Biomass Yield, Proximate Composition, In Vitro Gas Production and Nutritional Values of Sprouted Barely Grains on Rice, Wheat and Bean Straws

This overview highlights the potential of using agricultural byproducts as a feed source for ruminants, emphasizing that large quantities of agricultural by-products are produced annually, but are not fully utilized as animal feed, leading to waste and pollution [1]. In Egypt, the area cultivated with rice is about 1.62 million feddan, producing about 4.86 million tons of rice straw, wheat is about 3.17 million feddan, producing about 6.34 million tons of wheat straw and faba beans is about 111.53 thousand feddan, producing about 167.30 thousand tons of bean straw [2]. Rice straw is of poor nutritive value for ruminants related to its low protein content, high fiber content and low palatability. Few attempts were tried to improve nutritive value of rice straw [3]. Sprouting barely increased the Crude Protein (CP) content while decreasing Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Acid Detergent Lignin (ADL) in rice straw [4]. Sprouting activities in the seeds have many changes as in seed protein converted to essential amino acids, carbohydrates are converted to sugars and fats are converted to essential fatty acids. These activities increase because of increasing enzymes levels [5]. Sprouting is a simple, well-known technique that is used to germinate seeds of various forage crop species such as oats, barley, corn and wheat to produce valuable green fodder [6]. The sprouting process is characterized by its high yield, sustainable production throughout the year, efficient water use [7] and short growth time compared to field-grown forage production [8].

Moreover, sprouting uses 99% less land than that required for conventional production methods [4], so it is valuable for countries that have little available land for cultivation or unsuitable land. Furthermore, the seed enzymes are activated by sprouting, as they change the starch, protein and lipids within the grain to sugars, amino acids, and essential fatty acids, respectively, which are simpler forms for consumption [7]. This explains why sprouts are much easier for animals to digest than dry seeds or other conventional fodder [7]. One of the main disadvantages of sprouting is the decrease in dry matter and the increase in moisture content compared to those produced by traditional methods [9,10], which may negatively affect the consumption responses of animals [11]. In this respect, Akbag et al. [12] suggested that adding hay to sprouts would decrease the moisture content and increase the dry matter content. Sprouting is an Innovative method for production green fodder throughout the year to provide consistent high amount of food 100% organic and the systems of environment friendly technologies as well as reduce the cost of feeding ruminants [13].

Sprouted barley grain refers to barley that has been germinated by soaking in water and allowed to sprout in a controlled environment, often using hydroponics. This process enhances the nutritional value of the grain, particularly increasing enzyme content and making it easier to digest. Sprouted barley is a valuable feed ingredient for various livestock, including poultry, rabbits, and ruminants [14]. Cereal and legume straws differ significantly in their chemical composition, particularly in protein and fiber content. Legume straws generally have higher protein content and lower fiber content compared to cereal straws [15]. The study aimed to determine the biomass production, chemical composition, nutritional values and gas production parameters in the laboratory of barley grains germinated on rice, wheat and bean straws.

Production of sprouted barley

Using a hydroponic watering system with straws for the process of barely germination, during one period of 12 days was done to get shoot sprouts with 15-20cm of length. The hydroponic system was kept at control room temperature maintained at 21-22 ºC and 75% of the relative humidity. A growing plan was conducted using a steel hydroponic stand, size 2.10×0.50×1.9m equipped containing 6 shelves (30cm apart shelves) with capacity of 42 polyethylene trays sized 60×30x3cm (0.18m2) each. Barley grains were washed and soaked in tap water overnight (about 12 hours) before sowing and stored in a dark area to allow for initial germination. With a seed rate of 2.78kg/m2 for barley grains, the seeding rates were around 500 grams of barley grains per tray [16]. Sprouted barley was produced according to the described method using about 10cm thick layer of chopped straws [17]. Sprouted Barley grain (SB) was produced using agricultural by-products such as Rice Straw (RS), Wheat Straw (WS) and bean (faba bean) straw (BS) as bedding media for growing Barley Grain (BG). Barley grain was washed and soaked in tap water overnight (about 12 hours) before sowing and stored in a dark area to allow for initial germination. The irrigation of different shelves was designed depending on fog system. The irrigation with 0.5% urea solution was delivered via 4 fog sprayers (32L/hour) for each shelf. The fog system was automated by using a digital timer (2 minutes/hour/24 hours) to control water pumping (water pump 0.5 horse powers) from the water tank. Sprouted barley treatments were Sprouted Barley on Rice Straw (SBRS), Sprouted Barley on Wheat Straw (SBWS) and Sprouted Barley on Bean Straw (SBBS).

