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1.
Eight dual-flow continuous culture fermenters were used in four consecutive periods of 10 d to study the effects of six natural plant extracts on ruminal protein degradation and fermentation profiles. Fermenters were fed a diet with a 52:48 forage:concentrate ratio (DM basis). Treatments were no extract (CTR), 15 mg/kg DM of a mixture of equal proportions of all extracts (MIX), and 7.5 mg/kg DM of extracts of garlic (GAR), cinnamon (CIN), yucca (YUC), anise (ANI), oregano (ORE), or pepper (PEP). During the adaptation period (d 1 through 8), samples for ammonia N and VFA concentrations were taken 2 h after feeding. On d 9 and 10, samples for VFA (2 h after feeding), and peptide, AA, and ammonia N concentrations (0, 2, 4, 6, and 8 h after feeding) were also taken. Differences were declared at P < 0.05. During the adaptation period, total VFA and ammonia N concentrations were not affected by treatments. The acetate proportion was higher from d 2 to 6 in CIN, GAR, ANI, and ORE, and the propionate proportion was lower from d 2 to 4 in CIN and GAR, and from d 2 to 5 in ANI and ORE, compared with CTR. However, the proportion of individual VFA (mol/100 mol) was similar in all treatments after d 6, except for valerate in d 9 and 10, which was lower in PEP (2.8 +/- 0.27) compared with CTR (3.5 +/- 0.27). The average peptide N concentration was 31% higher in MIX, and 26% higher in CIN and YUC compared with CTR (6.5 +/- 1.07 mg/100 mL). The average AA N concentration was 17 and 15% higher in GAR and ANI, respectively, compared with CTR (7.2 +/- 0.77 mg/100 mL). The average ammonia N concentration was 31% higher in ANI and 25.5% lower in GAR compared with CTR (5.5 +/- 0.51 mg/100 mL). The accumulation of AA and ammonia N in ANI suggested that peptidolysis and deamination were stimulated. The accumulation of AA N and the decrease in ammonia N in GAR suggests that deamination was inhibited. The accumulation of peptide N and the numerical decrease in AA N in CIN suggest that peptidolysis was inhibited. Results indicate that plant extracts modified ruminal fermentation, but microbes were adapted to some extracts after 6 d of fermentation. Therefore, data from short-term in vitro fermentation studies may lead to erroneous conclusions, and should be interpreted with caution. Careful selection of these additives may allow the manipulation of protein degradation in the rumen.  相似文献   

2.
Four Holstein heifers (360 +/- 22 and 450 +/- 28 kg of BW in Exp. 1 and 2, respectively) fitted with ruminal trocars were used in 4 x 4 Latin square designs to evaluate the effects on ruminal microbial fermentation of the following: Exp. 1, no additive, alfalfa extract (30 g/d, AEX), a mixture of cinnamaldehyde (0.18 g/d) and eugenol (0.09 g/d; CIE1), and AEX and CIE1 in combination; and Exp. 2, no additive, anise oil (2 g/d), capsicum oil (1 g/d), and a mixture of cinnamaldehyde (0.6 g/d) and eugenol (0.3 g/d). Heifers were fed a 90:10 concentrate:barley straw diet (16% CP; 25% NDF) for ad libitum intake. Each period consisted of 15 d for adaptation and 6 d for sampling. On d 16 to 18, DM and water intakes were measured. On d 19 to 21 ruminal contents were sampled at 0, 3, 6, 9, and 12 h after feeding to determine ruminal pH and the concentrations of VFA, L-lactate, large peptides, small peptides plus AA (SPep+AA), and ammonia N. On d 20 and 21, samples of ruminal fluid were collected at 0 and 3 h after feeding to determine protozoal counts. In Exp. 1, CIE1 and AEX decreased (P < 0.05) total DMI, concentrate DMI, and water intake. The increase (P < 0.05) in SPep+AA and the decrease (P < 0.05) in ammonia N when supplementing CIE1 suggest that deamination was inhibited. Treatment AEX increased (P < 0.05) the acetate to propionate ratio, which is less efficient for beef production. Treatment CIE1 increased (P < 0.05) counts of holotrichs. Effects of AEX and CIE1 were not additive for many of the measured metabolites. In Exp. 2, treatments had no effect on ruminal pH, total VFA concentration, and butyrate proportion. The capsicum oil treatment increased (P < 0.05) DMI, water intake, and SPep+AA N concentration and decreased (P < 0.05) acetate proportion, branched-chain VFA concentration, and large peptide N concentration. The cinnamaldehyde (0.6 g/d) and eugenol (0.3 g/d) treatment decreased (P < 0.05) water intake, acetate proportion, branched-chain VFA, L-lactate, and ammonia N concentrations and increased (P < 0.05) propionate proportion and SPep+AA N concentration. The anise oil treatment decreased (P < 0.05) acetate to propionate ratio, branched-chain VFA and ammonia N concentrations, and protozoal counts. The results indicate that at the doses used a mixture of cinnamaldehyde and eugenol, anise oil, and capsicum oil may be useful as modifiers of rumen fermentation in beef production systems.  相似文献   

3.
One in vitro and one in vivo metabolism experiment were conducted to examine the effects of supplemental Zn on ruminal parameters, digestion, and DMI by heifers fed low-quality prairie hay supplemented with urea. In Exp. 1, prairie hay was incubated in vitro for 24 h with five different concentrations of supplemental Zn (0, 5, 10, 15, and 20 ppm) and two concentrations of supplemental Mn (0 and 100 ppm), both provided as chloride salts. Added Mn increased (P < 0.02) IVDMD, but added Zn linearly decreased (P < 0.03) IVDMD. Added Zn tended to increase the amount of residual urea linearly (P < 0.06) at 120 min and quadratically (P < 0.02) at 180 min of incubation, although added Mn counteracted these effects of added Zn. Six 363-kg heifers in two simultaneous 3 x 3 Latin squares were fed prairie hay and dosed once daily via ruminal cannulas with urea (45 or 90 g/d) and with Zn chloride to provide the equivalent of an additional 30 (the dietary requirement), 250, or 470 ppm of dietary Zn. After a 7-d adaptation period, ruminal contents were sampled 2, 4, 6, 12, 18, 21, and 24 h after the supplement was dosed. Supplemental Zn did not alter prairie hay DMI (mean = 4.9 kg/d) or digestibility, although 470 ppm added Zn tended to decrease (P < 0.06) intake of digestible DM, primarily due to a trend for reduced digestibility with 470 ppm supplemental Zn. Zinc x time interactions were detected for both pH (P = 0.06) and NH3 (P = 0.06). At 2 h after dosing, ruminal pH and ruminal ammonia were linearly decreased (P < 0.05; P < 0.01) by added Zn. At 5 h after feeding, ruminal pH was linearly increased (P < 0.05) by added Zn, suggesting that added Zn delayed ammonia release from urea. The molar proportion of propionate in ruminal fluid was linearly and quadratically increased (P < 0.02; P < 0.01) whereas the acetate:propionate ratio was linearly and quadratically decreased (P = 0.02; P < 0.05) by added Zn. Through retarding ammonia release from urea and increasing the proportion of propionate in ruminal VFA, Zn supplementation at a concentration of 250 ppm may decrease the likelihood of urea toxicity and increase energetic efficiency of ruminal fermentation.  相似文献   

4.
不同精料补饲水平对藏绵羊瘤胃内环境参数的影响   总被引：2，自引：0，他引：2  
选择1.2岁左右藏绵羊30只,随机分3组,采用单因子分组设计,以青干草为基础日粮,按每只150,300,450 g/d 3种精料水平补饲,研究不同精料补饲水平对藏绵羊瘤胃代谢参数变化规律的影响。结果表明;随精料补饲水平提高,藏绵羊瘤胃液pH值下降,NH3-N浓度、NH3-N浓度平均值、总挥发性脂肪酸(VFA)浓度显著增加(P<0.05)。在本试验条件下,从藏绵羊瘤胃内环境的稳定方面考虑,藏绵羊每日补饲精料300 g效果最佳。  相似文献   

5.
Crossbred beef steers (n = 615) were used in a 152-d experiment to compare steam-flaked corn (SFC) diets containing 0, 30, or 60% wet corn gluten feed (WCGF). On d 114 to 118, ruminal and fecal samples were collected from 180 steers and analyzed for pH, VFA, and total and acid-resistant Escherichia coli and coliforms. Acid resistance of E. coli and coliform populations was determined by exposure of the samples for 1 h in pH 2, 4, and 7 citric acid/sodium phosphate buffers. Increasing levels of WCGF linearly decreased total ruminal VFA (P = 0.01) and total fecal VFA (P = 0.06), but linearly increased ruminal and fecal acetate:propionate (P < 0.01) ratio and ruminal and fecal pH (P < 0.05). Feeding increasing WCGF levels resulted in a quadratic response (P < 0.05) with respect to numbers of ruminal E. coli and total coliform populations resistant to pH 4 exposure. Steers fed 30% WCGF had higher (0.7 log units) ruminal E. coli and total coliforms after exposure at pH 4 compared to steers fed 0 or 60% WCGF. Populations of E. coli and total coliforms at pH 2 and 7 were similar for all dietary treatments. Dietary WCGF linearly increased DMI (P = 0.07) and liver abscesses (P = 0.03) and linearly decreased dietary NEg (P = 0.02). Average daily gain and feed efficiencies were greatest when steers were offered 30% WCGF (quadratic, P < 0.05). Dietary manipulations that reduce acid concentrations may not correspond to changes in acid resistance of E. coli and total coliform populations detected in the gastrointestinal tracts of cattle. Moderate levels of WCGF complement SFC finishing diets.  相似文献   

6.
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   

7.
Twelve ruminally cannulated crossbred Angus steers were used to evaluate ruminal fermentation characteristics and diet digestibility when 30% (DM) corn dried distillers grains with solubles (DDGS) containing 0.42 or 0.65% (DM) of dietary S was incorporated into finishing diets based on steam-flaked corn (SFC) or dry-rolled corn (DRC). The study was a replicated, balanced randomized incomplete block design with a 2 × 2 factorial arrangement of treatments. Factors consisted of dietary S concentration (0.42 and 0.65% of DM; 0.42S and 0.65S, respectively) and grain processing method (SFC or DRC). The 0.65S concentration was achieved by adding H(2)SO(4) to DDGS before mixing rations. Steers were assigned randomly to diets and individual, slatted-floor pens, and fed once daily for ad libitum intake. Two 15-d experimental periods were used, each consisting of a 12-d diet adaptation phase and a 3-d sample collection phase. Samples were collected at 2-h intervals postfeeding during the collection phase. Ruminal pH was measured immediately after sampling, and concentrations of ruminal ammonia and VFA were determined. Fecal samples were composited by steer within period and used to determine apparent total tract digestibilities of DM, OM, NDF, CP, starch, and ether extract. Feeding 0.65S tended (P = 0.08) to decrease DMI but resulted in greater apparent total tract digestibilities of DM (P = 0.04) and ether extract (P = 0.03). Ruminal pH increased (P < 0.05) in steers fed 0.65S diets, which may be attributable, in part, to decreased (P = 0.05) VFA concentrations and greater (P < 0.01) ruminal ammonia concentrations when 0.65S was fed, compared with feeding 0.42S. These effects were more exaggerated in steers fed DRC (interaction, P < 0.01), compared with steers fed SFC. Steers fed DRC-0.65S had greater (P < 0.01) acetate concentration than steers fed DRC-0.42S, but acetate concentration was not affected by S concentration when SFC was fed. Propionate concentration was decreased (P < 0.01) in steers fed SFC-0.65S compared with steers fed SFC-0.42S, but dietary S concentration had no effect on propionate concentration when DRC was fed. Butyrate concentration was less (P < 0.01) in steers fed 0.65S diets than in steers fed 0.42S. Lactate concentrations tended (P = 0.06) to decrease in steers fed 0.65S diets. Feeding DDGS with increased S concentration may decrease feed intake and ruminal VFA concentration but increase ruminal ammonia concentration.  相似文献   

8.
The objective of this study was to examine the effects of cinnamaldehyde (CDH), garlic (GAR) and juniper berry (JUN) essential oils (200 mg/kg of DM) on performance and carcass characteristics of lambs fed a barley-based concentrate diet ad libitum. For this purpose, 40 ewes' lambs (23.5 ± 1.11 kg initial live weight, LW) were used in a random block design over a 13-week period. Feeding CDH, GAR or JUN did not affect dry matter intake (DMI) but the average daily gain (ADG) of lambs supplemented with CDH and JUN was higher (P = 0.002) as compared to lambs fed GAR or the control diet. Feed conversion (DMI/ADG) was numerically improved when lambs were fed CDH (4.8) and JUN (4.7) compared to those fed GAR (5.2) or the control diet (5.3). There were no effects of feed additives on ruminal pH and concentrations of ammonia and total VFA. Serum concentrations of glycerol and total glycerides were lower and higher (P ≤ 0.03) in lambs fed CDH or JUN respectively, as compared to lambs fed GAR or the control diet. Hot dressed carcass weight was similar among treatments (23.7 ± 0.75 kg; P = 0.18) whereas saleable meat tended (P = 0.13) to increase (+ 9%) in lambs fed CDH and JUN compared to those fed GAR or the control diet. Feeding CDH, GAR or JUN had little effect on the overall fatty acid composition of back fat and liver and only minor effects on meat flavour characteristics.  相似文献   

