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.     

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.     

The effect of lasalocid on apparent digestibility, characteristics of rumen fermentation and fattening and slaughter output of bulls

Four digestion experiments with 5 wethers each (Feeding: artificially dried grass; 0, 15, 30 or 60 mg lasalocid per animal and day), two short time experiments (Exp. 1: 3 rumen fistulated sheep; feeding; artificially dried grass; 0, 15, 30 or 60 mg lasalocid per animal and day; exp. 2: 20 bulls; feeding; 2 kg concentrates per animal and day; wheat straw ad libitum; 0, 150 or 300 mg lasalocid per animal and day) and one individual feeding experiment (24 bulls per group; duration: 279 days, feeding: 2 kg concentrates per animal and day, corn silage and whole barley-grass silage ad libitum; 0 or 100/200 mg lasalocid per animal and day) were carried out in order to investigate the influence of the ionophore lasalocid on digestibility, figures of rumen fermentation as well as fattening and slaughtering results of bulls. Higher doses of lasalocid (30 and 60 mg per animal and day) decreased significantly digestibility of organic matter (1.8 and 2.8 units) and crude fibre (5.8 and 7.2 units). Relative acetate (22 to 120 mmoles per mol) and butyrate concentration (23 to 58 mmoles per mol) were decreased and molar propionate concentration of rumen liquid (25 to 154 mmoles per mol) was increased depending on level of lasalocid supplementation. Lasalocid did not significantly influence the dry matter intake; daily weight gain and slaughtering results were increased (4.4 and 6.1%), energy efficiency was improved (3.8%). Effects of lasalocid are similar to that of monensin. A dose of 20 to 30 mg lasalocid per kg dry matter is recommended.     

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。     

不同加工处理日粮对绵羊瘤胃挥发性脂肪酸的影响

选用3只健康并安装永久性瘤胃瘘管的杂种羯羊,平均体重为24 kg,采用3×3无重复拉丁方试验设计,用3种不同日粮(全混合颗粒料日粮、粉碎精料+铡短粗料日粮和未粉碎精料+铡短粗料日粮)来研究对绵羊瘤胃挥发性脂肪酸(VFA)浓度的影响。结果表明,采食未粉碎精料+铡短粗料日粮绵羊的瘤胃总挥发性脂肪酸(TVFA)浓度显著高于采食全混合颗粒料日粮绵羊(P＜0.05),采食未粉碎精料+铡短粗料及粉碎精料+铡短粗料日粮的绵羊瘤胃丙酸摩尔比显著或极显著高于采食全混合颗粒料日粮绵羊(P＜0.05,P＜0.01),而(戊酸+异戊酸)摩尔比极显著低于全混合颗粒料日粮绵羊(P＜0.01),乙酸/丙酸显著或极显著低于采食全混合颗粒料日粮绵羊(P＜0.05,P＜0.01)。因此,用粉碎精料+铡短粗料或未粉碎精料+铡短粗料日粮饲喂绵羊能改善绵羊瘤胃发酵类型。     

饲粮中燕麦干草含量对绵羊瘤胃液pH及微生物区系的影响

本试验旨在研究饲粮燕麦干草含量对绵羊瘤胃液p H及微生物区系的影响。选取9只体况和体重[(70.32±2.14)kg]相近、装有永久性瘘管的德国美利奴与蒙古羊杂种公羊,采用3×3拉丁方设计,随机分为3组,每组3只,各组分别采用全株玉米青贮、全株玉米青贮+燕麦干草(1∶1)(混合组)、燕麦干草为粗饲料。饲粮精粗比34.50∶65.50。进行3期饲养试验,每期20 d,15 d预试期,5 d采样期。采集饲喂前(0 h)和饲喂后1、3、5和7 h的瘤胃液,测定p H,采用实时定量PCR方法测定微生物相对含量。结果表明:1)全株玉米青贮组的瘤胃液p H在1、5 h均显著低于燕麦干草组(P0.05),在3 h极显著低于混合组(P0.01);2)混合组和燕麦干草组瘤胃液真菌的相对含量在0 h均极显著高于全株玉米青贮组(P0.01),燕麦干草组在5 h真菌相对含量显著高于全株玉米青贮组(P0.05);3)混合组原虫的相对含量在1、5 h显著低于全株玉米青贮组(P0.05);4)饲喂后5 h,混合组和燕麦干草组的纤维分解菌相对含量均较高,其中燕麦干草组黄色瘤胃球菌相对含量显著高于全株玉米青贮组(P0.05),白色瘤胃球菌和产琥珀酸丝状杆菌的相对含量极显著高于全株玉米青贮组(P0.01)。综上所述,在精粗比为34.50∶65.50的饲粮中采用全株玉米青贮+燕麦干草(1∶1)的粗饲料,有利于维持绵羊瘤胃内环境的稳态及瘤胃微生物的生长,白色瘤胃球菌和产琥珀酸丝状杆菌为优势菌。     

