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1.
A quantitative method of analysis for 2-aminoethylphosphonic acid (AEP) was developed using reverse-phase HPLC. The detection limit for AEP was 15 nM, and the detector response (peak area) was linear from AEP levels up to 100 microM (R = .99). Mean recovery of AEP added to strained ruminal fluid from faunated sheep was 98.2%. When AEP was added to a fermentation mixture at a concentration of 22.6 micrograms/ml, 78% disappeared during a 24-h incubation. 2-Aminoethylphosphonic acid was readily detected in preparations of mixed ruminal ciliate protozoa as well as in mixed and pure strains of ruminal bacteria, feedstuffs, and ruminal fluid and duodenal digesta from defaunated sheep. The occurrence of AEP in feed and bacterial hydrolysates was confirmed by organic phosphorus analyses. The concentration of AEP in mixed ruminal protozoa was three times greater than its concentration in mixed ruminal bacteria (4,304 vs 1,383 micrograms/g DM, respectively). The AEP values for pure ruminal bacterial cultures ranged from 733 micrograms/g DM in Bacteroides succinogenes B21a to 1,166 micrograms/g DM in Butyrivibrio fibrisolvens H17c. Ruminal fluid and duodenal digesta from defaunated sheep contained AEP concentrations of 30 micrograms/ml and 90 micrograms/g DM, respectively. The concentration of AEP in feedstuffs ranged from 25 micrograms/g DM in wheat straw to 263 micrograms/g DM in oats. Because AEP occurrence is not limited to ruminal ciliate protozoa, it is of little value as a marker for protozoal presence in or passage out of the rumen.  相似文献   

2.
The effects of source and level of dietary NDF on intake, ruminal digestion in situ, ruminal fermentation, and total tract digestion were evaluated in Hereford steers using a replicated 5 x 5 Latin square design. Diets contained 62 to 64% TDN and included 1) 80% control concentrate (contained pelleted ground grains) and 20% timothy hay (traditional diet), 2) 80% control concentrate and 20% alfalfa cubes, 3) 90% control concentrate and 10% cubes, 4) a completely pelleted diet using corn cobs as the primary NDF source, and 5) 80% textured (rolled instead of ground grains) concentrate and 20% hay. Dry matter intake differed (P less than .05) between the traditional and cube diets due to limited acceptance of alfalfa cubes. Increased (P less than .05) ruminal osmolality, total VFA, and NH3 N and lower (P less than .01) ruminal pH in steers fed corn cob and cube diets relative to steers fed the traditional diet were due to preferential consumption of concentrate over supplemental roughage and the resultant rapid fermentation of concentrates. Potentially degradable DM in the traditional diet exceeded (P less than .06) all other diets, resulting in the increased (P less than .10) extent of DM disappearance despite a slower (P less than .05) rate of DM disappearance. Rate of NDF disappearance and all in situ starch disappearance parameters were similar between the traditional, corn cob, and cube diets. All ruminal digestion parameters involving NDF disappearance were similar between hay diets and between cube diets, whereas rate and extent of starch disappearance differed (P less than .05) between hay diets. Although formulation of diets with different sources of dietary NDF did not affect total tract digestion of nutrients, nutrient availability and ruminal fermentation were altered due to dietary differences in sources of dietary NDF and preferential selection of feedstuffs by steers.  相似文献   

3.
N tau-methylhistidine (NMH) concentrations were determined in acid hydrolysates of 12 common feedstuffs for ruminants, and duodenal digesta from steers fed alfalfa haylage and high-moisture corn. For six species of grass hays, NMH concentrations ranged from nondetectable (ND; less than .1 nmol/g dry matter) to .6 nmol/g dry matter. Two legume hays had NMH concentrations of .9 and 2.0 nmol/g dry matter, respectively. For corn silage, high-moisture corn, beet pulp and soybean meal, NMH concentrations were 1.3, 1.1, 1.5 and 2.2 nmol/g dry matter, respectively. Duodenal digesta NMH concentrations ranged from ND to 1.2 nmol/g dry matter. When pure NMH (1 mM) was incubated with rumen fluid in vitro for 8 h, only 14% was degraded while leucine (1 mM) was totally degraded. From the feedstuffs used in this study, results show that exogenous (dietary) NMH is not a concern in skeletal muscle protein turnover studies in cattle using urinary NMH excretion because it can be calculated that potential NMH intake from the preceding feedstuffs would be less than 1% of normal urinary excretion and that ruminal microbes are not a potential source of NMH. NMH was resistant to in vitro ruminal degradation. The in vitro ruminal NMH degradation results suggest that when feedstuffs containing at least 15 nmol/g dry matter are fed (far greater than values observed in this study) a significant proportion of urinary NMH would arise directly from exogenous sources and would invalidate the use of this technique in assessing protein turnover in cattle.  相似文献   

4.
Eight multicannulated heifers (average BW 415 +/- 34 kg) were used in a replicated 4 x 4 Latin square to evaluate fluid milk processing wash water solids (WWS) as a dietary N source. Heifers were fed corn/cottonseed hull-based diets containing soybean meal (control, 0% WWS N) or WWS replacing soybean meal at 33, 67, or 100% of supplemental dietary N. Total tract and ruminal DM and OM digestibilities decreased linearly or cubically (P less than .05) as dietary WWS N increased. Total ruminal VFA concentration (P less than .05) and propionic acid molar proportion (P less than .10) were greater in heifers fed 0 vs 100% WWS N. Heifers fed 0% WWS N had the greatest (P less than .05) ruminal ammonia concentration at all sampling times. Dietary WWS did not affect (P greater than .10) ruminal pH, fluid dilution rate, fluid flow, fluid volume, or turnover time. Total tract N digestibility decreased quadratically (P less than .10) with increasing WWS N in the diet. Supplemental WWS N did not affect (P greater than .10) flow of duodenal ammonia N or bacterial N, or efficiency of microbial N synthesis. Diets containing WWS N resulted in a cubic increase (P less than .10) in duodenal flow of essential amino acids compared with 0% WWS N; however, there were no differences in small intestinal amino acid disappearance. Data indicate that WWS can replace 33% of the soybean meal N in a corn/cottonseed hull-based diet without decreasing ruminal fermentation, fluid digesta kinetics, microbial efficiency, or small intestinal amino acid utilization.  相似文献   

