Effect of different volatile fatty acids mixtures on energy metabolism in cattle

Four Friesian steers (mean BW = 282 kg) were given mixtures of VFA and casein by intragastric infusion to give a total energy input of 675 kJ/kg BW.75. Casein supplied 16.3% of the energy and 777 mg N/kg BW.75. The molar proportion of butyric acid was held constant at 8 mol/100 mol, and the acetic and propionic acids varied inversely. Acetic acid was varied in 12 increments from 11 to 91 mol/100 mol and propionic acid proportion varied inversely. Heat production, blood (urea, insulin, beta-hydroxybutyrate, free fatty acids) and urine metabolites (urea, N, VFA) were measured. There were no differences (P greater than .05) in heat production until the acetic acid proportions exceeded approximately 90 mol/100 mol, at which point there was a decrease in heat production (P less than .05) accompanied by a considerable excretion of acetic acid in the urine. Above 80 mol/100 mol acetic acid, beta-hydroxybutyrate was greatly elevated, accompanied by a small decrease in blood glucose and blood insulin together with an increase in blood free fatty acid concentration. There was also an elevation of N excretion in the urine. When the proportion of propionic acid exceeded 76 mol/100 mol there were some metabolic disturbances resulting in blood hemolysis, an increase in N excretion in the urine, and nervous disposition of the animals. It is concluded that differences in heat production between roughage and concentrate diets are not likely to be a result of differences in the energetic response to different proportions of VFA. Differences in activity during standing, feeding, and ruminating may, therefore, be more important.(ABSTRACT TRUNCATED AT 250 WORDS)     

西藏地区不同牧草体外发酵特性研究

本文旨在利用体外产气法评定西藏地区不同牧草营养价值。选取西藏地区5种常见牧草,通过单因素试验设计,利用体外产气法评定5种牧草体外发酵48 h累积产气量、理论最大产气量(V_f)、初始产气速率(FRD_0)、达到最大产气量一半时所需时间(t_(0.5))、体外干物质消失率(IVDMD)、体外中性洗涤纤维消失率(IVNDFD)、p H、氨态氮(NH_3-N)浓度以及挥发性脂肪酸(VFA)产量。结果表明,体外发酵48 h后,苇状羊茅体外48 h累积产气量、V_f、FRD_0、IVDMD及甲烷(CH_4)、乙酸、丙酸、丁酸和总VFA产量均显著高于其他4种牧草(P0.05),但其体外发酵p H及乙酸/丙酸显著低于其他4种牧草(P0.05);紫花苜蓿体外NH_3-N浓度最高,显著高于其他4种牧草(P0.05)。综上分析,苇状羊茅体外发酵效果最佳,与其他试验牧草相比,更容易被瘤胃微生物降解利用。     

Effect of fats and fatty acid combinations on ruminal fermentation in semi-continuous in vitro cultures

Four in vitro trials were conducted to determine how ruminal fermentation is affected by source of fat, level of fat, and combinations of fatty acids. Trials I and II examined how volatile fatty acids (VFA) were changed by three sources of fat (blended animal-vegetable fat, corn oil and tallow fatty acids) each added to a hay substrate at six levels (0, 2, 4, 6, 8 and 10%). Increasing blended fat caused no changes in VFA levels except to decrease butyric acid from 12.1 to 9.9% of the total VFA (P less than .05). Corn oil and tallow fatty acids both increased propionic acid, causing the ratio of acetic to propionic acids (A/P) to decrease (P less than .01). Trial III tested different ratios of oleic/stearic and linoleic/stearic acids to determine if certain combinations were better for fermentation. There was no evidence of synergism among fatty acids since increasing the ratio of unsaturates steadily reduced A/P. Trial IV was designed to determine how changes in VFA levels reflect changes in fiber digestibility of substrates containing added fat. Volatile fatty acids having significant regressions with fiber digestibility were acetic acid (r = .648), propionic acid (r = -.670), total VFA concentration (r = .742) and A/P (r = .831). Results are interpreted to show that blended animal-vegetable fats are less toxic in the rumen than equal levels of other lipids, and the beneficial effects of blended fat cannot be attributed to a unique combination of fatty acids acting synergistically.     

Laidlomycin butyrate--an ionophore with enhanced intraruminal activity

The polyether ionophore, laidlomycin, and several acyl derivatives were tested for their ability to favorably alter fermentation in two types of in vitro rumen fluid incubations. Dose response data were used to estimate the concentration (microgram/ml) of each ionophore required for either 50% maximal enhancement of propionic acid production (EC50) or 50% maximal inhibition of lactic acid production (IC50). Acylation of laidlomycin with straight-chain acyl groups from two to 12 carbon atoms tended to improve the potency of laidlomycin, especially for inhibiting lactic acid production. Comparative incubations using laidlomycin butyrate, laidlomycin and monensin indicated that both laidlomycin butyrate (EC50 = .3) and monensin (EC50 = .7) were more potent enhancers of propionic acid production than laidlomycin (EC50 = 2.0; P less than .05). Laidlomycin butyrate (IC50 = .3) was a more potent inhibitor of lactic acid production than either laidlomycin (IC50 = 1.8) or monensin (IC50 = 1.3; P less than .05). In a continuous culture experiment, three chemostats each received laidlomycin butyrate or monensin at the rate of .5 micrograms/ml of effluent/d while two flasks remained as control. Propionic acid production was increased (P less than .01) from 22.9 mmol/d in control flasks to 30.5 and 33.7 mmol/d in flasks treated with monensin and laidlomycin butyrate, respectively. Concomitant decreases in production rates of acetic, butyric and isovaleric acids also were observed (P less than .01). Thirty-six steers were used in a 56-d trial to evaluate effects of laidlomycin butyrate and monensin, at 33 mg/kg of diet, on feedlot performance.(ABSTRACT TRUNCATED AT 250 WORDS)     

日粮中添加玉米油对肉牛瘤胃发酵的影响

3头装有瘤胃瘘管的成年杂种牛 ,按 3× 3拉丁方试验设计 ,饲以添加 0 %、4 %和 8%玉米油的稻草和精料混合料 ( 2 1 )日粮。在饲喂后 2、4、6、8h采集瘤胃液样品 ,分别测定瘤胃液pH值、NH3-N和VFA浓度。结果表明 ,添加 4 %和 8%玉米油对瘤胃液pH值、NH3-N浓度没有显著影响 (P >0 .0 5) ;添加玉米油 4 %对瘤胃总VFA浓度没有显著影响 (P >0 .0 5) ,但添加 8%玉米油使瘤胃总VFA和乙酸浓度显著下降 (P <0 .0 5)。添加 8%以下的玉米油对丙酸、丁酸浓度没有影响 (P >0 .0 5) ,结果使乙酸 /丙酸比值从 3.75分别下降到 3.2 6和 3.1 4 (P <0 .0 5)。     

Effect of acid and alkali treatment of soybean meal on nitrogen utilization by ruminants

Soybean meal (SBM) was treated with acid or alkali to determine effects on N solubility, in vitro NH3-N accumulation, in situ N degradability, and N digestion and retention in growing lambs. The following SBM treatments resulted in decreased (P less than .05) N solubility and in vitro NH3-N accumulation compared with control SBM: spraying with 2.5 or 5% acetic or propionic acid, soaking in .5 N HCl, .5 N NaOH or .5 N propionic acid followed by air drying, and soaking in H2O, .5 N HCl or .5 N propionic acid followed by drying at 100 C. In situ residual N was determined for SBM subjected to the above treatments. Soybean meal sprayed with 2.5 or 5% acetic or propionic acid had greater (P less than .05) in situ residual N after 4, 8 and 12 h of incubation than control SBM. Soybean meal soaked in .5 N HCl or .5 N NaOH and air-dried, and soaked in H2O, .5 N propionic acid or .5 N HCl and dried at 100 C had greater (P less than .05) in situ residual N after 4, 8, 12 and 24 h of incubation than control SBM. In a lamb N balance trial, SBM treated by spraying with 5% acetic or propionic acid or by soaking in .5 N NaOH did not result in reduced N digestion compared to control SBM. Feeding SBM soaked in .5 N NaOH resulted in a 39% increase (P less than .05) in N retention compared with control SBM (5.21 vs 3.74 g/d, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of ruminal infusion of glucose, volatile fatty acids and hydrochloric acid on mineral metabolism in sheep

Two experiments were conducted to study the effects of alterations in ruminal pH and volatile fatty acid (VFA) concentrations on utilization of Mg and other minerals. In Exp. 1, two metabolism trials were conducted with 12 ruminally cannulated crossbred wethers fed 800 g/d of orchard-grass (Dactylis glomerata, L.) hay. After each feeding, wethers were ruminally infused with 500 ml (4.2 ml/min) or either 1) deionized water, 2) 40% (w/v) glucose solution, 3) .26 M propionic and .17 M butyric acid solution or 4) .35 M HCl. The pH of the VFA solution was adjusted to 6.8 with 10N NaOH. In Exp. 2, a metabolism trial was conducted with 12 ruminally cannulated crossbred wethers fed 600 g of orchard-grass hay and infused with a buffered VFA solution prepared as in Exp. 1 or with an unbuffered solution. In both experiments each trial consisted of a 5-d adaption period followed by four 5-d collections of feed, feces and urine. Compared with the glucose treatment, infusion of the buffered VFA solution produced similar acetic and propionic and higher (P less than .05) butyric acid concentrations (Exp. 1). The HCl solution produced changes in ruminal and pH values similar to those of the glucose infusion. In Exp. 1, apparent absorption of Mg was increased over twofold by the glucose infusion (P less than .05), but the other infusions had no effect. Apparent absorption of P was decreased (P less than .05) by HCl infusion, and K absorption was decreased by HCl and glucose infusions. In Exp. 2, infusion of the unbuffered VFA solution decreased apparent Mg absorption by 15.7%, compared with infusion of the buffered solution. These experiments suggest that the increased Mg absorption observed with carbohydrate supplementation is not due to alterations in ruminal pH or VFA levels.     

Effect of pH on in vitro ruminal conversion of L-tryptophan to 3-methylindole and indole

Three in vitro experiments were conducted to determine the effects of pH on ruminal conversion of L-tryptophan (TRP) to 3-methylindole (3-MI) and indole (IND). Experiment 1 involved 2 closed-system incubations, each with triplicate replications of buffered ruminal fluid at initial pH of 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0. Highest molar conversions of TRP to 3-MI were 61.5 +/- 2.7% and 64.3 +/- 0.8% at initial pH treatments of 7.5 and 7.0 (final pH 7.3 and 6.9) for the 2 incubations, respectively. Experiment 2 used duplicate continuous cultures at each of 4 pH treatments. Following a common 5-day pretreatment period, effluent pH averaged 5.6, 6.1, 6.5, and 6.9 for the respective treatments. Data for 4 subsequent 5-day time periods showed production of 3-MI was affected by pH treatment (P less than 0.01), time (P greater than 0.01), and treatment X time (P less than 0.01); conversion of TRP to 3-MI reached 78% at pH 6.9 and decreased to less than 1% at pH 5.6. Production of IND was not related to pH treatment (P greater than 0.10). Total moles of volatile fatty acid (VFA) carbon produced showed a pH treatment X time interaction (P less than 0.01) which reflected a trend toward decreasing VFA production at lower pH and increasing VFA production at higher pH. Experiment 3 consisted of 2 pH treatments with additional continuous culture fermenters.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of dairy food processing wash water solids as a protein source: III. Nitrogen utilization by heifers fed medium-concentrate diets

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.     

Effect of pectinase on rumen fermentation in sheep and lambs

In trial with adult wethers and weaned lambs the effect of enzymatic preparation Pektofoetidin G3x (mostly pectinase and cellulase) on rumen fermentation was studied. After 4 weeks of Pektofoetidin G3x application (0.54 g per day and animal) to adult wethers no statistically significant differences in total volatile fatty acids (VFA), acetic acid, propionic acid, butyric acid, ammonia in the rumen contents and urea in blood were determined between control and enzyme treated group. In comparison of fermentation parameters in wethers (mean of 1-3 hours after feeding) and lambs (2-3 hours after feeding) the significant differences in mol % of acetic acid (63.3 in control, 54.6 in experimental group, P less than 0.01), propionic acid (24.6, vs. 31.3, P less than 0.001), acetate: proprionate ratio (2.54, vs. 1.77, P less than 0.01) and in energy efficiency of VFA production (76.0%, vs. 79.1%, P less than 0.001) were determined. These differences between wethers and lambs suggest more intensive fermentation in lambs than in adult sheep. On the basis of these results it is possible to suggest, that in adult animals the efficiency of application of enzymatic preparations is low. In utilization of enzymatic preparations more important role, probably, is that of ruminal ecosystem itself, that, if once fully developed, is perfectly resistant to biotechnological interferences.     

不同热应激条件下添加二氢吡啶对奶牛瘤胃发酵功能的影响

[目的]研究不同热应激条件下添加二氢吡啶对奶牛瘤胃发酵功能的影响。[方法]试验选取6头三胎次泌乳中期中国荷斯坦奶牛,采用自身前后对照,分为4个时期:无应激且不添加二氢吡啶(NS-ND)、无应激添加二氢吡啶(NS-D)、应激但不添加二氢吡啶(S-ND)、应激且添加二氢吡啶(S-D),二氢吡啶添加量为每头牛3.0g/d(即0.6mg/kg体重)。[结果]S-ND时期与NS-ND时期相比,瘤胃液中pH值降低,NH3-N浓度极显著升高(P0.01),瘤胃液内挥发性脂肪酸(VFA)的浓度显著下降(P0.01),其中乙酸的百分比含量下降,丙酸和丁酸的百分比含量升高,但差异不显著(P0.05),乙丙比呈稍下降趋势,差异不显著(P=0.13);应激和无应激时期添加二氢吡啶后,有使瘤胃液pH降低的趋势,NH3-N浓度均显著降低(P0.01),VFA的浓度显著提高(P0.01),乙丙比显著增高(P0.01)。[结论]添加二氢吡啶对提高热应激时期奶牛瘤胃的发酵功能有良好效果。     

Influence of meal frequency on postprandial variations in the production and absorption of volatile fatty acids in the digestive tract of conscious pigs

Five Large White pigs of 62.2 +/- 1.4 kg mean body weight were fitted with permanent catheters in the portal vein and carotid artery and with an electromagnetic flow probe around the portal vein to study the absorption of volatile fatty acids (VFA) by measuring the concentration of these metabolites in hourly blood samples, and by determining the portal blood flow rate for a period of 12 h after intake of a single 800-g meal (6% crude fiber) preceded by 12 or 24 h of fasting. The portal concentration of VFA mixture always highly exceeded the arterial concentration. The arterial concentrations of propionic, butyric, valeric and isovaleric acids were nearly null, accounting for an almost complete uptake of these VFA by the liver. Acetic acid also was taken up, but to a lesser extent. Total VFA absorption during 12 h was 64% higher (P less than .05) after 12 h (1,160 +/- 100 mmol/12 h) than after 24 h of preprandial fasting (740 +/- 83 mmol/12 h). It increased after the meal (P less than .05) from 82.3 +/- 7.8 mmol/h between the first and fourth hour to 107.8 +/- 7.5 mmol/h between the fifth and tenth hour when the preprandial fasting lasted 12 h; a nonsignificant increase also was found when fasting prior to the meal lasted 24 h. The composition of the VFA mixture was not modified by the length of preprandial fasting. With this type of diet there was a large predominance of acetic acid (52%) followed by propionic and butyric acids (36 and 8.5%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Forestomach epithelial receptor activation by rumen fluids from sheep given intraruminal infusions of volatile fatty acids

