bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of separation and acidification of cattle slurry on ammonia volatilization and on the efficiency of slurry nitrogen for herbage production
Authors: Frost J. P. , Stevens R. J. , Laughlin R. J.
Published: March 2009

During the growing season of 1988 at the Agricultural Research Institute, Hillsborough, cattle slurry was kept whole or was separated through screens with mesh sizes of 5 mm, 3 mm, 0·25 mm and 0·015 mm. The resulting slurry liquids were either left unacidified or were acidified to pH 5.5 with 5M-H2SO4 prior to application at 75 kg NH+4-N/ha to perennial ryegrass in the field. Volatilization of ammonia was measured using ventilated enclosures. Plots treated with a range of rates of inorganic fertilizer N were used to construct response curves to assess the efficiency of N in slurry for herbage production compared with equinitrogenous inorganic fertilizer.

On average over the season, acidification of cattle slurry decreased ammonia volatilization to < 15% of that from unacidified whole slurry. Compared with inorganic fertilizer N, the overall efficiency of NH+4-N was 96% in acidified slurries and 36% in unacidified whole slurry. Ammonia volatilization from separated slurries decreased with decreasing mesh size to 39% of that from whole slurry for a 0·015 mm mesh. The overall efficiency of NH4+-N in slurry separated through a 0·015 mm mesh was 76%. A highly significant linear relationship was found between NH3-N volatilized from all slurry treatments and N offtake in herbage at all three harvests.
Cell membrane stability, an indicator of drought tolerance, as affected by applied nitrogen in soyabean
Authors: Premachandra G. S. , Saneoka H. , Ogata S.
Published: March 2009

Four soyabean cultivars were grown with two N application rates (50 and 300 kg N/ha) in the field at Hiroshima University, Japan, from June to August 1988. Cell membrane stability (CMS) by the polyethylene glycol (PEG) test, leaf water relations and nutrient concentrations in cell sap and leaf tissues were measured when the plants were 50 days old, in the uppermost fully expanded leaves.

Cell membrane stability was higher at the higher N rate, the increase over the lower rate being greater in the cultivars Lee+ and Lee–than in Tamahomare and T201. Leaf water potential was not affected by the higher rate of N application. Osmotic adjustment, which was independent of water stress, was observed with the higher rate of N and it was higher in Lee + and Lee–than in Tamahomare and T201. It is suggested that osmotic potential in leaf tissues may influence CMS measured by the PEG test. Solute concentrations in cell sap and leaf tissues were higher at the higher N rate. Sugar and K were the major contributors to osmotic potential.
Culinary quality of tubers derived from Solanum phureja and S. tuberosum × S. phureja hybrids
Authors: De Maine M. J. , Carroll C. P. , Torrance C. J. W.
Published: March 2009

Clones from the potato species Solanum phureja and 2x and 4x hybrids between S. phureja and S. tuberosum were tested for the culinary quality of their tubers following steaming, frying and baking. The quality of S. phureja tubers was high but material from the F 1 hybrids showed more disintegration or blackening after cooking than either parental species. Tetraploids produced by backcrossing 4x Fl hybrids toS. tuberosum cultivars showed less of these defects.

Fourteen S. phureja and 2x F1 hybrid clones selected for their unusual tuber skin pigmentation or shape were found to have a variety of baked flesh colours from orange-yellow to cream with red marbling. Their cooked flesh texture was generally floury and often crumbly. It is suggested that S. phureja material could be exploited as a novel food source for specialized use in North European countries.
Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep
Authors: Sinclair L. A. , Garnsworth P. C. , Newbold J. R. , Buttery P. J.
Published: March 2009

The effects of two diets formulated to be either synchronous or asynchronous with respect to the hourly supply of energy and nitrogen on rumen fermentation and microbial protein synthesis were studied in sheep.

In Expt 1, the insitudegradation characteristics of nitrogen (N), organic matter (OM) and carbohydrate (CHO) fractions were determined in winter wheat straw, winter barley, malt distillers dark grains rapeseed meal and fishmeal. The feeds exhibited a large range in degradability characteristics of the nitrogen and energy-yielding fractions.

A computer program was developed based upon the raw material degradation characteristics obtained from the above studies. The program was used to formulate two diets with similar metabolizable energy (9·5 MJ/kg DM) and rumen degradable protein contents (96 g/kg DM) but to be either synchronous (diet A) or asynchronous (diet B) with respect to the hourly rate of release of N and energy. The program was used to predict the hourly release of N, OM and CHO and the molar production of volatile fatty acids (VFA).

In Expt 2, the two diets were fed to four cannulated sheep at the rate of 1 kg/day in four equal portions, in two periods, using a change-over design. Rumen ammonia concentrations followed the predicted rate of N degradation. A maximum concentration of 10·5 and 7 mM for diets A and B respectively was achieved within the first hour of feeding which then fell to 7 and 3 mM respectively. Rumen VFA proportions were more stable for the synchronous diet (A) than the asynchronous diet (B) and were more stable than predicted for both diets. True ruminal degradation of OM and CHO was similar for both diets and close to that predicted, although fibre degradability in diet A was 30% lower than predicted due to a reduction in both cellulose and hemicellulose digested. Microbial protein production was estimated simultaneously with L-[4,5–3H]leucine and a technique based on cytosine. Estimates varied with marker but mean values indicated a 27% greater production of microbial N (g N/kg DM I) with the synchronous diet (A) and an average improvement in microbial protein efficiency (g N/kg OM truly degraded or CHO apparently degraded) of 13%, although neither difference was significant. There was evidence of a greater recycling of N in the animals and a significantly lower content of rumen degradable protein when the sheep were fed the asynchronous diet (B).

