The ruminant gut microbiome vs enteric methane emission: The essential microbes may help to mitigate the global methane crisis

Ruminants release enteric methane into the atmosphere, significantly increasing greenhouse gas emissions and degrading the environment. A common focus of traditional mitigation efforts is on dietary management and manipulation, which may have limits in sustainability and efficacy, exploring the potential of essential microorganisms as a novel way to reduce intestinal methane emissions in ruminants; a topic that has garnered increased attention in recent years. Fermentation and feed digestion are significantly aided by essential microbes found in the rumen, such as bacteria, fungi, and archaea. The practical implications of the findings reported in various studies conducted on rumen gut concerning methane emissions may pave the way to understanding the mechanisms of CH4 production in the rumen to enhance cattle feed efficiency and mitigate CH4 emissions from livestock. This review discussed using essential bacteria to reduce intestinal methane emissions in ruminants. It investigates how particular microbial strains or consortia can alter rumen fermentation pathways to lower methane output while preserving the health and productivity of animals. We also describe the role of probiotics and prebiotics in managing methane emissions using microbial feed additives. Further, recent studies involving microbial interventions have been discussed. The use of new methods involving functional metagenomics and meta-transcriptomics for exploring the rumen microbiome structure has been highlighted. This review also emphasizes the challenges faced in altering the gut microbiome and future directions in this area.

Effects of Chitosan-Based Additive on Rumen Fermentation and Microbial Community, Nutrients Digestibility and Lactation Performance in Goats

Recently, the potential of using chitosan (CHI) as a feed additive to enhance ruminal fermentation and improve animal performance has gained increasing attention in ruminant nutrition. This study was undertaken to investigate the effect of dietary supplementation with increasing doses of CHI on rumen fermentation attributes and microbial composition, digestibility and milk performance in Dhofari goats. Twenty-four lactating goats (27 ± 1.8 kg of initial live body weight) were fed a control diet comprising of Rhodes grass hay plus a concentrate feed mixture. Goats were assigned to one of three experimental treatments (n = 8 per treatment) as: (1) control diet with no supplement (CTRL), (2) control diet with 0.300 g/day CHI (CHI0.3) and (3) control diet supplemented with 0.600 g/day CHI (CHI0.6) for a 45-day experimental period. Dietary supplementation with increasing doses of CHI decreased (p < 0.05) linearly ruminal pH (p = 0.023), total short chain fatty acids concentrations (p = 0.011), acetate (p = 0.013) and butyrate (p = 0.042) proportions, acetate to propionate ratio (p < 0.001), estimated methane (CH4) production (p < 0.001), ammonia nitrogen concentrations (p = 0.003) and protozoa abundance (p = 0.003). However, the ruminal propionate proportion augmented (p = 0.002) linearly with increasing doses of CHI in the diet. Increasing doses of CHI linearly increased the abundance of the ruminal propionate-producing bacteria, while diminished acetate and CH4-producing bacteria (p < 0.05). Serum total protein (p = 0.037) and glucose (p = 0.042) levels linearly increased as CHI doses increased in the diet. However, serum UREA levels decreased linearly (p = 0.002) by 21% with increasing CHI amounts in the diet. The digestibility of organic matter, crude protein and neutral detergent fibre increased linearly with the increasing CHI doses (p < 0.05). Neither linear nor quadratic responses (p > 0.05) were observed in daily milk yield and feed efficiency by supplementing the diet with CHI. In conclusion, supplementing the diet with CHI at a dose of 0.600 g/day as a feed additive for dairy goats reduced estimated CH4 generation and improved fibre and protein digestion, with no influence on feed intake, milk yield or composition.

The effect of silkworms (Bombyx mori) chitosan on rumen fermentation, methanogenesis, and microbial population in vitro

Background and Aim

Ruminant enteric methane (CH4) is one of the largest sources of greenhouse gases that contribute to global warming. To minimize environmental harm caused by ruminants' CH4 production, natural substances can be used to suppress it. Chitosan from crustacean sources had been known to obstruct CH4 generation in the rumen. About 18% of silkworm pupae is chitin, but little is known about the impact of silkworm pupae chitosan on rumen methanogenesis. This study investigated the efficacy of the silkworm chitosan extraction method and its impact on rumen fermentation, methanogenesis, and microbial growth in vitro.

Materials and Methods

This study employed a randomized complete block design featuring five treatments and four batches for rumen incubation as the blocking factor. In this study, five treatments were implemented: Control (CO) (basal diet with no added chitosan), basal diet with 6% chitosan from the Chinese Silkworm strain 804 (CHI804), basal diet with 6% chitosan from the PS 01 Hybrid Silkworm strain (CHIPS01), basal diet with 6% chitosan from the Hybrid F1 Japanese 102 × Chinese 202 races (CHIJC02), and basal diet with 6% commercial shrimp shell chitosan as the positive control (CHICOMM). The in vitro experiments assessed digestibility, pH, total gas generation, CH4 production, ammonia nitrogen (NH3-N), and short-chain fatty acid levels, along with microbial population. Data were analyzed using a general linear model followed by Duncan's test when applicable.

Results

A significant effect on dry matter digestibility (DMD), total gas production, CH4, NH3-N, and rumen microbial populations (Methanogens, Ruminoccocus albus, Ruminoccocus flavefaciens, Selonomonas ruminantium, Butyrivibrio fibrisolvens, Streptoccocus bovis, Prevotella spp., and Bacteroides spp.) was observed (p < 0.05). The extracted chitosan (CHIJC02) used in this study exhibited a similar quality to that of commercial chitosan (CHICOMM). CHI804 treatment could reduce gas production, NH3-N production, and B. fibrisolvens population significantly (p < 0.05), while CHIJC02 could reduce CH4 production, methanogen population, acetate (C2) production, and increase propionate (C3) production significantly (p < 0.05). CHIJC02 and CHICOMM treatments could also increase the population of R. flavefaciens, S. ruminantium, and Bacteroides spp. significantly (p < 0.05). Chitosan addition significantly (p < 0.05) reduced DMD but did not impact organic matter digestibility or pH.

Conclusion

The extracted chitosan mimics commercial chitosan in physico-chemical properties. Chitosan derived from Japanese and Chinese F1 hybrid silkworm strains demonstrated superior capacity for inhibiting CH4 generation compared to commercial chitosan. The quality and effects on methanogenesis, rumen fermentation, and rumen microbial populations can differ depending on the origin of chitosan.

In Vitro Evaluation of Chito-Oligosaccharides on Disappearance Rate of Nutrients, Rumen Fermentation Parameters, and Micro-Flora of Beef Cattle

The study aimed to investigate the effect of dietary chitosan oligosaccharides (COS) meal levels on the nutrient disappearance rate, rumen fermentation, and microflora of beef cattle in vitro. A total of 24 fermentation tanks were randomly divided into four treatments containing 0% COS (CON), 0.02% COS, 0.04% COS, and 0.08% COS for an 8-day experiment period, with each treatment comprising six replicates. The disappear rates of DM, CP, EE, and total gas production were quadratically increased with increasing COS levels. The disappear rates of DM, CP, EE, and ADF were greatest, whereas the total gas production was lowest in the 0.08% COS group. The pH, NH3-N, MCP, the content of propionate, isobutyrate, butyrate, valerate, and the A/P were quadratically increased with increasing COS levels, while the A/P were linearly decreased. The pH, MCP, and the content of propionate, and butyrate were highest, whereas the NH3-N and the content of acetate, isobutyrate, valerate, and the A/P were lowest in the 0.08% COS group. Microbiomics analysis showed that the rumen microbial diversity was not altered between the CON and the 0.08% COS group. However, the relative abundance of Methanosphaera, Ruminococcus, Endomicrobium, and Eubacterium groups was increased, and the relative abundance of pathogenic bacteria Dorea and Escherichia-Shigella showed a decrease in the 0.08% COS group. Overall, the 0.08% COS was the most effective among the three addition levels, resulting in an increase in the disappearance rate of in vitro fermented nutrients and improvements in rumen fermentation indexes and microbial communities. This, in turn, led to the maintenance of rumen health.

