不同养殖模式翘嘴鲌肌肉营养品质比较

为评价池塘与大湖不同养殖模式翘嘴鲌(Culter alburnus)肌肉营养品质差异,试验分析了商品翘嘴鲌肌肉常规营养成分、氨基酸、脂肪酸、矿物元素含量等营养指标。结果表明:大湖翘嘴鲌肌肉水分含量显著低于池塘翘嘴鲌(P<0.05),粗蛋白质含量高于池塘翘嘴鲌,差异不显著(P>0.05)。池塘与大湖翘嘴鲌肌肉,除了赖氨酸和组氨酸以外(P<0.05),绝大部分氨基酸含量均无显著性差异(P>0.05)。大湖翘嘴鲌肌肉的总氨基酸、必需氨基酸和鲜味氨基酸含量分别较池塘翘嘴鲌高出2.72%、2.87%和2.50%。根据氨基酸评分(AAS)和化学评分(CS)结果,池塘与大湖翘嘴鲌肌肉中第一限制性氨基酸均为蛋氨酸+胱氨酸,赖氨酸相对含量最高,必需氨基酸指数(EAAI)分别为68.81和69.62。池塘翘嘴鲌的棕榈油酸(C16:1)含量显著高于大湖翘嘴鲌(P<0.05),而大湖翘嘴鲌肌肉的单不饱和脂肪酸(MUFAs)、高不饱和脂肪酸(HUFAs)、必需脂肪酸(EFA)、EPA+DHA含量则高于池塘翘嘴鲌(P>0.05)。试验检测了池塘与大湖翘嘴鲌肌肉11种矿物元素,其中镁有显著差异(P<0.05),重金属元素(铬、镉、铅)含量均在限量范围以内。综上所述,大湖养殖翘嘴鲌营养品质优于池塘养殖。     

香梨果园套种苏丹草对土壤养分及产草量的影响

探讨库尔勒香梨果园套种苏丹草对果园土壤性状的影响和产草量。果园内,分别设距树干0.5m处外和1.5m处外2个采样区,测定采样区内苏丹草产量和0~60cm土层的土壤容重及土壤养分。结果表明,离树干1.5m处外干草产量为2.25kg/m^2,显著高于离树干0.5m处外的1.34kg/m^2。离树干0.5m处外0~20、20~40cm土层地下生物量分别为81.26g/m^2、14.38g/m^2约为离树干1.5m处213.62g/m^2、32.89g/m^2的38.03%、56.27%,且90%以上的牧草根量分布在0~20cm的果园土层,苏丹草与果树的根系几乎无重叠现象。可见,香梨果园套种苏丹草对土壤性状及养分无负面影响,1a可以收草3次,其产草量可达大田产量的60%左右。     

Clay mineralogical and ammonium fixation characteristics of some tropical upland rice soils

Abstract

In view of the agronomic and economic significance of NH₄ fixation in soils, an attempt has been made to relate this to the most reactive mineral constituents of soils ‐ the clay minerals, under the temperature‐moisture regimes normal to tropical upland rice soils. Laboratory fixation study was done with NH₄, concentrations similar to those common in soils upon N fertilization, and under alternate wetting and drying at ambient temperatures rather than at 100°C as in many published studies.

Results of the investigation show that soil clays with dominant vermiculite and montmorillonite fix the greatest proportion of applied NH₄ (94 and 91%), followed by beidellite (72%) and x‐ray amorphous (45–64%) clays. Fixation is negligible (10%) in the clay with mineral suite consisting of hydrous mica, halloysite, and chlorite. Crystallinity of minerals seems to influence NH₄ fixation appreciably.     

Potential of imaging spectroscopy as tool for pasture management

The use of imaging spectroscopy to predict the herbage mass of dry matter (DM), DM content of herbage and crude fibre, ash, total sugars and mineral (N, P, K, S, Ca, Mg, Mn, Zn and Fe) concentrations was evaluated. The experimental system used measured reflectance between 404 and 1650 nm at high spatial (0·28–1·45 mm²) and spectral resolution. Data from two experiments with Lolium perenne L. mini‐swards were used where the degree of sward damage or N‐fertilizer application varied. Regression models were calibrated and validated and the potential reduction in prediction error with multiple observations was estimated. The mean prediction errors for DM mass, DM content and N, total sugars, ash and crude fibre concentrations were 235–268 kg ha^?1, 9·6–16·8 g kg^?1, 2·4–3·4 g kg DM^?1, 16·2–27·7 g kg DM^?1, 5·8–6·5 g kg DM^?1 and 8·4–10·4 g kg DM^?1 respectively. The predictions for concentrations of P, K, S and Mg allowed identification of deficiency levels, in contrast to the concentrations of Na, Zn, Mn and Ca which could not be predicted with adequate precision. Prediction errors of DM mass may be maximally reduced to 95–142 kg ha^?1 with 25 replicate measurements per field. It is concluded that imaging spectroscopy can provide an accurate means for assessment of DM mass of standing grass herbage. Predictions of macronutrient content and feeding value were satisfactory. The methodology requires further evaluation under field conditions.     