The results are consistent with the view that synchronizing the rate of supply of N and energyyielding substrates to the rumen micro-organisms based upon ingredientin situdegradation data can improve microbial protein flow at the duodenum and the efficiency of microbial protein synthesis.
Inter-plot interference and nearest-neighbour analysis of field experiments
Authors: Ainsley A. E. , Dyke G. V. , Jenkyn J. F.
Published: March 2009

Results obtained from the plots of a field experiment may be subject to’ representational errors'; that is, they may not exactly reproduce the results that would be expected if the same treatments were applied to whole fields. In particular, the treatment applied to one particular plot often has the potential to affect the adjacent plots; such an effect may be positive or negative according to circumstances, and its magnitude cannot easily be estimated. This paper shows, on theoretical grounds and by simulations, that nearest-neighbour (NN) analysis cannot be relied upon to mitigate the effects of such inter-plot interference, even when the residual variance of the NN analysis is substantially, and by normal criteria significantly, smaller than that of conventional (randomized block) analysis. In certain circumstances, NN analysis of data affected by interference produces greater average bias in estimated treatment differences than conventional analysis.
Assessment of groundnut cultivars for end-of-season drought tolerance in a Sahelian environment
Authors: Ndunguru B. J. , Ntare B. R. , Williams J. H. , Greenberg D. C.
Published: March 2009

A 2–year study (1990 and 1991) was conducted at the ICRISAT (International Crops Research Institute for the Semi-Arid Tropics) Sahelian Centre, near Niamey, Niger, to select groundnut cultivars tolerant to drought and to examine selection techniques. Thirty-six cultivars known to vary in yield potential were grown under rainfed and irrigated conditions. Crop growth rate (C) and partitioning co-efficient (p) were estimated from phenological and final harvest data. The correlation between years was greater for partitioning than for pod yield (implying a higher heritability for p than for yield). Tolerance as determined by a drought susceptibility index for pod yield (SY), crop growth rate (Sc) and partitioning (Sp) to reproductive sinks showed thirteen cultivars as drought tolerant for either C or p or for both. The Sahelian cultivars 796, 55–437 and TS 32–1 were the most consistent for drought tolerance. Partitioning was the most important yield component affecting yield variation among cultivars.
Effects of plant density and inorganic nitrogen fertilizer on field beans (Vicia faba)
Authors: Aguilera-Diaz C. , Recalde-Manrique L.
Published: March 2009

A factorial experiment on Vicia faba L. cv. Alameda with three plant densities at three levels of nitrogen fertilization was done for three years (1984–87) at Granada. Yield varied markedly from 403 to 579 g/m2 between seasons. The mean increase in plant population density from 10 to 16 plants/m2 raised seed yield, but a further increase to 21 plants/m2 did not increase yield significantly. There was, however, considerable variation in the response to increasing density (Dl to D3) within each N level (N0, N1 and N2). Application of 30 kg N/ha at the start of flowering increased mean seed yield only at the lowest plant density and in 1986, but 60 kg N/ha increased yield by 135% on average over the 3 years. The highest N application rate resulted in consistently higher overall yields at each plant density. Leaf area index (LAI) showed a significant increase at 20 seeds/m2 compared with that at 10 seeds/m2 but there was no further increase at 30 seeds/m2. Harvest index (HI) was mainly affected by the annual weather conditions, and ranged from 47–4 in 1986 to 62–6 in 1987. HI was related to the mean temperature at flowering (April).
Dietary preferences of sambar (Cervus unicolor) and red deer (Cervus elaphus) offered browse, forage legume and grass species
Authors: Semiadil G. , Barry T. N. , Muir P. D. , Hodgson J.
Published: March 2009

Grazing sambar and red deer in New Zealand were offered a free choice of seven different plant species (forage legumes, browse and grasses) in 1992 and 1993 and dietary preference rankings were determined. Nutritive value of plants on offer and diet selected, plant height, plant species purity and stem diameter selected (browse only) were also determined. Total nitrogen (N) and organic matter digestibility (OMD) were highest for red clover, lowest for grasses and intermediate for browse species (willow, poplar and lupin). Top dietary preference ranking was willow for sambar and red clover for red deer in both years, with Yorkshire fog and prairie grass being lowly preference ranked with both deer species. Sambar selected willow stems up to 38 mm in diameter and poplar stems up to 54 mm in diameter. When the plants were grouped into browse, grass and forage legume categories, both deer species showed a similar preference ranking for grasses. Relative to grasses, sambar showed a strong preference for browse and a low preference for forage legumes, whilst red deer showed a strong preference for forage legumes of high nutritive value and a very low preference for browse. It was calculated that sambar selected a total diet higher in condensed tannins and lignin but lower in nitrogen than that selected by red deer, with similar values for total fibre and OMD. Differences in dietary preference between the two deer species may be linked with the greater ability of sambar deer to neutralize some plant secondary compounds and their more efficient rumination pattern compared with red deer. Both sambar and red deer can be classified as intermediate feeders, having a similar preference for grasses, but differing preferences for forage legumes and browse.
Effects of forage to concentrate ratio in the diet and protein intake on the performance and carcass composition of beef heifers
Authors: Robson A. E.
Published: March 2009

Isoenergetic diets containing grass silage and concentrates in the ratios 75:25; 50:50 and 30:70 on a dry matter (DM) basis were offered to 42 beef heifers, which were initially 361 kg liveweight, for 115 days in 1987 at Hillsborough, Northern Ireland. Half of the animals given each forage concentrate ratio were given one of two crude protein (CP) intakes in a 3 × 2 factorial design. The silage contained 152 g CP/kg DM, 94 g ammonia-N/kg total N and 734 g digestible organic matter/kg DM. Concentrates were based on barley and soyabean meal and were formulated to equalize CP intakes for the three forage: concentrate ratios. For diets containing 75, 50 and 30% silage, metabolizable energy intakes were 94, 92 and 87 MJ/day; liveweight gains 0·99, 1·07 and 1·12 (S.E. 0·051) kg/day; carcass gains 0·61, 0·64 and 0·67 (S.E. 0·033) kg/day; carcass lean concentrations (estimated from dissection of fore-rib joints) 636, 642 and 648 (S.E. 4·7) g/kg and carcass fat concentrations 204, 199 and 194 (S.E. 5·3) g/kg. Increasing protein intake did not affect performance, but increased carcass fat concentration at all three forage concentrate ratios. It was concluded that increasing the proportion of concentrates in grass silage-based diets increased carcass weight gain per MJ of metabolizable energy consumed and tended to reduce carcass fatness. Contrary to previous findings with young growing cattle, increasing protein intake did not alleviate the problem of greater fat deposition in finishing cattle given high-silage diets, but rather significantly increased carcass fat concentration.
Ketogenesis in the liver of ruminants – adaptations to a challenge
Authors: Zammit V. A.
Published: March 2009

The descriptive aspects of hepatic fatty acid metabolism, and of ketogenesis in particular, have been extensively described for ruminants. There is, however, a distinct lack of information on the more mechanistic aspects of the subject. The biochemical profile of the livers of ruminant species shows both similarities to, and striking differences from, that of simple-stomached animals. Consequently, it may not always be valid to extrapolate from the situation in, say, rat liver to that in ruminant liver in order to interpret experimental observations in ruminants. Of perhaps greater interest is the recognition that the adaptations in the ruminant system are important not only in enabling us to rationalize the physiological changes observed in ruminants, but are in themselves of interest in the analysis of metabolic regulatory strategies. Consequently, this review deals with the peculiarities of the regulation of hepatic ketogenesis in ruminants, and the biochemical mechanisms that may explain their existence.
Response of an old pasture to applied nitrogen under steady-state continuous grazing
Authors: Tallowin J. R. B. , Kirkham F. W. , Brookman S. K. E. , Patefield M.
Published: March 2009

The response of an old, unimproved mixed-species pasture to fertilizer nitrogen was examined under 4-weekly cutting or continuous grazing with young beef cattle. Five N fertilizer rates were applied: zero, 100, 200, 400 or 800 kg/ha per year. The investigation was carried out in Devon, on a heavy clay soil in a region of high winter rainfall in 1984, 1985 and 1986.

Annual total herbage dry-matter (DM) production, live weight gain (LWG) and utilized metabolizable energy (UME) output all increased with successive increments of fertilizer N up to 400 kg N/ha per year. Under 4-weekly cutting, the response per kg applied N fell below 10 kg DM at an application rate of 268 kg N/ha per year, giving a yield of 10·6 t/ha per year. Under grazing, the overall response during the grazing season per kg applied N fell below 300 kg live weight carried per ha at a fertilizer rate of 248 kg/ha per year, giving a UME output of 78 GJ/ha over the grazing season. High available soil N contributed to the high productivity from these swards. Animal output at moderate (200 kg N/ha per year) N application rates did not appear to be constrained by the initial botanical composition of this unimproved sward. Repeated high N applications in the 400 kg N/ha per year treatment reduced output in 1986 under grazing and cutting, compared with treatments which had received the lower N applications.

The DM yield from the 4-weekly cutting study gave a satisfactory prediction of UME output from this pasture. Climatic conditions, particularly high rainfall, appeared to be an important constraint on animal performance at pasture.

The high UME output achieved from this pasture at 200 kg applied N/ha was well above the average UME for commercial farms.
Effects of field beans, fallow, lupins, oats, oilseed rape, peas, ryegrass, sunflowers and wheat on nitrogen residues in the soil and on the growth of a subsequent wheat crop
Authors: McEwen J. , Darby R. J. , Hewitt M. V. , Yeoman D. P.
Published: March 2009

The effects on a winter wheat test crop of a preliminary year of winter or spring field beans (Vicia faba), winter oats, winter oilseed rape, winter or spring peas (Pisum sativum), winter wheat, spring lupins (Lupinus albus), spring sunflowers (Helianthus annuus) or a cultivated fallow were compared in three 2-year experiments on clay-with-flints soil at Rothamsted from 1986 to 1989. In one experiment, autumn-sown ryegrass (Lolium perenne) and an uncultivated fallow, given weedkiller, were also included in the first year. Plots of test-crop wheat were divided to compare no N fertilizer with an optimal amount estimated from a predictive model.

Amounts of take-all (Gaeumannomyces graminis) in the test crop of wheat following wheat were very slight in the first experiment, but large in the second and third. All the break crops reduced takeall to none or very slight amounts.

Amounts of NO3-N in the soil in autumn after the first-year crops ranged from 7 to 95 kg N/ha. On average, they were least after oats, and most after cultivated fallow. In autumn 1988they were least after autumn-sown ryegrass. In early spring, amounts of NO3-N were generally less, ranging from 7 to 55 kg N/ha, depending on preceding crops, sowing date of the wheat and the weather. Amounts of NH4-N in soil were little affected by preceding crops or weather and were generally smaller in spring.

The estimated average N fertilizer requirement of test-crop wheat following winter wheat was
230kg N/ha. This was increased by 10 kg N/ha following winter oats, decreased by 40 kg N/ha after spring peas and by 30 kg N/ha after winter rape, winter peas, spring beans and cultivated fallow. Other preliminary crops not represented every year had effects within this range.

Grain yields of test-crop wheat given optimal N averaged 7·2 t/ha after winter wheat, c.1·5 t/ha less than the average after most of the break crops. The yield after oats was limited by self-sown ‘volunteers’ and that after ryegrass by limited soil N after ploughing.

Of the break crops tested, winter and spring beans, winter oats, winter rape and spring peas all gave satisfactory yields. A farmer should choose between these on the basis of local farm circumstances and current economics of the break crops. Differences between effects on take-all and savings on fertilizer N were too small to influence this decision.
Growth and yield responses of rice to carbon dioxide concentration
Authors: Baker J. T. , Allen L. H. , Boote K. J.
Published: March 2009

Rice plants (Oryza salivaL., cv. IR30) were grown in paddy culture in outdoor, naturally sunlit, controlled-environment, plant growth chambers at Gainesville, Florida, USA, in 1987. The rice plants were exposed throughout the season to subambient (160 and 250), ambient (330) or superambient (500, 660, 900 μmol CO2/mol air) CO2concentrations. Total shoot biomass, root biomass, tillering, and final grain yield increased with increasing CO2concentration, thegreatest increase occurring between the 160 and 500 μmol CO2/mol air treatments. Early in the growing season, root:shoot biomass ratio increased with increasing CO2concentration; although the ratio decreased during the growing season, net assimilation rate increased with increasingCO2concentration and decreased during the growing season. Differences in biomass and lamina area among CO2treatments were largely due to corresponding differences in tillering response. The number of panicles/plant was almost entirely responsible for differences in final grain yield among CO2treatments. Doubling the CO2 concentration from 330 to 660 μmol CO2/mol air resulted in a 32 % increase in grain yield. These results suggest that important changes in the growth and yield of rice may be expected in the future as the CO2concentration of the earth's atmosphere continues to rise.
Effect of untreated or chemically upgraded barley straw with highly digestible grass silage on intake and performance of lactating cows
Authors: Phipps R. H. , Weller R. F. , Elliott R. J. , Givens D. I. , Moss A. R.
Published: March 2009

Between weeks 3 and 18 of lactation, 141 British Friesians all received concentrate (metabolizable energy (ME) 12·9 MJ/kg dry matter (DM), 202 g crude protein (CP)/kg DM) at 8·0 kg fresh weight/day. In addition, cows received ad libitum either grass silage (ME 11·7 MJ/kg toluene DM; 219 gCP/kg DM) or a mixture containing grass silage and 15, 25 or 40% (DM basis) of winter barley straw (cv. Igri) either untreated (UTS) or treated (TS) with 4% NaOH. Forage treatments were imposed at either week 3 or week 9 of lactation.

The mean forage DM intake of cows receiving grass silage only was 8·60 kg/day. When 15, 25 and 40% UTS was introduced into the rations at week 3 or 9 of lactation, forage DM intakes were 884, 8·43, 7·62 and 8·63, 8·83, 819 kg/day, respectively; the corresponding values for TS were 8·88, 855, 8·99 and 8·97, 8·98, 9·35 kg7sol;day. The milk yield of cows receiving grass silage only was 22·1 kg/day. When 15, 25 and 40% UTS was introduced into the rations at week 3 or 9 of lactation, milk yields were 21·1 kg/3, 20·1 kg/1, 20·1 kg/5 and 20·1 kg/1, 21·4, 20·5 kg/day, respectively; the corresponding values for TS were 21·8, 22·1, 21·3 and 22·5, 21·4, 22·6 kg/day. When averaged across the three inclusion rates, TS significantly increased forage intake (P < 0·05) and milk yield (P < 0·01) compared with UTS. Intermediate values were recorded for the diet with grass silage alone. The inclusion of TS in the ration did not affect milk yield compared with grass silage alone. No major changes in milk composition were recorded by the inclusion of either TS or UTS. However, the yields of milk fat, protein and lactose for the TS treatments were higher than for UTS and were significant for protein (P < 0·01) and lactose (P < 0·001). Cows with UTS in their ration tended to have lower live weight gains than either the control group or treatments with TS.

