bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of time of initial defoliation and height of defoliation on the productivity of perennial ryegrass swards
Authors: BINNIE R. C. , CHESTNUTT D. M. B. , MURDOCH J. C.
Published: April 2006

Over a 3‐year period the productivity of perennial ryegrass (Lolium perenne L., cv. S24) swards as influenced by variations in the time of initial defoliation and close (2·5 cm) and lax (8 cm) defoliation was studied. Treatments with initial defoliations in the early vegetative stage, stem elongation and flowering stages of growth gave higher annual yields than treatments in which the initial defoliation was taken at an intermediate stage of growth when the majority of the stem apices had just been elevated above the height of defoliation. Initial defoliation treatments which removed a high proportion of apical meristems while the yield at the initial defoliation was still low produced the lowest annual yield. Consistent lax defoliation reduced yield by 14·5% compared with continual close defoliation. However, taking an initial lax defoliation followed by subsequent close defoliations produced a slight yield advantage of 4·8% over consistent close defoliation. The results are discussed in relation to other research findings and the practical implications commented upon.
The effect of supplements of fishmeal and lactic acid on voluntary intake of silage by calves
Authors: THOMAS C. , GILL M. , AUSTIN A. R.
Published: April 2006

In order to assess the relative effects of protein content and acid on intake, grass silage was given ad libitum to twelve entire male calves, initially 4 months of age and 117 kg liveweight (LW), either alone or supplemented with fishmeal at 50 g dry matter (DM) per kg silage DM. These two diets were offered alone or with additions of lactic acid at 50 g per kg silage DM in a partial changeover design in which lactic acid levels only were reversed between two 28‐d measurement periods.

In the absence of lactic acid, fishmeal significantly increased absolute intake but not intake relative to LW. There was a significant interaction between treatments in that the addition of lactic acid depressed DM intake in the absence of fishmeal (23·9 vs 21·1 g kg‐1 LW) but not in its presence (23·2 vs 23·1 g kg‐1 LW). Addition of fishmeal increased the digestibility of DM from a mean of 0·708 to 0·744 (P < 0·05), of gross energy from 0·646 to 0·694 (P < 0·01) and of N from 0·422 to 0·592 (P < 0·001) but had no significant effect on the digestibility of cellulose (0·766 vs 0·788 for treatments without and with fishmeal respectively). Lactic acid addition had no effect on the digestibility of plant components and, further, interaction effects between treatments were not significant. Supplementation with fishmeal reduced the total time spent eating and ruminating (Ro value) from a mean of 284 to 240 min kg‐1 DM (P < 0·01) and increased urine pH from 8·34 to 8·50. Lactic acid influenced neither Ro value nor urine pH and the interaction effect did not reach significance for these two parameters.

The results indicate that the addition of fishmeal can overcome a depressant effect of lactic acid on intake and it is suggested that the responses to treatment were mediated via changes in the ratio of energy to protein supply rather than as a result of treatment effects on digestive efficiency or acid‐base balance.
Effect of herbage allowance on the efficiency of defoliation by the grazing animal
Authors: STUTH J. W. , KIRBY D. R. , CHMIELEWSKI R. E.
Published: April 2006

An experiment examining the relationship of daily herbage disappearance (DHD) and daily herbage allowance (DHA) is described. Cows with calves were grazed at three stocking rates on Kleingrass and Coastal Bermudagrass pastures. DHD and DHA were monitored at 14‐d intervals. A significant positive linear relationship was noted between DHD and DHA (P0·25). Equations derived for Coastal Bermudagrass and Kleingrass were not significantly different and resulted in a combined equation Ŷ= 0·275X + 0·209 with an r2 vaiue of 0·27. As DHA exceeded 6–9 kg DM per 100 kg live weight, efficiency of defoliation by the cows and calves declined.
Variations in herbage mass and digestibility, and the grazing behaviour and herbage intake of adult cattle and weaned calves
Authors: HODGSON J. , JAMIESON W. S.
Published: April 2006

Two experiments are described in which groups of lactating cows, non‐lactating cattle and weaned calves grazed a sequence of swards varying in maturity and herbage mass under strip grazing management at a daily herbage allowance of 60 g dry matter per kg live weight. Lactating cows ate 43% and 76% more herbage than non‐lactating cattle of similar weight in the two experiments but herbage OM intakes per unit live weight by the calves and lactating cows were similar.

