Kg Of Rice Straw Research Articles

Transcriptomic Analysis of Newborn Hanwoo Calves: Effects of Maternal Overnutrition during Mid- to Late Pregnancy on Subcutaneous Adipose Tissue and Liver.

This study investigated the transcriptomic responses of subcutaneous adipose tissue (SAT) and liver in newborn Hanwoo calves subjected to maternal overnutrition during mid- to late gestation. Eight Hanwoo cows were randomly assigned to control and treatment groups. The treatment group received a diet of 4.5 kg of concentrate and 6.5 kg of rice straw daily, resulting in intake levels of 8.42 kg DMI, 5.69 kg TDN, and 0.93 kg CP-higher than the control group (6.07 kg DMI, 4.07 kg TDN, and 0.65 kg CP), with respective NEm values of 9.56 Mcal and 6.68 Mcal. Following birth, newly born calves were euthanized humanely as per ethical guidelines, and SAT and liver samples from newborn calves were collected for RNA extraction and analysis. RNA sequencing identified 192 genes that were differentially expressed in the SAT (17 downregulated and 175 upregulated); notably, HSPA6 emerged as the most significantly upregulated gene in the SAT and as the singular upregulated gene in the liver (adj-p value < 0.05). Additionally, differential gene expression analysis highlighted extensive changes across genes associated with adipogenesis, fibrogenesis, and stress response. The functional enrichment pathway and protein-protein interaction (PPI) unraveled the intricate networks and biological processes impacted by overnutrition, including extracellular matrix organization, cell surface receptor signaling, and the PI3K-Akt signaling pathway. These findings underscore maternal overnutrition's substantial influence on developmental pathways, suggesting profound cellular modifications with potential lasting effects on health and productivity. Despite the robust insights that are provided, the study's limitations (sample size) underscore the necessity for further research.

Effects of mid-to-late prepartum feed supplementation in Hanwoo beef cows on their performance, blood metabolites, and the carcass characteristics and metabolites of their neonatal calves

IntroductionThis study aimed to evaluate the implications of supplementary nutrition during the mid-to-late pregnancy on various parameters in Hanwoo cows and their subsequent neonatal calves.Materials and methodsEight Hanwoo cows in their first parity were divided into two groups. The control group (C, 100%) received 3kg of concentrate and 5kg of rice straw throughout the pregnancy period, while the treatment group (T, 150%) increased their diet during mid-to-late pregnancy. Both performance assessments and blood metabolite analyses were performed for the pregnant cows. Neonatal calves were subjected to morphometric evaluations, blood sampling, and detailed morphometric analyses of carcasses and gastrointestinal components.ResultsPerformance indices of the cows showed that both Pregnancy Period (PregP) and Body Condition Score (BCS) were significantly improved with supplemental feeding (p &amp;lt;0.05). Improvements in Body Weight (BW) and Feed Conversion Ratio (FCR) were not statistically significant. Blood metabolite analysis for the cows revealed decreased levels of triglycerides (TGLate), non-esterified fatty acids (NEFALate), and progesterone (P4Late), with a notable increase in glucose (GluLate) levels (p &amp;lt;0.01). In the neonatal calves, anatomical metrics of the gastrointestinal tissues showed increased Omasum Width (OmasWdth) values in the supplemented group (p =0.053). There was significant increase of papillae and villus lengths in the rumen and small intestine (p &amp;lt;0.01 and p &amp;lt;0.05, respectively). Morphometric evaluations displayed longer body lengths (BLnth) and larger chest width (ChestWdth) in the treated calves (p &amp;lt;0.05 and p &amp;lt;0.01, respectively). Carcass characteristics showed no substantial variations between the groups, while blood analysis in the calves revealed decreased GPT levels in the nutritionally supplemented group (p&amp;lt;0.05).DiscussionThe findings indicate that supplementing the diets of Hanwoo cows during mid-to-late pregnancy leads to significant changes in select maternal blood metabolites and influences specific anatomical and morphometric features in neonatal calves, all without significant shifts in carcass attributes.

Selection of protic ionic liquids for the improved production of butanol from rice straw

Biomass pretreatment with protic ionic liquids (PILs) has been proved as an economically attractive method to enhance saccharification yield. This work evaluated the use of six PILs -based on acetate and hydrogen sulfate anions - using water as cosolvent for processing a high solid loading of rice straw (RS). Among the investigated PILs, the most promising results were obtained by 2-hydroxyethylammonium acetate [MEOA][OAc] containing 20 %w/w water, achieving 87.3 % of glucose and 68.6 % of xylose yield, respectively, and 98.3 % of delignification at 150 °C for 2 h with 15 %w/w solid loading. Five recovery and reuse cycles were successfully performed with [MEOA][OAc], obtaining a delignification degree of 69.5 % after the fifth reuse. Process viability was evaluated by enzymatic hydrolysis followed by acetone-butanol-ethanol (ABE) fermentation using Clostridium beijerinckii. Similar saccharification yields (89.9 ± 6.8 % glucose and 71.5 ± 4.7 % xylose) and butanol production (7.3 ± 0.1 g/L, 81.7 ± 1.7 g butanol per kg of RS) were achieved for fresh and recycled [MEOA][OAc], demonstrating the feasibility of PIL reuse. This study showed the potential of [MEOA][OAc] as a cost-effective pretreatment agent for rice straw valorization into an advanced biofuel such as butanol.

Comparison of Fodder Species with or without Nutrient Supplementation for Paddy Straw-based Dairy Cattle Production in Hills of Nepal

Productivity of crossbred dairy cattle in the milk production pockets of Nepali hills are considerably low due to their severe undernourishment in the paddy straw-based feeding regimes. An experiment was carried out at on-farm of Tanahun district in order to compare popular fodders (Ficus semicordata cv. Montana S.M. Amatya and Pennisetum purpureum K. Schumach. cv Mott) with and without nutrient supplementation via the urea-molasses-mineral block (UMMB) for milk yield, milk fat content and lactometer reading. The experiment was conducted in a 2×2 factorial arrangement of Completely Randomized Design (CRD) with 10 replications. The milking cattle of Jersey crossbred from third to fifth parities with similar milk yields and stages of lactation were taken as the experimental animals. The results of the study showed that Rai khanayo (F. semicordata) fodder performed better (p&lt;0.01) than Napier (P. purpureum) for milk yield, milk fat content, and lactometer reading. Likely, significantly enhanced (p&lt;0.05) milk yield with better fat content and lactometer reading were obtained for the UMMB supplemented group. Feeding 10 kg of F. semicordata fodder with 300 g of UMMB supplementation, 10 kg of rice straw and 2 kg of wheat bran as the daily ration improved the milk yield, milk fat content, and lactometer reading considerably (p&lt;0.05) than other treatment combinations in the farmers’ field. These simple and practical technologies can rigorously be used for the substantial improvement of the milk yield and its constituents of crossbred dairy cattle, and also for their health in the hills of Nepal.

Studies on Microwave-Assisted Pyrolysis of Rice Straw Using Solar Photovoltaic Power

Pyrolysis of one of the most underutilized lignocellulosic biomasses, namely rice straw (RS) has been carried out through solar photovoltaic (PV)-powered microwave heating with biochar as an additive for the microwave absorption. Through the preliminary studies, microwave power of 700 W and reaction times of 20 min have been chosen optimum for maximizing the yield of bio-oil, a desired product for the study along with biochar ignoring gas, due to their easy collection, storability and transportation and higher commercial value. The results of the study revealed the highest yield of bio-oil as 25% and 23% with and without additive respectively. The net energy recovery percentage was calculated to be around 71 and 56 in using solar PV and grid electricity respectively. The exergy efficiency of pyrolysis system under this study was estimated to be about 55%. The payback period of the set-up is 6.5 and 3.12 years if solar PV system and grid electricity are respectively used. The monthly income of $ 33 may be earned from the pyrolytic products such as biochar, wood vinegar and tar by pyrolysing 675 kg of RS annually (2.25 kg per day at 450 g per batch with 5 batches per day and 300 days per year). The potential of mitigating CO2 emission during the total life time of 30 years from the existing set-up is 55 tons and the earning of carbon credit is $ 1600 considering the current price of carbon credit as $ 30/ton.