Proximate analysis

The fresh crops were weighed and the samples were taken and dried in the air oven at 60 °C until complete drying to estimate the dry matter content and dry crop yield. Representative samples were ground and chemically analyzed to determine the various components according to AOAC [17]. Fiber fractions (NDF, ADF and ADL) were determined according to the methods of Van Soest [18].
Cellulose=ADF-ADL
Hemicellulose=NDF-ADF

Nutritional values

Total Digestible Nutrient (TDN) was computed according to AAFCO [19]:
TDN %=40.2625+0.1969*CP+0.4228*NFE+1.1903*EE- 0.1379*CF
Digestible Crude Protein (DCP) was calculated according to Villamide and Fraga [20]:
DCP %=0.876*CP-3.467
Where: CP=Crude Protein; CF=Crude Fiber; EE=Ether Extract; NFE=Nitrogen-Free Extract.
Gross Energy (GE) and Digestible Energy (DE) were calculated according to MAFF [21]:
GE (Mcal/kg DM) = (0.226*CP+0.177*CF+0.407*EE+0.192*NFE) /4.184
DE=(GE*(87.9-(.88*CF)))/100

In vitro gas production

process outlined by Menke and Steingass [22] was followed for the in-vitro gas production evaluation. Briefly, 100mg of the air-dry feed ingredients were precisely weighed into a 50ml glass syringe that was calibrated and had plungers in vitro gas production, the buffer solution was employed [23]. The buffer comprised 2.8g of NaCl, 0.1g of CaCl₂, 0.1 MgSO 4.7 H₂O, 2.0g of KH₂PO₄, and 6.0g of Na₂HPO₄ that were dissolved in 1L of distilled water. Next, after adjusting the pH to 6.8, CO₂ flushed for 15 minutes. Three rumencannulated lambs fed ad libitum with a mixture of commercial concentrate and rice straw were used to collect the rumen contents (50 percent liquid and 50 percent solid) according to Bueno et al. [24]. Before the animals were fed in the morning, the contents of their rumen were gathered. Both liquids and solids samples were brought to the lab in anaerobic conditions after being placed in insulated flasks preheated to 39 °C. Squeezed through four cheesecloth layers, the rumen contents were maintained in a water bath with CO₂ saturation at 39 °C until inoculation. In a water bath held at 39 °C with CO₂ saturation, the buffer and inoculant (2:1v/v) were combined [25-27]. After pipetting 15ml of buffered rumen fluid containing the feed samples into each syringe, the syringes are dropped right into the water bath, which is set at 39 °C. For every experiment, three runs were carried out. Each run consisted of two syringes filled with buffered rumen fluid, which were then incubated and used as the blank. The syringes are gently shaken every two hours, and the incubation is stopped when the 96-hour gas volume is recorded. The gas generation was measured after incubation for 3, 6, 9, 12, 24, 48, 72 and 96 hours in accordance with the procedure described by Theodorou et al. [28] linear regression analyses were determined for headspace gas pressure versus gas volume. To ascertain the methane (CH₄) concentration, 10μl of the headspace gas was extracted from the bottles at various incubation durations (3, 6, 9, 12, 24, 48,72 and 96 hours) and injected straightinto a GC, following the procedure outlined by Pellikaan et al. [29]. The reported gas and methane readings are expressed per 200mg of DM, and the total gas values are adjusted for the blank incubation. Ørskov and McDonald [30] defined fermentation kinetics as follows:
Y=a+b*(1-e-ct)

Where: a is the gas production from the immediately soluble fraction; b is the gas production from the insoluble fraction; c is the gas production rate constant for fraction b. Y is the gas production (ml/g OM) at time (t).

