bluuebunny/crossref_metadata_2025 huggingface dataset:
Silage and milk production: comparisons between hays of different digestibilities as silage supplements
Authors: RETTER W. C. , CASTLE M. E.
Published: April 2006

In three separate feeding experiments using a total of thirty individually‐housed Ayrshire cows three silages made from perennial ryegrass were given ad libitum together with supplements of four different hays in the long form. The in vitro D‐values of the silages ranged from 0·298 to 0·283, and the hays from 0·280 to 0·200. The daily intake of hay DM varied from 0·2 to 4·2 kg per cow and was given either without or with a daily maximum of 2·2 kg concentrate DM containing 379–527 g CP per kg DM. On average, 1 kg hay DM decreased silage intake by 0·24 kg DM with a range of 0·21–1·20 kg. The hay supplements had only small and non‐significant effects on total DM intake, milk yield and milk composition, but increased the daily intake of drinking water. In three behavioural studies, the eating and ruminating times expressed as min per kg DM did not differ significantly between the various supplement treatments. It is concluded that hay has only a marginal value as a supplement for grass silage, although the hay could serve as a useful ‘buffer’ feed if the amount of silage was limited.
The pattern of growth in swards of two contrasting varieties of white clover in winter and spring
Authors: DAVIES ALISON , EVANS M. ELEANOR
Published: April 2006

In a study of growth rates and developmental morphology of simulated swards of two contrasting white clover varieties, Katrina and Kent, it was found that both varieties continued to produce dry matter throughout the winter at Aberystwyth. The gross crop growth rate in the coldest periods was about 7 kg ha‐1 d‐1. The rates of formation and loss of new leaves were approximately equal so that there was no net increase in weight until the latter part of March. This initial net weight increase in both varieties was observed in the same harvest interval, the most important factor being the difference in weight between the new leaf plus petiole unit and the weight of the unit which it replaced. The weight of laminae and petioles throughout the experiment was somewhat higher in Katrina which has come to be regarded as the ‘earlier’ variety.

The prospects for improving spring production in white clover by variety improvement are discussed.
The preharvest use of glyphosate in the ryegrass seed crop
Authors: HAMPTON J. G. , HEBBLETHWAITE P. D.
Published: April 2006

Preharvest application of 1 and 2 litres ha‐1 IPA glyphosate (glyphosate) to a seed crop of S24 perennial ryegrass with moisture concentrations of around 400 and 340 g kg‐1 (40 and 34% moisture content w/w) failed to significantly lower seed and straw moisture concentration at harvest and consequently did not affect combine rate. Addition of extra surfactants and ammonium sulphate to glyphosate did not significantly increase the rate of desiccation.

The quality of harvested seed was impaired at both rates and application times. Germination was significantly lowered through the production of abnormal seedlings. The germination of seed harvested in the previous year from glyphosatetreated plots decreased with storage. Seed vigour, germination rate and field emergence were also significantly decreased as a result of glyphosate application. The effect of glyphosate on seed quality precludes its preharvest use as a desiccant in the ryegrass seed crop.

Harvesting difficulties due to the production of secondary vegetative tillers may be overcome by swathing rather than direct combining.
A technique for estimating rate of disappearance of dead herbage in pasture
Authors: YATES J. J.
Published: April 2006

A technique for estimating the rate of disappearance of material from samples of dead herbage protected by simple nylon or wire mesh covers is described. Using this technique on a perennial ryegrass sward in southern England during August‐November, relative rates of disappearance close to 0·204 g g‐1 d‐1 (DM) were obtained, but the variability was high. When herbage killed with paraquat was used, the rate of disappearance was higher and the variability lower. There were only small differences in the temperatures recorded in a normal sward and within samples of dead herbage under mesh covers.
Root size estimates of red clover and alfalfa based on electrical capacitance and root diameter measurements
Authors: KENDALL W. A. , PEDERSON G. A. , HILL R. R.
Published: April 2006

Electrical capacitance and root diameter techniques for estimating root dry weight were evaluated in one test with red clover plants grown on slant‐boards in plant growth chambers for 37–77 d, and in six tests with alfalfa grown in the field for 55–165 d. Root dry weights of red clover were estimated satisfactorily with regression equations from both diameter (R2=90%) and capacitance (R2=76%) measurements. Root dry weights of alfalfa were estimated satisfactorily throughout the entire season from diameter values (R2 from 51 to 92%). Alfalfa root weight was significantly (P <0·25) related to capacitance values at the beginning and at the end of the season but not at mid‐season. Electrical capacitance measurements were similar for intact root systems and roots severed 4 cm below the crown in separate experiments with red clover and with alfalfa. The root diameter technique provided an accurate, rapid and inexpensive method of estimating root size throughout the first season of growth. The root capacitance method provided satisfactory estimates of roots at certain times during the summer. Neither method would be useful if a large portion of the root was naturally severed.
A statistical assessment of the dry‐weight‐rank method of pasture sampling
Authors: SANDLAND R. L. , ALEXANDER J. C. , HAYDOCK K. P.
Published: April 2006

The statistical properties and applicability of the Dry‐Weight‐Rank (DWR) method of pasture sampling are examined. Formulae for the expected value and variance of the DWR estimates are presented.

The extent of bias in DWR is examined using several mathematical models. DWR is shown to break down when estimating multinomial proportions; however it provides good estimates for a subset of models simulated from a class of compound probability distributions.