Variations in diet digestibility and herbage intake in the lactating and non‐lactating cattle with changes in sward conditions were similar. In the first experiment the calves were experienced grazers; the variation in the digestibility of the herbage selected was less in the calves than the adult cattle, but the variation in herbage intake was greater. The calves in the second experiment were younger, and they were inexperienced grazers; their ability to increase herbage intake in response to changing sward conditions was poorer than that of adult cattle, though variations in diet digestibility were similar in all classes.

The practical implications of these results are discussed briefly.
An investigation of problems of sward improvement on deep peat with special reference to potassium responses and interactions with lime and phosphorus
Authors: FLOATE M. J. S. , RANGELEY A. , BOLTON G. R.
Published: April 2006

In experiments to determine the minimum fertilizer requirements for improved pasture on deep peat, yields were initially low and declined rapidly. Within 2 years persistence of sown species was poor when only 2·5 t lime ha‐1 was applied. Analytical data suggested that K deficiency and low soil pH were contributory factors. When K was omitted from a composite nutrient solution, clover yield was reduced by 50% when 2·5 t lime ha‐1 was applied but was not significantly reduced with 5·0 t lime. Clover alone produced little response to either P or K separately, but highly significant positive interactions were recorded. Clover, but not ryegrass, responded to K topdressing in field cut‐herbage experiments. There was a 3‐fold increase in ryegrass yield with combined P and K topdressing under grazing; 10 times more N and K were recycled in urine on this treatment than on the control.

It was concluded that at least 5·0 t lime, 60 kg P and 80 kg K ha‐1 are required for pasture establishment and that soil pH should be maintained above 5·0 to minimize K requirements. The significance of nutrient cycling and of lime × K and P × K interactions is discussed in relation to the persistence of sown species and the maintenance of improved swards on deep peat.
Competitive effects between ten cultivars of perennial ryegrass and three cultivars of white clover grown in association
Authors: CAMLIN M. S.
Published: April 2006

In an experiment of four years duration, the competitive relationships between three cultivars of white clover (Trifolium repens L.) and ten cultivars of perennial ryegrass (Lolium perenne L.) were studied under a N fertilizer regime of 200–240 kg ha‐1 a‐1. The clover cultivars were selected to embrace the various leaf sizes from medium large to small and the ryegrasses included early, mid‐season and late cultivars with a known range of persistence.

During the experiment there was a progressive decline in the contribution of clover, though the different characteristics of each of the clover and ryegrass cultivars produced substantial deviations from the average trend. The clover cultivar Kersey was significantly more aggressive towards the companion grass cultivars than either S100 or S184. It produced consistently greater clover contribution to total yield than the other two cultivars and significantly depressed the yields of some of the companion grass cultivars. There was evidence that compatibility of the ryegrass cultivars with clover was inversely related to persistence; the non‐persistent ryegrass cultivars S321 and Presto consistently produced lower grass yields than the more persistent cultivars and consequently permitted greater clover contribution. In the second and third years yield substitution effects between clover and grass components substantially reduced differences in the total grass‐clover yield.

The interactions revealed in the experiment showed that both ryegrass and clover cultivars have the potential to influence each other when in association although, with minor exceptions, total annual yields were similar for all grass and clover mixtures at the moderately high level of N applied.
Variation in forage yield and quality of three cruciferous catch crops grown in southern England
Authors: SHELDRICK R. D. , FENLON J. S. , LAVENDER R. H.
Published: April 2006