9.
本试验旨在研究高谷物日粮对山羊瘤胃上皮形态结构及单羧酸转运蛋白(monocarboxylate transporter, MCT)和钠钾ATP酶mRNA表达的影响。将10头装有永久性瘤胃瘘管的健康阉割公山羊随机分为饲喂全粗料日粮的对照组(Hay,0%谷物,n=5)和饲喂高谷物日粮的处理组(HG,65%谷物,n=5),试验期为7周。试验开始后,于每周晨饲后的0、2、3、4、6、8和12 h连续采集瘤胃液监测瘤胃pH值的变化,收集其中第0、3、6和12 h的瘤胃液待测挥发性脂肪酸(volatile fatty acid, VFA)浓度。试验的第50天,屠宰采集瘤胃上皮用于形态学及基因定量分析。研究结果显示:与全粗料组山羊相比,高谷物组山羊瘤胃pH值、乙酸浓度及乙丙比都显著下降(P<0.001),而瘤胃丙酸浓度、丁酸浓度及其他VFA浓度都显著升高(P<0.001);高谷物日粮组的瘤胃乳头长度显著高于对照组(P=0.001),瘤胃乳头宽度显著低于对照组(P<0.001),但是两组间的瘤胃乳头表面积并无显著差异;透射电镜结果显示,长期饲喂高谷物日粮导致瘤胃上皮细胞线粒体发生降解;实时定量PCR结果表明,与对照组相比,高谷物日粮显著升高了MCT1(P<0.001)和钠钾ATP酶(P=0.001)的mRNA表达量,显著降低了MCT4的mRNA表达量(P=0.041),但对MCT2的表达没有显著影响(P=0.305);进一步分析这些基因的mRNA表达量与pH值和VFA浓度之间的相关性,结果显示,MCT1和钠钾ATP酶的mRNA表达量与瘤胃pH值和乙酸浓度呈显著负相关,与总VFA、丙酸、丁酸的含量呈显著正相关,而MCT4的mRNA表达量与pH值呈显著正相关,与总VFA、丙酸、丁酸的含量呈显著负相关。以上结果提示:高精料引起的瘤胃pH值下降和VFA的变化可能与瘤胃上皮MCT和钠钾ATP酶表达量的变化相关。研究结果对深入认识高谷物饲喂引发的瘤胃功能紊乱具有重要意义。  相似文献   

10.
Six adult African-type hair sheep (BW = 40.3 +/- 6.3 kg) fitted with ruminal and duodenal cannulas were subjected to four treatments. Sheep were offered basal diets at a rate of 80 g of DM/kg of metabolic BW (equivalent to ad libitum access) consisting either of a low-quality grass hay (Brachiaria dictyoneura, 3.7% CP, DM basis) alone or in combination with a forage legume (Cratylia argentea, 18.6% CP, DM basis) in a 3:1 ratio (DM basis). In addition, 0 or 8 g of DM of Sapindus saponaria fruits (12.0% crude saponins, DM basis) per kilogram of metabolic BW was administered intraruminally. Supplementation of C. argentea increased intakes of OM (+21%; P < 0.01) and CP (+130%; P < 0.001), as well as ruminal fluid ammonia N concentrations (from 2.40 to 8.43 mg/dL; P < 0.001). Apparent OM and N digestibilities were not affected by legume addition, but ADF digestibility decreased by 10% (P < 0.01). Total ruminal VFA concentration was unchanged, but acetate:propionate was lower (P < 0.01) and isobutyrate proportion was greater (P < 0.001) with the legume addition. Legume supplementation increased duodenal flows of total N (+56%; P < 0.001), nonammonia N (+52%; P < 0.001), ruminal escape N (+80%; P < 0.001), and microbial N (+28%; P < 0.05). Microbial efficiency was not affected by legume addition. Supplementation of S. saponaria increased (P < 0.05) dietary OM intake by 14%, but had no effect on CP intake and ruminal fluid ammonia concentration or on OM and N digestion. Digestibility of ADF was decreased (P < 0.01) by 10% with S. saponaria as was acetate:propionate (P < 0.001) and the isobutyrate proportion (P < 0.001). Ruminal protozoa counts increased (P < 0.01) by 67% with S. saponaria. Duodenal N flows were not significantly affected by S. saponaria supplementation, except for microbial N flow (+34%; P < 0.01). Microbial efficiency was greater (P < 0.05) by 63% with the addition of S. saponaria. Few interactions between legume and S. saponaria supplementation were observed. The NDF digestibility was decreased with S. saponaria in the grass-alone diet, but not in the legume-supplemented diet (interaction; P < 0.05). Interactions were absent in ruminal fermentation measures and duodenal N flow, indicating that effects were additive. Results suggest that, even when not decreasing ruminal protozoa count, supplementation of S. saponaria fruits is a beneficial way to improve ruminal VFA profile, microbial efficiency, and duodenal flow of microbial protein in sheep fed tropical grass-alone or grass-legume diets.  相似文献   

