Ruminal responses, digestibility, and blood parameters of beef cattle fed diets with different oilseeds

It aimed to evaluate the effects of different whole oilseeds in lipid-rich diets on nutrient intake, apparent digestibility, ingestive behavior, and ruminal and blood parameters of steers. A control diet (without oilseed) and four diets containing whole oilseeds (cotton, canola, sunflower, and soybean) were tested. All diets used the whole-plant corn silage at 400 g/kg as roughage. Five diets, being a control diet (without oilseed) and four diets containing whole oilseeds (cotton, canola, sunflower, and soybean), were tested. All diets used the whole-plant corn silage at 400 g/kg as roughage. Five rumen fistulated crossbreed steers, in a 5 × 5 Latin square design were distributed using five periods of 21 days. The steers fed cottonseed and canola diets had lower dry matter intakes (6.6 kg/day). Steers showed higher averages of time in rumination for treatments with sunflower, soybean, and cottonseed (406, 362, and 361 min/day, respectively). There was no treatment effect for the ruminal pH and ammonia (NH₃) variables. There was an effect of the treatment on the volatile fatty acid concentrations. The animals that received soybean showed a higher plasma urea concentration (50.7 mg/dL). Animals fed the control diet showed lower serum cholesterol levels (111.8 mg/dL) than those fed diets containing whole cottonseed, canola, sunflower, and soybean (152.7, 137.1, 146.9, and 138.2 mg/dL, respectively). We recommended using whole soybean or sunflower seeds to formulate lipid-rich diets with 70 g/kg of ether extract for crossbreed steers in the feedlot.

Metagenomic analysis reveals the efficient digestion mechanism of corn stover in Angus bull rumen: Microbial community succession, CAZyme composition and functional gene expression

Ruminant rumen is a biological fermentation system that can efficiently degrade lignocellulosic biomass. The knowledge about mechanisms of efficient lignocellulose degradation with rumen microorganisms is still limited. In this study, composition and succession of bacteria and fungi, carbohydrate-active enzymes (CAZymes), and functional genes involved in hydrolysis and acidogenesis were revealed during fermentation in Angus bull rumen via metagenomic sequencing. Results showed that degradation efficiency of hemicellulose and cellulose reached 61.2% and 50.4% at 72 h fermentation, respectively. Main bacterial genera were composed of Prevotella, Butyrivibrio, Ruminococcus, Eubacterium, and Fibrobacter, and main fungal genera were composed of Piromyces, Neocallimastix, Anaeromyces, Aspergillus, and Orpinomyces. Principal coordinates analysis indicated that community structure of bacteria and fungi dynamically changed during 72 h fermentation. Bacterial networks with higher complexity had stronger stability than fungal networks. Most CAZyme families showed a significant decrease trend after 48 h fermentation. Functional genes related to hydrolysis decreased at 72 h, while functional genes involved in acidogenesis did not change significantly. These findings provide a in-depth understanding of mechanisms of lignocellulose degradation in Angus bull rumen, and may guide the construction and enrichment of rumen microorganisms in anaerobic fermentation of waste biomass.

Effect of propionate, monensin, and saccharomyces cerevisiae or their combination on production and rumen fermentation of holstein steers

This study aimed to evaluate the effects of calcium propionate (PrCa), PrCa + monensin sodium (PrCa + Mon), and PrCa + Saccharomyces cerevisiae (PrCa + Sc) on the productive performance of Holstein steers. Twenty-four Holstein steers (270.0 ± 25.85 kg) were distributed individually into four treatments of six replicates. The treatments were control (no additives), PrCa (10 g/kg), PrCa + Mon (10 g/kg + 30 mg/kg), and PrCa + Sc (10 g/kg + 12.8 × 10⁹ cfu). The steers were fed for 43 days, and afterwards, nutrient intake and digestibility as well as volatile fatty acids were determined, while the weight gained, feed efficiency, and CH₄ production were calculated. Diet of PrCa + Sc had the highest (P < 0.0001) acid detergent fiber intake and propionate acid as well as the nutrient digestibility, with lowest (P < 0.0001) rumen acetic acid, methane, and protozoa concentration versus other diets. In conclusion, dietary inclusion of PrCa + Sc (10 g/kg + 12.8 × 10⁹ cfu) improved nutrient digestibility, rumen fermentation, and reduced methane emission, thereby enhancing the possibility of ecofriendly ruminant farming.

Effects of the addition of non-fibre carbohydrates with different rumen degradation rates in dairy cow high-forage diets using the Rumen Simulation Technique

Nutrient synchronisation of protein and carbohydrates is a promising practice to improve ruminal nutrient utilisation. However, dietary sources supplying these nutrients can vary in ruminal nutrient availability due to differing degradation rates, therefore potentially affecting utilisation of nitrogen (N). The effects of the addition of non-fibre carbohydrates (NFCs) with different rumen degradation rates in high-forage diets on ruminal fermentation, efficiency and microbial flow were investigated in vitro using the Rumen Simulation Technique (RUSITEC). Four diets were tested: control with 100% ryegrass silage (GRS) and substitution of 20% on a DM basis of ryegrass silage with corn grain (CORN), processed corn (OZ) or sucrose (SUC). The four diets were assigned to 16 vessels in two sets of RUSITEC apparatuses in a randomised block design over a 17 d experimental trial; 10 d consisted of adaptation and 7 d for sample collection. Rumen fluid was collected from four rumen-cannulated dry Holstein-Friesian dairy cows and was treated without mixing. Then, rumen fluid from each cow was used to inoculate four vessels, and diet treatments were randomly allocated to each one. This was repeated for all cows resulting in 16 vessels. The inclusion of SUC in ryegrass silage diets improved DM and organic matter digestibility. The only diet to significantly lower ammonia-N concentration compared with GRS was SUC. The outflows of non-ammonia-N, microbial-N, and efficiency of microbial protein synthesis were not affected by diet type. However, the efficiency of nitrogen utilisation was improved by SUC compared with GRS. This indicates that the inclusion of an energy source with a high rumen degradation rate in high-forage diets improves rumen fermentation, digestibility, and N utilisation. Specifically, this effect was observed for the more readily available energy source, SUC, compared with the more slowly degradable NFC sources, CORN and OZ.

