摘要:

AbstractThe rumen fermentation pattern was studied in mature, dry non‐pregnant Chios ewes and Damascus goats. They were fed one of five roughages: barley, lucerne or sudex hay, barley straw and acacia leaves and twigs alone and in combination with concentrates (1:1 ratio). Goats had significantly lower pH values when barley hay+ concentrate or sudex hay were fed. The level of ruminal NH3‐N did not differ between species, but it was affected by source and level of dietary protein. The tungstic acid precipitable protein concentration (g litre−1) in rumen liquor was generally higher in goats than in ewes (6.1 versus 4.9). The molar proportions of individual VFA and total VFA concentration were significantly affected by diet but not by sp

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341202

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractSamples of wheat and barley straw, milled through a 1 mm sieve, were ball milled to<0.25 mm as a representative physical treatment, or delignified by the acidchlorite procedure as a representative chemical treatment. The original and treated samples were examined using in‐vitro digestion systems based on rumen liquor‐pepsin and pepsin‐cellulase. The digestibility was determined as well as the extent of digestion of the cellulose, hemicelluloses and lignin.The rumen liquor‐pepsin system was able to digest a greater proportion of the original and treated straws than the pepsin‐cellulase system while ball milling improved the digestibility more than delignification, irrespective of the digestion system. Core lignin was not digested by either system. Ball milling improved the digestibility of the cellulose fraction to a greater extent than the hemicellulose fraction, whereas delignification had a greater effect on hemicellulose digestion than on cellulose digestion. There were also differences in the rate of removal of the different sugar residues present in the hemicellulose

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341203

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe distribution of alkali labile substituents of the neutral sugar components of hemicellulose in unfractionated cell walls of early‐ and late‐cut perennial ryegrass, wheat and barley straw, and white clover, before and after extended incubation in the rumen, was determined by a modified methylation technique. Xylose residues were found to be extensively substituted, with 50% of residues in the Gramineae and 75% in white clover carrying substituent groups onO‐2 and/orO‐3. Acetyl groups could account for 50–70% of substitutions, the remainder being to unknown cell wall components. The distribution of alkali‐labile substituents of xylose was the same in the original plant material as in residues recovered from the rumen, and was not affected by delignification under conditions which preserved the acetyl content of cell walls. Arabinose residues were heavily substituted atO‐5, with 40–60 % of residues from the Gramineae, but only 10% of residues from the white clover, carrying substituent groups at this site. Linkages toO‐5 of arabinose were preserved during digestion and accumulated in residues recovered from the rumen. In all plants examined, the extent ofO‐5 substitution strongly correlated with the proportion of total phenolics (r=0.844) and total phenolics minus phenolic acids (r=0.779) present. The correlation was improved when restricted to the Gramineae (r=0.879 and 0.881 respectively). Within the Gramineae, the increase in the extent of substitution toO‐5 of arabinose correlated well with the increase in the proportion of total material in digested residues (r=0.899). As correlations were retained or improved when values for phenolic acids were subtracted from total phenolics, and as the proportion of phenolic acids decreased during digestion, it is suggested that linkages toO‐5 of arabinose represent one form of lignin‐carbohydrate bonding. The importance of such linkages to the control of polysaccharide degradation and the effect of their cleavage by alka

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341204

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe technique of methylation analysis for the location of glycosidic linkages in cell wall polysaccharides was applied directly (after dry milling in liquid nitrogen) to whole wheat and barley straws, cell wall preparations from early‐ and late‐cut perennial ryegrass and white clover, and their extensively degraded residues recovered from the rumen. The addition of an internal standard, methyl‐β‐D‐allo‐pyranose, to milled samples enabled the recovery of partially‐methylated sugars to be quantified, and the recovery of parent sugars from methylated material to be compared with values obtained by direct estimation of monosaccharides by the alditol acetate method. Recovery of sugars from methylated samples was generally higher than that predicted by the alditol acetate method, particularly from digested residues.All four samples of Gramineae showed similar proportions of glycosidic linkages in which (1 →4)‐linked xylose and glucose units accounted for more than 80% of total identified partially‐methylated sugars. The proportions of glycosidic linkages found in digested residues of straws were essentially the same as those found in the parent material. In residues of the more digestible ryegrass there was a two‐ to three‐fold increase in (1→4)‐linked xylose units without branch points at theO‐2/O‐3 positions, the proportions of these branch points being substantially reduced. A corresponding reduction in the proportion of (1→2)‐, (1→3)‐and terminally‐linked arabinose units was also found. The proportion of both (1→4)‐ and (1→3)‐linked glucose units were also reduced in digested residues. These changes were greater in the early‐cut than in the late‐cut sample. White clover differed from the Gramineae in a number of respects. Galactose units predominantly in the form of (1→4)‐, (1→6)‐ and terminally‐linked units, were the major non‐cellulosic sugars present. The proportion of all forms of galactose was reduced in digested residues, but (1→6)‐linked units appeared more resistant to degradation than (1→4)‐linked units. Like ryegrass, the proportion of xylose units increased in digested residues from clover, while the proportion of glucose decreased. The proportion of (1→4)‐linked mannose units, initially present at

