Effects of buffers on ruminal rate of passage and degradation of soybean meal in steers

Eight rumen-fistulated steers were randomly assigned to medium- and high-concentrate diets supplemented with 0, .75, 2.5 and 5% of either sodium bicarbonate or an artificial saliva salts mixture. Each animal was fed for 21 d at 75 g dry matter/kg body weight . 75. Rates of soybean meal (SBM) degradation were predicted by adjusting digestion rates in nylon bags with respective passage rates of chromium-mordanted SBM particles. Measures of rumen fermentation were made during the incubation period. Liquid dilution rate was determined with 51Cr-EDTA. The high-concentrate diet produced higher (P less than .05) liquid dilution rates than the medium-concentrate diet, but there were no differences in response to the two buffers (P greater than .05). The liquid dilution rates averaged across diets for 0, .75, 2.5 and 5% levels of buffer were 6.2, 6.3, 8.5 and 8.7%/h (SE = .03) and passage rates for SBM were 5.2, 5.2, 6.5 and 6.7%/h (SE = .025). The 2.5 and 5% levels of buffer increased the rate of disappearance of SBM from the nylon bags and buffers fed at these levels also increased rumen pH and NH3-N concentration. Rumen pH was correlated with N disappearance from the nylon bag (r = .903, P less than .05). Buffer levels did not affect degradation rates of SBM.     

乙酸钠对西门塔尔牛豆粕营养物质瘤胃降解率的影响

选用4头装有永久性瘤胃瘘管,年龄4岁,体重约420kg,体况良好的西门塔尔阉牛。采用4×4拉丁方设计．以混合精料和玉米秸秆为基础日粮,研究乙酸钠添加量（0、200、400和600g／d）对瘤胃豆粕营养物质有效降解率的影响。结果表明：添加乙酸钠对豆粕DM、OM瘤胃有效降解率差异不显著（P〉0．05）。400g／d和600g／d组豆粕CP瘤胃有效降解率显著降低（P〈0．05）。因此推断乙酸钠的适宜添加水平为400g／d。     

Nitrogen utilization and ruminal fermentation in steers fed soybean meal treated with formaldehyde

Four rumen-fistulated steers averaging 400 kg in body weight were used in a 4 X 4 Latin square arrangement with 18-d periods to investigate the effect of treating soybean meal (SBM) with formaldehyde on nitrogen (N) utilization and ruminal fermentation. Experimental diets, on a dry matter basis, consisted of 42% corn silage, 48.5% cracked corn-mineral mixture and 9.5% SBM treated with 0, .3, .6 or .9% formaldehyde by weight. Dry matter and organic matter digestibilities were not affected by treatment. Formaldehyde treatment of SBM resulted in a linear decrease in N digestibility (P less than .005) and urinary N excretion (P less than .01) and a quadratic increase (P less than .05) in N retention. The depression in apparent N digestibility was small when SBM was treated with .3% formaldehyde. This level of formaldehyde treatment also had little effect on in vitro enzymatic hydrolysis of SBM. Ruminal ammonia-N concentrations were lower (P less than .05) in steers fed formaldehyde-treated SBM. Ruminal pH was lower (P less than .05) at 6 and 8 h postfeeding while volatile fatty acid concentrations were higher (P less than .05) at 8 and 12 h postfeeding for steers fed untreated SBM. Propionic acid (mol/100 mol) decreased linearly (P less than .05) with increasing level of formaldehyde treatment. Urea-N concentrations in plasma were decreased (P less than .001) and plasma-free essential amino acid concentrations were increased (P less than .10) by formaldehyde treatment. Ruminal disappearance of N from polyester bags containing the SBM supplements was greatly reduced (P less than .005) by formaldehyde treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

瘤胃内容物发酵对豆粕蛋白质品质及菌群组成的影响

本试验采用体外发酵技术,选用瘤胃内容物(瘤胃液)作为混合菌源对豆粕进行固态发酵处理,瘤胃液接种量为5%,料水比为1∶1,39℃,厌氧发酵72 h。对发酵前后豆粕营养特性进行分析,并对发酵前后豆粕微生物指标和pH值进行测定。结果表明,豆粕经瘤胃液发酵后,氨基酸的含量比发酵前提高了3%,大分子量的蛋白质得到降解,小分子多肽明显增加。此外,发酵豆粕的pH值显著下降(P<0.05),菌群结构上菌落总数极显著增加,霉菌和大肠杆菌菌群显著降低,而有益的乳酸菌极显著上升(P<0.05)。本试验证实了瘤胃内容物可作为豆粕发酵处理的有效菌源,为开辟新的饲料资源提供参考。     

