Iron accumulation in tobacco plants expressing soyabean ferritin gene

High iron-content transgenic tobacco plants have been produced by transfer via Agrobacterium tumefaciens of soyabean ferritin cDNA under the control of a CaMV 35S promoter. Immunoblot analysis of protein from transgenic tobacco plants suggested mature ferritin subunits are produced by cleavage of transit peptides. The expressed ferritin was observed in the tissues of leaves and stems. The maximal iron content of transformant leaves was approximately 30% higher than leaves from non-transformants. The increased iron content of each transformant was correlated with increases in ferritin content. These results demonstrate the potential of breeding high iron content crops by introduction of the ferritin gene     

Nitrogen release from roots of alfalfa and soybean grown in sand culture

An enclosed root chamber containing sterile sand medium was used to study net nitrogen (N) release from actively growing root systems of ‘Saranac’ alfalfa (Medicago sativa L.) and ‘Fiskeby V’ soybean (Glycine max L. Merr.). Plants were inoculated with a rhizobial strain appropriate to each host, irrigated with N-free nutrient solution, and grown either to 85 or to 173 d after germination (alfalfa) or to physiological maturity (soybean). Alfalfa released 4.5% of symbiotically-fixed plant N into the root zone over its growth period; soybean released 10.4% of plant N. Root zone leachates were analyzed for total N and for amino acid and ammonium content. Significant ammonium-N release occurred from the alfalfa but not the soybean root system; little amino-N was released by root systems of either species. Shoot harvest and water deficit caused increased release of N from alfalfa roots. The results provide evidence that alfalfa and soybean released significant proportions of their N into the root zone, and indicate that while substantial ammonium-N was released from alfalfa roots, passive leakage of amino-N was not a primary mechanism for N release from root systems of either species. Cooperative investigation of USDA-ARS and the Minnesota Agric. Exp. Stn. (Scientific J. Series No. 16048). This research was supported in part by a Graduate School Fellowship to LSB from the Univ. of Minnesota.     

进口转基因抗草甘膦油菜籽和大豆中CP4—EPSPS基因的检测比较研究

由于国际上对转基因产品的安全性存在的较大争议,因此对没有加施标签予以声明的情况下大量进入中国市场的转基因产品进行检测就显得十分迫切且意义重大。本研究以进口转基因抗草甘膦油菜籽和大豆为材料,通过比较分析外源的CP4－EPSPS基因的核苷酸序列和表达的氨基酸序列,设计出两对不同的引物,采用PCR方法分别对转基因油菜籽和大豆中外源的CP4－EPSPS基因进行了检测。     

Prediction of digestible and metabolisable energy in soybean meals produced from soybeans of different origins fed to growing pigs

The objective of this experiment was to determine the digestible energy (DE) and metabolisable energy (ME) in 22 sources of soybean meal (SBM) produced from soybeans from different countries and subsequently to establish equations for predicting the DE and ME in SBM based on their chemical composition. The 22 sources of SBM were all processed in Chinese crushing plants, but the soybeans used originated from China (n = 6), the US (n = 6), Brazil (n = 7) or Argentina (n = 3). The basal diet was a corn-based diet and 22 additional diets were formulated by mixing corn and 24.3% of each source of SBM. The average DE and ME in SBM from China, the US, Brazil and Argentina were 15.73, 15.93, 15.64 and 15.90 MJ/kg and 15.10, 15.31, 14.97 and 15.42 MJ/kg, respectively, and no differences among countries were observed. From a stepwise regression analysis, a series of DE and ME prediction equations were generated. The best-fit equations for SBM were DE = 38.44–0.43 crude fibre ?0.98 gross energy +0.11 acid detergent fibre (R² = 0.67, p < 0.01) and ME = 2.74 + 0.97 DE ?0.06 crude protein (R² = 0.79, p < 0.01). In conclusion, there were no differences in the DE and ME of SBM among the different soybean sources used in this experiment. The DE and ME of SBM of different origin can be predicted based on their chemical composition when fed to growing pigs.     

Effect of substituents at the 9-position on cytokinin activity

The preparation and properties of cytokinins substituted in the 9-position by methoxymethyl, propyl and cyclohexyl are described. Each is less active in the soybean and tobacco tests than the unsubstituted cytokinin from which they were derived.     

Effects of diets differing in protein source and technical treatment on digestibility,performance and visceral and biochemical parameters of fattening pigs

The aim of the experiment on 100 cross-bred barrows was to compare commercial diets for fattening pigs based on either soya bean meal (SBM) imported from non-European countries with diets based on a mixture of locally produced rape seed meal, distillers’ dried grains with solubles and soya beans as main protein sources. In addition, these both types of diets were processed by two different technical feed treatments, i.e. coarse grinding without hydrothermal treatment or fine grinding and pelleting. With only few exceptions, nutrients of the diet without SBM were more digestible (p < 0.05) resulting in a higher metabolisable energy (ME) content. Fine grinding and pelleting increased also the ME content and the nutrient digestibility with the exception of crude fibre. Higher feed intake of animals that fed diets without SBM (p < 0.01) resulted in higher average daily gain (p < 0.01). However feeding this diet, the higher digestibility was not reflected in a decreased feed-to-gain ratio (FGR), but fine grinding and pelleting reduced FGR (p < 0.001). A higher pH value and a lower DM content of caecal chymus were detected in animals that received coarsely ground feed (p < 0.05). Animals that fed finely ground and pelleted feed had higher slaughter and relative liver weights and higher blood cholesterol concentrations (p = 0.040). The urea concentrations of blood were lower (p = 0.019) after feeding diets without SBM. In conclusion, SBM imported from non-European countries can be replaced by alternative local protein sources without compromising digestibility or performances of animals. Although fine grinding and thermal treatment particularly seemed to be advantageous for digestibility and performance, the possible risk of development of stomach lesions should be considered.     