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341205

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThis study was carried out to compare the time course of laying down seed storage protein in three legumesviz:cowpea (Vigna unquiculata), mung bean (Phaseolus aureus) and soya bean (Glycine max) planted in two replications. Pods were harvested periodically during seed maturation and studied for changes in fresh and dry weights, total sulphur, total nitrogen and protein content. At early stages of development crude protein formed about one‐third of dry weight in the legumes but decreased to about one‐quarter at maturity. The total sulphur which formed a substantial amount of the sulphur amino‐acids in mature seeds did not change much in mung bean and cowpea but increased by about 24% from 20 to 69 days after flowering (DAF) in soya bean. Storage protein accumulation was very rapid between 10 and 14 DAF (10.4% day−1) in mung bean, 7 and 14 DAF (12.9% day−1) in cowpea and between 20 and 30 DAF (9.4 day−1) in soya bean. Thereafter, protein accumulation declined slightly and gradually approached zero at time of seed maturity. The sulphur‐to‐nitrogen ratios gradually increased with maximum values in the mature seeds.Although seed protein content and quality (on S/N ratio basis) were highest in soya bean, accumulation of storage protein seemed to be faster in cowpea than mung bean and soya bean during

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341206

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractEighty laying hens (40 Hisex white, 40 Hisex brown) were given, for ten 28‐day periods, a control diet and four experimental diets in which the relationship between Na, K and Cl (Na+KCl) expressed as mEq kg−1diet was elevated by adding increasing amounts of NaHCO3and K2CO3. Increasing the (Na+KCl) mEq kg−1diet had no significant effect on any of the parameters measured but the breed x diet interaction significantly affected mean e

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341207

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractIn each of two experiments, 600 male broiler chicks (Ross 1) were randomised into 24 groups each containing 25 birds. From the age of seven days they were given one of six experimental diets. These were a control diet having ground wheat as the main cereal source and five other diets in which mainly the wheat was replaced by increasing amounts (100, 200, 300, 400, 500 g kg−1diet) of dried cassava root meal. Neither body weight nor food intake were significantly affected in either experiment by the inclusion of dried cassava root meal at levels up to 500 g kg−1. Food conversion efficiency was unaffected by dietary treatment except in experiment 1 after 4 weeks, when the diet with 100 g cassava meal kg−1resulted in a better food conversion efficiency than in the case of the other dietary treatments. The carcass and abdominal fat weights and the chemical composition of the carcasses were unaffected by dietary treatment. In the caecal contents the proportion of acetic acid was increased and that of propionic and valeric acids reduced by the inclusion of dried cassava root meal. The moisture content of the litter was not significantly affected by the presence of cassava root meal although the litter became wet and sticky in the groups given the two highest levels of cassava root meal in Experiment 1. For this reason, the maximum recommended level of inclusion of dried cassava root meal in broiler diets i

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341208

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractSome phosphate soil tests (P‐tests) are evaluated for their suitability to assess the phosphate status (P‐status) of contrasting soils. A P‐test at best only provides a relative estimate of the soil P‐status, which may be thought of as the ability of a soil to release P either to a crop, or more specifically to a given plant root for a given period under optimum conditions with respect to all other growth factors. A P‐test gives no direct information on the crop response to added P.The P‐tests were evaluated on the basis of data from 29 published papers where the anion exchange resin method was among the P‐tests used, and where plant P‐uptake in pot experiments had been used as the evaluation basis.The evaluations ranked the P‐tests in three groups: best group: anion‐exchange resin method, intermediate group: water, and sodium bicarbonate methods, worst group: all ‘acid’ methods: acetate buffer, lactate buffer, citric acid, Bray‐1, T

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341209

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA consumer survey of the quality of six samples of apples (Cox's Orange Pippin and Suntan stored at 4°C in 2% O2,<1% CO2, and Cox's Orange Pippin stored in 1% O2,<1% CO2, all three subsequently held for 10 days in air at 4°C or 17°C showed them to be equally acceptable, but for different reasons. Suntan had a poor aroma but a more acceptable appearance and overall flavour (by virtue of being sharper) than Cox's Orange Pippin, irrespective of storage conditions. Fruit stored at the lower O2level and held post‐storage at the lower temperature was less sweet and sharp, but had a crisper and juicier texture than fruit stored at the higher O2concentrations and post‐storage tempe

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341210

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA total of 23 cultivars of apricot, cherry, nectarine, peach and plum available on the retail market in Sydney, Australia during the summer of 1981–82 were analysed and data are presented for water, protein, fat, sugars (fructose, glucose and sucrose), starch, dietary fibre, organic acids (malic, citric, quinic, shikimic and oxalic acids), ash, sodium, potassium, calcium, magnesium, iron, zinc, vitamin C, α‐carotene, β‐carotene, thiamin, riboflavin niacin, soluble solids, respiration rate and titratable acidity. Edible weight and energy were calculated. Data were compared with various national food composition

ISSN:0022-5142    

DOI:10.1002/jsfa.2740341211

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY