bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of strategic use of fertilizer nitrogen in spring and/or autumn on the productivity of a perennial ryegrass/white clover sward
Authors: FRAME J. , BOYD A. G.
Published: April 2006

The productivity of a mixed sward, comprising perennial ryegrass cvs Barlano and Bastion and white clover cvs Donna and Aran, was measured under sixteen fertilizer N treatments. These involved 0.25, 50 and 75 kg N ha‐1 in spring only, in autumn only and in all combinations of spring N and autumn N. A simulated grazing regime of six cuts annually at 3‐ to 6‐week intervals was imposed.

Increasing rates of total N application increased total herbage DM regardless of application pattern. Yield response was greater with N applied in the spring, and total herbage DM was higher with high spring N‐low autumn N than the reverse. Mean yield responses at the first harvest to 25, 50 and 75 kg ha‐1 N in spring were 13.6, 10.8 and 11.6 kg DM per kg N. Corresponding responses at the final harvest to N rates in the autumn were 7.2, 5.8 and 6.8 kg DM per kg N. Responses were similar at these times for treatments receiving combined spring and autumn N.

Over all treatments, mean annual production of total herbage was between 7.08 t ha‐1 DM with no N and 8.19 t ha‐1 with 75 kg ha‐1 N in both spring and autumn. Owing to drought, mean production in year 2 fell by 32% compared with year 1.

White clover production fell progressively with increasing N application. Treatments with spring‐applied N gave the most marked decrease. White clover was more markedly depressed than the associated grass by the drought in the second year. The mean reductions in white clover content were 0.17, 0.07 and 0.12 percentage units per kg applied N for spring N, autumn N and combinations. Autumn N use depressed white clover less than spring N but the yield response of grass was less.

It is concluded that any applied N adversely affects white clover performance to some degree. Where management factors are unfavourable to white clover even strategic N use may not be wise. Instead, it is suggested that a ‘dual‐sward’ approach be adopted in practice, namely, grass/white clover swards with no N. and complementary grass swards receiving optimum applied N to give better production at times when grass/white clover swards are relatively less productive.
The effect of cereal incorporation on the fermentation of spring‐and autumn‐cut silages in laboratory silos
Authors: JONES D. I. H.
Published: April 2006

The effect of adding ground oats and barley on the ensiling characteristics of autumn‐and spring‐harvested ryegrass was studied in laboratory scale silos.

The addition of oats or barley at rates of 13 or 53 kg t−1 of grass significantly improved the fermentation of late autumn ryegrass silage in the first year. Ammonia N levels were reduced from over 20% of total N to 11% or less. Similar addition to autumn‐cut ryegrass higher in soluble carbohydrate content in the second year also significantly reduced pH and ammonia levels but all silages were well fermented. Addition of cereals to spring‐cut ryegrass containing over 20% soluble carbohydrate had no effect on fermentation. Cereal addition increased silage DM and decreased silage fibre content in all experiments.

The results are discussed in relation to the potential advantage of cereal addition in the ensiling of grass crops.
Changes in mass and chemical composition of grass roots during decomposition
Authors: LARSSON K. , STEEN E.
Published: April 2006

The decomposition of dead roots of perennial grasses was examined in nylon litter bags not containing soil at two soil depths, 10 and 20 cm, and also in larger nylon bags containing soil at 020 cm depth. Bags were sampled three times during the growing season to determine weights of organic matter, crude protein, Klason lignin and non‐structural and structural carbohydrates.

From 3 July to 5 October (94 days) the litter bags at 10 and 20 cm and the nylon bags lost, respectively, 35,38 and 65% of their organic mass of particle size < 1 mm.

Non‐structural carbohydrates constituted 6% of the organic matter in the original sample but only 1% or less during the sampling period. Klason lignin increased from 22 to 29% and crude protein from 8 to 10% of the remaining organic matter, whereas structural carbohydrates changed very little.

The constituents were degraded at different rates. The non‐structural carbohydrates had decomposed almost completely by the first sampling and of the other constituents the structural carbohydrates were degraded most rapidly. Before the first sampling unexpected amounts of structural carbohydrates, particularly glucans, had disappeared.

The results help to explain rapid declines in root mass (up to 50%) during summer in perennial grass leys observed in earlier experiments.
Effects of supplementation on the ingestive behaviour of grazing steers*
Authors: DOUGHERTY C. T. , FORBES T. D. A. , CORNELIUS P. L. , LAURIAULT L. M. , BRADLEY N. W. , SMITH E. M.
Published: April 2006

