bluuebunny/crossref_metadata_2025 huggingface dataset:
Rumen fermentation of fresh herbage
Authors: Williams V. J. , Christian K. R.
Published: March 2009

1. On twelve occasions covering a complete seasonal cycle rumen mierobial end-product concentrations were measured in a group of sheep allowed to graze a pasture for 1 hr. Considerable differences were obtained in the rises in total volatile fatty acid and ammonia after feeding, in average rumen protein nitrogen and in free mierobial count.

2. Seven samples of fresh herbage wfere fed to groups of sheep in pens at different levels of intake. Increase in feed intake with five of the herbages produced significant increases in rumen ammonia and total volatile fatty acid and with one herbage there was a significant increase in protein nitrogen. Free mierobial count was measured after feeding three herbages and was found to be independent of intake level.
The value of liquid digested sewage sludge. III. The results of an experiment on barley
Authors: Coker E. G.
Published: March 2009

In a trial laid out to compare the effects of liquid digested sludge with equivalent nitrogen and phosphate fertilizers as ‘Nitra-shell’ and superphosphate, growth data, and data of grain and straw yield were obtained.

Liquid digested sludge increased the dry weight and shoot number at the ‘tillering’ stage, and dry weight and ear number at the flowering stage, more than equivalent fertilizer.

By 13 May, sludge-treated plants had absorbed more nitrogen than fertilizer-treated plants. By 19 June this was reversed for the sludge-treated plants had then absorbed 81% of the nitrogen absorbed by fertilizer-treated plants; ripe grain from sludge plots had a lower nitrogen percentage than grain from fertilizer plots.
Time of application and chemical form of potassium, phosphorus, magnesium and sodium fertilizers and effects on the growth, yield and quality of sugarbeet (Beta vulgaris)
Authors: Allison M. F. , Jaggard K. W. , Armstrong M. J.
Published: March 2009

Summary Between 1985 and 1988, 14 field experiments at different sites in the UK assessed the effect of applying P, K, Na and Mg in autumn, early spring, late spring or as a split application in both autumn and late spring on the growth, yield and processing quality of sugarbeet. Supplementary experiments compared Kaynitro and Chilean nitrate of soda. None of the treatments had any effect on plant population densities, and any differences in sugar yield could be explained by the leaching of Na. The effects on processing quality were inconsistent and unlikely to be of agronomic or economic significance. Generally, Kaynitro and Chilean nitrate of soda performed no better than the other fertilizers so it is unlikely that their extra cost would be justified. Apart from Na, the timing of nutrient application appeared to be unimportant, even on soils of low fertility. However, Na, being very mobile, was best applied in spring.
Proceedings of the Twenty-Fifth Meeting of the Agricultural Research Modellers' Group
Authors: France J.
Published: March 2009

This group, which is concerned with the applications of mathematics to agricultural science, is sponsored by the Biotechnology and Biological Sciences Research Council. It was formed in 1970, and has since met at approximately yearly intervals in London for one-day meetings. The twenty-fifth meeting of the group, chaired by Dr T. M. Addiscott of the Institute of Arable Crops Research, Rothamsted Experimental Station, was held in the Wellcome Meeting Room at the Royal Society, 6 Carlton House Terrace, London on Friday, 15 April 1994, when the following papers were read.
Variation in seasonal stocking rate and the dynamics of Lotononis bainesii in Digitaria decumbens pastures
Authors: Fujita H. , Humphreys L. R.
Published: March 2009

Pastures of Digitaria decumbens (pangola grass) previously oversown with Lotononis bainesii at Mount Cotton, south-east Queensland, Australia, were grazed by sheep for 3 years (1985–87), using a factorial combination of seasonal variations in stocking rate.

Lotononis behaved as a short-lived plant with a mean half-life of 4·2 months (range 1·6–10·3); rate of mortality was positively related to initial seedling density. The proportion of lotononis remained very low for the first 2 years of the experiment, when conditions were unsuitable for large-scale seedling regeneration, which was also limited by the hardness of the seed reserves. Subsequently, lotononis regenerated well in treatments which combined the following features: (i) light grazing (5 sheep/ha) during the main flowering period of spring-early summer, (ii) heavy short-duration grazing in mid-summer to create a ‘gap’ and (iii) medium or heavy (18 or 27 sheep/ha) grazing during late summer-autumn to reduce competition from pangola grass.

The ecological niche of lotononis and the possible use of complementary pastures are discussed.
Moisture transport under cyclic trickle irrigations in different textured soils
Authors: Pal D. , Sen H. S. , Dash N. B. , Bandyopadhyay B. K.
Published: March 2009

