The effects of rumen nitrogen balance on in vitro rumen fermentation and microbial protein synthesis vary with dietary carbohydrate and nitrogen sources

Effects of Centella asiatica Extracts on Rumen In Vitro Fermentation Characteristics and Digestibility

Two in vitro experiments were conducted to evaluate the effects of Centella asiatica extract (CAE) supplementation on the rumen's in vitro fermentation characteristics. In the first experiment, CAE with five concentrations (C: 0%; T1: 3.05%; T2: 6.1%; T3: 12.2%; and T4: 24.4% CAE in diet) was supplemented in the rumen fluid and incubated for 6, 24, and 48 h to determine the optimal dosage. The total gas and methane production increased in all incubation times, and the total volatile fatty acids increased at 6 and 48 h. Ammonia nitrogen, branched chain volatile fatty acids, acetate, and butyrate were increased by CAE supplementation. T1 was chosen as the optimal dosage based on the total volatile fatty acids, branched chain volatile fatty acids, and ammonia nitrogen production. The CAE with the identified optimal dosage (T1) was incubated to identify its effect on the rumen's in vitro degradability in the second experiment. The CAE supplementation did not influence the in vitro dry matter, crude protein, or neutral detergent fiber degradability. In conclusion, CAE has no CH4 abatement or digestion promotion effects. However, CAE could be utilized as a feed additive to increase the rumen's total volatile fatty acid production without an adverse effect on the in vitro dry matter, crude protein, or neutral detergent fiber degradability.

Unveiling the breadmaking transformation: Structural and functional insights into Arabinoxylan

To understand the changes in arabinoxylan (AX) during breadmaking, multi-step enzyme digestion was conducted to re-extract arabinoxylan (AX-B) from AX-fortified bread. Their structural changes were compared using HPSEC, HPAEC, FT-IR, methylation analysis, and 1H NMR analysis; their properties changes in terms of enzymatic inhibition activities and in vitro fermentability against gut microbiota were also compared. Results showed that AX-B contained a higher portion of covalently linked protein while the molecular weight was reduced significantly after breadmaking process (from 677.1 kDa to 15.6 kDa); the structural complexity of AX-B in terms of the degree of branching was increased; the inhibition activity against α-amylase (76.81 % vs 73.89 % at 4 mg/mL) and α-glucosidase (64.43 % vs 58.08 % at 4 mg/mL) was improved; the AX-B group produced a higher short-chain fatty acids concentration than AX (54.68 ± 7.86 mmol/L vs 44.03 ± 4.10 mmol/L). This study provides novel knowledge regarding the structural and properties changes of arabinoxylan throughout breadmaking, which help to predict the health benefits of fibre-fortified bread and achieve precision nutrition.

Effect of Dietary Rumen-Degradable Starch to Rumen-Degradable Protein Ratio on In Vitro Rumen Fermentation Characteristics and Microbial Protein Synthesis

The objective of this study was to investigate the effects of dietary rumen-degradable starch (RDS, g/kg of DM) to rumen-degradable protein (RDP, g/kg of DM) ratios (SPR) on in vitro rumen fermentation characteristics and microbial protein synthesis (MCPS). Treatments were eight diets with SPR of 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 and 2.6 and were formulated to be isoenergetic, isonitrogenous, and isostarch. Substrates were anaerobically incubated in sealed culture vials (100 mL) for 6, 24 or 48 h. Three incubation runs were conducted within two consecutive weeks. With the increase of the dietary SPR, the gas production (GP), in vitro dry matter disappearance (IVDMD) and concentration of MCPS and total volatile fatty acids (TVFA) linearly increased after 6 h of incubation (p ≤ 0.01), whereas they quadratically increased and peaked at the SPR of 2.3 after 24 and 48 h of incubation (p < 0.05). In response to dietary SPR increasing, the in vitro neutral detergent fiber disappearance (IVNDFD) quadratically increased (p < 0.01), and the ammonia nitrogen (NH3-N) concentration linearly decreased (p < 0.01) after 6, 24 and 48 h of incubation. Based on the presented results, an SPR of 2.3 is recommended for formulating a diet due to its greatest IVDMD, IVNDFD, GP, TVFA and MCPS. However, as the results obtained are strictly dependent on the in vitro conditions, further in vivo studies are needed to verify our findings.

Lipid microspheres containing urea for slow release of non-protein N in ruminant diets

ContextUrea is widely used in ruminant diets as a source of non-protein nitrogen (NPN), partially substituting for true protein in feed, but high levels of urea in the diet may cause toxicity.AimsThis study investigated the microencapsulation of urea in carnauba wax for slow release in the rumen to improve the N efficiency and growth of sheep.MethodsTwo microencapsulated systems were developed with urea:carnauba wax ratios (w/w) of 1:2 (U12) and 1:4 (U14). Based on the initial characterisation, only U12 was examined in an in vivo experiment with Santa Ines crossbred male sheep (n=40) initially weighing 28±0.6kg at 270 days of age. The experimental arrangement was a completely randomised design, and the animals were distributed into four treatments; i.e. four levels of inclusion (0, control; 15; 30; and 45g/kg DM) of microencapsulated urea in the diet.Key resultsThe dietary inclusion of microencapsulated urea was associated with linear increases (P≤0.05) in the intake of DM and metabolisable energy, the digestibility of crude protein, non-fibrous carbohydrates and fibre fractions, and N balance. Additionally, liveweight gain and feed efficiency increased quadratically (P&lt;0.001). There were also linear reductions (P&lt;0.001) in blood urea and urinary urea concentrations.ConclusionsThe study demonstrated that the inclusion of up to 30g/kg U12 microencapsulated urea can be recommended as a source of slow-release urea in sheep diets since it improved the performance and feed efficiency and promoted lower concentrations of blood urea and urinary urea.ImplicationsThe use of urea microencapsulated in carnauba wax can reduce the risk of urea toxicity and provide a safer way to supply NPN to ruminants and improve N utilisation.

Research Advances of d-allulose: An Overview of Physiological Functions, Enzymatic Biotransformation Technologies, and Production Processes

d-allulose has a significant application value as a sugar substitute, not only as a food ingredient and dietary supplement, but also with various physiological functions, such as improving insulin resistance, anti-obesity, and regulating glucolipid metabolism. Over the decades, the physiological functions of d-allulose and the corresponding mechanisms have been studied deeply, and this product has been applied to various foods to enhance food quality and prolong shelf life. In recent years, biotransformation technologies for the production of d-allulose using enzymatic approaches have gained more attention. However, there are few comprehensive reviews on this topic. This review focuses on the recent research advances of d-allulose, including (1) the physiological functions of d-allulose; (2) the major enzyme families used for the biotransformation of d-allulose and their microbial origins; (3) phylogenetic and structural characterization of d-allulose 3-epimerases, and the directed evolution methods for the enzymes; (4) heterologous expression of d-allulose ketose 3-epimerases and biotransformation techniques for d-allulose; and (5) production processes for biotransformation of d-allulose based on the characterized enzymes. Furthermore, the future trends on biosynthesis and applications of d-allulose in food and health industries are discussed and evaluated in this review.

The production of single cell protein from biogas slurry with high ammonia-nitrogen content by screened Nectaromyces rattus

In this study, a novel method was proposed to obtain single cell protein (SCP) in yeast by using biogas slurry as culture medium. The results show that Nectaromyces rattus was the most efficient at producing SCP among the 7 different yeasts studied. Acetic acid was a better pH regulator than hydrochloric acid. After culture with the initial NH₄⁺-N concentration 2,000 mg/L, C/N ratio 6:1, the initial pH 5.50 and rotation speed of 200 rpm, a total cell dry weight of 12.58 g/L with 35.96% protein content was obtained. Nineteen amino acids accounted for 46.85% of cell dry weight, and proline content was as high as 12.0% of the cell dry weight. However, sulfur-containing amino acids, including methionine and cystine, were deficient. Further research should focus on the high cell density culture to increase SCP production.