Yeast-fermented cassava as a protein source in cattle feed: systematic review and meta-analysis

The present study evaluated the effect of the inclusion of cassava fermented with Saccharomyces cerevisiae yeasts on performance, feed intake, nutrient digestibility, rumen microorganisms and ruminal fermentation of cattle through a systematic review and meta-analysis. The effects of yeast-fermented cassava (YFC) in the diet of cattle were evaluated using the mean difference as a measure of the effect size, considering a confidence interval of 95%. Subgroup and meta-regression analysis were performed to investigate the origin of heterogeneity. The database included eight experiments. Three studies were related to dairy heifers, three related to dairy cow and the remaining two studies were associated to beef heifers. The inclusion of YFC in the bovine diet increased the dry matter intake %BW (P < 0.01) and nutrient digestibility (P < 0.05). We observed an increase in mean ruminal pH (P < 0.01), volatile fatty acid (P < 0.01) and propionic acid concentration (P < 0.01). There was a significant increase in the population of bacteria (P < 0.01) and fungi (P < 0.01), and a reduction in the protozoan count in the rumen fluid (P < 0.01) in the animals fed with YFC. Lactating cows fed YFC produced 1.02 kg/day more (P < 0.01) milk than non-supplemented cows. In addition, there was an increase of 7.4% in the fat (P = 0.03), 6.3% in the protein (P < 0.01) and 2.8% in lactose (P = 0.02) of milk of cows supplemented with YFC. The results of the present meta-analysis showed that the total or partial inclusion of YFC in cattle concentrate improves fermentation and rumen efficiency, dry matter intake, nutrient digestibility, milk yield, and milk composition.

Production, purification, characterization and application of two novel endoglucanases from buffalo rumen metagenome

BACKGROUND

Lignocellulose biomass is the most abundant and renewable material in nature. The objectives of this study were to characterize two endoglucanases TrepCel3 and TrepCel4, and determine the effect of the combination of them (1.2 mg TrepCel3, 0.8 mg TrepCel4) on in vitro rumen fermentation characteristics. In this study, three nature lignocellulosic substrates (rice straw, RS; wheat straw, WS; leymus chinensis, LC) were evaluated for their in vitro digestibility, gas, NH3-N and volatile fatty acid (VFA) production, and microbial protein (MCP) synthesis by adding enzymatic combination.

METHODS

Two endoglucanases' genes were successfully expressed in Escherichia coli (E. coli) BL21 (DE3), and enzymatic characteristics were further characterized. The combination of TrepCel3 and TrepCel4 was incubated with lignocellulosic substrates to evaluate its hydrolysis ability.

RESULTS

The maximum enzymatic activity of TrepCel3 was determined at pH 5.0 and 40 °C, while TrepCel4 was at pH 6.0 and 50 °C. They were stable over the temperature range of 30 to 60 °C, and active within the pH range of 4.0 to 9.0. The TrepCel3 and TrepCel4 had the highest activity in lichenan 436.9 ± 8.30 and 377.6 ± 6.80 U/mg, respectively. The combination of TrepCel3 and TrepCel4 exhibited the highest efficiency at the ratio of 60:40. Compared to maximum hydrolysis of TrepCel3 or TrepCel4 separately, this combination was shown to have a superior ability to maximize the saccharification yield from lignocellulosic substrates up to 188.4% for RS, 236.7% for wheat straw WS, 222.4% for LC and 131.1% for sugar beet pulp (SBP). Supplemental this combination enhanced the dry matter digestion (DMD), gas, NH3-N and VFA production, and MCP synthesis during in vitro rumen fermentation.

CONCLUSIONS

The TrepCel3 and TrepCel4 exhibited the synergistic relationship (60:40) and significantly increased the saccharification yield of lignocellulosic substrates. The combination of them stimulated in vitro rumen fermentation of lignocellulosic substrates. This combination has the potential to be a feed additive to improve agricultural residues utilization in ruminants. If possible, in the future, experiments in vivo should be carried out to fully evaluate its effect.

Effects of different proportions of stevia stalk on nutrient utilization and rumen fermentation in ruminal fluid derived from sheep

Background

Stevia straw is a byproduct of sugar crop stevia. It is a good feed material because of richness in nutrients and active substances (steviosides and flavonoids). However, due to improper utilization such as piling, burning and so on, it became a large amount of wasted straw resources and lead to environmental pollution.

Methods

We added 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0% and 1.5% of stevia stalk to study the effects of different stevia stalk concentrations on nutrient utilization and rumen fermentation in sheep (based on sheep diet). In vitro fermentation method was used, with 17 repetitions for each treatment. All fermentation substrate based on sheep diet with different stevia stalk concentrations were fermented for 2 h, 6 h, 12 h, 24 h and 48 h, then the gas production, dry matter degradability (DMD), crude protein degradability (CPD), neutral detergent fiber degradability (NDFD), acid detergent fiber degradability (ADFD), pH, ammonia nitrogen (NH₃-N) and volatile fatty acids (VFAs) were determined.

