Effects of different forage combinations in total mixed rations on in vitro gas production kinetics, ruminal and milk fatty acid profiles of lactating cows

Effects of dietary supplementation with alkaline mineral complex on in vitro ruminal fermentation and bacterial composition

Introduction

Dairy industry growth faces challenges in China due to inadequate forage, leading to high-concentrate diets and potential rumen issues. Buffering agents, like sodium bicarbonate, play a crucial role in stabilizing rumen pH. Alkaline Mineral Complex (AMC), a liquid additive with a pH of 14, shows promise in supporting dairy cow health and mitigating heat stress through ionization.

Methods

This experiment was aimed to study the effect of adding AMC to total mixed ration (TMR) on in vitro ruminal fermentation and bacterial composition. AMCat 1, 2, 4, and 8 mL/kg was added to the substrate (0.5 g TMR). Nutrient digestibility was measured after 48 h fermentation, and fermentation parameters and microbial composition were measured after 48 h fermentation.

Results and discussion

The results of the experiment indicated that: The different concentrations of AMC showed a significant impact on time taken for gas production to reach 1/2 of the total gas production (HT) parameters (p < 0.05). Linear pH increase occurs at 6 and 24 h with rising AMC concentration (p < 0.05), showing a quadratic trend at 12 h (p < 0.05). The optimal buffering effect on rumen acid-base balance was observed at a 2 mL/kg concentration of AMC. Microbial diversity analysis indicated that there was no significant change in α-diversity with different AMC concentrations (p > 0.05). The microbial level demonstrated no significant difference in species diversity of rumen fluid bacteria among the various AMC concentration treatment groups compared to the control group, further supporting that the advantage of adding AMC in stabilizing the rumen environment without altering the structure of the rumen microbiota. Besides, the addition of AMC significantly increased the concentrations of acetate, propionate, total fatty acids (TVFA), and NH3-N, suggesting that AMC contributed to enhancing the energy and nitrogen utilization efficiency in ruminants. Based on the above detection indicators, we recommend that the most favorable concentration is 2 mL/kg.

Effects of yeast culture on in vitro ruminal fermentation and microbial community of high concentrate diet in sheep

This research aimed to investigate effects of different yeast culture (YC) levels on in vitro fermentation characteristics and bacterial and fungal community under high concentrate diet. A total of 5 groups were included in the experiment: control group without YC (CON), YC1 (0.5% YC proportion of substrate dry matter), YC2 (1%), YC3 (1.5%) and YC4 (2%). After 48 h of fermentation, the incubation fluids and residues were collected to analyze the ruminal fermentation parameters and bacterial and fungal community. Results showed that the ruminal fluid pH of YC2 and YC4 groups was higher (P < 0.05) than that of CON group. Compared with CON group, the microbial protein, propionate and butyrate concentrations and cumulative gas production at 48 h of YC2 group were significantly increased (P < 0.05), whereas an opposite trend of ammonia nitrogen and lactate was observed between two groups. Microbial analysis showed that the Chao1 and Shannon indexes of YC2 group were higher (P < 0.05) than those of CON group. Additionally, YC supplementation significantly decreased (P < 0.05) Succinivibrionaceae_UCG-001, Streptococcus bovis and Neosetophoma relative abundances. An opposite tendency of Aspergillus abundance was found between CON and YC treatments. Compared with CON group, the relative abundances of Prevotella, Succiniclasticum, Butyrivibrio and Megasphaera elsdenii were significantly increased (P < 0.05) in YC2 group, while Apiotrichum and unclassified Clostridiales relative abundances were decreased (P < 0.05). In conclusion, high concentrate substrate supplemented with appropriate YC (1%) can improve ruminal fermentation and regulate bacterial and fungal composition.

Effects of Different Additives on the Chemical Composition, Fermentation Profile, In Vitro and In Situ Digestibility of Paper mulberry Silage

