Semisolid fermentation of ryegrass straw

Candida utilis, Aureobasidium pullulans, and Trichoderma viride were grown on pretreated ryegrass straw. The pretreatment consisted of hydrolysis of straw with 0.5 N H₂SO₄ (water-substrate, 3:1) at 121 C, 100 C, and room temperature and adjustment of the hydrolysate to pH 4.5 to 5.0 with 5 N NH₄OH. The 121 C pretreatment yielded a material containing 30% sugar and 2.3% N. The fermentation was carried on semisolid substrate (moisture level, 75%) in rotating jars for 2 to 3 days at room temperature. The organisms grew rapidly during the period from 18 to 42 h of incubation. During this period the number of microbial cells increased by 20- to 200-fold, and the level of NH₃-N decreased from 1.3 to 0.9%. The fermentation resulted in a fourfold increase in protein, fivefold increase in crude fat, and 40% increase in the digestibility of straw. The best result in terms of increasing protein and digestibility of straw was obtained when C. utilis was grown on straw preheated at 121 C.     

Bioconversion of wheat straw to ethanol: Chemical modification,enzymatic hydrolysis,and fermentation

Native wheat straw (WS) was pretreated with various concentrations of H₂SO₄ and NaOH followed by secondary treatments with ethylene diamine (EDA) and NH₄OH prior to enzymatic saccharification. Conversion of the cellulosic component to sugar varied with the chemical modification steps. Treatment solely with alkali yield 51–75% conversion, depending on temperature. Acid treatment at elevated tempeatures showed a substantial decrease in the hemicellulose component, whereas EDA-treated WS (acid pretreated) showed a 69–75% decrease in the lignin component. Acid-pretreated EDA-treated straw yielded a 98% conversion rate, followed by 83% for alkali–NH₄OH treated straws. In other experiments, WS was pretreated with varying concentration of H₂SO₄ or NaOh followed by NH₄OH treatment prior to enzymatic hydrolysis. Pretreatment of straw with 2% NaOH for 4 h coupled to enzymatic hydrolysis yield a 76% conversion of the cellulosic component. Acid–base combination pretreatment yielded only 43% conversions. A reactor column was subsequently used to measure modification–saccharification–fermentation for wheat straw conversion on a larger scale. Thirty percent conversions of wheat straw cellulosics to sugar were observed with subsequent fermentation to alcohol. The crude cellulase preparation yielded considerable quantities of xylose in addition to the glucose. Saccharified materials were fermented directly with actively proliferating proliferating yeast cells without concentration of the sugars.     

Anaerobic detoxification fermentation by Rhodospirillum rubrum for rice straw as feed with moderate pretreatment

A novel and effective process was put forward for converting rice straw into feed by combining diluted acid hydrolysis and ammonization with Rhodospirillum rubrum fermentation. After pretreatment with dilute sulfuric or phosphoric acid (1%, w/w) at 100°C, materials were subjected to fermentation under several gases (N₂, CO₂, and air) and different light intensities in a 2-L fermentor. The key indexes of feed for fermented materials were estimated and several toxic substances were investigated during the fermentation. Following sulfuric acid treatment, the true protein of rice straw increased from 29 to 143?g?kg^?1 and the crude fiber decreased from 359 to 136?g?kg^?1 after fermentation at 0.3?L?min^?1?L^?1 of N₂ flow and a light intensity of 3400 lux; and following phosphoric acid treatment, the true protein increased by 286% and the crude fiber decreased by 52% after fermentation at 0.4?L?min^?1?L^?1 of N₂ flow and a light intensity of 3000 lux. Other key contents were also improved for use as feed, and some toxic substances (i.e., furfural, hydroxymethylfurfural, acetic acid, phenol, cresol) produced by the pretreatments could be removed at low levels during the fermentations.     

Different sources of ammonia for improving the nutritive value of low quality roughages

The study was undertaken to investigate the effectiveness of anhydrous NH₃, aqueous NH₄OH and urea + urease as sources of ammonia for treating maize stover, rice and wheat straws at graded treatment rates of 0, 25 and 50 g NH₃/kg DM of roughage and at two moisture levels of 20 and 40% in all combinations in improving dry matter digestibility in vitro (IVDMD), organic matter digestibility in vitro (IVOMD) and crude protein (CP) contents when allowed to react for 15 or 30 days.Rate of ammonia was the most important factor in enhancing IVDMD, IVOMD and CP. Moisture level and days of reaction had a less important influence on the parameters measured. While anhydrous NH₃ was most effective in improving IVDMD and IVOMD of maize stover, aqueous NH₄OH had a similar effect in increasing IVDMD and IVOMD of rice and wheat straws and urea + urease was the least effective but promising. Highest responses in IVDMD and IVOMD were obtained with rice straw, followed by wheat straw and, lastly, maize stover.In a second experiment maize stover which was treated with aqueous NH₄OH at 0, 25 and 50 g NH₃/kg DM at two moisture levels of 20 and 40% was given to Black Headed Persian rams. Digestibility of DM and OM and voluntary feed intake were improved significantly (P < 0.01) by ammonia treatment and there was also a significant (P < 0.01) response to increasing moisture levels.     

Microbial Fermentation of Rice Straw: Nutritive Composition and In Vitro Digestibility of the Fermentation Products

Rice straw was fermented with Cellulomonas sp. and Alcaligenes faecalis. Microbial cells and undigested residue, as well as chemically treated (NaOH or NH₄OH) and untreated straws, were analyzed for nutrient composition and in vitro digestibility. In a typical fermentation, 75% of the rice straw substrate was digested, and 18.6% of the total substrate weight that disappeared was recovered as microbial protein. The microbial cell fraction was 37% protein and 5% crude fiber; the residue was 12% protein and 45% crude fiber. The microbial protein amino acid profile was similar to alfalfa, except for less cysteine. The microbial cells had more thiamine and less niacin than Torula yeast. In vitro digestibility of the microbial protein was 41.2 to 55%; that of cellulose was 52%.     

Pilot-scale semisolid fermentation of straw.

Semisolid fermentation of ryegrass straw to increase its animal feed value was successfully performed on a pilot scale. The pilot plant, which could handle 100 kg of straw per batch, was designed so that all major operations could take place in one vessel. The straw was hydrolyzed at 121 degrees C for 30 min with 0.5 N H2SO4 (7:3 liquid:solid), treated with ammonia to raise the pH to 5.0, inoculated with Candida utilis, and fermented in a semisolid state (70% moisture). During fermentation the straw was held stationary with air blown up through it. Batch fermentation times were 12 to 29 h. Semisolid fermentation did not require agitation and supported abundant growth at 20 to 40 degrees C even at near zero oxygen tensions. Fermentation increased the protein content, crude fat content, and in vitro rumen digestibility of the straw.     

Pilot-scale semisolid fermentation of straw

Semisolid fermentation of ryegrass straw to increase its animal feed value was successfully performed on a pilot scale. The pilot plant, which could handle 100 kg of straw per batch, was designed so that all major operations could take place in one vessel. The straw was hydrolyzed at 121 degrees C for 30 min with 0.5 N H2SO4 (7:3 liquid:solid), treated with ammonia to raise the pH to 5.0, inoculated with Candida utilis, and fermented in a semisolid state (70% moisture). During fermentation the straw was held stationary with air blown up through it. Batch fermentation times were 12 to 29 h. Semisolid fermentation did not require agitation and supported abundant growth at 20 to 40 degrees C even at near zero oxygen tensions. Fermentation increased the protein content, crude fat content, and in vitro rumen digestibility of the straw.     