5.
The effects of tallow supplementation [0% (NT) vs 7.5% (T)] and crude protein level [8.5% (LP) vs 12.0% (HP)] on ruminal fermentation, microbial protein (MCP) synthesis, digesta passage and site of digestion were estimated using yearling Angus X Simmental steers (390 kg) fitted with ruminal and T-type duodenal cannulae. Chromium-EDTA and ytterbium (Yb) chloride were used as markers of the liquid and solid phases. Passage and site of digestion data were estimated from the concentrations of Yb in the duodenal digesta and feces. Dry matter (DM) intakes were 6.8, 6.5, 6.3 and 6.6 kg/d for the NT-LP, NT-HP and T-HP diets, respectively. Ruminal ammonia concentrations (mg/100 ml) for the NT-LP, NT-HP, T-LP and T-HP diets were 1.22, 4.75, 1.05 and 3.41, respectively. Tallow decreased (P less than .05) acetate (mol/100 mol), increased (P less than .01) propionate (mol/100 mol) and decreased the total volatile fatty acid concentration. Tallow depressed apparent ruminal DM and organic matter (OM) digestibilities only on the HP diet. High protein increased ruminal DM, OM and fiber digestibilities. Tallow and LP tended to shift the site of OM digestion to the lower tract. The liquid and solid dilution rates for the NT-LP, NT-HP, T-LP and T-HP diets were 9.53, 3.37; 5.63, 3.28; 6.66, 5.10 and 6.79, 5.34%/h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
Four ruminally cannulated Holstein steers (average BW 303 kg) were used in a 4 x 4 Latin square design digestion trial to study the influence of daily cottonseed meal (CSM; 1.6 g of CP/kg of BW) supplementation time on forage intake and ruminal fluid kinetics and fermentation. Steers were housed individually in tie stalls and were fed chopped fescue hay on an ad libitum basis at 0600 and 1400. Treatments were 1) control, grass hay only (CON) and grass hay and CSM fed once daily at 2) 0600 (EAM) 3) 1000 (MAM), or 4) 1400 (PM). Ruminal NH3 N concentrations reflected a time of supplementation x sampling time interaction (P less than .05); CON steers had the lowest (P less than .05) ruminal NH3 N concentrations at all times other than at 0600, 1000, 1200, and 2400, when they did not differ (P greater than .05) from at least one of the supplemented groups. Forage intake, ratio of bacterial purine:N, rate of DM and NDF disappearance, and ruminal fluid kinetics were not influenced (P greater than .05) by supplementation time. Total ruminal VFA differed (P less than .05) between CON and supplemented steers, as well as among supplemented steers (linear and quadratic effects P less than .05). Acetate, propionate, and valerate proportions were influenced (P less than .05) by a sampling time X supplementation time interaction. Under the conditions of this study, greater peak ammonia concentrations with morning supplementation than with afternoon supplementation did not stimulate ruminal fermentation or rate of NDF disappearance.  相似文献   

7.
Wheat and potato are rich in starch but their starches differ in their rate of ruminal degradation. Kinetics of in sacco disappearance and profiles of ruminal fermentation were studied for these two concentrates in total mixed rations based on grass silage or corn silage. Wheat starch was more rapidly (34%/h) degraded by rumen microorganisms than potato starch (5%/h). The differences in starch degradation in sacco were found again in the VFA concentrations, mainly in grass silage-based diets. Overall ruminal pH, total VFA concentration, and proportions of acetate, propionate, and butyrate are more variable for wheat during the kinetic (amplitude and quickness) than for potato in grass silage-based diets. In these diets, risks of acidosis were more elevated with wheat than with potato but the VFA concentrations were also higher. These differences of fermentation profile were so reduced in corn silage-based diets that, in this case, wheat can be substituted by potato without any effect on digestion and no risk of acidosis.  相似文献   

8.
To determine the site of 3-methylindole (3MI) and indole absorption in cattle after ruminal administration of L-tryptophan (TRP), 4 Holstein steers were given 0.4 g of TRP/kg of body weight directly into the rumen through ruminal cannulas. Chromium EDTA and ruthenium phenanthroline were added to feedings of orchard grass hay twice a day for measurement of fluid and particulate flow to the duodenum, respectively. Passage of 3MI and indole (products of ruminal fermentation of TRP) to the duodenum was determined by the products of digesta flow rate and concentration in duodenal contents. Ruminal fluid, duodenal contents, and jugular blood were sampled at postdosing hours (PDH) 0, 6, 12, 18, 24, 36, and 72 for analysis of 3MI, indole, and digesta flow markers. Ruminal, duodenal, and jugular plasma concentrations of 3MI and indole peaked at PDH 12 to 24 at 152.4 and 25.9; 15.5 and 1.0; and 8.7 and 2.2 mg/L, respectively. Most 3MI and indole reaching the duodenum were associated with the particulate phase of the digesta. On a molar basis, total passage of 3MI to the duodenum during 72 hours amounted to 1.0% of the TRP dose for 3MI and 0.1% of the TRP dose for indole. Absorption of 3MI and indole in these steers was almost entirely proximal to the duodenum.  相似文献   