Forty-four reticuloruminal epithelial receptors were tested with rumen fluids obtained from 12 sheep before they were intraruminally infused with 4.0M acetic acid (8 sheep) or 4.0M butyric acid (4 sheep; preinfusion rumen fluid) and with rumen fluids obtained at the onset of ruminal stasis (abolition rumen fluid). The preinfusion rumen fluids from the 8 acetic acid-infused sheep (mean pH, 6.55) contained 1.7 mM nondissociated volatile fatty acids (VFA)/L and excited none of the 25 receptors tested. Preinfusion rumen fluids from the 4 butyric acid-infused sheep (mean pH, 6.98) contained 0.3 mM nondissociated VFA/L and also did not evoke responses in any of the 19 receptors tested. Abolition rumen fluids from sheep treated with acetic acid excited 17 of the 25 receptors tested and contained 89.4 mM nondissociated VFA/L, of which nondissociated acetic acid comprised 85.0 mM/L. Abolition rumen fluids from sheep treated with butyric acid activated 14 of the 19 receptors tested and contained 61.1 mM nondissociated VFA/L, of which 38.7 mM/L was nondissociated butyric acid. Preinfusion rumen fluids whose pH values were adjusted to that of abolition rumen fluids with HCl contained nondissociated VFA levels ranging from 16.3 mM/L (acetic acid-treated sheep) to 20.6 mM/L (butyric acid-treated sheep) and elicited responses in 4 of 30 receptors tested. Preinfusion rumen fluids whose pH values were adjusted to the pH value of abolition rumen fluid with acetic acid contained 29.5 mM nondissociated VFA/L and excited 7 of 13 tested receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of decoquinate on ruminal fermentation, diet digestibility and cattle performance

Three experiments utilizing three Holstein steers (235 and 299 kg avg body weight for Exp. 1 and 2, respectively) were conducted to evaluate the effects of decoquinate, a synthetic coccidiostat, on ruminal fermentation, diet digestibility and performance of steers fed a finishing diet containing monensin and tylosin. Experiment 1 utilized a 70% forage diet, whereas Exp. 2 utilized a 20% forage diet. Each experiment was a 3 X 3 Latin-square design with treatments being 0, .5 and 5 mg decoquinate/kg body weight. Ruminal fermentation characteristics, water kinetics and blood constituents were measured on d 11 of each period, and zero-time volatile fatty acid (VFA) production was measured at 3 and 6 h post-feeding on d 12 to 14. No changes were seen in plasma glucose or L-lactate, ruminal pH, NH3-N or ruminal L-lactate for either experiment. Dry matter digestibility was depressed (P less than .05) at the .5- and 5-mg levels of decoquinate in Exp. 1, but dry matter digestibility was not affected in Exp. 2. No changes were seen in ruminal volume, outflow or total VFA concentration for either experiment. Molar proportions of VFA were not affected in Exp. 1, but the proportions of isobutyrate and butyrate decreased (P less than .05) at the 5-mg level of decoquinate in Exp. 2. Volatile fatty acid production was not changed in Exp. 1, but butyrate production was decreased (P less than .05) at the 5-mg level in Exp. 2. Experiment 3 involved 135 crossbred steers (259 kg avg initial wt), which were stratified by weight into 12 pens.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of Particle Size of Feed on Rumen Fermentation of Sheep Using the Rumen Simulation Technique (Rusitec)