Effects of microwave irradiation on ruminal protein degradation and intestinal digestibility of cottonseed meal

The objectives of this study were to determine the effects of microwave irradiation on ruminal degradability and intestinal digestibility of crude protein (CP) and to monitor the fate of true proteins of cottonseed meal (CSM) in the rumen. Duplicate nylon bags of untreated or irradiated CSM (microwave power of 800 W for 2, 4 and 6 min) were suspended in the rumen of four non-lactating Holstein cows for up to 48 h, and resulting data were fitted to non-linear degradation model to calculate degradation parameters of CP. Proteins of untreated and treated CSM bag residues were fractionated by gel electrophoresis. Intestinal digestibility of CP was measured using the mobile nylon bag technique. From in situ results, microwave irradiation decreased (P < 0.05) the water soluble fraction and degradation rate, but increased the potentially degradable fraction of CP. The effective degradability of CP decreased (P < 0.05) as processing period increased. Irradiation for 2 and 4 min increased (P < 0.05) intestinal digestibility of ruminally undegraded CP, but extending to 6 min lowered (P < 0.05) the beneficial effect that 4 min had on intestinal CP digestibility. Electrophoretic results indicated that globulin 9S in untreated CSM (whereas globulin 9S, globulin 5S and albumin 2S in microwave irradiated CSM) make the bulk of escaped protein. Based upon these results, microwave irradiation at a power of 800 W for 4 min had the greatest potential to increase digestible undegraded protein.     

Effects of heat and alcohol treatments of soybean meal on nitrogen utilization by sheep

Soybean meal (SBM) was treated with aqueous solutions of ethanol or propanol at room temperature or at 80 C to study treatment effects on SBM-N solubility and utilization by sheep. Soybean meal was soaked in an excess of 70% (v/v) ethanol at 80 C (ET-80), 70% ethanol at 23 C (ET-23) or 70% propanol at 80 C (PR-80). Nontreated SBM and nontreated SBM heated at 80 C without alcohol treatment (NT-80) served as controls. Nitrogen solubility in McDougall's buffer was lowest (P less than .05) for PR-80 and ET-80 (2.2 and 4.7% of total N, respectively), intermediate (P less than .05) for ET-23 (9.0%), greater (P less than .05) for nontreated SBM (36.2%) and highest for NT-80 (40.2%). In an situ study using three ruminally cannulated cows and two bags per treatment per animal per removal time, more (P less than .05) N remained in in situ bags after 3, 6, 9 and 12 h incubation for ET-23, ET-80 and PR-80 than for nontreated SBM and NT-80. A lamb metabolism trial, using 15 lambs in each of two periods, compared nontreated SBM, ET-23, ET-80, PR-80 and urea as N supplements. Nitrogen retention was higher (P less than .02) for lambs fed SBM treatments compared with urea. When the same N supplements were fed to wethers in a 5 X 5 Latin square experiment and duodenal N flow was measured, non-ammonia non-bacterial N flow was higher (P less than .07) for wethers fed SBM treatments than for wethers fed urea.(ABSTRACT TRUNCATED AT 250 WORDS)     

Apparent ruminal degradation and rumen escape of soluble nitrogen fractions in grass and grass silage administered intraruminally to lactating dairy cows

The main objective of this study was to investigate in vivo ruminal degradation and rumen escape of soluble N fractions in grass and grass silage. Soluble protein and long-chain peptides (PLP), small peptides (SP) and free AA (FAA) were obtained from fresh grass and grass silages fertilized with different levels of N. Soluble extracts from the forages were pulse dosed into the rumen of three cannulated lactating dairy cows, and a simple or complex model was used to examine the kinetics of the soluble N fractions in the rumen. When soluble extracts from silage were investigated, pulse dosages of total nonammonia N (NAN) were 21, 27, and 32 g, while for fresh grass only dosages of 20 g were ruminally administered. In the silage extracts, mean proportions of PLP-N, SP-N, and FAA-N in the NAN were 30, 52, and 18%, respectively, whereas in the fresh grass the corresponding values were 67, 20, and 13%. From silage extracts, all three soluble N fractions showed a linear decrease (P < 0.05) in degradation rate and an increase (P < 0.05) in ruminal escape with increasing dosage. In silage, mean degradation rates, parameterized from the complex model, were 230, 214, and 334%/h for PLP-N, SP-N, and FAA-N, respectively, and the ruminal escape was highest (P < 0.05) for SP-N (11.2% of dose) and lowest (P < 0.05) for FAA-N (5.0% of dose). No differences in degradation rate and ruminal escape between fresh grass and silage were observed. However, the proportion of N dose converted to ammonia was only 24% in the fresh grass, whereas for the silages a mean value of 76% was found. From this study, it is concluded that a significant amount of dietary soluble N escapes ruminal degradation, and thus contributes to the intestinal AA supply. Moreover, if the main aim is to study degradation kinetics of individual N fractions, a complex model should be used in the evaluation. This model can also be used to study ruminal synchronization of N and energy for microbial growth.     

固态发酵工艺对豆粕蛋白质降解度影响的研究

以普通豆粕、挤压豆粕、膨化豆粕为发酵材料,以米曲霉、枯草芽孢杆菌和酿酒酵母为菌种,以三个不同加水量组合为条件,采用L9(34)正交试验设计,设置空列和两次重复,检测蛋白质水解度、酸溶蛋白和游离氨基酸含量,进行数据的极差、方差分析和多重比较,寻找固态发酵豆粕工艺中前处理方法、菌种组合与加水量组合对提高蛋白质降解度的优化参数组合。对于提高发酵豆粕蛋白质水解度,膨化豆粕工艺优于普通豆粕和挤压豆粕,米曲霉菌种优于枯草芽胞杆菌及其与米曲霉两者的组合,较高加水量优于低加水量;酸溶蛋白和游离氨基酸含量与蛋白质水解度具有高度的一致性,可以使用蛋白质水解度作为蛋白质降解度的评价指标;对于蛋白质降解速度,好氧发酵是厌氧发酵的5.3倍。综合试验结果得到的优化工艺参数组合为A3B1C3。     

Effects of supplementing prairie hay with corn and soybean meal on intake, digestion, and ruminal measurements by beef steers

Prairie hay supplemented with various amounts of corn and soybean meal was fed to steers in two experiments. Effects of supplementation on hay OM intake, digestion, and ruminal fermentation and kinetics were measured. A preliminary study was conducted to attain accurate values for OM intake and digestibility of prairie hay to be used in ration formulation using the NRC (1996) level 1 model. Ten steers (284 +/- 9 kg) given ad libitum access to chopped prairie hay (75% NDF, 6% CP) were supplemented with dry-rolled corn (0.75% of BW/d) plus soybean meal (0.25% of BW/d). Hay OM intake was 1.85% of BW and hay OM digestibility was 48%. Based on results from the preliminary study, eight ruminally cannulated beef steers (317 +/- 25 kg) received a sequence of eight different supplementation combinations (2 x 4 factorial arrangement of treatments). These supplements consisted of dry-rolled corn at either 0 or 0.75% of BW (DM basis) daily combined with one of four amounts of added soybean meal to provide between 0 and 1.3 g of degradable intake protein (DIP)/kg of BW. After supplements had been fed for 10 d, feces were collected for 4 d. Intake of hay and total OM increased quadratically (P < 0.01) in response to added DIP with or without supplemental corn. Hay OM digestibility increased quadratically (P = 0.03) as DIP was added when corn was fed in the supplement. Intake of digestible OM was greater (P < 0.01) with than without corn supplementation. Increasing DIP increased (P < 0.01) digestible OM intake regardless of whether corn was fed. Inadequate ruminally degraded protein in grain-based supplements decreased forage intake, digestibility, and energy intake of cattle fed low-quality prairie hay. Providing adequate supplemental DIP to meet total diet DIP needs seemed to overcome negative associative effects typically found from supplementing low-quality forages with large quantities of low-protein, high-starch feeds.     

Effects of different heat treatments during processing of soybean meal on nursery and growing pig performance