Decreasing the roughage:concentrate ratio of a diet to determine the critical roughage part for beef cattle.

The critical roughage part (CRP) of 2 diet types was determined in a cross-over design with 6 double-muscled and 6 normally conformed Belgian Blue bulls fitted with rumen cannulae. The roughage:concentrate ratio was lowered weekly until signs of a lack of physical structure were observed. For diet 1, consisting of maize silage and concentrates, the initial proportion of maize silage was 25% of DM but it decreased weekly with 5% units of DM. For the second diet, consisting of wheat straw and concentrate, 12% straw (DM basis) was provided during the first week and thereafter the proportion of straw decreased weekly with 3% units of DM. Several directly observable parameters (rumen pH, feed intake, bloat, faecal consistency) were evaluated weekly for each bull. Apart from these direct indicators of acidosis, also other parameters, whose results were only available after the end of the trial, were determined (volatile fatty acid profile, lactic acid concentration, chewing time). The roughage part between the part fed when signs of a lack of physical structure was first observed and the part that was fed the week before, was considered as the CRP. Most animals showed no acute signs of clinical acidosis (directly observable parameters) and finished the trial on a 100% concentrate diet. However, in sacco rumen DM-degradabilities of maize silage, grass silage and wheat grain was depressed considerably when low roughage diets were fed. Based on all observed parameters, the mean CRP was calculated to be 14.7% for diet 1 and 8.1% for diet 2. The beef type (double-muscled or not) had no influence on the CRP.     

Composition, digestibility and feed intake of Opuntia ficus indica by Ogaden sheep

First of all spineless Opuntia is an important source of water for livestock in tropical regions. The water content of one-year sprouts amounted to 92.5%. 70 to 75% of dry matter of Opuntia ficus indica were crude carbohydrates, approximately 20% were crude ash. The apparent digestibility of organic matter was considerably high (70.9%), the energy content amounts to 35 and 467 EFUc per kg of fresh and dry matter respectively. Opuntias are roughage, their energy content is similar to that of grass or legumes during flowering. The protein content is too low (4.5 to 5.5% crude protein of dry matter) in order to meet the protein requirements of animals. When they had the choice rams preferred chopped fresh Opuntia (61.6% of the whole DM intake) to chopped dried Opuntia (34.7%) and whole fresh Opuntia (3.7%) apart from a certain basal diet (200 g of meadow hay and 200 g of concentrate per animal and day). If only one of the three differently treated forms of Opuntia was fed (apart from the basal diet) the sheep consumed daily 359 g of dry matter of chopped fresh Opuntia (approximately the same amount as if they had the choice, 101%), 313 g of dry matter of chopped dried Opuntia (88%) and 121 g of dry matter of whole fresh sprouts of Opuntia (34% of the total intake when they had the choice.) According to the obtained results spineless Opuntia ficus indica can be used in chopped form as an additional feed to other roughages (like grass, hay, straw) especially during the dry season.     