Gas Produced after 3 hours (GP3) of incubation was employed as a new method to measure Gas Production Induced by Fermentation of the Soluble Fraction (GPSF) to evaluate feeds from those parameters. According to van Gelder et al. [31], the gas produced between the hours of GP3 and GP24 of incubation might be utilized to estimate the Gas Production due to Fermentation of the Insoluble Fraction (GPNSF) as follows:
GPSF=(GP3hr*0.99)-3
GPNSF=1.02*(GP 24hr-GP3hr)+2

Where: GPSF is the gas production from a soluble fraction (ml/g DM); GPNSF is the gas production from a non-soluble fraction (ml/200 mg DM); and GP 3hr is the net gas production (ml/200 mg DM) during the three hours.

The energy values were calculated from the amount of gas produced at 24hr of incubation with supplementary analyses of crude protein, ash and crude fat. This approach was developed by the research group in Hohenheim (Germany) and is based upon extensive in vitro incubation of feedstuffs [32,33].
ME (Mcal/kg DM)=(2.2+0.136*GP+0.057*CP)/4.184 NE (Mcal/kg
DM)=(2.2+0.136*GP+0.057*CP+0.149*EE)*2.2/14.64

Where: ME is the metabolizable energy (Mcal/kg DM), GP is 24hr net gas production (ml/200mg DM), CP is crude protein (% of DM) and EE is either extract (% of DM).

Organic Matter Digestibility (OMD) was calculated as established by Getachew et al. [34]:
OMD (%)=14.88+0.889*GP+0.45*CP+0.0651*A

Where: OMD is organic matter digestibility (%), GP is 24hr net gas production (ml/200mg DM), CP is crude protein (% of DM), A is ash (% of DM).

Effective Dry Matter Degradability (EDMD) from in vitro gas production data can be calculated using the equation developed by Ørskov and McDonald [30]:
EDMD=(a+b)+((a*b)*c)/(c+k)

Where, ‘a’ is the gas production from the soluble fraction, ‘b’ is the potential gas production from the insoluble fraction, ‘c’ is the gas production rate constant and ‘k’ is the rumen outflow rate, which is at the maintenance level and is equal to 2% per hour.

The following formula was used to determine Short Chain Fatty Acids (SCFA) in accordance with Getachew et al. [33]:
SCFA(Mm)=(-0.00425+0.0222*GP24hr)*100

Where: GP is the soluble fraction’s net gas production over 24 hours (ml).

The expected Dry Matter Intake (DMI) of silage was computed using the formula below, in accordance with Blümmel and Ørskove [35]:
DMI=1.66+0.49*a+0.0297*b-4*c

Where: c is the gas production rate (ml/hr), a is the gas production from the soluble fraction (ml) and b is the gas production from the insoluble fraction (ml).

Czerkawski [36] calculated the generation of microbial protein (MP) as 19.3g microbial nitrogen per kilogram OMD.
MCP(g/kg DM)=OMD*19.3*6.25/100

Statistical analysis

Data was analyzed using general linear model’s procedure adapted by IBM SPSS Statistics [37] for user’s guide with one-way ANOVA. Significant differences in the mean values among dietary treatments were analyzed by Duncan’s tests within SPSS program set at the level of significance P<0.05 [38].

Proximate composition of ingredients

Proximate composition of barley grain and different straws in Table 1 showed that DM content was nearly similar for different ingredients. The proximate composition also revealed that Barley Grains (BG) recorded the highest contents of OM, CP, EE and NFE and lower contents of CF, ash, NDF, ADF, ADL, cellulose and hemicellulose compared to different types of straws (RS, WS and BS). Comparison of the proximate composition of RS, WS and BS revealed higher OM and NFE contents in WS than those in RS and BS, while higher ash content was done in RS than those in WS and BS. Whereas, higher CP content and lower EE content were observed in BS than those in RS and WS. Furthermore, higher contents of CF, NDF, ADF, cellulose and hemicellulose were detected in WS compared with RS and BS, while higher ADL content was observed in BS than those in RS and BS. Barley grains have a high starch content, about 60% (55-63% of DM), protein content (about 11-12% with values ranging from 9.5 to 13% of DM) and fiber content (4-6% CF, 5-7% ADF, 18-24%) [39] and is an important feed ingredient for major livestock species [40].

Table 1:Proximate composition and fiber fractions of barley grain, rice, wheat and bean straws.