Herbage intake is usually depressed when beef cattle grazing abundant pastures are supplemented with energy‐rich feedstuffs but relatively little is known about the effects of supplementation on the components of ingestive behaviour. An experiment was conducted to establish the effect of ground corn (Zea mays L.) on the ingestive behaviour of yearling Angus and Angus × Hereford steers (Bos taurus) (mean live weight (LW) of 323 kg) grazing autumn stockpiled Boone cocksfoot (Dactylis glomerata L.) using a tethered grazing system in which the experimental unit was the tethered steer and its grazing area (45 m2) for one grazing session. Herbage dry matter (DM) mass was 1662 kg ha−1 and herbage DM allowance was 7–5 kg steer−1 for each grazing session. Herbage DM intake was measured as the difference between herbage DM mass offered and refused. Grazing took place during two daily sessions each of about 2 h duration commencing at 08.00 and 14.00 h for 9 days. Ground corn (0, 1·5, 3·0 and 4·5 kg steer−1) was fed each day at 12.00 h and had no significant (P < 0·05) effect on rate of DM intake, rate of biting or DM intake per bite. Mean DM intake was 6 2 kg steer−1 d−1 (87 mg (kg LW)−1 min−1). Steers averaged 4832 bites per grazing session, with a mean DM intake per bite of 644 mg (2·0 mg (kg LW)−1) and a mean rate of 44 bites min−1. Data obtained at the beginning and end of each grazing period on ingestive behaviour of one group of four steers (mean LW of 306 kg) fitted with oesophageal fistulae supported data for the two groups of normal steers and showed no response to supplementation. Mean values for rate of DM intake, DM intake per bite and rate of biting established for the fistulated cattle were 73 mg (kg LW)−1 min−1, 521 mg bite−1 (1·7 mg (kg LW)−1) and 39 bites min−1, respectively.
The effect of fasting on short‐term cattle grazing behaviour
Authors: GREENWOOD G. B. , DEMMENT M. W.
Published: April 2006

The effects of fasting on feeding behaviour, intake rates, and diet quality were studied with steers grazing vegetative Lolium multiflorum swards. Fasting interrupted the normal alternation of grazing and rumination and led to longer grazing times (0·65 vs. 0·45 of observed time), shorter rumination times (0·15 vs. 0·30 of observed time), and higher total dry matter (DM) intakes (6200 g DM vs. 3750 g DM d−1)‐Fasting did not affect prehended bite size which averaged 047 g DM bite−1. Declining bite size within a day was explicable by changes in herbage mass. Biting rate (38.9 bites min−1) and instantaneous intake rate (2675 g DM min−1) of fasted animals were considerably higher than non‐fasting animals in the mornings, but neutral detergent fibre (NDF) concentration of the diet (0 742 of organic matter) was generally not depressed by fasting. Consequently, non‐fasted animals appeared to be feeding suboptimally since their nutrient intake rates were considerably lower than that which they are capable of exhibiting. Mastication rates per unit NDF intake were considerably lower in the morning for fasted animals (0·78 chews g−1 NDF intake) which suggested that their intake rates may have led to larger ingested particle size. Therefore, on Lolium multifiorum swards, the steers attained a higher intake rate by masticating the forage less while maintaining diet quality.
Herbage growth and utilized output from grassland on dairy farms in southwest England: case studies of five farms, 1982 and 1983. I. Herhage growth
Authors: PEEL S. , MATKIN ELIZABETH A. , HUCKLE C. A.
Published: April 2006

Herbage growth was measured in two contrasting years on five farms representing a range of soil types. On fields cut for conservation in 1982 DM production varied between farms from 12.3 tha‐1 to 14.1 tha‐1 in line with fertilizer N levels, which ranged from 220 to 333 kg ha‐1. In 1983 production was from 10.3 tha‐1 to 12.3 tha‐1; this again corresponded with fertilizer N, except on farm B which had the shallowest soils. On fields used for grazing all farmers used rotational management. Herbage accumulation was measured by trimming to 25 mm and harvesting after 4 weeks. As on conservation fields, herbage accumulation was generally greater on farms using more N, at least up to 300 kg ha‐1.

In 1982 growth consistently exceeded predictions based on plot experiments. In 1983 growth was on average less than predicted on grazing fields but slightly more than predicted on cutting fields‐We conclude that such predictions of annual production are a valuable aid to farm planning, and need not be reduced to allow for on‐farm conditions, although they are least good at low levels of N. Predictions of individual cuts were not satisfactory, with a strong tendency to overestimate first cut and underestimate second cut.

There was no indication that annual herbage production was less on badly drained than on well drained soils. Indeed, in the dry summer of 1983 badly drained land appeared to have an advantage, despite considerable poaching damage in the spring. Furthermore, there was no evidence that production was deficient on swards dominated by Holcus and Agrostis spp.
The influence of tall fescue on the germination, seedling growth and yield of birdsfoot trefoil
Authors: STEPHENSON R.J. , POSLER G.L.
Published: April 2006

The influence of tall fescue (Festuca arundinacea Schreb.) on germination and seedling growth of birdsfoot trefoil (Lotus corniculatus L.) was evaluated during 1983‐85 at Manhattan, Kansas. Studies were designed to evaluate tall fescue cv. Kentucky‐31 for possible allelopathic compounds, determine the effects of tall fescue on the germination, seedling growth and yield of birdsfoot trefoil, and to characterize the chemical properties of tall fescue. Fescue produced allelopathic compounds, particularly during the spring and autumn months when it was actively growing. The greatest trefoil inhibition occurred with fescue plant extracts prepared during the autumn (September and October). The concentration of fescue extracts influenced trefoil germination, with greater inhibition as fescue concentration increased. In a sand medium under greenhouse conditions, fescue extracts prepared in spring and autumn reduced trefoil growth by 50 and 56%, respectively, with no inhibition during the summer months. Under field conditions, full strength fescue extracts reduced trefoil plant populations by 14 and 57% with spring and autumn prepared extracts, respectively. Fescue competition reduced sod‐seeded trefoil plants per unit area by 17 and 31% for spring and autumn seeding, respectively. Full strength fescue extracts reduced trefoil seedling growth by an average of 37%, and trefoil dry matter yields by 53%.
Particle size reduction of the leaves of a tropical and a temperate grass by cattle
Authors: WILSON J. R. , McLEOD M. N. , MINSON D. J.
Published: April 2006

This study investigates forage particle breakdown, which is a factor of potential importance for the low intake of forages, particularly tropical grasses. A comparison was made between fresh leaf blades of a tropical grass, green panic (Panicum maximum var. trichoglume) and a temperate grass, Italian ryegrass (Lolium multiflorum). Leaf blades were chopped into 50 mm lengths and fed to cattle with oesophageal and rumen fistulae. Particle size was assessed on chewed samples immediately after eating and after digestion for 6, 12, 24, 48, 96 h and 3 weeks in nylon bags in the rumen.