9.
To assess the influence of forage diets on particle size of digesta in the rumen, three ruminally fistulated steers were fed alfalfa, orchardgrass or switchgrass hays in a 3 x 3 Latin square design. Mean sieve size of ruminal digesta for alfalfa, orchardgrass and switchgrass diets was 671, 652 and 466 microns, respectively. A second experiment examined the influence of ruminal particle size on digesta passage, digestibility and intake. Four ruminally fistulated Angus-Hereford steers were given ad libitum access to different proportions of alfalfa and switchgrass in a 4 x 4 Latin square design. Either a 100% alfalfa, 50% alfalfa:50% switchgrass, 25% alfalfa:75% switchgrass or 100% switchgrass diet was offered once daily. Mean sieve sizes of the ruminal digesta of these diets responded cubically (P less than .01; 1,066, 946, 1,003 and 925 microns, respectively). Mean ruminal turnover times were 24.3, 24.8, 24.7 and 29.8 h, respectively. Dry matter intake increased linearly (P less than .10) as the proportion of legume in the diet increased; no influence of diet on DM digestibility was observed. Passage rate of dosed nylon particles 1, 3 and 5 mm in length was influenced (P less than .01) by size; however, no difference in the passage rates of the nylon particles due to diet was evident. Particle size of ruminal digesta did not respond in a linear manner to the proportion of legume in the diet. A smaller ruminal particle size was not associated with a faster turnover of digesta.  相似文献   

10.
Four diets containing 15% CP were formulated to study the effects of dietary carbohydrate and protein sources on N metabolism and carbohydrate fermentation by ruminal bacteria. Diets were supplied to eight dual-flow continuous culture fermenters during three experimental periods in a randomized complete block design. Six replications were obtained for each diet. Treatments were arranged as a 2 X 2 factorial with two carbohydrate and two protein sources. Carbohydrate sources were corn and barley and protein sources were soybean meal (SBM) and fish meal (FM). Approximately 40% of the dietary CP was derived from SBM or FM and corn or barley provided 39% of dietary DM. All diets contained 15% grass hay, 20% wheat straw, and 10.1 to 15.3% solka floc (DM basis). Interactions (P less than .05) were observed between dietary carbohydrate and protein sources, resulting in a depression of VFA production (moles/day) and digestion (percentage) of ADF and cellulose when the corn-FM diet was fed. True OM digestion (percentage) was higher (P less than .05) for SBM than for FM diets and for corn than for barley diets. Although dietary CP degradation (percentage) was higher (P less than .05) for SBM than for FM diets, non-NH3 N in the effluent (grams/day) was not different among diets due to a greater (P less than .05) bacterial N flow for SBM than for FM diets. Despite the lower amino acid (AA) intake (P less than .05) for corn than for barley diets and also for FM than for SBM diets, flows (grams/day) of total AA, essential AA (EAA), and nonessential AA (NEAA) were similar (P greater than .05) among diets. However, greater (P less than .05) total AA, EAA, and NEAA flows (percentage of AA intake) were found for corn than for barley diets and for FM than for SBM diets. It is concluded, therefore, that ruminal escape protein derived from corn or FM has a significant effect on manipulating AA leaving the ruminal fermentation.  相似文献   

11.
We used DNA probes to study dietary effects on the prokaryotic population in the rumen. Procedures used to isolate and quantify prokaryotic 16S ribosomal RNA (rRNA) from the rumen using universal and species-specific DNA probes were evaluated. In this experiment, three ruminally fistulated steers were fed orchard-grass hay, and ruminal digesta were collected at 0, 3, and 9 h after offering hay (0800). Samples of ruminal digesta were taken from the interior portion of the digesta mat and from the fluid below the mat in the dorsal rumen. Freezing (-65 degrees C) and blending samples both increased (P less than .07) the yield of 16S rRNA from ruminal digesta. Extraction of prokaryotic rRNA was greater (P less than .04) when phenol buffered with sodium acetate was used than when it was buffered with hydroxymethyl-amino-methane. Prokaryotic 16S rRNA concentration of the fluid phase was similar (P greater than .10) at 0, 3, and 9 h after offering hay. Prokaryotic 16S rRNA concentration of the mat phase increased up to the 9 h after feeding. The proportion of Fibrobacter succinogenes remained constant in both digesta phases at all times measured. From these data we concluded that DNA probes can be used to monitor bacterial population shifts in the rumen.  相似文献   

12.
The objectives of this experiment were to investigate the effects of two ruminally degradable protein (RDP) levels in diets containing similar ruminally undegradable protein (RUP) and metabolizable protein (MP) concentrations on ruminal fermentation, digestibility, and transfer of ruminal ammonia N into milk protein in dairy cows. Four ruminally and duodenally cannulated Holstein cows were allocated to two dietary treatments in a crossover design. The diets (adequate RDP [ARDP] and high RDP [HRDP]), had similar concentrations of RUP and MP, but differed in CP/RDP content. Ruminal ammonia was labeled with 15N and secretion of tracer in milk protein was determined for a period of 120 h. Ammonia concentration in the rumen tended to be greater (P = 0.06) with HRDP than with ARDP. Microbial N flow to the duodenum, ruminal digestibility of dietary nutrients, DMI, milk yield, fat content, and protein content and yield were not statistically different between diets. There was a tendency (P = 0.07) for increased urinary N excretion, and blood plasma and milk urea N concentrations were greater (P = 0.002 and P = 0.01, respectively) with HRDP compared with ARDP. Milk N efficiency was decreased (P = 0.01) by the HRDP diet. The cumulative secretion of ammonia 15N into milk protein, as a proportion of 15N dosed intraruminally, was greater (P = 0.003) with ARDP than with HRDP. The proportions of bacterial protein originating from ammonia N and milk protein originating from bacterial or ammonia N averaged 43, 61, and 26% and were not affected by diet. This experiment indicated that excess RDP in the diet of lactating dairy cows could not be efficiently utilized for microbial protein synthesis and was largely lost through urinary N excretion. At a similar MP supply, increased CP or RDP concentration of the diet would result in decreased efficiency of conversion of dietary N into milk protein and less efficient use of ruminal ammonia N for milk protein syntheses.  相似文献   

13.
The effects of ruminal ammonia concentration on bacterial numbers, fermentation pattern and degradation of feed ingredients in the rumen were examined with three nonlactating Holstein cows fitted with ruminal cannulas. Cows were fed twice daily a complete mixed diet (90% whole plant oat silage and 10% concentrate mixture) containing 11.1% CP on a DM basis. Ammonium bicarbonate (NH4HCO3) was infused continuously into the rumen at levels of 0, 95, 190 or 280 g/d. Infusion of NH4HCO3 linearly increased (P less than .05) the concentrations of ruminal ammonia and blood urea N. Total VFA concentrations and mixed bacterial numbers also were increased (P less than .05) by NH4HCO3 infusion. Infusions of NH4HCO3 increased (P less than .05) butyrate and decreased (P less than .05) isobutyrate and isovalerate proportions. Infusion of NH4HCO3 increased (P less than .05) rate of degradation of soybean meal DM but did not (P greater than .05) influence degradation characteristics of fish meal and barley grain. In conclusion, supplementation of N by continuous infusion of NH4HCO3 appeared to stimulate bacterial growth and fermentation but it did not influence extent of ruminal degradation of selected feed ingredients.  相似文献   