Straw is high in fiber and low in other nutrients, including protein, sugars, minerals and vitamins. Generally, straw from cereals and grasses are lower in nutritional value than straw from legumes. The leaf-to-stem ratio, which is influenced by harvesting conditions, can largely determine the nutritional value of straw, especially for legume species and should be avoided leaf shedding if the straw is used as animal feed [41]. Cereal and legume straws differ significantly in their chemical composition, particularly in protein and fiber content. Generally, legume straws have a higher protein content and lower fiber content compared to cereal straws [42]. Rice straw is a good source of energy but is low in protein (2-5%) and its high silica content results in low digestibility and it is considered as a low-quality roughage [43]. The composition of bean straw depends on the proportions of stems and leaves: Stems have a low protein content (8% and 4% DM, respectively) while the leaves are much richer in protein (20% of DM) [44]. Bean straw contains about 5-11% protein of DM and is rich in fiber (crude fiber 38-45% DM). However, it has better nutritive value than cereal straws due to a higher protein and a lower fiber content, though the composition is variable: for instance, the DM of stem-rich bean straw was reported to contain 61% NDF vs. 51% for leaf-rich straw [40].

Biomass yield of sprouted barley grains on straws

The yield of sprouted barley grain in Table 2 revealed that fresh and dry crop yield were higher significantly (P<0.05) for SBBS compared with SBWS with insignificant differences with SBRS. Fresh yield ranged from 7.45 to 7.80kg and dry yield ranged from 1.76 to 1.93kg per one kg barley grains. Similar results showed that the concept of putting one kilogram of grain into a hydroponic system and producing 6 to 10 kilograms of fresh green sprouts, independent of weather and at any time of year, is of interest by Kruglyakov [44]. Commercial sprouts growers have reported that 1kg of seed yielding about 6-10kg of fresh sprouts, while trial yields from experiments found that 1kg of seed yielding about 5-8kg of fresh sprouts, indicating an increase in fresh weight with sprouting of grain [45]. Saidi and Abo Omar [11] showed that the green fodder yield in the 8 days germination cycle was 7.5kg per 1kg barley grains of green fodder. The fresh and dry yield of sprouted barley in our study tended to increase than those obtained by Mohsen et al. [46] who found that fresh yield of sprouted barley on rice, wheat and bean straws ranged from 6.50 to 6.89kg and dry yield from 1.52 to 1.72kg per one kg grains. Also, Emam [47] reported that fresh yield of sprouted barley grains varied from 6.2 to 6.5kg per one kg grain. The amount of green fodder yield ranged from 1.95 to 2.30kg per 100g of barley grain plus 500g of media (rice straw, Acacia saligna and 50% rice straw + 50% Acacia saligna) at 15 days [48].

Table 2:Biomass yield, proximate composition and fiber fractions of sprouted barely grains on rice, wheat and bean straws.

a, b, c: Means in the same row with different superscripts differ significantly at P<0.05.

Proximate composition of sprouted barley grains on straws

Results of proximate composition of sprouted barley grains on rice, wheat and bean straws were shown in Table 2. The DM content was significantly (P<0.05) in SBBS than that of SBWS with insignificant differences with SBRS. Whereas OM and CF contents were significantly (P<0.05) higher in SBWS and SBBS compared to SBRS. While CP and EE content was nearly similar for sprouted barley grain on different straws. Whereas NFE content of SBWS was significantly higher than those of SBRS with insignificant differences with SBBS. Meantime, ash content was significantly (P<0.05) high in SBRS followed by SBBS, but SBRS had the lowest content. The variations in the chemical composition of the different sprouted barley grains might be attributed to the differences in the composition of different straws as shown in Table 1. The similar CP content of different sprouted barley grains might be due to using urea water solution in irrigation. This finding may be attributed to an increase of the activity of sprouted barley hydrolytic enzymes and lead to improvements in chemical composition of straws. Sprouting barley can significantly increase CP content of straws [49]. The chemical composition of sprouted barley differs from the original grains, which the contents of CP, CF, Ash, EE were increased whereas OM and NFE decreased (P<0.05) in the hydroponic barley when compared with the original grain [7]. Sprouted barley on straws, as a feed, exhibits a higher content of crude protein, acid detergent fiber, lignin and ash compared to traditional diets [14]. Sprouted barely increased CP and NFE contents and decreased CF contents in treated rice and acacia straws [48]. The values of chemical composition obtained in the current study were nearly like those presented by Mohsen et al. [46].