Chewing during eating reduced particle size more in length than in width and more in green panic than in ryegrass. Mean length was decreased 9·2‐fold and 4·7‐fold for the two species respectively, and mean width 5·4‐fold and 2·3‐fold. Green panic leaf had a higher cell wall content and higher dry matter content than ryegrass leaf.

Digestion caused a substantial reduction in the width of the particles but not in the length. Width reduction occurred more rapidly in the ryegrass which was reduced to narrow fibres within 12–24 h of digestion while in green panic the same extent of degradation took < 48 h. After 96 h digestion, mean width of the chewed material had been reduced 40‐fold in ryegrass compared with only 165‐fold in green panic; all particles of both species were < 1 mm in diameter. The mean length of particles after 96 h digestion was similar to that of the chewed feed. Ryegrass was more digestible than green panic, a difference of 150 g kg DM−1 which was maintained from within the first 6 h of digestion up to 96 h digestion. After three weeks the digestibility of ryegrass was c. 50 g kg DM−1 higher than that of green panic but the proportion of cell wall that was ultimately indigestible was the same (0465) for both species.
The relationship between spoilage and Listeria monocytogenes contamination in bagged and wrapped big bale silage
Authors: FENLON D. R. , WILSON J. , WEDDELL J. R.
Published: April 2006

A farm‐scale trial to compare the effectiveness of polythene bags and wrapping of big bale silage was monitored for Listeria monocytogenes contamination. There was no significant difference between the level of L. monocytogenes found in wrapped and bagged big bale silage, but the work confirmed that big bale silage is prone to contamination by Listeria organisms, and that the degree of Listeria contamination could be significantly reduced by the removal of obviously spoiled material prior to feeding.
Evaluation studies in the development of a commercial bacterial inoculant as an additive for grass silage
Authors: STEEN R. W. J. , UNSWORTH E. F. , GRACEY H. I. , KENNEDY S. J. , ANDERSON R. , KILPATRICK D. J.
Published: April 2006

A randomized‐block experiment was carried out to evaluate a bacterial inoculant, based on a single strain of the organism Lactobacillus plantarum, as a silage additive. The inoculant‐treated silage was compared with untreated and formic acid‐treated silages. The three silages were harvested from a perennial ryegrass sward on 30 September and 1 October, 1985 using two double‐chop forage harvesters. Formic acid (850 g kg−1) was applied at a rate of 31t−1 and the inoculant at a rate of 3 g mixed in 31 water t−1 (1 × 106 colony forming units (g grass)−1). The dry matter and water‐soluble carbohydrate contents of the grass at ensiling were 165 g kg−1 and 18·9 g kg−1 respectively. For a period of 84 d, the three silages were offered ad libitum and supplemented with three concentrates in a 3 × 3 factorial design to 63 male cattle which were initially 15 weeks old and 128 kg live weight. The three concentrates were (1) barley (115 g crude protein (CP) (kg DM)−1), (2) barley/soyabean meal (207 g CP (kg DM)−1) and (3) barley/fish meal (200 g CP (kg DM)−1); each was offered at a mean rate of 1·7 kg d−1. For the untreated, formic acid‐treated and inoculant‐treated silages respectively, ammonia‐N concentrations were 162, 91 and 176±60 g (kg total N)−1; pH's were 4·48, 3·89 and 4·45±0·046; butyric acid contents were 12·1, 1·3and 16·6g(kg DM)−1; metabolizable energy contents were 12·4, 12·2 and 1·23±0·29 MJ (kg DM)−1; silage DM intakes were 2·28, 2·49 and 2·44±0·037 kg d−1 and liveweight gains were 0·90, 0·95 and 0·97±0·023 kg d−1. For the barley, barley/soyabean meal and barley/fishmeal supplements respectively, silage DM intakes were 2·29, 2·43 and 2·49 ± 0·037 kg d−1 and liveweight gains were 0·87,0·97 and 0·99 ±0·023 kg d−1. There were no significant interactions between silage type and the supplement offered. It is concluded that silage fermentation and metabolizable energy contents were similar for the untreated and inoculant‐treated silages but that silage dry matter intake and liveweight gain were significantly greater for the inoculant‐treated than for the untreated silage. Further work is needed to elucidate the mode of action of this type of silage additive.
A forage dynamics model for use in range or pasture environments
Authors: BLACKBURN H. D. , KOTHMANN M. M.
Published: April 2006

