Phänotyp und Futterqualitat einschliefilich Konservierungseigenschaften bei Grasern

Phenotype and forage value, including conservation properties, of grasses The phenotype of grasses can be influenced by the date of harvest as well as by breeding programs. In contrast to dicotyledons, the stems of grasses are younger than the leaves, although the grass leaves are usually considered to have a higher nutritional value than the stems. In a field experiment, Lolium multiflorum Lam. ssp. gaudini (Parl.) Schinz et Kell. was grown as a model-plant in order to study effects of ploidy-level, N-fertilization, stage of development, and growth time on the main aspects of nutritional value and conservation properties in relation to the phenotype. As regards the nutritional value, the interactions of ploidy × plant organ (=stem or leaf) and of ploidy × N-input were not significant. Hence, the results for leaf and stem can be generahzed. Until the emergence of the inflorescence, EC 49, the stem showed a significant higher net energy content than the leaf; at later stages of development this relationship changed. The evaluation of the net energy content of leaf and stem was significantly influenced by the method of estimation. In vitro methods with rumen liquor may show the best approximation to the real value. The crude protein/energy ratio of the stem as compared to the leaf better meets the nutritional requirements of ruminants; on the other hand the leaf was more valuable than the stem in relation to the nitrate content, especially when the whole plant showed an increased nitrate level. The general relationship between the mineral content and the phenotype was not evident. The investigation indicated significant differences between stem and leaf in relation to their conservation properties. The leaf showed more favourable drying properties than the stem but ensilability was better for the stem than for the leaf. As a result of this investigation it is assumed that, in the past, the nutritional value of young stem has been underestimated whereas the value of the leaf has been overemphasized. This may also be due to the criteria and determination methods of the nutritional value.     

Storage and Remobilization of Soluble Carbohydrates after Heading in Different Plant Parts of a Winter Wheat Cultivar

Abstract

Several types of water soluble carbohydrates (WSG) were traced into plant parts of a winter wheat (Triticum aestivum L.) cultivar from heading to physiological maturity. Field grown plants were harvested at intervals of a few days and divided into grain, chaff, leaf blades, leaf sheaths, rachis + peduncle and culm internodes. Leaf blades and sheath showed the peak of WSC contents at about anthesis. Culm internodes accumulated fructan and sucrose during the early grain-filling phase, from a week after anthesis until the milk-ripe stage, then remobilized them during late and final grain filling phases, from the milk-ripe stage until maturity. The amount of sucrose known as short-term storage WSC was higher than fructan known as long-term storage WSC in each internode throughout the grain-filling phase. Chaff showed a large amount of fructan and fructose before anthesis, although it did very little sucrose. A pattern of sucrose accumulation in chaff was very different from that of fructan, unlike the other parts. These patterns of changes in WSC contents in plant organs roughly corresponded with four grain-filling phases, the initial, early, late and final phases.     

Protein degradation and fermentation characteristics of unwilted red clover and alfalfa silage harvested at various times during the day

Extensive proteolysis during fermentation of high‐protein legumes reduces dietary N‐use efficiency in ruminants. Research has demonstrated that enhancing the level of fermentable carbohydrates in crops entering the silo may reduce protein degradation by increasing the rate of decline in pH. The objective was to evaluate whether delaying cutting time during the day, to allow accumulation of total non‐structural carbohydrates (TNC), would inhibit proteolysis in the silo. Red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) were harvested at 06.00, 10.00, 14.00 and 18.00 hours in 1993, 1994 and 1995, and ensiled without wilting. TNC accumulated in fresh forage during the day, with starch accounting for more than 0·50 of the daily change in TNC in fresh herbage of both species, except in red clover in 1995. The level of TNC in fresh forage did not consistently affect the extent of protein degradation in either species and, in all instances, alfalfa underwent more extensive proteolysis than red clover. Silage pH typically decreased and starch concentration increased as cutting time was delayed from 06.00 to 18.00 hours. Although the extent of proteolysis was largely unaffected by inherent increases in TNC, harvesting in the afternoon did provide several benefits including increased dry‐matter content, lower silage pH and higher starch concentrations. Effluent production is a concern in any unwilted silage system; there was therefore an added advantage of lower moisture content from cutting in the afternoon.     