Cruciferous catch crops are an important source of forage, particularly in sheep systems, but due to their late sowing date, commonly July or early August, soil moisture is often a limiting factor in crop establishment and subsequent growth, causing wide variations in yield from year to year. Crops of stubble turnip (Brassica campestris ssp. rapifera), forage rape (B. napus ssp. biennis) and fodder radish (Raphanus sativus) were grown at Hurley between 1969 and 1977. Fodder radish was the most variable in dry matter (DM) yield, while stubble turnip was the most stable. Both DM yields and in vitro digestibilities rose during the autumn, reaching a maximum in mid‐December for stubble turnip and forage rape, and in mid to late November for fodder radish. Yield and digestibility subsequently declined. The N concentrations of the forages exhibited a contrary trend, reaching minimum values at about the time of the highest DM yields. The gradual changes in crop quality suggest that the crops are well suited to grazing utilization, in which management is simplified if crop quality shows little variation.
The herbage intake and performance of set‐stocked suckler cows and calves
Authors: BAKER R. D. , LE DU Y. L. P. , ALVAREZ F.
Published: April 2006

Groups of eight Hereford × Friesian cows and their South Devon cross calves were set stocked over a 24‐week grazing season at 3·23 (low), 3·21 (medium) or 4·24 (high) cows ha‐1 together with their calves. For the first 8 weeks only two‐thirds of the total area was grazed. Increasing the stocking rate from low to medium reduced daily milk yield and cow and calf liveweight gains by 1·2, 0·24 and 0·29 kg d‐1 respectively, and from medium to high by 1·2, 0·24 and 0·23 kg d‐1. The main sward factor influencing faecal output and herbage intake was the quantity of organic matter on the pastures but the digestibility of the herbage selected also exerted a significant effect on the intake of cows. Major depressions in the herbage intake of cows occurred once the average sward height fell below 7 cm. Output of calf live weight was 628, 658 and 743 kg ha‐1 for the 3 stocking rates from low to high, and for cows 246, 179 and 30 kg ha‐1. It was concluded that decisions on pasture management should be taken in relation to the cow rather than the calf on set‐stocked swards.
A comparison of indirect methods of estimating feed intake on pasture
Authors: WANYOIKE MARGARET M. , HOLMES W.
Published: April 2006

The data from 12 individual cattle grazed on a uniform sward were used to compare field sampling of faeces with three time‐schedules for rectal sampling of faeces. Estimates of digestibility from a faecal nitrogen equation were compared with estimates based on in vitro digestibility, or modified acid‐detergent fibre determinations, on clipped herbage samples.

Field sampling gave a lower coefficient of variation (8%) in chromic oxide content than did grab sampling (14%). Grab sampling introduced an upward bias in estimates of faecal output compared with field samples. The estimate of digestibility based on the faecal index was intermediate to those based on clip samples from the upper and lower horizons of the sward. There was no difference in the mean digestibilities estimated from in vitro or MAD fibre.
Establishment, persistence and nitrogen fixation of white clover and marsh trefoil on blanket peat
Authors: LAIDLAW A. S.
Published: April 2006

White clover (cv. S184 or Blanca) or marsh trefoil (cv. Grasslands 4703 or Grasslands Maku) were sown alone and in combination with a companion grass (tall fescue, red fescue, perennial ryegrass or ryegrass cleanings) on a peat area of hill land originally dominated by Juncus articulatus and Molinia caerulea.

Lime and ground rock phosphate were applied in 1973, the area rotavated to a shallow depth and seeds sown in May 1974. No fertilizers were applied except at sowing time and two harvests were taken per annum for 4 years.

Differences in yield and legume content between companion grass treatments were small. After the first full harvest year Blanca swards usually had the lowest DM yields and those containing Maku the highest. The contribution of marsh trefoil to total herbage yield increased from 4·2% in 1975 to 22% in 1978, whereas white clover decreased from 4·2 to 1·2%. Legume yields in 1978 were less than half those in 1977. Overall, N yields were low, Maku swards fixing most N estimated to be highest in 1977 at 35 kg ha‐1.