The effects of rumen nitrogen balance on intake, nutrient digestibility, chewing activity, and milk yield and composition in dairy cows vary with dietary protein sources

The objective was to study the interaction effects of rumen nitrogen balance (RNB) and dietary protein source on feed intake, apparent total-tract digestibility (ATTD), eating and ruminating activity, milk yield (MY), and milk composition in lactating dairy cows. Twenty-four lactating Holstein cows were divided in 4 groups, which were randomly assigned to the dietary treatments included in a replicated 4 × 4 Latin square experimental design that consisted of four 20-d periods, each with 12 d of adaptation to the experimental diets and 8 d of sampling. The dietary treatments followed a 2 × 2 factorial arrangement with 2 main protein sources, faba bean grain (FB) and SoyPass (SP; Beweka Kraftfutterwerk GmbH), offered at 2 dietary RNB levels: RNB0 (RNB of 0 g/kg of dry matter) and RNB- (RNB of -3.2 g/kg of dry matter; i.e., 4 treatments). The composition of concentrate mixtures was adjusted to create diets with the desired RNB levels. Each of the protein sources supplied ≥35% of the total dietary crude protein (CP). Both diets within a protein source had similar forage sources and forage to concentrate ratios and were iso-energetic, but differed in CP concentrations. The main effects of RNB, protein source, and their interactions were tested by PROC MIXED in SAS 9.4 (SAS Institute Inc.). Interaction effects were observed for daily dry matter intake and energy-corrected MY, which were lower for RNB- than RNB0 in diets containing FB (23.5 vs. 24.4 kg dry matter/d; 28.6 vs. 30.6 kg milk/d), but similar in diets containing SP (24.2 vs. 24.3 kg dry matter/d; 31.3 vs. 31.7 kg milk/d). The ATTD of NDF was lower for RNB- compared with RNB0 in the FB (44.9 vs. 49.1 g/100 g) and SP (48.5 vs. 51.9 g/100 g) diets, and greater for the SP than for FB diets. There were interaction effects for ATTD of CP and concentrations of milk urea nitrogen, which were lower for RNB- compared with RNB0 in both, FB (55 vs. 63.1 g/100 g of CP; 5.65 vs. 11.3 mg/dL milk) and SP diets (60 vs. 64.4 g/100 g of CP; 8.74 vs. 13.4 mg/dL milk). However, differences between RNB levels were greater for FB than for SP diets. Furthermore, proportions of milk fatty acids followed the same pattern as that of dietary fatty acids, but biohydrogenation appeared to be greater for RNB- than RNB0 for both protein sources and in FB than in SP diets for both RNB levels. There was an interaction effect on total number of chews per unit of NDF intake, which was greater for RNB- compared with RNB0 for both protein sources. However, the differences between RNB levels were greater in FB than in SP diets. Overall, differences in the animal responses to negative RNB between FB and SP diets suggest a need to better understand the effect of negative RNB levels with different dietary ingredients at similar utilizable CP supply.

The effects of rumen nitrogen balance on nutrient intake, nitrogen partitioning, and microbial protein synthesis in lactating dairy cows offered different dietary protein sources

The aim was to study the effects of rumen N balance (RNB), dietary protein source, and their interaction on feed intake, N partitioning, and rumen microbial crude protein (MCP) synthesis in lactating dairy cows. Twenty-four lactating Holstein cows were included in a replicated 4 × 4 Latin square experimental design comprising four 20-d periods, each with 12 d of adaptation to the experimental diets and 8 d of sampling. The dietary treatments followed a 2 × 2 factorial arrangement (i.e., 4 treatments) with 2 main protein sources [faba bean grain (FB) and SoyPass (SP; Beweka Kraftfutterwerk GmbH, Heilbronn, Germany)] offered at 2 dietary RNB levels each [0 g/kg of dry matter, DM (RNB0) and -3.2 g/kg of DM (RNB-)]. The RNB was calculated as the difference between dietary crude protein (CP) intake and the rumen outflow of undegraded feed CP and MCP and divided by 6.25. Composition of concentrate mixtures was adjusted to create diets with desired RNB levels. Each of these protein sources supplied ≥35% of total dietary CP. Both diets for each protein source were isoenergetic but differed in CP concentrations. The DM intake (kg/d) was lower for RNB- than for RNB0 in diets containing FB, whereas no differences were seen between the RNB levels for SP diets. The RNB- decreased N intake and urinary N excretion but increased milk N use efficiency in both FB and SP diets, with greater differences between the RNB levels for FB diets than for SP diets. Similarly, duodenal MCP synthesis (g/kg of digestible organic matter intake) estimated from purine derivatives in the urine was lower for RNB- than for RNB0 in FB diets but similar between the RNB levels in diets containing SP. Low RNB of approximately -65 g/d (approximately -3.2 g/kg of DM) in diets reduced feed intake, N balance, and performance in high-yielding dairy cows with possibly more pronounced effects in diets containing rapidly degradable protein sources.

Milk Potential of Pantaneira Cows, a Local Breed, at Organic System

Simple Summary

Pantaneira cattle are descendants of the genetic group of crossed European animals and are a breed locally adapted to the Brazilian Pantanal. The use of this breed in organic systems can have benefits for the conservation of the breed and because it is a genetically rustic breed. The aim of this study was to evaluate the performance of Pantaneira primiparous cows under systems with reduced use of concentrate, simulating organic production conditions. There was a reduction in milk yield, but the energy-corrected milk yield and efficiency were not affected. The Pantaneira breed has the genetic potential for the maintenance of competitive production and quality in organic systems.

Abstract

Pantaneiro cattle (Bos taurus taurus) is a breed locally adapted to the Brazilian Pantanal. Local breeds are essential for the quality production of organic systems based on planned grazing practices, because of their results in resilient and productive ecosystems, enhancing biodiversity. This study aimed to evaluate the performance of Pantaneira primiparous cows, and systems with reduced use of concentrate, simulating organic production conditions. Five animals, with an average body weight of 396.2 ± 43.5 kg, were kept in individual continuous grazing regimes and supplemented with different concentrate levels (1.2%, 0.9%, 0.6%, 0.3%, and 0.0% of body weight). The animals were allocated at random in a 5 × 5 Latin square design repeated twice during the study time. The cows had a low dry matter and nutrient intake with a reduction in concentrate level, with improvement in neutral detergent fiber digestibility and a reduction in total nutrient digestibility. No changes were observed in plasma glucose levels or urea excretion, but the plasma urea nitrogen decreased with reductions in concentrate levels. There was a reduction in milk yield, but the energy-corrected milk was not affected by the reduction in concentrate levels; furthermore, the milk yield efficiency was not affected. The milk fat content improved with the reduction in concentrate levels. The Pantaneira breed has the genetic potential for the maintenance of competitive production and quality in organic systems.

Effect of Cassava Residue Substituting for Crushed Maize on In Vitro Ruminal Fermentation Characteristics of Dairy Cows at Mid-Lactation

Simple Summary

Cassava processing and utilization generates many byproducts, such as cassava residue. On one hand, this residue still contains many nutrients like starch, fiber and minerals. On the other hand, it pollutes the environment if not be utilized properly. Lactating dairy cows need to control the body weight for smooth calving, but too much high energy feed material like maize can influence their lipid metabolism. Cassava residue may be a good option for them since it can be used not only as roughage, but also can provide energy for dairy cows. Therefore, this study was conducted to investigate the effect replacing high energy feedstuff crushed maize with cassava residue on in vitro fermentation characteristics of dairy cows in mid-lactation. This may help provide further in vivo tests with data support, which finally, could alleviate feed shortages, reduce environmental pollution and improve economic benefits of dairy farming.

Abstract

This study was conducted to investigate the effect of using cassava residue to replace crushed maize on in vitro fermentation characteristics of dairy cows at mid-lactation and provide guidance for its utilization. The study included seven treatments with four replicates, which used 0% (control, CON), 5%, 10%, 15%, 20%, 25% and 30% cassava residue to replace crushed maize (air-dried matter basis), respectively. A China-patented automated trace gas recording system was used to perform in vitro gas tests; rumen fluids were collected from three dairy cows at mid-lactation. In vitro dry matter digestibility (IVDMD), gas production (GP), pH, ammonia–N (NH₃-N) and microbial protein (MCP) content were analyzed after in vitro incubating for 3, 6, 12, 24 and 48 h, respectively; volatile fatty acid (VFA) content was analyzed after in vitro culturing for 48 h. The results showed that with the increase of substitution ratio of cassava residue, the asymptotic gas production (A) increased quadratically (p < 0.05), cumulative gas production at 48 h (GP₄₈) and the maximum rate of substrate digestion (RmaxS) increased linearly and quadratically (p < 0.05), the time at which the maximum gas production rate is reached (TRmaxG) increases linearly (p < 0.05). In addition, asymptotic gas production in 30% was significantly higher than the other treatments (p < 0.05), RmaxS in 25% and 30% were significantly higher than CON, 5% and 10% (p < 0.05). In addition, with the increase of substitution ratio of cassava residue, when in vitro cultured for 6 h and 12 h, NH₃–N content decreased linearly and quadratically (p < 0.05). NH₃–N content in 30% was significantly lower than the other treatments except 20% and 25% (p < 0.05) after cultivating for 6 h. Moreover, the content of iso-butyrate, iso-valerate, valerate and total VFA (tVFA) decreased linearly and quadratically (p < 0.05), acetate decreased quadratically (p < 0.05) with the increase of substitution ratio of cassava residue. In conclusion, when the cassava residue substitution ratio for crushed maize was 25% or less, there were no negative effects on in vitro ruminal fermentation characteristics of dairy cows at mid-lactation.

Expression of d-psicose-3-epimerase from Clostridium bolteae and Dorea sp. and whole-cell production of d-psicose in Bacillus subtilis

Purpose

d-psicose-3-epimerase (DPEase) catalyses the isomerisation of d-fructose to d-psicose, a rare sugar in nature with unique nutritional and biological functions. An effective industrial-scale method is needed for d-psicose production. Herein, the expression of a neutral and a slightly acidic pH DPEase in Bacillus subtilis was evaluated.

Methods

Two DPEase genes from Clostridium bolteae and Dorea sp. were separately expressed in B. subtilis via plasmid pSTOP1622, and an extra P43 promoter was employed to the expression cassette. The fermentation conditions of the engineered B. subtilis strains were also optimised, to facilitate both cell growth and enzyme production.

Result

The introduction of P43 promoter to the two DPEase genes increased enzyme production by about 20%. Optimisation of fermentation conditions increased DPEase production to 21.90 U/g at 55 °C and 24.01 U/g at 70 °C in B. subtilis expressing C. bolteae or Dorea sp. DPEase, equating to a 94.67% and 369.94% increase, respectively, relative to controls.

Conclusion

Enhanced DPEase production was achieved in B. subtilis expressing C. bolteae or Dorea sp. DPEase genes.

Effects of nitrogen gas flushing in comparison with argon on rumen fermentation characteristics in in vitro studies

In rumen in vitro experiments, although nitrogen gas (N2) flushing has been widely used, its effects on rumen fermentation characteristics are not clearly determined. The present study is the first to evaluate the effects of N2 flushing on rumen fermentation characteristics in in vitro batch culture system by comparing with new applicable non-metabolizable gas: argon (Ar). The rumen fluid was taken from two Korean native heifers followed by incubation for 3, 9, 12, and 24 h with N2 or Ar flushing. As a result, in all incubation time, N2 flushing resulted in higher total gas production than Ar flushing (p < 0.01). Additionally, in N2 flushing group, ammonia nitrogen was increased (p < 0.01). However, volatile fatty acids profiles and pH were not affected by the flushing gases (p > 0.05). In conclusion, the present study demonstrated that N2 flushing can influence the rumen nitrogen metabolism via increased ammonia nitrogen concentration and Ar flushing can be used as a new alternative flushing gas.