Thiamin and niacin in the rumen

Thiamin analogs, produced in the rumen by thiaminase I, in the presence of a cosubstrate appear to be responsible for the central nervous system disorder, polioencephalomalacia (PEM). For PEM to occur, an analog must be produced that inhibits an essential thiamin-requiring reaction, and results from a cosubstrate present in the rumen. In high concentrate diets, thiaminase I is produced by rumen microbes. However, PEM can also be caused by thiaminase I of plant origin. Based on physical characteristics and cosubstrate specificity, the thiaminase I enzymes produced by Bacillus thiaminolyticus and Clostridium sporogenes appear to be different from the enzyme produced by the rumen. Because niacin and certain antihelmentics are thiaminase I cosubstrates, they should be used cautiously. Supplementary niacin increased microbial protein synthesis in vitro and in vivo, and was more effective with urea than soybean meal. Supplementary niacin (5 to 6 g X cow-1 X d-1) increased milk production in postpartum cows but not in those in mid-lactation, and in cows fed soybean meal but not in those fed urea. We believe the heating of soybean meal during commercial processing decreased the availability of niacin for rumen protozoa. Supplementary niacin for postpartum cows increased blood glucose, decreased blood ketones and reduced the incidence of ketosis. Niacin flow to the small intestine and its absorption from the small intestine increased with niacin supplementation. Supplemental niacin prevented the postpartum decrease in red blood cell niacin observed in control cows.     

Effects of pistachio by‐products in replacement of alfalfa hay on populations of rumen bacteria involved in biohydrogenation and fermentative parameters in the rumen of sheep

The objective of this study was to investigate the effect of sundried pistachio by‐products (PBP) as a replacement of alfalfa hay (AH) on blood metabolites, rumen fermentation and populations of rumen bacteria involved in biohydrogenation (BH) in Baluchi sheep. Four adult male Baluchi sheep (41 ± 1.3 kg, BW) fitted with ruminal cannulae were randomly assigned to four experimental diets in a 4 × 4 Latin square design. The dietary treatments were as follows: (i) control, (ii) 12% PBP (0.33 of AH in basal diet replaced by PBP), (iii) 24% PBP (0.66 of AH in basal diet replaced by PBP) and (iv) 36% PBP (all of AH in basal diet replaced by PBP). The basal diet was 360 g/kg dry matter (DM) alfalfa hay, 160 g/kg DM wheat straw and 480 g/kg DM concentrate. The trial consisted of four periods, each composed of 16 days adaptation and 4 days data collection including measurement of blood metabolites, rumen fermentation and population of bacteria. No differences were observed in rumen pH among the treatments, while rumen ammonia‐N concentrations were decreased (p< 0.05) with increasing PBP by up to 36% DM of the diets. Using of 36% PBP in the diet reduced (p < 0.05) total volatile fatty acids (VFA) concentrations and the molar proportion of acetate, while the concentration of propionate, butyrate and acetate to propionate ratio were similar to all other treatments. The concentration of blood urea nitrogen (BUN) decreased (p < 0.01) with increasing PBP by up to 36% DM in the diets of sheep. However, other blood metabolites were not affected by the experimental diets. It was concluded that PBP in replacement of AH had no effects on the relative abundance of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus in relation to the control diet.     

高精料诱导的SARA对泌乳期山羊血液和瘤胃液中皮质醇的影响

选择7只装有永久性瘤胃瘘管的泌乳中期山羊,2×2拉丁方设计,分别饲喂精粗比为6∶4和4∶6的饲料,通过饲喂精粗比6∶4饲料建立泌乳期山羊瘤胃亚急性酸中毒(subacute ruminal acidosis, SARA)模型,研究SARA时山羊血液和瘤胃液中皮质醇浓度、肝脏皮质醇受体(glucocorticoid receptor, GR)mRNA表达及其他相关指标的变化。结果表明,精粗比6∶4日粮饲喂2周后成功诱导SARA状态(SARA组),采食后瘤胃液pH值低于5.8持续时间约6 h,而精粗比为4∶6组山羊瘤胃液pH均高于6.0 (对照组)。高精料日粮处理对瘤胃pH和乳酸以及瘤胃液和血浆内的脂多糖、皮质醇浓度有显著性影响(P<0.05),采食前SARA组山羊瘤胃液中乳酸浓度显著高于对照组(P<0.05),采食后0~4 h乳酸含量下降,6~10 h时逐渐增加并极显著高于对照组(P<0.01);2组间瘤胃液中脂多糖浓度无显著性差异(P>0.05),SARA组血浆脂多糖浓度在采食前和采食后6 h均显著高于对照组(P<0.05);采食前SARA组山羊血液中皮质醇浓度高于对照组(P=0.05),但采食后6 h两组间无显著差异(P>0.05); 2组山羊瘤胃液中皮质醇浓度在采食后2,4和6 h分别显著高于对照组(P<0.05),但在采食前和采食后10 h无显著差异(P>0.05)。Real-time PCR结果显示,SARA组山羊肝脏中GR mRNA表达显著下调(P<0.05)。本研究结果显示,泌乳期山羊发生SARA时糖皮质激素水平升高,负反馈下调肝脏GR的表达水平,提示SARA时机体处于应激状态,可能引起肝脏的物质代谢和营养物质重分配的改变。     