Sustainable Bio-Conversion of Rice Straw Waste into High Quality Organic Fertilizer

The aim of this study is to investigate the effect of different additives including biochar, effective micro-organisms (EM), animal manure and commercial microbial inoculants on the bioconversion of rice straw. Different compost piles were constructed, and each contained 50 kg of rice straw and mixture of natural rocks to enrich the compost nutritional value. The physical, chemical and biological parameters indicating the decomposition of organic material, maturation and quality of the organic fertilizer product were investigated during the composting process. A rapid increase in compost temperature was obtained in inoculated piles. All piles reached maturation after around 42 days. All analysis of the properties of the final compost products indicated that it was in the range of the matured level and can be used as organic fertilizer without limitation. The highest decomposition rate and highest organic fertilizer quality were obtained in the pile inoculated with EM and 10% biochar compared to other treatments.

Test Performance and Economic Analysis of Straw Chopper Machine

The usage of rice straw as an alternative basic compost fertilizer is needed. Rice straw processing into compost fertilizer through stage chopper. Chopper is the size reducing stage that it is easily decomposed. The chopper processing can be done by using straw chop machine. This research aims for performance test and economic analysis. Research use descriptive analysis. The results of performance test of straw chop machine have actual capacity is 103.32±12.068 kg/h, engine efficiency is 79.59%, power requirement with load and without load are 1.1±0.067 HP and 0.698±0.109 HP, specific load 7.94 W/kg, chopper yield is 94.33±0.97%, the percentage of chopper chunks is 83.55±0.04%, engine noise level 76.6±0.5 dB, and vibration level on the framework, hopper and chopper cylinder are 18±4.9 mm/s2, 53.94±1.3 mm/s2 and 21.6±4.6 mm/s2. Based on the result of economic analysis of rice straw chop machine have the basic cost is Rp.46,159,621.- with gross income Rp.55,792,800.-/year. The breakeven point has been reached when the machine has chopped 41,078 kg of rice straw. This rice straw chopper machine has met the economic feasibility criteria of NPV>0 that is Rp.52,821,891. BC Ratio>1 with value is 1.17. IRR value> MARR interest rate (9%) with IRR 102%.

Phenolic acids derived from rice straw generate peroxides which reduce the viability of Staphylococcus aureus cells in biofilm

Phenolic acids are abundant in rice straw (Oryza sativa L.). Exploiting the high value of phenolic acids (PAs) could solve the problem of straw resource utilization. For this, PAs were extracted from rice straw to investigate their antimicrobial effect in this study. Chemical composition of PAs was analyzed and 16 compounds were identified. The yield of PAs was 11.4 ± 0.4 g from 1 kg of rice straw, and the major compounds were p-coumaric acid (46.0%w/w), ferulic acid (23.3% w/w), vanillic acid (5.7% w/w) and vanillin (1.2% w/w). It was found that PAs had a strong inhibitory effect on Staphylococcus aureus in this study. The antimicrobial activity of PAs was mainly attributed to p-coumaric acid and ferulic acid. The minimum inhibitory concentration (MIC) values of p-coumaric acid and ferulic acid were 0.6 g/L and 1.2 g/L, respectively. More importantly, the combination of the phenolic acids could provide a synergistic effect. Therefore, the MIC of PAs derived from rice straw decreased by 1.5- to 3-fold relative to the MIC of p-coumaric acid and ferulic acid used individually. From assays of metabolites, adenosine triphosphate(ATP), adenosine diphosphate(ADP), oxidized form nicotinamide adenine dinucleotide(NAD+) and reduced form nicotinamide adenine dinucleotide(NADH), oxidized form nicotinamide adenine dinucleotide phosphate(NADP+) and reduced form nicotinamide adenine dinucleotide phosphate(NADPH), and the hydroxyl radical, the stimulation of the Fenton reaction was observed, which consumed adenosine triphosphate and reduced form of nicotinamide adenine dinucleotide, increased hydroxyl radicals, resulting in oxidative damage to cells, which was similar to the common mechanism of cell death induced by bactericidal antibiotics. Confocal laser scanning microscopic and atomic force microscopic images revealed that PAs destroyed the biofilm structure, changed the morphology of cells in the biofilm, and reduced their viability, suggesting potential medical applications for PAs. This study could provide theoretical guidance for the development of a plant-based antimicrobial agent, thus promoting straw utilization in a biorefinery.