Moisture movement through soil under trickle irrigation was studied in the laboratory at the Central Soil Salinity Research Institute, West Bengal, in 1988/89. Using a cylindrical flow model, the finite difference technique was used to compute the 2-dimensional moisture distributions and wetting front advancements in soils with clay contents ranging from 22·1 to 51·8%. Seven-day cyclic irrigations, each day having one on-cycle (infiltration) with a constant trickle discharge of 0·3 litre/h for 12 h and one off-cycle (redistribution) for 12 h, were used with two water qualities, EC 0·15 and 0·64 S/m. Moisture distributions were measured in artificially packed soil columns 60 cm high and 56 cm in diameter. The degree of agreement between the theoretical and observed values was expressed by Relative Error Percent (REP), defined as the difference between the two, divided by the observed value and expressed as a percentage. The mean REP ranged from 0 to 30, 62·5% of the values falling in the range 0–10, 22·5% from 10 to 20, and 15% from 20 to 30, irrespective of soil texture, water salinity or the irrigation cycle used. It was concluded that the theoretical data closely matched the experimental results. The wetting front in the soil columns was defined as the minimum detectable increase in moisture (10-3 cc/cc) from the initial content, and its advancement was calculated over the entire period of on-off cycles. This model was also used to calculate, for one soil, the theoretical moisture distribution under trickle irrigation with simultaneous loss by evaporation, which is an essential component of field moisture balance.
Breed and sex differences in body composition of sheep in relation to maturity and growth rate
Authors: Gaili E. S. E.
Published: March 2009

Twenty-four lambs (equally representing males and females), born in December 1986, were obtained from each of the Najdi, Awassi and Hejazi sheep breeds kept at the Experimental Station of King Faisal University in Saudi Arabia. The lambs were reared on their dams and fed after weaning on the same diet up to slaughter at 9 months of age. Slaughter and carcass data were analysed for breed and sex differences using the degree of body maturity and growth rate as covariates. After the effects of differences in body maturity and growth rate were removed, significant breed but not sex effects were recorded in skin, feet, carcass and carcass to bone proportions. In Najdi lambs the feet and bone nproportions (g/kg empty body weight) were higher than in Awassi or Hejazi lambs, whereas Awassi lambs possessed lower carcass but higher skin proportions than the other two native breeds.

Breed but not sex affected fat distribution. Awassi lambs had higher tail but lower intermuscular fat content (g/kg total body fat) than Najdi or Hejazi lambs. Most body components were significantly related to the degree of body maturity but not to growth rate.
Experiments on the use of anhydrous ammonia for grass
Authors: Gasser J. K. R. , Blakemore Marie , Flint R. C.
Published: March 2009

A hand injector was used to inject ammonia into soils in pots in which ryegrass was subsequently grown and under grass in the field; the spacing was varied.

Injecting ammonia or applying ammonium nitrate at one point or three points in the middle of a clay-loam and a sandy-loam soil in pots did not affect the growth of grass or its uptake of N. Grass with ammonium nitrate grew slightly better than with ammonia on the sandy loam and slightly worse on the clay loam.

Best yields of dry matter and most uptake of N were obtained from grass swards having ammonia injected in lines 23 and 30 cm apart and the injection points from onequarter to one-half of the distance between rows. Increasing the distance between lines from 30 to 45 cm diminished total yield and uptake because the strip 15·2 to 22·8 cm from the line of injection grew less than grass nearer to the line of injection.

With grass grown in rows 12·1 cm apart, yields were greatest with the lines of injection perpendicular to the rows of grass and least with the ammonia injected along and into the rows. The yield of dry matter of the row with ammonia injected into it was usually less than of the adjacent row and the percentage N in the grass was usually more, so that the weight of N in the grass sometimes increased and sometimes decreased with distance from the line of injection depending on the relative changes in yield of dry matter and of percentage N.
Ovine ill-thrift in Nova Scotia:II. The production of antibiotics by fungi isolated from forest and marshland soil
Authors: Brewer D. , Taylor A. , Hoehn M. M.
Published: March 2009

Three hundred and seventy-six isolates, or about 9% of the cultures collected in 1967 and 1968 from soil of permanent pasture, that, prior to 1883, supported mixed conifer and deciduous forest, were cultivated in the laboratory. Antibiotic production was detected in 27% of the cultures. Similarly, 329 isolates, or 9% of those collected in the same period from soil of permanent pasture reclaimed from tidal marsh, were grown in the laboratory and antibiotics detected in 30%. The forest soil, because it was already known to have a denser fungal population, thus had a greater antibiotic production potential than the marshland soil. There was a small increase in the number of isolates from the forest soil that produced antibiotics when those obtained in the spring were compared to those collected in the autumn. The opposite relationship was found when the marshland isolates from the two seasons were similarly compared. The results are consistent with the hypothesis that the fungal populations of these soils are a parameter in the aetiology of the ill-thrift that is found in ruminants at Nappan, Nova Scotia.
Culture and fertilization of sheep ovarian oocytes:IV. Observations on sperm penetration in oocytes transferred to the sheep oviduct
Authors: Crosby T. F. , Ryan P. O. M. , Gordon I.
Published: March 2009

Transfer was made of 2958 sheep ovarian oocytes, cultured in growth medium for 24–30 h, to the oviducts of 142 oestrous sheep; 132 were bred and ten remained unbred. Forty-two per cent of oocytes were recovered, mainly 4–24 h after transfer; tubal flushings were examined for sperm. Evidence of a sperm within the vitellus of follicular oocytes was found in nine recipients, the earliest at 6 h 50 min after transfer. Pronucleate eggs were most frequent 9–14 h after transfer; a limited number of eggs showing normal cleavage wasrecovered.
High-level cereal diets for the growing/finishing pig:V. A comparison of finisher diets containing high levels of maize or barley with wide or narrow calorie/protein/lysine ratios when fed to give two different calorie intakes
Authors: Lawrence T. L. J.
Published: March 2009