Role of biological nitrogen fixation in legume based cropping systems; a case study of West Africa farming systems

Nitrogen (N) has been gradually depleted from West African soils and now poses serious threats to food production. Many ways of increasing N supply (e.g. judicious use of inorganic fertilizers and nitrogen-fixing plants) have been tried in West African farming systems. Herbaceous and woody legumes commonly contribute 40–70 kg N ha^–1 season. This represents about 30% of the total N applied as residues. Nevertheless and despite repeated demonstrations of the usefulness of green manures in enhancing soil fertility, their practices and adoption are still limited. Promiscuous soyabeans are being used to develop sustainable cropping systems in the moist savannah. Reliable estimates of N₂ fixed by soyabeans and their residual N benefits to subsequent cereal crops in the savannah zone of southern Guinea have only infrequently been made. The actual amounts measured varied between 38 and 126 kg N ha^–1 assuming that only seeds of soyabeans are removed from the plots, the net N accrual of soil nitrogen ranges between minus 8 kg N ha^–1 and plus 47 kg N ha^–1 depending on the soyabean cultivar. Residual soyabean N values of 10–24 kg N ha^–1 (14–36% of the total N in maize) were obtained in a soyabean-maize rotation. Although cereal yields following legume cultivation have been attributed to greater N accumulation, our data show that the relative increase in maize N was smaller than the relative increase in dry-matter yield. Hence, the increased yields of maize following soybeans are not entirely due to the carry-over of N from soyabean residues (as well as to conservation of soil N) but to other rotational effects as well. It is thus clear that the Nbenefit of grain legumes to non-legumes is small compared to the level of N fertilizer use in more intensive cereal production systems but is nevertheless significant in the context of the low amounts of input in subsistence farming.     

Encapsulation of soybean meal with fats enriched in palmitic and stearic acids: effects on rumen-undegraded protein and in vitro intestinal digestibility

Fat coating of soybean meal (SBM) can reduce its protein degradability in the rumen, but the encapsulation of SBM with palmitic (PA) and stearic acids (SA) has not yet been investigated, despite both fatty acids are common energy sources in dairy cow diets. This study aimed to evaluate the effects of applying a novel method, using either 400 or 500 g fat/kg (treatments FL40 and FL50, respectively), which was enriched in PA and SA at different ratios (100:0, 75:25, 50:50, 25:75 and 0:100), on physical and chemical characteristics, ruminal degradability, solubility and in vitro intestinal protein digestibility (IVIPD) of the obtained products. Encapsulation of SBM in fat resulted in greater mean particle size and lower bulk density and protein solubility than unprotected SBM (USBM). Treatment FL50 resulted in increased (p < 0.01) rumen-undegraded protein (RUP) compared to USBM. There were no differences in RUP of SBM when different PA: SA ratios were used. The mean RUP content of treatments FL40 and FL50 (306 and 349 g/kg, respectively) was greater compared to USBM (262 g/kg, p < 0.05), but lower than that for a standard heat-treated SBM (431 g/kg). Values of IVIPD did not differ among SBM, heat-treated SBM and FL40 and FL50 samples, all being greater than 97.8%. In conclusion, encapsulation of SBM with fats enriched in PA and SA proved to be effective in reducing protein solubility and increasing RUP without depressing protein digestibility in the intestine. For validation of the method, in vivo research to investigate the effects of these products on the production of dairy cows is warranted.     

A review of processing of feed ingredients to enhance diet digestibility in finfish

Replacement of fish meal with plant proteins in aquaculture diets presents several problems. Firstly, aquaculture diets, particularly diets for carnivorous fish species, are nutrient dense and may contain up to 450 g crude protein (CP)/kg. Such diets preclude the use of ingredients with only moderate CP content, such as pulses including peas and faba beans or oilseed meals including canola/rapeseed meal and flax. Secondly, virtually all crops contain heat-labile and heat-stable secondary compounds including protease inhibitors, tannins, lectins, phytate, dietary fibre and starch. Removal of heat-labile secondary compounds may be accomplished by extrusion or other heat treatment. However, elimination of heat-stable secondary compounds, and increasing the nutrient concentration of diets, requires fractionation of crops. Fractionation technologies range from low technology processes such as dehulling to medium technologies such as air classification to sophisticated technologies such as aqueous and solvent protein purification. Studies on the nutritional value of processed plant proteins in various fish species have consistently shown improved digestibility and growth compared to feeding unprocessed ingredients. This review examines effects of processing technologies on nutritional properties of soybean meal, canola meal, peas, lupins and flax in aquaculture diets.