A deterministic model that simulates forage dynamics is described and validation results presented. The model simulates different species of grasses and forbs for a production year and provides the necessary input for a diet selection model. The model does not simulate growth, but does simulate the accumulation of live leaf and stem, the senescence of live biomass, and its transfer to dead mass using growth rates for leaf and stem of each species, which are specified for the model. Using such an approach specific types of years can be simulated. Plant components in the model include live leaf and stem, dead leaf and stem, and old dead leaf and stem which were produced during the previous growing season. These plant components were chosen because of their importance in the diet selection process and their differences in forage quality. Plant species which the model was validated against were Cynodon dactylon, Avena sativa. Schizachyrium scoparium and Paspalum plicatulum. Validation results indicated that with adjustment to input growth rates, live biomass could be adequately simulated. Deviations between measured and simulated dead components were observed for S. scopariumand P. plicatulum.High values observed for dead stem early in the trial resulted from lack of separation of dead and old dead stem material in the field sampling. Variations in dead forage throughout the season were caused by unexplained sources of variation. This indicated a need for field research to better quantify the dynamics of dead biomass. The model meets its goal of simulating biomass dynamics and forage quality of plant parts and it provides a suitable forage base to interface with diet selection and animal simulation models.
Short‐term fasts and the ingestive behaviour of grazing cattle
Authors: DOUGHERTY C. T. , BRADLEY N. W. , CORNELIUS P. L. , LAURIAULT L. M.
Published: April 2006

Twelve tethered Angus cows (Bos taurus)weighing 471 ± 18 kg were used in a balanced changeover design to estimate the direct (D), residual (R), and permanent (P) effects of 1,2, and 3 h fasts following 2 h grazing sessions on the ingestive behaviour of cattle grazing swards of endophyte‐(Acremonium coenophialum Morgan‐Jones and Gams)‐free tall fescue (Festuca arundinaceaSchreb. cv Kentucky 31) (Exp I) and lucerne (Medicago sativaL. cv Arc) (Exp II). Herbage dry‐matter (DM) mass (> 5 cm) and individual herbage DM allowances were 1‐16 t ha‐1 and 50 kg per hour in Exp I and 1‐861 ha‐1 and 78 kg per hour in Exp II, respectively. In Exp I, P effects of fasting followed trends of R effects since the D effects were small. Mean DM intake rates (P) were 2‐2., 1‐8, and 1‐3 kg h‐1 for cows given 1, 2, and 3 h fasts, respectively. Mean intakes (DM) per bite (P) were 082, 071, and 045 g bite‐1 for cows assigned 1, 2, and 3 h fasts, respectively. Rates of biting were not affected by fasting and averaged 45 bites min”’. In Exp II, P effects followed trends in D effects since R effects were small. Mean DM intake rates (P) were 20, 22, and 3‐0 kg for cows subjected to 1,2, and 3 h of fast, respectively. Rates of biting (P) were 24, 27, and 32 bites min‐1 for cows after 1, 2, and 3 h fasts, respectively. DM intakes per bite (P) were not affected by fasts and averaged 1‐46 g bite‐1. The behavioural responses of cattle to interval between meals were attributed to differences in flow characteristics of ingesta of lucerne and tall fescue in the gastrointestinal tract.
The use of irradiation for the preservation of fresh herbage for subsequent botanical and chemical analysis
Authors: TALLOWIN J. R. B. , BROOKMAN S. K. E.
Published: April 2006

The use of irradiation as a means of preserving fresh forage for subsequent botanical and chemical analysis was examined as a possible alternative to preservation by freezing. Forage samples containing a mixture of grass species were given irradiation doses of either 2‐5 Mrad (25 k Grays) or 5‐0 Mrad (50 k Grays). These samples were then stored in the dark under either ambient or chill (+ 2°C) conditions for up to 5 months, while similar samples of fresh forage were stored over the same period deep frozen at — 15°C. No spoilage or signs of any subsequent senescence were observed in the forage given the 5‐0 Mrad irradiation treatment during the 5 month storage period. In the 2‐5 Mrad treated material some browning of lamina tips occurred. However, the irradiation treatment did cause some colour changes, mainly a darkening of the green tissue. The state of preservation was also assessed by measuring the rate at which stored herbage could be separated into the constituent species. No difference in separation rates was found between samples that had either been stored frozen or irradiated at 5‐0 Mrad (and then stored under either ambient or chill conditions); however, separation rates were slower on the 2‐5 Mrad treated samples. The irradiation treatment did not cause any significant change in percent nitrogen content. However, water‐soluble carbohydrate contents in the irradiated samples were significantly lower. The cost of commercial irradiation treatment was less than 20% of the commercial cost of freezing and cold storage.
Prediction of lactic acid bacterial numbers on lucerne
Authors: MUCK R. E.
Published: April 2006

The numbers of lactic acid bacteria (LAB), as measured by Rogosa SL agar, on lucerne (Medicago sativa) chopped for ensiling were predicted using two methods. The first prediction method consisted of regression equations developed from two previous harvesting seasons and required inputs of wilting time between mowing and chopping, average wilting temperature and moisture content of the lucerne at chopping. The second method simulated the growth of LAB on the lucerne during wilting and needed similar inputs. The former method predicted LAB counts within one order of magnitude more than 95% of the time except for lucerne samples drier than 60% dry matter. The prediction of the simulation model had more variation than those of the regression equations, but the simulation model was applicable over a wider range of conditions. These results, together with earlier studies, provide a preliminary basis for determining when a silage inoculant containing LAB will be most beneficial.
Agricultural intensification and the loss of habitat, species and amenity in British grasslands: a review of historical change and assessment of future prospects†
Authors: GREEN B. H.
Published: April 2006

