不同种类精饲料中磷的瘤胃降解特性研究

测定了谷物籽实、豆类籽实及根茎三类共计15种饲料的磷含量,并应用尼龙袋法测定其在山羊瘤胃内的降解率。结果表明：三类饲料的磷含量存在明显差异,以豆类籽实最高,谷物籽实其次,根茎类最低。饲料种类间磷的瘤胃降解率差异极显著（P〈0.001）,谷物类、豆类和根茎类饲料中快速降解磷（A）分别以玉米（88.82%）、豌豆（92.66%）和红薯（94.69%）最高,而以大米、赤豆和木薯为最低。除大麦、大米和小米外,其他饲料的快速降解磷均在60%以上。除小麦外,慢速降解的磷（B）都低于40%。磷在瘤胃中的降解速率（C）都超过10%/h以上,仅大米、小米和土豆的慢速降解部分的降解速率低于10%/h。不同种类精饲料总的可降解磷（A＋B）都在80%以上。不同种类饲料磷的有效降解率都随外流速率的增大而下降,除大米和小米外,其他饲料磷的有效降解率都超过了80%。饲料中磷的含量与磷的有效降解率呈显著正相关关系,磷的降解速率与粗脂肪含量呈极显著正相关关系,淀粉含量则与磷的有效降解率呈显著负相关关系,磷的含量与粗蛋白含量间呈极显著正相关关系。上述结果显示,饲料中磷在瘤胃中绝大部分都可释放出来,故配制反刍动物日粮时必须考虑饲料原料中磷的含量及其有效降解率。     

蛋白质和过瘤胃脂肪对晋南牛瘤胃发酵和尿嘌呤衍生物的影响

为探究蛋白质和富含不饱和脂肪酸的过瘤胃脂肪对瘤胃发酵和尿嘌呤衍生物的影响,选用4头装有永久性瘤胃瘘管的晋南阉牛,按照蛋白质需要量的85%、100%和115%设计3个水平,并在此基础上添加0、2.5%、5.0%和7.5%的亚麻油制作的钙皂作为过瘤胃脂肪,采用3×4两因素设计,共形成12组饲粮组合,测定瘤胃pH、氨态氮浓度(NH_3-N)浓度、挥发性脂肪酸(VFA)含量以及尿嘌呤衍生物(PD)的排出量。结果表明,蛋白质和过瘤胃脂肪水平对瘤胃pH均无显著影响。蛋白质水平对NH_3-N浓度影响显著,9组NH_3-N显著高于1、2、3、4和8组,10组显著高于3和8组;对丙酸和乙酸、丁酸、乙酸/丙酸及总酸分别具有极显著和显著影响,5组的乙酸浓度较1、2、3和4组显著提高,9、10和11组瘤胃液中的丙酸浓度较1和2组显著提高,12组较2组显著提高,10组的丁酸浓度显著高于7和8组,1和2组的乙酸/丙酸比值显著高于9、10和11组;对精补料养分有效降解率影响极显著,对秸秆有机物(OM)和酸性洗涤纤维(ADF)分别具有极显著和显著影响,10组精补料粗蛋白质(CP)瘤胃有效降解率显著高于2、3、4、5、6、7和8组,1、9、11和12组显著高于4、5、6、7和8组;对玉米秸秆中ADF瘤胃有效降解率6、7和8组显著高于除5和12组之外的其余各组,5和12组显著高于除9和11组之外的其余各组;对尿囊素和尿嘌呤衍生物有显著影响,12组的尿囊素和尿嘌呤衍生物显著高于1和4组,11组尿酸显著高于其余组。综上,饲粮蛋白质水平对瘤胃发酵和尿嘌呤衍生物具有显著影响,饲粮蛋白质水平为饲养标准需要量前提下,过瘤胃脂肪适宜添加量为饲粮的5%。本研究结果为肉牛养殖中日粮过瘤胃脂肪添加量及蛋白质水平提供了一定的依据。     

Beef authentication and retrospective dietary verification using stable isotope ratio analysis of bovine muscle and tail hair

Stable isotope ratio analysis (SIRA) was used as an analytical tool to verify the preslaughter diet of beef cattle. Muscle and tail hair samples were collected from animals fed either pasture (P), a barley-based concentrate (C), silage followed by pasture (SiP), or silage followed by pasture with concentrate (SiPC) for 1 year (n = 25 animals per treatment). The (13)C/(12)C, (15)N/(14)N, (2)H/(1)H, and (34)S/(32)S isotope ratios in muscle clearly reflected those of the diets consumed by the animals. By applying a stepwise canonical discriminant analysis, a good discrimination of bovine meat according to dietary regimen was obtained. On the basis of the classification success rate, the (13)C/(12)C and (34)S/(32)S ratios in muscle were the best indicators for authentication of beef from animals consuming the different diets. Analysis of (13)C/(12)C and (15)N/(14)N in tail hair sections provided an archival record of changes to the diet of the cattle for periods of over 1 year preslaughter.     