Paper mulberry (Broussonetia papyrifera) plants are served as a local roughage in China, and they are mostly processed as silage for ruminants. This study aimed to explore the effects of different silage additives on the chemical composition, fermentation profile, as well as the in vitro and in situ digestibility of paper mulberry (PM) silage. Four groups consisting of PM silage, three with additives and one without any additives as the control group (CON), were established. The three experimental groups with additives were set up as follows: CON with 5 × 106 CFU per gram of fresh PM weight of lactic acid bacteria (Lactobacillus plantarum) (LAB); CON with 3% fresh PM weight of molasses (MOL) added to the PM silage; and CON with both LAB and MOL added (LM). After 45 days of ensiling at 20 °C, all of the PM treatment groups increased their ash content and decreased their water-soluble carbohydrate content (p < 0.05). Meanwhile, the pH and NH3-N content of the PM silage were lower in the additive treatment groups than in the CON group (p < 0.05). Lactic acid in the LM group was the highest (p < 0.05) among the four groups, and trace amounts of butyric acid was detected only in the CON group. In vitro dry matter digestibility was similar among all groups. Results of the in situ experiment found that the effective digestibility of the PM silage dry matter, as well as the acid detergent fiber digestibility was higher in the LM group than in the CON group (p < 0.05). In conclusion, the addition of LAB, MOL, and their combination can improve PM silage fermentation and improve the in situ digestibility of dry matter and acid detergent fiber; however they do not affect in the vitro digestibility of PM silage.

Compromised Hindgut Microbial Digestion, Rather Than Chemical Digestion in the Foregut, Leads to Decreased Nutrient Digestibility in Pigs Fed Low-Protein Diets

Background: Reduced nutrient digestibility due to low-protein (LP) diets occurring in the foregut or hindgut of pigs remains unclear. Methods: Growing barrows (21.7 ± 1.7 kg) were allotted into LP and high-protein (HP) diet treatments. Ileal digesta and feces were collected for in vitro cross-fermentation and microbial sequencing, and cross-feeding assessed nutrient digestibility. Results: No difference in foregut digesta flora and nutrient digestibility between treatments was observed. LP diet caused decreased total tract digestibility of dry matter (DM), organic matter (OM), gross energy (GE), neutral detergent fiber (NDF), and acid detergent fiber (ADF) compared with the HP diet (p < 0.05). The fermentation broth from LP diet-fed pigs induced less full fermentation digestion of DM, OM, crude protein, and GE than HP broth (p < 0.05). Additionally, LP broth fermentation presented lower fermentation gas and short-chain fatty acids (SCFAs) generation than HP group (p < 0.05). This situation above may be related to decreased abundances of Lachnospiraceae, Eubacterium_eligens_group, Roseburia, and Ruminococcaceae_UCG-009, which can efficiently ferment nutrients to produce SCFA. Conclusions: Change in the flora caused compromise in hindgut microbial fermentation digestion leads to decreased total tract nutrient digestibility in pigs fed an LP diet.

A Combination of Lactic Acid Bacteria and Molasses Improves Fermentation Quality, Chemical Composition, Physicochemical Structure, in vitro Degradability and Rumen Microbiota Colonization of Rice Straw

Aims

This study aims to evaluate the effect of lactic acid bacteria (LAB) and LAB-molasses (LAB + M) combination on the fermentation quality, chemical composition, physicochemical properties, in vitro degradability of rice straw and the characteristics of rumen microbial colonization on rice straw surface.

Methods and Results

There were three pretreatments, including control (not treated, Con), treated with LAB, or LAB + M. The results showed that both LAB and LAB + M treatments altered the physical and chemical structures of rice straw and were revealed by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) spectroscopy, respectively. Moreover, both LAB and LAB + M pretreated rice straw increased the crude protein (CP) content, dry matter (DM) recovery, and in vitro digestibility and decreased the pH value, neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents. The LAB + M pretreated rice straw increased the gas production (GP72) and rumen microbial colonization on the rice straw surface.

Conclusions

It is observed that LAB + M treatment could increase digestibility and the rumen microbial colonization on the rice straw surface. Therefore, LAB + M treatment can provide an alternative strategy to improve the quality of rice straw. Significance and impact of the study: This study provides an optimal pretreatment to improve the rice straw digestibility and rumen microbial colonization.

Effects of Different Parts on the Chemical Composition, Silage Fermentation Profile, In Vitro and In Situ Digestibility of Paper Mulberry

Simple Summary

Paper mulberry (Broussonetia papyrifera, PM) is a potential roughage source widely distributed in Asia, but the chemical composition, silage fermentation, and digestibility are not fully understood. Here, we compared the chemical composition, silage fermentation, and digestibility of leaf, stem, and whole plant of PM to evaluate its feeding value. The result showed that the leaf had lower fiber content and higher protein content than the stem and whole plant. Meanwhile, the stem silage had the lowest pH value and lactate content, while those in the leaf were the highest. The in vitro and in situ digestibility showed the leaf was more digestible. Our study gives the reference of different parts of PM to be used as a feedstuff.