Extraction and Characterisation of Cellulose Materials from Sri Lankan Agricultural Waste

Agriculture is a key sector of Sri Lankan economy today. Sri Lanka’s main food crop is rice. Rice is cultivated mainly in two seasons in the country. Rice production is the predominant form of agriculture which occupies 0.77 million hectares of the total cultivated area in Sri Lanka. Nevertheless, generation of enormous amounts of agricultural residues such as rice straw during rice production has become inevitable According to the statistics it is revealed that one ton of rice paddy produces 290 kg of rice straw. Regardless of these large amounts, rice straw is frequently abolished by open field burning by majority of farmers. However, recent researchers have reported that rice straw burning can be lethal towards human health due to the noxious emissions which cause various forms of environmental pollution. Hence, identifying the means of generating value added products by utilisation of rice straw has become a necessity today. Rice straw is a lingo cellulosic biomass which consists of biopolymers of cellulose, hemicellulose and lignin. Cellulose is the mostly abundant organic polymer on earth that can be identified as one of the most demanded advanced materials in engineering applications such as bio composites production. Therefore, developing a method to isolate cellulose from rice straw would be a convenient means of value addition to the agricultural waste. This research work is based on developing an environmentally friendly, efficient method to synthesise cellulose from rice straws of the most frequently cultivated hybrid rice variety (BG352) in Sri Lanka. BG 352 rice variety is cultivated in most of the areas in Sri Lanka today. High purity cellulose was extracted from rice straw by the removal of non-cellulosic materials. This chemical purification process consisted of dewaxing, delignification and hemicellulose and silica removal treatments. FTIR spectroscopy was used to verify the formation of pure cellulose during the extraction process. Further, morphology of extracted cellulose was studied by SEM analysis. It revealed that isolated cellulose was mostly in the form of fibers with diameters ranging from 2-8μm. This research showed that BG352 variety averagely has 16.1 wt.% wax, 38.2 wt.% lignin, 3.9% wt. hemicellulose and 12.3 wt.% silica content. Ultimately, average cellulose yield from rice straws of BG352 variety was observed as 30 wt.%. This extraction process can be used to synthesis the cellulose from Sri Lankan agricultural waste to convert it into a value added product. Keywords: Rice straw, Agricultural waste, Cellulose, Lignocellulosic, Biopolymer

359 Effects of dietary glycerin on carcass characteristics, fatty acid profile, and volatile compounds in longissimus dorsi muscle of Korean steers