This experiment was aimed to investigate the effects of different particle sizes of feeds on rumen fermentation using the rumen simulation technique (Rusitec). There were two treatments (5 and 0.45 mm) with 4 replicates per group. After 10 days'adaptations,the fermentation parameters were determined for 2 days,and the total gas production,methane production and fermentation parameters were determined. The results showed that the total gas production of 5 nm group was extremely significantly higher than that of 0.45 nm group (P <0.01),while methane production of the two group was no significant difference (P >0.05).The ruminal fluid pH at 6 h,acetic acid at 6 and 9 h, isobutyric acid at 6 h, acetic acid to propionic acid ratio at 12 h,butyric acid at 6 h,total volatile fatty acids at 0,12 h and total nitrogen at 6 and 9 h in 5 mm group were significantly or extremely significantly greater than those in 0.45 mm group (P <0.05;P <0.01). While propionic acid at 12 h and valeric acid at 3,6,9 and 12 h in 5 mm group were significantly or extremely significantly lower than that in 0.45 mm group (P <0.05;P <0.01).Other parameters were not significantly affected by particle size (P >0.05). These results certified that the particle size of feeds in Rusitec did affected the rumen fermentation. Large size improved the gas production,acetic acid to propionic acid ratio,total volatile fatty acids and total nitrogen cotents.     

用Rusitec系统研究两种粒度日粮对绵羊瘤胃发酵特性的影响

试验旨在应用Rusitec系统研究不同粒度日粮对绵羊瘤胃发酵特性的影响。试验分为两个处理组,日粮颗粒分别为5和0.45 mm,每个处理4个重复,适应期10 d,采样期2 d,测定不同时间发酵液总产气量、甲烷产量及发酵参数。结果显示,5 mm颗粒组的总产气量极显著高于0.45 mm颗粒组（P＜0.01）,甲烷产量不受粒度的影响（P＞0.05）;5 mm颗粒组投料后6 h的pH、6和9 h的乙酸、6 h的异丁酸、12 h的乙酸/丙酸、0和12 h的总挥发性脂肪酸、6和9 h的总氮均显著或极显著大于0.45 mm颗粒组（P＜0.05;P＜0.01）,而5 mm颗粒组12 h的丙酸及3、6、9、12 h戊酸则显著或极显著小于0.45 mm组（P＜0.05;P＜0.01）,不同粒度对其余指标没有显著影响（P＞0.05）。由此可知,人工瘤胃试验中日粮的不同粒度可影响发酵特性,较大颗粒有较高的总产气量、乙酸、乙酸/丙酸、总挥发性脂肪酸和总氮含量。     

添加不同水平阴离子盐对人工瘤胃液理化指标的影响

本试验采用人工瘤胃模拟装置研究了添加不同水平阴离子盐0、-50mEq/kg、-100mEq/kg和-150mEq/kg的日粮对瘤胃消化代谢的影响。通过对瘤胃液pH值、NH3-N、VFA浓度的测定,结果表明,添加阴离子盐水平在-150mEq/kg内,对瘤胃pH值和氨氮浓度有一定影响,但差异不显著(p>0.05);当添加水平在-100mEq/kg和-150mEq/kg时,对乙酸浓度、丙酸浓度及乙酸/丙酸比例影响差异均为显著(P<0.05)。     

Effects of calcium soaps of long-chain fatty acids on feedlot performance, carcass characteristics and ruminal metabolism of steers