Grassland in Britain is a plagioclimax vegetation type. All lies on land originally cleared from forest and, without some form of management, would revert to forest through a process of natural succession. Traditionally managed, unsown grasslands nonetheless resemble more natural grasslands in other parts of the world and contain a substantial proportion of our native flora and fauna. They are also often important for recreational activities. Agricultural intensification over a long period has led to a loss in their extent, species and amenity. Reconciling agricultural and environmental objectives in grassland management is very difficult because increased fertility and production invariably leads to species loss. Current overcapacity in the agricultural industry is leading to the switching of some agricultural support from food production to countryside management. As a result some arable and intensively managed grass is being managed more extensively. However future production technologies may be so efficient that very many fewer stock are required with the result that much marginal grassland may revert once again to forest.
Response of permanent and reseeded grassland to fertilizer nitrogen. 1. Herbage production and herbage quality
Authors: HOPKINS A. , GILBEY J. , DIBB C. , BOWLING P. J. , MURRAY P.J.
Published: April 2006

The productivity of permanent swards of mixed species composition was compared with that of sown Lolium perenne, cv. Melle at five fertilizer‐N rates (0, 150, 300, 450 and 900 kg N ha−1) and with L. perenne/Trifolium repens, cv. Grasslands Huia at 0 kg N ha−1. The investigation was conducted under two cutting frequencies at sixteen sites in England and Wales, representing a range of grassland environments.

Annual total herbage dry matter (DM) production from both permanent and reseeded swards increased with successive increments of fertilizer‐N up to 450 kg N ha−1. Herbage DM production from reseeded swards in the first year after sowing was signficantly higher than from the permanent swards, at all fertilizer‐N treatments. In subsequent years the production advantage of the L. perenne reseeds was maintained only at the higher N rates, though sown L. perenne/T. repens was the most productive sward type at 0 N. Average differences in modified acid‐detergent fibre suggested small advantages in herbage quality to the reseeded swards.

It is concluded that, while reseeded swards are more productive in the year after sowing, many permanent swards are capable of high levels of production and that reseeding to a L. perenne sward cannot always be justified, particularly for grassland receiving low or moderate inputs of fertilizer‐N.
Moderation of ingestive behaviour of beef ca le by grazing‐induced changes in lucerne swards†
Authors: DOUGHERTY C. T. , COLLINS M. , BRADLEY N. W. , CORNELIUS P. L. , LAURIAULT L. M.
Published: April 2006

Intensive grazing of pastures may cause drastic and rapid changes in swards which have major effects on ingestive behaviour and diet. Twelve adult Angus cows (Bos Taurus), mean live weight of 482±19 kg, were allowed to graze on swards of lucerne (Medicago sativa L.) that were not grazed (TO), or had been grazed previously for 1 h (T1), or 2 h (T2) in a balanced changeover design. Herbage dry ma er (DM) masses (>5 cm) were 2611, 1895 and 1441 kg ha−1; leaf fractions were 0‐48, 0‐29 and 0‐14; and herbage DM allowances per animal were 10·6, 7·9 and 6·0 kg h−1 for TO, T1 and T2, respectively. During a 1 h measured grazing session that followed an overnight fast, cows ingested 2‐93, 1·71 and 0·66 kg DM h−1 with herbage DM intakes per bite of 1·6, 0·9 and 0·4 g for T0, T1. and T2, respectively. Rates of biting did not respond to sward treatment and averaged 30 bites min−1. Intake of leaf DM was estimated at 98, 70 and 6% of total DM intake for the same treatment sequence. Utilization of herbage allowance was 0·29, 0·23 and 0·12, for TO, T1 and T2, respectively. Metabolzable energy (ME) intake per animal was 30, 17 and 5 MJ h−1 and ME intake per bite was 16, 9 and 3 KJ for TO, T1 and T2, respectively. Data show that grazing‐induced differences in sward characteristics moderate both ingestive behaviour and diet.
Growth of grass/clover mixtures during winter
Authors: WOLEDGE JANE , TEWSON VERONICA , DAVIDSON I. A.
Published: April 2006

The percentage of clover in a mixture of Huia white clover and Melle perennial ryegrass decreased during each of three winters. In the most severe winter, both grass and clover suffered a net loss of weight, clover losing two–thirds of its maximum weight while grass lost about one–third. In the mildest winter, grass continued to gain weight throughout, while clover lost weight. Such losses, when combined with conditions such as the use of nitrogen fertilizer, which prevent a recovery of clover percentage during summer, will lead to a long–term decrease in the clover content of a sward.

The losses from the clover were contributed to by all plant parts especially leaf, which lost between 60% and 95% of lamina weight. The change from autumn to winter caused a greater decrease in the number of live leaves per shoot. and in the area and weight of individual leaves, in clover than in grass. Other work has shown that there is a greater decrease in photosynthesis in clover than in grass, probably owing to changes in canopy structure; this is one cause of clover's poor performance, though differences between the two species in the effect of winter on the distribution of the carbon fixed in photosynthesis and in losses of weight in respiration and tissue death may also be involved.
The effect of cell wall degrading enzymes or formic acid on fermentation quality and on digestion of grass silage by cattle
Authors: JAAKKOLA S. , HUHTANEN P. , HISSA K.
Published: April 2006

A first cut of timothy, treated with water (untreated), formic acid (FA), cellulase + lactic acid bacteria (CB), cellulase + hemicellulase (CH) or cellulase + hemicellulase + a lignin‐modifying enzyme (CHL), was ensiled in pilot‐scale silos. Silages, except CB, were fed to four male cattle, each equipped with a rumen and duodenal cannula, in a digestibility trial designed as a 4 × 4 Latin square. The animals were fed a diet of 400 g of concentrate and 600 g of silage at a level of 70 g DM kg−1 live weight (LW0·75).

