Influence of dietary niacin on volatile fatty acids in rumen liquid of sheep and rumen dry matter degradability of untreated and ammonia-treated wheat straw

Three rumen fistulated sheep were fed with roughage (1200 g artificially dried grass) or a concentrate/roughage diet (600 g concentrate, 400 g artificially dried grass per animal and day). The diets were unsupplemented or 0.5, 1 and 2 g niacin per animal and day were added. After a 14-day adaptation period samples of rumen liquid were taken 0, 1, 2, 3, 4 and 6 h after morning feeding. In a second experiment untreated and NH3-treated wheat straw were incubated in nylon bags for 6, 12, 24, 48 and 72 h in the rumen of 5 sheep fed with 1.2 kg artificially dried grass and unsupplemented or supplemented with 1 g niacin per day. Niacin did not significantly influence the total concentration of volatile fatty acids, acetate and branched chain fatty acids in both types of diet (P less than 0.05). 0.5 and 1 g niacin in the roughage and 0.5 g niacin in concentrate/roughage diet increased the propionic acid concentration and reduced the butyric acid concentration in rumen liquid of sheep (P less than 0.05). Niacin resulted in a small decrease (P greater than 0.05) of dry matter degradability in rumen. After 48 h incubation time, the dry matter disappearance of untreated and NH3-treated wheat straw amounted to 35.4 and 46.2% resp. The effects of niacin on rumen fermentation may be useful in avoiding ketogenic situations in dairy cows.     

棉粕与豆粕在反刍动物瘤胃内降解动力学的评定分析

本试验旨在评定棉粕与豆粕的干物质（DM）、有机物（OM）、粗蛋白质（CP）在绵羊瘤胃内的降解动力学参数变化及瘤胃降解前后有效赖氨酸的含量变化。选用3只安装有永久性瘤胃瘘管的体重为（28.0±2.97）kg的育肥哈萨克公羊,代谢笼内单笼饲喂,每天饲喂棉籽壳200 g、精料500 g、小麦秸500 g,余料不超过10%。采用尼龙袋技术评定棉粕与豆粕DM、OM及CP的降解动力学参数,计算有效降解率（ED）及瘤胃停留时间（RRT）,染料结合法（DBL）测定有效赖氨酸的含量。结果表明,在瘤胃固相食糜的平均外流速度为1.84%/h条件下,豆粕DM、OM及CP的瘤胃降解率及有效降解率均高于棉粕,而瘤胃停留时间均短于棉粕。豆粕经瘤胃内培养16 h后有效赖氨酸含量略有升高,而棉粕无明显变化。该试验结果为进一步评定棉粕及豆粕养分的小肠消化率提供参考。     

瘤胃厌氧真菌对木质素含量不同底物附着及发酵特性研究

结合体外发酵和瘤胃尼龙袋法,研究了本地山羊瘤胃厌氧真菌对木质素含量不同底物(黑麦草叶、黑麦草茎、稻草秸、花生壳,木质素含量依次上升)的附着及发酵特性.结果表明,随体外发酵的进行,真菌数量逐渐增加,以黑麦草叶、黑麦草茎、稻草秸为底物时,瘤胃真菌数量均在48 h达到最大值,且真菌数量的最大值随底物木质素含量的上升呈下降趋势.显微观察显示,体外发酵前72 h附着于稻草秸表面孢子囊数量均显著高于黑麦草叶和黑麦草茎(P<0.05),而切缘孢子囊数量三者差异不显著.瘤胃内培养结果表明,稻草秸切缘和表面孢子囊数量均在48 h时最大,72 h后数量显著下降(P<0.05),而黑麦草茎切缘和表面上的孢子囊数量均在24 h 时最大,72 h后数量显著下降(P<0.05);稻草秸切缘和表面上孢子囊数量均要高于黑麦草茎上的数量.不同底物进行厌氧真菌体外发酵时其累计产气量、干物质消失率和纤维素消失率差异均不显著,但在瘤胃内培养时,各底物的干物质消失率则随底物木质素含量的上升而显著下降(P<0.05).     