Ammoniation of wheat straw and native grass hay during baling of large round bales

Wheat straw and native grass hay were treated with anhydrous ammonia during baling with a large round baler. In Experiment 1, ammonia (3.2 and 7.1% w/w of straw DM) was applied by use of a Cold-flow Converter to wheat straw that either had not been sprayed or had been sprayed with one of two rates of water as it passed over the pick-up frame of the baler. Straw water concentrations immediately after baling were 13.8 and 23.8%, respectively, for the low and high rates of water application. Straw water concentrations were about 12 percentage units lower than anticipated, and indicate that water penetration of the hard cuticular surface of the straw was low. Treatment with 3.2% ammonia of straw not sprayed with water increased the crude protein content from 3.2 to 5.7% immediately after baling. However, none of the ammonia-nitrogen (NH₃-N) was retained 45 days after baling, and dry matter digestibility in vitro (IVDMD) of the straw was not increased. Straw that was treated with low levels of both ammonia and water contained 6.0% crude protein after storage, and IVDMD increased 27% (i.e., 36.7 vs. 28.9%; P < 0.001). Retention of NH₃-N after storage ranged from ?1.4 (low level of ammonia and no added water) to 14.8% (low level of both ammonia and water) and was increased (P < 0.001) by added water at the low level of ammonia application.The effects of crimping wheat straw during baling and addition of a surfactant (0.2% v/v) to aqua-ammonia on crude protein content, retention of NH₃-N and the IVDMD of straw were studied in Experiment 2. Water content of ammoniated straw in Experiment 2 (ca.14%) was similar to that of straw sprayed with the low level of water in Experiment 1. Crimping did not visibly disrupt the surface of the straw, nor affect crude protein content or IVDMD. Addition of surfactant to the aqua-ammonia increased (P < 0.01) the crude protein content after storage of non-crimped and crimped straw, respectively, by 0.3 and 1.5 percentage units (P < 0.05 for crimping by surfactant interaction). Straw IVDMD was not increased by either crimping or addition of surfactant to the aqua-ammonia. Retention of NH₃-N after storage, which ranged from 26 to 49%, was greater than that of Experiment 1, and was attributed to the lower level of ammonia application (1.7% of straw DM). Native grass hay readily adsorbed aqua-ammonia. Water content of the hay was increased from 12.2 to 28.7%, and the crude protein content was increased from 4.4 to 13.9% by ammoniation. The studies indicate that while ammoniation of crop residues during the baling operation is a possible means of treatment, low retention of NH₃-N remains a problem. Disruption of the hard cuticular surface of residues such as wheat straw may improve penetration of aqua-ammonia and therefore the effectiveness of treatment.     

Effect on digestibility and nitrogen content of barley straw of different ammonia treatments

The article discusses the effect on solubility in cellulolytic enzyme suspensions, digestibility in vitro and crude protein content (F × 6.25) of treating barley straw with various dosages of NH₃ (2.6–5.9%), at various temperatures (15–75°C) for various treatment times (1–14 days).An increase in any of the above factors resulted in an increased intensity of treatment, with an increase in temperature of 15°C being equal to an increased NH₃-dosage level of 1.5% or prolongation of the treatment time by a factor of 4.5Digestibility in vitro increased with increased intensity of treatment, until a maximum level was obtained. Beyond this point, an increase in NH₃-dosage, or especially in temperature, tended to decrease digestibility in vitro. Maximum digestibility could be obtained, for example, with 2.6% NH₃, 62°C and 4 days incubation, or 5.9% NH₃, 30°C and 3–7 days incubation.Likewise, both solubility in cellulolytic enzyme suspensions and crude protein content increased with increased intensity of treatment, up to a certain level. Thereafter, increased dosing with NH₃, higher temperatures or longer incubation times had little or no effect. However, maximum values were obtained with a greater intensity of treatment than the maximum digestibility in vitro, and no tendency towards decreased values was observed.Increased enzyme solubility, beyond that corresponding to maximum digestibility in vitro, was accompanied by an increased rate of fermentation and a decreased content of neutral detergent fibre.Treatment with heat (100°C) and pressure after incubation, to simulate pelleting before evaporation of surplus NH₃, was also investigated. Only after the lowest incubation temperatures, however, was there an obvious tendency towards increased digestibility. The enzyme solubility was, on the other hand, very obviously increased. Crude protein content was also slightly increased by the heat- and pressure-treatment.     

Utilization of alkali-treated and neutralized wheat straw-based rations for growing goat kids

Six groups of six goat kids were fed individually for 168 days with wheat straw given various treatments: (1) control; (2) 33 g NaOH/kg straw; (3) 80 g NaOH/kg, partly neutralized with mineral acids; (4) mineral control for 80 g NaOH/kg; (5) 120 g NaOH/kg, partly neutralized with mineral acids, and (6) mineral control for 120 g NaOH/kg straw. The average weight gain was significantly superior (P< 0.05) and the efficiency of dry matter (DM) and energy utilization was the highest with the 80 g NaOH/kg straw treatment. This treatment also gave significantly higher (P<0.05) digestibility of DM, organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF), nitrogen-free extract (NFE) and hemicellulose than the control and 33 g NaOH/kg straw treatments. Increasing levels of alkali decreased (P<0.05) the digestibility of crude protein (CP) and ether extract (EE). Digestible energy and nitrogen-corrected metabolisable energy (ME_n) (as a percentage of gross energy (GE)) were maximal with 80 g NaOH/kg. The pH value of rumen liquor was the same for the control and the 33 g NaOH/kg and 80 g NaOH/kg treatments, but significantly increased (P<0.05) with the 120 g NaOH/kg straw treatment. The mean values for rumen ammonia nitrogen (NH₃ -N) were the same for the control, the 33 g NaOH/kg, and mineral controls for 80 and 120 g NaOH/kg treatments, but 80 g NaOH and 120 g NaOH/kg straw gave significantly lower values. It is suggested that by partially neutralizing the residual alkali, 80 g NaOH/kg straw can give higher efficiency of energy utilization for growth and digestibility of nutrients compared with 33 g NaOH/kg or the untreated control group, and the extensive use of treated straw in the diets of animals of which a rapid rate of production is not demanded, may be advantageous.     

Cellulose Fermentation: Effect of Substrate Pretreatment on Microbial Growth

The effects of chemical, physical, and enzymatic treatments of rice straw and sugarcane bagasse on the microbial digestibility of cellulose have been investigated. Treatment with 4% NaOH for 15 min at 100 C increased the digestibility of cellulose from 29.4 to 73%. Treatment with 5.2% NH₃ could increase digestibility to 57.0% Treatments with sulfuric acid and crude cellulase preparation solubilized cellulose but did not increase the digestibility. Grinding or high-pressure cooking of the substrate had little effect on increasing the digestibility of cellulosic substrates by the Cellulomonas species.     

Extraction of hemicellulose from ryegrass straw for the production of glucose isomerase and use of the resulting straw residue for animal feed

The hemicellulose fraction of ryegrass straw was extracted with NaOH and used for the production of glucose isomerase by Streptomyces flavogriseus. The level of hemicellulose extracted increased proportionately with increasing NaOH concentration up to about 4%, then the rate of increase slowed down. Hemicellulose extraction was facilitated by the combined application of heat and NaOH. Approximately 15% hemicellulose (12% as pentosan) could be obtained by treating straw with 4% NaOH for either 3 hr at 90°C or 24 hr at room temperature. The highest level (3.04 units/ml culture) of intracellular glucose isomerase was obtained when the organism was grown at 30°C for two days on 2% straw hemicellulose. The organism also produced a high yield of glucose isomerase on xylose or xylan. The NaOH-treated straw residue, after removal of hemicellulose, had approximately 75% higher digestibility and 20% higher feed efficiency for weanling meadow voles than untreated straw. Thus, the residue could be used as animal feed. A process for the production of glucose isomerase and animal feed from ryegrass straw was also proposed.     

The growth conditions of cephalosporium eichhorniae for the conversion of starch substrates to protein

The protein synthesis by Cephalosporium eichhorniae on substrates containing starch was evaluated at different pH, moisture content, ammonium sulphate and potassium dihydrogen phosphate supplementation. The optimum pH level was about 4.2 and the moisture content 65%. The optimum level of supplementation of medium containing sweet potato substrate with (NH₄)₂SO₄ was smaller than that for cassava substrate (5.2 g/l < 6.7 g/l in submerged culture, and 4.0% < 5.2% in solid state fermentation). The total crude protein yields were about 7.6 g/l for submerged cultures and 12% DM for solid state fermentations.     