Results

The results showed that at different fermentation time, the change trend of gas production in each teatment was basically same, but the maximum occurred in 1.0% treatment at 48 h. The DMD, CPD, NDFD and ADFD of sheep diets increased with fermentation time increasing, especially the CPD_48h, NDFD_48h and ADFD_48h of diets in 0.8%, 1.0% and 1.5% treatments were significantly higher than those in control (P < 0.05). The pH of fermentation substrate in each treatment remained within the normal range of 6.21∼7.25. NH₃-N_24h-48hin 0.8%, 1.0% and 1.5% treatments were higher than that in control. At 6 h-12 h, the total acid content of 0.8% and 1.0% treatments were significantly higher than those of other treatments (P < 0.05), it reached the highest in 1.0% treatment. According to overall evaluation, effect ranking of stevia stalk on sheep nutrient utilization was as follows: 1.0% >0.8% >1.5% >0.4% >0.6% >0.2%. Overall, 1.0% stevia stalk could promote nutrient degradation and sheep rumen fermentation.

Fermentation of increasing ratios of grain starch and straw fiber: effects on hydrogen allocation and methanogenesis through in vitro ruminal batch culture

Grain starch has a faster rate of rumen fermentation than straw fiber and causes a rapid increase in ruminal molecular hydrogen (H₂) partial pressure, which may promote other H₂ sinks to compete H₂ away from methanogenesis. The study was designed to investigate the effects of increasing ratios of grain starch to straw fiber on hydrogen allocation and methanogenesis through in vitro ruminal batch incubation. Corn grain and corn straw were employed as starch and fiber source respectively. Seven treatments were the ratios of corn grain to corn straw (RGS) being 0:6, 1:5, 2:4, 3:3, 4:2, 5:1, and 6:0. Elevating RGS increased dry matter (DM) degradation and decreased methane (CH₄) and hydrogen gas (gH₂) production relative to DM degraded. Elevating RGS increased volatile fatty acid (VFA) concentration, propionate molar percentage and microbial protein (MCP) concentration, decreased acetate molar percentage, acetate to propionate ratio and estimated net metabolic hydrogen ([H]) production relative to DM degraded. Elevating RGS decreased the molar percentage of [H] utilized for CH₄ and gH₂ production. In summary, increasing ratios of grain starch to straw fiber altered rumen fermentation pathway from acetate to propionate production, reduced the efficiency of [H] production with the enhancement of MCP synthesis, and led to a reduction in the efficiency of CH₄ and gH₂ production.

Cassava pulp added to fermented total mixed rations increased tropical sheep's nutrient utilization, rumen ecology, and microbial protein synthesis

Objective

The price of animal production will be affected by the significant increase in feed costs. The objective of this research was to investigate the impact of adding waste cassava pulp to fermented total mixed ration (FTMR) on nutrient utilization, rumen ecology, and microbial protein synthesis in tropical sheep.

Materials and Methods

A 3 × 3 replicated Latin square design was used to randomly arrange nine crossbreed lambs (Santa Inês × Dorper) with an initial body weight (BW) of 18.7 ± 1.6 kg (mean ± SD). During a 21-day trial, the animal was offered a random selection of concentrate diets and rice straw (control), total mixed ration (TMR), or FTMR. During the investigation, data on nutrition utilization, rumen ecology, and microbial protein synthesis were analyzed using analysis of variance.

Results

The finding shows that FTMR had significantly higher dry matter (DM) intake and DM intake per BW than either TMR or control (p < 0.05). Lamb fed on FTMR had significantly higher DM, organic matter protein, crude protein, and neutral detergent fiber digestion than those on control or TMR (p < 0.05). Rumen pH values for all treatments ranged from 6.68 to 6.73, with no significant differences. Growing lambs fed FTMR had greater rumen total volatile fatty acid and propionic acid concentrations than those given TMR and the control (p < 0.05). Protozoa were not different across the FTMR groups, although total bacterial and fungal zoospores were increased. In addition, when lambs were fed FTMR containing cassava pulp, ruminal microbial protein synthesis was significantly increased.

Conclusion

It could indicate that feeding growing lambs with FTMR could improve nutrient utilization, ruminal fermentation, and microbial protein synthesis. However, studies on the effects of FTMR on sheep performance, meat quality, and milk quality are necessary.

Mulberry flavonoids modulate rumen bacteria to alter fermentation kinetics in water buffalo

Mulberry flavonoids can modulate the composition of rumen microbiota in ruminants to improve nutrient digestibility, owing to their strong biological activities. This study aimed to explore the effect of mulberry leaf flavonoids (MLF) on rumen bacteria, fermentation kinetics, and metagenomic functional profile in water buffalo. Forty buffaloes (4 ± 1 lactations) with almost same body weight (av. 600 ± 50 Kg) and days in milk (90 ± 20 d) were randomly allocated to four treatments having different levels of MLF: 0 g/d (control), 15 g/d (MLF15), 30 g/d (MLF30), and 45 g/d (MLF45) supplemented in a basal diet. After 35 days of supplementation, rumen contents were collected to determine rumen fermentation parameters. The 16S rRNA gene sequencing was performed to elucidate rumen bacteria composition. The obtained taxonomic data were analyzed to explore the rumen bacteriome and predict the associated gene functions and metabolic pathways. Results demonstrated a linear increase (p < 0.01) in rumen acetate, propionate, and total VFAs in the MLF45 group as compared to control. No effect of treatment was observed on rumen pH and butyrate contents. Acetate to propionate ratio in the MLF45 group linearly and quadratically decreased (p = 0.001) as compared to MLF15 and control groups. Similarly, MLF45 linearly increased (p < 0.05) the microbial protein (MCP) and NH₃-N as compared to other treatments. Treatment adversely affected (p < 0.01) almost all alpha diversity parameters of rumen bacteria except Simpson index. MLF promoted the abundance of Proteobacteria while reducing the relative abundances of Actinobacteria, Acidobacteria, Chloroflexi, and Patescibacteria. The MLF supplementation tended to substantially reduce (0.05 < p < 0.1) the abundance of Actinobacteria, and Patescibacteria while completely eliminating Acidobacteria (p = 0.029), Chloroflexi (p = 0.059), and Gemmatimonadetes (p = 0.03) indicating the negative effect of flavonoids on the growth of these bacteria. However, MLF45 tended to substantially increase (p = 0.07) the abundance (~21.5%) of Acetobacter. The MLF treatment exhibited negative effect on five genera by significantly reducing (Sphingomonas) or eliminating (Arthobactor, unclassified_c__Actinobacteria, norank_c__Subgroup_6, norank_o__Saccharimonadales, and Nocardioides) them from the rumen microbiota. Pearson correlation analysis revealed 3, 5 and 23 positive correlations of rumen bacteria with milk yield, rumen fermentation and serum antioxidant parameters, respectively. A positive correlation of MCP was observed with three bacterial genera (Acetobacter, Enterobacter, and Klebsiella). The relative abundance of Pseudobutyrivibrio and Empedobacter also showed a positive correlation with the ruminal acetate and propionate. The present study indicated 45 g/d as an appropriate dose of MLF which modulated rumen bacteria and its functional profile in water buffalo.