Enhancing quality of ruminant feed through fungal treatment: Usage of bamboo shoot residues

In this investigation, we explore the harnessing of bamboo shoot residues (BSR) as a viable source for ruminant feed through fungal treatment, with the overarching objective of elevating feed quality and optimizing bamboo shoot utilization. The white-rot fungi (Wr.fungi), Aspergillus niger (A.niger), and its co-cultures (A.niger&Wr.fungi) were employed to ferment BSR. And the impact of different fermentation methods and culture time on the chemical composition (Crude protein Ash, neutral detergent fibre and acid detergent fibers), enzyme activity (Cellulase, Laccase, Filter paperase and Lignin peroxidase activities), and rumen digestibility in vitro were assessed. The findings reveal a nota ble 30.39% increase in crude protein in fermented BSR, accompanied by respective decreases of 13.02% and 17.31% in acid detergent fiber and neutral detergent fibre content. Enzyme activities experienced augmentation post-fermentation with A.niger&Wr.fungi. Specifically, the peak Cellulase, Laccase, and Lignin peroxidase activities for BSR with Wr.fungi treatment reached 748.4 U/g, 156.92 U/g, and 291.61 U/g, respectively, on the sixth day of fermentation. Concurrently, NH3-N concentration exhibited an upward trend with prolonged fermentation time. Total volatile fatty acids registered a decline, and the Acetate/Propionate ratio reached its nadir after 6 days of fermentation under the A.niger&Wr.fungi treatment. These outcomes furnish a theoretical foundation for the development of ruminant feeds treated via fungal co-culture.

Use of irradiated chitosan as a matrix for slow-release urea and in vitro fermentation characteristics of slow-release urea supplementation in ruminant rations

Background and Aim

Irradiated chitosan can be used as a matrix for slow-release urea (SRU) production. This study aimed to (1) determine the optimal formulation of irradiated chitosan matrix for controlling nitrogen release and (2) evaluate the characteristics of SRU in vitro fermentation based on irradiated chitosan as a feed supplement.

Materials and Methods

In the first phase of the investigation, four chitosan-based SRU formulations with varying amounts of acrylamide (3 and 5 g) and gamma irradiation (5 and 10 kGy) were evaluated. Scanning electron microscopy, Fourier transform mid-infrared spectroscopy, and ammonia release characteristics were used to observe morphological, functional group, and ammonia release characteristics. In the second phase of research, the most effective SRU formulation was utilized as a supplement to ruminant rations based on rice straw, sorghum straw, and alfalfa. Gas production, rumen fermentation characteristics, and methane gas production were observed in vitro.

Results

On the basis of surface image analysis, the four SRU formulas generate a similar appearance. Compared with untreated urea, the SRU3 formula reduced the percentage of ammonia emission by 12.85%-27.64% after 24 h of incubation (p = 0.05), as determined by the first phase study. SRU3 became the basis for the second testing phase. The addition of SRU3 did not affect the optimal gas production in vitro. SRU3 treatment produced less gas than Optigen® treatment (p = 0.05). With regard to rumen fermentation and digestibility, Optigen® yielded better results than SRU3 (p = 0.05). However, the treatment with SRU3 resulted in reduced methane production compared to that in the control (p = 0.05).

Conclusion

Irradiated chitosan as an SRU matrix may control the release of ammonia in the rumen medium. The SRU3 formulation is the most effective. The addition of SRU to rice straw-based rations reduces methane production without affecting in vitro digestibility.

Effect of Chitosan on Ruminal Fermentation and Microbial Communities, Methane Emissions, and Productive Performance of Dairy Cattle

This study aimed to expand the knowledge about the activity and mode of action of CHI on methanogenesis and rumen microbial populations in vivo. A total of 16 lactating dairy cows were distributed in two groups, one of them receiving 135 mg CHI/kg body weight daily. The effect on productive performance, milk composition, fermentation efficiency, methane emissions, microbial protein synthesis, and ruminal microbial communities was determined. Supplementation with CHI did not affect rumen microbial diversity but increased the relative abundance (RA) of the bacteria Anaeroplasma and decreased those of rumen ciliates and protozoa resulting in a shift towards a lower acetic to propionic ratio. However, no effect on milk yield or methane intensity was observed. In conclusion, supplementing 135 mg CHI/kg body weight increased the RA of Anaeroplasma and decreased those of rumen ciliates and protozoa, both being related to fiber degradation in the rumen in different ways and resulted in a shift of ruminal fermentation towards more propionate proportions, without affecting CH4 emissions, milk yield, or milk composition. Further research with higher doses would be necessary to assess the potential use of this additive as a methane inhibitor.

Role of Chitin and Chitosan in Ruminant Diets and Their Impact on Digestibility, Microbiota and Performance of Ruminants

The slow progress in the development of the subsector, particularly of alternative feed sources such as agro-industrial byproducts and unconventional feed resources, has deepened the gap in the availability of and accessibility to animal feed. Production of animal feed is highly resource demanding. Recently, it has been shown that increasing climate change, land degradation, and the recurrence of droughts have worsened the feed gap. In the backdrop of these challenges, there has been attention to food-not-feed components, which have great potential to substitute human-edible components in livestock feeding. Chitosan, a non-toxic polyglucosamine, is widely distributed in nature and used as a feed additive. Chitosan is obtained from the de-acetylation process of the chitin and is mostly present in shrimp, crabs, and insect exoskeletons, and has antimicrobial and anti-inflammatory, anti-oxidative, antitumor, and immune-stimulatory hypo-cholesterolemic properties. This review article discusses the results of recent studies focusing on the effects of chitosan and chitin on the performance of dairy cows, beef steers, sheep, and goats. In addition, the effects of chitosan and chitin on feed intake, feed digestibility, rumen fermentation, and microbiota are also discussed. Available evidence suggests that chitosan and chitin used as a feed additive for ruminants including dairy cows, beef steers, sheep, goats, and yaks have useful biological effects, including immune-modulatory, antimicrobial, and other important properties. These properties of chitosan and chitin are different from the other feed additives and have a positive impact on production performance, feed digestibility, rumen fermentation, and bacterial population in dairy cows, beef steers, sheep, goats, and yaks. There is promising evidence that chitosan and chitin can be used as additives in livestock feed and that well-designed feeding interventions focusing on these compounds in ruminants are highly encouraged.

Chitosan/Calcium-Alginate Encapsulated Flaxseed Oil on Dairy Cattle Diet: In Vitro Fermentation and Fatty Acid Biohydrogenation

The aim of this study was to investigate the effect of using chitosan nanoparticles and calcium alginate in the encapsulation of flaxseed oil on the biohydrogenation of unsaturated fatty acids and in vitro fermentation. The experiments were performed in a completely randomized design with 7 treatments. The experimental treatments included: diets without oil additive (control), diet containing 7% flaxseed oil, diet containing 14% flaxseed oil, diet containing 7% oil encapsulated with 500 ppm chitosan nanocapsules, diet containing 14% flaxseed oil encapsulated with 1000 ppm chitosan nanocapsules, diet containing 7% of flaxseed oil encapsulated with 500 ppm of calcium alginate nanocapsules, diet containing 14% flaxseed oil encapsulated with 1000 ppm calcium alginate nanocapsules. The results showed that encapsulation of flaxseed oil with calcium alginate (14%) had a significant effect on gas production (p < 0.05). The treatment containing calcium alginate (14%) increased the digestibility of dry matter compared to the control treatment, but the treatments containing chitosan caused a significant reduction (p < 0.05). The results indicated that the percentage of ruminal saturated fatty acids decreased by encapsulation of flaxseed oil with chitosan (14% and 7%). The percentage of oleic unsaturated fatty acid by encapsulating flaxseed oil with chitosan (14%) had a significant increase compared to the control treatment (p < 0.05). As a result, encapsulating flaxseed oil with chitosan (14%) reduced the unsaturated fatty acids generated during ruminal biohydrogenation.