Evaluation of chemical pretreatment for enzymatic solubilization of rice straw

Summary Rice straw was treated with NaOH, peracetic acid (PA), and sodium chlorite (NaClO₂). Quantitative changes in the composition of the treated straw, crystallinity of the treated straw and extracted cellulose, and susceptibility of the treated straw to Trichoderma reesei cellulase were studied. The alkali treatment resulted in a remarkable decrease in hemicellulose as well as lignin. Consequently, the recovery of residual straw after NaOH treatment was lowest among the three chemical reagents evaluated. The treatment with PA or NaCIO₂ resulted in a slight loss in hemicellulose and cellulose in the straw. The three chemical treatments caused little or no breakdown of the crystalline structure of cellulose in the straw. The treated straw was solubilized with the culture filtrate of T. reesei. The degree of enzymatic solubilization relative to the amount of residual straw was 69% after treatment with 0.25 N NaOH, 42% after treatment with 20% PA, and 50% after treatments with NaClO₂ (twice). The degree of enzymatic solubilization relative to the amount of the untreated straw, however, was 30% after treatment with 0.25 N NaOH, 32% after treatment with 20% PA, and 37% after treatments with NaClO₂ (twice).     

Pretreatment of cellulosic wastes to increase enzyme reactivity

The enzymatic hydrolysis of cellulose to glucose is generally a slow reaction. Different pretreatments, such as ball milling to a ?200 mesh or swelling in 1–2% NaOH are reported to increase the reactivity considerably. In this work a fiber fraction from cattle manure was treated in an autoclave for 5–30 min at temperatures ranging from 130–200°C. The reactivity of the cellulose, measured by incubating samples with a commercial cellulase preparation for one hour at 50°C and pH 4.8, was increased by a factor of 4–6 compared to NaOH treatment and 10–12 compared to untreated fiber. The increased reaction rate is probably mostly due to an increase in cellulose availability to enzymatic attack, as structural hemicellulose is hydrolyzed and removed during the treatment. Sugars, produced by hemicellulosis, hydrolysis, will react further to give caramelization products. These side reactions were shown to be suppressed by short treatment times. The treated fiber could support growth of a mixed culture of Trichoderma viride and Candida utilis only after washing, indicating the formation of water soluble inhibitory products during treatment. The treatment with high-temperature steam can probably be used also with other cellulosic materials to increase reactivity. This may be an attractive way to prepare low-valued wastes such as manure fibers, straw, stalks, or corn cobs for fermentation processes to increase the protein content or for use directly as ruminant animal feed.     

Effect of chemical treatments on the degradability of cotton straw by rumen microorganisms and by fungal cellulase

Three different chemical treatments—sulfur dioxide, ozone, and sodium hydroxide—were applied on cotton straw, and the effect on cell-wall degradability was assessed by using rumen microorganism and Trichoderma reesei cellulase. Sulfur dioxide (applied at 70°C for 72 h) did not change the lignin content of cotton straw but reduced the concentration of hemicellulose by 48%. Ozone exerted a dual effect, both on lignin (a 40% reduction) and hemicellulose (a 54% decrease). The treatment with NaOH did not solublize cell-wall components. The in vitro organic matter digestibility with rumen fluid of cotton straw was increased significantly by ozone and SO₂ treatments, by 120% and 50%, respectively, but not by NaOH. T. reesei cellulase was applied on the chemically pretreated cotton straw at a low level (6 filter paper U/g straw, organic matter), and the release of reducing sugars was determined. The highest level of reducing sugars (30.6 g/100 g organic matter) was obtained with the O₃-cellulase combination, which solubilized 64% of the cellulose and 88% of the hemicellulose. the SO₂- and the NaOH-pretreated cotton straw were hydrolyzed by T. reesei cellulase to the same extent (21 g reducing sugars/100 g organic matter). The rumen fluid digestibility of the enzymatic ally hydrolyzed straw was not increased further over the effect already obtained with the chemical pretreatments. However, the fermentability of the combined treatments was increased markedly. In the O₃-cellulase-treated cotton straw, 83% of the rumen fluid digestible material consisted of highly fermentable components. Although ozone proved to be the most potent pretreatment for enzymic saccharification in this study, the absolute result was modest. The limited effect of the combined O₃-cellulase treatment was probably associated with the pretreatment limitations, but not with the enzyme level. Based on the differential response of the chemically treated cotton straw to attack by rumen microorganisms on the one hand, and by T. reesei cellulase on the other hand, a hypothesis has been suggested as to the location of lignin and hemicellulose in the cellwall unit of cotton straw.     