Four soybean meals (SBM) were manufactured in a commercial solvent-extraction plant to give a much wider range in heat treatment than is usually found among commercially available SBM. The SBM were designated in ascending order of heat treatment as Under, Normal, Over and Rumen Escape. The nutritive value of the four meals was evaluated in a series of five feeding trials using 458 pigs: two performance and two diet preference trials with pigs weaned at 4 wk of age and one performance trial with growing pigs (17.4 kg initial weight were conducted). In both nursery and grower trials, there were no differences (P greater than .10) in performance of pigs fed the four meals. However, in the nursery trials, the severely heated meal (Rumen Escape) supported slightly lower gains (6.4%) and less desirable feed efficiency (3.5%) than the average of the other three meals. Growing pig performance was essentially the same for all meals. This suggests that older pigs either used the Rumen Escape meal more effectively than nursery pigs, or the Rumen Escape diet contained adequate digestible lysine for 17.4-kg pigs to grow optimally. In the preference studies, pigs selected between Normal- and Rumen Escape-supplemented diets. Pigs consumed 63 and 62% of the Normal diet in preference trials 1 and 2, but these differences were not significant (P greater than .10) due to the large variation among pens. These data suggest that the range of heat treatment normally found among commercially available SBM (Under, Normal and Over meals) has no effect on the nutritive value of the meal for swine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of different heat treatments during processing on nutrient digestibility of soybean meal in growing swine

Four soybean meals (SBM) were prepared in a commercial solvent-extraction plant to give a much wider range in heat treatment than is usually found among commercially available SBM. The meals were designated in ascending order of heat treatment as Under, Normal, Over and Rumen Escape. The Normal meal was processed using standard operating conditions. The Under meal received less heat treatment by reducing the steam pressure and retention time in the desolventizer-toaster. Over and Rumen Escape meals received further heat treatment in an additional four-compartment toaster. The Over meal received less heat treatment than the Rumen Escape meal by reducing steam pressure and retention time in both toasters. Crude protein content was similar for the four meals, but lysine tended to decrease with increasing heat treatment. In general, urease activity, trypsin inhibitor, protein dispersibility index and nitrogen solubility index decreased with increasing heat treatment. The +a Hunterlab color values increased as heat treatment increased. Apparent ileal digestibility of N and amino acids were similar for all meals (P greater than .05); however lysine digestibility for the Rumen Escape meal was 3.3 percentage units lower than the average of the lesser-heated meals. Energy digestibilities and nitrogen balance data were also similar (P greater than .05) for the four meals, but the apparent biological value of the Rumen Escape meal was 4.5 percentage units lower than the average of the other meals. There were no differences in nutritional value among the Under, Normal and Over meals, which represent the range in heat treatment usually found among SBM. The Rumen Escape meal, which received more severe heat treatment, tended to have lower nutritional value than the lesser-heated meals.     

甲醛与鲜血处理对全脂大豆粉瘤胃降解率的影响

全脂大豆是优良的蛋白质和能量补充料 ,过瘤胃全脂大豆粉可同时为反刍动物提供过瘤胃蛋白和脂肪 ,这对反刍动物特别是高产泌乳奶牛有重要意义 :在提高泌乳量的同时 ,避免因单纯添加脂肪等能量饲料带来乳蛋白下降问题 ,且不干扰瘤胃正常发酵和能氮平衡 ,也可避免优质蛋白质在瘤胃的发酵损失。本试验通过甲醛、鲜血单独或复合处理对全脂大豆粉实施保护处理 ,以期找到安全有效的大豆粉过瘤胃保护措施。1　材料与方法1 1　试验原料　大豆为市场购买 ,粗蛋白质含量为 40 4% ,脂肪含量为 2 0 7%。甲醛为重庆东方试剂厂生产。新鲜猪血采自本地肉…     

Effects of ruminal escape proteins and canola meal on nitrogen utilization by growing lambs

The effects of ruminal escape proteins and canola meal (CM) on N utilization by growing lambs were evaluated in two experiments. In both experiments, seven supplemental dietary protein treatments were fed. For each of these protein treatments a 3 x 3 Latin square metabolism trial was conducted, using two sets of three lambs and three periods. Within square treatments were 1.4, 1.7 and 2.0 times maintenance intake levels. In Exp. 1, protein treatments were control (7.0% CP, DM basis), urea fed at 9.5 or 12% dietary CP, CM fed at 9.5 or 12% dietary CP and a 50:50 (N basis) mixture of blood meal/corn gluten meal (BC) fed at 9.5 or 12% dietary CP. In Exp. 2, protein treatments were urea, 64% urea and 36% BC (all mixtures on a N basis), 36% urea and 64% BC, BC, 50% CM and 50% BC (CM/BC), CM and soybean meal (SBM), all at 10.5% CP. In Exp. 1, apparent N digestibility (AND) was lower for CM diets than for urea (P = .13) and BC (P less than .05) diets (49.0 vs 50.6 and 51.3%, respectively). Absorbed N was utilized with similar efficiencies for all supplemental protein sources. Dietary CP and digestible protein (DP) were closely related (DP = .879[CP%] -3.66; r2 = .91), indicating that for urea, CM and BC total tract N digestibility was not influenced by theoretical ruminal degradability. In Exp. 2, N balance and N utilization efficiency indicated that the optimal extent of ruminal protein degradation was about 50%. Nitrogen balance was similar for the CM, CM/BC and SBM treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of isobutyrate supplementation on ruminal microflora,rumen enzyme activities and methane emissions in Simmental steers