When compared with grass silage only, the inclusion of TS or UTS decreased digestibility coefficients and ME contents, determined in vivo using wether sheep fed at maintenance. However, the treatment of straw with NaOH (4%) increased its digestibility coefficients of dry matter from 0·-393 to 0·668, of organic matter from 0·445 to 0·686, of acid detergent fibre from 0·442 to 0·713, gross energy from 0·438 to 0·640 and ME content from 7·0 to 9·4 MJ/kg DM.
Uptake, cycling and fate of nitrogen in grass-clover swards continuously grazed by sheep
Authors: Parsons A. J. , Orr R. J. , Penning P. D. , Lockyer D. R. , Ryden J. C.
Published: March 2009

Components of the N cycle were studied at Hurley, UK, in 1985–87. In grass-clover (Lolium perenneandTrifolium repens) swards, grazed at three intensities, low total inputs of N were associated with low outputs and losses of N. Nevertheless, the flows (intake and excretion) of N through animals were substantial and gave rise, at the higher intensities of grazing, to an acceptably high agricultural output per hectare. This was considered evidence of a fast and efficient recycling of N between plants, animals and soil. The release of N to the environment (as nitrogenous gases and nitrate) was substantially less from the grass–clover swards than from a grass sward fertilized with 420 kg N/ha, and this was at the expense of only 20% loss in production. The mechanisms which might account for the high efficiency of utilization and recycling of N in grass–clover swards are discussed in the context of the balance of the supply of C and N to plant and soil biomasses under grazing. The results confirm that optimizing agricultural output in grass–clover swards has little adverse effect on the environment, but the importance to this end of sustaining a large proportion of N-deficient grass in grass-clover swards is emphasized.
Use of successional sowing in evaluating cowpea (Vigna unguiculata) adaptation to drought in the Sudan savannah zone. 1. Seed yield response
Authors: Muleba N. , Mwanke M. , Drabo I.
Published: March 2009

Two sets of experiments were conducted on oxic Plinthustalf and udic Ustochrept soils in 1983–85 at Ouagadougou, Burkina Faso. One set tested six daylength-insensitive (DI) cultivars and the other set compared four or five daylength-sensitive (DS) cultivars with one or two DI cultivars as controls, sown on three or four dates. Sowing date, cultivar and their interaction significantly affected seed yield in 1983 and 1985. In 1984, yield was not affected by sowing date in the DI cultivars nor by the sowing date x cultivar interaction in the DS cultivars. Optimum sowing dates were mid- and late July. Sowing earlier gave no yield advantage, whereas sowing later reduced yield severely.

The medium-maturing DI cultivar TN88–63 and the DS cultivar Koakin Local, which has a critical photoperiod in late August, exhibited average to below average yield stability but had a high mean yield and were considered well adapted in all conditions. The other cultivars were either moderately or poorly adapted to the Sudan savannah zone. The sowing date experiments were effective in identifying adapted cowpea cultivars, even from a single year's data, and can be used for screening cowpea for adaptation in the Sudan savannah zone.
Effects of short-term feeding of clenbuterol on nitrogen retention, performance and meat quality in finishing pigs
Authors: De Schrijver R. , Fremaut D. , Broeck M. Van Den
Published: March 2009

An experiment using 30 Belgian landrace finishing pigs was carried out, in 1989, at the University of Leuven, Belgium, to examine the effect of clenbuterol in the diet (1 mg/kg) on the repartitioning of nutrients and body composition. Clenbuterol was administered for 20 days preceding the week before slaughter. Fifteen animals were fed a diet containing the β-agonist, and 15 other animals served as negative controls. Weight gain, feed conversion and N utilization improved during β-agonist treatment. Removal of clenbuterol from the diet rapidly increased blood urea concentrations, indicating immediate, less efficient, N utilization. In the week before slaughter, the animals did not lose the extra weight gained in the period of clenbuterol feeding. Backfat thickness at slaughter was reduced by 15% in the animals fed clenbuterol. Dressing percentage and post mortem pH decline, colour and water-holding capacity in ham and the longissimus dorsi were not affected by dietary treatment. Clenbuterol was not detected in renal fat and the longissimus dorsi at slaughter.
Morphology of perennial ryegrass (Lolium perenne) plants in pastures under intensive sheep grazing
Authors: Brock J. L. , Fletcher R. H.
Published: March 2009

The morphology of independent plants of perennial ryegrass (Lolium perenneL.) in mixed swards under intensive sheep grazing was studied at Palmerston North, New Zealand in 1988/89. Intact plants of two cultivars, ‘Grasslands Nui’ and ‘Grasslands Ariki’, were sampled from pastures under rotational grazing, set stocking, and a combination of both systems, every 2 months for 16 months, by taking turves (250 × 250 mm) and washing out the plants. Characters measured for each plant were: number of flower heads, leaves and tillers; basal stem and internode stolon length; flower head, leaf blade, leaf sheath and stolon dry weight (DW). Additional pasture data on tiller density and dispersion and herbage DW to ground level were also collected.

Perennial rye grass exhibited a strong clonal growth pattern similar to that of white clover (Trifolium repensL.) but with a better balance between growth at the apex and death of old basal stem. Release of branch stolons to form new plants was regular, which maintained population stability. Formation of internode (I) stolon appeared to be a response of heavily shaded tillers for survival by elevation of the growing point to a more favourable position. The total DW of ryegrass stolon in pastures was greater than that of the companion white clover.

There was little seasonal variation in number of tillers or basal (B) stem length per plant. During the reproductive period (late spring/early summer) plants were heavier and had more leaves and internode stolon than at other times of the year. Grazing management had little effect on plant structure, but plants under rotational grazing had 75% greater DW, less basal stem and reduced probability of internode stolon formation than plants under set stocking. Nui plants had heavier but fewer tillers than Ariki did, resulting in little difference in plant DW. Ariki had fewer single-tiller plants and a higher proportion of multiple-tiller (> 7) plants than Nui had. The structure of the populations was not affected by season, management or cultivar and remained stable throughout the year, with a log-normal distribution of plant size. Because of the uniformity of plant structure, plant density in pastures paralleled tiller density, averaging 1900, 3360 and 2330 plants/m2for rotationally grazed, set stocked and combined grazing treatments respectively.