11.
不同厚度蒸汽压片处理对玉米活体外瘤胃发酵的影响   总被引：2，自引：2，他引：0  
试验以未处理的玉米及两种不同厚度蒸汽压片玉米(压片厚度为1.5mm,SFC 1.5;压片厚度为2.0mm,SFC 2.0)为材料,采用营养成分分析、活体外人工瘤胃产气量试验,研究不同厚度蒸汽压片处理对玉米营养成分、淀粉糊化度和活体外发酵特性的影响。结果表明,不同厚度蒸汽压片处理显著降低玉米粗蛋白质和粗脂肪含量(P0.05),显著提高了玉米的淀粉糊化度(P0.05);并且显著提高了玉米在瘤胃液内的淀粉降解率和体外产气速度(P0.05),显著降低了瘤胃液中氨态氮(NH3-N)浓度(P0.05);降低压片厚度(1.5和2.0mm),蒸汽压片玉米淀粉糊化度增加约17%(88.76%和71.60%),SFC 1.5的体外产气速度、4h干物质和淀粉产气率显著高于SFC 2.0(P0.05)。不同厚度蒸汽压片处理对玉米瘤胃48h产气量、12和24h瘤胃液pH、总挥发性脂肪酸产量及乙酸、丙酸、乙酸/丙酸、异丁酸、异戊酸、戊酸摩尔比影响均不显著(P0.05)。综上所述,不同厚度蒸汽压片处理可显著提高玉米在瘤胃内淀粉降解率和降解速度,降低瘤胃液中氨态氮浓度,而对48h产气量及其他发酵参数没有明显影响。  相似文献   

12.
The effects of season of growth and monensin treatment on ruminal digestion of fresh-cut autumn and spring pasture were measured in a single group of ruminally fistulated castrated male sheep, housed indoors in metabolism crates. Responses were assessed in terms of ruminal volatile fatty acid molar proportions, ammonia concentration, pH, apparent digestibility of the pasture, and nitrogen balance of the animals. Blood plasma concentrations of insulin, glucose, beta-hydroxybutyrate, urea, and NEFA were also evaluated. Autumn pasture contained significantly lower proportions of water-soluble carbohydrate (P < 0.05), cellulose (P < 0.05), and lignin (P < 0.05) and increased pectin (P < 0.05), hemicellulose (P < 0.05), and crude protein (P < 0.10) concentrations when compared with spring pasture. Voluntary DMI by sheep of autumn pasture was lower (P < 0.01) than that of spring pasture and was significantly (P < 0.05) reduced by monensin treatment. Monensin treatment significantly decreased the ruminal molar proportions of acetic acid (P < 0.10) and butyric acid (P < 0.001) and increased the molar proportions of propionic acid (P < 0.001) and minor VFA (P < 0.01). Nitrogen retention of the sheep was significantly (P < 0.05) reduced by monensin treatment. Plasma glucose levels were increased (P < 0.10) by monensin treatment during the fourth 5-d collection period in both seasons. Chemical analysis suggested that the composition of autumn pasture was different from that of spring pasture and that this was manifested in vivo by increased DMI and digestibility of spring vs autumn pasture. Ruminal fermentation of autumn pasture also had an increased acetate-to-propionate ratio compared with spring pasture. Monensin treatment acted consistently across seasons by increasing the proportion of propionate and decreasing the proportion of acetate in ruminal fluid.  相似文献   