Meta-analysis of dietary chitosan effects on performance, nutrient utilization, and product characteristics of ruminants

Chitosan (CHI) has been used as a feed additive in ruminant diets, but the effects obtained to date have been varied. This study aimed to evaluate the dietary addition of CHI on performance, nutrient utilization, and product characteristics of ruminants by using a meta-analysis approach. A total of 15 articles that composed of 21 studies and 57 data points were included in the database. Number of articles reported the effects of dietary CHI addition were six on beef cattle, seven on dairy cows, and two papers on sheep. Data analysis was based on the mixed model methodology, in which CHI addition levels were considered as fixed effects whereas different studies were treated as random effects. Results revealed that, across various studies, CHI decreased ruminal acetate proportion (p < 0.05) and increased propionate proportion (p < 0.01). Dry matter and crude protein digestibility were elevated due to CHI addition (p < 0.05). CHI decreased blood cholesterol level (p < 0.05) and increased monounsaturated fatty acid proportion in the milk (p < 0.05). However, CHI addition had no effect on dry matter intake, milk production, and milk efficiency of ruminants. In conclusion, CHI is able to modify rumen fermentation towards a favorable direction, but it limitedly affects performance of ruminants.

Degradability, in vitro fermentation parameters, and kinetic degradation of diets with increasing levels of forage and chitosan

Chitosan is the second most important natural biopolymer in the world, extracted from crustaceans, shrimps, and crabs and can modulate rumen fermentation. Our hypothesis is that the addition of chitosan alters the fermentation patterns of different diets for ruminants. This study aimed to evaluate the effects of different levels of chitosan and forage on in vitro dry degradation kinetics and fermentation in a gas production system. The chitosan levels (0, 1625, 3,500, or 7,500 mg/kg of dry matter [DM]) were arranged in a completely randomized block design, and for in vitro ruminal fermentation assay, we used a split splot arrangement. Into the incubator, all chitosan levels were distributed in the four jars, and the forage levels varying on 100, 65, 50, 35, and 20 on DM basis. There was an interaction effect for chitosan and forage levels (P ≤ 0.05) on IVDMD; IVOMD. IVDCP and IVDNDF. Chitosan negatively affected IVDMD in all roughage levels evaluated. The pH and ammonia concentration present effect only for roughage levels and incubation hours. The chitosan did not change (P = 0.3631) the total short-chain fatty acid concentration (overall mean = 21.19 mmol/L) and the C2:C3 ratio (overall mean = 5.85). The IVDCP showed the same decreasing quadratic behavior (P < 0.0001). The increasing chitosan addition increases (P < 0.0001) the gas production and decreases (P < 0.0001) the lag time (parameter C) of diets with greater concentrate participation, characterizing greater efficiency in the degradability of the diet, confirming its potential use in diets for ruminants. Chitosan changes in vitro dry degradation kinetics and fermentation at the minimum dose of 1,722 mg/kg DM for all diets. The roughage level influenced the in vitro nutrients degradability and cumulative gas production.

Effect of increasing doses of chitosan to grazing beef steers on the relative population and transcript abundance of Archaea and cellulolytic and amylolytic bacterias

This paper aims to investigate the influence of increasing chitosan doses on the relative proportion and abundance of cellulotytic, amylolytic bacteria, and Archaea transcripts for grazing cattle. Five rumen cannulated crossbread steers [3.6 months and 300 ± 25 kg body LW (live weight), mean ± standard deviation] were used in a 5 × 5 latin square design, randomly assigned to treatment sequence containing chitosan added to 0, 400, 800, 1200, or 1600 mg/kg concentrate. There was the effect of chitosan on the population of Fibrobacter succinogenes, Ruminococcus albus, and Archaea. The lowest population of these bacteria of 576.60 mg/kg DM (dry matter), 1010.40 mg/kg DM, and 634.80 mg/kg DM were noted when chitosan was added at levels of 3.87, 4.16, and 3.52. Except for Ruminococcus albus, which was not affected by increasing chitosan doses, supplementation of this additive in the concentrate quadratically increased the relative abundance of Fibrobacter succinogenes and Archaea Supplemental 740 mg CHI/kg concentrate for grazing steers receiving concentrate at 150 grams/100 kg LW is recommended to promote minimal effect on the relative population and abundance of cellulolytics and amylomatics and to restrict Archaea growth.

Effects of mannan oligosaccharides on growth performance, nutrient digestibility, ruminal fermentation and hematological parameters in sheep

Background

Mannan oligosaccharides (MOS) are a promising feed additive in animal husbandry due to mainly improving animal health status. The purpose of this study was to investigate the effects of MOS on growth performance, nutrient digestibility, ruminal fermentation, and twelve hematological parameters in sheep.

Methods

Ninety-six healthy Hu rams with similar body weights were chosen and divided into four treatment groups (twenty-four rams in each group), in which four different doses of MOS were tested: 0%, 0.8%, 1.6% and 2.4% of the basal diet (on an as-fed basis).

Results

The results showed that supplementation dietary MOS did not affect feed intake, body weight, average daily weight gain, or ruminal short-chain fatty acids (SCFAs) concentration; the ratio of individual fatty acids to total SCFAs, the C2/C3 ratio, and the hematological parameters in the sheep were also unaltered (P > 0.05). Conversely, supplementation dietary MOS increased the dry matter, organic matter, crude protein, neutral detergent fiber, acid detergent fiber, and ash apparent digestibility (P < 0.05), and decreased the ruminal ammonia concentration in the sheep (P < 0.05), especially at a dose of 1.6%.

Conclusions

This indicates that supplementation dietary MOS improved nutrient utilization by the sheep and nitrogen metabolism in the rumen; however, the effects are too slight to interfere with the basal metabolism in the sheep.

Effect of Chitosan and Naringin on Enteric Methane Emissions in Crossbred Heifers Fed Tropical Grass

Simple Summary

The increase in human population and the concomitant rise in demand for animal protein have contributed to augment enteric methane emissions. It is imperative to reduce methane, increase sustainable production, avoid the use of chemical compounds, and guarantee quality products for the consumer. Chitosan and naringin possess antimicrobial properties, and they have shown their capacity to reduce methane in in vitro trials. This study investigated their effects as feed additives given to improve ruminal fermentation and nutrient utilization and decrease methane in crossbred heifers fed tropical grass. In in vitro experiments, chitosan and naringin at three levels (0, 1.5, 3.0 g/kg) showed significant methane reductions when 1.5 g/kg of chitosan was included. The in situ study did not reveal changes in rumen degradability with the inclusion of the additives. However, in in vivo assays, chitosan and naringin at 1.5 or 3.0 g/kg dry matter intake or the combination of both compounds (1.5 and 1.5 g/kg) given directly into the rumen did not induce changes in rumen fermentation, methane production, or nutrient utilization. However, given the promising evidence from other studies, more research needs to be conducted to clarify the potential effects of chitosan and naringin in animal production.