14.
In the first of two experiments, four wether lambs (BW = 26.8 kg) and four wether Angora goats (BW = 31.7 kg) were used in two simultaneous 4 x 4 Latin squares to study the influence of condensed tannins (CT) on nutrient usage and concentrations of serum urea N, somatotropin (GH), and insulin (INS) when the animals were fed low-quality diets containing mountain mahogany (MM; Cercocarpus montanus) leaves. Diets were 8% CP and contained 25% or 50% MM (with hay or straw, respectively), either untreated or treated with polyethylene glycol (PEG; molecular weight 3,350) to reduce total reactive CT. Diets treated with PEG and 25% MM diets had less (P less than .05) CT than diets without PEG or those with 50% MM. Diets containing 50% MM resulted in greater N balance and lower serum urea N (P less than .01) than 25% MM diets. Concentrations of GH and INS were similar in animals fed the 25% and 50% MM diets. Reducing CT by adding PEG did not affect N balance or improve nutrient digestion by lambs or goats fed low-quality diets. In Exp. 2, four wether lambs (BW = 28.4 kg) were used in a 4 x 4 Latin square and fed the same diets as animals in Exp. 1 to study the influence of CT on ruminal fermentation and digesta kinetics. Dietary PEG treatment did not affect digesta kinetics except for a 30% increase in ruminal volume; 50% MM diets had faster particulate passage rates (P less than .05) than 25% MM diets. Ruminal ammonia N was greater (P less than .01) in lambs fed PEG-containing or 25% MM diets; however, rate of in situ NDF disappearance was not reduced by the lower ammonia N in the latter diets.  相似文献   

15.
Batch and continuous culture techniques were used to evaluate the effect of the ionophore lysocellin on ruminal fermentation and microbial populations. In batch culture, .5 and 1 ppm (of the fluid) lysocellin markedly decreased (P less than .01) the acetate:propionate ratio without affecting fiber digestion, ammonia concentration, or culture pH. Greater concentrations of lysocellin had negative effects (P less than .05) on fiber digestion and increased (P less than .05) culture pH. In continuous culture, a low level of lysocellin (33 ppm of the diet DM or about .7 ppm of the fluid) decreased pH (P less than .05) and methane (P less than .05) production but had no effect on fiber digestion. Lysocellin tended to increase (P less than .05) OM digestion in corn-based diets but decreased OM digestion in barley-based diets (starch source x lysocellin interaction, P less than .05). In addition, the molar proportion of propionate was increased more in barley- than in corn-based diets. Total anaerobes and amylolytic and lactate-utilizing microorganisms were not affected by the ionophore. In continuous culture, cellulolytic and lactate-producing organisms were insensitive to lysocellin, but, in lysocellin-treated media, cellulolytic organisms were resistant, whereas lactic acid producers were sensitive to lysocellin at 4 ppm. In summary, the ionophore lysocellin alters ruminal fermentation by decreasing ruminal methane production and increasing the molar proportion of propionate; however, effects varied depending on whether corn or barley served as the primary starch source.  相似文献   

16.
Sugar cane is widely used in an in natura forage in tropical countries, but the adoption of silage methods facilitates the preservation of its nutritional value and improves the logistics of its use. To explain differences in performance using alternative forages, it is important to conduct studies that evaluate the various digestion sites for the nutrients provided in diets. However, considering that the collection of omasal digesta is quite laborious and requires the use of a vacuum pump, reticular sampling has been suggested as a promising alternative. Thus, the objective of this study was to evaluate the intake and ruminal digestibility obtained from samples of digesta collected in the reticulum and omasum of cattle fed different diets. Five rumen-fistulated crossbred cattle with an average initial live weight of 336±16.6 kg were used, being distributed in a 5×5 Latin square design. Five diets were evaluated, which contained 60% forage and 40% concentrate on dry matter basis using different forages: maize silage (CS); sugar cane in natura (SCIN); sugar cane silage (SCS0%); sugar cane silage treated with 0.4% calcium oxide (SCS0.4%) or 0.8% calcium oxide (SCS0.8%) on wet basis. The percentage of crude protein (CP) in all of the forages was corrected to 11% based on dry matter (DM) using a mixture of urea/ammonium sulfate (9:1). Six collections of reticular and omasal digesta were obtained over three days at 12 h intervals. To calculate the flow of reticular and omasal nutrients, a double marker system was employed, using cobalt–EDTA and indigestible neutral detergent fiber (NDFi) as markers. The reticular and omasal digesta were similar (P>0.05) to estimate ruminal digestibility of DM, organic matter (OM), CP, neutral detergent fiber (NDF) and non-fiber carbohydrates (NFC). However, the ruminal digestibility of ether extract (EE) and the intestinal digestibility of CP and EE differed (P<0.05) between sampling sites. The results indicate that the omasal digesta is more suitable than the reticular digesta for measuring the ruminal digestion of diet components.  相似文献   

17.
The effects of vitamin E on pH value, total protozoa counts, volatile fatty acid (VFA), ammonia nitrogen and lactate levels were examined using an in vitro ruminal incubation system. The ruminal fluid (100 ml) of the first and second group was supplemented with 0.4 mg or 0.8 mg of vitamin E, respectively. Samples were taken immediately before and following 3, 6, 12 and 24 h of incubation at 39 degrees C and analysed for the total protozoa counts, the pH and the levels of ammonia nitrogen, lactate and VFA. Levels of propionate at 24 h and ammonia nitrogen at 12 and 24 h were significantly higher in the second group than in the control. In contrast, the levels of butyrate at 6, 12 and 24 h and lactate at 6, 12 and 24 h were lower in the second group than in the control. Propionate at 24 h, acetate levels at 6, 12 and 24 hand ammonia nitrogen levels at 6, 12 and 24 h and total rumen protozoa counts at 6, 12 and 24 h were significantly higher in the second group as compared with control. In contrary, butyrate levels at 6, 12 and 24 h, lactate levels at 6, 12 and 24 h were lower in second group than in control. There was no statistically significant difference among the groups in the pH values. In conclusion, the addition of vitamin E to in vitro ruminal fluid was found to increase the concentrations of acetate and propionate, total counts of protozoa, levels of ammonia nitrogen, but to decrease the butyrate and lactate levels of the ruminal aliquots in in vitro ruminal fermentation.  相似文献   

18.
A rumen simulation technique (RUSITEC) apparatus with eight 800 ml fermenters was used to investigate the effects of replacing dietary starch with neutral detergent–soluble fibre (NDSF) by inclusion of sugar beet pulp in diets on ruminal fermentation, microbial synthesis and populations of ruminal cellulolytic bacteria. Experimental diets contained 12.7, 16.4, 20.1 or 23.8% NDSF substituted for starch on a dry matter basis. The experiment was conducted over two independent 15‐day incubation periods with the last 8 days used for data collection. There was a tendency that 16.4% NDSF in the diet increased the apparent disappearance of organic matter (OM) and neutral detergent fibre (NDF). Increasing dietary NDSF level increased carboxymethylcellulase and xylanase activity in the solid fraction and apparent disappearance of acid detergent fibre (ADF) but reduced the 16S rDNA copy numbers of Ruminococcus albus in both liquid and solid fractions and R. flavefaciens in the solid fraction. The apparent disappearance of dietary nitrogen (N) was reduced by 29.6% with increased dietary NDSF. Substituting NDSF for starch appeared to increase the ratios of acetate/propionate and methane/volatile fatty acids (VFA) (mol/mol). Replacing dietary starch with NDSF reduced the daily production of ammonia‐N and increased the growth of the solid‐associated microbial pellets (SAM). Total microbial N flow and efficiency of microbial synthesis (EMS), expressed as g microbial N/kg OM fermented, tended to increase with increased dietary NDSF, but the numerical increase did not continue as dietary NDSF exceeded 20.1% of diet DM. Results suggested that substituting NDSF for starch up to 16.4% of diet DM increased digestion of nutrients (except for N) and microbial synthesis, and further increases (from 16.4% to 23.8%) in dietary NDSF did not repress microbial synthesis but did significantly reduce digestion of dietary N.  相似文献   