花生壳和麦秸用于饲养肉牛的营养价值和化学处理

为了评定花生壳、麦秸和花生壳-麦秸型典型肉牛日粮的营养价值，分析了粗饲料和日粮的营养成分，以3只瘤胃瘘管山羊和尼龙袋技术评价了粗饲料和日粮中干物质和粗蛋白质的瘤胃降解率，以5头肉牛进行了日粮消化率测定；对花生壳和麦秸分别进行氨化处理和综合化学处理，以不同组的肉牛进行60 d的饲养试验，比较氨化处理以及综合化学处理对粗饲料饲养效果的影响。结果表明，花生壳中粗纤维含量高于麦秸，花生壳和麦秸中粗蛋白质含量低、干物质降解率高而粗蛋白质降解率低；以花生壳和麦秸为主要成分的典型肉牛日粮，干物质和粗蛋白质的降解率高且稳定，其干物质、粗蛋白质和粗纤维的消化率分别为44.60%, 61.88% 和30.41%。以3.5%的尿素氨化处理花生壳及麦秸对肉牛具有良好的饲养育肥效果；对花生壳以3.5%的尿素和4%的Ca(OH)₂进行综合化学处理，其效果优于单纯的氨化处理。     

Utilizing Composted Beef Cattle Manure and Slaughterhouse Waste as Nitrogen and Phosphorus Fertilizers for Calcareous Soil

Effectively utilizing composts requires that their nitrogen (N) and phosphorus (P) contents be used as fertilizer, but how this is best accomplished is not fully understood. The authors' objective was to quantify N and P availability of a calcareous clay loam soil receiving composts derived from four contrasting beef cattle feedlot feedstocks applied at 50, 150, and 450 mg total P kg^?1 and supplemented twice with fertilizer N for a 42-week greenhouse plant bioassay. Three composted manures from beef cattle fed distinct diets and a composted mix of slaughterhouse and construction waste were applied. Inorganically fertilized and non-amended soils were included as controls. Canola (Brassica napus L.) and pea (Pisum sativum L.) were grown in pots containing 1.5 kg air-dried soil for six alternating 7-week cycles. Soils amended with composted manure from beef cattle fed typical finishing diets had the lowest apparent N recovery (31%) and the greatest soil nitrate after 42 weeks (25 mg N kg^?1). Phosphorus availability was greater with composted manure from beef cattle fed distillers' dried grains than composted manure from beef cattle fed typical finishing diets and a composted mixture of slaughterhouse and construction waste. Apparent P recovery (66%) was greatest from composted manure of beef cattle fed corn (Zea mays L.) distillers' dried grains applied at 50 mg total P kg^?1. Composted manure from beef cattle fed distillers' dried grains had greater P availability than conventional composted beef cattle feedlot manure. Overall, performance of the composted mixture of slaughterhouse and construction waste was similar to the composted beef cattle manures.     

Enzymic degradability of hull-less barley flour alkali-solubilized arabinoxylan fractions by endoxylanases