适宜无机盐及浓度抑制麦胚脂肪酶存在时油水界面张力

为了探明无机盐稳定化脂肪酶的潜在机理,该文以小麦胚芽脂肪酶为研究对象,基于界面酶学的分析方法,研究添加浓度介于1.0×10-9~1.0×10-2 mol/L的Na~+、K+、Ca~(2+)、Mg~(2+)的氯化物对小麦胚芽脂肪酶存在的油-水界面特性的影响。结果表明,当小麦胚芽脂肪酶体系浓度为1.7×10-6 mol/L时,一价金属中Na~+更有利于抑制油-水界面的表面张力(P0.05),对麦胚脂肪酶存在时的油水界面特性影响也较大;二价金属离子Ca~(2+)对界面张力的影响趋势与一价离子不同,在高浓度时反而增加界面张力;当油水界面上存在脂肪酶的催化底物(三油酸甘油酯)和产物(油酸)时,添加浓度分别为10-6、10-6、10-4和10-9mol/L的Na~+、K~+、Ca~(2+)、Mg~(2+)均可一定程度上降低油水界面张力,从而降低麦胚脂肪酶的作用效果,三油酸甘油酯存在时Mg~(2+)的作用效果最明显(P0.05),油酸存在时Na+的作用效果最明显(P0.05)。综上,无机盐金属离子主要通过影响麦胚脂肪酶在油水界面的聚集行为及底物结构状态起到钝化麦胚脂肪酶的作用,该结果可为麦胚脂肪酶存在时界面的活性调控及麦胚的稳定化处理提供参考。     

Herbage intake and ruminal digestion of dairy cows grazed on perennial ryegrass pasture either in the morning or evening

This study aimed to clarify diurnal fluctuations of herbage intake, ruminal fermentation of herbage carbohydrates and proteins, and digesta particulate weight in the rumen of grazing dairy cows. Six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture either in the morning (04.00 to 08.00 hours) or the evening (16.00 to 20.00 hours). Cows grazed in the evening spent more time (P < 0.01) and consumed more herbage (P < 0.01) compared with cows grazed in the morning. Higher (P < 0.05) daily mean concentrations of total volatile fatty acid, propionate and n‐butyrate in rumen fluid were observed for cows grazed in the evening compared with cows grazed in the morning. Although cows grazed in the evening ingested more crude protein compared with cows grazed in the morning, no significant difference in NH₃‐N concentration in rumen fluid was observed between them. The ratio of purine‐derivative concentration to creatinine concentrations was higher (P < 0.01) in the urine of cows grazed in the evening than in cows grazed in the morning. These results clearly indicated that evening grazing was advantageous for dairy cows compared with morning grazing, in terms of ruminal fermentable energy intake and nitrogen utilization efficiency.     

离子强度和磷酸盐对铁铝矿物及土壤吸附As（V）的影响

选用针铁矿、赤铁矿、水铁矿、水铝矿4种铁铝矿物以及性质差异较大的黑土、紫色土和红壤3种土壤,研究离子强度和磷酸盐对其吸附As（V）的影响。结果表明,在0．01、0．1、1mol·L^-13种离子强度下,矿物和土壤对As（V）的吸附量无明显差异或随离子强度增大而增大,其对砷的吸附以专性吸附为主。磷酸盐对矿物和土壤吸附砷的影响与其添加顺序及摩尔浓度比有关。水铝矿和水铁矿在这3种添加顺序下的砷吸附量无明显差异,仅在P／As摩尔比较大时表现出下降趋势;而在针铁矿和赤铁矿两种矿物上,先添加砷时的砷吸附量高于先添加磷时或两者同时添加时,且砷吸附量随WAs摩尔比的增加而逐渐下降。在黑土、紫色土和红壤上,先添加砷比先添加磷或两者同时添加时的砷吸附量均要高,尤其是在紫色土上。随P／As摩尔比升高,土壤对砷的吸附量表现出下降趋势。     

Compositional and Functional Properties of Saskatoon Berry and Blueberry

Abstract

Saskatoon berry (Amelanchier alnifolia Nutt., Rosaceae) and blueberry (Vaccinium corymbosum L., Ericaceae) are substantially equivalent in all characteristics that are important to the consumer, including fruit color, shape, size, nutrition, texture, and uses. In addition, both fruits are native to North America and they have practically identical historical uses and known health benefits. Their composition, processing, nutritional value and metabolism, intended uses, and levels of undesirable substances are compared.     

鲁梅克斯K-1牧草引种栽培试验研究初报

鱼梅克斯Ｋ－１牧草是河北省引进的一种多年生牧草，通过对该草的育苗移栽方式、生长发育规律、生物量测定、营养成分分析等研究，结果表明：鲁梅克斯Ｋ－１牧草是一种适应性强、营养价值高、繁殖力强的优质牧草。尤其收白质含量高达３８．９４％，生物量（鲜重）１５０ｔ／ｈｍ＾２，北方地区可大面积推广种植。     

Macro and trace elements of 26 browse species growing in semi-arid grazing lands of Eastern Cape,South Africa

ABSTRACT

Leaves and twigs from woody plants provide essential nutrients to range animals. We examined variation in the mineral status of 26 woody species, and the influence of harvesting height as well as the interactions of the main effects on minerals levels. Leaves were harvested from five individual plants per species at two height levels: low (<1 m) and upper (>1.5 m). For trees, all mineral levels showed variation (p < 0.05) between species. For shrubs and intermediate growth forms (between shrubs and trees), mineral levels except potassium (K) and zinc (Zn) were influenced (p < 0.05) by height × species interactions. Most browse species had calcium (Ca) contents (8.5–50 g kg^-1) above the required levels, with the majority of the species having Ca beyond the maximum tolerable limit. Most browse plants had sufficient K, phosphorus, magnesium, manganese, iron and Zn concentrations to meet the requirements for ruminants. Copper was deficient in many browse leaves, thus supplementation should be considered in winter. We conclude that such knowledge is essential for sustainable use of browses as mineral supplements, especially during critical periods when climatic conditions limit the feed value of grasses.