In an incomplete block 2x2x2 factorial experiment seventy-two Large White type pigs, after having been fed individually and identically up to 120 lb (54·5 kg) live weight, were fed from that weight up to 200 lb (90·9 kg) live weight maize or barley based diets (factor 1), with each diet having either a wide or a narrow calorie/protein/lysine (CPL) ratio (factor 2). The feeding was effected in individual feeders in a Danish type piggery (with six pigs per pen) with all diets offered as wet mashes and according to scales which gave two different calorie intakes (factor 3). There were, therefore, four different diets and eight different feeding treatments.
Selection indices for rabbit improvement
Authors: Khalil M. H. , Owen J. B. , Afifi E. A.
Published: March 2009

Records on 884 litters and 3051 bunnies of the Bauscat (B) and Giza White (G) breeds were used to construct different selection indices.

A series of selection indices and subindices were constructed for both B and G does. An index or subindex based on litter size at weaning, mean bunny weight at weaning, litter size at birth and litter weight at birth could be practically applied to improve the productivity of B and G does, under local Egytian conditions. Preweaning mortality did not contribute significantly to the different selection indices and subindices. Litter weight at birth made a large contribution to the different indices and subindices constructed. Litter size at weaning contributed little in the subindices to be used to select for mean bunny weight at weaning. Mean bunny weight at weaning made a lower contribution to the subindices to be used to select for litter size at weaning. The expected genetic gain in litter size at weaning was slight in all of the selection indices and subindices constructed because of low heritability values for this trait. Considerable genetic improvement for doe productivity of the G breed might be achieved through selection for mean bunny weight at weaning.

Four selection indices and subindices were constructed for B and G rabbits. The index or subindex based on 6-week weight and 8-week weight was the best criterion for selection for the genetic improvement of 6-week weight and 12-week weight. Six- and 8-week weight contributed substantially while 12-week weight contributed little to the value of most of the selection indices and subindices constructed. The highest total genetic gain attributable to 6- and 12-week weight was obtained when the selection indices or subindices including 6-week weight and 8-week weight were used.
The response of grass for silage to sulphur application at 20 sites in Northern Ireland
Authors: Stevens R. J. , Watson Catherine J.
Published: March 2009

Twenty field site3 were selected for their potential sulphur-deficient status. The effect of sulphur at 10 kg S/ha per cut as gypsum or kieserite on the yield and composition of grass for silage given intensive fertilizer was measured at two or three cuts in 1985. Other incidental sulphur inputs in P and K fertilizers and organic manures were minimized. There were significant increases (P < 0·05) in dry-matter yield at ten harvests on five sites. At seven of the ten harvests gypsum and kieserite were equally effective, but at three harvests only kieserite gave significant yield increases. The drymatter yield increases occurred at all three cuts.

Using soil analyses to predict sulphur-deficient sites had limited success. The conclusions from this study were that soils with extractable sulphate values < 10 mg S/l had adequate reserves for three-cut silage while soils with values > 10 mg S/l had a 1 in 3 chance of being sulphur deficient. Using plant analyses to diagnose sulphur-deficient herbage had also limited success. In this study herbage with an N/S ratio > 14 was sulphur deficient while herbage with a ratio > 12 had a 1 in 2 chance of being deficient.

The proportion of sulphur responsive sites in this study is an overestimate for Northern Ireland as a whole. Most soils in this country have higher clay and organicmatter contents than the field sites. The application of organic manures in normal agricultural practice is likely to be an important source of sulphur to grass for cutting.
The amylase activity of 14 species of entodiniomorphid protozoa and the distribution of amylase in rumen digesta fractions of sheep containing no protozoa or one of seven different protozoal populations
Authors: Coleman G. S.
Published: March 2009

The amylolytic activity of the cytoplasmic fraction prepared from 14 single species of rumen ciliate protozoa and two natural mixed populations has been determined using five different assays. All the protozoa contained an a-amylase and the major product of amylose digestion was maltose. The highest activities were found inEremoplastron bovis, Diploplastron affine, Ophryoscolex caudatus and Polyplastron multivesiculatumgrown in vitro on grass and wholemeal flour and the lowest inOstracodinium obtusum bilobumandDiplodinium pentacanthumunder all growth conditions and in culturedEntodinium bursaandE. caudatum. The maximum activities depended on the substrate and withEremoplastronbovis varied from 2·3 (with starch grains) to 48·8 (with amylose) μtmol maltose produced/mg protein per h.