Use of different carbohydrate sources associated with urea and implications for in vitro fermentation and rumen microbial populations

Context Alternative feed sources have been investigated as replacements for green forages and cereal grains traditionally used in ruminant feed. We hypothesised that, when replacing sources of true protein with non-protein nitrogen (NPN) in the ruminant diet, the efficiency of utilisation of the NPN may be affected by the source of energy and that different energy resources used as alternatives to maize may improve efficiency and maximise ruminal fermentation characteristics. Aims The objective of this study was to evaluate the effects of diets containing different carbohydrate sources associated with urea on in vitro ruminal fermentation and rumen microbial profile. Methods Four diets based on Tifton 85 Bermuda grass hay (584 g/kg dry matter) were tested as substrates: cornmeal + soybean meal (C + SM, typical diet), cornmeal + urea (C + U), cassava scraping + urea (CS + U), and spineless cactus + urea (SC + U). The experimental design consisted of randomised blocks with four treatments and five blocks. Five adult Nellore cattle with permanent fistula in the rumen were used as inoculum donors. The semi-automatic in vitro gas production technique was used in two experiments. Quantitative real-time PCR was used to monitor the changes in the rumen microbial community. Key results The diets containing C + U and CS + U decreased (P &lt; 0.05) concentrations of isobutyrate, isovalerate, and valerate after 24 h of incubation, and all diets containing urea decreased (P &lt; 0.05) concentrations of isobutyrate, isovalerate and valerate after 96 h and increased (P &lt; 0.05) acetate:propionate ratio. After 96 h of incubation, the diets containing CS + U and SC + U resulted in a lower (P &lt; 0.05) population of Ruminococcus flavefaciens than the C + U diet, and a lower (P &lt; 0.05) population of Streptococcus bovis than the C + SM diet. Conclusions From our results, a diet containing cassava scraping produces more methane per unit of degraded organic matter, which reduces fermentation efficiency. Diets that contain corn with either soybean meal or urea result in greater degradability with lower gas production rates than diets that contain either cassava scrapings or spineless cactus with urea. Diets containing urea as a total substitution for soybean meal alter the production of short-chain fatty acids and reduce the populations of S. bovis and R. flavefaciens. Implications Use of urea to replace soybean meal in the ruminant diet alters ruminal fermentation and rumen microbial population.

Microbial protein formation of different carbohydrates in vitro

The aim of this study was to investigate the microbial protein yield of different pure carbohydrates to contribute to a more precise prediction of the microbial protein formed in the rumen. In a first experiment, sucrose, wheat starch, microcrystalline cellulose and citrus pectin were incubated for 8 and 24 hr in the modified Hohenheim gas test (HGT) system (3 runs × 2 syringes) including gas production, ammonia and short-chain fatty acid concentration measurements. Ammonia values were used for estimation of the microbial protein formation. In a second experiment, the same substrates were incubated for 96 hr in the HGT system (2 runs × 3 syringes) and gas production was measured after 2, 4, 6, 8, 12, 16, 24, 30, 36, 48, 60, 72 and 96 hr of incubation to obtain the fermentation kinetics and the time of half-maximal gas production (t_1/2 ) of the substrates. The substrates differed considerably in their fermentation kinetics, and therefore, comparison on the basis of t_1/2 was chosen as the most meaningful. At t_1/2 , microbial protein yield [g/kg dry matter] was higher for cellulose than for sucrose and pectin and higher for starch than for sucrose. The microbial protein expressed in g/L gas production was higher for starch and cellulose than for sucrose and pectin at t_1/2 . Effects of carbohydrates related to ruminal pH may remain undetected in in vitro trials.