Fiber fractions of sprouted barley grains on straws

Results of fiber fractions in Table 2 illustrated that the contents of NDF and cellulose were higher significantly (P<0.05) in SBWS than those in SBRS and SBBS. While ADF content was higher significantly (P<0.05) in SBWS and SBBS compared to SBRS. Whereas ADL content was higher significantly (P<0.05) in SBBS than that in SBRS and SBWS. However, hemicellulose content was higher significantly (P<0.05) in SBRS and SBWS than that in SBBS. The changes in the fiber fractions of different types of sprouted barley grain are due to differences in fiber fractions between different varieties of straws as shown in Table 1. The chemical composition of sprouted barley differs than the original grains, which the contents of NDF, ADF and ADL were increased (P<0.05) in the hydroponic barley when compared with the original grain [7]. Sprouted barely decreased NDF, ADF and ADL contents in treated rice and acacia straws [48]. Sprouting barley can significantly alter the fiber fractions of straws, primarily reducing the content of Neutral, making them easier for animals to utilize [49].

Accumulative gas production of sprouted barley grains on straws

Accumulative Gas production of sprouted barley grain on different straws during the 96 hours incubation period are presented in Table 3. The values of accumulative gas production during the different incubation times were higher significantly (P<0.05) in SBRS followed with SBWS, but SBBS had the lower values. These results confirm the increase in gas production values with increasing NFE content and decreasing CF and fiber fractions content as shown in Table 2. Gas production increased sharply during the first 12 hours of incubation then steadily increased during the period from 12 to 24 hours and slightly increased as the incubation period extended to 96 hours (Figure 1). In vitro gas production from sprouted barley grain, compared to unsprouted barley, often exhibits increased levels, particularly of CO2. This is due to the breakdown of complex carbohydrates during sprouting, making them more readily available for fermentation in the in vitro system. Studies have shown that sprouted barley can lead to higher digestibility and improved nutrient absorption compared to unsprouted barley [50]. In vitro gas production experiments on sprouted barley grains, whether grown on straws or not, demonstrate that sprouting increases the digestibility of nutrients and reduces the production of methane. Sprouting enhances fermentation rates, particularly for carbohydrates and protein. Additionally, sprouted barley can be grown on various straws, including rice straw, wheat straw, and bean straw [14].

Table 3:Accumulative gas production (ml/200mg DM) of sprouted grains on rice, wheat and bean straws.

a, b, c: Means in the same row with different superscripts differ significantly at P<0.05.

Fgure 1:Accumulative gas production of sprouted barely grains on rice, wheat and bean straws.

By incubating substrate in buffered rumen fluid, in vitro Gas Production (GP) assessment is primarily used to assess the nutritional value of bovine feeds [51-53]. When feedstock is incubated in vitro with buffered rumen fluid, the carbohydrates are fermented to produce Short-Chain Fatty Acids (SCFA), microbial cells and mainly CO and CH gases. The fermentation of carbohydrates to acetate, propionate, and butyrate produces gas. Compared to the fermentation of carbohydrates, the creation of gas from protein fermentation is comparatively minor, and the contribution of fat to gas production is insignificant [54,55]. According to Haddi et al. [55], the rate and degree of GP were significantly correlated negatively with both ADF and NDF. Carbohydrates significantly impact the amount of gas generated during fermentation. Diets rich in soluble carbohydrates tend to produce less gas, while those with higher Water-Soluble Carbohydrate (WSC) content, such as high- WSC cultivars, can lead to greater gas production [56].

Kinetic parameters of sprouted barley grains on straws

Kinetics parameters of gas production of sprouted grains on different straws are shown in Table 4. Kinetics parameters as gas production from the rapidly degradable fraction (a) the potentially degradable fraction (b) and the rate of gas production (c) were significantly (P<0.05) higher in SBRS followed by SBWS, but SBBS had the lower values. The kinetics parameters (a, b, and c) for gas production in sprouted barley grain, as estimated in studies, generally show an increase in the rapid degradable fraction (a), the potentially degradable fraction (b), and the rate of gas production (c) as the sprouting process progresses. Specific values vary depending on the study and the stage of sprouting, but a general trend is an increase in the degradability of the grain’s components [57]. The kinetic and nutritional parameters of gas production from sprouted barley grains when used with rice, wheat and bean straws are influenced by the straw type and the sprouting process itself [58].