Feed tossing behaviour of Holstein cows: evaluation of physiological stress state and rumen fermentation function

Background

Abnormal or stereotyped behaviours in dairy cows are common in large-scale indoor farms and are usually accompanied by high physiological stress levels. Feed tossing is an abnormal behaviour commonly seen in cows while being fed, making farm management difficult. However, the reasons behind this behaviour have not been sufficiently reported. The objective of this study was to explore the changes in rumen fermentation, serum indicators, inflammatory conditions and the performance of cows with feed tossing behaviour. Holstein cows with similar lactation stages in the same barn were subjected to behaviour observations two times per day for 21 consecutive days. Ten cows with feed tossing behaviour (FT) and ten cows without abnormal behaviours (CON) were selected for further sampling. Plasma samples, rumen fluid, milk yield data of cows, and an indoor environment temperature-humidity index (THI) were collected.

Results

There was no significant difference in average daily milk yield during the observation period between feed-tossing cows (n = 68) and the other cows (n = 112). The number of cows showing FT behaviour had a moderately strong negative linear correlation with the THI of the environment. Compared to the CON cows, the FT cows had higher cortisol, norepinephrine and urea nitrogen levels in plasma, as well as higher plasma levels of inflammatory indicators, including total protein, lactate dehydrogenase, albumin, aspartate aminotransferase levels, and the ratio of aspartate aminotransferase to alanine aminotransferase. The FT cows had no significant variations from the CON cows regarding their rumen fermentation indicators, such as pH, ammonia nitrogen, and volatile fatty acids. In addition, 16S rRNA analysis revealed that there might be no clear association between the diversity and abundance of rumen bacteria and feed tossing behaviour.

Conclusions

Our findings suggested that cows might have suffered from high levels of physiological stress and immune state for a long period when they exhibited FT behaviour. The environmental THI could affect the FT behaviour of cows; as the THI increases, the willingness of cows to throw decreases. This work provided the first evidence that feed tossing might be a response associated with high levels of physiological stress and immune. It also explored our insights into a commonly observed behavioural response to cow welfare traits.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03469-0.

Defatted silkworm pupae meal as an alternative protein source for cattle

Silkworm pupae meal (SWP) is a protein-rich by-product of the silk reeling industry, available in a significant quantity. However, there has been little and insignificant research into the use of SWP in ruminants to date. In this view, the present study was conducted in two phases to evaluate the effect of different inclusion levels of defatted silkworm pupae meal (DSWP) on rumen fermentation, microbial protein synthesis and nutrient utilisation in cattle fed on finger millet straw (FMS)-based diet. Four isonitrogenous concentrate mixtures (CM) were prepared with DSWP replacing soybean meal (SBM) protein at 0 (T0), 10 (T1), 20 (T2) and 30% (T3). In phase I, a rumen fermentation experiment was conducted in a 4 × 4 Latin square design using four crossbred steers to study the effect of different levels of DSWP on rumen fermentation. No significant difference (P > 0.05) was observed in rumen fermentation parameters such as pH, ammonia nitrogen (NH₃-N) and total volatile fatty acids (VFA) among the experimental groups. In phase II, the digestibility trial was conducted in 20 crossbred cattle (311.2 ± 4.81 kg), which were divided into four experimental groups of five animals each in a completely randomised design to study the effect of different rations (T0, T1, T2, T3) on microbial protein synthesis and nutrient utilisation. The intake and digestibility of nutrients, excretion of urinary purine derivatives and microbial protein synthesis were not significantly different among the experimental groups. In addition, feeding DSWP revealed no significant (P > 0.05) change in the blood biochemical parameters of animals. Furthermore, at the same price as SBM, DSWP provides two units more crude protein. Therefore, the results of the present study indicated that DSWP can be incorporated into the ration of cattle up to 30% by replacing SBM without affecting rumen fermentation pattern and nutrient utilisation.

A comparison of average daily gain, apparent digestibilities, energy balance, rumen fermentation parameters, and serum metabolites between yaks (Bos grunniens) and Qaidam cattle (Bos taurus) consuming diets differing in energy level

Yaks (Bos grunniens), indigenous to the harsh Qinghai-Tibetan Plateau, are well adapted to the severe conditions, and graze natural pasture without supplements all year round. Qaidam cattle (Bos taurus), introduced to the Qinghai-Tibetan Plateau 1,700 years ago, are raised at a lower altitude than yaks, provided with shelter at night and offered supplements in winter. Based on their different backgrounds, we hypothesized that yaks have lower energy requirements for maintenance than cattle. To test this hypothesis, we measured average daily gain (ADG), apparent digestibilities, energy balance, rumen fermentation parameters, and serum metabolites in growing yaks and cattle offered diets differing in metabolizable energy (ME) levels (6.62, 8.02, 9.42 and 10.80 MJ/kg), but with the same crude protein concentration. Six castrated yaks (155 ± 5.8 kg) and 6 castrated Qaidam cattle (154 ± 8.0 kg), all 2.5 years old, were used in 2 concurrent 4 × 4 Latin square designs. Neutral and acid detergent fiber digestibilities were greater (P < 0.05) in yaks than in cattle, and decreased linearly (P < 0.05) with increasing dietary energy level; whereas, digestibilities of dry matter, organic matter, crude protein and ether extract increased (P < 0.05) linearly with increasing energy level. The ADG was greater (P < 0.001) in yaks than in cattle, and increased (P < 0.05) linearly with increasing energy levels. From the regressions of ADG on ME intake, the estimated ME requirement for maintenance was lower (P < 0.05) in yaks than in cattle (0.43 vs. 0.57 MJ/kg BW^0.75). The ratios of digestible energy (DE):gross energy and ME:DE were higher (P < 0.05) in yaks than in cattle, and increased (P < 0.05) linearly with increasing dietary energy level. Ruminal pH decreased (P < 0.05), whereas concentrations of total volatile fatty acids (VFAs) and ammonia increased (P < 0.01) with increasing dietary energy level, and all were greater (P < 0.05) in yaks than in cattle. Concentrations of ruminal acetate and iso-VFAs were greater (P < 0.05), whereas propionate was lower (P < 0.05) in yaks than in cattle; acetate decreased (P < 0.001), whereas butyrate and propionate increased (P < 0.001) linearly with increasing dietary energy level. Serum concentrations of β-hydroxybutyrate were lower (interaction, P < 0.001) in yaks than in cattle fed diets of 9.42 and 10.80 MJ/kg, whereas non-esterified fatty acids were greater (interaction, P < 0.01) in yaks than in cattle fed diets of 6.62 and 8.02 MJ/kg. Concentrations of serum leptin and growth hormone were greater in yaks than in cattle and serum insulin and growth hormone increased (P < 0.01) linearly with increasing dietary energy level. Our hypothesis that yaks have lower energy requirements for maintenance than cattle was supported. This lower requirement confers an advantage to yaks over Qaidam cattle in consuming low energy diets during the long winter on the Qinghai-Tibetan Plateau.

Lactational performance, feeding behavior, ruminal fermentation and nutrient digestibility in dairy cows fed whole-plant faba bean silage-based diet with fibrolytic enzyme

Whole-plant faba bean silage has a high content in indigestible fiber. Improvement of fiber digestibility of faba bean silage would benefit animal production. However, there is no study on pretreating fibrolytic enzyme in whole-plant faba bean silage-based diet for dairy cows on animal performance. The objectives of this study were to evaluate the effects of pretreating whole-plant faba bean silage-baseddiet with fibrolytic enzyme (a mixture of xylanase and cellulase; AB Vista, UK) derived from Trichoderma reesei(FETR) on lactational performance, digestibility, ruminal fermentation characteristics, and feeding behavior of dairy cows. The animal trial was conducted using eight lactating Holstein cows (BW = 710 ± 44 kg and Days in Milk (DIM) = 121 ± 17 days) with four levels of FETR (0, 0.5, 0.75, and 1.0 mL of FETR/kg DM of silage) in a replicated Latin square design. These enzyme treatments were selected based on the previous in situ and in vitro findings that showed positive responses to the whole-plant faba bean silage. The enzyme treatments were directly applied on the silage prior to mixing process. The total mixed rations contained 31% of faba bean silage, 14% of grass hay, 3.5% of straw, 30% of barley and corn grain and 21.5% of concentrate. There was no significant difference of applying FETR on nutrient intake (P > 0.05) except for CP intake, which was reduced in FETR group compared to control (P < 0.01, 4.4 vs 4.54 kg/d). There was a linear effect found in NDF digestibility when treated with FETR, where maximum improvement was achieved with 0.5 mL of FETR application. The milk fat yield, percentage of milk fat and fat-corrected milk were linearly affected by the increasing level of enzyme. The cows fed a diet supplemented with enzymes tended to have a lower milk fat. Feed efficiency linearly responded to incremental levels of FETR. There was no enzyme effect on feeding behavior and nitrogen balance and utilization. Results from this study indicated that supplementing fibrolytic enzyme on whole-plant faba bean silage diets for dairy cows improved lactational performance, intake and digestibility with 0.5 mL of FETR application. However, adding higher enzyme level resulted in negative effects on animal performance.

Microbial colonisation of tannin-rich tropical plants: Interplay between degradability, methane production and tannin disappearance in the rumen

Condensed tannins in plants are found free and attached to protein and fibre but it is not known whether these fractions influence rumen degradation and microbial colonisation. This study explored the rumen degradation of tropical tannin-rich plants and the relationship between the disappearance of free and bound condensed tannin fractions and microbial communities colonising plant particles using in situ and in vitro experiments. Leaves from Calliandra calothyrsus, Gliricidia sepium, and Leucaena leucocephala, pods from Acacia nilotica and the leaves of two agricultural by-products: Manihot esculenta and Musa spp. were incubated in situ in the rumen of three dairy cows to determine their degradability for up to 96 h. Tannin disappearance was determined at 24 h of incubation, and adherent microbial communities were examined at 3 and 12 h of incubation using a metataxonomic approach. An in vitro approach was also used to assess the effects of these plants on rumen fermentation parameters. All plants contained more than 100 g/kg of condensed tannins with a large proportion (32-61%) bound to proteins. Calliandra calothyrsus had the highest concentration of condensed tannins at 361 g/kg, whereas Acacia nilotica was particularly rich in hydrolysable tannins (350 g/kg). Free condensed tannins from all plants completely disappeared after 24-h incubation in the rumen. Disappearance of protein-bound condensed tannins was variable with values ranging from 93% for Gliricidia sepium to 21% for Acacia nilotica. In contrast, fibre-bound condensed tannin disappearance averaged ∼ 82% and did not vary between plants. Disappearance of bound fractions of condensed tannins was not associated with the degradability of plant fractions. The presence of tannins interfered with the microbial colonisation of plants. Each plant had distinct bacterial and archaeal communities after 3 and 12 h of incubation in the rumen and distinct protozoal communities at 3 h. Adherent communities in tannin-rich plants had a lower relative abundance of fibrolytic microbes, notably Fibrobacter spp. whereas, archaea diversity was reduced in high-tannin-containing Calliandra calothyrsus and Acacia nilotica at 12 h of incubation. Concurrently, in vitro methane production was lower for Calliandra calothyrsus, Acacia nilotica and Leucaena leucocephala although for the latter total volatile fatty acids production was not affected and was similar to control. Here, we show that the total amount of hydrolysable and condensed tannins contained in a plant govern the interaction with rumen microbes affecting degradability and fermentation. The effect of protein- and fibre-bound condensed tannins on degradability is less important.

Whole-plant corn silage improves rumen fermentation and growth performance of beef cattle by altering rumen microbiota

In recent years, whole-plant corn silage has been widely used in China. Roughage is an important source of nutrition for ruminants and has an important effect on rumen microbiota, which plays an important role in animal growth performance and feed digestion. To better understand the effects of different silages on rumen microbiota, the effects of whole-plant corn silage or corn straw silage on growth performance, rumen fermentation products, and rumen microbiota of Simmental hybrid cattle were studied. Sixty healthy Simmental hybrid cattle were randomly divided into 2 groups with 6 replicates in each group and 5 cattle in each replicate. They were fed with whole-plant corn silage (WS) diet and corn straw silage (CS) diet respectively. Compared with corn straw silage, whole-plant corn silage significantly increased daily gain and decreased the feed intake-to-weight gain ratio (F/G) of beef cattle. Whole-plant corn silage also decreased the acetic acid in the rumen and the acetate-to-propionate ratio (A/P) compared with corn straw silage. On the genus level, the relative abundance of Prevotella_1 was significantly increased while the relative abundance of Succinivibrionaceae_UCG-002 was decreased in cattle fed whole-plant corn silage compared with those fed corn straw silage. Prevotella_1 was positively correlated with acetic acid and A/P. Succinivibrionaceae_UCG-002 was positively correlated with propionic acid and butyric acid, and negatively correlated with pH. Feeding whole-plant corn silage improved amino acid metabolism, nucleotide metabolism, and carbohydrate metabolism. Correlation analysis between rumen microbiota and metabolic pathways showed that Succinivibrionaceae_UCG-002 was negatively correlated with glycan biosynthesis and metabolism, metabolism of co-factors and vitamins, nucleotide metabolism, and translation while Prevotellaceae_UCG-003 was positively correlated with amino acid metabolism, carbohydrate metabolism, energy metabolism, genetic information processing, lipid metabolism, membrane transport, metabolism of cofactors and vitamins, nucleotide metabolism, replication and repair, and translation. Ruminococcus_2 was positively correlated with amino acid metabolism and carbohydrate metabolism. Feeding whole-plant corn silage can improve the growth performance and rumen fermentation of beef cattle by altering rumen microbiota and regulating the metabolism of amino acids, carbohydrates, and nucleotides. KEY POINTS: • Feeding whole-plant corn silage could decrease the F/G of beef cattle • Feeding whole-plant corn silage improves rumen fermentation in beef cattle • Growth performance of beef cattle is related to rumen microbiota and metabolism.

Effects of folic acid and cobalt sulphate supplementation on growth performance, nutrient digestion, rumen fermentation and blood metabolites in Holstein calves

To investigate the influences of cobalt (Co) and folic acid (FA) on growth performance and rumen fermentation, Holstein male calves (n 40) were randomly assigned to four groups according to their body weights. Cobalt sulphate at 0 or 0·11 mg Co/kg DM and FA at 0 or 7·2 mg/kg DM were used in a 2 × 2 factorial design. Average daily gain was elevated with FA or Co supplementation, but the elevation was greater for supplementing Co in diets without FA than with FA. Supplementing FA or Co increased DM intake and total-tract nutrient digestibility. Rumen pH was unaltered with FA but reduced with Co supplementation. Concentration of rumen total volatile fatty acids was elevated with FA or Co inclusion. Acetate percentage and acetate to propionate ratio were elevated with FA inclusion. Supplementing Co decreased acetate percentage and increased propionate percentage. Activities of xylanase and α-amylase and populations of total bacteria, fungi, protozoa, Ruminococcus albus, Fibrobacter succinogenes and Prevotella ruminicola increased with FA or Co inclusion. Activities of carboxymethyl-cellulase and pectinase increased with FA inclusion and population of methanogens decreased with Co addition. Blood folates increased and homocysteine decreased with FA inclusion. Blood glucose and vitamin B₁₂ increased with Co addition. The data suggested that supplementing 0·11 mg Co/kg DM in diets containing 0·09 mg Co/kg DM increased growth performance and nutrient digestibility but had no improvement on the effects of FA addition in calves.

Dietary inclusion of restaurant food waste effects on nutrient digestibility, milk yield and its composition, blood metabolites of lactating Zaraibi goats, and their offspring performance

This study aimed to evaluate the effects of rations containing restaurant food waste (RFW) on nutrient digestibility, milk yield and its composition, and some blood parameters of lactating Zaraibi goats. In the last month of pregnancy, 30 goats (32.8 + 0.91 kg body weight and aged 3-4 years) were chosen and divided into three similar groups (10 goats per group). Each group was randomly assigned to be fed one of the experimental rations. The control group (R1) fed on a ration comprising concentrate feed mixture (CFM1) and berseem as a fresh roughage whereas the second (R2) and the third groups (R3) fed on CFM partially substituted by 15 and 30% of RFW (CFM2 and CFM3, respectively). Nutrient digestibility and feeding values were improved with R3 goats, which had the highest level of RFW (30%) versus R2 and R1 goats. The total volatile fatty acid (TVFA) concentration in the in-rumen liquor was elevated by increasing the level of RFW up to 30% in CFM3 of R3 goats. Actual daily milk yields were significantly (P < 0.05) higher (1269.30 g/h/d) for R3 goats versus R1 and R2 (1037.57 and 1180.70 g/h/d, respectively). The inclusion of RFW in rations had a significant effect on the yield of milk constituents, without significant different among experimental rations regarding some blood constituents and offspring performance. Economic feed efficiency (relative feed cost and relative daily profit) was improved by including RFW in the CFM. Therefore, it can be concluded that the inclusion of up to 30% RFW improved productive performance and economic efficiency in lactating Zaraibi goat rations.