The success of DWR in practice does not rest on a theoretical basis. It appears to be a remarkable empirical discovery that DWR estimates are virtually unbiased on most pasture types. Several cases are considered where difficulties may be encountered in using DWR. Provided the theoretical reservations of this paper are borne in mind, DWR will continue to be a useful practical tool, especially in the absence of non‐destructive observational alternatives.
Grass height as an indicator for supplementary feeding of continuously stocked dairy cows
Authors: LEAVER J. D.
Published: April 2006

Three groups of cows were continuously stocked on pasture and offered supplementary concentrates according to the herbage height measured weekly with a grass disc. Concentrates were offered when the mean herbage height fell below 9 cm for treatment A, 7 cm for treatment B and 5 cm for treatment C at a rate of 1 kg d‐1 for each 0·2‐cm decline below these threshold levels. If the herbage height declined by more than 1·2 cm (8 kg concentrates d‐1) hay was offered in addition ad libitum. The stocking rates for all three treatments were 5·2, 3·2 and 3·2 cows ha‐1 for three successive 8‐week periods. For treatments A, B and C the mean concentrate DM intakes were 3·2, 1·2 and 1·2 kg d‐1 (treatment A also received 0·2 kg hay DM d‐1), and the mean daily milk yields were 17·2, 16·2 and 15·2 kg respectively. The increasing level of supplementary feeding from treatment C to A also resulted in an increase in liveweight and body condition score change, and a reduction in milk fat.
Effects of season and level of grazing on the utilization of heather by sheep. 3. Longer‐term responses and sward recovery
Authors: GRANT SHEILA A. , MILNE J. A. , BARTHRAM G. T. , SOUTER W. G.
Published: April 2006

The effects of sheep grazing on the development of and production from heather swards and on intake and diet selection by grazing Scottish Blackface wether sheep were studied in an experiment in which sheep numbers were adjusted to remove 0, 40% or 80% by weight of current season's shoots in summer and in autumn for a period of 5 years. All combinations of season and level of grazing were provided. The plots were divided after 2 years and grazing was continued for a further 3 years on one subplot but discontinued on the other.

Sward productivity during the 5 years of grazing was unaffected at the 40% level of shoot removal but at the 80% level was reduced by up to 66%.

After a season's uninterrupted growth at the end of the experiment heather cover and herbage mass were lower and current season's shoots as a proportion of total mass were higher on those treatments which received the greatest severity of grazing. Weight of current season's shoots was unaffected on treatments which had received the 40% level of shoot removal but was reduced by 40% and 50% on treatments which had received the 80% level in summer and autumn respectively. On the rested subplots sward recovery was such that no treatment effects remained after 3 years except with respect to 80% shoot removal in autumn where herbage mass was reduced compared with other treatments.

Intakes of digestible organic matter per sheep were higher at the 80% than the 40% level of grazing in the fifth year of the experiment. This was ascribed to the ingestion of new shoot growth from the twig bases on the 80% level of removal treatments. Intake and digestibility were higher in the summer on those treatments which had received the 80% level of removal in previous autumns. Over the 5 years of the experiment there was a small decline in intake and digestibility values, with the decline being greatest in the summer and at low levels of grazing.

Floristic changes differed on the rested and grazed areas. On the rested subplots in the fourth year after grazing stopped, heather height was lower and cover by grasses, sedges and herbs was greater on treatments which previously had received the highest levels of utilization. On bare areas the rate of recovery of heather was rapid where shoots as well as seedlings contributed to recovery growth. On the grazed subplots, with the exception of the low‐growing ruderal Rumex acetosella, cover due to grasses, sedges and herbs remained low as species other than heather were selectively grazed.

Relationships among stocking rates, grazing behaviour and heather utilization are discussed and guidelines for the recognition of overgrazing are outlined.
Sodium, potassium and calcium concentrations in varieties of Dactylis glomerata
Authors: MÍKA V.
Published: April 2006

Twelve varieties of cocksfoot, Dactylis glomerata L., were analysed for three mineral elements (Na, K, Ca) and their dry matter (DM) yields were measured in pot and field trials. Among these characteristics there were strong varietal differences in Na concentration, whereas in other cases the varietal differences were less significant. The concentrations of individual mineral elements were, in most cases, independent of yield and of one another.

Parent plants and their clonal derivatives were highly correlated in Na and Ca concentration as well as in DM yield. Tiller size or position on the parental plant had no significant effects on the mineral concentrations or DM yields of clones derived from separated tillers.

Within varieties continuous variation was observed for Na concentration and the range of variation increased with increasing mean Na concentration. When plants were grown under different experimental conditions there was a high repeatability in Na concentration within varieties over cuts and years. This result was taken as an indication of a strong genetic basis for Na concentration. The results obtained in this study show that it is possible to develop grass varieties of defined potential Na concentration.
Silage and milk production: a comparison between three rates of high‐protein concentrate supplementation of grass silages of two digestibilities
Authors: CASTLE M. E. , GILL M. S. , WATSON J. N.
Published: April 2006