Ruminal phytate degradation of maize grain and rapeseed meal in vitro and as affected by phytate content in donor animal diets and inorganic phosphorus in the buffer

The ruminal disappearance of phytate phosphorus (InsP₆‐P) from maize grain and rapeseed meal (RSM) was determined in two in vitro studies. In experiment 1, two diets differing in phosphorus (P) and InsP₆‐P concentration were fed to the donor animals of rumen fluid (diet HP: 0.49% P in dry matter, diet LP: 0.29% P). Maize grain and RSM were incubated in a rumen fluid/saliva mixture for 3, 6, 12 and 24 h. In experiment 2, a diet similar to diet HP was fed, and the rumen fluid was mixed with artificial saliva containing 120 mg inorganic P/l (Pi) or no inorganic P (P0). Maize grain and RSM were incubated with either buffer for 3, 6, 12 and 24 h. Total P (tP) and InsP₆ concentration were analysed in the fermenter fluids and feed residues. The disappearance of InsP₆‐P from maize was completed after 12 h of incubation in both experiments. From RSM, 93% (diet LP) and 99% (diet HP) of the InsP₆‐P in experiment 1 and 80% (Pi) and 89% (P0) in experiment 2 had disappeared after 24 h of incubation. InsP₆‐P disappearance was higher when diet HP was fed (maize: 3 and 6 h; RSM: 6 and 24 h of incubation) and when rumen fluid was mixed with buffer P0 (maize: 6 h; RSM: 12 and 24 h of incubation). InsP₆‐P concentration in the fermenter fluids was higher for maize, but no accumulation of InsP₆‐P occurred, indicating a prompt degradation of soluble InsP₆. These results confirmed the capability of rumen micro‐organisms to efficiently degrade InsP₆. However, differences between the feedstuffs and diet composition as well as the presence of inorganic P in the in vitro system influenced the degradation process. Further studies are required to understand how these factors affect InsP₆ degradation and their respective relevance in vivo.     

Profile of isoacids in rumen fluid and influence of added isoacids on in sacco dry matter disappearance of untreated and ammonia treated wheat straw

The influence of type of diet and time after feeding on concentration of isoacids in rumen fluid of 6 fistulated sheep were investigated. The concentration of isoacids in rumen fluid was higher in diets rich in concentrate and protein (5.6) than in roughage diets (3.4) or in straw-starch-urea diets poor in native protein (highest concentration: 2.1 mmol/l rumen fluid). Feeding of roughage diet or straw-starch-urea-diet effected a significant decrease of concentration of isoacids in the rumen fluid after morning feeding, but concentrate-roughage diet, increased the isoacids-concentration. Reasons for decreased concentration of isoacids may be a shortage of corresponding amino acids and a high activity of cellulolytic microbes. Infusion of isoacids (3 g per day) in the rumen of sheep fed with a straw-starch-sugar-urea diet did not significantly influence the in sacco dry matter degradability of untreated wheat straw, but increased the dry matter loss of ammonia treated wheat straw from 16.0; 26.6; 39.4; 54.0 and 58.8% to 17.3; 29.7; 43.1; 56.3 and 63.0% after 6; 12; 24; 48 and 72 h rumen incubation time respectively. Further experiments seem to be necessary. The effect of isoacids may be expected to occur with poor quality feeds, rich in fibre low in protein and hence low in branched-chain amino acids.     