19.
本实验旨在探究饲喂高精料日粮对山羊瘤胃和盲肠发酵、生物胺生成与吸收的影响研究。试验选用6头装有永久性瘤胃瘘管的雄性波杂山羊,随机分成低精料组与高精料组,实验期24 d。结果显示,与低精料组相比,饲喂高精料日粮的山羊瘤胃液中总挥发性脂肪酸、乙酸、丙酸、丁酸、戊酸、总支链脂肪酸、酪胺、腐胺、组胺、甲胺和色胺浓度显著性增加(P<0.05),而瘤胃pH和乙丙比显著降低(P<0.05);饲喂高精料日粮的山羊盲肠内容物中的乙酸、丙酸、总挥发性脂肪酸浓度和上述5种生物胺浓度显著增加(P<0.05);同时,瘤胃和盲肠静脉血中的上述5种生物胺的浓度显著提高(P<0.05)。相关性分析结果表明,瘤胃液中酪胺、腐胺、甲胺和色胺浓度与瘤胃静脉血所对应的生物胺浓度呈显著正相关(P<0.05),且盲肠内容物中酪胺、腐胺、甲胺和色胺与盲肠静脉血中对应的生物胺的浓度呈显著正相关(P<0.05)。结果说明,饲喂高精料日粮促进了山羊瘤胃和盲肠发酵,提高了瘤胃与盲肠内容物中生物胺浓度,暗示高精料日粮可能提高消化道上皮的通透性,促进消化道上皮对生物胺的吸收。  相似文献   

20.
Four ruminally and duodenally cannulated crossbred beef steers (397+/-55 kg initial BW) were used in a 4 x 4 Latin square to evaluate the effects of increasing level of field pea supplementation on intake, digestion, microbial efficiency, ruminal fermentation, and in situ disappearance in steers fed moderate-quality (8.0% CP, DM basis) grass hay. Basal diets, offered ad libitum twice daily, consisted of chopped (15.2-cm screen) grass hay. Supplements were 0, 0.81, 1.62, and 2.43 kg (DM basis) per steer daily of rolled field pea (23.4% CP, DM basis) offered in equal proportions twice daily. Steers were adapted to diets on d 1 to 9; on d 10 to 14, DMI were measured. Field pea and grass hay were incubated in situ, beginning on d 10, for 0, 2, 4, 8, 12, 16, 24, 36, 48, 72, and 96 h. Ruminal fluid was collected and pH recorded at -2, 0, 2, 4, 6, 8, 10, and 12 h after feeding on d 13. Duodenal samples were taken for three consecutive days beginning on d 10 in a manner that allowed for a collection to take place every other hour over a 24-h period. Linear, quadratic, and cubic contrasts were used to evaluate the effects of increasing field pea level. Total DMI and OMI increased quadratically (P = 0.09), whereas forage DMI decreased quadratically (P = 0.09) with increasing field pea supplementation. There was a cubic effect (P < 0.001) for ruminal pH. Ruminal (P = 0.02) and apparent total-tract (P = 0.09) NDF disappearance decreased linearly with increasing field pea supplementation. Total ruminal VFA concentrations responded cubically (P = 0.008). Bacterial N flow (P = 0.002) and true ruminal N disappearance (P = 0.003) increased linearly, and apparent total-tract N disappearance increased quadratically (P = 0.09) with increasing field pea supplementation. No treatment effects were observed for ruminal DM fill (P = 0.82), true ruminal OM disappearance (P = 0.38), apparent intestinal OM digestion (P = 0.50), ruminal ADF disappearance (P = 0.17), apparent total-tract ADF disappearance (P = 0.35), or in situ DM disappearance of forage (P = 0.33). Because of effects on forage intake and ruminal pH, field peas seem to act like cereal grain supplements when used as supplements for forage-based diets. Supplementing field peas seems to effectively increase OM and N intakes of moderate-quality grass hay diets.  相似文献   

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