Table 4:Kinetics parameters and fractions of gas production of sprouted barely grains on rice, wheat and bean straws.

a, b, c: Means in the same row with different superscripts differ significantly at P<0.05.

The kinetic parameters (a, b, and c) of gas production from sprouted barley grain and straw refer to the rate and extent of gas production during fermentation. ‘a’ represents the immediately degradable fraction, ‘b’ the potentially degradable fraction, and ‘c’ the degradation rate. These parameters, when combined, help understand how quickly and to what extent a substrate can be broken down by microbes during digestion, such as in the rumen of ruminants [57]. Sprouted barley, due to the enzymatic breakdown of its cell walls during sprouting, has a higher ‘a’ fraction (immediately degradable) compared to unsprouted barley or straw. This leads to faster and more extensive gas production. Straw, with its higher fiber content, has a lower ‘a’ fraction but a potentially higher ‘b’ fraction that is broken more slowly [14]. The parameters (a, b, and c) provide valuable insights into the fermentation characteristics of sprouted barley and straw, helping to understand their nutritional value and digestibility in animal feeds, particularly in ruminant diets [50]. The kinetics of gas production from sprouted barley grains on straw involve a few key parameters: gas production rate (c), total gas production (A), and time to produce a certain percentage of total gas production. Barley grain typically shows a higher gas production rate and total gas production compared to straw, with a shorter time to produce a given percentage of total gas [58]. The soluble fraction, insoluble fraction, and degradation rate are the three characteristics that now characterize ruminant forages [59].

Gas fractions of sprouted barley grains on straws

Gas Production from Fermentation of the Soluble Fraction (GPSF) and Insoluble Fraction (GPNSF) were higher significantly (P<0.05) in SBRS followed by SBWS, the lower values were in SBBS (Table 4). In the context of animal feed, sprouted barley grain and straw are often evaluated using gas production techniques to assess their digestibility and nutritional value. Gas Production Fractions (GPSF) and Potential Gas Production (GPNSF) are key metrics in these assessments. Sprouting barley increases the amount of fiber, which may lead to a higher potential for gas production than unsprouted barley [60]. Gas Production Fractions (GPSF and GPNSF) refer to the amount of gas produced by rumen microorganisms during the fermentation of feedstuffs. Sprouted barley grain on straw, when fed to ruminants, influences these fractions. The sprouted barley grain itself contributes to the overall gas production, while the straw can also be a source of gas production depending on its digestibility and the presence of microorganisms [61]. In essence, sprouted barley grain is likely to contribute more to gas production than straw due to its higher digestibility and starch content. However, the specific amount of gas produced from both feedstuffs will depend on a variety of factors, including the type of straw, its digestibility and the overall diet composition [62]. Gas production from soluble and insoluble substances differs significantly due to their different interactions with solvents and digestion processes.

Soluble substances, like some sugars and gases, are readily dissolved and can be more easily broken down, potentially leading to more rapid gas production. Insoluble substances, such as certain fibers, require bacterial fermentation in the large intestine, which can also produce gas, but often at a slower rate [63]. The type of substance (soluble or insoluble) and its digestibility, along with the activity of gut bacteria, are key factors influencing the rate and extent of gas production [64].

Methane production (CH₄)

Methane production of sprouted barley grain on different straws during the 96 hours incubation period are presented in Table 5. Values of methane production during the different incubation times were lower significantly (P<0.05) in SBRS followed with SBWS, but SBBS had the higher values. These results confirm the increase of methane production values with increasing CF and fiber fractions contents as shown in Table 2. Methane production increased sharply during the first 12 hours of incubation then steadily increased during the period from 12 to 24 hours and slightly increased as the incubation period extended to 96 hours (Figure 2). In vitro methane production from sprouted barley grain on straw is influenced by several factors, including the specific conditions of the in vitro incubation, the composition of the substrate (sprouted barley and straw) and the microbial community present. Studies have shown that sprouted barley can alter methane production compared to using barley grain alone and the type of straw used (e.g., rice straw) can also play a role [65]. The type of straw used as a substrate can impact methane production. For example, rice straw has been used in studies involving sprouted barley and its properties (e.g., particle size, amount relative to grain) can influence fermentation and methane release [66]. In vitro methane production from sprouted barley on straw is a complex process influenced by various factors. Understanding these factors is crucial for optimizing the use of sprouted barley and straw as feed while minimizing methane emissions [67].

Table 5:Methane production (ml/200mgDM) of sprouted grains on rice, wheat and bean straws.

a, b, c: Means in the same row with different superscripts differ significantly at P<0.05.

Fgure 2:In vitro methane production of grains sprouted on rice, wheat and bean straws.

Fermentation Products of sprouted barley grains on straws

Short Chin Fatty Acids (SCFA): Fermentation product in Figure 3, revealed that the concentration of Short Chin Fatty Acids (SCFA) was higher significantly (P<0.05) in SBRS followed by SBWS, whereas it was lower in SBBS. Short Chin Fatty Acids (SCFA) are the main products of fermentation, including acetate, propionate and butyrate, which are important energy sources for ruminants. Gas production is associated with volatile fatty acid production following fermentation of substrate [68]. In vitro Short-Chain Fatty Acid (SCFA) production involves simulating the fermentation process of gut microbiota in a lab setting to study SCFA production and its impact on health. This method allows researchers to explore how different substrates, like dietary fiber, influence SCFA production [69]. The production of SCFA, which was predicated on the fermentation of carbohydrates, was closely correlated with the gas production of various feed classes cultured in vitro in buffered rumen fluid [70,71]. In vitro Short-Chain Fatty Acid (SCFA) concentrations vary depending on the specific SCFA, the location within the gut and the experimental conditions. Typical concentrations of SCFA, with acetate being the most abundant, followed by propionate and butyrate. In Vitro, studies often investigate SCFA production from different substrates and their effects on various biological processes [72]. McDonald et al. [71] have revealed that the concentration of SCFA measured in this investigation falls within the usual range of 70 to 150mM.

Fgure 3:Short Chin Fatty Acids (SCFA) and Microbial Protein Production (MCP) of sprouted barely grains on rice, wheat and bean straws.

Microbial Protein production: Gas production can indicate the extent of Microbial Protein Production in the rumen (MCP) of sprouted barley grain on different straws is shown in Figure 3. The SBRS revealed significantly (P<0.05) higher MCP followed by SBWS, but the lower value detected in SBBS. These results might be due to more utilization of rice straw by rumen microbial. According to Lu et al. [72], rumen MCP output increases significantly when fed an energy-rich diet while remaining unaffected by a protein-rich diet. The main variables influencing the energy available for rumen microbial development (namely, MCP synthesis) are the sources and amounts of fed carbohydrates, while provided protein has an impact on the amount of microbial Dry Matter (DM) produced per unit of fermented carbohydrates [73]. Only when more Non-Fiber Carbohydrates (NFC), known as the primary energy source for ruminal microbes, are supplied to the animals will more protein N be absorbed into the rumen MCP [74]. Gas production in the rumen can be used as an indicator of Microbial Protein (MCP) production when feeding sprouted barley grain on different straws. The amount and rate of gas production are related to the extent of microbial fermentation and protein synthesis within the rumen [75]. Rumen microbes utilize feedstuffs to produce microbial protein, which is a crucial source of amino acids for the ruminant animal. Also, gas production is a useful indicator of rumen MCP synthesis [76].

Predicting DMI: The prediction of Dry Matter Intake (DMI) of sprouted barley grain on different straws is shown in Table 6. The predicted DMI expressed as kg per day or kg per kg metabolic Live Body Weight (LBW0.75) were higher significantly (P<0.05) in SBRS followed by SBWS, but SBBS recorded the lower values. In vitro gas production techniques can be used to predict Dry Matter Intake (DMI) of sprouted barley grain and straw-based diets. The rate and extent of gas production, along with parameters like potential cumulative gas production (B), rate of gas production (c), and the initial lag time (lag), can be used to predict the DMI of different feeds [77]. The rate and extent of gas production (measured at various time points during incubation) can be used to predict how much of the feed an animal will consume (DMI) [78]. In vitro techniques can be used to assess how sprouted barley affects the digestibility and gas production of straw-based diets, allowing researchers to predict how these changes will influence DMI [79]. The concentration of cell wall components limits the amount of forage consumed [80,81]. High correlations between DMI of forages and in vitro GP investigations have been reported by several authors [82].

Digestibility: As shown in Table 6, Effective Dry Matter Degradability (EDMD) and Organic Matter Digestibility (OMD) were significantly (P<0.05) higher in SBRS followed by SBWS, whereas SBBS recorded the lower values. In vitro gas production can estimate the digestibility of Organic Matter (OMD) and Dry Matter (IVDMD). In vitro techniques can be used to assess how sprouted barley affects the digestibility of straw-based diets [83]. The effective degradability of Dry Matter (DM) of sprouted barley on straws is influenced by several factors, including the sprouting process itself and the potential for interactions with the straw in a mixed diet. While sprouting can improve the digestibility of barley grain, the overall effect on DM degradability when fed with straw depends on the specific conditions and proportions of the feed [84]. It is commonly recognized that the most suitable and widely used laboratory methodology for estimating the digestibility of feedstuffs for ruminants is the in vitro technique. According to Taghizadeh et al. [85], there was a significant positive link between gas production and in vitro dry matter disappearances. The sprouting process increases the digestibility of nutrients, making them more readily available for animals. Sprouted barley also shows higher levels of digestible nutrients compared to traditional diets [14].

Nutritional values: Nutritional values illustrated in Table 6 indicated that Total Digestible Nutrient (TDN), Digestible Crude Protein (DCP), Gross Energy (GE) and Digestible Energy (DE) contents tended to increase in SBWS with insignificant (P>0.05) with both SBRS and SBBS. These results revealed that sprouting process improved the feeding values of sprouted barley grains as calculated from chemical composition. Sprouting barley grains on different straws increased its contents of TDN by from 40-45% to 62-63%, DCP from 1.5-2.0% to 11.50 to 11.75% and seems a good quality forage for ruminants. The improvement of nutrient quality of sprouted barley due to the ability of sprouted germinated plants to transport nutrients to the roots to meet the requirement for strong healthy vegetative growth, besides increasing protein, vitamins and minerals content during process [86,87]. Sprouting barely can increase the TDN content of straw-based diets for ruminants. This happens because sprouting breaks down structural and complex carbohydrates into simpler sugars, making them easier to digest. Sprouting barely significantly alters its nutritional profile, especially when combined with rice, wheat and bean straws [88].

Table 6:Fermentation product and nutritional parameters of sprouted barely grains on rice, wheat and bean straws.

a, b, c: Means in the same row with different superscripts differ significantly at P<0.05.

Fgure 4:Energy contents of sprouted barely grains on rice, wheat and bean straws.

Energy values: The effect of different straws on energy contents of sprouted barley grain are presented in Figure 4. Gross Energy (GE) was significantly (P<0.05) higher in SBWS and SBBS than that of SBRS. Whereas Digestible Energy (DE) contents tended to increase in SBWS with insignificant (P>0.05) with both SBRS and SBBS. The contents of Metabolizable (ME) and Net Energy (NE) were significantly (P<0.05) higher in SBRS followed by SBWS, but SBBS had the lower values. The ME and NE of sprouted barley grain on straw can be estimated using the in vitro gas production technique. This method involves measuring gas production from the feed sample during incubation, which is then used in equations to calculate ME and NEL values [87]. The metabolizable energy value of traditional feeds assessed a positive association with the protein and carbohydrates and a negative association with fiber contents and the metabolizable energy computed from a 24-hour in vitro gas generation [28]. The energy value of various feed classes, especially straws, has also been extensively assessed using the in vitro gas production method [89]. Sprouting barley grains on different straws increased GE from 3.4-3.8Mcal/kg to 4.26-4.51Mcal/kg and seems a good quality forage for ruminants [86].

From these results it could be concluded that sprouting barley grain on rice, wheat and bean straws are a good source of green fodder and utilization of poor-quality agriculture by-products in ruminant feeding. Sprouting barley grain on straws increased biomass yield and improved chemical composition and nutritional values and energy contents, feed intake, rumen fermentation and microbial protein production as well as reduced methane emission with best results with rice straw.

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