Dietary glycerol may improve beef quality by affecting glycogen content and marbling. This study was performed to evaluate the effect of a glycerin-increased diet on growth performance, carcass characteristics, chemical composition, sensory traits, fatty acid profile, and volatile compounds in longissimus dorsi muscle (LM) of beef cattle. Twenty Korean steers (647 ± 10.49 kg BW and 27 mo of age) were divided into a control diet group (n = 10) and a glycerin-increased diet group (n = 10). Diets were formulated to meet or exceed NRC (2000) requirements. The control diet, which was conventionally designed for finishing period of Korean cattle, was used in this study. For the glycerin-increased diet, the portion of molasses and distiller's dried grains with solubles in the control diet were replaced with a 3% crude glycerin with isoenergy nutrient levels (TDN = 87%, DM basis) compared with the control diet. All steers were allowed daily to receive a concentrate with the amount of 1.5% of BW and 1.0 kg of rice straw. The feeding trial was performed for 5 wk. Water was allowed ad libitum. All data were analyzed by ANOVA using GLM of SAS. Concentrate intake was 14% higher (P < 0.01) in the glycerin group compared with control group, whereas rice straw intake was not different between the 2 groups. Average daily gain and feed efficiency (G:F) were not different between the 2 groups (P > 0.05). Animals were slaughtered after the feeding trial, and LM samples were collected from hot carcasses within 2 h after slaughter and frozen for chemical analyses. The carcasses were kept at 4°C for 24 h and graded with Korean standard grading methods. Longissimus dorsi muscle samples were also collected from cold carcasses at 24 h for analysis of sensory traits. Carcass weight, LM muscle area, back fat thickness, marbling score, yield grade, and quality grade were not different between the 2 groups (P > 0.05). Contents of protein, fat, collagen, reducing sugar, and glycogen in the LM were not different between the 2 groups (P > 0.05). Sensory traits (appearance, flavor, taste, tenderness, juiciness, and overall acceptance) and percentages of fatty acids and volatile compounds in the LM were not different between the 2 groups (P > 0.05). In conclusion, the glycerin-increased diet improved feed intake, although it did not affect daily gain and feed efficiency. The glycerin-increased diet did not affect beef quality, including marbling, glycogen contents, sensory traits, and percentages of fatty acids and volatile compounds in the LM.

Biotechnological Application of Thermotolerant Cellulose-Decomposing Bacteria in Composting of Rice Straw

The main objective of this study is to investigate the potentiality of cellulase producing isolates, Bacillus licheniformis 1-1v and Bacillus sonorensis 7-1v, as microbial additives on composting of rice straw materials. Different pyramid shape piles were constructed, and each contained 80kg of rice straw and 288kg of cattle manure, with/without 5kg of feldspar supplementation (0.75%, w/w). C/N ratio was adjusted to 35.8 before microbial inoculation. The piles were inoculated with either single strain or mixed cultures. The physical, chemical and biological parameters indicating the decomposition of organic material, maturation and quality of the compost product were investigated during the composting process. A rapid increase in compost temperature was obtained in inoculated piles. Moreover, piles containing mixed inoculants exhibited longer time at high temperatures >55°C for 15 consecutive days compared to control treatments that lasted for only 5 consecutive days. The microbial inoculation had greatly reduced the composting time by 40–43% (from 89–96days to 51–58days). Additionally, it resulted in a higher decrease in the total organic carbon and carbon-to-nitrogen ratio, as well as increase in compost quality by an increase in total nitrogen, phosphorus, and potassium content. The analysis of moisture content, bulk density, pH value, electrical conductivity, phytotoxicity, and pathogenic bacterial content of the final compost products exhibited maturation and good quality of final product to be used without any limitations.

Pretreatment of rice straw by hot-compressed water for enzymatic saccharification

The primary objective of this work was to measure the maximum amount of glucose that can be produced from Thai rice straw using hot-compressed water (HCW)-pretreatment before enzymatic saccharification. The optimal HCW-pretreatment temperature and time were found to be 180 °C/2MPa for 20–30 min. However, the concentrations of the yeast inhibitors were strongly dependent on the HCW-pretreatment temperature and time. At temperatures over 180 °C/2MPa or for more than 30 min at 180 °C/2MPa in the HCW-pretreatment the combined concentration of these two inhibitors (Furfural and 5-Hydroxymethylfurfural) increased exponentially, while the glucose levels were near the maximal asymptote. At the more optimal HCW-pretreatment condition of 180 °C/2MPa for 20 min, 25±3 kg of glucose could be produced from a 100 kg of rice straw, which is potentially economically competitive with other sources

Changes of rumen pH, fermentation and microbial population as influenced by different ratios of roughage (rice straw) to concentrate in dairy steers

SUMMARYThe current study was designed to determine the effect of roughage to concentrate ratio (R : C) on rumen pH, fermentation and bacterial population in dairy steers. Four rumen fistulated dairy steers (170±20 kg) were randomly assigned according to a 4×4 Latin square design, in which the steers were fed with four dietary treatments with different R : C ratios of 0·8 : 0·2, 0·6 : 0·4, 0·4 : 0·6 and 0·2 : 0·8, respectively. All animals were kept in individual pens and received feed according to the respective R : C ratios at 0·025 body weight (BW)/d; urea-treated rice straw (prepared using 3·5 kg urea+100 kg water sprayed onto 100 kg of rice straw) was used as a roughage source. The experiment was conducted for four periods of 21 days each. During the first 14 days, feed intake was measured and the animals were then moved to metabolism crates for total urine and faecal collection for 7 days. Total dry matter intake (DMI) was similar among treatments. Energy intake increased as the proportion of concentrate in the diet increased. Apparent digestibilities of dry matter (DM), organic matter (OM) and crude protein (CP) were improved, while neutral detergent fibre (NDF) and acid detergent fibre (ADF) were reduced when the levels of concentrate increased. A decreasing ratio of R : C reduced rumen pH linearly, from 6·4 to 5·9 at 0·2 : 0·8. High levels of concentrate impacted on volatile fatty acids (VFA) molar proportions and decreased acetate (C2) linearly, while propionate (C3) was increased, leading to decreased C2 : C3 ratio. Numbers of protozoa, fungi and proteolytic bacteria were not affected by R : C ratio. Cellulolytic bacteria decreased linearly while amylolytic bacteria increased linearly with 0·60 and 0·80 concentrates. Quantitative polymerase chain reaction (qPCR) based on 16S RNA revealed thatFibrobacter succinogenesnumbers were increased when steers were fed with R : C ratio of 0·8 : 0·2. Conjugated linoleic acid (CLA)-producing bacteria, especially those ofButyrivibrio fibrisolvens, increased linearly with R : C ratios of 0·8 : 0·2 and 0·6 : 0·4, whileMegasphaera elsdenii, a lactate-utilizing bacterium and reported producer oftrans-10,cis-12 CLA increased linearly with R : C ratio of 0·8 : 0·2. In addition, microbial CP synthesis increased quadratically when steers were fed high levels of concentrate. However, the efficiency microbial N synthesis (EMNS) based on OM, truly digested in the rumen, was not affected by different R : C ratios. From the current study, it can be concluded that roughage to concentrate ratio of 0·4 : 0·6 had positive effects for the creation of healthy rumen (rumen pH and ecology), and improved energy intake and rumen fermentation, particularly propionic acid and microbial protein synthesis, in dairy steers fed urea-treated rice straw as a roughage source.

Effects of supplementation of urea-molasses multinutrient block (UMMB) on the performance of dairy cows fed good quality forage based diets with rice straw as a night feeding

An experiment was conducted to evaluate the effects of nitrogen supplementation through urea-molasses multinutrient block (UMMB) on the performance of dairy cows fed good quality forage based diets with rice straw as a night feeding. A total of 10 multiparous crossbred dairy cows in their early lactation were grouped into two categories based on their breed, parity, body weight, milk yield, milk fat and protein contents and daily fed a chopped CO-3 grass (Pennisetum purpureum × Pennisetum americanum; hybrid Napier) ad-libitum, 1 kg of dairy cow concentrate feed during the day time and 5 kg of rice straw (dry matter basis) at night as the basal diet (control) for 5 wk. In addition to the basal diet, the treatment group received 300 g of crushed UMMB daily throughout the experimental period. Cows were milked twice daily and the milk yields were recorded. Milk and feed samples were collected weekly for chemical analysis. Supplementation of UMMB had no significant effects (p>0.05) on straw intake, daily milk yield, contents and yields of milk constituents such as milk fat, protein, lactose and solids-non-fat. In addition, milk urea nitrogen content were not affected (p>0.05) by UMMB supplementation. However, numerical increments in all the parameters measured were observed during the study in cows fed diets supplemented with UMMB. It can be concluded that nitrogen supplied through UMMB had no effects on production performances of dairy cows in this study.

Starch source in high concentrate rations does not affect rumen pH, histamine and lipopolysaccharide concentrations in dairy cows

The replacement of ground corn by cassava meal on rumen pH, lipopolysaccharide (LPS) and histamine concentrations under typical Thai feeding conditions (high concentrate diets and rice straw as the sole source of roughage) was investigated. Four rumen-fistulated crossbred Holstein, non-pregnant, dry cows were randomly assigned to the four experimental rations in a 4×4 Latin square design with 21-d periods. Each period consisted of a 14-d run-in/wash out period, followed by a 7-d experimental period. During the run-in/wash out period, the cows were offered 5.4kg DM of concentrate containing 4.6% cassava meal and rice straw was provided ad libitum. During the 7 day of each experimental period, cows were offered 10.5kg DM of concentrate containing either 4.6% or 18.3% or 32.4% or 46.2% cassava meal and 1.5kg of rice straw. Irrespective of dietary treatments, rumen total VFA and lactate concentrations were significantly affected by sampling day, which were significantly higher on day 1 versus days 3 and 7 of the experimental periods. Mean postprandial rumen pH was reduced to values <5.6 for at least 6h on days 3 and 7 of each experimental period. However, the relationship between rumen pH, total VFA and lactate concentrations was not straight forward. Rumen LPS and histamine concentrations were not affected by either ground corn or cassava mean, but values significantly increased from day 1 to 7 of each experimental period with the values ranging from 10.3×103 to 40.3×103EU/ml and 11.5 to 33.2μM, respectively. Both plasma LPS and histamine concentrations were below the detection limit. It can be concluded that the amount of concentrate but not the replacement of ground corn by cassava meal, affect rumen pH, rumen fluid concentrations of total volatile fatty acids, lactate, histamine and LPS. Irrespective of the dietary treatments, the results suggested that a low rumen pH is associated with an increase in rumen histamine and LPS concentration, which is not accompanied by an increase in plasma histamine or LPS concentration.

Sequestration of Holotrich Protozoa in the Reticulo-Rumen of Cattle

Studies were carried out to determine the means by which holotrich protozoa can maintain their numbers within the rumen against the washout effect associated with the flow of ingesta. When a diet composed of 2 kg of concentrate and 1.5 kg of rice straw was fed to Holstein cows, about a fourfold increase in holotrich numbers per ml of rumen fluid was observed within 1 h after the commencement of feeding, and an abrupt decrease followed. This fluctuation in numbers was not related to the time of feeding. A sole feeding of 2 kg of concentrate had almost the same effect on the holotrichs as a sole feeding of 1.5 kg of rice straw. Administration of either 2 kg of concentrate or 1.5 kg of rice straw through the rumen fistula caused similar changes, though the extent of response to the former was greater than that to the latter. The administration of either 0.7 kg of starch or 0.2 kg of glucose through the fistula had a relatively minor effect on the holotrich population. Addition of rice straw to 0.5 kg of concentrate increased the change in numbers, but its addition had little, if any, effect when 1 kg of concentrate was fed. These results suggested that the fluctuation in holotrich numbers was related not only to the nature or component of feed but also to other factors such as the quantity or volume of a diet and the act of ingesting feed. Increasing the number of feedings up to eight times per day at 3-h intervals caused a decrease in the peak heights of holotrich numbers per milliliter of rumen fluid. A thick protozoal mass which primarily consisted of holotrichs was found on the wall of the reticulum of Holstein steers slaughtered after overnight starvation. These findings suggest that holotrichs would usually sequester on the reticulum wall and migrate into the rumen only for a few hours after feeding, and that this mode of behavior would be essential for holotrichs to maintain their population within the rumen of cattle. Possible mechanisms of the migration are also discussed.