13.
Four beef Holstein heifers (BW = 438 ± 71 kg) fitted with a 1-cm i.d. plastic ruminal trocars were used in a 4 × 4 Latin square design to evaluate the effect of 3 doses of capsicum extract (CAP) on intake, water consumption, and ruminal fermentation in heifers fed a high-concentrate diet. Animals were fed (DM basis) 10% barley straw and 90% concentrate (32.2% barley grain, 27.9% ground corn, 7.5% wheat bran, 10.7% soybean meal, 10.7% soybean hulls, 7.2% corn gluten feed, 3.1% mineral-vitamin mix; 16.6% CP, 18.3% NDF). Treatments were no additive (CTR), 125 (CAP125), 250 (CAP250), and 500 (CAP500) mg/d of capsicum oleoresin standardized with 6% of capsaicin and dihydrocapsaicin (XTract 6933, Pancosma, Geneva, Switzerland). Each experimental period consisted of 25 d (15 d for adaptation, 5 d of continuous measurement of DMI, and 3 d for rumen sample collection). Animals had ad libitum access to water and feed offered once daily at 0800 h. Data were analyzed by the MIXED procedure of SAS. The model included the fixed effects of period and treatment, the random effect of heifer, and the residual error. The effects were tested for linear and quadratic effects. A linear response was observed (CTR, CAP125, CAP250, and CAP500, respectively) for DMI (8.56, 9.84, 8.68, and 9.40 kg/d; P < 0.04), ruminal pH (6.03, 5.84, 5.96, and 5.86; P < 0.08) and total VFA (134.3, 144.8, 140.1, and 142.8 mM; P < 0.08). There was a strong correlation between water consumption and DMI (R(2) = 0.98). Dry matter intake in the first 2 h after feeding was reduced (P < 0.05) in all CAP treatments compared with control. The molar proportion of acetate tended to decrease linearly (from 59.6 to 55.5 mol/100 mol; P < 0.06), and ammonia N concentration tended to increase linearly (from 14.4 to 16.0 mg N/dL; P < 0.08). In contrast, the molar proportion of propionate (23.8 mol/100 mol), butyrate (14.2 mol/100 mol), and lactate (0.28 mol/100 mol) were not affected by treatments. Results indicate that capsicum extract stimulated DMI and modified the pattern of DMI in beef cattle fed high concentrate diets.  相似文献   

14.
Three sheep, each fitted with a ruminal cannula and duodenal re-entrant cannulae were given three isonitrogenous, isoenergetic diets in a Latin Square design. Each diet contained approximately 60% DM as barley grain and 40% of total N as either white fish meal, soya-bean meal or urea. These diets were fed continuously and supplied about 28 g N/day. Diets containing such large amounts of barley grain usually produce wide variations in the rumen volatile fatty acid (VFA) proportions and these have been correlated with various other digestive characteristics. Several ruminal and duodenal components were measured in this study and interrelationships between them sought. The molar proportions of VFA varied widely from 45-67% for acetate, 13-48% for propionate and 7-23% for butyrate. Rumen pH was positively correlated with acetate (P less than 0.01), but negatively so with propionate (P less than 0.01) and butyrate (P less than 0.1). The numbers of rumen ciliate protozoa also varied widely and were related to rumen pH (P less than 0.05) and VFA proportions; positively to acetate (P less than 0.001) and butyrate (P less than 0.01) but negatively to propionate (P less than 0.001). Duodenal N was always less than fed N. The mean composition of this duodenal N was 10.1% ammonia-N, 6.7% RNA-N, 79.0% amino acid-N and 7.3% was unaccounted for. Efficiencies of synthesis of microbial and bacterial crude protein (derived from 35S and 2,6-diaminopimelic acid data) ranged from 10.5 to 42.2 g microbial N per kg apparently digested organic matter (ADOM) and 5.0 to 27.9 g bacterial N per kg ADOM. Division of VFA patterns into either propionate or butyrate type fermentations suggested several further interrelationships. No relationship was established between these fermentation patterns and the extent or efficiency of microbial crude protein synthesis. Possible interrelationships between different digestive characteristics are discussed and a plea made for both more extensive and intensive experimentation before such designation of cause and effect can be assigned.  相似文献   

15.
酵母菌培养物对瘤胃发酵的影响   总被引：3，自引：0，他引：3  
本研究采用完全随机试验设计,使用持续动态人工瘤胃装置,研究了酿酒酵母菌培养物对瘤胃发酵的影响。试验处理为对照组、1%和5%(占发酵液体积)酿酒酵母菌培养物添加组。通过对瘤胃液pH、微生物蛋白质(MCP)、氨态氮(NH3-N)、挥发性脂肪酸(VFA)浓度的测定得出以下结果:添加酿酒酵母菌培养物对pH和NH3-N浓度没有显著影响(P>0.05);5%酿酒酵母菌培养物添加组显著提高MCP浓度并降低了丙酸浓度(P<0.05);而酿酒酵母菌培养物对总挥发酸酸、乙酸、丁酸和乙、丙酸比例没有显著影响(P>0.05)。以上结果表明:添加一定量的酿酒酵母菌培养物可在不改变瘤胃发酵类型的情况下,促进微生物蛋白质的合成。  相似文献   