Two trials were conducted to determine the effects of calcium soaps of long-chain fatty acids (calcium soap) on feedlot performance, diet digestibility, carcass characteristics and ruminal metabolism of steers fed diets (85% concentrate:15% corn silage) containing 0, 2, 4 or 6% calcium soap. In Trial 1, increasing calcium soap decreased (P less than .05) DM, CP and gross energy intake but increased total fatty acid intake. Feed to gain ratio tended to improve with increased calcium soap; gross energy conversion was not affected (P greater than .05) by diet. Average daily gain and hot carcass weight decreased (P less than .05) with addition of calcium soap; other carcass characteristics were not affected (P greater than .05). Apparent digestibilities of DM, N, energy and ash were not affected (P greater than .05) by calcium soap. Neutral detergent fiber digestibility increased linearly (P less than .08) with increasing calcium soap, whereas digestibility of total fatty acids was affected quadratically (P less than .05); fatty acid digestibility was similar among 0, 2 and 4% calcium soap diets but decreased for the 6% calcium soap diet. In Trial 2, increased calcium soap did not affect (P greater than .05) ruminal VFA concentrations, pH or in sacco NDF disappearance of orchardgrass following 12, 24 and 48 h of incubation. Calcium soap increased (P less than .07) ruminal concentrations of calcium soap fatty acids at 1, 2, 4 and 8 h postfeeding. Calcium soap did not improve performance of feedlot cattle fed high-concentrate diets. Further, calcium soap did not affect ruminal fermentation and did not dissociate significantly even when ruminal pH was below 6 for extended periods of time.     

Effects of the essential oil cyclodextrin complexes on ruminal methane production in vitro

The effects of including essential oil cyclodextrin (CD) complexes on ruminal methane and hydrogen production, volatile fatty acid (VFA) and protozoa were studied in vitro. The essential oil CD complexes used in the present study were both αCD and βCD with cineol, eucalyptus, menthol, peppermint, thyme and wasabi. Diluted rumen fluid (60 mL) was incubated anaerobically at 38°C for 6 h with the essential oil CD complex (1–40 mg as oil). Eucalyptus‐αCD reduced methane production by 40% with 10 mg as oil along with decreasing the protozoal number and increasing total VFA and proportion of propionic acid. Both wasabi‐αCD and wasabi‐βCD reduced methane production by 85% and 97%, respectively, with 10 mg as oil, though they increased hydrogen production notably. The protozoal number was unchanged by wasabi‐βCD and decreased to 50% by wasabi‐αCD. Propionic acid was increased by both wasabi‐αCD and wasabi‐βCD. The other essential oil‐CD showed no significant effect on reducing methane production. The combined use of 20 mM of fumaric acid with wasabi‐αCD (1 mg as oil) caused about a 50% depression of methane production compared to the control without increasing hydrogen production. Fumaric acid was more effective than malic acid in reducing methane production. The addition of eucalyptus‐αCD, wasabi‐αCD or wasabi‐βCD together with organic acid to rumen fluid turned out to be effective for reducing methane production with no increase in hydrogen production.     

Comparative digestion, rumen fermentation and kinetics of forage diets by steers and wethers

Four rumen fistulated wether and beef steers were used to evaluate differences in dry matter digestibility (DMD) between cattle and sheep. They were fed either perennial ryegrass or switchgrass hay at an ad libitum or restricted level for four experimental periods. Significant ruminant species X forage and ruminant species X level of intake (P less than .05) interactions were observed for digestible dry matter. The steers digested the switchgrass 7 percentage units greater than the wethers while ryegrass was digested equally. Digestibility differences between the steers and wethers were 6 percentage units at the ad libitum level of intake and 1 unit at the restricted level of intake. Crude protein digestibility tended to be greater (P less than .10) for sheep with a 7 unit difference for switchgrass and a 3 unit difference for ryegrass. The mean ruminal solids retention time of the digesta was approximately (P less than .01) 50% greater (26.0 vs 17.4 h) in cattle, with no difference in ruminal liquid dilution rate (LD) between animal species. Total ruminal volatile fatty acid concentration differed (P less than .01) with level of intake; however, no influence due to intake on the molar proportion of acetate (P greater than .10) or propionate (P greater than .10) was evident in spite of a difference (P less than .01) in LD. Rumen pH (P less than .05) and osmolality (P less than .01) were affected by both level of intake and forage, with the ryegrass and high level of intake decreasing pH and increasing osmolality.(ABSTRACT TRUNCATED AT 250 WORDS)