Impact of frost and plant age on compensatory growth in timothy and perennial ryegrass during winter

Two cultivars of each of two contrasting grass species, timothy ( Phleum pratense L.) and perennial ryegrass ( Lolium perenne L.), sown either in May or July, were sampled for dry matter (DM) weight of roots and herbage in late October (end of main growing season) and examined for regrowth when exposed to a frost treatment (−8 to −10°C in darkness for 48 h) in late January, early March and late April. The frost treatment caused compensatory root and herbage growth, and regrowth of roots in March and April was greater than regrowth of herbage. Early-sown plants had higher DM weights of roots and herbage than late-sown plants in October but had the lowest survival rate when exposed to the frost treatment in April. Compensatory growth of root and herbage in response to moderate frosts occurred in January and March in all cultivars, and in the most frost-resistant timothy cultivar in April. Concentration of total carbohydrates increased from October to March with the greatest increase in the most winter-hardy cultivar of each species, and then decreased in April. An indirect correlation between concentration of total carbohydrates and tolerance to moderate frost was indicated, and plant survival and ability for compensatory growth were also associated with differences in adaptation related to winter survival in the cultivars tested.     

Buckwheat Seed Milling Fractions: Description, Macronutrient Composition and Dietary Fibre

The structure of the mature buckwheat achene and groat is discussed in relation to milling fractions and nutritional composition. Whole groats contain 55% starch, 12% protein, 4% lipid, 2% soluble carbohydrates, 7% total dietary fiber (TDF), 2% ash, and 18% other components (organic acids, phenolic compounds, tannins, phosphorylated sugars, nucleotides and nucleic acids, unknown compounds). The composition of the milling fractions reflects the relative abundance of seed tissues. Starch is concentrated in the central endosperm. Protein, oil, soluble carbohydrates and minerals are concentrated in the embryo. Commercial «Fancy» flour, a light-coloured flour, is mostly central endosperm and contains 75% starch, 6% protein, 1% lipid, 1% soluble carbohydrates, 3% TDF, 1% ash, and 13% other components. Although the embryo traverses the central endosperm, during milling parts of the embryo separate with the aleurone and seed coat in the bran fraction. Bran, with little central endosperm, contains 18% starch, 36% protein, 11% lipid, 6% soluble carbohydrates, 15% TDF, 7% ash, and 7% other components. Buckwheat bran also is a rich source of TDF and soluble dietary fibre (SDF), particularly bran with hull fragments (40% TDF of which 25% is SDF), while bran without hull fragments has 16% TDF of which 75% is SDF.     

Starch and lipid in diets for dourado Salminus brasiliensis (Cuvier 1816): growth,nutrient utilization and digestive enzymes

Carbohydrates and lipids are the major and cheaper non‐protein energy sources for fish diets. This study aimed at determining ideal relationship between dietary starch and lipids and their influence on digestive enzyme profile of juvenile dourado. Trials were set up in a closed‐loop system with controlled temperature, dissolved oxygen, pH and total ammonia. Experimental extruded diets formulated to contain different starch (St) to lipids (Lip) ratio (St : Lip = 0 : 1, 0.3 : 1, 0.7 : 1, 1.0 : 1, 1.4 : 1, 2.0 : 1, 2.3 : 1 to 3.3 : 1) were fed to juvenile dourado (3.34 ± 0.16 g) and stocked into 30 polyethylene tanks (330 L, 30 fish per tank) in a completely randomized design with unbalanced repetition (n = 3 or 4), in two daily meals (1000 and 1530) until satiation, for 95 days. Dietary starch contents higher than 145.2 g kg^‐1 (St : Lip > 1.0 : 1.0) hampered the performance of fish, but, paradoxically, the inclusion of carbohydrates in the diet elicited better utilization of dietary protein and energy by the species. Fish adapted digestive enzyme profile to dietary starch contents through increasing secretion of alkaline proteases and non‐specific lipases, but secretion of amylase was not altered. Physiological responses show the limitation of species on the use of dietary carbohydrates.     

Effects of the protein/carbohydrate ratio of extruded diets on protein synthesis, protein growth and body composition in juvenile brown trout (Salmo trutta)

High levels of protein in fish feeds result in higher costs and nitrogen waste. Therefore, studies focused on protein substitution by alternative energy sources are necessary. Here we examine whether the protein:carbohydrate ratio in extruded diets affects protein-turnover parameters and the main tissue components in brown trout. Juvenile fish were adapted to two extruded diets: one higher in protein and lower in carbohydrate, C: 45/28 and the other higher in carbohydrate and lower in protein, HC: 37/40. Gross energy was 19 MJ kg⁻¹ DM in both diets. Protein and lipid digestibility were high and similar in both groups (≈90%), whereas total and carbohydrate digestibility and digestible energy were lower in the HC-fed group than in the C-fed group. Consequently, when fish were adapted to the diets, plasma levels of glucose and insulin differed between diets. HC-group presented higher plasma glucose levels and lower plasma insulin levels than C-group. Protein synthesis rates in white muscle, liver and whole body did not differ significantly between diets. In contrast, protein accretion rate of white muscle and whole body were significantly lower in the HC group, indicating an increase of protein degradation in these tissues and a decrease of synthesis retention efficiency. In spite of the daily protein intake of HC group was lower than C-group, the anabolic stimulation efficiency was increased by 34% in HC group. Protein and lipid contents in white muscle and liver were stable throughout the experiment. No hepatomegalia or increased fat deposition was observed in fish fed HC. Differences in specific growth rates (C: 0.88%; HC: 0.77%) were associated more with the lower protein consumption rate and the lower level of digestible energy in fish fed HC than with the higher dietary carbohydrate content of the diet.     