16.
Three sheep fitted with a ruminal cannula and an abomasal catheter were used to study water kinetics and absorption of VFA infused continuously into the rumen. The effects of changing VFA concentrations in the rumen by shifting VFA infusion rates were investigated in an experiment with a 3 x 3 Latin square design. On experimental days, the animals received the basal infusion rate of VFA (271 mmol/h) during the first 2 h. Each animal then received VFA at a different rate (135, 394, or 511 mmol/h) for the next 7.5 h. Using soluble markers (polyethylene glycol and Cr-EDTA), ruminal volume, liquid outflow, apparent water absorption, and VFA absorption rates were estimated. There were no significant effects of VFA infusion rate on ruminal volume and water kinetics. As the VFA infusion rate was increased, VFA concentration and osmolality in the rumen were increased and pH was decreased. There was a biphasic response of liquid outflow to changes in the total VFA concentration in the rumen, as both variables increased together up to a total VFA concentration of 80.1 mM, whereas, beyond that concentration, liquid outflow remained stable at an average rate of 407 mL/h. There were significant linear (P = 0.003) and quadratic (P = 0.001) effects of VFA infusion rate on the VFA absorption rate, confirming that VFA absorption in the rumen is mainly a concentration-dependent process. The proportion of total VFA supplied that was absorbed in the rumen was 0.845 (0.822, 0.877, and 0.910 for acetate, propionate, and butyrate, respectively). The molar proportions of acetate, propionate, and butyrate absorbed were affected by the level of VFA infusion in the rumen, indicating that this level affected to a different extent the absorption of the different acids.  相似文献   

17.
The objective of this study was to examine the effects of Aspergillus oryzae fermentation extract (Amaferm) on the in vitro ruminal fermentation of coastal bermudagrass, soluble starch and amino acids. Mixed ruminal microorganisms were incubated in anaerobic media for either 24 h (Amaferm alone, soluble starch, amino acids) or 48 h (bermudagrass). Amaferm was added to the incubation bottles (n = 4) at concentrations of 0, .4 or 1.0 g/liter. When mixed ruminal microorganisms were incubated with only Amaferm, the 1.0 g/liter concentration increased the production of hydrogen (H2; P less than .001), methane (CH4; P less than .01), acetate (P less than .05), butyrate (P less than .01), total VFA (P less than .05) and NH3 (P less than .05). Addition of both levels of Amaferm to soluble-starch fermentations tended to enhance the production of H2 (P less than .11), CH4 (P less than .15), acetate (P less than .29) and total VFA (P less than .19); propionate production was increased (P less than .10) by 1.0 g/liter Amaferm, resulting in a decrease (P less than .05) in the acetate:propionate ratio. Fermentation of amino acids plus 1.0 g/liter Amaferm enhanced the production of acetate (P less than .05), propionate (P less than .05), valerate (P less than .01) and total VFA (P less than .10) and decreased the acetate:propionate ratio (P less than .05). In addition, NH3 production tended (P less than .19) to increase with both levels of Amaferm. When bermudagrass was the substrate, few changes in fermentation products were observed with Amaferm treatment.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
Four steers fitted with a ruminal cannula and chronic indwelling catheters in the mesenteric artery, mesenteric vein, hepatic portal vein, hepatic vein, and the right ruminal vein were used to study the absorption and metabolism of VFA from bicarbonate buffers incubated in the temporarily emptied and washed reticulorumen. Portal and hepatic vein blood flows were determined by infusion of p-aminohippurate into the mesenteric vein, and portal VFA fluxes were calibrated by infusion of isovalerate into the ruminal vein. The steers were subjected to four experimental treatments in a Latin square design with four periods within 1 d. The treatments were Control (bicarbonate buffer) and VFA buffers containing 4, 12, or 36 mmol butyrate/kg of buffer, respectively. The acetate content of the buffers was decreased with increasing butyrate to balance the acidity. The butyrate absorption from the rumen was 39, 111, and 300 +/- 4 mmol/h for the three VFA buffers, respectively. The ruminal absorption rates of propionate (260 +/- 12 mmol/h), isobutyrate (11.4 +/- 0.7 mmol/h), and valerate (17.3 +/- 0.7 mmol/h) were not affected by VFA buffers. The portal recovery of butyrate and valerate absorbed from the rumen increased (P < 0.01) with increasing butyrate absorption and reached 52 to 54 +/- 4% with the greatest butyrate absorption. The liver responded to the increased butyrate absorption with a decreasing fractional extraction of propionate and butyrate, and with the greatest butyrate absorption, the splanchnic flux was 22 +/- 1% and 18 +/- 1% of the absorbed propionate and butyrate, respectively. The increased propionate and butyrate release to peripheral tissues was followed by increased (P < 0.05) arterial concentrations of propionate (0.08 +/- 0.01 mmol/kg) and butyrate (0.07 +/- 0.01 mmol/kg). Arterial insulin concentration increased (P = 0.01) with incubation of VFA buffers compared with Control and was numerically greatest with the greatest level of butyrate absorption. We conclude that the capacity to metabolize butyrate by the ruminal epithelium and liver is limited. If butyrate absorption exceeds the metabolic capacity, it affects rumen epithelial and hepatic nutrient metabolism and affects the nutrient supply of peripheral tissues.  相似文献   