The impacts of the arabinose to xylose (A/X) ratio of arabinoxylans (AX) and the endoxylanase substrate specificity on the enzymic degradability of hull-less barley flour AX by endoxylanases were studied by using alkali-solubilized AX (AS-AX) fractions with different A/X ratio, on the one hand, and glycoside hydrolase family 10 and 11 endoxylanases of Aspergillus aculeatus (XAA) and Bacillus subtilis (XBS), respectively, on the other hand. AS-AX were obtained by saturated barium hydroxide treatment of hull-less barley flour water-unextractable AX. Fractionation of AS-AX by stepwise ethanol precipitation resulted in structurally different hull-less barley flour AS-AX fractions. Their A/X ratios increased with increasing ethanol concentration, and this increase in A/X ratio was reflected in their xylose substitution levels. For both XAA and XBS, the enzymic degradability of AX and apparent specific endoxylanase activity decreased with increasing A/X ratio of the AS-AX substrates, implying that both endoxylanases were sterically hindered by arabinose substituents. However, for all AS-AX fractions, hydrolysis end products of lower average degree of polymerization were obtained after incubation with XAA than with XBS, indicating that the former enzyme has a lower substrate specificity toward hull-less barley flour AS-AX than the latter. In addition, apparent specific endoxylanase activities indicated that XBS was approximately 2 times more sensitive to variations in the A/X ratio of AS-AX fractions than XAA. Furthermore, AS-AX with higher A/X ratio were relatively resistant to degradation by XBS.     

Cool‐Season annual legume effects on wheat forage nutritive value

Hard red winter wheat (Triticum aestivum L. emend. Thell.) is an important cool‐season winter forage used primarily for increasing weight gain on growing beef cattle in the southern Great Plains. ‘Karl’ hard red winter wheat grown alone or grown with either hairy vetch (Vicia villosa Roth) or pea [(Pisum sativum L. subsp. arvense) var. ‘Austrian winter'] was sampled for forage nutritive value. The interplanted legume forage was also sampled for forage nutritive value. Ruminally degradable nitrogen (RDN):ruminally degradable organic matter (RDOM) ratios were highest for legume forage and exceeded the National Research Council (NRC) recommendation of 26.13 g RDN: 1 kg RDOM for peak ruminai microbial efficiency during March, April, and May sample periods over the 2‐year study. Wheat grown alone met the NRC requirement only during March. Wheat grown with either hairy vetch or pea had higher (P<0.05) RDN:RDOM ratios and crude protein (CP) values when compared to wheat grown alone during May. There were no differences (P>0.05) in dry matter (DM) yield between wheat grown alone or grown with the legumes except when analyzed by individual date, and then only for 1 of 6 sample dates. Undegraded intake protein (UIP) was generally higher (PO.05) for wheat compared to the legumes and higher (PO.05) for wheat grown alone during May compared to wheat grown with the legumes during May. The decline of the RDN:RDOM values to 40% below the NRC recommendation of wheat grown alone during May indicates a possible need for protein supplementation for growing beef cattle grazing wheat during this period. These data also indicate that interplanting legumes with wheat may enhance animal performance by providing forage of higher nutritive value. More information regarding grazing tolerance of these selected cool‐season annual legumes and subsequent animal performance is required.     

食用菌栽培对棉籽壳营养价值及山羊瘤胃动态降解率的影响

为了研究4种食用菌栽培后对栽培基质棉籽壳的营养价值和山羊瘤胃动态降解率的影响,选用6只年龄(10月龄)、体重[(35.42±3.96)kg]接近并装有永久瘤胃瘘管的槐山羊羯羊,通过化学分析法测定了棉籽壳和4种菌糠的化学成分,并采用尼龙袋技术,分5批次测定了棉籽壳、平菇菌糠、木耳菌糠、金针菇菌糠和白灵菇菌糠瘤胃动态降解率。结果表明:(1)4种菌糠干物质(DM)和有机物(OM)含量分别比其栽培原料棉籽壳的含量降低13.09%~19.67%(P<0.01)和14.13%~39.52%(P<0.01),粗蛋白(CP)含量分别比棉籽壳提高40.20%~34.29%(P<0.01),中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量分别比棉籽壳降低3.07%~39.72%和17.80%~45.91%(P<0.01);(2)木耳菌糠、金针菇菌糠、白灵菇菌糠的DM和OM在瘤胃内的有效降解率和a+b值(快速降解部分和慢速降解部分之和)均极显著高于棉籽壳(P<0.01),平菇菌糠的DM和OM在瘤胃内的有效降解率显著高于棉籽壳(P<0.05);平菇菌糠、金针菇菌糠、白灵菇菌糠的CP在瘤胃内的有效降解率和a+b值均极显著高于棉籽壳(P<0.01);4种菌糠的NDF和ADF在瘤胃内的有效降解率分别比棉籽壳提高76.72%~702.63%(P<0.01)和137.41%~575.31%(P<0.01)。因此,在棉籽壳上栽培4种食用菌均能改善棉籽壳的营养价值和提高山羊瘤胃消化率,栽培食用菌后的菌糠更有利于作为反刍动物饲料进行利用。     

Effect of thyme essential oils (Thymus hyemalis and Thymus zygis) and monensin on in vitro ruminal degradation and volatile fatty acid production

The effect of the essential oils of thyme on the in vitro ruminal degradability of a barley seed/alfalfa hay substrate was studied. Two essential oils were used, one from Thymus hyemalis (TH), rich in carvacrol, and the other from Thymus zygis (TZ), rich in thymol. Four experimental treatments of in vitro degradability, using the Daisy II(200/220) incubator, were conducted including a negative control (CO), a positive control at 7.5 microg/mL of monensin (MO), and two treatments with essential oils (TH or TZ) at 1.35 microL/mL. The material was incubated at 39.5 degrees C for various lengths of time. At each time, the disappearance of dry matter, crude protein, and neutral detergent fiber was measured. Volatile fatty acids (VFAs) were determined after 48 h of incubation. CO and MO provided (p < 0.01) higher values of potential degradability (a + b) of DM than the TH and TZ treatments (72.6 and 70.8 vs 53.2 and 48.2%, respectively). Also, crude protein degradability was lowest in the essential oil treatments. The CO treatment showed the highest potential degradability of NDF. The values of VFA production obtained (p < 0.001) with CO and MO treatments were higher than those obtained with TH and TZ treatments (21.0 and 19.1 vs 11.2 and 10.1 mM). The essential oils decreased the molar proportion of propionate, increasing the acetate/propionate ratio. In conclusion, the effects of essential oils at assayed doses would not be nutritionally beneficial to the ruminal energetic metabolism.     

Wet Processing of Barley Grains into Concentrates of Proteins, β‐Glucan,and Starch

An improved wet method was developed to process barley into fractions concentrated in protein, (1‐3)(1‐4)‐β‐d ‐glucan (BG), starch, or other carbohydrates (CHO). Alkaline concentration, solvent to barley flour ratio (SFR), and extraction temperature were evaluated for their effects on concentration and recovery of protein, BG, starch, oil, ash, and other CHO in each fraction type. Results show that the three parameters and their interactions all had significant effects, resulting in varying nutrient concentrations and recovery rates in each type of fractions. For protein fractions, protein content varied from 37.7 to 75.2%, protein recovery from 8.5 to 75.7%, and increasing alkaline concentration and SFR improved nutrient recovery. For BG fractions, BG content ranged from 21.5 to 87.0%, BG recovery from 28.6 to 78.0%, and increasing alkaline concentration decreased BG content but increased its recovery significantly. For starch fractions, starch content varied from 76.9 to 93.9%, starch recovery from 33.6 to 63.9%, and all parameters had little effect on the nutrient concentrations, but alkaline concentration and SFR improved recovery of starch, other CHO, and mass. Overall, the improved wet method was effective in concentrating the major nutrients from barley into their respective fractions, but process optimization through manipulating the three parameters is necessary to achieve a maximum concentration or recovery rate of a nutrient of interest in a specific fraction.     

In vitro antioxidant activities of barley, husked oat, naked oat, triticale, and buckwheat wastes and their influence on the growth and biomarkers of antioxidant status in rats

The study was aimed at verification of the following hypothesis: differences in antioxidant capacity of diets consisting of different cereals and byproducts affect the antioxidant status of the consumers of these diets. To validate that hypothesis this study investigated the contents of polyphenols and alpha-tocopherol as well as the total antioxidant capacity (TAC) in vitro of cereals and their fractions (barley, husked and naked oat, oat bran, and triticale); the nutritional and antioxidant properties of diets containing these cereals, applied in a 4-week feeding experiment on rats, were also assessed. Among the cereals examined, the highest TAC was reported for barley (13.16 micromol of Trolox/g) and the lowest for naked oat (3.84 micromol of Trolox/g). Compared with cereals, the TAC of buckwheat waste was 2-3 times higher (25.2 micromol of Trolox/g). The antioxidant capacity of diets, calculated in vitro, ranged from 6.35 micromol of Trolox/g for naked oat type diet to 10.51 micromol of Trolox/g for barley type diet. Results of an in vitro study were confirmed in changes of glutathione peroxidase (GPx) activities and the level of thiobarbituric acid-reactive substances (TBARS) in the serum of rats fed diets with the highest and lowest antioxidant capacities in vitro; the barley diet increased the activity of GPx (37.63 units/mL) and decreased the level of TBARS (4.82 microg/g), whereas the naked oat diet had an opposite effect (31.16 units/mL and 5.91 microg/g, respectively).     