All enzyme‐treated silages were well‐preserved with a more extensive fermentation than in FA silage. The quality of untreated silage was poorer as indicated by higher pH and ammonia‐N content. The amount of effluent from enzyme‐treated silages ranged from 116 to 127 g kg−1; for FA and untreated silages values were 101 g kg−1 and 80 g kg−1, respectively. Total DM losses from enzyme‐treated silages were higher than from FA silage (P < 0·05). No significant differences were noticed between silages in the apparent digestibility of organic matter (OM), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF) or nitrogen (N). The apparent digestibility of cellulose was higher with enzyme‐treated silages than with FA silage (P < 0·05). The values for microbial N flow at the duodenum were 80·0, 91·9, 80·7 and 70·5g N d−1, and for the efficiency of rumen microbial N synthesis 38·6, 47·6, 36·9 and 32·5 g N kg−1 OM apparently digested in the rumen for untreated, FA, CH and CHL silages, respectively. In the rumen the molar proportion of propionate was higher (P < 0·01) and that of butyrate lower (P < 0·01) with enzyme‐treated silages when compared with FA silage. The proportion of butyrate was also lower with untreated than with other silages (P < 0·01). The rumen residence time of NDF and ADF was longer (P < 0·05) with enzyme‐treated silages than with FA silage.
Sources of error with in vitro digestibility assay of pasture feeds
Authors: AYRES J. F.
Published: April 2006

A series of experiments was undertaken to determine population statistics for in vitro organic matter digestibility (in vitro OMD) data and to examine the effects of basal diet, donor animal and precollection fasting interval on the activity and specificity of rumen fluid inoculum. The experiments utilized wether sheep, a diverse set of pasture grass and legume feeds prominent in the Australian subtropics and the Tilley and Terry in vitro digestibility procedure running under the operating pressure of a practicing feeds evaluation laboratory.

The standard errors of in vitro OMD estimates for within and between batch runs were ±0·88 × 10−2 and 0·62 × 10−2, respectively. These error terms were used to develop protocols to accept, reject or scale raw in vitro OMD data. Differences between donor animals in the activity of rumen fluid were highly significant. Extending the precollection fasting interval beyond 16 h was associated with a substantial decline in inoculum activity.

An in vitro‐in vivo calibration relationship based on fifteen test feeds and using lucerne (Medicago sativa) as basal diet was described by the linear model y = 1·3 x‐0·195±4·9 × 10−2r= 0·79 (y =in vivo OMD, x =in vitro OMD). Despite large effects of basal diet on both the absolute values and relative ranking of test feeds, neither the RSD nor r values were improved using alternative diets to Lucerne chaff.

The results highlight the need to formally standardize the analytical and biological components of the in vitro digestibility procedure to safeguard the integrity of data.
Slug density‐seedling establishment relationships in a pasture renovated by direct drilling
Authors: BARKER G. M.
Published: April 2006

Ryegrass and white clover were sown singly or in combination at various seeding rates by direct drilling into plots in which a range of slug densities had been established by molluscicide baiting. For both ryegrass and white clover, weights of individual seedlings and numbers and yields of seedlings per metre of drill row were significantly affected by slug density, ryegrass seed rate, clover seed rate and interactions of these factors. Plant losses increased asymptomatically with slug density, indicating higher rates of seedling destruction per slug at low slug densities.
Herbage production and quality of a range of secondary grass species at five rates of fertilizer nitrogen application
Authors: FRAME J.
Published: April 2006

The productivity of ten grasses was measured under six cuts per annum for 3 years and three cuts for a fourth harvest year in comparison with a perennial ryegrass (Lolium perenne) control. The grasses were Yorkshire fog (Holcus lanatus), two red fescues (Festuca rubra), creeping bent (Agrostis stolonifera), bent (Agrostis castellana), bent (Agrostis capillaris), smooth meadow‐grass (Poa pratensis), crested dogstail (Cynosurus cristatus), sweet vernal (Anthoxanthum odoratum) and timothy (Phleum bertolonii). Another grass sown, rough meadow‐grass (Poa trivialis), did not persist after the first harvest year. Annual N rates were 0, 120, 240, 360 and 480 kg ha−1.

Classified by DM production, the grasses grouped into: high (perennial ryegrass, Yorkshire fog and red fescue), intermediate (creeping bent, bent (A. castellana), crested dogstail and smooth meadow‐grass) and low (bent (A. capillaris), sweet vernal and timothy. With frequent cutting, production ranking interacted with N rate: Yorkshire fog. red fescue and creeping bent were more productive than ryegrass at the 0 N and 120 N rates but not at higher N rates; crested dogstail and sweet vernal outperformed ryegrass at 0 N; ryegrass and smooth meadow‐grass performed relatively better at moderate to high N. DM production of ryegrass was matched or exceeded by some of the other grasses during different parts of the season particularly at low N rates. Notable features from the 3‐cut regime were the outstanding DM production of Yorkshire fog at all N rates and the poor production of bent (A. capillaris) and crested dogstail. High DM response to applied N in both cutting regimes was given by perennial ryegrass. smooth meadow‐grass, red fescue cv. Boreal, timothy, crested dogstail and Yorkshire fog.