The distribution of amylase between various rumen fractions has been determined at three times after feeding in sheep containing no ciliate protozoa or seven different protozoal populations. A method to give maximal release of the enzyme from mixed rumen bacteria was devised and three different assay methods were compared. The total rumen amylase varied by up to 2·6 times and was highest in animals that contained onlyEntodinium caudatumor natural A- or B-type populations. The distribution of amylase activity between rumen fractions varied considerably with the various protozoal populations, that in the protozoal cytoplasm being highest in animals containingEpidinium ecaudatum caudatum(46–53%) and the natural A- and B-type populations (35–57 %) and lowest in the animals containing no protozoa (3–11 %) or onlyOstra-codinium obtusum bilobum(6–21%). The reverse was true for the activity in the bacterial fraction which contained little activity in animals with natural A- and B-type populations and over 58% of the total activity in an animal containing onlyEntodinium caudatum. The lowest activities in all fractions were obtained 1·5 h after feeding. Comparatively little activity was found in the plant debris or clarified rumen fluid fractions from any animal. Using results obtained previously the ratios of carboxymethylcellulase to amylase activities have been calculated and shown to be highest in the protozoal cyto-plasmic fraction ofDiplodinium pentacanthumandOstracodinium obtusum bilobumandlowest in Entodiniumspp.,Diploplastron affineandEremoplastron bovis.
Effects on egg production and quality of supplementing the diet of hens laying brown eggs with blood meal and magnesium chloride
Authors: Karunajeewa H. , Abu-Serewa S. , Tham S. H. , Harris P. A.
Published: March 2009

In a 2 × 4 factorial experiment, the laying performance of hens given diets with or without blood meal and four concentrations (0, 5·71, 11·43 and 17·14 g/kg) of added magnesium chloride was measured for 280 days. The inclusion of 50 g/kg blood meal in the laying diet reduced the rate of laying (P < 0·05), egg weight (P < 0·01), egg output (P < 0·01), food intake (P < 0·01), body weight gain (P < 0·01) and body weight at 457 days (P < 0·05). It increased the height of albumen (P < 0·05), Haugh unit score (P < 0·01) and shell colour intensity (P < 0·05) of fresh eggs. The inclusion of increasing dietary concentrations of magnesium chloride reduced (P < 0·01) the specific gravity of eggs but had no significant effect on any of the other egg quality or production characteristics. The dietary treatments had no significant effect on Haugh units of stored eggs.
Effects of nitrogen application on growth characteristics of signal grass (Brachiaria decumbens)
Authors: Okeagu M. U. , Asiribo O. E. , Akinola J. O.
Published: March 2009

Signal grass (Brachiaria decumbens Stapf.) given 100, 200, 300 and 400 kg N/ha and protected from defoliation by growing in cages was evaluated for tiller height, tiller density and dry matter (DM) yield in 1979 and 1980.

Nitrogen rate had highly significant linear effects on tiller height and density and DM yield of the grass at each age of pasture regrowth and at all the ages of pasture regrowth combined in 1979 and 1980. The quadratic effect of N rate was not significant in either year.

The positive linear responses shown by the growth of tillers and the overall yield of the grass at N rates up to 400 kg/ha suggest that further work, using N rates above 400 kg/ha, is needed to ascertain the optimum N requirement of this grass.
Effects of bracken litter and frond canopy on emergence and survival of ryegrass and white clover seedlings
Authors: Lee H. C. , Cooke J. A.
Published: March 2009

Two field experiments, at Woolly Hills Farm, County Durham, UK, and a glasshouse experiment were carried out in 1977. Early in the growing season (May-July), a covering of bracken litter increased the number of ryegrass and clover seedlings which became established both in an area where bracken had been removed and where there were developing fronds. In a second experiment (August-October), bracken litter had no effect on seedling establishment in the open. Under the frond canopy, the absence of litter was beneficial to clover establishment. The frond canopy reduced the number of ryegrass seedlings by half compared with the numbers in the open. In the glasshouse, litter caused a small reduction in the numbers of ryegrass and clover seedlings becoming established.

The results suggest that litter may be either beneficial because of the prevention of desiccation in dry periods or detrimental, perhaps through allelopathic effects or shading. In terms of the successful establishment of a sown grass and clover sward, it would seem that litter removal by incorporation or burning is more justified in upland hill pastures because of the need to improve soil fertility than because of adverse effects of the litter itself.
A field study of the number of main shoot leaves in wheat in relation to vernalization and photoperiod
Authors: Kirby E. J. M.
Published: March 2009

The number of leaves formed on the main shoot of a wheat plant is an important developmental feature, and a method of predicting this is essential for computer simulation of development.

A model function was used to estimate vernalization from simulated sowing dates throughout a season. When expressed in terms of thermal time, it was estimated that a plant might be fully vernalized soon after seedling emergence or take up to about 1000 °Cd, depending on sowing date. When the simulated progress of vernalization was related to main shoot development (primordium initiation and leaf emergence) it was found that there were substantial differences between sowings in the rate of vernalization at comparable stages of apex development.

A number of field experiments done in Britain from 1980 to 1984 with prominent commercial varieties, sown at various times from September to March, were analysed in terms of the thermal time to full vernalization and the photoperiod at the time of full vernalization, with vernalization simulated by the model function. In both winter and spring varieties, both of these variables significantly affected the number of main shoot leaves. Multiple linear regression using these two variables accounted for between 70 and 90% of the variance in leaf number, depending on variety.
Analysis of post-flowering compensatory growth in winter oilseed rape (Brassica napus)
Authors: Tommey A. M. , Evans E. J.
Published: March 2009

Patterns of assimilate distribution in single plants of winter oilseed rape (Brassica napus L.) cv. Mikado, following a reduction in sink capacity at flowering were investigated in two field experiments during the 1985/86 and 1986/87 growing seasons at Cockle Park Experimental Station, Northumberland. Plants demonstrated considerable compensatory growth following the removal of flowers from the terminal raceme and primary branches.

Flower removal from lower branches did not significantly reduce total seed weight. Plants with a pod-bearing terminal raceme and one, two or three productive higher-order branches yielded a similar amount of seed. When seed production was confined to the terminal raceme and first four primary branches, seed yield per plant was greatly increased. Removal of flowers from the terminal raceme and uppermost branches of plants increased the number and productivity of lower-order branches but not enough to offset the overall loss in seed yield potential per plant. Indeed, when flowers were removed from higher-order racemes, the reduction in total seed weight per plant, was directly related to the degree of flower removal. The additional seed yield obtained from individual branches of modified plants in both experiments arose largely through an increase in fertile pod number and seed number per pod. Flower removal treatments did not greatly influence mean seed weight.

The results clearly demonstrated that the loss of flowers from lower-order branches could be tolerated and may even be beneficial. Conversely, the removal of flowers from higher-order branches resulted in significant yield reductions. The production of lower branches should be restricted, therefore, in order to increase the superiority of the terminal raceme and uppermost branches and to increase the overall production efficiency of the crop canopy.
Effects of plant population density on spring-sown field beans (Vicia faba) with different growth habits
Authors: Pilbeam C. J. , Duc G. , Hebblethwaite P. D.
Published: March 2009

Determinate varieties of Vicia faba are smaller and may require higher plant population densities than their conventional indeterminate counterparts to attain high yields. This hypothesis was examined at the University of Nottingham farm at Sutton Bonington, UK, and at INRA, Dijon, France in 1986 and 1987. The determinate varieties Ticol and TP667 and indeterminate M5.1 and Maris Bead were sown in the spring to give a range of densities of 10–100 plants/m2.

Yields generally increased as population density increased. The optimum density for determinate varieties was higher than for indeterminate varieties. Indeterminate varieties yielded more than determinate varieties at all plant densities, perhaps because of their larger canopy. Seed yields were affected by year and location. Greater yields were associated with heavier seeds and more seeds per pod.

Although several yield components, when expressed per unit area, were significantly correlated with seed yield, their coefficients of determination were never very large. This confirmed the plasticity of yield in field beans.
Carbohydrate digestibility and nitrogen metabolism in sheep fed untreated or sulphur dioxide-treated wheat straw and poultry litter
Authors: Miron J. , Solomon R. , Yosef E. , Ben-Ghedalia D.
Published: March 2009

Digestibility of neutral detergent fibre (NDF) and monosaccharide components of diets containing 60% untreated straw (UTS) or straw treated with sulphur dioxide (TS) and poultrylitter (1:1) plus 40% concentrate at 700 g/day intake was examined in sheep equipped with rumen and duodenal cannulas. An all-concentrate diet (CD) served as a reference ration. The SO2 treatment of straw increased the apparent digestibility of the NDF, glucose, xylose, arabinose and galactose components of the diet from 58·9, 86·7, 55·7, 82·5 and 91·8%, respectively, in the UTS diet to 73·8, 92·6, 77·8, 88·9 and 94·6%, respectively, in the TS diet. Whereas digestion of NDF and glucose in sheep on the TS diet was slightly lower than in those on the CD diet, digestion of xylose, arabinose and galactose was higher. Thus, the digestibility of total monosaccharides in th TS diet was 90·2 % and that of the CD diet only 61% units higher. The SO2 treatment also increased the total rumen volatile fatty acid (VFA) concentration and the proportion of butyric acid in the total VFA compared with the UTS diet.

Rumen ammonia concentration was 7 mg/100 ml lower and nonammonia nitrogen (NAN) flowto the duodenum was 1·3 g/day higher in sheep fed the TS diet compared with the CD diet. The quantity of duodenal N absorbed in the intestine was 10·7 g/day in the TS diet, close to the value of 11·6 g/day found with the CD diet.

The similarity between the TS and CD diets in total monosaccharides digestion and duodenal Nabsorption, confirms the findings of earlier studies that a TS diet is a highly productive ration.

Complementary interaction between the SO2-treated straw and poultry litter components of the TS diet is discussed.
Mathematical modelling of ammonia volatilization from slurry stores and its effect onCryptosporidiumoocyst viability
Authors: Ruxton G. D.
Published: March 2009

A simple mathematical model is shown to provide reasonably good predictions of time series data on ammonia loss from three experiments on slurry stores. The model produces predictions of changes in the distribution of ammonia with depth. Experimental evidence suggests that ammonia concentrations above a critical value appear to destroy the viability ofCryptosporidiumoocysts. Using this criterion, the model predicts that, even under the most favourable circumstances, oocysts are unlikely to remain viable in slurry stores except in the top few centimetres. The effect of stirring the slurry is considered.
Protein metabolism in lambs from lines divergently selected for weaning weight
Authors: Oddy V. H. , Speck P. A. , Warren H. M. , Wynn P. C.
Published: March 2009

The physiological consequences of selection for weaning weight were investigated using 14-month-old castrated male Merino lambs from lines selected for (W +) and against (W – ) weight at weaning for over 10 generations. The selection experiment commenced in 1953 and was conducted at Trangie, NSW, Australia. Lambs from these lines now differ by 42% in weight at weaning and maturity, and have a proportionately similar composition of protein, fat and ash in their bodies at similar stages of maturity. In the whole body, there were no apparent between-strain differences in protein synthesis, but W + lambs had lower (P < 0·05) rates of phenylalanine oxidation than W – lambs. In hind limb muscle, protein metabolism of W + lambs was more responsive to food intake than in W – lambs. In particular, the rate of change of protein degradation differed (P < 0·05) between the lines in response to food intake per unit liveweight with protein degradation decreasing with increased feed intake in W + lambs. W + lambs had lower (P < 0·05) rates of blood flow to, and used less (P < 0·05) oxygen per kg hind limb muscle than W— lambs. Endocrine differences between the lines included increased (P < 0·05) plasma insulin-like growth factor-I (IGF-1) concentration in W + compared to W— lambs and, from regression analysis, an indication that there was a higher (P < 0·01) response in hind limb protein gain to insulin in the W + lambs.

These results suggest that selection for weaning weight has altered the dynamics of protein metabolism in lambs, principally through alterations in protein breakdown in muscle. Moreover, they suggest that there are associated genetic differences in endocrine control of protein metabolism which involve insulin and possibly IGF-I.
Interactions between genotype and density on the yield components of Zea mays:II. Grain production
Authors: Voldeng H. D. , Blackman G. E.
Published: March 2009

Six hybrids, either pure dent or flint x dent crosses, together with two open-pollinated flint varieties of early maturity, were grown at Oxford, England, and the yield of grain determined over a range of 15 densities (5.30.8 plants/m2). The relationship of yield to density was studied by fitting mathematical functions to the observed yields. Only two functions, (1) the inverse quadratic on yield per unit area, and (2) the linear regression between density and the logarithm of grain yield per plant, were satisfactory fits. The linear regression was preferred because of its ease of calculation and interpretation. Between genotypes the largest differences in grain yield per unit area were found at densities either above or below those which are employed in normal practice.

The ranking of the genotypes for grain production depended upon the density. Whereas at the lowest density a very short, early-maturing flint genotype, GaspéFlint, yielded least, and a tall, full season dent hybrid, 0X324, yielded most, this position was reversed at the higher densities. Maximal levels of yields of the open-pollinated flint varieties were low, and it is apparent that the incorporation of this source of germplasm in hybrids is limited if commercially acceptable yields are to be attained. Maximal yields of 600 g/m2 were produced by three hybrids, but the optimal densities were markedly divergent. They ranged from 6.2 plants/m2 for 0X324 to 9.7 and 10.8 plants/m2 for INRA 270 and INRA 200. Possible reasons for such differences are discussed in terms of the interactions of density and genotype on the components of yield.
Effects of sulphur fertilizers and of copper on the yield and composition of spring wheat grown in an sandy soil prone to surface compaction
Authors: Bolton J.
Published: March 2009

A condition known as ‘scorch” with symptoms similar to copper deficiency often occurs in dry weather on cereals grown on a sandy soil (at Woburn) with an unstable structure. Plants with symptoms contained more sulphur than normal and sulphur/ copper interactions were suspected.

Sulphur fertilizers tested in two pot experiments with this soil did not induce copper deficienciesbut increased grain and straw yields of spring wheat especially at higher nitrogen rates. Yields were increased when the mature grain contained less than 0.12% S and the straw less than 0.5% Sin the dry matter. Sulphur concentrations were larger in plants grown in the greenhouse rather than in growth cabinets and in plants grown in oven-dried rather than air-dried soil.

Soil-applied copper sulphate slightly increased grain yields in pots but in one experiment there were no corresponding increases in copper contents of the crop. In a field experiment where ‘scorch’ symptoms occurred in 1972, copper oxychloride sprays increased copper concentrations but not yields of the grain.

These results suggest that copper deficiency is unlikely to be a primary cause of ‘scorch’ symptoms.
Relationships between the times of transplanting, curd initiation and maturity in cauliflower
Authors: Wurr D. C. E. , Fellows J. R. , Hiron R. W. P.
Published: March 2009

In order to determine the accuracy of controlling the time of maturity of a cauliflower crop by regulating the planting date, a series of transplantings of the variety White Fox was grown on a range of sites over 3 years and sampled throughout growth.

The time from transplanting to maturity and the time from curd initiation to maturity were both quadratically related to the time of transplanting but there were marked differences in the relationships between years. Differences between years in the time taken to reach maturity tended to increase with later transplanting; for example, cauliflower crops transplanted in May took between 77 and 94 days to mature, while those transplanted in July matured in as few as 67 or as many as 106 days. These differences resulted from a combined effect of the time taken to satisfy the vernalization requirement and the duration of curd growth, both of which are temperature-mediated and therefore subject to seasonal and annual variation. Differences in the vernalization requirements of different cauliflower crops are illustrated by the number of leaves formed before curd initiation, which varied from 22·5 to 37·3.

Variation in the time to maturity between crops transplanted at similar times of the year, in the same and different years, resulted in large deviations from planned production programmes and it is suggested that a complementary technique to aid crop marketing would be prediction of the time of crop maturity. However, the data collected in this study show that predictions based on the duration of crop growth from transplanting or curd initiation are unlikely to be sufficiently accurate and it is argued that predictions should be based on changes in curd dimensions with time.
Estimation of pituitary secretion rate during the reproductive cycle of sheep
Authors: Lindsay K. S. , Fleet I. R. , Walters D. E. , Heap R. B.
Published: March 2009

A technique has been developed for the measurement of pituitary hormone secretion rates in conscious sheep. The technique involves the continuous and simultaneous sampling of blood from the carotid artery and jugular vein and the measurement of cephalic blood flow by an indicator dilution technique. Veno-arterial differences in hormone concentrations multiplied by cephalic blood flow gave average secretion rates which were measured after single or repeated large doses of luteinizing hormone releasing hormone (LHRH) and thyrotrophin-releasing hormone (TRH) at various times in the reproductive cycle.
A study of root and shoot interactions between cereals and peas in mixtures
Authors: Tofinga M. P. , Paolini R. , Snaydon R. W.
Published: March 2009

Wheat, barley and two morphologically contrasting cultivars of peas (leafy and semi-leafless) were grown in pure stands, at standard agricultural densities, and in additive mixtures of cereals with peas. The stands were grown in boxes in the field, and partitions were used to separate the effects of root and shoot interactions. The cereals and peas were either planted at the same time, or one species was planted 10 days before the other. The origin of the N present in each species was determined by applying N fertilizer labelled with 15N.

Both cultivars of peas had greater shoot and root competitive abilities than wheat or barley, probably because of their larger seed size; leafy peas had greater shoot and root competitive abilities than semi-leafless peas. Sowing peas after cereals reduced their competitive ability.

The relative yield total (RYT) of cereal-pea mixtures, based on total biomass, averaged 1·6 when only the root systems interacted, and 1·4 when only the shoot systems interacted, but did not differ significantly from 10 when both root and shoot systems interacted. RYT values were greater when peas were grown with wheat, rather than with barley, and when peas were sown at the same time as the cereals.

Shoot competition from peas increased the N% of cereals, but substantially reduced their total N content, because biomass yield was reduced. Shoot competition from cereals had no effect on the N% of peas, and only slightly reduced their total N content. Shoot competition between cereals and peas had no significant effect upon the proportion of N derived from various sources by either cereals or peas.

Root competition from peas significantly reduced both the N% and total N content of cereals. Root competition from cereals had little effect on the N% of peas, but significantly reduced their total N content and increased the proportion of N derived from rhizobial fixation from 76 to 94%. Since cereals and peas largely used different sources of N, resource complementarity for N was probably an important component of intercropping advantage, when the roots of cereals and peas shared soil resources.
Amino acid composition of degradation-resistant peptides in extracellular rumen fluid of sheep
Authors: Wallace R. J. , Newbold C. J. , Watt N. D. , Buchan V. , Brown D. S.
Published: March 2009

Rumen fluid was removed from four sheep 6 h after feeding, and the fluid was centrifuged to remove the micro-organisms. Perchloric acid (PCA) was added to the supernatant fluid to precipitate soluble proteins, which were again removed by centrifugation. The PCA extract was neutralized with KOH and the precipitate was removed by centrifugation. The supernatant fluid was hydrolysed with 6 MHC1 at 110 °C for 24 h, then dried by rotary evaporation, and the amino acid composition of each extract was analysed by ion-exchange chromatography. The recovery of amino acids was 98%, except for methionine, cysteine and tryptophan, which were destroyed. The recovery of amino acids from added Trypticase was 92% of the peptide mixture as amino acids. The free amino acid composition of extracellular rumen fluid was low and variable in both amount and composition (0·36, S.D. 0·49, μmol/ml). The concentration of amino acids released by acid hydrolysis of the PCA extract, presumed to be derived from peptides, was larger and its composition was less variable (1 ·02, S.D. 0·30, μmol/ml). Aspartic acid and histidine were enriched in peptides in comparison with the amino acids present in the feed or in rumen particulate material. Glycine and proline contents were higher in peptides that in particulate material. In contrast, the contents of isoleucine, leucine, tyrosine and phenylalanine tended to be lower in peptides than in the other materials. It was concluded that extracellular degradation-resistant peptides had a composition that was different to microbial protein and to the feed. The peptides appeared to be enriched for amino acids which previous studies with pure peptides had shown tend to make peptides more resistant to degradation.
Frequency distribution of shoot weight of plants in populations ofTrifolium repenspersisting by clonal growth in grazed pastures
Authors: Hay M. J. M. , Thomas V. J. , Brock J. L.
Published: March 2009

Over two years (1984/85 and 1986/87), monthly sampling of shoots of white clover plants compared the populations of white clover in mixed swards at Palmerston North, New Zealand, under set stocking, rotational grazing and a combination of both systems, at a common stocking rate of 22·5 ewe equivalents/ha.

The frequency distributions of shoot (or stolon) dry weight per plant in each population over the study period was described by a log-normal model, which indicated that the populations consisted of many small individuals and few large individuals. Such inequality of shoot dry weight within populations is commonly termed size hierarchy; a statistic giving a measure of such size hierarchy is the Gini coefficient. The populations under different managements had similar Gini coefficients which differed little among seasons or between years. Lack of significant correlation between the Gini coefficient and mean shoot dry weight per plant of each population indicated that, in these white clover populations, size hierarchy was independent of mean plant size.

These results were considered in relation to the clonal growth of white clover in grazed swards and it is suggested that the variable nature of death of older basal stolons makes an important contribution to the variability in size of individual plants and hence to size hierarchy. As size hierarchy, as assessed by Gini coefficients, was relatively stable in these populations over 3½ years, it appears that clonal growth of white clover incorporates sufficient variability within the growth and death processes at the individual plant level to maintain the size hierarchy, irrespective of variations in mean plant size of populations.
Sensitivity analyses of the ARCWHEAT1 crop model: the effect of changes in radiation and temperature
Authors: Kocabas Z. , Mitchell R. A. C. , Craigon J. , Perry J. N.
Published: March 2009

The sensitivity of predicted final grain yield to changes in the mean and variance of daily temperature and daily log(radiation) was studied for the arcwheat1 crop model of winter wheat. These two climatic variables were each simulated by each of two stochastic models, the parameters of which were estimated from 12 years' data from Rothamsted Experimental Station.

When arcwheat1 was run with systematic changes in daily temperature from – 2 °C to +2 °C in steps of 0·1 °C, there were abrupt changes in predicted final grain yield which coincided with predicted increases in leaf number. These effects were smoothed out when the stochastic climate models incorporating simulated daily variation were used as inputs, in multiple runs of arcwheat1.

In such runs, the response of predicted yield to changes in the means of temperature and log(radiation) was studied both for individual developmental stages and over the entire growing season. Yield was insensitive to changes in temperature and radiation during the stage between sowing and emergence, and to changes in radiation before terminal spikelet formation.
Influence of ionophores and energy inhibitors on peptide metabolism by rumen bacteria
Authors: Wallace R. J. , Newbold C. J. , McKain N.
Published: March 2009

Ionophores and inhibitors of bacterial energy metabolism were added to mixed rumen bacteria prepared from sheep receiving grass hay plus concentrate diets, and their influence on the rate of metabolism of alanine (Ala) peptides was determined. Dicyclohexylcarbodiimide (DCCD) had no influence on the rate of breakdown of Ala2, Ala3, Ala4or Ala5, indicating that the metabolism of these peptides did not require ATP. The protonophores tetrachlorosalicylanilide (TCS) and carbonyl cyanidem-chlorophenyl-hydrazone (CCCP) inhibited peptide breakdown to a minor extent (< 15%), whereas the ionophores monensin and tetronasin had greater, but still small (12–31%), inhibitory effects. Toluene stimulated peptide breakdown, consistent with a permeability barrier having been removed. Thus, at least some peptide metabolism depends on transport into bacteria; transport appears not to be ATP-linked, and may well be coupled to the uptake of mineral cations rather than protons. Rumen fluid from sheep receiving a similar diet with added monensin (33 mg/kg) or tetronasin (10 mg/kg) hydrolysed Ala3and Ala4at rates that did not differ significantly from controls. Nevertheless, the peak concentration of free peptides in rumen fluid after feeding was more than doubled in ionophore-fed sheep, and peptides persisted for longer than in control animals.
Crop patterns recorded on aerial photographs of England and Wales: their type, extent and agricultural implications
Authors: Evens R.
Published: March 2009

Crop patterns of natural origin and man-created crop marks are frequently recorded on aerialphotographs taken over England and Wales. They usually indicate subsil variation over short distances, but differences in crop growth may also be evident in relation to topsoil variability. Different kinds of crop patterns and the soils on which crop patterns and marks develop are briefly described. Soil associations in which crop patterns and marks are frequently and extensively recorded cover 25% (37664 km2) of England and Wales; in dry years, patterns and marks are extensively recorded over a further 6·5% (9884 km2). Crop patterns and marks indicate that over much of England and Wales crop growth may be impeded by properties intrinsic to the soil, which are not easily ameliorated by farmers. When siting crop experiments, care should be taken to avoid these areas of complex soil patterns.
Association of differences in seed vigour in long bean (Vigna sesquipedalis) with testa colour and imbibition damage
Authors: Abdullah W. D. , Powell A. A. , Matthews S.
Published: March 2009

Field emergence of 11 seed lots from six cultivars of long bean, all having laboratory germination of > 80%, ranged from 0 to 83%, indicating differences in seed vigour. Vigour differences occurred within and between cultivars, seed lots from cultivars with white or partly white testas having particularly poor emergence (0–21%) compared with those with brown or black testas (41–83% field emergence). The significant ranked correlations between field emergence and (i) solute leakage, measured by the electrical conductivity of seed soak water (r = –0·864), (ii) the percentage of cotyledons made up of completely living tissue, revealed by vital staining (r = 0·895), and (iii) the proportion of hard seeds (r = 0·916) indicated that lots with low vigour and potentially poor field emergence could be identified before sowing. Seed lots having low vigour imbibed water rapidly; the improved vital staining when seeds imbibed slowly indicated that damage occurred during imbibition and was a cause of low seed vigour. Rapid water uptake by low-vigour seed lots was partly explained by the incidence of seeds with cracked testas, but other factors could not be eliminated. The significance of differences in water uptake between cultivars differing in testa colour is discussed in relation to breeding for improved emergence.