Abstract

In order to meet consumer needs, the livestock industry is increasingly seeking natural feed additives with the ability to improve the efficiency of nutrient utilization, alternatives to antibiotics, and mitigate methane emissions in ruminants. Chitosan (CHI) is a polysaccharide with antimicrobial capability against protozoa and Gram-positive and -negative bacteria, fungi, and yeasts while naringin (NA) is a flavonoid with antimicrobial and antioxidant properties. First, an in vitro gas production experiment was performed adding 0, 1.5, 3.0 g/kg of CHI and NA under a completely randomized design. The substrate containing forage and concentrate in a 70:30 ratio on a dry matter (DM) basis. Compounds increased the concentration of propionic acid, and a significant reduction in methane production was observed with the inclusion of CHI at 1.5 g/kg in in vitro experiments (p < 0.001). In a dry matter rumen degradability study for 96 h, there were no differences in potential and effective degradability. In the in vivo study, six crossbred heifers fitted with rumen cannulas were assigned to a 6 × 6 Latin square design according to the following treatments: control (CTL), no additive; chitosan (CHI1, 1.5 g/kg DMI); (CHI2, 3.0 g/kg DMI); naringin (NA1, 1.5 g/kg DMI); (NA2, 3.0 g/kg DMI) and a mixture of CHI and NA (1.5 + 1.5 g/kg DMI) given directly through the rumen cannula. Additives did not affect rumen fermentation (p > 0.05), DM intake and digestibility of (p > 0.05), and enteric methane emissions (p > 0.05). CHI at a concentration of 1.5 g/kg DM in in vitro experiments had a positive effect on fermentation pattern increasing propionate and reduced methane production. In contrast, in the in vivo studies, there was not a positive effect on rumen fermentation, nor in enteric methane production in crossbred heifers fed a basal ration of tropical grass.

Influence of chitosan sources on intake, digestibility, rumen fermentation, and milk production in tropical lactating dairy cows

The aim of study was to compare the influence of chitosan sources (commercial chitosan vs chitosan extract) on rumen fermentation, methane (CH₄) emission, and milk production in tropical lactating dairy cows. Six lactating Holstein-Friesian crossbreeds (410 ± 5 kg, 120 ± 21 day-in-milk) were arranged in a 3 × 3 replicated Latin square design. In addition to control, a 2% chitosan extract supplement and a 2% commercial chitosan supplement of dry matter intake were the treatments. The results denoted that no significant differences on daily dry matter, nutrients, or estimated energy intake were noted when cows received different sources of chitosan. Nutrient digestibility was not influenced differently by extraction-based or commercial chitosan supplements. The pH, temperature, ammonia nitrogen, blood urea, and microbial count were similar among treatments. The different sources of chitosan supplements did not change the totals of volatile fatty acids, acetate, and butyrate; in contrast, different chitosan sources influenced (P<0.05) propionate content. The ruminal acetate to propionate ratio was markedly (P<0.05) reduced with chitosan supplement, but no change appeared between sources of chitosan. At 4 h after feeding, the methane estimation significantly decreased with the addition of chitosan supplementation (P<0.05) compared to the control group. The purine derivatives and microbial protein synthesis were not altered by the treatments. No significant differences existed on milk yield, milk composition, or milk urea nitrogen when cows received different sources of chitosan (P>0.05). In summary, supplementing extracted chitosan showed more potential than did the commercial chitosan for enhancing economic efficiency and recycling shrimp residues, therefore, reducing environmental waste.

Effect of Chitosan Inclusion and Dietary Crude Protein Level on Nutrient Intake and Digestibility, Ruminal Fermentation, and N Excretion in Beef Heifers Offered a Grass Silage Based Diet

Nitrogen (N) use efficiency in beef cattle is low (10-20%), resulting in large amounts of N excreted into the environment. The objective of this study was to evaluate the effects of chitosan inclusion and dietary crude protein (CP) level on nutrient intake and digestibility, ruminal fermentation, and N excretion in beef heifers. Eight Belgian Blue × Holstein Friesian cross beef heifers (752 ± 52 kg BW) were used in a 4 × 4 Latin square with a 2 × 2 factorial design. Factors were dietary CP concentration-high CP, 16% (HP) or low CP, 12% (LP)-and chitosan inclusion-0 or 10 g kg^-1 dry matter (DM) offered at 50:50 forage concentrate ratio on a dry matter (DM) basis. Apparent total tract digestibility of DM, organic matter (OM), and CP were reduced (p < 0.001) with chitosan inclusion, whereas offering the HP diets increased apparent total tract digestibility of CP (p < 0.001). Offering the HP diets increased urinary N excretion (p < 0.001), while chitosan inclusion increased N excretion in faeces (p < 0.05). Ruminal pH was increased with chitosan inclusion (p < 0.01). There was a CP × chitosan interaction for rumen ammonia (NH₃) concentrations (p < 0.05). Including chitosan in the HP diets increased ruminal NH₃ concentration while having no effect on the LP diets. Urinary N excretion was increased with increased levels of CP, but chitosan inclusion increased the quantity of N excreted in the faeces.

Chitosan and cottonseed processing method association on carcass traits and meat quality of feedlot lambs

The objective of this study was to evaluate the effects of the association of cottonseed processing method with chitosan on carcass traits and meat quality of lambs finished in feedlot. Eighty lambs with an average body weight of 20.6 kg, with 04 months of age, were distributed in a completely randomized design, in a 2 x 2 factorial arrangement. The factors were represented by two cottonseed processing method (whole or ground) and two levels of chitosan (0 and 136 mg/kg BW). The association of cottonseed processing method with chitosan in the lamb diet did not affect (P>0.05) carcasses traits. The pH, color, cooking losses, shear force, and proximate composition of meat were also not affected (P>0.05) by the processing method of cottonseed or its association with chitosan in the lamb diets. There was an increase in palmitoleic (c9-C16:1; P = 0.01) and conjugated linoleic (P = 0.02) fatty acids when ground cottonseed was associated with chitosan. Ground cottonseed associated with chitosan increases the concentration of unsaturated fatty acids in the meat of feedlot lambs.

High-potency white-rot fungal strains and duration of fermentation to optimize corn straw as ruminant feed

Five white-rot fungi Pleurotus ostreatus, Lentinus edodes, Hericium erinaceus, Pleurotus eryngii and Flammulina filiformis were studied (solid-state incubation and in vitro gas production) to determine lignin degradation and optimal duration of fermentation of corn straw. All fungi significantly decreased lignin, with optimal reductions after 28 d. Although cellulose also decreased, L. edodes and P. eryngii minimized these losses. In intro dry matter digestibility, total volatile fatty acid concentration and total gas production of fermented corn straw decreased (P < 0.001) as fermentation was prolonged, with improved rumen fermentability for all fungal treatments except F. filiformis. Total gas production in L. edodes did not decrease but peaked on day 28, whereas F. filiformis reduced methane emission. In conclusion, fermentation of corn straw with P. eryngii or L. edodes for 28 d degraded lignin and improved nutritional value as ruminant feed.

Chitosan-chelated zinc modulates cecal microbiota and attenuates inflammatory response in weaned rats challenged with Escherichia coli

Escherichia coli (E. coli) infection is very common among young growing animals, and zinc supplementation is often used to alleviate inflammation induced by this disease. Therefore, the objective of this study was to evaluate whether chitosan-chelated zinc (CS-Zn) supplementation could attenuate gut injury induced by E. coli challenge and to explore how CS-Zn modulates cecal microbiota and alleviates intestinal inflammation in weaned rats challenged with E. coli. 36 weaned rats (55.65 ± 2.18 g of BW, n = 12) were divided into three treatment groups consisting of unchallenged rats fed a basal diet (Control) and two groups of rats challenged with E. coli and fed a basal diet or a diet containing 640 mg/kg CS-Zn (E. coli + CS-Zn, containing 50 mg/kg Zn) for a 14-day experiment. On days 10 to 12, each rat was given 4 ml of E. coli solution with a total bacteria count of 10¹⁰ CFU by oral gavage daily or normal saline of equal dosage. CS-Zn supplementation mitigated intestinal morphology impairment (e.g. higher crypt depth and lower macroscopic damage index) induced by E. coli challenge (P < 0.05), and alleviated the increase of Myeloperoxidase (MPO) activity after E. coli challenge (P < 0.05). 16S rRNA sequencing analyses revealed that E. coli challenge significantly increased the abundance of Verrucomicrobia and E. coli (P < 0.05). However, CS-Zn supplementation increased the abundance of Lactobacillus and decreased the relative abundance of Proteobacteria, Desulfovibrio and E. coli (P < 0.05). The concentrations of butyrate in the cecal digesta, which decreased due to the challenge, were higher in the E. coli + CS-Zn group (P < 0.05). In addition, CS-Zn supplementation significantly prevented the elevation of pro-inflammatory cytokines IL-6 concentration and up-regulated the level of anti-inflammatory cytokines IL-10 in cecal mucosa induced by E. coli infection (P < 0.05). In conclusion, these results indicate that CS-Zn produces beneficial effects in alleviating gut mucosal injury of E. coli challenged rats by enhancing the intestinal morphology and modulating cecal bacterial composition, as well as attenuating inflammatory response.

Serum metabolomic fingerprints of lambs fed chitosan and its association with performance and meat quality traits

Chitosan (CHI) is a natural biopolymer with antimicrobial, anti-inflammatory, antioxidant and digestive modulatory effects, which can be used in the ruminant diet to replace antibiotics. The aim of this study was to evaluate the effects of CHI on lamb growth traits, nutrients digestibility, muscle and fatty deposition, meat fatty acid (FA) profile, meat quality traits and serum metabolome. Thirty 30-month-old male lambs, half Suffolk and half Dorper, with an average BW of 21.65 ± 0.86 kg, were fed in a feedlot system for a total of 70 days. The lambs were separated into two groups according to the diet: the control (CON) group which received the basal diet and the CHI group which received the basal diet with the addition of CHI as 2 g/kg of DM in the diet. Lambs supplemented with CHI had a greater (P < 0.05) final BW, DM intake, final body metabolic weight (P < 0.05) and lower residual feed intake than the CON group. Animals fed CHI had a greater (P < 0.05) starch digestibility at 14 and 28 days, average daily gain at 14, 42 and 56 days, greater feed efficiency at 28 days and feed conversation at 14 and 42 days in feedlot. Most of the carcass traits were not affected (P > 0.05) by the treatment; however, the CHI supplementation improved (P < 0.05) dressing and longissimus muscle area. The treatments had no effect (P > 0.05) on the meat colour and other quality measurements. Meat from the CHI-fed lambs had a greater concentration (P < 0.05) of oleic-cis-9 acid, linoleic acid, linolenic-trans-6 acid, arachidonic acid and eicosapentaenoic acid. According to the variable importance in projection score, the most important metabolites to differentiate between the CON and the CHI group were hippurate, acetate, hypoxanthine, arginine, malonate, creatine, choline, myo-inositol, 2-oxoglutarate, alanine, glycerol, carnosine, histidine, glutamate and 3-hydroxyisobutyrate. Similarly, fold change (FC) analysis highlighted succinate (FC = 1.53), arginine (FC = 1.51), hippurate (FC = 0.68), myo-inositol (FC = 1.48), hypoxanthine (FC = 1.45), acetate (FC = 0.73) and malonate (FC = 1.35) as metabolites significantly different between groups. In conclusion, the present data showed that CHI changes the muscle metabolism improving muscle mass deposition, the lamb's performance and carcass dressing. In addition, CHI led to an alteration in the FA metabolism, changes in the meat FA profile and improvements in meat quality.

Chitosan associated with whole raw soybean in diets for Murrah buffaloes on ruminal fermentation, apparent digestibility and nutrients metabolism

This study aimed to investigate the effects of chitosan and whole raw soybean on nutrient intake, apparent digestibility, nitrogen utilization, microbial protein synthesis, blood metabolites, feeding behavior, ruminal fermentation, digesta kinetics, and reticular flow of nutrients of buffaloes. Four ruminally-cannulated Murrah buffaloes (351 ± 15 kg of initial BW) were randomly assigned according to a 4 × 4 Latin square design. Treatments were arranged as 2 × 2 factorial arrangement: the first factor was whole raw soybean (WRS), and the second factor was chitosan (CHI) with or without their inclusion in diets. Intake and apparent digestibility of ether extract (p < .01; p = .04, respectively), non-fiber carbohydrates intake (p = .03) and apparent ruminal digestibility of dry matter (p = .01) were affected by diets. An interaction effect or tendency was observed for microbial nitrogen (p = .09), concentrations, ruminal ammonia nitrogen (p = .05), total volatile fatty acid (p = .03). Association of chitosan with whole raw soybean has potential effects as a modulator of rumen fermentation; therefore, chitosan can be applied as an alternative non-ionophore for Murrah buffaloes.

Effect of natural feed additives on meat quality and caecotrophic fatty acid profile of New Zealand rabbits

ABSTRACT The objectives of this research were to evaluate the effects of commercial probiotic and chitosan as food additives on the quality and meat composition of 36 New Zealand White rabbits (57 ± 8 days old and 1,648 ± 0.194 kg) and on the fatty acid profile of caecotrophs. The treatments were CT (diets without inclusion of additives), PRO (inclusion of 4 g / kg of commercial probiotic) and CHI (inclusion of 4 g / kg of chitosan). The additives increased triglycerides and decreased urea compared to the control group, as well as increased oleic and linoleic acids, Ʃ unsaturated, Ʃ monounsaturated and Ʃ polyunsaturated in caecotrophs. CHI animals showed a decrease in myristic and palmitic acids compared to PRO. CHI decreased the meat's crude protein and the meat's fat. In addition, there was a decrease in omega-3, omega-6 and the relationship unsaturated and saturated fatty acids for the CHI group and an increase in erucic acid and a decrease in the rate of hypocholesterolemic acids. As a conclusion, the data showed that the animals that ingested probiotic had better meat quality, for having better fatty acid profile and hypocholesterolemic index, compared to the treatment with chitosan. The additives improved the caecotrophs fatty acid profile.

Combining Crude Glycerin with Chitosan Can Manipulate In Vitro Ruminal Efficiency and Inhibit Methane Synthesis

It was hypothesized that the combination of glycerin and chitosan improves ruminal fermentation efficiency via an enhanced propionate (C3) and reduces in vitro CH₄ production. This was explored through in vitro gas production with substrates containing crude glycerin, which replaced cassava chips in the studied ration. The experimental design was organized following a 3 × 3 factorial in completely randomized design and the arrangement of treatments were different levels of crude glycerin supplementations 0, 10.5, and 21% of total mixed ration (TMR) and chitosan levels were added at 0, 1, and 2% dry matter (DM) of substrate. Then, 0.5 g of TMR substrates were added into 40 mL bottles, together with respective doses of chitosan and then incubated at 39 °C. The dietary treatments were performed in three replicates within the incubation, and incubations were repeated on three separate days (runs). No interactions were found between crude glycerin and chitosan doses in terms of theoretical maximum of asymptotic gas production (b), rate of gas production (c), the discrete lag time prior to gas production (L), or the cumulative gas production at 96 h of incubation (p > 0.05). Cumulative gas production at 96 h of incubation was similar among the doses of crude glycerin and levels of chitosan, which ranged from 64.27 to 69.66 mL/g DM basis of substrate (p > 0.05). The concentration of ruminal NH₃-N after 2 and 4 h of incubation ranged from 14.61 to 17.10 mg/dL and did not change with the addition of crude glycerin with chitosan (p > 0.05). The concentration of CH₄ after 2 h of incubation did not change among treatments (p > 0.05), whereas after 4 h of incubation, CH₄ synthesis was significantly reduced by enhancing doses of crude glycerin and chitosan (p < 0.05). The combination of 21% of crude glycerin in TMR with 2% chitosan depressed CH₄ production as much as 53.67% when compared to the non-supplemented group. No significant crude glycerin and chitosan interaction effect was detected for in vitro digestibility of nutrients after incubation for 12 and 24 h using the in vitro gas production technique (p > 0.05). In addition, no significant changes (p > 0.05) were observed in total volatile fatty acids, acetate (C2) or butyrate content among treatments and between the main effects of crude glycerin with chitosan. At 4 h of incubation, ruminal C3 content and the C2 to C3 ratio changed significantly when crude glycerin and chitosan was added (p < 0.05). The 21% crude glycerin incorporate into TMR, in combination with 2% additional chitosan, increased C3 content by 26.41%, whereas the ratio of C2 to C3 was reduced by 31% when compared to the control group. Propionate concentration increased by 11.75% when increasing levels of chitosan at 2% of substrate, whereas the C2 to C3 ratio decreased by 13.99% compared to the 0% chitosan group. The inclusion of crude glycerin at 21% in TMR diets with chitosan supplementation at 2% enhanced ruminal propionate concentration and reduced methane production without causing any detrimental effect on the gas kinetics or nutrient digestibility.

The Role of Chitosan as a Possible Agent for Enteric Methane Mitigation in Ruminants

Simple Summary

Ruminant husbandry is one the largest contributors to greenhouse gas emissions from the agriculture sector, particularly of methane gas, which is a byproduct of the anaerobic fermentation of structural and non-structural carbohydrates in the rumen. Increasing the efficiency of production systems and decreasing its environmental burden is a global commitment, thus methane mitigation is a strategy in which to reach these goals by rechanneling metabolic hydrogen (H₂) into volatile fatty acids (VFA) to reduce the loss of energy as methane in the rumen, which ranges from 2% (grain rations) to 12% (poor-quality forage rations) of gross energy intake. A strategy to achieve that goal may be through the manipulation of rumen fermentation with natural compounds such as chitosan. In this review, we describe the effects of chitosan on feed intake and rumen fermentation, and present some results on methanogenesis. The main compounds with antimethanogenic properties are the secondary metabolites, which are generally classified into five main groups: saponins, tannins, essential oils, organosulfurized compounds, and flavonoids. Novel compounds of interest include chitosan obtained by the deacetylation of chitin, with beneficial properties such as biocompatibility, biodegradability, non-toxicity, and chelation of metal ions. This compound has shown its potential to modify the rumen microbiome, improve nitrogen (N) metabolism, and mitigate enteric methane (CH₄) under some circumstances. Further evaluations in vivo are necessary at different doses in ruminant species as well as the economic evaluation of its incorporation in practical rations.

Abstract

Livestock production is a main source of anthropogenic greenhouse gases (GHG). The main gases are CH₄ with a global warming potential (GWP) 25 times and nitrous oxide (N₂O) with a GWP 298 times, that of carbon dioxide (CO₂) arising from enteric fermentation or from manure management, respectively. In fact, CH₄ is the second most important GHG emitted globally. This current scenario has increased the concerns about global warming and encouraged the development of intensive research on different natural compounds to be used as feed additives in ruminant rations and modify the rumen ecosystem, fermentation pattern, and mitigate enteric CH₄. The compounds most studied are the secondary metabolites of plants, which include a vast array of chemical substances like polyphenols and saponins that are present in plant tissues of different species, but the results are not consistent, and the extraction cost has constrained their utilization in practical animal feeding. Other new compounds of interest include polysaccharide biopolymers such as chitosan, mainly obtained as a marine co-product. As with other compounds, the effect of chitosan on the rumen microbial population depends on the source, purity, dose, process of extraction, and storage. In addition, it is important to identify compounds without adverse effects on rumen fermentation. The present review is aimed at providing information about chitosan for dietary manipulation to be considered for future studies to mitigate enteric methane and reduce the environmental impact of GHGs arising from livestock production systems. Chitosan is a promising agent with methane mitigating effects, but further research is required with in vivo models to establish effective daily doses without any detrimental effect to the animal and consider its addition in practical rations as well as the economic cost of methane mitigation.

Effects of Mannan Oligosaccharides on Gas Emission, Protein and Energy Utilization, and Fasting Metabolism in Sheep

Simple Summary

Mannan oligosaccharides (MOS) are a promising feed additive to improve animal health, immune capacity, and antioxidation. Based on the previous studies, we carried out three experiments to investigate the effects of MOS on the gas emission, protein and energy utilization, and fasting metabolism of sheep. The results showed that 2.0% MOS supplementation led to the lowest in vitro CO₂ production and lower CH₄ production and decreased in vivo intake. However, it also decreased urine nitrogen excretion and energy released as CH₄, and then improved the utilization of crude protein and energy of sheep. There were no differences in the parameters of respiration and energy metabolism of sheep under the fasting condition. The findings indicated that MOS slightly affected the gas emission and nutrients and energy utilization of sheep.

Abstract

This study investigated the effects of mannan oligosaccharides (MOS) on in vitro and in vivo gas emission, utilization of crude protein (CP) and energy, and relative parameters of sheep under fasting metabolism conditions. In vitro gas productions were evaluated over 12 h in sheep diets containing different amounts of MOS (from 0% to 6.0%/kg, the increment was 0.5%). A control experiment was used to assess the gas emission, utilization of CP and energy, and fasting metabolism in control sheep and sheep treated with 2.0% MOS over 24 days (d). The results showed that 2.0% MOS supplementation led to the lowest in vitro CO₂ production and less CH₄ production, while also leading to decrease in vivo nutrients intake, CP and energy excretion, digested and retained CP, and energy released as CH₄ (p < 0.05). Furthermore, 2.0% MOS supplementation appeared to decrease in vivo O₂ consumption and CH₄ production per metabolic body weight (BW^0.75), and increase the CP retention rate of sheep (p < 0.074). MOS did not affect other parameters, along with the same parameters of sheep under fasting metabolism conditions (p > 0.05). The findings indicate MOS has only slight effects on the gas emission and nutrients and energy metabolism of sheep.

Effects of chitosan and whole raw soybeans on ruminal fermentation and bacterial populations, and milk fatty acid profile in dairy cows

The objective of this study was to evaluate whether providing chitosan (CHI) to cows fed diets supplemented with whole raw soybeans (WRS) would affect the nutrient intake and digestibility, ruminal fermentation and bacterial populations, microbial protein synthesis, N utilization, blood metabolites, and milk yield and composition of dairy cows. Twenty-four multiparous Holstein cows (141 ± 37.1 d in milk, 38.8 ± 6.42 kg/d of milk yield; mean ± SD) were enrolled to a 4 × 4 Latin square design experiment with 23-d periods. Cows were blocked within Latin squares according to milk yield, days in milk, body weight, and rumen cannula (n = 8). A 2 × 2 factorial treatment arrangement was randomly assigned to cows within blocks. Treatments were composed of diets with 2 inclusion rates of WRS (0 or 14% diet dry matter) and 2 doses of CHI (0 or 4 g/kg of dry matter, Polymar Ciência e Nutrição, Fortaleza, Brazil). In general, CHI+WRS negatively affected nutrient intake and digestibility of cows, decreasing milk yield and solids production. The CHI increased ruminal pH and decreased acetate to propionate ratio, and WRS reduced NH3-N concentration and acetate to propionate in the rumen. The CHI reduced the relative bacterial population of Butyrivibrio group, whereas WRS decreased the relative bacterial population of Butyrivibrio group, and Fibrobacter succinogenes, and increased the relative bacterial population of Streptococcus bovis. No interaction effects between CHI and WRS were observed on ruminal fermentation and bacterial populations. The CHI+WRS decreased N intake, microbial N synthesis, and N secreted in milk of cows. The WRS increased N excreted in feces and consequently decreased the N excreted in urine. The CHI had no effects on blood metabolites, but WRS decreased blood concentrations of glucose and increased blood cholesterol concentration. The CHI and WRS improved efficiency of milk yield of cows in terms of fat-corrected milk, energy-corrected milk, and net energy of lactation. The CHI increased milk concentration [g/100 g of fatty acids (FA)] of 18:1 trans-11, 18:2 cis-9,cis-12, 18:3 cis-9,cis-12,cis-15, 18:1 cis-9,trans-11, total monounsaturated FA, and total polyunsaturated FA. The WRS increased total monounsaturated FA, polyunsaturated FA, and 18:0 to unsaturated FA ratio in milk of cows. Evidence indicates that supplementing diets with unsaturated fat sources along with CHI negatively affects nutrient intake and digestibility of cows, resulting in less milk production. Diet supplementation with CHI or WRS can improve feed efficiency and increases unsaturated FA concentration in milk of dairy cows.

Effects of low-molecular-weight chitosan on the growth performance, intestinal morphology, barrier function, cytokine expression and antioxidant system of weaned piglets

Background

Chitosan was used as an alternative to promote the growth of weaned piglets. And low-molecular-weight chitosan (LC) is one of chitosan derivatives and maintain beneficial biological properties of chitoson. The present experiment was carried out to examine the effects of LC on the growth performance, intestinal morphology, barrier function, cytokine expression, and antioxidant system of weaned piglets.

Results

A total of 40 piglets weaned at 21 d of age, with average body weight 6.37 ± 0.08 kg, were randomly assigned (5 pens/diet; 4 pigs/pen) to 2 treatments (a basal diet and the basal diet supplemented with 50 mg/kg LC) and were fed for 28 d. Compared with the control group, average daily feed intake (ADFI), and the expression of intestinal barrier protein ZO-1 was increased (P < 0.05) when the piglets fed the diet supplemented with LC. No significant differences were found in average daily gain (ADG, P > 0.05), gain-to-feed ratio (G:F, P > 0.05), the incidence of diarrhea (P > 0.05), or the antioxidant capacity (P > 0.05) between two groups. The expression of IL-1β and TNF-α in jejunal mucosa were significantly decreased (P < 0.05) in piglets fed the LC-supplemented diet in comparison to the control.

Conclusion

The results of this study indicate that dietary supplementation with LC at 50 mg/kg was effective for enhancing the growth performance in weaned piglets, improving intestinal barrier function and alleviating intestinal inflammation.

Effects of adding mannan oligosaccharides on digestibility and metabolism of nutrients, ruminal fermentation parameters, immunity, and antioxidant capacity of sheep

The purpose of this study was to investigate the effects of adding mannan-oligosaccharides (MOS) on the following parameters in sheep: digestibility and retention rate of nutrients, ruminal fermentation, immunity, and antioxidant capacity. Twelve healthy crossbred wethers (Suffolk ♂ × Small tail Han-yang ♀) with external ruminal fistula and similar body weights (28.04 ± 2.07 kg) were fed individually four treatments, three repeats of each treatment. The wethers diets were supplemental MOS at 0%, 1.2%, 1.6%, and 2.0%·kg-1 of basal diet (as fed basis). The experiment lasted 17 d, including 10 d of acclimation and 7 d of formal experimentation. The results showed that MOS did not influence the apparent digestibility and retention rate of nutrients, ruminal fermentation, and immunity or concentration of serum nitric oxide and activity of serum nitric oxide synthase (P ≥ 0.07). However, the apparent digestibility of neutral detergent fiber and acid detergent fiber at MOS supplementation rates of 1.6% and 2.0% both tended to be greater than the control group (P ≤ 0.103). There was also moderate evidence that MOS might increase the nitrogen retention rate (P = 0.082). MOS increased the antioxidant ability of sheep (P ≤ 0.018), especially at a dose of 1.6%: an increase in activity of total superoxide dismutase (P = 0.007), glutathione peroxidase (P = 0.018) and total antioxidant capacity (P < 0.001), and a decrease in concentration of malondialdehyde (P < 0.001) were found. The results indicated that in sheep MOS improved fiber digestion, N retention and some antioxidant abilities, but these effects may be too small to improve health and performance.

Relationship between thiamine and subacute ruminal acidosis induced by a high-grain diet in dairy cows

Two experiments were conducted to reveal the effects of grain-induced subacute rumen acidosis (SARA) on thiamine status in blood and rumen fluid in dairy cows. In both experiments, 6 multiparous, rumen-fistulated Holstein dairy cows were used in a 2-treatment, 2-period crossover design. Each experimental period consisted of 21d (total of 42d). Experiment 1 was to investigate the effects of SARA on thiamine status in blood and rumen fluid. Treatments were either control (20% starch, dry matter basis) or SARA-inducing diet (SAID, 33.2% starch, dry matter basis). In experiment 2, the effects of dietary thiamine supplementation on attenuating SARA and ruminal fermentation characteristics in dairy cows were studied. All cows received the same SAID diet during the whole experimental period; treatments were with or without thiamine (180mg of thiamine/kg of dry matter intake). In both experiments, rumen fluid samples were collected at 0, 3, 6, 9, and 12h after morning feeding on d 21 and 42 of the experiments for measurement of pH, thiamine, volatile fatty acid, and lactate contents. Peripheral blood was also collected at 3h after morning feeding on d 21 and 42 to measure thiamine, carbohydrate metabolites, and enzyme activities. In experiment 1, cows fed the SAID diet had lower ruminal and plasma thiamine concentrations and higher lactate than cows fed the control diet. The ruminal thiamine contents were positively related to pH and the concentrations of acetate in the rumen, and negatively correlated with the lactate contents. Experiment 2 demonstrated that ruminal pH and the concentrations of thiamine, acetate, and total volatile fatty acids in the rumen were increased, whereas ruminal lactate contents were reduced by thiamine supplementation. The concentrations of lactate and the activity of lactate dehydrogenase in blood were reduced in the thiamine supplemented group, and the opposite was true for the nonesterified fatty acids and α-ketoneglutarate dehydrogenase contents. In conclusion, the thiamine status was affected by SARA in dairy cows and ruminal infusion of thiamine could help attenuate SARA by improving theproportions of ruminal volatile fatty acids and reducing lactate contents in rumen fluid and blood.

Effects of chitosan on nutrient digestibility, methane emissions, and in vitro fermentation in beef cattle

Chitosan was evaluated as a feed additive to mitigate in vivo CH4 emissions in beef cattle. Twenty-four crossbred heifers (BW = 318 ± 35 kg) were used in a randomized block design replicated in 2 periods. The design included a 2 × 3 factorial arrangement of treatments, which included diet (high concentrate [HC] or low concentrate [LC]) and 0.0, 0.5, or 1.0% of chitosan inclusion (DM basis). Diets were offered ad libitum and individual intake was recorded. An in vitro experiment to analyze chitosan’s effect on fermentation parameters and gas production kinetics was performed. A diet effect (P < 0.01) was observed for CH4 emissions expressed as grams/day, grams/kilogram of BW0.75, and grams/kilogram of DMI. Heifers consuming the LC diet produced 130 g of CH4/d vs. 45 g of CH4/d in those consuming the HC diet. Incubation fluid pH increased linearly (P < 0.05) when chitosan was included in HC substrates. In vitro CH4 production was not affected (P > 0.10) by chitosan in HC substrate; however, when incubated with the LC substrate, CH4 production increased quadratically (P < 0.01) as chitosan inclusion increased. A digestibility marker × diet interaction occurred (P < 0.05) for DM, OM, CP, NDF, and ADF digestibility. Diet × chitosan interactions (P < 0.05) occurred for DM, OM, NDF, and ADF digestibility when Cr2O3 was used. When TiO2 was used, diet × chitosan interactions (P < 0.05) were observed for NDF and ADF. However, using indigestible NDF as an internal marker, DM and OM digestibility were improved (P < 0.05) by 21 and 19%, respectively, when chitosan was included in LC diets. In conclusion, feeding up to 1% of chitosan (DM basis) to heifers consuming a LC diet increased apparent total tract digestibility of nutrients. Enteric CH4 emissions were not affected by chitosan feeding, regardless of type of diet, and heifers consuming a 36% concentrate diet produced 2.6 times more methane per day than those consuming an 85% concentrate diet.

In vitro screening of natural feed additives from crustaceans, diatoms, seaweeds and plant extracts to manipulate rumen fermentation

BACKGROUND

Eight natural products from animal, unicellular algae, brown seaweed and plant origins were chosen according to their theoretical antimicrobial activity: Diatomaceous earths (DE), insoluble chitosan (ICHI), soluble chitosan (CHI), seaweed meal (SWM), Ascophyllum nodosum (ASC), Laminaria digitata (LAM), neem oil (NOIL) and an ivy fruit extract rich in saponins (IVY). Dose-response incubations were conducted to determine their effect on rumen fermentation pattern and gas production, while their anti-protozoal activity was tested using (14) C-labelled bacteria.

RESULTS

DE, SWM, NOIL and ICHI had very small effects on rumen function when used at inclusion rate up to 2 g L(-1) . ASC had anti-protozoal effects (up to -23%) promoting a decrease in gas production and methanogenesis (-15%). LAM increased VFA production (+7%) and shifted from butyrate to acetate. CHI also shifted fermentation towards propionate production and lower methane (-23%) and protozoal activity (-56%). IVY decreased protozoal activity (-39%) and ammonia concentration (-56%), as well as increased feed fermentation (+11% VFA concentration) and shifted from acetate to propionate production.

CONCLUSIONS

ASC, LAM, CHI and IVY showed promising potential in vitro as feed additives to improve rumen function, thus more research is needed to investigate their mode of action in the rumen microbial ecosystem. © 2015 Society of Chemical Industry.

Effects and mode of action of chitosan and ivy fruit saponins on the microbiome, fermentation and methanogenesis in the rumen simulation technique

This study investigates the effects of supplementing a control diet (CON) with chitosan (CHI) or ivy fruit saponins (IVY) as natural feed additives. Both additives had similar abilities to decrease rumen methanogenesis (–42% and –40%, respectively) using different mechanisms: due to its antimicrobial and nutritional properties CHI promoted a shift in the fermentation pattern towards propionate production which explained about two thirds of the decrease in methanogenesis. This shift was achieved by a simplification of the structure in the bacterial community and a substitution of fibrolytic (Firmicutes and Fibrobacteres) by amylolytic bacteria (Bacteroidetes and Proteobacteria) which led to greater amylase activity, lactate and microbial protein yield with no detrimental effect on feed digestibility. Contrarily, IVY had negligible nutritional properties promoting minor changes in the fermentation pattern and on the bacterial community. Instead, IVY modified the structure of the methanogen community and decreased its diversity. This specific antimicrobial effect of IVY against methanogens was considered its main antimethanogenic mechanism. IVY had however a negative impact on microbial protein synthesis. Therefore, CHI and IVY should be further investigated in vivo to determine the optimum doses which maintain low methanogenesis but prevent negative effects on the rumen fermentation and animal metabolism.

Rumen function is generally suboptimal leading to loses in the form of methane and nitrogen, analysis of the rumen microbiome is vital to understand the mode of action of new feed additives to improve rumen function.

Effects of chitosan on body weight gain, growth hormone and intestinal morphology in weaned pigs

The study was conducted to determine the effects of chitosan on the concentrations of GH and IGF-I in serum and small intestinal morphological structure of piglets, in order to evaluate the regulating action of chitosan on weaned pig growth through endocrine and intestinal morphological approaches. A total of 180 weaned pigs (35 d of age; 11.56±1.61 kg of body weight) were selected and assigned randomly to 5 dietary treatments, including 1 basal diet (control) and 4 diets with chitosan supplementation (100, 500, 1,000 and 2,000 mg/kg, respectively). Each treatment contained six replicate pens with six pigs per pen. The experiment lasted for 28 d. The results showed that the average body weight gain (BWG) of pigs was improved quadratically by dietary chitosan during the former 14 d and the later 14 d after weaned (p<0.05). Furthermore, dietary supplementation of chitosan tended to quadratically increase the concentration of serum GH on d 14 (p = 0.082) and 28 (p = 0.087). Diets supplemented with increasing levels of chitosan increased quadratically the villus height of jejunum and ileum on d 14 (p = 0.089, p<0.01) and 28 (p = 0.074, p<0.01), meanwhile, chitosan increased quadratically the ratio of villus height to crypt depth in duodenum, jejunum and ileum on d 14 (p<0.05, p = 0.055, p<0.01) and 28 (p<0.01, p<0.01, p<0.01), however, it decreased quadratically crypt depth in ileum on d 14 (p<0.05) and that in duodenum, jejunum and ileum on d 28 (p<0.01, p<0.05, p<0.05). In conclusion, these results indicated that chitosan could quadratically improve growth in weaned pigs, and the underlying mechanism may due to the increase of the serum GH concentration and improvement of the small intestines morphological structure.

Subacute ruminal acidosis challenge changed in situ degradability of feedstuffs in dairy goats

This study investigated the effects of wheat-induced subacute ruminal acidosis (SARA) on rumen bacterial populations and in situ degradabilities of NDF, starch, and crude protein of feeds. Four multiparous dairy goats (BW=60±3.3kg) fitted with ruminal cannulas were assigned to a 2×2 crossover design (28-d treatment periods separated by a 7-d washout interval). The treatment diets consisted of 2 levels of cracked wheat: 0 (control, corn based concentrate) and 35% (diet-induced SARA, wheat-based concentrate), with a constant forage- (45% alfalfa hay and 5% corn silage of DM) to-concentrate (50% of DM) ratio. Results indicate that diets with a 35% wheat decreased ruminal pH (6.21 vs. 5.98) and increased the duration (1.13 vs. 4.72h/d) and area (0.12 vs. 0.78 pH × h/d) of ruminal pH below 5.6 and induced SARA. The SARA increased ruminal total volatile fatty acid concentration, from 105.0 to 123.8mM, and decreased the acetate molar proportion (62.8 vs. 56.6mol/100mol) and the acetate-to-propionate ratio (3.5 vs. 2.8). Compared with the control group, SARA decreases the relative abundance of Fibrobacter succinogenes (-59.3%) and Ruminococcus flavefaciens (-68.4%), whereas it increased Succinimonas amylolytica (198.1%) and Ruminobacter amylophilus (125.2%). The SARA decreased 24- and 48-h dry matter (DM) and neutral detergent fiber (NDF) degradabilities of corn silage. The 48-h degradabilities of DM (51.0 vs. 48.2%) and NDF (40.3 vs. 36.0%) in alfalfa hay were not affected by SARA, but the SARA tended to reduce the 24-h DM (49.6 vs. 46.3%) and NDF (37.8 vs. 33.2%) degradabilities. The effective ruminal degradabilities of DM and NDF in alfalfa hay and corn silage were reduced during SARA. In situ degradability parameters of DM and starch of wheat were not affected by SARA, but starch degradability of corn (9.5 vs. 13.3%/h) increased. The SARA reduced in situ 12-h degradabilities of DM and crude protein of soybean meal and extruded soybean without affecting the degradabilities of the other protein supplements (corn gluten meal, cottonseed meal, corn dried distillers grains with solubles, rapeseed meal, and wheat germ meal). These results indicated that the cracked wheat-induced SARA reduced the degradation of NDF in roughages and that of protein in soybean meal (-19.8%) and extruded soy (-18.9%) and increased the starch degradability in corn, due to the increased amylolytic bacteria and decreased cellulolytic bacteria counts in the rumen.