De-oiled palm kernel cake for stall-fed buffaloes: effect on milk constituents, nutrient digestibility, biochemical parameters, and rumen fermentation

Palm kernel cake, the main by-product of the palm kernel oil extraction process, is a highly available and low-priced agro-industrial by-product. However, several concerns exist to arriving at a safe inclusion level, especially for buffaloes. Two experiments were conducted to evaluate the effects of feeding de-oiled palm kernel cake (DPKC) to tropical buffaloes. In trial I, four fistulated Murrah buffaloes arranged in a 4 × 4 Latin square design were fed diets containing DPKC inclusions at 0, 15, 30, and 45% levels of compound feed to study their effects on rumen fermentation parameters. Trial II involves feeding twelve lactating buffaloes with DPKC inclusion levels at 0 or 15% of the compound feed to evaluate the effect of DPKC on the nutrient digestibility, serum biochemical constituents, rumen fermentation patterns, and lactation profile. The DPKC diets did not affect rumen pH, TCA-ppt nitrogen, and TVFA proportion; nevertheless, the NH₃-N data revealed a decreased trend (P = 0.076). The acetate fraction decreased linearly (P < 0.05) with increased DPKC diets. Replacing the conventional protein sources with DPKC at a 15% level did not influence the nutrient intake and digestibility coefficients. No significant effects were observed for serum biochemical and mineral profiles of the lactating buffaloes fed the DPKC diet. Neither milk yield nor milk constituents (SNF, total solids, density, lactose, protein) were altered with the diets fed, except for milk fat%, which tended to increase (P = 0.092) on feeding DPKC diets. All the lactation parameters varied with time of collection, and diet × time interactions were noticed for fat, density, protein, 6% FCM yield, and butterfat yield. The feed efficiency tended to increase (P = 0.070) in the buffaloes fed DPKC diets. The profit margins were ₹6.07 and ₹1.63 for the DPKC included diets and feed cost per Kg 6% FCMY, respectively. In  conclusion, the inclusion of DPKC in the diet decreases feed cost without affecting the nutrient intakes, digestibility coefficients, serum biochemical and mineral profile, and lactation parameters.

Effect of microwave/hydrothermal combined ionic liquid pretreatment on straw: Rumen anaerobic fermentation and enzyme hydrolysis

To explore green technology for wheat straw pretreatment, this study combined the microwave or hydrothermal with ionic liquid ([Bmim][OAc]) on wheat straw followed by rumen fermentation. The optimal conditions of microwave assisted ionic liquids pretreatment (M-I) and hydrothermal assisted ionic liquids pretreatment (H-I) treatment were 360 W and 200 °C, and the corresponding lignin removal rates reached 35.3% and 25.4%, respectively. Rumen fermentation showed that the highest volatile fatty acid (VFA) yield was found in M-I group, followed by H-I group at 234 and 180 mg/g, respectively. As for enzymatic hydrolysis, the saccharification rates at 3 days of M-I (360 W) and H-I (200 °C) were determined to be 393 and 320 mg/g. The optimal ionic liquid dosage was determined to be 30% in consideration of cost and VFA conversion rate. M-I pretreatment plus the rumen fermentation enjoyed the benefit of no enzyme addition and high product recovery, which was worth further investigating.

Short-term exposure to the mycotoxins zearalenone or fumonisins affects rumen fermentation and microbiota, and health variables in cattle

Zearalenone (ZEN) and fumonisins (FUM) jeopardize fertility and health in cattle; yet, their toxigenic effects on rumen health and microbiota, both being crucial for animal health, are not clarified. This study determined the effects of a short-term exposure to ZEN or FUM on the rumen ecosystem, and further evaluated acute implications on health parameters. Six cows were fed a basal diet with 40% grain (dry matter basis) and exposed to either 5 mg of ZEN or 20 mg of FUM daily for two consecutive days each, separated by a 7-days washout period. The exposure to ZEN or FUM led to a reduction of Lachnospiraceae and Prevotellaceae in the rumen. Similarly, ZEN lowered the ruminal pH and total short-chain fatty acid concentration, despite increased rumination activity of the cows. Fumonisins increased the number of observed features and significantly impacted β-diversity structure and metagenome predicted function. At the systemic level, FUM exposure suggested an immediate hepatotoxic effect, as evidenced by increased liver enzyme concentrations, which were accompanied by altered heart and respiratory rates. Similarly, ZEN increased the body temperature up to a mild fever. Concluding, short-term exposure to ZEN and FUM can harm the rumen ecosystem and acutely impair systemic health.