Effect of exogenous xylanase on rumen in vitro gas production and degradability of wheat straw

The objective of this study was to determine effects of xylanase on in vitro gas production (GP) and in sacco degradability of wheat straw. Rumen fluid was obtained from three Mongolian native goats fitted with permanent rumen cannulas. The trial consisted of five doses (0, 0.5, 1.0, 1.5, 2.0 μL/g of substrate) of a commercial xylanase (Dyadic^® xylanase PLUS, Dyadic International, Inc., Jupiter, FL, USA). For the in sacco degradability, different levels of xylanase enzyme were added directly onto 2 g of wheat straw in nylon bags and incubated in the rumen for 3, 6, 12, 24 and 48 h to estimate degradability of wheat straw. Total GP increased (P < 0.001) at all times of incubation at intermediate levels of xylanase. Methane production had a similar pattern at 3 and 12 h of incubation; increased linearly at 24 h of incubation, and was unaffected at 6 and 48 h of incubation. Rumen NH₃‐N concentration increased linearly at 3 h and the highest values were observed with intermediate enzyme levels. All ruminal volatile fatty acids increased linearly with intermediate levels of the fibrolytic enzyme. The in sacco rate of dry matter degradation decreased linearly (P = 0.020) with increasing enzymes. Intermediate levels of xylanase improved rumen kinetic fermentation and degradability. The outcome of this research indicated that the application of xylanase enzyme could improve in vitro GP fermentation of wheat straw.     

Effect of dietary choline on volatile fatty acids in rumen liquid of sheep and rumen dry matter degradability of untreated and ammonia-treated wheat straw

Three rumen fistulated wethers consumed a roughage (1200 g artificially dried grass) or a concentrate/roughage diet (600 g concentrate, 400 g dried grass per animal and day). The diets were unsupplemented or 0.5, 1 or 2 g choline per animal and day were added. After a 14-day feeding period, samples of rumen liquid were taken 0, 1, 2, 3, 4 and 6 h after morning feeding. In a second experiment, untreated and ammonia-treated wheat straw were incubated in nylon bags for 6, 12, 24, 48 and 72 h in rumen of 5 sheep fed on 1.2 kg dried grass and without or with 1 g choline per day. Choline supplementation decreased the total concentration of volatile fatty acids in rumen liquid in both types of diet (roughage: 106, 83, 89 and 87; concentrate/roughage: 142, 114, 91 and 106 mmol/l for 0, 0.5, 1 and 2 g choline per day resp.). Concentration of acetate and branched chain fatty acids in both diets and butyrate in concentrate/roughage diet was reduced as total acids. Butyrate in roughage diet was increased by added choline. Molar propionate concentration was not significantly influenced by choline (P greater than 0.05). Choline resulted in a little increase (P greater than 0.05) of dry matter degradability in rumen, especially when NH3-treated straw was incubated. The effect of choline on milk fat production of cows fed with diets rich in concentrate is probably not related to changes in rumen fermentation and digestion.     

Influence of yeast (Saccharomyces cerevisiae as Yea-Sacc or Levaferm) on in Sacco dry matter degradability and ruminal parameters of variously fed small ruminants.

Two series of experiments with rumen fistulated castrated male sheep and goats were carried out. In experiment I three sheep each consumed rations rich in concentrate (700 g concentrate, 200 g chopped wheat straw) or roughage (700 g artificially dried ryegrass, 200 g chopped wheat straw per animal per day) and supplemented with 0, 1, 2 or 4 g Yea-Sacc (Saccharomyces cerevisiae; USA) per sheep per day. In experiment II three sheep were fed with 1000 g artificially dried ryegrass and 200 g concentrate, three goats consumed 750 g ryegrass and 150 g concentrate. 0, 0.5, 1 or 2 g Levaferm (Saccharomyces cerevisiae; Germany) per animal per day were added. Rations of all animals were supplemented with minerals and vitamins. After 14 days of feeding wheat straw, ammonia treated wheat straw and artificially dried grass (exp. I) or wheat straw and artificially dried grass (exp. II) were incubated in nylon bags in the rumen for 6, 12, 24, 48 and 72 hours. At the end of the experiments rumen fluid was taken via cannulae and parameters of rumen fermentation were measured. Higher levels of added Yea-Sacc decreased in sacco dry matter degradability of all incubated feeds. Depression was much higher if Yea-Sacc was added to the concentrate ration (overall mean for 24, 48 and 72 h incubation time: 55.1, 47.1, 46.1 and 44.5 for 0, 1, 2 and 4 g Yea-Sacc) than to the roughage diet (58.7, 56.3, 55.0 and 54.1%). Levaferm did not significantly influence the rumen dry matter degradability of incubated feeds (overall mean for 24, 48, and 72 h incubation time: 64.0; 64.9; 64.9 and 64.2% for sheep; 63.0; 63.2; 63.2 and 61.6% for goats, if added with 0, 0.5, 1 and 2 g Levaferm per animal per day). Rumen pH, concentration of volatile fatty acids and molar concentration of fatty acids in rumen fluid were not significantly influenced by added yeasts. More research seems necessary to find out the mode of action of yeast and to quantify and to reproduce the effects of added yeast.     