In view of the strong influence that grazing management can have on ryegrass performance and persistence in pastures, the lack of response at the level of plant and population structure to grazing management suggests that some other level of organization within the ecology of the pasture is of greater importance.
Evaluation of multipurpose tree germplasm: the use of gas production and rumen degradation characteristics
Authors: Siaw D. E. K. A. , Osuji P. O. , Nsahlai I. V.
Published: March 2009

The rumen degradation and gas production characteristics (methane, carbon dioxide) of leaves of 20 accessions of multipurpose trees (MPTs) from six genera: Acacia, Cajanus, Chamaecytisus (L. fil.) Link, Erythrina, Leucaena and Sesbania and some poisonous plants were investigated in vitro and in sacco in rumen fistulated cows fed on a diet of grass hay ad libitum supplemented with cotton seed cake. The degradation constants (i.e. the soluble fraction (a), the slowly degradable fraction (b) and the rate of degradation (c) and the potential degradability (a + b) (PD)) were calculated. The gas production constants were estimated following the equation: Volume = bg(1—e-cgt) where bg is gas production and cg is the rate of gas production. Between and within genus comparisons of degradability and gas production constants were done.

The soluble fraction (a) was significantly higher for Sesbania (59) (P < 0·05) than the other genera, which had values between 45·18 and 40·38 units. There were no significant differences in the slowly degradable fraction (b) between genera. Sesbania was degraded significantly faster (P < 0·05) than either Acacia, Leucaena or Cajanus. Similarly, the potential degradability was significantly higher (P < 0·05) for Sesbania (92·7) than for the other genera. Acacia was the least degradable genus.

Degradation characteristics were similar between species within the genera Acacia, Erythrina and Leucaena. However, within the Leucaena genus, L. revoluta had the highest soluble fraction (50·02) and the cross L. leucocephala × L. diversifolia had the lowest (29·24). L. leucocephala had the highest slowly degradable fraction (57·32) and L. revoluta had the lowest (42·37). L. leucocephala × L. pallida had the highest rate of degradability (0·0626) and L. pallida had the lowest (0·0221). L. leucocephala had the highest potential degradability (92·23) and the cross L. pallida × L. diversifolia the lowest (84–81).

Between the genera, more gas was produced from Sesbania than from any other genus. The effect of genus was significant (P <0·0003). On the other hand, the rate of gas production (cg) was higher with the genus Chamaecytisus than with any other genera (P < 0·0001). Although the two methods used agree in the position of a forage of a high degradability like Sesbania, they fail to agree on the relative positions of the forages of lower degradabilities. For some genera, drying of the tree foliage reduced the volume of gas produced, but increased the rate of gas production.
Soil inorganic-N and nitrate leaching on organic farms
Authors: Watson C. A. , Fowlerf S. M. , Wilman D.
Published: March 2009

On two organic farms, nitrate-N and ammonium-N in the surface layers of the soil of representative fields were recorded for 2 years. Nitrate-N was also determined in different soil layers down to 120 cm at the beginning, middle and end of two winters and at intervals after ploughing three fields, to seek evidence of leaching.

Nitrate-N and ammonium-N were both consistently low in the surface layers of fields in ley. Nitrate-N accumulated in arable soils on some occasions when there was little or no crop uptake of N, after ploughing, and after very heavy applications of manure.

There was some evidence of nitrate leaching in all five fields which were deep-sampled. In four cases, the loss by leaching appeared to be < 25 kg N/ha per winter. In the other case, in which a 4-year ley was ploughed on 5 October, the loss by leaching appeared to be c. 70 kg N/ha. Ploughing in winter, rather than early autumn, might have reduced the nitrate leached, but the drilling of the next crop might have been delayed.

The nitrate concentration of water draining from recently ploughed sandy soil in Shropshire was high, but it would have been diluted by water draining from unploughed fields.
Phenotypic stability of oats measured with different stability analyses
Authors: Peltonen-Sainio P. , Moore K. , Pehu E.
Published: March 2009

The phenotypic stability of seven Finnish and Nordic oat cultivars and 12 breeding lines developed at the Hankkija Plant Breeding Institute, Finland, was studied using the Finlay–Wilkinson regression method, Eberhart–Russell stability analysis, principal component analysis (PCA) with biplot presentation, canonical variate analysis (CVA) and Procrustes analysis. Comparison of stability analyses was based on four dissimilar growing seasons. In addition to the measurement of phenotypic stability of grain yield, the performance of 12 morpho-physiological traits was evaluated, including maturity class and structure of canopy and plant stand.

The different stability analyses examined produced uniform results and ranked the cultivars and breeding lines without major disagreements. Lines with exceptionally stable yield performance over the different growing seasons were identified. In general, there was an association of high yielding ability with poor stability. However, some cultivars deviated from this tendency and showed high grain yield production and average stability of yield performance.
Fate of35S-labelled urine sulphate in urine affected areas of pasture soil under field conditions
Authors: Williams P. H. , Haynes R. J.
Published: March 2009

The fate of35S-labelled sheep urine sulphate in the soil and its plant uptake were measured in field experiments over a 12 month period in 1990/91 in Canterbury, New Zealand. Urine was applied in either summer or winter. After the summer application, there was a marked increase in pasture growth and S uptake which lasted for a period ofc.90 days. Plant uptake of applied35S was very rapid andc.11% was recovered in the pasture herbage within 65 days of application. By the end of the experiment,c.80% had been recovered in the herbage. A portion of applied35S was incorporated into soil organic forms mainly as C-bonded S. After 86 days, 30% of the applied 35S was in the C-bonded form but during the rest of the experiment this declined to 17% as the35S was remineralized and absorbed by the growing pasture plants.

Following the winter urine application, the increase in pasture dry matter production and32S uptake was much less marked than that for the summer application. Twenty five percent of the applied35S was recovered in pasture herbage within 65 days and this increased to 70% by the end of the experiment. Some of the applied S was incorporated into soil organic forms and, by 83 days, 20% of the applied35S was present in C-bonded form. Through mineralization this declined to 7% by the end of the experiment. Over the initial 41 days of the experiment,c.25% of the35S was lost due to leaching.
Decision Support Systems for Profitable Livestock Production
Authors: Audsley E.
Published: March 2009

The Agricultural and Related Industries Study Group of the Operational Research Society held a one-day meeting on ‘Decision Support Systems for Profitable Livestock Production’ on 18 November 1992 at the Meat and Livestock Commission, Milton Keynes, UK. The Group promotes the use of the scientific method in solving management problems. The aim of the meeting was to look at the contribution of advances in modelling towards improving management and hence profitability in livestock production. The first four papers concerned feeding and the remaining two breeding. A large part of the discussion could perhaps best be summed up by the regression equation which related dry matter intake and waste output from a cow. When the output was zero, the intake was reduced by 50%!
Measurement of soil mineral nitrogen to predict the response of winter wheat to fertilizer nitrogen after applications of organic manures or after ploughed-out grass
Authors: Shepherd M. A.
Published: March 2009

In the autumns of 1985, 1986 and 1987, a total of 84 fields in England and Wales, which had received a recent dressing of organic manure or had recently been ploughed out of grass, was sampled to 90 cm depth to measure soil mineral nitrogen (Nmini.e. NH4-N and N03-N). Amounts of Nminvaried widely between sites, indicating the difficulty in estimating soil supply following ploughing grass or manure application although type of manure and Nminwere related. Soils contained much inorganic nitrogen where manures containing a large proportion of readily available N (pig slurry or poultry manure) had been applied. Where manures containing straw were applied, Nminwas greater in the second year after application than the first. The relationship between Nminand response of winter wheat to fertilizer was measured on 62 of the 84 sites sampled; there was no simple relationship between Nminand response to N. For fields just ploughed out of grass, the relationship was particularly poor. However, for fields with a history of arable cropping, there was no response to N fertilizer when Nminwas > 300 kg/ha N in either autumn or spring. Below this amount, response to fertilizer N varied considerably even for sites with similar amounts of Nmin. Nminmeasurements are of value in identifying soils containing sufficiently large N residues to allow fertilizer applications to be reduced, or even omitted, with confidence. Where residues are smaller, models need to be developed which take into account other factors, such as mineralization of organic nitrogen reserves, which modify nitrogen supply.
Growth responses in red deer calves and hinds grazing red clover, chicory or perennial ryegrass/white clover swards during lactation
Authors: Niezen J. H. , Barry T. N. , Hodgson J. , Wilson P. R. , Ataja A. M. , Parker W. J. , Holmes C. W.
Published: March 2009

Two experiments were conducted at the Massey University Deer Unit, New Zealand in 1990 and 1991 to evaluate the performance of lactating red deer hinds and their calves grazing conventional perennial ryegrass-based pastures, red clover or chicory. In both experiments, hind and calf performance was evaluated from 1 month post-parturition over a 2½ month summer period to weaning at 3½ months of age.

In Expt 1, hinds and calves were grazed on low (5·4 kg dry matter (DM)/hd/day), medium (10·8) or high (16·4) allowances of red clover, or on a medium allowance of a conventional ryegrass/white clover sward (9·9 DM/hd/day). In Expt 2, hinds and calves grazed equal DM allowances (12 kg DM/hd/day) of perennial ryegrass/white clover, chicory or red clover.

Red clover generally had higher organic matter digestibility (OMD) and higher total N than ryegrass/white clover, and when grazed at equal DM allowances, promoted higher voluntary food intake in the hinds, increased calf growth (430v.330 g/day) and increased hind liveweight change. Although decreasing the red clover allowance in Expt 1 slightly but non-significantly decreased hind voluntary food intake and decreased both calf and hind liveweight change, all low red clover values were still consistently higher than all ryegrass/white clover values (P < 0·05). In Expt 2, chicory was of higher OMD and ash content than red clover but N content was lower and similar to ryegrass/white clover. Chicory promoted lower levels of calf liveweight change than red clover but higher than ryegrass/white clover. Hind liveweight change on chicory was lower than on red clover and was similar to ryegrass/white clover. It was concluded that red clover offers potential as a special purpose forage for deer production and that further experimental work is needed with chicory.
Quantitative carbon distribution in clonal plants of white clover (Trifolium repens): source-sink relationships during undisturbed growth
Authors: Chapman D. F. , Robson M. J. , Snaydon R. W.
Published: March 2009

The assimilation and distribution of carbon in laterally spreading white clover plants was quantified in a controlled environment using CO2exchange rate measurements and14C as a tracer. Plants were restricted to three mature leaves on the main stolon apex, and the movement of14C from these leaves (and one immature, but carbon-exporting, leaf) to meristematic zones throughout the plant was determined by detailed plant dissection.