Novel insights into heat tolerance using metabolomic and high-throughput sequencing analysis in dairy cows rumen fluid

Heat stress influences rumen fermentative processes with effects on the physiology and production of dairy cows. However, the underlying relationship between rumen microbiota and its associated metabolism with heat tolerance in cows have not been extensively described yet. Therefore, the main objective of this study was to investigate differential heat resistance in Holstein cows using rumen bacterial and metabolome analyses. We performed both principal component analysis and membership function analysis to select seven heat-tolerant (HT) and seven heat-sensitive (HS) cows. Under heat stress conditions, the HT cows had a significantly (P < 0.05) higher propionic acid content than the HS cows; while measures of the respiratory rate, acetic, and butyric acid in the HT cows were significantly (P < 0.05) lower compared with the HS cows. Also, the HT cows showed lower (P < 0.01) rectal temperature and acetic acid to propionic acid ratio than the HS group of cows. Omics sequencing revealed that the relative abundances of Muribaculaceae, Rikenellaceae, Acidaminococcaceae, Christensenellaceae, Rikenellaceae_RC9_gut_group, Succiniclasticum, Ruminococcaceae_NK4A214_group and Christensenellaceae_R-7_group were significantly (P < 0.01) higher in the HT cows; whereas Prevotellaceae, Prevotella_1, Ruminococcaceae_UCG-014, and Shuttleworthia were significantly (P < 0.01) lower in HT cows compared to HS cows. Substances mainly involved in carbohydrate metabolism, including glycerol, mannitol, and maltose, showed significantly higher content in the HT cows (P < 0.05) compared to that in the HS cows. Simultaneously, distinct metabolites were significantly correlated with differential bacteria, suggesting that glycerol, mannitol, and maltose could serve as potential biomarkers for determining heat resistance that require further study. Overall, distinct changes in the rumen microbiota and metabolomics in the HT cows may be associated with a better adaptability to heat stress. These findings suggest their use as diagnostic tools of heat tolerance in dairy cattle breeding schemes.

Association between aflatoxin M1 excretion in milk and indicators of rumen fermentation in bovines

Aflatoxins and its metabolites negatively impact the ruminant health and production. The present cross-sectional study was aimed to determine the effect of aflatoxins on rumen fermentation by deducing the correlation between the aflatoxin M1 (AFM1) excretion in milk and indicators of rumen fermentation in bovines. The indicators of rumen fermentation were taken into account and correlated with AFM1 concentration in milk of 120 bovines (cattle (n = 82) and buffalo (n = 38)). The AFM1 in milk samples (n = 120) was quantified by ELISA kit. The correlation analysis revealed that with increase in excretion of AFM1 in milk, the pH (r = 0.38), methylene blue reduction time (MBRT) (r = 0.43), sedimentation activity time (SAT) (r = 0.31) and ammonia nitrogen content (r = 0.34) of rumen liquor increase, whereas the total volatile fatty acid (TVFA) content (r =  - 0.25), total bacterial count (TBC) (r =  - 0.43) and total protozoal count (TPC) (r =  - 0.14) of rumen liquor decrease. The results of the present study suggest that the presence of aflatoxins in rumen could have negative effect on the process of rumen fermentation. Therefore, the prevention of primary entry point(s) of AFB1 through the feed of bovines is important for the animal health as well as public health.

Alternative pathways for hydrogen sink originated from the ruminal fermentation of carbohydrates: Which microorganisms are involved in lowering methane emission?

Agriculture is responsible for a great share of the anthropogenic sources of greenhouse gases that, by warming the earth, threaten its biodiversity. Among greenhouse gas emissions, enteric CH4 from livestock is an important target to slow down climate changes. The CH4 is originated from rumen fermentation and its concentration is affected by several factors, including genetics and nutrition. Ruminants have an extraordinary symbiosis with microorganisms (bacteria, fungi, and protozoa) that ferment otherwise indigestible carbohydrates, from which they obtain energy to grow and continue actively producing, among other products, volatile fatty acids, CO2 and H2. Detrimental ruminal accumulation of H2 is avoided by methanogenesis carried out by Archaea methanogens. Importantly, methanogenesis is not the only H2 sink pathway. In fact, other bacteria can reduce substrates using metabolic hydrogen formed during carbohydrate fermentation, namely propionate production and reductive acetogenesis, thus lowering the CH4 produced. Although the complexity of rumen poses challenges to mitigate CH4 production, the emergence of sequencing techniques that allow the study of microbial communities, gene expression, and metabolome are largely contributing to unravel pathways and key players in the rumen. Indeed, it is now recognized that in vivo emissions of CH4 are correlated to microbial communities, and particularly with the abundance of methanogens, several bacterial groups, and  their genes. The goal of CH4 mitigation is to work in favor of the natural processes, without compromising rumen function, animal health, and productivity. Notwithstanding, the major challenge continues to be the feasibility and affordability of the proposed solutions.

Mitigation of ruminal methane production with enhancing the fermentation by supplementation of different tropical forage legumes

The aim of this research was to evaluate the influence of forage species adapted to the tropical region of Ecuador on gas production, enteric methane, digestion, and ruminal fermentation. The tree forage evaluated were C. arborea, E. fusca, B. forficata, E. poeppigiana, C. argentea, G. sepium, C. tora, and F. macrophylla. Ruminal fluid of four adult sheep fistulated with permanent cannulas in the rumen was used in the in vitro gas production technique. The in vitro gas production parameters were lower (P < 0.05) in the C. arborea (A = 41.68 mL gas/g DM, c = 0.044%/h and Lag = 1.654 h) and the average gas production rate for B. forficata was 1.017 mL/h (P < 0.05). C. arborea presented higher (P = 0.0001) effective degradation and real DM digestibility (40.461 g/kg and 82.51 mg/g, respectively). With respect to VFA, the highest (P < 0.05) proportion of acetic, propionic, and butyric was observed in C. arborea, G. sepium, and E. poeppigiana (72.52, 23.09, and 7.44 mol/100 mol, respectively) and the lowest (P = 0.0001) ratio: acetic/propionic was observed in G. sepium (2.92 mol/100 mol). The content of NH₃-N (mg/L) showed no difference. The lowest (P = 0.0001) methane production was observed in C. arborea (1.23 mL CH₄/g DM). The use of forage species of tropical climate rich in secondary metabolites in ruminant diets has the capacity to reduce the gas production and enteric methane; however, this is at the expense of the reduction of the fermentation of organic matter in the rumen.