It is concluded that marsh trefoil grows well on upland peat but more information on its response to grazing is necessary before conclusions can be drawn about its value in hill land improvement.
The digestibility of herbage selected by oesophageally fistulated cows, steer calves and wether sheep when strip‐grazing together
Authors: LE DU Y. L. P. , BAKER R. D.
Published: April 2006

The digestibility of herbage selected by dairy cows, milk‐fed calves, weaned calves and wether sheep was examined on four occasions each day as they strip‐grazed together a daily allocation of herbage. The average quality of the material selected by each group was similar. Organic matter digestibility of the herbage selected declined from 0·274 to 0·223 as the average height of the sward fell from 16 to 6 cm; this decline was slightly more rapid for the cows than for the other stock. A similar trend was also evident in samples cut from the sward to simulate the horizon removed prior to each sampling time.
Productivity of red clover grown alone and with companion grasses over a four‐year period
Authors: McBRATNEY J. M.
Published: April 2006

Six red clover cultivars, three diploid—Essex, Sabtoron and Violetta—and three tetraploid— Teroba, Red Head and Hungaropoly—were sown alone and with each of three companion grasses—timothy (S48), tall fescue (S170) and perennial ryegrass (S24). The productivity and persistency of the red clover cultivars were compared over 4 years. Dry matter (DM) yield, DM digestibility and the crude protein (CP) concentration were assessed and botanical analyses conducted on herbage samples from each treatment at each of three harvests per annum. Annual fertilizer application consisted of 165 kg P and 312 kg K ha‐1.

Comparing clover cultivars alone Essex was significantly less productive and less persistent than the other five cultivars. Yield and persistency of the five other cultivars did not differ markedly within years with the exception that the diploids were significantly less productive than the tetraploids in the fourth year. Over all 4 years mean annual total DM and clover DM yields of the five cultivars were between 12·2 and 13·2 t ha‐1 and between 9·2 (79·2% of total DM yield) and 10·2 (83·2%) t ha‐1 respectively, and differences were not significant.

Up to the end of the third year there was little or no advantage gained by the inclusion of a companion grass, annual total DM yields being between 11·2 and 14·2 t ha‐1 for clover alone and between 10·2 and 14·2 t ha‐1 for clover‐grass mixtures. In the fourth year there was an overall tendency for the yield of the clover alone to be lower, between 7·2 and 12·2 t ha‐1, than that of the clover‐grass mixture, between 8·2 and 13·2 t ha‐1, and this was more pronounced with the diploid than with the tetraploid clover cultivars. Sown with companion grasses, Essex and Hungaropoly were lower in yield and in contribution than the other cultivars over the 4 years. The influence of the companion grass on total dry matter yield showed that the contribution of timothy was low relative to that made by tall fescue and perennial ryegrass. Perennial ryegrass made the most varied contribution from year to year. Tall fescue was the most consistent contributor with all clover cultivars and at the end of 4 years both yield and clover‐grass balance had not changed materially.

No pronounced differences in DM digestibility were evident between treatments.

Crude protein concentration of the pure clover was similar to that of the clover‐timothy treatments and both would appear to be superior to either the clover‐perennial ryegrass or clover‐tall fescue mixtures.

It is considered that red clover dominant swards are suitable for use under a cutting regime and can provide high yields of DM at a low cost for up to 4 years. Such swards are self‐sufficient in N and in addition soil N accumulation can be exploited in the production of succeeding crops.
A comparison of a hybrid stubble turnip (cv. Appin) with other cruciferous catch crops for lamb fattening. 1. Initial evaluation for dry matter yield and forage quality
Authors: SHELDRICK R. D. , LAVENDER R. H.
Published: April 2006

A novel hybrid stubble turnip, Appin, bred by the Scottish Plant Breeding Station (Brassica campestris ssp. rapifera cv. Tigra ×B. campestris ssp. nipposinica cv. Mizuna) was compared in small‐plot cutting trials with stubble turnip (B. campestris ssp. rapifera cv. Ponda), forage rape (B. napus ssp. biennis cv. Canard) and fodder radish (Raphinus sativus cv. Neris) for 3 years, 1975–77, samples being taken from October to December or January each year to cover the likely period of utilization by grazing lambs. Except for the first year, Appin proved to yield less DM than Ponda, and be inferior in digestibility and metabolizable energy (ME) content, though N contents were on occasion higher. Canard had the highest overall ME content. In dry conditions in autumn 1977, Ponda proved the more reliable crop, suffering less depression in yield than other species. Anti‐metabolite contents were determined in freeze‐dried samples taken in winter 1976‐77 and showed Canard to have the most brassica anaemia factor (S‐methyl cysteine sulphoxide): contents of thiocyanate were generally similar between crops.

As the degree of utilization of such forages when grazed can outweigh differences in recorded above‐ground DM yields from cutting trials, it was considered that claims of better root anchorage and hence better utilization for Appin warranted evaluation in a grazing trial.
Sward growth under cutting and continuous stocking managements: sward canopy structure, tiller density and leaf turnover
Authors: JONES M. B. , COLLETT B. , BROWN SIAN
Published: April 2006

The change in structure of continuously grazed versus infrequently cut swards of perennial ryegrass (Lolium perenne L), cv. S23, was investigated during their first full harvest year. Measurements were made from early May until late September. The intensity of stocking by sheep in the grazed sward was adjusted in an attempt to maintain a high level of radiation interception and the cut sward was harvested at approximately monthly intervals.

The herbage mass, lamina area index and radiation interception of the cut sward varied in a cyclic pattern between harvests but in the grazed sward these parameters showed considerably less variation, although they all increased early in the season and then declined later. The proportion of dead material above ground increased throughout the season in both sward types but was more marked in the grazed sward.

There were major differences between the grazed and cut swards in the number of tillers per unit ground area; the difference became more marked throughout the season and by September the tiller densities in the grazed and cut swards were 3·204 m‐2 and 6·203 m‐2 respectively. Divergence in tiller density was associated with differences in specific stem weight and leaf area per tiller.

Rates of appearance and death of leaves on tillers in the grazed sward were determined. During May, leaf appearance exceeded leaf death but this was reversed in June. During the rest of the season as a new leaf appeared on a tiller so the oldest leaf died.
Slot‐seeding investigations. 2. Time of sowing, seed rate and row spacing of Italian ryegrass
Authors: HAGGAR R. J. , SQUIRES N. R. W.
Published: April 2006

Italian ryegrass was slot‐seeded into permanent grass in two field experiments at Oxford. In the first experiment August and September proved to be the most reliable months for slot‐seeding, with April as a possible alternative. A row‐spacing experiment showed that the optimum distance between rows was about 30 cm; seed rate in the row had a lesser influence on increasing herbage growth. In both experiments slot‐seeding did not result in any substantial change in earliness of growth or alter total herbage harvested but it did even out the seasonal distribution of growth, particularly by increasing it in the following July.
Evaluation of propionic acid‐treated hay as a feed for growing sheep
Authors: DAVIES M. H. , WARBOYS I. B.
Published: April 2006

Two experiments were carried out to evaluate propionic acid‐treated hay as a feed for sheep in which eighteen ewes (experiment 1) and eighteen ewe lambs (experiment 2) were fed ad libitum on hay only. At feeding, the propionic acid‐treated hays had higher D‐values and water‐soluble carbohydrate concentrations, but a lower dry matter concentration, than the untreated hays. The voluntary feed intake and liveweight gain of the sheep fed on two acid‐treated hays and on an untreated hay in experiment 1 were similar. In the second experiment an acid‐treated moist hay was eaten in greater amounts by the sheep and liveweight gains were greater than on the corresponding untreated hay, but were not significantly different from those of sheep fed on field‐cured hay.
The diet ingested by sheep grazing swards differing in white clover and perennial ryegrass content
Authors: MILNE J. A. , HODGSON J. , THOMPSON R. , SOUTER W. G. , BARTHRAM G. T.
Published: April 2006

A series of twenty‐four swards containing different proportions of white clover (0·20‐0·25) and perennial ryegrass were created by using different seed mixtures, herbicide applications and previous cutting Frequencies. These swards were used to study the diet of oesophageally‐fistulated wether sheep which grazed the various swards for a 30‐min period after 1, 2 and 3 weeks of regrowth.

