摘要:

AbstractLignocellulosic agricultural wastes were impregnated with small amounts of hydrochloric and sulphuric acids and aged under varying conditions of temperature and time. Hydrochloric acid was added as vapour and sulphuric acid as a dilute aqueous solution and the fibres subsequently air‐dried. The acid‐aged fibres became more digestible to rumen fluid (in vitro) and to cellulase, with improvements up to four‐fold (for 1.1% hydrochloric acid in oat hulls). The increases in rumen fluid digestibility were always associated with increases in water‐solubility. The effects are attributed to acid hydrolysis, especially of hemicelluloses and perhaps to some extent of lignin–carbohydrate linkages. The procedures may have some potential for low‐cost, small scale exploitation in upgrading lignocellulosic agricultural wastes for ca

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351002

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractFrom previous observations concerned with the qualitative and quantitative evolution of protein groups in developing maize (Zea maysL.) grain, it may be deduced that the amount per grain of any amino acid incorporated into the proteins is linearly related to the amount of true protein in the grain. In this study, such a linear relationship is characterised quantitatively from experimental data by regressing the individual amino acid against the total protein accumulated in the developing grain of both normal (+) andopaque‐2 (o2) maize. The linear least squares regression on total nitrogen content in the grain is also used for specifying the quantitative variations of any free and protein‐incorporated amino acid in the grain. The slope Bjof the regression line represents the relative rate of accumulation of amino acid (j) in grain protein (or nitrogen) and its limiting content in protein (or nitrogen) of a grain which accumulates a large amount of it. Bj, which is compared to the amount of amino acid (j) present in the protein of immature grains, or of mature endosperm, or germ, is close to the amount of amino acid (j) present in the protein of mature endosperm. The same holds for the Bjvalue determined fromopaque‐2 maize and which differs from the amount of Bjdetermined using the normal variety for many amino acids. Using experimental data reported in the literature, a linear relationship has also been found in describing quantitative variations of amino acid in the developing grain of normal and Hiproly b

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351003

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe use of gel‐forming synthetic polymers as aids to water retention in sandy soils is an important development to assist plant growth in arid regions. However, the water storage properties of these soil conditioners are significantly affected by the nature and concentrations of dissolved salts in irrigation waters. Moreover, the salt response of products in the three main chemical families—starch copolymers, polyvinylalcohols and polyacrylamides—is very different, emphasising the importance of detailed assays in selecting a product for a particular set of environmental condi

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351004

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractPerennial ryegrass (Lolium perenneL.) was grown in pots on 21 UK soils, both with and without fertiliser N. The fertiliser N was applied in six equal applications of15N‐labelled ammonium nitrate, each at the rate of 120 mg N per pot. The first application was mixed thoroughly with the soil, while subsequent applications were made in solution to the soil surface, after each of the first five of the six harvests of herbage. In the absence of fertiliser N, the proportion of the total soil N taken up by the plants, including stubble and roots at the sixth harvest, varied between 1.5 and 4.0%. In the presence of fertiliser N, the proportion varied between 2.1 and 4.7%. The apparent recovery of the fertiliser N was calculated from the difference between the amounts of N in the plants that received fertiliser N and in those that did not, expressed as a percentage of the amount applied. The actual recovery of the applied fertiliser N was determined by analysis of the plant material for15N. With all soils at the first harvest, the apparent recovery was greater than the actual recovery. When calculated over all six harvests, apparent recovery of the total amount of fertiliser N was generally close to the actual recovery. This difference from the first harvest probably reflected (i) a reduction in the extent of turnover between fertiliser N and soil N when the fertiliser N was applied to the surface and (ii) a virtually complete uptake of available soil N by the end of the experiment, in both the absence and presence of fertiliser N. Differences between the 21 soils in actual recovery were not closely related, either positively or negatively, to a range of measured soil properties. A mean of 17.2% of the labelled fertiliser N was retained in the soil (excluding visible roots) at the end of the experiment. The lowest retention (6.2%) occurred with the soil which had the lowest contents of organic matter and silt plus clay but, with the other soils, the extent of retention varied only between 14.7 and 22.0% of that applied, and was not closely related to contents of total organic matter or macro‐organic matter, or to the C:N ratio of the whole soil or the macro‐organic m

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351005

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractProtein quality indices (PER, nitrogen balance, digestibilities of protein, methionine and lysine) were obtained for two allegedly poor quality fish meals of unknown origin and for two Norwegian capelin meals. The former two contained 40 and 50%, the latter two, 6 and 12% of their methionine in the form of methionine sulphoxide. A high sulphoxide content was associated with poor protein quality. Thus, autoxidation during production or storage may affect fish meal protein differently from oxidation with hydrogen peroxide in the laboratory. Methionine supplementation did not improve the PER‐values of any of the meals. This indicates that methionine was probably not the first limiting amino acid for protein utilisation in these meals for the young ra

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351006

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe lipids and lipoproteins of intestinal lymph in the sheep make a contribution to the corresponding fractions in plasma and thence affect lipid compositions in other tissues. As a first step towards assessing this contribution, the lipoproteins of intestinal lymph, peripheral (popliteal lymph) and plasma have been isolated for compositional studies. Popliteal lymph and the plasma were similar in the distributions of lipids among the major lipoprotein fractions with high‐density lipoproteins accounting for just over half of the total lipid present. In intestinal lymph, 80 per cent of the total lipid was associated with the very low‐density lipoprotein fraction. Whereas triacylglycerols comprised the principal lipid component of the very low‐density lipoprotein and low‐density lipoprotein fractions of the intestinal lymph and were present in the high‐density lipoprotein fraction, they were present in essence only in the very low‐density lipoprotein fraction of popliteal lymph and plasma, where high concentrations of cholesteryl esters and phospholipids were found in all the lipoprotein fractions. The fatty acid compositions of each lipid class were also determined. The most distinctive feature of the results was the distribution of the essential fatty acid, linoleic acid, among the lipid components. In all lipid classes in each of the body fluids, the concentration of this component was highest in the high‐density lipoproteins and lowest in the very low‐density lipoproteins. Higher concentrations tended to be present in the triacylglycerols and phosphatidylcholine fractions of intestinal lymph than of plasma and popliteal lymph, but the opposite was true of the cholesteryl esters. The results are discussed in terms of the sources of the linoleic acid in the lipids of intestinal lymph of r

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351007

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of drought and irrigation on the yield and fertiliser nitrogen uptake by cut permanent grass swards was investigated using lysimeters containing monoliths (80 cm diam., 135 cm deep) of two soil types (Salop series, clay loam and Bromyard series, silt loam). Over the five summers 1977–81 swards were treated with four dressings of calcium nitrate at rates of 0 and 100 kg N ha−1after each cut; in the first year, the nitrogen was labelled with15N. Rainfall equivalent to the long‐term average gave mean yields of 12.9 t dry matter ha−1for Salop and 14.3 t dry matter ha−1for Bromyard. Irrigation (to 120% of average summer rainfall) gave a non‐significant increase of 8–9% in herbage yield on both soils. When the average rainfall distribution was modified to create periods of drought for 4 weeks duration immediately before each cut and fertiliser application, yields were significantly depressed, by 12% on Salop soil and 20% on Bromyard soil. Adjustment of the drought so that cutting and nitrogen application fell mid‐way in the dry period resulted in only a small non‐significant depression of yield on both soils (yield 95–96% of average rainfall treatment). The recovery of applied15N labelled fertiliser in herbage during the first year of the experiment was in the range 45–47% for the Salop soil and 39–52% for the Bromyard soil. In the Salop soil the recovery of the labelled nitrogen was not significantly affected by imposition of drought conditions or by irrigation. However, in the Bromyard soil the drought treatment resulted in a significant reduction in the recovery of fertiliser nitrogen to 79% of that of the average rainfall treatment and irrigation increased the recovery to 106%. The contrasting results from the two soils was due to the imposed drought treatments which were more effective in creating differing soil water status in the Bromyard soil. This was due to its good drainage and lower water holding capacity. On both soils, fertiliser nitrogen constituted 53–60% of the total nitrogen content of the herbage. This experiment indicates that on clay soils with poor drainage status, the pattern of rainfall distribution has relatively little impact on the productivity of the sward and its utilisation of fertiliser nitrogen. On freely‐draining soils, however, heavy rainfall after drought following cutting and nitrogen application can substantially depre

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351008

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractNitrogen losses were measured in water draining from cut permanent grass swards growing in monolith lysimeters containing clay loam (Salop series) or silt loam (Bromyard series) soils. The swards were cut at 6‐week intervals during the summer and were fertilised with calcium nitrate at rates of 0 and 400 kg N ha−1in each of five successive years (1977–81); in the first year the fertiliser was labelled with15N. Four differing rainfall regimes were imposed from spring to autumn in each year. Mean annual losses of nitrogen by leaching from unfertilised swards were 3.8 kg N ha−1with mean nitrate‐N concentrations in the water of about 1 mg N litre−1. In fertilised lysimeters where rainfall distribution was that of the long‐term average the mean annual total nitrogen losses were 41 kg N ha−1in the Salop soil and 15 kg N ha−1for the Bromyard soil; mean nitrate‐N concentrations were 11.6 mg N litre−1and 5.1 mg N litre−1, respectively. Losses of nitrogen and nitrate concentrations were similar to these quantities when irrigation increased the rainfall total to 120% of average. Where a drought was imposed for 2 weeks before and after each cut, mean nitrate‐N concentrations increased to 20.3 mg N litre−1on Salop soil and 13.1 mg N litre−1on Bromyard soils; total annual nitrogen losses were 74 kg N ha and 33 kg N ha−1, respectively. The largest losses were recorded when the drought period extended for four weeks before each cut and mean nitrate‐N concentrations increases to 28.8 mg N litre−1on Salop soil and 34 mg N litre−1on Bromyard soil, with total annual nitrogen losses of 104 kg N ha−1and 109 kg N ha−1, respectively. Losses of nitrogen derived from the fertiliser labelled with15N were 7.3–8.4% of that applied in the Salop soil (29–33 kg N ha−1), with little effect by the differing rainfall distributions. On the Bromyard soil, losses were 3.7% (14 kg N ha−1) of the applied fertiliser in lysimeters not subjected to droughts. When the period of the drought extended before and after each cut, losses were 8.2% (32 kg N ha−1) and increased to 17.9% (70 kg N ha−1) when the drought period occurred entirely before each cut. Fertiliser nitrogen contributed 48–69% of the total nitro

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351009

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe nutritional quality of the cormels ofColocasia esculenta(L.) Schott cultivar ‘Guavir’ was determined chemically and biologically in feeding experiments with weanling rats. The contents of starch and unavailable carbohydrates (cellulose, hemicellulose and pectin) were 54 and 15% of the dry matter respectively. Lipid accounted for less than 1% of the dry matter. Palmitic, oleic and linoleic acids were the main fatty acids in the lipids, with linoleic acid predominating. The content and fatty acid composition of the individual lipids was examined. Crude protein amounted to 10.4% of the dry matter. This protein was low in the sulphurcontaining amino acids and tryptophan, but contained adequate levels of the other essential amino acids. Diets containing raw cormel meal gave severely depressed net protein utilisation (NPU) and total nitrogen and carbohydrate digestibility when fedad libitumto weanling rats. Both NPU and nitrogen and carbohydrate digestibility improved when the cormel meal was cooked prior to inclusion in the diets but such diets still did not support growth in weanling r

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351010

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractPectinesterase (PE) was partially purified from papaya pulp, and its biochemical properties were studied. The enzyme was eluted in a single peak after DEAE‐cellulose and Sephadex G‐100 chromatography. The PE had a molecular weight of 53000 and showed an optimum pH of 8.0. Its activity was dependent on an NaCl concentration of 0.2M. The enzyme was heat stable: approximately 80% of the original activity remained after 60 min of heating at 50°C but completely inactivated by incubation at 80°C for 1 min. The activity was linear with time and protein concentration. The maximum reaction in 3 min was found at 60°C and the initial rate increased 9‐fold from 20 to 60°C. The estimated Kmwas 0.12g litre−1with citrus pectin as the substrate. The kinetic study revealed that polygalactur‐onic acid is a competitive inhibitor, and a Kivalue of 0.07 g litre−1was determined. On the basis of this study, papaya PE properties resembled those of pectinesterase fro

ISSN:0022-5142    

DOI:10.1002/jsfa.2740351011

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY