measured. Piglets fed L. casei Zhang showed significantly increased jejunum villus height, villus height-crypt depth ratio, muscle thickness, and expression of proliferating cell nuclear antigen and tight junction proteins ZO-1 and occludin. The use of L. casei Zhang effectively reduced intestinal inflammation after infection. We found that L. casei Zhang feeding prevented the jejunum damage induced by E. coli K88, suggesting that it may be a potential alternative to antibiotics for preventing diarrhea in early-weaned piglets.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.239-246
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• 2015

The present study was conducted to evaluate the effect of the dietary supplementation of Bacillus amyloliquefaciens-based direct-fed microbial (DFM) on growth performance, nutrient utilization, intestinal morphology and cecal microflora in broiler chickens. A total of two hundred and eighty eight 1-d-old Arbor Acres male broilers were randomly allocated to one of four experimental treatments in a completely randomized design. Each treatment was fed to eight replicate cages, with nine birds per cage. Dietary treatments were composed of an antibiotic-free basal diet (control), and the basal diet supplemented with either 15 mg/kg of virginiamycin as antibiotic growth promoter (AGP), 30 mg/kg of Bacillus amyloliquefaciens-based DFM (DFM 30) or 60 mg/kg of Bacillus amyloliquefaciens-based DFM (DFM 60). Experimental diets were fed in two phases: starter (d 1 to 21) and finisher (d 22 to 42). Growth performance, nutrient utilization, morphological parameters of the small intestine and cecal microbial populations were measured at the end of the starter (d 21) and finisher (d 42) phases. During the starter phase, DFM and virginiamycin supplementation improved the feed conversion ratio (FCR; p<0.01) compared with the control group. For the finisher phase and the overall experiment (d 1 to 42) broilers fed diets with the DFM had better body weight gain (BWG) and FCR than that of control (p<0.05). Supplementation of virginiamycin and DFM significantly increased the total tract apparent digestibility of crude protein (CP), dry matter (DM) and gross energy during both starter and finisher phases (p<0.05) compared with the control group. On d 21, villus height, crypt depth and villus height to crypt depth ratio of duodenum, jejunum, and ileum were significantly increased for the birds fed with the DFM diets as compared with the control group (p<0.05). The DFM 30, DFM 60, and AGP groups decreased the Escherichia coli population in cecum at d 21 and d 42 compared with control group (p<0.01). In addition, the population of Lactobacillus was increased in DFM 30 and DFM 60 groups as compared with control and AGP groups (p<0.01). It can be concluded that Bacillus amyloliquefaciens-based DFM could be an alternative to the use of AGPs in broilers diets based on plant protein.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.387-393
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• 2016

This study was conducted to determine the fermentative characteristics of wheat bran inoculated with a starter culture of direct-fed microbes as a microbial wheat bran (DMWB) feed additive. Wheat bran was prepared with 1% (w/w, 0.5% Lactobacillus plantarum and 0.5% of Saccharomyces cerevisiae) starter culture treatment (TW) or without starter culture as a control (CW). Those were fermented under anaerobic conditions at $30^{\circ}C$ incubation for 3 days. Samples were taken at 0, 1, 2, and 3 days to analyze chemical composition, microbial growth, pH, and organic acid content. Chemical composition was not significantly different between CW and TW (p > 0.05). In TW, the number of lactic acid bacteria and yeast increased during the 3 days of fermentation (p < 0.05) and the population of lactic acid bacteria was significantly higher than in CW (p < 0.05). After 3 days, the number of yeast in TW was $7.50{\pm}0.07log\;CFU/g$, however, no yeast was detected in CW (p < 0.05). The pH values of both wheat bran samples decreased during the 3 days of fermentation (p < 0.05), and TW showed significantly lower pH than CW after 3 days of fermentation (p < 0.05). Contents of lactic acid and acetic acid increased significantly at 3rd day of fermentation in TW. However, no organic acids were generated in CW during testing period. These results suggest that 3 days of fermentation at $37^{\circ}C$ incubation after the inoculation wheat bran with starter culture makes it possible to produce a direct-feed with a high population of lactic acid bacteria at more than $10^{11}CFU/g$.