N concentrations were highest in less productive grasses such as the bents and lowest in highly productive ryegrass and Yorkshire fog. Ryegrass was superior in digestibility to the other grasses, but especially to the red fescues, bents and smooth meadow‐grass. The other grasses, especially Yorkshire fog and bent (A. capillaris) were superior to ryegrass in P, K and Mg concentrations, but not Ca.

It is concluded that the annual and/or seasonal production of some of the secondary grasses at low to moderate N rates, e.g. the performance of Yorkshire fog and red fescue, warrant a reconsideration of their poor reputation, particularly within the context of increasing grassland extensification. Breeding to improve selected characteristics, such as digestibility in red fescue, seems justified. Assessment of the grazing and ensiling qualities of secondary grasses require further study.
The influence of nitrogen fertilizer and Acremonium coenophialum on the soluble carbohydrate content of grazed and non‐grased Festuca arundinacea
Authors: BELESKY D. P. , WILKINSON S. R. , STUEDEMANN J. A.
Published: April 2006

A field study was conducted from 1983 through 1986 to ascertain the effect of endophyte (Acremonium coenophialum), nitrogen fertility and tall fescue (Festuca arundiancea) genotype upon the soluble carbohydrate content of tall fescue from grazed paddocks. Non‐grazed paddock exclosures were evaluated for 1984 and 1985. Plant tissues were extracted with 0·1 mol 1−1 H2SO4 to obtain acid‐extractable carbohydrate (AEC). The AEC concentration and yield (concentration × dry matter) varied among and within years, generally was not influenced by endophyte, and was influenced by N fertility and cultivar. The AEC concentration from non‐grazed exclosures was inversely related to AEC yield. Grazed paddock AEC concentration and yield were not significantly correlated. Grazed paddock AEC concentration remained fairly constant over the growing season, whereas AEC yield was greatest during periods of ample rainfall. The cultivar Johnstone generally had the greatest AEC concentration when compared with AU Triumph and KY‐31. Even though endophyte is a carbohydrate sink, sward scale effects on AEC, as influenced by endophyte, were virtually undetected, suggesting that presence of endophyte is not detrimental to the fescue host. Grazed and non‐grazed tall fescue AEC concentration and yield patterns differ and indicate the need to interpret non‐grazed quality and management data carefully.
Effect of fertilizer nitrogen rate and timing on herbage production and nitrogen use efficiency for first‐cut silage
Authors: LONG F. N. J. , KENNEDY S. J. , GRACEY H. I.
Published: April 2006

Eight field‐plot experiments were carried out on established grassland swards between 1984 and 1988 to examine the effects of date and rate of application of calcium ammonium nitrate (CAN) on herbage dry matter (DM) yield and apparent efficiency of nitrogen (N) use at first‐cut silage.

CAN application significantly increased (P <0 ·001) the mean yields of herbage and N uptakes by herbage in all experiments. Herbage yields were similar (P > 0·05) with N rates of 100 kg ha−1, 125 kg ha−1 or 150 kg ha−1 in five experiments but in the other three there were increases above 100 kg ha−1. Date of N application had a significant effect on DM yield in three experiments; this effect was inconsistent for both single and split dressings. Lower production was associated with reduced uptake of N, a trend that primarily reflected lower DM yields and not wide herbage N content variation.

It is concluded that selection of the date on which to apply fertilizer N in early spring to obtain optimum herbage yields at first‐cut silage often required little precision. The use of fertilizer N rates >100 kg ha−1 should be questioned where there are likely to be appreciable quantities of available N derived from non‐fertilizer sources.
The efficacy of a high magnesium grass cultivar in controlling hypomagnesaemia in grazing animals
Authors: MOSELEY G. , BAKER D. H.
Published: April 2006

A cultivar of Italian ryegrass (Bb 2067), specifically bred for high magnesium content, was assessed for its efficacy in alleviating the incidence of hypomagnesaemia in lactating ewes. Pasture and animal management was regulated to maximize the potential for the development of hypomagnesaemia. The incidence of clinical hypomagnesaemia in ewes grazing the control pasture (cv. RvP) was 21% within the first 10 days and this was accompanied by a significant fall of 35% in serum magnesium concentration. The incidence in ewes grazing the high magnesium cultivar was only 2·5% and there was no significant change in the serum magnesium concentration.

The mean magnesium content of Bb 2067 herbage (1·45 gkg DM‐1) was 48% higher than cv. RvP (0·93 g kg DM‐1) while calcium and phosphorus were 15% and 30% higher. The mean dry matter intake of ewes grazing Bb 2067 was higher than that of ewes grazing RvP, and although the difference was not statistically significant there were significantly increased intakes of magnesium, calcium and phosphorus for ewes grazing Bb 2067 compared with RvP. Ewes grazing Bb 2067 ingested more than the recommended allowance of magnesium and were close to sufficiency for calcium and phosphorus, while those grazing RvP were in serious deficit for all three minerals.

There was no significant difference in the ewe body weight loss between the treatments but lamb liveweight gain was significantly greater on the Bb 2067 pastures compared with those on cv. RvP.