Sinks throughout the plant drew small to moderate proportions (typically 1–8%) of the14C exported by all mature leaves. The three mature leaves displayed similar export patterns, and no specific source-sink relationships involving any of these leaves were observed. However,14C exported by the developing leaf moved predominantly to the main stolon apex, and to adjacent young stolon tissue. Estimated respiratory losses over 24 h accounted for 40–49% of the 14C fixed. Of the total amount of C exported by all four leaves and utilized in new growth or reserve storage, 22% moved to the main stolon apex, 16% to stolon tissue of the main stolon, 34% to adventitious roots on the main stolon (most of which was utilized in older, nodulated roots) and 29% to branches. The apex received the greatest amount of C/unit weight, reflecting its high sink activity, its proximity to the source leaves and, possibly, apical dominance. Subtending leaves provided 46–51% of the C utilized by young branches. Older branches continued to import significant quantities of C from parent stolon leaves despite having their own C sources, though parental support for branches was seen to decrease as branches aged, when the quantity of C they imported was expressed as a function of their weight.

Relative sink strength and distance between sources and sinks contributed to the observed patterns of C distribution. No apparent restriction on C movement was imposed by the vascular architecture of stolons.
An evaluation of the minirhizotron technique for estimating root distribution in potatoes
Authors: Parker C. J. , Carr M. K. V. , Jarvis N. J. , Puplampu B. O. , Lee V. H.
Published: March 2009

The minirhizotron technique was evaluated for estimating root length density in potatoes (Solanum tuberosum‘Record’) by comparing observations in angled 45° glass tubes with corresponding root length densities obtained by (a) destructive core sampling, and from (b) counts of root tips on the soil face of excavated trenches. Measurements were made in a field experiment in Bedfordshire, UK, in 1985, with shallow and deep cultivation as variables, and in a glasshouse trial.

Only at depths below 0·3 m did root lengths observed with minirhizotrons reflect at all closely those estimated from core sampling and even then there was a tendency to overestimate root density. In the surface cultivated layers, where 80–90% of the total root length was present, results from minirhizotrons were unreliable, probably because of poor soil–tube contact and, in soils which shrink on drying, preferential root growth at the interface between the soil and the glass.

Minirhizotrons can provide a realistic estimate of the rate of root growth of potatoes with depth over time when compared with maximum depths of water extraction, but appear to be unreliable for providing a quantitative measure of total root length density.
Simplified rotational grazing management of dairy cows: effects of rates of stocking and concentrate
Authors: Hoden A. , Peyraud J. L. , Muller A. , Delaby L. , Faverdin P. , Peccatte J. R. , Fargetton M.
Published: March 2009

An experiment was carried out in Normandy between 1986 and 1988 over c. 6 months in each year, using a simplified rotational grazing technique (two paddocks in spring, four in autumn) with a total of 162 high-yielding cows (mean milk yield of 30·0 kg/day at turn-out). Three stocking rates, designated control (C: 2·3 cows/ha over the total area of the system), moderate (M: 2·6 cows/ha = 115% of C) and high (H: 3·0 cows/ha = 130% of C), were compared at two rates of concentrate supplement, 3·7 kg/cow per day and 0·5 kg/cow per day. Individual milk yield differed by a non-significant 5% between the extreme stocking rates (21·3 v. 20·3 kg fat-corrected milk (FCM) for treatments C and H, respectively). Milk production/ha was 23% greater in the H treatment (9816 v. 7970 kg FCM for H and C, respectively). Concentrate supplementation led, on average, to a 9% milk yield improvement (21·8 v. 20·0 kg FCM for high and low rates, respectively), i.e. a mean efficiency of 0·6 kg FCM/kg supplement. This response tended to be greater in the higher-yielding cows and for the high stocking rate. The sward measurements contributed to a better understanding of herbage utilization by the cows.
Grouping and complete diet composition in relation to parity and potential yield in dairy cows
Authors: Kroll O. , Owen J. B. , Whitaker C. J.
Published: March 2009

Three experiments, involving a total of 294 Israeli Holstein cows, were carried out to study aspects of the grouping of cows in relation to timing of changes and the type of complete diet given. In Expt 1, 40 cows were changed from a high energy diet to a medium energy diet either at 60 or at 180 days post calving. The results indicated a larger reduction in milk and FCM yield following the later than the earlier change of diet.

Experiment 2 involved 64 cows subjected to two treatments, one involving a ‘uniform’ diet (25:75 forage to concentrate D.M. ratio) and the other a ‘step’ treatment where the same diet as in treatment 1 was given for approximately 74 days and then changed to a diet of 35:65 forage to concentrate ratio. The results showed that it is not necessary to adopt different feeding systems according to the potential yield of the cow and that cows could be given rather lower energy diets within the range offered without loss of efficiency.

In Expt 3, involving 190 cows, the cows were divided into one of two feeding treatments, ‘uniform’ and ‘step’ similar to Expt 2 and the effect of potential yield and parity was considered. The results emphasized the importance of potential yield rather than feeding system in relation to yield. The results showed a shorter period from calving to conception for the ‘uniform’ treatment.

A strategy for efficient cow feeding is outlined.