19.
Response to monensin in cattle during subacute acidosis   总被引：1，自引：0，他引：1  
A steer metabolism study was conducted to measure changes in ruminal and blood components in response to monensin level following an abrupt switch from forage to a concentrate diet. Six ruminal-cannulated crossbred steers (373 kg) were fed either 0, 150 or 300 mg monensin per head daily in a replicated 3 X 3 Latin-square design. In all treatments, ruminal pH declined to a low of 5.4 to 5.6 12 h post-feeding, suggesting steers experienced subacute acidosis. Also in the first 12 h post-feeding, all treatments exhibited nearly a twofold increase in total ruminal volatile fatty acid (VFA) concentrations, while peak ruminal lactate concentrations ranged from .86 to 1.50 mM. During the entire 48-h period, there were no significant treatment differences in blood pH, HCO3- or ruminal lactate, although there was a trend of higher ruminal and blood lactate associated with increased level of monensin supplementation. Feeding higher levels of monensin resulted in higher pH and propionate with lower acetate and butyrate concentrations. Increasing the level of monensin fed resulted in reduced (P less than .01) total ruminal VFA concentrations. Ruminal pH was more highly correlated to total ruminal VFA concentrations (r = -.69, P less than .01) than lactate concentrations (r = -.14, P less than .10). Results from this study indicate the significance of total ruminal organic acid concentration rather than ruminal lactate concentration during subacute acidosis. Monensin maintained a higher ruminal pH by reducing concentrations of VFA.  相似文献   

20.
Six ruminally cannulated steers (345 +/- 20 kg initial BW) were used in a 6 x 6 Latin square to evaluate effects of diet and antibiotics on ruminal protein metabolism. Two diets and three antibiotic treatments were arranged factorially. One diet contained (DM basis) 72% dry-rolled corn, 12% soybean meal, 10% alfalfa hay, and 4% molasses (SBM), and the other contained 63% dry-rolled corn, 30% wet corn gluten feed, and 5% alfalfa hay (WCGF). Antibiotic treatments included control, virginiamycin (175 mg/d; VM), and monensin/tylosin (250 and 100 mg/d, respectively; MT). Steers were fed at 12-h intervals at a rate of 2.4% of empty BW daily. Each period included 18 d of adaptation and 3 d of ruminal fluid collections. Samples were collected at 0, 2, 4, 6, 8, and 10 h after the morning feeding on d 19 and 20. On d 21, rumens were dosed 2 h after the morning feeding with 350 g of solubilized casein to evaluate in vivo ruminal protease and deaminase activities. Ruminal fluid samples were collected 1, 2, 3, 4, and 6 h after the casein dose. On d 19 and 20, antibiotics had no effect on ruminal pH or concentrations of VFA, lactate, ammonia, ciliated protozoa, alpha-amino nitrogen (AAN), or peptide N, but VM reduced (P < 0.01) the concentration of isovalerate compared to MT and control. After casein dosing (d 21), peptide N concentration was unaffected by antibiotics, but AAN were higher (P < 0.01) for VM than MT and control. Relative to MT and control, VM reduced ruminal isovalerate (P = 0.05) and increased ruminal propionate (P < 0.01) on d 21. Ruminal pH was lower (P < 0.01) in steers fed SBM than in steers fed WCGF, but lactate concentrations were unaffected by diet. Steers fed SBM had higher (P < 0.05) ruminal concentrations of total VFA and propionate. Ammonia concentrations were lower before feeding and higher after feeding for steers fed WCGF (P < 0.01). Steers fed WCGF had higher counts of total ciliated protozoa than steers fed SBM (P < 0.05) due to greater Entodinium sp. (P < 0.05). Steers fed WCGF had higher (P < 0.01) ruminal AAN and peptide N concentrations than those fed SBM on d 19 and 20. After casein dosing, ruminal peptide N concentrations were similar, but AAN were lower (P < 0.01) for WCGF than SBM. Overall, VM appeared to depress ruminal deaminase activity, and MT had minimal effects on ruminal fermentation products. The protein in WCGF appeared to be more readily degradable than that in SBM.  相似文献   

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