蛋氨酸硒对西门塔尔牛瘤胃发酵及尿嘌呤衍生物的影响

选用4头平均体重420 kg、年龄2.5岁装有永久性瘤胃瘘管的西门塔尔牛阉牛,采用4x4拉丁方设计,以混合精料和风干玉米秸秆为基础日粮,以蛋氨酸硒为硒源,在基础日粮中分别添加硒0 mg·kg-1、0.3mg·kg-1、0.6 mg·kg-1和0.9 mg·kg-1,研究蛋氨酸硒对西门塔尔牛瘤胃pH、氨态氮、VFA、营养物质降解率及尿嘌呤衍生物浓度的影响.结果表明:不同浓度硒处理间西门塔尔牛瘤胃pH、挥发性脂肪酸(VFA)和乙酸,丙酸无显著差异(P>0.05),氨态氮浓度显著低于对照(P<0.05);0.6mg·kg-1硒处理组西门塔尔牛玉米秸秆干物质(DM)、有机物质(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和豆粕DM、OM、粗蛋白质(CP)有效降解率均显著高于对照(P<0.05);0.6mg·kg-1和0.9mg·kg-1硒处理组西门塔尔牛尿囊素和尿嘌呤衍生物浓度显著高于0.3 mg·kg-1组和对照组(P<0.05);西门塔尔牛日粮以蛋氨酸硒为硒源时,硒的适宜添加浓度为0.6 mg·kg-1.     

饲料蛋白质水平对刺鲃幼鱼的生长、胴体营养组成及消化酶活性的影响

配制蛋白质水平20%~50% 的7种等能半精制实验饲料,饲养平均初始体重为1.26±0.02 g 的7组3重复的刺鲃(Barbudes caldwell)幼鱼8周,研究刺鲃对饲料蛋白的需求量。结果显示,饲料蛋白水平对实验鱼的成活率、脏体比和肝体比等均无显著影响(P >0.05),而对鱼体终重有显著影响(P <0.05);鱼体增重和生长比速均随饲料蛋白水平从20%升高到35%而不断提高,但饲料蛋白水平进一步提高,则鱼体增重和生长比速均无显著差异(P >0.05)。饲料蛋白水平30%～50%的5个实验组的饲料效率无显著差异(P>0.05), 但均显著高于饲料蛋白为20%和25%的2个实验组(P <0.05)。蛋白质效率(PER)与饲料蛋白水平(x)呈负相关(PER= 3.006－0.03251x, R =0.9366)。饲料蛋白水平对鱼体的胴体水分、粗蛋白和粗灰分的含量无显著影响(P > 0.05);胴体脂肪含量随饲料蛋白水平(x)的升高而不断降低(L=8.2169－0.0458x,R =0.8551)。实验鱼肝胰脏蛋白酶活性则在组间无显著差异(P > 0.05)。肠蛋白酶和肝胰脏淀粉酶活性均随着饲料蛋白水平的升高而呈现先逐渐升高,且升高到一定程度后又呈逐渐下降的趋势。肠淀粉酶活性(IAA)与饲料蛋白水平(x)呈负相关关系(IAA = 84.625－0.9147x, R =0.8463,)。以鱼体增重为指标(y),与饲料蛋白水平(x)拟合折线模型进行回归分析,估算出饲料蛋白质适宜水平为占干饲料的34%。     

Selenium accumulation in beef: effect of dietary selenium and geographical area of animal origin