尼龙袋法和改良体外三步法评定瘤胃保护性赖氨酸的瘤胃降解率及小肠消化率

本试验旨在利用尼龙袋法和改良体外三步法评定脂肪粉包被赖氨酸（Lys）的瘤胃降解率及小肠消化率。选用3只安装有永久性瘤胃瘘管的体重为（28.0±2.97）kg的5月龄哈萨克公羊,代谢笼内单笼饲养,每天饲喂棉籽壳200 g、精料500 g、小麦秸400～500 g,余料不超过10%。结果表明,该脂肪粉包被赖氨酸的干物质（DM）及粗蛋白质（CP）在瘤胃内的有效降解率均为20%,瘤胃保护率达到80%。经胃蛋白酶和胰酶培养24 h后,DM及CP的消化率分别达到63.6%和98.8%。综上所述,该脂肪粉包被赖氨酸可作为一种新型有效的反刍动物氨基酸补充形式。     

The ruminal nitrogen metabolism in calves and sheep. 2. Studies in wethers

Energetically differing rations which received ca. 45% of their crude protein from a supplement of soybean oil meal or urea were tested in a model experiment with adult wethers fitted with duodenal re-entrant cannulae or rumen cannulae resp. The N-equivalent exchange of soybean oil meal by urea in wethers resulted in a distinct increase of the NH3-N content of the rumen fluid, an increase of irreversible N losses and thus a worsening of the utilization of the available N for bacterial N-efficiency. A significant influence on duodenal NAN passage, on the apparent fermentation of the organic matter, on postruminal NAN digestibility and on the content of amino acid nitrogen as well as the amino acid composition of the duodenal NAN could not be detected. The increase of the energy level of the rations did not have a significant influence on the parameters of the ruminal N metabolism in the wethers. The studies with calves and adult wethers showed that a transposition of the parameters of ruminal N metabolism obtained to calves is not possible under the conditions given.     

小麦秸秆处理方式对绵羊生长性能、瘤胃发酵性能及经济效益的影响

文章旨在评估不同小麦秸秆处理方式对干物质体外降解动力学及绵羊生长性能和瘤胃发酵性能的影响。试验将平均初始体重为（51.26±0.07）kg的24头绵羊随机分为3组,每组4个重复,每个重复2头羊。3组绵羊每天采食体重1%的基础浓缩料,对照组自由采食未处理的小麦秸秆,处理组绵羊分别采食2.5%氨水处理的小麦秸秆和5×108 CFU酵母菌处理的小麦秸秆,试验共进行10周。结果：氨化秸秆与酵母处理秸秆组干物质体外降解动力学参数B较小麦秸秆组分别显著提高11.04%和13.63%（P＜0.05）,而氨化秸秆组干物质体外降解动力学参数A+B较小麦秸秆组显著提高11.45%（P＜0.05）。氨化秸秆组干物质降解效率显著高于未处理的小麦秸秆组（P＜0.05）。与小麦秸秆组相比,氨化秸秆和酵母秸秆组绵羊的平均日增重分别显著提高9.12%和13.11%（P＜0.05）。氨化小麦秸秆组绵羊的能量和蛋白质摄入量最高（P＜0.05）。氨化小麦秸秆组绵羊瘤胃发酵0～8 h的氨氮浓度均最高（P＜0.05）,而酵母秸秆组绵羊瘤胃液体外发酵2 h后的挥发性脂肪酸浓度较小麦秸秆组显著提高32.84%（P＜0.05）,体外发酵4 h后的挥发性脂肪酸浓度显著高于其他两组（P＜0.05）。结论：氨水和酵母菌处理提高小麦秸秆的水不溶性物质（B组分）降解率和绵羊的平均日增重,同时氨水处理小麦秸秆提高了绵羊代谢能、蛋白质摄入量和瘤胃氨氮浓度。     