瘤胃微生物体外发酵不同配比大豆荚与稻草混合粉产气量研究

为农村广泛开展稻草、玉米秸、麦秸、豆秸、谷草、荚壳等低粗饲料的有效利用,尤其是资源丰富的玉米秸秆和稻草,利用瘤胃微生物体外生物合成蛋白质饲料。试验设置7个处理组3重复,研究瘤胃微生物体外发酵大豆荚和稻草混合粉的产气量和气体种类。结果发现:大豆荚和稻草粉配比为7:3组合和6:4组合都能够促进羊瘤胃微生物体外繁殖与生长而提高饲料粗纤维的降解率。大豆荚和稻草混合粉配比7:3组合作为羊的瘤胃微生物体外发酵底物比较适宜。     

燕麦干草与全株玉米青贮不同组合对绵羊瘤胃发酵的影响

本试验旨在明确燕麦干草与全株玉米青贮按不同比例组合对绵羊瘤胃发酵的影响。选用9头体重为(70.24±2.03)kg、体况相似且装有永久性瘤胃瘘管的杂种(美利奴×蒙古羊♀)公羊作为试验动物,按过渡期称重结果分成3组,每组3只。按燕麦干草和全株玉米青贮占粗饲料比例(干物质基础)将饲粮分为A1(100%全株玉米青贮)、A2(50%全株玉米青贮+50%燕麦干草)和A3(100%燕麦干草)3种,3种饲粮精粗比均为35∶65。采用3×3拉丁方设计,进行3期试验,每期22 d(预试期15 d,正试期7 d),正试期最后3 d采样。结果显示:1)与100%全株玉米青贮相比,以50%全株玉米青贮+50%燕麦干草或100%燕麦干草为粗饲料对绵羊瘤胃液p H和总氮浓度平均值没有产生显著影响(P0.05),但显著降低了瘤胃液氨态氮(NH3-N)、尿素氮和血浆尿素氮浓度平均值(P0.05),同时以50%全株玉米青贮+50%燕麦干草为粗饲料还显著提高了瘤胃液蛋白氮浓度平均值(P0.05)。此外,A2组的瘤胃液p H和总氮浓度平均值稍高于A3组,瘤胃液蛋白氮浓度平均值较A3组增加了8.97%,瘤胃液和血浆尿素氮浓度平均值稍低于A3组,但差异均不显著(P0.05),而瘤胃液NH3-N浓度平均值则显著低于A3组(P0.05)。2)粗饲料中燕麦干草的加入并未显著改变绵羊瘤胃液总挥发性脂肪酸浓度和丙酸摩尔比平均值(P0.05),升高了瘤胃液乙酸、丁酸摩尔比以及乙酸/丙酸平均值,且A3组与A1组差异显著(P0.05)。由此可知,在精料相同、精粗比为35∶65的条件下,用50%全贮玉米青贮和50%燕麦干草混合作为粗饲料可以改善绵羊的瘤胃内环境而适宜瘤胃微生物生长,提高瘤胃微生物活性及其对氨(NH3)的利用率,有助于微生物蛋白的合成,升高瘤胃乙酸的摩尔比及乙酸/丙酸。     

全株玉米青贮饲养肉牛最佳日粮组合模式研究

对肉牛常用饲料进行营养价值评定,并选择36头6～24月龄西杂肉牛分4组分别采食不同组合日粮,试验期63～68 d.结果表明,不同饲料之间蛋白含量、有效降解率和有效能含量存在较大的差异.肉牛代谢体重干物质采食量与日粮粗蛋白含量之间存在极显著正相关关系,日增重随代谢体重采食量的增加呈直线增加,经济效益随肉牛日增重的增加而增加.以青贮 秸秆 0.5 kg肉牛浓缩料、青贮 秸秆 2 kg肉牛精料补充料、青贮 牧草 0.5 kg肉牛浓缩料、青贮 牧草 2 kg肉牛精料补充料日粮组合分别饲养西杂肉牛,日增重(ADG)分别为0.66 kg、0.90 kg、0.92 kg、1.08 kg;体况评分(BCS)分别增加0.33分、0.42分、0.56分、0.69分;日盈利分别为3.44元、4.22元、4.70元、4.41元.说明,以全株玉米青贮 优质牧草粗饲料组合饲养肉牛,再补饲含高蛋白和能促进肉牛生长及提高纤维饲料消化率的瘤胃微生物所必须矿物质的肉牛浓缩料或肉牛精料补充料,可使肉牛达到较好的增重,并获得较高的收益.     

The effect of monensin on rumen fermentation and weight gain in bulls fed a diet containing nontraditional feed

Two groups of bullocks, each consisting of 125 animals, were subjected to a trial to study the effect of monensin (Rumensin premix) administered at doses from 125 to 175 mg per head/day on rumen fermentation and weight gains. For 135 days the animals were given a diet based on green juicy forage with a supplement of chopped straw and concentrate mixture; this mixture contained 20-30% of dried poultry droppings. In the experimental group with monensin, the concentration of total and protein nitrogen and the molar percentage of propionic acid significantly increased (23.7 and 28.5%, respectively, P less than 0.01) and the acetate: propionate ratio decreased four hours after feeding. Further, the energy yield of the production by volatile fatty acids (VFA) significantly increased in the rumen contents (76.89%, 78.64%, respectively, P less than 0.05). The levels of ammonia and non-protein nitrogen were not affected by the addition of monensin. The average daily live weight gains were 713 g in the control group and 800 g in the experimental group; this means that the gains of the experimental animals rose by 12.2%. Monensin had a positive influence on the proportions of the rumen-produced VFA in favour of propionic acid which, in turn, favourably influenced the energy balance of nutrient conversion and efficiency.     

Effects of protozoa on bacterial nitrogen recycling in the rumen

The effects of protozoa on ruminal NH3-N kinetics and bacterial N recycling were measured in five sheep (57.6+/-7.1 kg BW, x +/- SD) with ruminal and duodenal cannulas in naturally faunated, defaunated, and refaunated periods. The sheep were fed a diet of 239 g of alfalfa haylage and 814 g of barley concentrate per day (DM basis) divided into 12 equal portions and allocated at 2-h intervals. A pulse dose of 300 mg of 15N as [15N]NH4Cl was administered into the rumen (on d 1 and 15) and 300 mg of 15N as [15N]urea was administered intravenously to the blood (d 8). Enrichment of 15N was measured in ruminal NH3-N, bacterial N, and plasma urea N over a period of 35 h. Total collection of urine was made for 5 d and analyzed for purine derivatives to calculate the flow of microbial N. Ruminal parameters and nutrient digestibilities were also measured. Sheep were defaunated using a rumen washing procedure 50 d prior to measurements in the defaunated period. Sheep were refaunated with ruminal contents from a faunated sheep receiving the same diet. Measurements began 26 d following refaunation, at which time protozoal numbers had returned to those in the originally faunated sheep. Data reported in parentheses are for faunated, defaunated, and refaunated sheep, respectively. Total culturable and cellulolytic bacterial numbers were unaffected by defaunation, but there was an increase in flow of microbial N from the rumen (10.8, 17.3, and 11.1 g N/d; P < .05) in the defaunated period. Flux, irreversible loss, and intraruminal recycling of NH3-N and recycling of NH3-N from plasma urea N were not affected by defaunation. Defaunation had no effect on reducing the absolute amount (13.8, 10.0, and 11.3 g N/d; P > .20) of bacterial N recycling and the percentage of N flux through the bacterial N pool. Total-tract digestion was reduced in defaunated compared with faunated sheep by 8, 17, 15, and 32% for OM, N, NDF, and ADF, respectively. In conclusion, defaunation improved ruminal N metabolism through the enhancement of bacterial protein synthesis, and improvement in the flow of microbial protein to the host animal.     

Effects of fumaric acid on rumen fermentation,milk composition and metabolic parameters in lactating cows

The aim of this study was to determine the influence of fumaric acid (FA) on ruminal fermentation and its effects on the acid‐base balance of seven ruminally and duodenally fistulated multiparous German Holstein cows. The experiment was conducted in a change‐over design with three periods in which the animals were randomly arranged in one of three treatments: Control (C; without FA), 300 or 600 g FA per day. The diets consisted of 7.4 kg DM grass silage, 4.2 kg concentrate mixture and 0, 300 or 600 g FA or wheat starch as isocaloric compensation per day and cow. FA supplementation decreased the rumen pH, acetic acid and butyric acid and increased propionic acid in rumen fluid. The results of the single‐strand conformation polymorphism analysis (SSCP) did not show an influence of FA on the microbial population in the rumen. The beta‐hydroxybutyrate (BHB) concentration in blood and the pH of the urine decreased, while the blood gases were unaffected by supplementation of the acid. The microbial protein per MJ ME decreased in the duodenum with FA supplementation. The milk fat concentration decreased after addition of FA. We conclude that in this study feeding of up to 600 g FA per day did not result in an acidosis. It seems that up to 600 g FA per day did not have a significant influence on the acid‐base balance of dairy cows.     

Alfalfa as a supplement of dried cornstalk diets: Associative effects on intake, digestibility, nitrogen metabolisation, rumen environment and hematological parameters in sheep

The aim of the current study was to investigate the associative effects of a cornstalk-based diet supplemented with alfalfa (Medicago sativa) hay on intake, digestibility, nitrogen (N) metabolisation, rumen environment and hematological parameters in Xiaoweihan sheep. We also investigated the optimal range of alfalfa hay to achieve positive associative effects and avoid negative effects. Xiaoweihan sheep (n = 5; fitted with rumen T-cannula) were fed five cornstalk-based diets in a 5 × 5 Latin square design. Diets contained 0, 50, 150, 300, 450 g alfalfa, and were supplemented with 100 g concentrate, respectively. Our results suggested that supplementation of 300 g alfalfa hay reduced (P < 0.05) cornstalk intake, but significantly increased dry matter (DM) intake (P < 0.05). Additionally, DM digestibility of 150 g alfalfa hay supplementation was slightly higher than that noted in other diets. Metabolism studies showed 50–150 g alfalfa hay supplementation had a positive associative effect (P < 0.05) on N utilization, with the greatest benefit noted with 150 g per day (P < 0.05) compared to unsupplemented diets. Alfalfa supplementation (50–450 g per day) resulted in an elevated trend of ammonia nitrogen (NH₃–N) with 50 or 150 g of alfalfa hay more likely to promote sheep rumen environment, with a noticeable increase (P < 0.05) in serum urea nitrogen (UREAN) concentrations observed with 300 g alfalfa hay per day. Our data suggested that the optimal range to achieve beneficial effects and avoid negative effects was 150–300 g per day for cornstalk-based diets for sheep.     

绵羊日粮的阳离子交换量与其纤维物质在胃肠道中的消化动力学的关系研究

采用12头安装有瘤胃和十二指肠瘘管的绵羊作为试验动物，随机分成4组，研究以稻秆(RS)、小麦秸(WS)、玉米秸(MS)和花生藤(PV)4种不同的阳离子交换量(CEC值)为主的绵羊日粮对纤维物质消化动力学、瘤胃降解率和瘤胃内环境参数的影响。结果表明：不同日粮的CEC值不同，具有较高CEC值的日粮(如玉米秸和花生藤)，营养价值也较高，其营养物质在十二指肠和直肠的流通量要比CEC值低的日粮(稻秆和麦秸)小，但具有较高的消化率，其粗纤维物质具有较多的可消化营养物质(a b)和较高的表面可发酵指数(SAFI)以及较高的瘤胃降解率。同时，随着日粮CEC值升高，各种营养物质在十二指肠和直肠中的流通量呈下降的趋势，各种营养物质在绵羊消化道中各部位的消化率呈上升的趋势，而且各营养物质的瘤胃降解率也有逐步升高的趋势。