The objective of this study was to evaluate the effects of isobutyrate supplementation on rumen microflora, enzyme activities and methane emissions in Simmental steers consuming a corn stover‐based diet. Eight ruminally cannulated Simmental steers were used in a replicated 4 × 4 Latin square experiment. The treatments were control (without isobutyrate), low isobutyrate (LIB), moderate isobutyrate (MIB) and high isobutyrate (HIB) with 8.4, 16.8 and 25.2 g isobutyrate per steer per day respectively. Isobutyrate was hand‐mixed into the concentrate portion. Diet consisted of 60% corn stover and 40% concentrate [dry matter (DM) basis]. Dry matter intake (averaged 9 kg/day) was restricted to a maximum of 90% of ad libitum intake. Population of total bacteria, cellulolytic bacteria and anaerobic fungi were linearly increased, whereas that of protozoa and total methanogens was linearly reduced with increasing isobutyrate supplementation. Real‐time PCR quantification of population of Ruminococcus albus, Ruminococcus flavefaciens, Butyrivibrio fibrisolvens and Fibrobacter succinogenes was linearly increased with increasing isobutyrate supplementation. Activities of carboxymethyl cellulase, xylanase and β‐glucosidase were linearly increased, whereas that of protease was linearly reduced. Methane production was linearly decreased with increasing isobutyrate supplementation. Effective degradabilities of cellulose and hemicellulose of corn stover were linearly increased, whereas that of crude protein in diet was linearly decreased with increasing isobutyrate supplementation. The present results indicate that isobutyrate supplemented improved microflora, rumen enzyme activities and methane emissions in steers. It was suggested that the isobutyrate stimulated the digestive micro‐organisms or enzymes in a dose‐dependent manner. In the experimental conditions of this trial, the optimum isobutyrate dose was approximately 16.8 g isobutyrate per steer per day.     

Effects of soybean oil and dietary copper on ruminal and tissue lipid metabolism in finishing steers

An experiment was conducted to determine the effects of Cu and soybean oil (SBO) supplementation on ruminal and tissue lipid metabolism and carcass characteristics in finishing steers. Sixty Angus steers (369.0 +/- 10.1 kg) were stratified by weight and randomly assigned to treatments in a 2 x 2 factorial arrangement, with factors being 0 or 20 mg of supplemental Cu/kg DM from Cu sulfate and 0 or 4% SBO. Steers were fed a high-concentrate basal diet that contained 5.3 mg Cu/kg DM. Average daily gain and feed intake were reduced (P < 0.01) by SBO but were not affected by Cu. Gain:feed ratio was not affected by treatment. Liver Cu concentrations were higher (P < 0.01) in steers receiving supplemental Cu and lower (P < 0.04) in SBO-supplemented steers. Copper supplementation tended to reduce (P < 0.12) and SBO supplementation tended to increase (P < 0.11) serum cholesterol concentrations. Backfat depth was reduced (P < 0.10) by Cu and SBO supplementation. Marbling scores and longissimus muscle lipid content were not affected by Cu supplementation; however, SBO supplementation reduced (P < 0.01) marbling scores. Longissimus muscle polyunsaturated fatty acids tended to be increased (P < 0.14) in Cu-supplemented steers. Longissimus muscle C18-conjugated dienes and the 18:1 trans isomer were increased (P < 0.05) in SBO-supplemented steers. Ruminal fluid 18:3 was increased (P < 0.05) and the 18:1 trans isomer was decreased (P < 0.05) in Cu-supplemented steers. These results indicate that as little as 20 mg of supplemental Cu/kg DM can reduce backfat and may alter lipid metabolism in steers fed high-concentrate diets.     

Effect of monensin on fermentation pattern and soybean protein degradation in the rumen of sheep

The effect of a daily dose of 30 mg Monensin on rumen fermentation pattern and degradation of the crude protein fraction of soybean meal was investigated with sheep. Degradation parameters for soybean meal were measured by the nylon bag technique. Monensin increased propionic acid percentages in the rumen, with a concomitant decrease in acetic- and butyric acid proportions, thus confirming earlier work. Ammonia N concentration in the rumen was also lowered, indicating an inhibitory effect on rumen protein breakdown. However, no effect on degradation rate, degradability and effective degradability (only with one sheep) could be observed. Possible reasons for these findings are discussed. Amino acid analysis on the residues in incubated bags revealed slight changes in amino acid composition, but these changes were considered to be nutritionally unimportant.     

体外条件下葡萄糖处理大豆粕对瘤胃内环境参数的影响

<正>近年来,国外报道过一些糖和加热保护处理可降低优质蛋白质饲料在瘤胃中的降解率,此种方法以糖为保护剂,安全、无污染,在保护方法上是一个突破,改变了以往保护剂如血粉、甲醛等不切合实际应用的不足。本试验旨在用瘤胃液体外培养法评定葡萄糖非酶褐化豆粕对奶牛瘤胃内环境参数的影响,为探索新型饲料蛋白质保护剂提供参考。     

丙酸镁对西门塔尔牛豆粕营养物质瘤胃降解率的影响

选用4头年龄3.5岁、体况良好、体重500kg的中国西门塔尔牛阉牛。采用4×4拉丁方设计,研究日粮添加丙酸镁(100g/d)、丙酸(87g/d)和氧化镁(24g/d)对豆粕干物质(DM)、有机物质(OM)和粗蛋白质(CP)瘤胃降解率的影响。结果表明:日粮中添加丙酸镁、丙酸和氧化镁后对豆粕DM、OM和CP瘤胃有效降解率(P)无显著影响(P>0.05);丙酸镁组豆粕DM和OM快速降解部分(a)较对照组和丙酸组显著提高(P<0.05),丙酸镁组豆粕CP快速降解部分(a)较对照组和氧化镁组显著提高(P<0.05);丙酸组豆粕CP慢速降解部分(b)较对照组和氧化镁组显著降低(P<0.05),氧化镁组豆粕CP慢速降解部分(b)较丙酸镁组显著提高(P<0.05);丙酸组豆粕CP的降解常数(c)较对照组和丙酸镁组显著提高(P<0.05)。丙酸镁提高了豆粕营养物质的瘤胃快速降解部分,但对有效降解率无显著影响。     

瘤胃内丁酸钠灌注对山羊瘤胃发酵类型的影响

本试验通过对青年山羊进行瘤胃丁酸钠灌注研究其对瘤胃发酵类型的影响。6只安装有瘤胃瘘管的山羊分为试验组(n=3)和对照组(n=3),每天饲喂精料2次,并自由采食羊草。试验组每日早晨喂食1 h后开始每天按体重灌注丁酸钠(0.3 g/kg),对照组灌注等量蒸馏水,持续14 d。于灌注期的第1,5,10和14天分别于灌注前1.5 h,灌注后2 h、4 h采集瘤胃液,以气相色谱测定挥发性脂肪酸(VFA)的浓度。结果显示:灌注前、后,试验组瘤胃内乙酸、丙酸摩尔百分比和总挥发性脂肪酸浓度无显著变化;两组之间差异不显著。但试验组丁酸摩尔百分比在灌注2 h后显著上升(P<0.01),4 h后呈下降趋势,次日采食前恢复至正常生理范围。对照组与试验组pH在各采样时间点间基本无显著差异。试验表明青年山羊瘤胃灌注该剂量丁酸钠不引起瘤胃发酵类型的改变。     

硫酸钠对奶牛瘤胃纤维物质降解的影响

本文旨在研究不同添加水平的硫酸钠对泌乳中期奶牛瘤胃纤维物质降解的影响。试验选用4头体重、胎次、产奶量均相近的荷斯坦奶牛,采用4×4拉丁方设计,分4个处理组,在基础日粮基础上分别添加0%(对照组)、0.4%(试验1组)、0.8%(试验2组)和1.2%硫酸钠(试验3组),试验分为4期,每期18 d(预试期14 d,正试期4 d)。结果表明:(1)饲粮中添加硫酸钠后,各试验组玉米秸秆DM的瘤胃有效降解率均显著提高(P<0.05);(2)饲粮中添加硫酸钠后,各试验组玉米秸秆中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)瘤胃有效降解率均有所提高,其中试验1组和试验2组显著高于对照组(P<0.05)。结果提示,日粮中添加0.4%和0.8%的硫酸钠可以显著提高玉米秸秆DM、NDF、ADF的瘤胃有效降解率。