Selenium (Se) is an essential nutrient with multiple human health benefits; the single most important dietary source of Se is beef. The Se content of beef varies, and cattle fed a high selenium diet may have Se concentrations in beef that are well above average. Such beef is potentially a unique supplemental source of dietary Se. To examine factors affecting Se accumulation in beef, 16 steers (initial wt 374.4 +/- 33.7 kg) were taken from seleniferous or nonseleniferous areas and fed in a 2 x 2 factorial design with diets high or moderate in Se (11.9 or 0.62 mg Se/kg diet). Diets contained 50% alfalfa, 25% wheat, and 25% corn on a dry matter basis. All dietary Se was from agricultural products, and Se in the high Se diet was primarily from high Se wheat and alfalfa hay. A loin muscle biopsy was taken at the start of the trial to determine initial Se content of beef. Steers were slaughtered after 14 weeks of the trial, and edible carcass (round, sirloin, shoulder clod, and ribeye) and organ samples were collected. Diets did not affect growth or feed intake (P > 0.05), and Se toxicity signs were not observed. Different cuts of meat had similar Se concentrations, and the Se content of all cuts was increased by both high dietary Se and high Se background. Except for liver and kidney, Se in tissues was increased by seleniferous background (P < 0.02) and high dietary Se (P < 0.001). Kidney Se concentrations of animals fed the high Se diet were lowest in animals from seleniferous areas (P = 0.04), suggesting a possible adaptation to the high Se diet. These results demonstrate that cattle fed diets high in Se from agricultural products will accumulate substantial amounts of Se in the beef without developing signs of Se toxicity and that prior Se status regulates Se accumulation in some organs. They further demonstrate that management practices may be altered so as to make beef a significant source of dietary Se.     

Nutritional and sensory evaluation of akara made from blends of cowpea and hard-to-cook mottled brown dry beans

The effect of replacing cowpea with hard-to-cook beans on the nutritional and sensory properties of akara were evaluated. Cowpea (Vigna unguiculata), traditionally used for making akara, was substituted 0%, 25%, 50%, 75%, and 100% with hard-to-cook (HTC) mottled brown beans (Phaseolus vulgaris). Cowpea (CP) soaked for 60 min HTC beans soaked for 18 h were separately decorticated, ground to a paste, and mixed in the following CP:MBB ratios: 0:100, 25:75, 50:50, 75:25, and 100:0. The paste mixtures were each whipped and fried into akara. The samples were analyzed for bulk density, nutritional composition, carbohydrate and protein digestibility, alpha-amylase inhibitor and trypsin inhibitor activity, and sensory attributes. The bulk density of paste as well as of akara increased with the increasing content of HTC bean. Akara made from composite paste had a relatively better amino acid profile. Frying beyond 5 min destroyed the alpha-amylase inhibitors as well as the trypsin inhibitor activity. No significant difference was observed in the overall acceptability of akara made from cowpea substituted up to 50% with HTC beans. Hence, this approach permits the utilization of hard-to-cook beans.     

Effects of split nitrogen fertilization on post-anthesis photoassimilates,nitrogen use efficiency and grain yield in malting barley

Abstract

Split nitrogen applications are widely adopted to improve grain yield and enhance nitrogen use effective in crops. In a two-year field experiment at two eco-sites, five fractions of topdressed nitrogen of 0%, 20%, 30%, 40% and 50% were implemented. Responses of radiation interception and leaf photosynthesis after anthesis, dry matter accumulation and assimilates remobilization, nitrogen use efficiency and grain yield to fraction of topdressed nitrogen treatments were investigated in malting barley. Net photosynthetic rate of the penultimate leaf, leaf area index and light extinction coefficient increased with increasing fraction topdressed nitrogen from 0% to 30%, and then decreased from 30% to 50%. The putative gross maximum canopy photosynthesis was the highest for fraction of topdressed nitrogen of 30%, which was concomitant with the highest amount of post-anthesis accumulated assimilates. The remobilization of pre-anthesis stored assimilates from vegetative organs into grains was hardly significantly affected by fractions of topdressed nitrogen. Grain yield was the highest for fraction of topdressed nitrogen of 30%, which coincided with the highest plant nitrogen uptake and physiological and agronomic nitrogen use efficiencies. The enhanced nitrogen use efficiency was corresponding to the improved photosynthetic nitrogen-use efficiency in the leaves at fraction of topdressed nitrogen of 30%. In conclusion, appropriate fraction of topdressed nitrogen application on malting barley improved assimilation rate and nitrogen use efficiency resulting in higher grain yields and proper grain protein content in malting barley.     