The feeding value for ruminants of straw and wholecrop barley and oats treated with anhydrous or aqueous ammonia or urea

Ammonia-treated or untreated barley straw supplemented with urea was given as the only feed to two groups of Friesian heifers weighing approximately 550 kg. The digestibility of dry matter (DM) was 58.8 and 49.9%, daily feed intake was 5.88 and 3.87 kg and daily liveweight change was +324 and -447 g for the ammonia-treated and control barley straw diets, respectively.Anhydrous or aqueous ammonia (NH₃) was injected into large round straw bales covered with plastic. The rates of degradation of barley straw in nylon bags and digestibility in vivo were the same for both ammonia treatments. The distribution of N in the bales was also similar and uniform with both treatments. No differences were recorded in the rate of degradation in nylon bags if the plastic was removed 2 or 8 weeks after treatment.Anhydrous or aqueous ammonia or isonitrogenous amounts of urea were injected into large round bags containing whole-crop barley or oats collected with a forage harvester. The digestibility of starch by steers was about 92% for ammonia-treated samples and 78% for the urea-treated samples. Urea and ammonia efficiently preserved the whole-crop materials but untreated control samples and samples treated with NaOH deteriorated during storage.     

Complete nutrient composition of commercially raised invertebrates used as food for insectivores

A variety of invertebrates are commonly fed to insectivorous animals by both zoos and hobbyists, but information as to the nutrient composition of most commercially raised species is limited. Adult house crickets, house cricket nymphs (Acheta domesticus), superworms (Zophobas morio larvae), giant mealworm larvae, mealworm larvae and adult mealworms (Tenebrio molitor), waxworm larvae (Galleria mellonella), and silkworm larvae (Bombyx mori) were analyzed for moisture, crude protein, crude fat, ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), minerals, amino acids, fatty acids, and vitamins. Earthworms (Lumbricus terresstris) were analyzed for moisture, crude protein, crude fat, ash, ADF, NDF, minerals, amino acids, and vitamins A and D₃. Proximate analyses were variable, with wide ranges found for moisture (57.9–83.6%), crude protein (9.3–23.7%), crude fat (1.6–24.9%), ADF (0.1–7.4%), NDF (0.0–11.5%), and ash (0.6–1.2%). Energy content ranged from a low of 674 kcal/kg for silkworms to 2,741 kcal/kg for waxworms.Using an amino acid scoring pattern for rats, the first limiting amino acid for all invertebrates tested was the total sulfur amino acid methionine+cystine. Deficiencies by nutrient (% of samples deficient vs. NRC requirements for rats on a dry matter (DM) basis) were as follows: calcium (100%), vitamin D₃ (100%), vitamin A (89%), vitamin B₁₂ (75%), thiamin (63%), vitamin E (50%), iodine (44%), manganese (22%), methionine‐cystine (22%), and sodium (11%). Deficiencies by invertebrate species (number of nutrients deficient vs. the NRC requirements for rats on a DM basis) were as follows: waxworms (9), superworms (8), giant mealworm larvae (7), adult mealworms (6), mealworm larvae (5), adult house crickets (4), house cricket nymphs (4), silkworms (4), and earthworms (4). These data provide a basis for determining nutrient intake of captive insectivores, and will aid in the development of gut‐loading diets to provide captive insectivorous animals with appropriate levels of necessary nutrients. Zoo Biol 21:269–285, 2002. © 2002 Wiley‐Liss, Inc.     