Abstract

Paper mulberry (Broussonetia papyrifera, PM) is high protein but unutilized as a feed source. The study explores the different parts (leaf, stem, and whole plant) of PM chemical composition, silage fermentation, and in vitro and in situ digestibility, aiming to give some guidelines to PM usage as feed. The result showed that the leaf had a higher fresh weight than the stem (p < 0.05). The dry matter contents of the three groups had no differences. The highest crude protein, ether extract, water-soluble carbohydrate, ash, calcium, phosphorus, amino acid contents, and butter capacity were observed in the leaf (p < 0.05). The stem had the highest (p < 0.05) neutral detergent fiber, acid detergent fiber, and lignin contents. After ensiling, the stem silage had the lowest pH value, ammonia nitrate (NH₃-N), lactate, acetate, and propionate (p < 0.05). The leaf silage had the highest pH value (p < 0.05). The lactate, acetate, and propionate in the leaf and whole plant silage had no difference. The butyrate was not detected in all silage. The in vitro and in situ digestibility experiments showed the leaf had the highest digestibility (p < 0.05), which could produce more volatile fatty acids and have a higher effective digestibility. These results allow a greater understanding of PM to be used as a feedstuff.

The Antimethanogenic Nitrocompounds Can be Cleaved into Nitrite by Rumen Microorganisms: A Comparison of Nitroethane, 2-Nitroethanol, and 2-Nitro-1-propanol

A class of aliphatic short chain nitrocompounds have been reported as being capable of CH4 reduction both in vitro and in vivo. However, the laboratory evidence associated with the metabolic fate of nitrocompounds in the rumen has not been well documented. The present study was conducted to compare in vitro degradation and metabolism of nitroethane (NE), 2-nitroethanol (NEOH), and 2-nitro-1-propanol (NPOH) incubated with mixed rumen microorganisms of dairy cows. After 10 mM supplementation of nitrocompounds, a serious of batch cultures were carried out for 120 h under the presence of two substrates differing in the ratio of maize meal to alfalfa hay (HF, 1:4; LF, 4:1). Compared to the control, methane production was reduced by 59% in NPOH and by >97% in both NE and NEOH, and such antimethanogenic effects were more pronounced in the LF than the HF group. Although NE, NEOH, and NPOH addition did not alter total VFA production, the rumen fermentation pattern shifted toward increasing propionate and butyrate and decreasing acetate production. The kinetic disappearance of each nitrocompound was well fitted to the one-compartment model, and the disappearance rate (k, %/h) of NE was 2.6 to 5.2 times greater than those of NEOH and NPOH. Higher intermediates of nitrite occurred in NEOH in comparison with NPOH and NE while ammonia N production was lowest in NEOH. Consequently, a stepwise accumulation of bacterial crude protein (BCP) in response to the nitrocompound addition was observed in both the HF and LF group. In brief, both NE and NEOH in comparison with NPOH presented greater antimethanogenic activity via the shift of rumen fermentation. In addition, the present study provided the first direct evidence that rumen microbes were able to cleave these nitrocompounds into nitrite, and the subsequent metabolism of nitrite into ammonia N may enhance the growth of rumen microbes or promote microbial activities.

In Vitro Fermentation Characteristics for Different Ratios of Soluble to Insoluble Dietary Fiber by Fresh Fecal Microbiota from Growing Pigs

This study was conducted to explore the in vitro fermentation characteristics for different ratios of soluble to insoluble dietary fiber in pig fecal microbiota. The fermentation substrates consisted of inulin and a non-starch polysaccharide mixture and were divided into five groups according to different soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) ratios (SDF 25, 50, 75, and 100%). With the increased SDF ratio, the total gas production increased, and the pH in the substrate decreased as the fermentation proceeded. The concentrations of lactic acid, formic acid, and acetic acid increased in the high SDF ratio group, whereas the concentrations of propionic acid and butyric acid increased in the low SDF ratio group. The genera Clostridium_sensu_stricto_1, Ruminococcaceae_NK4A214_group, Christensenellaceae_R-7_group, and Rikenellaceae_RC9_gut_group were enriched in the high SDF ratio group. Correlation analysis indicated that these differential bacteria had the potential to degrade polysaccharides. These results revealed that high SDF ratios could stimulate the proliferation of fibrolytic bacteria, which in turn degrade fibers to produce organic acids and monosaccharides. Collectively, these findings add to our understanding of the mechanisms responsible for interaction between SDF and intestinal microbiota and provide new ideas for the rational use of dietary fiber.