Nitrogen metabolism in the large intestine of ruminants. 6. Metabolism of intracecally administered 14C and 15N urea in sheep with simultaneous intracecal doses of heat-damaged hay

Two wethers (28 kg and 33 kg) were supplied with ileocaecal re-entrance cannulae and received a straw pellet ration rich in crude fibre (70.5% straw, 12% chopped sugar beet, 10% cereals, 2% urea, 3% NH4HCO3 and 2.5% of a mineral mixture). In a preliminary period 50% of the digesta flow was collected on 6 successive days for 18 h each. An amount of digesta sufficient for 24 h was apportioned for hourly application and stored at a temperature of -20 degrees C for the main trial. In the main trial the two animals received intracaecally the collected digesta with a supplement of ca. 6 g hay damaged by heat/kg LW(0.75) in hourly portions over 24 h (hay made up ca. 15 and 20% resp. of the DM amount). In addition, each digesta sample was supplemented with 14C and 15N labelled urea (19.7.10(6) Bq 14C urea and 364 mg 15N excess from 15N urea). About 9% of the applied 15N amount was microbially utilized; the utilization quota was thus lower than after the application of partly hydrolyzed straw meal (16% in a previous trial). The 14C activity from 14C urea was quickly eliminated in the form of CO2 in the respiratory gases (at the 18th hour after the end of the infusion 70% excreted as CO2). The half-lives for the urea resulting from the semi-logarithmic decrease of the atom-% 15N excess in the blood plasma were 7.9 and 7.7 resp. 23% and 34% resp. of the applied 15N excess were excreted in urine. The excretion of radioactive carbon in urine, however, was at 2.8% and 4.3% resp. of the applied amount very low 120 h after the beginning of the trial (96 h after the end of the infusion). On the whole one can conclude from this trial that hay damaged by heat has only a low stimulating effect on microbial activity in the large intestine.     

The nitrogen metabolism in the large intestine of ruminants. 8. Metabolism of intracecally infused 15N-urea with a supplement of pectin in heifers]

Three heifers with live weights of 255, 261 and 300 kg were supplied with ileo-caecal re-entrant cannulas, jugular vena catheters and bladder catheters. The ration consisted of 4 kg maize silage and 4 kg wheat straw pellets. In a previous period 50% of the digesta flow was collected over 12 h/d on 5 consecutive days and stored in a deep-freeze. During the main period the re-entrant cannulas were disrupted and the flowing digesta was quantitatively collected. Precollected digesta and pectin were infused into the distal part of cannula hourly for about 30 hours. During the first 24 hours the digesta was also supplemented with 15N-labelled urea. The amount of pectin corresponded to about 10% of digesta dry mater. An analysis of urine, faeces, digesta and blood plasma were carried out. The application of pectin increased the 15N-incorporation in the bacterial protein of faeces from 4.7% (without supplementation in an earlier experiment) to 10.5% of the introduced 15N. The ammonia-fraction of faeces was markedly higher than the bacterial fraction. The 15N-utilization of urea by the microbes of large intestine was lower in the actual trial evident than with supplementation of starch in the anterior experiment. During the pectin administration the amount of urine increased in comparison with earlier experiments and according to the literature to about the 4.5 fold. The amount of passage of 15N at the ileum cannula (recycled 15N) was 3.8% of the 15N intake. It is the same amount as in experiments in which starch was applied.     

The effect of a straw meal on the crude protein and amino acid metabolism and digestibility of the crude nutrients in broiler hen breeds. 2. Digestibility of crude nutrients of rations and 15N from a straw meal and wheat

In experiments with colostomized broiler hens apparent digestibility of the crude nutrients of the ration after straw meal supplements of 20, 30 and 40 g per animal was determined. In addition, the 15N digestibility of straw meal and wheat was ascertained on the basis of straw meal supplements. The digestibility of the crude nutrients of the rations decreased significantly (P less than 0.05) after the straw meal supplement. The adaptation of the test animals to the straw meal intake resulted, at a daily consumption of 20 g straw meal, in an increase of the apparent crude fat digestibility (P less than 0.05) in dependence on the time of straw meal feeding, in which the original values without straw meal supplement were not reached. The digestibility of the 15N excess (15N') of the wheat was, at 86 +/- 1%, largely independent of the straw meal intake. The apparent digestibility of the straw-15N excess in broiler hens of 42 +/- 8 to 55 +/- 2% is surprisingly high.     

青贮对薯渣干物质和淀粉瘤胃降解规律的影响

选择4头装有永久性瘤胃瘘管的荷斯坦奶牛作为试验动物,利用尼龙袋法研究了马铃薯渣和红薯渣青贮前后干物质和淀粉瘤胃降解规律。结果表明,青贮后马铃薯渣和红薯渣的干物质和淀粉的瘤胃72 h消失率及有效降解率均极显著降低（P＜0.01）,马铃薯渣干物质和淀粉消失率由青贮前的95.72%和99.60%下降为53.43%和86.51%,红薯渣则由97.65%和99.81%下降为66.72%和84.69%,马铃薯渣干物质和淀粉的有效降解率降低了47.34%和35.98%,红薯渣则下降了51.48%和57.39%;马铃薯渣青贮和红薯渣青贮干物质的有效降解率差异不显著（P＞0.05）,淀粉差异显著（P＜0.05）;马铃薯渣和红薯渣青贮后过瘤胃淀粉分别增加了57.43%（42.94 g/kg）和151.37%（122.52 g/kg）,且红薯渣极显著高于马铃薯渣（P＜0.01）。因此,青贮处理有效降低了2种薯渣干物质和淀粉的瘤胃降解率,并提高了其过瘤胃淀粉量,红薯渣的过瘤胃淀粉量明显高于马铃薯渣。     

Effects of potassium on macromineral absorption in sheep fed wheat straw-based diets

Two experiments were conducted to determine the effect of increasing dietary K on macromineral bioavailability from a wheat straw-hay diet, and to monitor changes in the rumen that could affect mineral availability. In the first experiment, 12 mature wethers were used in a metabolism study to determine the effect of adding potassium chloride (KCl) to a supplement fed with a diet of 55% NH3-treated wheat straw and 45% bromegrass hay. In the second experiment, similar diets were fed to six wethers with ruminal and abomasal cannulae to determine the site of mineral absorption. Dietary K levels were 1, 2 and 3% of the diet dry matter. Increasing K tended to decrease (P less than .06) apparent absorption of Mg. Potassium absorption increased (P less than .01) with increasing dietary K, but retention was not altered. Quadratic effects (P less than .01) of K were observed for Ca and P apparent absorption and retention. Increased K lowered (P less than .05) plasma Mg in Exp. 1 but not in Exp. 2. Ruminal concentrations of K increased (P less than .01), and concentrations of Na decreased (P less than .05), as dietary K increased. Ruminal fermentation was influenced by dietary K level. Molar proportions of acetate in the rumen were increased (P less than .01) by the addition of K to the diet, while molar proportions of butyrate (P less than .01) and valerate (P less than .01) decreased linearly with increasing K. Time X treatment interactions were present for ruminal propionate, butyrate and NH3-N (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of replacing dietary starch with neutral detergent–soluble fibre on ruminal fermentation,microbial synthesis and populations of ruminal cellulolytic bacteria using the rumen simulation technique (RUSITEC)

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.     

The effect of pelleting on in situ rumen degradability of compound feed containing brown rice for dairy cows

This study was conducted to determine the effect of pelleting on in situ dry matter degradability of pelleted compound feed containing brown rice for dairy cows. Mash feed of the same composition was used as a control and the in situ study was conducted using three non‐lactating Holstein steers fitted with a rumen cannula. The feeds contained 32.3% brown rice, 19.4% rapeseed meal, 11.4% wheat bran and 10.6% soybean meal (fresh weight basis). Except for moisture content, the chemical composition of the feed was not affected by pelleting. In situ dry matter disappearance of the feed increased from 0 to 2 h and after 72 h of incubation with pellet processing. Integration of the dry matter disappearance values over time revealed that degradability parameter a (soluble fraction) increased with pellet processing, whereas parameter b (potentially degradable fraction) decreased. Parameter c (fractional rate of degradation) and effective degradability (5% passage rate) were not affected by pellet processing. We concluded that pellet processing promotes rumen degradability at early incubation hours when the pelleted feed contains brown rice.     

体外驱除瘤胃厌氧真菌对绵羊和山羊细菌、原虫及稻草干物质降解率的影响

选择体况良好、体重30kg左右、安装有永久性瘤胃瘘管的内蒙古白绒山羊和内蒙古土种去势绵羊各3只作为供体羊,为体外批次培养提供瘤胃液。比较研究了驱除瘤胃厌氧真菌对绵羊和山羊细菌、原虫及稻草干物质降解率的影响。结果表明:对照组(F0组)绵羊瘤胃液中真菌游动孢子数量多于对照组山羊瘤胃液;且在培养的2、4、6、48、72小时差异显著(P<0.05)。在培养初期(0～12小时)山羊F0组和F2组(驱真菌组)细菌总数均高于绵羊;绵羊和山羊驱真菌组(F2组)细菌总数均高于对照组(F0组)。山羊F0组(对照组)原虫数量各时间点的平均数显著高于绵羊F0组(P<0.05)。驱除厌氧真菌后绵羊和山羊对稻草干物质降解率显著下降,分别下降了12.06%和8.62%。这说明瘤胃厌氧真菌在纤维物质降解过程中的确发挥了重要作用。     

Absorption and utilization of amino acids infused into the cecum of growing pigs. 2. 15N-labeled lysine

Over a period of 4 days 15N-labelled lysine was infused into two growing female pigs (live weight approximately 50 kg) through a caecal cannula. The feeding was restrictive (1,400 g dry matter/day) and, with regard to lysine, it didn't meet the requirement. In a 7-day experiment the N- and 15N-content was measured periodically in the excretions (feces and urine), in various fractions of the blood and in selected slaughtering samples. From the infused 15N 3-5% are excreted as lysine in feces, another 5% are in other amino acids of the bacteria protein. The disappearance rate of 15N' from the large intestine makes greater than or equal to 90%. The biggest part of this 15N (78-88%) is excreted with the urine in form of 15N-urea. Obviously the infused amino acid is decomposed to NH3 in the large intestine and then absorbed. The absorbed ammonia is changed into urea in the ornithine cycle and excreted in urine. The recovery rate of the 15N infused as 15N-lysine is 93 and 84% resp. Incorporation of 15N in to serum protein or other body protein could not be detected so that the remaining difference of 7-16% cannot necessarily be interpreted as incorporation rate of 15N into the body protein. Under practical conditions the maximal utilisation of lysine from the feed in the large intestine is 1.6% and should thus be without importance.