Air Classification of Barley Flours

Flour samples from seven different barleys, including covered and naked barleys and barleys with normal, waxy, and high‐amylose starches, as well as the high fiber barley Prowashonupana, were impact‐milled and air‐classified in a pilot unit. Six fractions (F1–F5 and C5) with increasing particle size were obtained from each barley. All fractions were analyzed for ash, protein, starch, dietary fiber, and total and unextractable β‐glucan. Ash was enriched in C5; covered barleys (4.3–5.7% of dry matter) had a higher ash content than naked barleys (2.1–3.2%). Starch was enriched in F4 for normal and waxy barleys (72–79%) and in F3 for high‐amylose barleys (72–75%). Protein was enriched in F1 (14–26%) for the different barleys. β‐glucan was enriched in F5 and C5 (7–23%), Prowashonupana had the highest value. The extractability of β‐glucan decreased with increasing particle size, probably because of lower amounts of endogenous β‐glucanase and poorer availability of the substrate in larger particles.     

Contributions from carbon and nitrogen in roots to closing the yield gap between conventional and organic cropping systems

This study investigates the effect of different crop rotation systems on carbon (C) and nitrogen (N) in root biomass as well as on soil organic carbon (SOC ). Soils under spring barley and spring barley/pea mixture were sampled both in organic and conventional crop rotations. The amounts of root biomass and SOC in fine (250–253 μ m), medium (425–250 μ m) and coarse (>425 μ m) soil particulate organic matter (POM ) were determined. Grain dry matter (DM ) and the amount of N in harvested grain were also quantified. Organic systems with varying use of manure and catch crops had lower spring barley grain DM yield compared to those in conventional systems, whereas barley/pea showed no differences. The largest benefits were observed for grain N yields and grain DM yields for spring barley, where grain N yield was positively correlated with root N. The inclusion of catch crops in organic rotations resulted in higher root N and SOC (g C/m²) in fine POM in soils under barley/pea. Our results suggest that manure application and inclusion of catch crops improve crop N supply and reduce the yield gap between conventional and organic rotations. The observed positive correlation between root N and grain N imply that management practices aimed at increasing grain N could also increase root N and thus enhance N supply for subsequent crops.     

The effect of cobalt stress on growth and physiological traits and its association with cobalt accumulation in barley genotypes differing in cobalt tolerance

Cobalt (Co) is beneficial for legume plants and not an essential element for most plants. There is no sufficient information about the effect of Co stress on barley growth. The current experiment was carried out to investigate the effects of different Co levels (25, 50, 75, and 100 µM) on growth and physiological traits of three barley genotypes (B325, J36, and B340) differing in Co tolerance. The results showed that Co stress inhibited plant growth, decreased chlorophyll content and photosynthetic rate, and enhanced oxidative stress. However, the effects differed among genotypes, with B325 and B340 being the most and the least affected, respectively. Co stress caused decrease and increase of manganese (Mn) and phosphorus (P) concentrations in both roots and shoots, respectively; iron (Fe) concentration had little change in shoots and a significant decrease in roots. The current results showed a close association of Co tolerance and its accumulation in plant tissues.     

Silicon Increases Tolerance to Boron Toxicity and Reduces Oxidative Damage in Barley

ABSTRACT

Silicon (Si) protects plants from multiple abiotic and biotic stresses The effect of exogenous Si levels (50, 75, and 100 mg kg^?1) on the growth, boron (B) and Si uptake, lipid peroxidation (MDA), lipoxygenase activity (LOX; EC 1.13.11.12), proline, and H₂O₂ accumulation, non-enzymatic antioxidant activity (AA) and the activities of major antioxidant enzymes (superoxide dismutase, SOD, EC 1.15.1.1; catalase, CAT, EC 1.11.1.6 and ascorbate peroxidase, APX, EC 1.11.1.11) of barley (Hordeum vulgare L.) were investigated under glasshouse conditions. Increasing levels of Si supplied to the soil with 20 mg kg^?1 B counteracted the deleterious effects of B on shoot growth. Application of B significantly increased the B concentration in barley plants. However, Si application decreased B concentrations. Increasing application of Si increased the Si concentration in barley plants. The concentration of H₂O₂ was increased by B toxicity but decreased by Si supply. Boron toxicity decreased proline concentrations and increased lipid peroxidation (MDA content) and LOX activity of barley. Compared with control plants, the activities of AA, SOD, CAT, and APX in B stressed plants grown without Si decreased, and application of Si increased their activities under toxic B conditions. The LOX activity was decreased by Si. Based on the present work, it can be concluded that Si alleviates B toxicity by possibly preventing oxidative membrane damage, both through lowering the uptake of B and by increasing tolerance to excess B within the tissues.