Grass silages made from first‐harvest perennial ryegrass in mid‐May and early‐June and termed high‐D and low‐D respectively had mean DOMD values of 694 and 633 g kg−1 and were offered ad libitum to twelve Ayrshire cows in a 16‐week feeding experiment using a cyclic changeover design. The silages were supplemented with a concentrate containing 363g CP per kg DM at daily rates of 1.5, 3.0 and 4.5 kg per cow. The average daily intakes of silage DM were 12.6 and 11.1 kg per cow on the high‐ and low‐D silage treatments respectively, and were not significantly different on the three concentrate treatments. The mean daily milk yields were 171, 18.6 and 21.0 kg per cow on the low‐D silage treatments, and 19.6, 21.2 and 22.8 kg per cow on the high‐D silage treatments at the 1.5, 3.0 and 4.5 kg rates of concentrate feeding respectively. Fat and lactose concentrations in the milk were not affected significantly by treatment, whereas the CP and SNF concentrations increased progressively and significantly as the rate of supplementary feeding increased. It is concluded that a high‐protein concentrate supplement allows silage to make the maximum contribution in the diet, and gives a high response in terms of milk yield and composition.
Concentrate supplementation of grazing dairy cows
Authors: MEIJS J. A. C. , HOEKSTRA J. A.
Published: April 2006

Two experiments are described in which twenty‐four spring‐calving Dutch Friesian cows were allocated between six grazing treatments (two levels of daily herbage allowance × three levels of daily concentrate intake) in a 2 × 3 factorial design. The swards consisted predominantly of perennial ryegrass. A two‐machine sward‐cutting technique (with correction for herbage accumulation during grazing) was used for estimating herbage intake by cows which grazed swards for 3 or 4d. Experiment 1 was carried out for 16 weeks of the grazing season of 1981 and experiment 2 for 18 weeks in 1982.

Daily herbage OM allowances in both experiments were 16 and 24 kg per cow above 4 cm cutting height. Daily concentrate OM intake ranged from 0.8 to 5.6 kg per cow. The effect of concentrates on herbage intake differed significantly between allowances. At the low allowance level and at daily concentrate OM intakes of 0.8, 3.2 and 5.6 kg per cow daily herbage OM intake was 10.9, 10.6 and 10.4 kg per cow respectively and the mean substitution rate of herbage by concentrates was only 0.1. At the high allowance level and at daily concentrate OM intakes of 0.8, 3.2 and 5.6 kg per cow daily herbage OM intake was 14.8, 13.6 and 12.4 kg per cow respectively and mean substitution rate was 0.5 kg herbage OM (kg concentrate OM)−1.
Dry matter and quality of herbage harvested from Holcus lanatus and Lolium perenne grown in monocultures and in mixtures
Authors: HARVEY B. M. R. , CROTHERS S. H. , HAYES P.
Published: April 2006

The herbage dry matter (DM) harvested, N response and herbage quality of monocultures and mixtures of Holcus lanatus (local ecotype) and Lolium perenne (cv. S24) were compared in a field experiment. The species were seeded in the proportions 100:0, 75:25, 50:50, 25:75 and 0: 100; three rates of N were applied (150, 300 and 450 kg ha−1) and five or six cuts were taken in each of four harvest years.

H. lanatus established poorly in the seeding year and in the first full harvest year L. perenne contributed 1, 54, 76, 89 and 99% of the total herbage DM harvested from the five sward types (mean of N treatments). Only a small decline in the L. perenne content of the swards occurred during the experiment.

Total amounts of herbage harvested were significantly lower for H. lanatus monoculture than for the other sward types in three of the four harvest years However, L perenne monoculture yielded significantly more total DM than mixtures with H lanatus in only one of the four harvest years. The five sward types did not differ overall in response to N fertilization. Nitrogen, phosphate and potassium content of the herbage was greatest for H. lanatus monoculture and decreased with increasing proportions ofL perenne present in the mixtures.

Thus the presence of a high proportion of H. lanatus in mixture with L. perenne cv. S24 had
The mineral metabolism of sheep fed high‐ and low‐magnesium selections of Italian ryegrass
Authors: MOSELEY G. , GRIFFITHS D. W.
Published: April 2006

Two experimental populations of Italian ryegrass selected for high and low magnesium content were established as swards, harvested fresh daily and offered to sheep. Chemical analysis of the crops showed a 44% higher Mg and a 22% higher Ca concentration in the high‐Mg selection but no significant differences between the selections for the other minerals.

Blood and rumen contents were sampled throughout the feeding period and voluntary intake, digestibility and mineral balances for Na, K, Mg, Ca and P were determined. Magnesium intake, apparent availability and retention were significantly greater with the high‐Mg selection. There were no significant differences in the plasma‐mineral concentrations and all were within the normal range. Rumen fluid from animals fed the high‐Mg selection had a higher proportion of soluble Mg and a higher Na:K ratio in the supernatant liquor.
Orchardgrass and perennial ryegrass with applied nitrogen and in mixtures with legumes
Authors: SOLLENBERGER L. E. , TEMPLETON W. C. , HILL R. R.
Published: April 2006

High‐yielding grass‐legume mixtures play an important role in forage‐animal systems but finding compatible and adapted species can sometimes be difficult. The objective of this study was to examine productivity of perennial ryegrass and orchardgrass in pure stands with N and in mixtures with legumes.

Broadcast sowings were made on conventionally prepared seedbeds in August 1979 and May 1980 on a Hagerstown silt loam soil (fine, mixed mesic Typic Hapludalf). When sown alone orchardgrass cv. Pennlate and perennial ryegrass cv. Reveille received rates of N ranging from 0 to 448 kg ha−1 a−1. The grasses were also grown in mixtures with alfalfa cv. Arc, red clover cv. Arlington, or birds foot trefoil cv. Viking. The same legumes were sown alone. Four legume seed rates were used in both the pure legume and mixed stands.