It was concluded that the high magnesium grass provided an effective means of controlling hypomagnesaemia under grazing despite the extreme predisposing conditions imposed in this trial.
Detection of lolines in endophyte‐containing meadow fescue in The Netherlands and the effect of elevated temperature on induction of lolines in endophyte‐infected perennial ryegrass
Authors: HUIZING H. J. , VAN DER MOLEN W. , KLOEK W. , DEN NIJS A. P. M.
Published: April 2006

Plants from a Festuca pratensis variety which had caused‘eczema solare’among lambs in The Netherlands revealed the presence of endophytic Acremonium after microscopic evaluation. Combined gas chromatographic‐mass spectrometric analysis of extracts from seeds of these plants showed the occurrence of N‐formyl‐ as well as N‐acetyl‐loline which are formed as a result of the plant‐fungus association.

Endophyte‐infected Lolium perenne plants produced lolines only at elevated temperatures while non‐infected plants failed to synthesize these alkaloids under identical environmental conditions. Results indicate that presence of endophytic fungi together with growth at temperatures above 23°C is a prerequisite for induction of alkaloids detected in perennial ryegrass
Protein supplementation of formic acid‐ and enzyme‐treated silages. 1. Digestibilities, organic matter and fibre digestion
Authors: JACOBS J. L. , McALLAN A. B.
Published: April 2006

Two silages were made from perennial ryegrass ensiled without wilting in 2‐t capacity silos with the application of either formic acid or an enzyme mixture of cellulases and hemicellulases. Effluent losses were monitored over the ensiling period. Subsequent silage analysis showed that the enzyme‐treated silage had higher concentrations of residual water soluble carbohydrate, lactic acid and acetic acid, and lower concentrations of cellulose, ADF and NDF. Effluent production was higher with the enzyme silage (formic acid, 211 1 t−1; enzyme, 2671 t−1). The silages were either offered as the sole diet or supplemented with rapeseed meal at two levels (60 or 120 g fresh weight kg−1 silage DM offered) to growing steers equipped with rumen cannulae and T‐piece duodenal cannulae. Apparent whole tract digestibilities for DM, OM, N, ADF and NDF were similar for all diets although nitrogen retention (g d−1) was increased with supplementation of both silages (formic acid, 21·1; formic acid + 60 g, 23·5; formic acid+ 120 g, 28·5; enzyme, 22·6; enzyme + 60 g, 25·8; enzyme+ 120 g, 31·6). Rumen pH, ammonia and total volatile fatty acids patterns were similar. Supplementation increased the amount of organic matter apparently digested in the rumen (ADOMR) with formic acid‐treated silage but not with enzyme‐treated silage. Liveweight gains were similar for both unsupplemented silages (0·49 kg d−1). These increased to 0·55 and 0·65 kg d−1 for formic + 60 and formic + 120 respectively. Liveweight gains for the corresponding enzyme‐treated supplemented diets were 0·81 and 0·91 kg d−1 respectively. Liveweight gains on supplemented enzyme‐treated diets were significantly (P < 0·05) greater than those on formic acid‐treated diets.
The effect of cutting on the proportions of perennial ryegrass and white clover in mixtures
Authors: WOLEDGE JANE , REYNERI A. , TEWSON VERONICA , PARSONS A. J.
Published: April 2006

In two experiments with ryegrass/white clover mixtures, the proportion of clover was measured before and after cuts which removed 8‐75% of above‐ground biomass. Cutting was found to reduce the proportion of clover leaf area in the crop in both experiments, sometimes by as much as two‐thirds, and the proportion of clover dry weight, by up to half, in one of them. That is, the harvested material contained a greater proportion of clover than did the sward before the cut. This disproportionate removal of clover was due to clover having a greater proportion of its leaf near the top of the canopy than grass. It showed that preferential removal of clover occurs as a result of the purely passive selection by a mower, not only as a result of grazing by animals which may be capable of active as well as passive selection.

Despite the disadvantage to clover of losing more of its leaf area than grass, and in some cases more of its dry weight also, when the mixture was cut, the clover content of the sward did not decrease during the growing season as a whole. This was because, where no nitrogen fertilizer was applied, clover had a greater relative growth rate (RGR) than its companion grass during the growth periods between cuts and this increased its percentage of the mixture. Even where nitrogen was applied, clover equalled the RGR of grass and maintained its proportion of the crop, except in one instance.
Some effects of herbage composition, as influenced by previous grazing management, on milk production by cows grazing on ryegrass/white clover pastures. 1. Milk production in early spring: effects of different regrowth intervals during the preceding winter period
Authors: HOLMES C. W. , HOOGENDOORN C. J. , RYAN M. P. , CHU A. C. P.
Published: April 2006

Two experiments (1a and 1b) were carried out to examine the effects of differences in pre‐grazing herbage mass and composition on milk production by cows grazing in early spring. Swards with high (5 · 1t DM ha−1) or low (2 · 9 t DM ha‐1) pre‐grazing masses in early spring were created by either long or short periods of regrowth during the preceding winter.

The low‐mass swards contained lower concentrations of grass stem and senescent material, but higher concentrations of clover, than the high‐mass swards. Herbage from the low‐mass swards was also more digestible.

Cows were offered common daily herbage allowances from both swards (26 and 22 kg DM cow−1 in Experiments la and lb respectively). The cows grazing on the low‐mass swards produced significantly greater yields of milk, milk fat and milk protein.

The results show that herbage from the lowmass swards was of higher feeding value for lactating cows in early lactation. The practical implications for milk production per cow and per hectare are discussed.