高温胁迫对黄瓜幼苗N素及C素代谢的影响

高温胁迫 ３ ｄ 后,黄瓜耐热品种津杂 ２ 号幼苗中蛋白质降解速率（４．３６％ ）比不耐热品种中农 １１ 号（８．５１％ ）慢;氨基酸增幅较小,耐热品种为 ２６．３４％ ,不耐热品种为 ３４．７％ ,其中脯氨酸质量分数增幅与品种耐热性呈正相关．耐热品种比不耐热品种具有较高的净光合速率（分别为７．６６、６．６４ μｍ ｏｌ·ｍ － ２·ｓ－ １）,较低的呼吸速率（分别为４４５．６６、５６３．４９ μ Ｌ·ｇ－ １ ·ｈ－ １）和乙醇酸氧化酶活性［△ Ｄ（６２０ ｎｍ ）分别为２．０２、２．４２］．解除高温胁迫后,耐热品种的蛋白质合成和净光合速率均较不耐热品种恢复得快,表明耐热品种无论在高温胁迫下或解除胁迫后均比不耐热品种具有较强的平衡 Ｎ、 Ｃ代谢的能力     

不同种源北美香脂杨苗木碳水化合物积累差异分析

对9个不同种源的北美香脂杨在加拿大温哥华扦插繁殖的苗木枝条进行分析,分另4测定带芽枝条可溶性糖、淀粉、糖组分的含量,扦插后萌发的叶干质量和根干质量。结果表明：不同种源枝条的可溶性糖和淀粉含量差异极显著;扦插生根和叶的干质量与淀粉含量间呈现正相关关系,与各地的地理位置（纬度、经度、海拔）无显著相关性;不同种源枝条内淀粉含量与其扦插生根特性呈正相关关系。     

Grain weight response to foliar diseases control in wheat (Triticum aestivum L.)

Foliar diseases are the main biotic restriction reducing yield in wheat crops affecting both, grain number and/or grain weight, depending on developmental stage at which infection occurs (pre- or post-anthesis, respectively). Grain weight reductions due to foliar diseases were widely reported in the literature mostly associated with decreases on radiation interception during the grain filling period. However, different evidences in wheat showed variations on grain weight responses when fungicide was applied during the grain filling period, probably associated with the timing of fungicide application or with the amount of available resources per grain set when fungicides are applied. The present study was designed to determine the causes of grain weight reduction due to foliar diseases complex (including leaf rust, Septoria leaf blotch and tan spot) in wheat crops growing under contrasting agronomic and environmental conditions (i.e. different years, locations, cultivars and N supply). The experiments were carried out during 4 years under field conditions in different locations of Argentine and France. Five different commercial wheat cultivars were sown on early and late sowing dates; and two contrasting N availability and two fungicide treatments (protected and unprotected) were applied. Grain number was not affected by foliar diseases as their appeared after anthesis. Grain weight was strongly, poorly or not affected by foliar diseases and was not associated individually with both, the sink size and the source size. However, when the grain weight response due to fungicide application was plotted against the healthy area absorption per grain (HAA_G), a significant negative association (r² = 0.81; p < 0.0001) was found for the Argentine experiments. When the HAA_G was corrected by the grain weight potential (HAA_GW) all experiments conduced in Argentine and in France fit well to a common negative linear regression (r² = 0.74, p < 0.0001) for the relationship between grain weight variation and HAA_GW demonstrating that grain weight potential is an important feature to consider in diseases control programs. Foliar diseases forced the crop to use the accumulated reserved increasing the utilization rate of the water soluble carbohydrates (WSC_UR), depleting as a consequence the water soluble content at physiological maturity (WSC_PM) in all experiments. The association between WSC_UR and the healthy area absorption per grain corrected by grain weight of healthy crops (HAA_GW) suggest that foliar diseases in wheat cause source limitation, forcing to the crop to use the WSC reserve which could be insufficient to fill the grains previously formed.