Orchardgrass‐N swards were more productive than ryegrass‐N swards over 3 years. More dry matter (DM) was harvested from pure stands of
An evaluation of the use of short‐term weight changes in grazing sheep for estimating herbage intake
Authors: PENNING P. D. , HOOPER G. E.
Published: April 2006

A technique for estimating herbage intake by weighing sheep before and after grazing, with an allowance for insensible weight loss (IWL) was evaluated.

Live weights were estimated by weighing each animal 200 times using an electronic balance and a microcomputer. This enabled each sheep to be weighed to ± 10 g and overcame the problem of fluctuation in weight due to movement. Mean rates of IWL in housed sheep were 2·3, 1·4, and 0·8 g min−1 for walking, standing eating or idling and when lying ruminating respectively. Intake rate (IR) estimated by weighing gave a small but significant bias of −0·8 g min−1 when compared with measurements of IR made using housed sheep. Estimates of IWL and IR were made with ewes grazing continuously stocked ryegrass swards maintained at surface heights of 3,6,9 and 12 cm. IWL was higher outdoors than indoors and tended to be higher on the longer swards. IR estimated by weighing gave similar results to those obtained using the chromic oxide technique. At a sward surface height of 3 cm, IR and total intake were lower than for taller swards and total time spent grazing decreased with increasing sward surface height.
Effect of nutrient application and herbicides on root competition between green panic seedlings and a Heteropogon grassland sward
Authors: COOK S. J.
Published: April 2006

Root competition was studied between seedlings of green panic (Panicum maximum var. trichoglume) and Heteropogon contortus in a native grassland sward clipped regularly to a height of 5·7 cm, and to which supplementary irrigation was applied. The influence of fertilizer addition and root competition from the grassland sward on seedling growth during the 42 days following emergence was determined. Root competition was excluded by steel tubes, or eliminated by killing the native sward with herbicides.

Seedling growth was poor where neither root competition was controlled nor fertilizer was applied; at 42 days the seedlings were still less than 6 cm high with three leaves and one tiller. When root competition was controlled, either by steel tubes or herbicide, seedling growth increased significantly. Growth was greatest in the herbicide‐treated plots where fertilizer was applied, seedlings at day 42 being 48 cm high with sixty‐three leaves and nineteen tillers.

Competition for nutrients appeared to be the primary factor limiting seedling growth and this was largely overcome by fertilizer application. Competition for nutrients appeared to increase the fertilizer requirements of pastures oversown into live swards compared with that of pastures oversown into herbicide‐treated swards.
The reaction of grazing sheep and cattle to the presence of dung from the same or the other species
Authors: FORBES T. D. A. , HODGSON J.
Published: April 2006

An experiment is described in which steers and wether sheep separately grazed perennial ryegrass swards, managed so that half of each sward had previously been grazed by sheep and half by cattle. The influence of the presence of dung from the same or the other species on grazing patterns and herbage utilization was examined.

Regression analysis of extended sward height along transects laid across dung pats after grazing revealed that the limits of the rejected herbage were more clearly defined around cattle dung than sheep dung when grazed by cattle, whereas there was less distinct avoidance of herbage around both cattle and sheep dung when grazed by sheep. As grazing proceeded there was a progressive movement of animals from the half of the plot previously grazed by the same species to the half previously grazed by the opposite species, and this movement was more marked in the cattle than in the sheep.

It was concluded that under mixed grazing a greater proportion of the herbage would be available to the sheep giving them an advantage over the cattle.
Supplementary feeding of forage to grazing dairy cows
Authors: PHILLIPS C J. C , LEAVER J. D.
Published: April 2006

For three 8‐week periods of the grazing season 48 spring‐calving cows were continuously stocked at either a high or a low rate (average 4.9 and 4.3 cows ha−1 respectively) which declined through the season. Within each stocking rate group half the cows were allowed access to hay for 45 min after morning milking; the other half received no hay.

Total dry matter (DM) intakes were increased by offering hay, and intakes of hay were greater at the high stocking rate and during prolonged periods of inclement weather. However, there were times when, because of low herbage height and adverse weather, offering hay once daily could not prevent a decline in total DM intake. Grazing time was reduced and ruminating time increased by offering hay, but the rate of biting at pasture was unaffected. Hay DM was eaten at twice the rate of intake of herbage DM.

Offering hay increased milk yield in early season and liveweight gain in late season. The benefits of offering hay were greatest for the higher yielding cows. There were no significant effects on milk composition.

Stocking rate had only small effects on herbage height, but stocking at the higher rate tended to reduce herbage DM intake and reduced live‐weight gain in late season. Levels of utilized metabolizable energy from grazed herbage were high (average 106 GJ ha−1) but were reduced by feeding hay and stocking at the lower rate.
The effect of frequency of harvesting grass for silage on the intake and performance of beef cattle
Authors: STEEN R. W. J. , McILMOYLE W. A.
Published: April 2006

Two randomized‐block experiments were conducted to examine the effects of frequency of harvesting grass for silage on the intake and performance of beef cattle. In both experiments swards of S24 perennial ryegrass were harvested at 63‐, 49‐ and 38‐d intervals throughout the growing season. Grass harvested before and after 10 July was ensiled separately and termed spring and autumn silage respectively. In Experiment 1 the silages were offered ad libitum either unsupplemented or supplemented with 2 kg barley per head daily to eighty‐four Hereford‐cross weaned, single‐suckled steer calves of mean initial live weight 284 kg, in a 3 × 2 × 2 factorial design. Silage dry matter (DM) intakes and liveweight gains for the silages harvested at 63‐, 49‐ and 38‐d intervals were 4.80, 0.72; 4.49,0.76; and 4.62,0.78 kg d−1 for the spring silages and 4.69, 0.67; 4.59, 0.85; and 4.55,0.86 kg d−1 for the autumn silages respectively. There was no significant interaction between frequency of harvesting and concentrate supplementation. In Experiment 2 the silages were offered ad libitum and unsupplemented to forty‐two Hereford‐cross weaned, single‐suckled steer calves of mean initial live weight 240 kg, and forty‐two Hereford‐cross store cattle of mean initial live weight 356 kg, in a 3 × 2 × 2 factorial design. Silage DM intakes and liveweight gains for the silages harvested at 63‐, 49‐ and 38‐d intervals were 4.94,0.49; 5.69,0.80; and 619,0.93 kg d−1 for the spring silages and 5.50, 0.61; 5.57, 0.72; and 505, 0.65 kg d−1 for the autumn silages respectively. There were no significant interactions between frequency of harvesting and type of animal. It is concluded that a cutting interval of 49 d commencing on 21 May is likely to be optimum for this type of sward except under exceptional weather conditions.
A comparison of seed harvesting methods for perennial ryegrass treated with the growth retardant paclobutrazol
Authors: HAMPTON J. G. , HEBBLETHWAITE P. D.
Published: April 2006

Methods of harvesting seed of perennial ryegrass cv. S24 treated with the growth retardant paclobutrazol applied at spikelet initiation at a rate of 2.0 kg active ingredient ha−1 were examined in 1982. The greatest seed yield (2202 kg ha−1) was obtained from swathing the crop at 35% seed moisture content and combining 2 days later, but this was not significantly different from that obtained from swathing at 48% seed moisture content or double direct combining at 35% seed moisture content. Seed yields from a single direct combining at either 35% or 25% seed moisture content were significantly lower than those of other treatments.
The combined use of fertilizer nitrogen and white clover on grazed ryegrass swards
Authors: REID D.
Published: April 2006

A 1‐year grazing experiment with dairy cows is described in which the milk yield and herbage intake from a sward of S23 perennial ryegrass alone receiving fertilizer N at an annual rate of 360 kg ha−1 were compared with those from a ryegrass‐white clover var. Blanca sward given a total N application of 180 kg ha−1. Both treatments gave virtually the same total milk yield of about 12500 kg ha−1 over a 20‐week grazing season.
Use of a model to analyse the effects of continuous grazing managements on seasonal patterns of grass production
Authors: JOHNSON I. R. , PARSONS A. J.
Published: April 2006

The effects of management on the seasonal patterns of production of grass swards under continuous grazing are examined using a previously described mathematical model. For continuous set‐stocking it is observed that, if the leaf area index of the sward at turn‐out is too low, there may be a sustained reduction in animal intake throughout the season. Under continuous variable stocking, where the sward is maintained at a constant leaf area index, animal intake is observed to follow broadly a pattern determined by the environmental conditions. It is concluded that grass production, in terms of both gross tissue production and animal intake, is not independent of management. Furthermore, no evidence is found to suggest that the seasonal patterns of production undercutting and grazing are the same.
Effect of seed rate of red clover and of companion timothy or tall fescue on herbage production
Authors: FRAME J. , HARKESS R. D. , HUNT I. V.
Published: April 2006

Tetraploid red clover (cv. Hungaropoly) was sown at seed rates of 6,12 or 18 kg ha−1 alone and in mixture with timothy (cv. Scots) at 2, 4 or 6 kg ha−1 or with tall fescue (cv. S170) at 6,12 or 18 kg ha−1. Two ‘silage’ crops and an ‘aftermath grazing’ crop were harvested in 2 successive years. In harvest years 1 and 2, total herbage production levels of 11.12 and 7.47 t dry matter (DM) ha−1 respectively were obtained from pure‐sown red clover compared with 11.84 and 8.78 t DM ha−1 for red clover‐timothy and 12.23 and 9.64 t DM ha−1 for red clover‐tall fescue. Corresponding red clover production levels were 10.93 and 5.30 t DM ha−1 (red clover swards), 8.04 and 3.131 ha−1 (red clover‐timothy), and 6.42 and 109 t ha−1 (red clover‐tall fescue).

Total herbage organic matter digestibility was improved by the timothy companion grass but not consistently by the tall fescue, whereas crude protein (CP) concentration was decreased by the addition of either grass. Increased seed rate intensified these effects, as well as the general effect of the companion grass in depressing red clover DM, digestible organic matter (DOM) and CP production.

Total herbage DM, DOM and CP were not markedly affected by increasing red clover seed rate but red clover DM, DOM and CP were increased as red clover seed rate was raised, due to increases in the red clover component.

The potential for silage cropping of red clover swards was confirmed but there was advantage in sowing a companion grass. Taking yield and quality parameters into consideration, timothy proved a better companion than tall fescue. A seed rate of 2 or 4 kg ha−1 timothy and 12 kg ha−1 red clover proved the most satisfactory.
The effects of silage harvesting system and supplementation of silage‐based diets by protein and methionine hydroxy analogue on the performance of lactating cows
Authors: GORDON F. J. , UNSWORTH E. F.
Published: April 2006

Three silages were produced by harvesting grass using either a flail (F), double‐chop (DC) or a precision‐chop (PC) forage harvester. Each silage was ensiled unwilted and with formic acid additive applied at the mean rate of 2·2 1 t‐1 of grass. All three silages were well preserved and had mean particle lengths of 54, 49 and 26 mm and digestible organic ma er in dry ma er (DOMD) values of 0·67,0·66 and 0·66 for the F, DC and PC silages, respectively.

The three silages were offered ad libitum to three groups each of 21 British Friesian cows, with a mean calving date of 29 January, from day 8 of lactation until 9 April. Within each silage group all cows were offered 4·1 kg dry ma er (DM) d‐1 of a control supplement divided equally in two feeds and given during milking. In addition, 24 kg DM d‐1 of the control supplement (C), a high protein supplement (HP) or a supplement containing methionine hydroxy analogue (MHA) were given at midday. The mean crude protein contents of the total supplementary feeds given were 193 253.and 195gkg for the C, HP and MHA treatments, respectively.

The treatment effects showed no significant interactions between silage harvesting system and type of supplement. Silage harvesting system influenced milk yield, with the mean yields over the final 21 days of the experiment being 26·1, 27·4 and 25·5 kg d‐1 for the F, DC and PC silages, respectively, and the difference between DC and PC achieved significance (P <0·05). However, the milk from cows given DC had a significantly lower concentration of fat (P <0·01) and silage harvesting system had no effect on the yield of fat or protein. The type of supplement had no significant effect on milk yield, with the mean yields over the final 21 days of the experiment being 264, 267 and 259 kg d‐1 for the C, HP and MHA supplements, respectively.
An evaluation of effluent from grass silage as a feed for beef cattle offered silage‐based diets
Authors: STEEN R. W. J.
Published: April 2006

Four experiments were carried out to evaluate effluent from grass silage as a feed for beef cattle. Castrated male cattle (steers) with mean initial live weights of 380,460 and 400 kg in Experiments 1–3 were offered effluent, in addition to a diet of grass silage given ad libitum and supplemented with cereal‐based concentrates. The cattle readily consumed effluent in preference to fresh water, the mean intake over the three experiments being 12·71 per head daily containing 0·77 kg dry matter (DM). Supplementation with effluent did not affect silage DM intake and increased total DM intake by 10%. Digestible energy concentrations of 13·1 and 16·6 MJ kg‐‐1 DM and organic matter, respectively, were determined for effluent in Experiment 4. There were no problems of ill health in any of the 69 cattle which were offered effluent. It is concluded that fresh or well‐preserved stored effluent from grass silage is readily consumed by beef cattle, is of high nutritive value and could enable savings to be made in total feed costs.
The effect of addition of sugar and inoculation with two commercial inoculants on the fermentation of lucerne silage in laboratory silos
Authors: SEALE D. R. , HENDERSON A. R , PETTERSSON K. O. , LOWE J. F.
Published: April 2006

Lucerne (DM 236 g kg‐1, WSC 49 g (kg DM)‐1) was ensiled in test‐tube silos with or without either glucose or fructose and with or without one of two commercial inoculants. The WSC content of the forage as ensiled was too low to obtain a well preserved untreated silage. By day 4 the pH values of the silages with added sugar or inoculant were significantly lower (P< 0·001) than the control silage. A satisfactory fermentation was attained only in the silages to which sugar and an inoculant had been added. These silages had a lower pH, more protein‐N (P< 0·001), less ammonia‐N (P<0·001), a faster increase in counts of lactic acid bacteria, and decrease in counts of coliforms than the other silages. Homo‐fermentative lactic acid bacteria dominated the fermentation in the inoculated silages while leuconostocs dominated the early stages of fermentation in the control silages. The results indicate that if there is insufficient sugar in the original crop, then the bacteria in an inoculant will not be able to produce enough lactic acid to lower the pH to an acceptable level. This has important implications for the ensilage of lucerne and other highly buffered low sugar crops.
The sulphur status of intensive grassland sites in southern Scotland
Authors: KEER J. I. , McLAREN R. G. , SWIFT R. S.
Published: April 2006

Field trials were carried out at five sites in southern Scotland to examine the sulphur status of intensively grown grass under varying Inputs of atmospheric and rainfall sulphur. Sulphur budgets were prepared by comparing amounts of sulphur removed at harvest with sulphur inputs from rainfall, the atmosphere and fertilizers.

No yield responses to added sulphur were obtained, although soil‐derived sulphur was essential for the maintenance of optimal sulphur levels in herbage. Where no fertilizer sulphur was added, mineralization of soil organic sulphur supplied approximately 8 to 18 kg S ha‐1 annually during the growing season. Maintenance requirements of 5 to 10 kg S ha‐1 annually were indicated at the Dumfriesshire and Midlothian sites and 20 kg S ha‐1 annually at the Berwickshire sites to prevent a decline in soil sulphur reserves. Total sulphur concentrations of less than 2 g S kg‐1 dry matter were observed in herbage at some samplings indicating marginal sulphur sufficiency. Sulphate levels in herbage, expressed as a percentage of total sulphur, also indicated that sulphur supplies barely matched crop requirements.
Botanical composition of permanent grassland in England and Wales in relation to soil, environment and management factors
Authors: HOPKINS A.
Published: April 2006

Grassland in England and Wales accounts for nearly 60% of the enclosed agricultural land and approximately 50% is at least 20 years old. Botanical composition, especially amongst older grassland, is extremely variable.

A survey of 502 grassland farms was conducted in the 1970s. Factors affecting botanical composition of individual fields have been investigated using correlation and regression analyses and swards of similar botanical composition grouped using cluster analysis. Lolium perenne, Agrostis spp. and Holcus lanatus were numerically the most important species, contributing, on average, 35%. 21% and 10%, respectively. Most older swards contained Lolium perenne and Agrostis spp. in varying proportions depending on drainage, soil fertility and management. Swards containing a significant proportion of Trifolium repens were associated with adequate drainage, good soil nutrient status, low inputs of fertilizer nitrogen and hard grazing. Of the other common species Holcus lanatus was associated with poor drainage, low soil fertility, hay cutting, short‐season grazing and low fertilizer N. Festuca rubra was mainly in older swards, at higher elevations and with low fertilizer N but heavy stocking. Swards containing Rumex spp., Poa trivialis and other sown grasses were associated with mowing together with reasonably high soil fertility.
Effect of harvesting system on nutrient losses during silage making. 2. In‐silo losses
Authors: MAYNE C. S. , GORDON F. J.
Published: April 2006

Nutrient losses during the in‐silo period were determined following the ensiling of grass using three differing harvesting systems. The treatments were either (a) harvesting herbage directly by means of a flail harvester (unwilted flail, UF) or (b) pre‐mowing of herbage with a rotary drum mower and lifting using a precision chop forage harvester with wilting (WP) and without wilting (UP). Herbage was harvested and ensiled over the period 26–29 May 1982, and a good fermentation was achieved with all three silages. Losses of dry matter (DM), organic matter (OM) and crude protein (CP) during the in‐silo period were greatest with the UF system, intermediate with the UP system and lowest with the WP system. Gross energy losses followed the same trend with losses (as a percentage of ensiled levels) of 18·6, 9·8 and 4·4% for the UF, UP and WP systems, respectively. Gross energy loss as effluent accounted for 24% and 22% of total gross energy ensiled for the UF and UP treatments. Patterns of effluent flow differed between the two unwilted silages with a higher peak flow rate with the UF material. Total effluent production at 354 ml (kg DM ensiled)‐1 was greater for the UF material than for the UP material (288 ml (kg DM ensiled)‐1). Nutrient loss through surface waste was similar for all three silages whereas gross energy losses arising through residual respiration, fermentation and gaseous loss amounted to 149%, 6·7% and 31% of that ensiled for the UF, UP and WP silages, respectively. The results of this study, taken in conjunction with those of an earlier study where field losses were assessed, indicate that recovery of gross energy during silage making was very similar for the UP and WP systems and only marginally greater than that recovered with the UF system.
The effect of dry matter content and silage additives on the fermentation of grass silage on commercial farms
Authors: HAIGH P. M.
Published: April 2006

A total of 1713 samples of silage from commercial farm silos were analysed to investigate the effect of dry matter (DM) content and chemical additives on fermentation as measured by ammonia‐N concentration and pH, Increasing DM content without additive use had a major beneficial influence upon fermentation. When silage DM contents were greater than 260 g kg‐1 83% of silages were well fermented, with average ammonia‐N concentrations of 94 g (kg total N)‐1 and pH 4.36. With diminishing DM concentration the proportion of well fermented silages declined. In the DM range 220‐260 g kg‐1 67% of silages were well fermented with ammonia‐N concentrations of 125 g (kg total N)‐1 and pH 4.30, in the DM range 180‐220 g kg‐1 48% were well fermented with ammonia‐N at 151 g (kg total N)‐1 and pH 4.38 and with DM below 180 g kg‐1 no silages were well fermented with ammonia‐N concentration of 252 g (kg total N)‐1 and pH 4.84.

The benefit of chemical additives, albeit at poorly defined and often inadequate rates, was small in comparison to that of increased DM concentration. Below DM concentrations of 180 and 220 g kg‐1, the only benefit was that formic acid decreased ammonia‐N to 151 g (kg total N)‐1 and pH to 4.32 compared with 163 g (kg total N)‐1 and pH 4.43 for untreated silages. Within the DM range 220‐260 g kg‐1 formic acid decreased ammonia‐N level to 104 g (kg total N)‐1 and pH to 4.07, and there was a slight benefit from using sulphuric acid/formalin which decreased ammonia‐N to 117 g (kg total N)‐1 and pH to 4.23 compared with 125 g (kg total N)‐1 and pH 4.27 for untreated silages. Above 260 g DM kg‐1 both formic acid and sulphuric acid/formalin provided a small but consistent decrease in ammonia‐N and pH compared with untreated silages. Chemical additive use conferred no other benefit when compared with untreated silage. Calcium formate/sodium nitrite mixtures and acid mixture use provided no benefit in fermentation compared with untreated herbage.
Preservation of plant material by large scale sorption freeze‐drying
Authors: COLEBROOK W. F. , MELLOR J. D.
Published: April 2006

A large‐scale sealed system for freeze‐drying herbage is described. It utilizes the principle of sorption drying and is dependent upon the vapour pressure differential (VPD) between the herbage and the silica gel drying agent. Ice sublimes to vapour from the sample in a system operating at approximately – 10°C and the vapour is adsorbed by silica gel in an air stream recycled by a blower; equal masses (up to 50 kg each) of wet herbage and silica gel are used. The system is simple to construct and is relatively inexpensive.

Approximately eight days drying time are needed to reduce moisture content from 90 to 10%. Twenty‐four different species or cultivars of both temperate and tropical grasses and legumes sampled at several stages of maturity have been dried in the system. When snap‐frozen herbage is freeze‐dried by this process the physical and chemical changes that otherwise occur when herbage is harvested and prepared for evaluation can be reduced and sufficient material can be obtained to permit animal feeding studies as well as chemical analyses.
The nature of the relationship of electronic capacitance meter readings to pastures on offer in short swards
Authors: GREATHEAD K. D. , WALLACE J. , BOULTWOOD J. N.
Published: April 2006

The residual standard deviations and distribution of residuals around five models were used to investigate the relationship between recordings from an electronic pasture probe and dry matter harvested from annual pastures (predominantly subterranean clover) at low levels of green feed on offer. Pasture material harvested was that considered to have the greatest influence on the probe i.e., within 5 cm of it.

The following conclusions were drawn. When measuring short dense green pastures yielding up to 3000 kg dry matter ha‐1 the model best describing the relationship is a split line. Curvilinear models are better than a linear model; however, both single linear and curvilinear models give biased estimates particularly near the middle and at the lower end of the range.

The best fitted model is discussed in terms of the structure of the sward and the probe.
The effect of height and frequency of mowing on the yield and composition of perennial ryegrass—white clover swards in the autumn to spring period
Authors: FULKERSON W. J. , MICHELL P. J.
Published: April 2006

Ninety‐six plots (3 × 2 m) of well‐established perennial rye grass/white clover pasture were mown to heights of 2·7 (Low) or 3·96 (High) cm (rising plate meter) at 14‐, 28‐, 84‐ or 112‐d intervals in autumn‐winter. A 7‐, 14‐ and 28‐d mowing interval was superimposed in spring on each autumn–winter mowing interval treatment with the low and high mowing heights altered to 2·92 and 4·80 cm, respectively.

With the low cutting height, accumulated herbage DM was more than doubled (1806 ± 79 kg DM ha‐1) compared to a ‘high’ (754 ± 49 kg DM ha‐1) cutting height in autumn–winter and this was due to increased harvesting efficiency rather than growth as estimated by leaf extension. Although defoliation interval had no effect on DM yield, the grass component increased and clover decreased. The composition effect carried over into spring. On average, 3·5 tillers were produced over winter for each ryegrass tiller present in autumn and tiller densities were higher in spring. Tillers produced over autumn–winter contributed more than 60% of ryegrass growth by early spring.

In early spring (16–30 September), the low cutting height increased herbage DM yield, in mid‐spring (1–14 October) it reduced DM yields particularly in combination with short defoliation intervals, while in late spring (14 October to 11 November) cutting height had no effect on DM yields.

Over the entire spring period there was a very marked effect of defoliation interval on DM yields.
The productivity of four forage legumes sown alone and with each of five companion grasses
Authors: FRAME J. , HARKESS R. D.
Published: April 2006

Four legumes—white clover cv. Blanca, red clover cvs Violetta (diploid) and Hungaropoly (tetraploid) and lucerne cv. Europe—were established as pure‐sown swards and with each of five companion grasses: timothy cv. Timo, meadow fescue cv. Bundy, sweet brome cv. Deborah and perennial ryegrass cvs Talbot (diploid) and Barlatra (tetraploid), both ryegrasses being of ‘intermediate’ heading date. Two ‘silage’ crops and an ‘aftermath grazing’ crop were harvested in each of three successive years.

In the first harvest year, total herbage DM production of red clover ranged from 15·03 to 17·01 t ha‐1. White clover and lucerne swards produced considerably less at 7·12 to 11·01 t ha‐1. In the second harvest year, lucerne swards were the highest producing at 15·54 to 17·14 t ha‐1, while DM production from red clover and white clover swards ranged from 6·75 to 11·87 t ha‐1. Lucerne swards maintained their production superiority in the third year at 16·48 to 17·87 t ha‐1, while production from white clover swards ranged from 6·41 to 10·23 t ha‐1. However, red clover swards declined to 3·30 to 5·81 t ha ‐1; this above‐average decline was mainly caused by the onset of red clover necrotic mosaic virus which affected all red clover plots uniformly in the second harvest year, and by winter conditions before the third harvest year. Total herbage DOM and CP yields of the swards were influenced in a similar manner to DM production.
A model of clostridial dominance in ensilage
Authors: LEIBENSPERGER R. Y. , PITT R. E.
Published: April 2006

A simulation model of the growth and fermentation of lactic acid bacteria and clostridia in silage is described. The model is used to predict the occurrence of a well‐preserved lactate silage or a poorly‐preserved clostridial silage. Results of the model are compared with published experimental studies not used in the model's development. The results are summarized with maps showing the combinations of initial water‐soluble‐carbohydrate content, crop buffering capacity, dry matter content, temperature, initial pH, and initial population of lactic acid bacteria which result in a clostridial silage. The specific processes modelled include the growth and death of lactic acid bacteria and clostridia; the use of substrate and accumulation of fermentation end products; release of ammonia; and change in silage pH.