White-rot fungal conversion of wheat straw to energy rich cattle feed

In order to improve the digestibility and nutrient availability in rumen, wheat straw was subjected to solid state fermentation (SSF) with white-rot fungi (i.e. Pleurotus ostreatus and Trametes versicolor) and the fermented biomass (called myco-straw) was evaluated for biochemical, enzymatic and nutritional parameters. The fungal treatment after 30 days led to significant decrease (P < 0.05) in cell wall constituents viz, acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and cellulose to the extent of 35.00, 38.88, 45.00, 37.48 and 37.86%, respectively in P. ostreatus fermented straw, while 30.04, 33.85, 39.90, 31.29 and 34.00%, respectively in T. versicolor fermented straw. However, maximum efficiency of fermentation in terms of low carbohydrate consumption per unit of lignin degradation, favoring cattle feed production was observed for P. ostreatus on the 10th day (17.12%) as compared with T. versicolor on the 30th day (16.91%). The myco-straw was found to contain significantly high (P < 0.05) crude protein (CP; 4.77% T. versicolor, 5.08% P. ostreatus) as compared to control straw (3.37%). Metabolizable energy (ME, MJ/kg DM), percent organic matter digestibility (OMD) and short chain fatty acids (SCFAs; mmol) production also increased considerably from control straw (4.40, 29.91 and 0.292) to a maximum up to P. ostreatus fermented straw (4.92, 33.39 and 0.376 on 20th day) and T. versicolor fermented straw (4.66, 31.74 and 0.334 on 10th day), respectively. Moreover, the myco-straw had lower organic carbon and was rich in nitrogen with lower C/N ratio as compared to control wheat straw. Results suggest that the fungal fermentation of wheat straw effectively improved CP content, OM digestibility, SCFAs production, ME value and simultaneously lowered the C/N ratio, thus showing potential for bioconversion of lignin rich wheat straw into high energy cattle feed.     

Influence of feeding sunflower seed and meal protected against ruminal fermentation on ruminal fermentation,bacterial composition and in situ degradability in sheep

ABSTRACT

The effects of treating sunflower seed (SS) and meal (SM), as well as of a mixture of both feeds (SSM; 45:55) with a solution of malic acid (1 M; 400 ml/kg feed) and heating for protection against ruminal degradation were studied. Four rumen-fistulated sheep were fed two mixed diets composed of oat hay and concentrate (40:60) and differing only in the concentrate, that contained either a mixture of untreated SS and SM (control diet) or treated SS and SM (MAH diet). A crossover design with two 24-d experimental periods was used, and each period included 10 d of diet adaptation, 9 d for in situ incubations of SS, SM and SSM, and 5 d for measuring ruminal fermentation characteristics and rumen emptying. From day 6 onwards a solution of (¹⁵NH₄)₂SO₄ was continuously infused into the rumen of each sheep to label ruminal bacteria. Feeding the MAH diet did not affect either ruminal pH or concentrations of total volatile fatty acids and NH₃-N, but decreased (p ≤ 0.01) the molar proportions of acetate and propionate and increased those of butyrate (p< 0.001). Organic matter and lipid contents of ruminal bacteria were lower whereas both N content and ¹⁵N enrichment were greater (p ≤ 0.05) in MAH-fed sheep. The in situ effective degradability (ED) of different fractions of SS, SM and SSM were calculated from the ruminal rates of particle comminution and passage, and values were corrected for microbial contamination. The MAH treatment decreased the ED of most fractions for all feeds and increased the supply of by-pass crude protein (CP) by 19.1% and 120% for SS and SM, respectively, and that of fat by 34% for SS. The MAH treatment also increased the in vitro intestinal digestibility of the by-pass CP for both SS (from 60.1% to 75.4%) and SM (from 83.2% to 91.0%). The simultaneous heating of both feeds (SSM) reinforced the protective effect of the MAH treatment and increased the by-pass CP without altering its intestinal digestibility, increasing the intestinally digested CP content by 16.8% compared with the value estimated from the results obtained for MAH-treated SS and SM incubated independently. These results indicate that the MAH treatment was effective to protect sunflower protein against rumen degradation and increased its intestinal digestibility.