The proportion of white clover in the diet was generally greater than that in the sward. Fifty‐seven percent of the variation in the proportion of white clover in the diet could be attributed to the proportion of white clover in the sward. White clover and perennial ryegrass leaf and stem were grazed to the same height and the proportion of white clover in the grazed horizon of the sward explained 83% of the variation in the proportion of white clover in the diet. The proportion of white clover in the diet was greater than the proportion in the grazed horizon of the sward in week 3 of regrowth, but not in weeks 1 and 2, and greater when the proportion of white clover in the grazed horizon was lower than 0·20. Both these observations were interpreted as indicating selection for white clover by the sheep within the grazed horizon.

There was a positive and linear relationship between the depth of the grazed horizon and sward height which, together with the relationship between the proportion of white clover in the grazed horizon and in the diet, would allow the prediction of the proportion of white clover of the diet from the height and the white clover content of the grazed horizon of the sward.
Soil moisture and growth of contrasting varieties of Lolium, Dactylis and Festuca species
Authors: NORRIS I. B.
Published: April 2006

Varieties of Italian, perennial and Italian × perennial ryegrasses, tall fescue and cocksfoot were used to determine the effects of soil moisture on grass growth. Weather conditions were monitored and herbage accumulation, leaf extension rate, leaf appearance rate and tillering were recorded under natural (control), covered and irrigated treatments.

Water deficit reduced crop growth rate in the spring and drought was the major factor influencing crop growth rates in all varieties during the summer. The ryegrasses appeared most sensitive to drought, and particularly poor recovery growth was exhibited by the Italian ryegrass RvP and the hybrid ryegrass Snowdon.

Leaf extension rate and leaf appearance rate were both reduced by increasing soil water deficit. Herbage accumulation was increased by irrigation when potential soil water deficits were greater than 100 mm. When water deficits were large, irrigation increased leaf extension more than leaf appearance or tiller number. Increasing moisture deficit had a greater effect upon tiller number than on leaf extension.
The influence of selected agronomic factors on the yield of forage peas
Authors: POTTS M. J.
Published: April 2006

Five trials were carried out in 1979 to assess the influence of cultivar, seed rate, fertilizer application and the inclusion of oats as a companion crop on the dry matter (DM) yield of forage peas grown in the west of Scotland. Despite the season being abnormally cold the crop consistently produced between 6 and 8 t DM ha‐1. There was little difference between cultivars in the yield of forage produced but there were considerable differences in the time taken to reach maturity. All cultivars lodged. There was no yield response to seed rate of between 80 and 280 kg ha‐1 nor to fertilizer N and K applications. The inclusion of oats in the seeds mixture greatly reduced lodging and had no marked effect on DM yield but the organic matter digestibility and crude protein concentration were lower than recorded for peas grown alone in previous years.
Relationship between competitive ability and yielding ability in mixtures and monocultures of populations of Dactylis glomerata L
Authors: EAGLES C. F.
Published: April 2006

Swards were developed from plants of contrasting populations of Dactylis glomerata L. selected for high and low dry‐matter (DM) production in monocultures and mixed cultures grown during 1970 and 1971. DM production of these mono‐genotype swards was assessed during 1974. Those swards developed from the divergent selections from monocultures maintained a significant difference between the high and low selections, whereas those developed from selections out of mixed cultures showed no significant difference in yield. These results are consistent with earlier reports that there is no positive relationship between competitive ability in mixed cultures and vigour in pure stands. The implications of the physiological basis of these responses in terms of grass breeding are discussed.
A comparison of the nutritive values of early and late varieties of timothy
Authors: MÍKA V.
Published: April 2006

In vitro digestibility, fibre, lignin and protein were determined in 50 varieties of timothy differing markedly in maturity date. The grasses were field‐grown as single plants and were sampled at 10% ear emergence, 30% flowering and the mature seed stage and were compared in four groups according to date of ear emergence.

Significant differences were found between maturity groups in digestibility and protein concentration particularly at the earlier growth stages. Considerable variation also occurred within maturity groups. Differences in digestibility, fibre, lignin and protein were significantly correlated with the number of days between 30 April and harvest date.

The results are discussed in the context of an appropriate evaluation scheme for timothy varieties.
Productivity of mixtures of Italian ryegrass and red clover
Authors: CAMLIN M. S. , GILLILAND T. J. , STEWART R. H.
Published: April 2006

Two red clover (Trifolium pratense) cultivars, Red Head (tetraploid) and Kuhn (diploid), were sown at a seed rate of 13 kg ha−1 either alone or in mixture with Italian ryegrass (Lolium multiflorum) cv. RvP sown at seed rates of 10, 15, 20 or 30 kg ha−1. RvP was also sown alone at a seed rate of 30 kg ha−1 and received nil or 300 kg ha−1 fertilizer a−1 fertilizer N. All plots were established using the barley cultivar Midas sown at a seed rate of 100 kg ha−1 as a nurse crop.

Neither clover cultivar nor ryegrass seed rate significantly influenced either dry matter harvested or botanical composition over the 3 harvest years. On average over all years the grass‐clover mixtures produced 75% of the yield of the N‐fertilized RvP, 125% of the clover monocultures and 225% of the unfertilized RvP. The red clover contribution to the total dry matter harvested of the mixtures averaged 45–60%. The dry matter concentrations of the mixtures were considerably higher than those of the pure clover stands. In the third year yields were markedly reduced in comparison with those in the first and second years.

It was concluded that Italian ryegrass can be a suitable companion grass for red clover. Its superior yielding capacity over other grasses such as perennial ryegrass or timothy under a conservation management can be coupled to advantage with red clover to give a sward which Is essentially stable, at least over a 2‐ to 3‐year cropping period, although giving slightly reduced yields in the third year. Italian ryegrass‐red clover mixtures, without the use of fertilizer N, can produce high DM yields of good quality herbage.
The influence of water content on the stiffness and fracture properties of grass leaves
Authors: VINCENT JULIAN F. V.
Published: April 2006

Laminae of Lolium perenne and Phleum pratense were tested mechanically and the results analysed using engineering composite theory and fracture mechanics. As the lamina dries the fibres double in stiffness. The intervening cells show a sevenfold increase in stiffness below 20% water content (based on dry weight). Work to fracture across the veins is almost independent of water content, but below 50% water content the mode of fracture changes. It is predicted that total fibre content will not affect hay shatter; total protein content may affect it by altering the water‐binding properties.
Effects of the amount of barley and time of access to grass silage on the voluntary intake, eating behaviour and production of dairy cows
Authors: HARB M. Y. , CAMPLING R. C.
Published: April 2006

Three separate changeover experiments were conducted to investigate the effect of the amount of rolled barley and time of access to silage on the voluntary intake, eating behaviour and production of dairy cows. In Experiment 1, twenty‐four milking cows were used to compare the effect of 4 1 and 6 1 kg d−1 rolled barley on voluntary intake and milk production. In Experiment 2, fourteen cows were used in a comparison of the effect on voluntary intake and milk production of 5‐ and 22‐h access to silage. Experiment 3 measured the effects on intake of silage of 2 and 4 kg d−1 rolled barley and of 5‐ and 22‐h access to silage. In Experiment I, increasing the amount of barley eaten reduced intake of silage by 0–50 kg dry matter (DM) per kg barley DM but in Experiment 3 with 5‐h access to silage there was no significant difference between the amounts of silage eaten with 2 and 4 kg d−1 barley. However, in Experiment 3 when allowed 22‐h access to silage, the replacement rate was 0–53 kg DM silage per kg DM barley. Increasing access from 5 to 22 h increased silage intake by 37% in Experiment 1 and by 27% in Experiment 3. Milk yield was significantly increased by 4% when extra barley was given in Experiment 1 but there was no significant effect in Experiment 3. Increasing the time of access to silage led to an 11% increase in milk yield in Experiment 2 but there was no significant effect in Experiment 3. There was much variation between cows in the depression of silage intake per kg change in barley DM eaten with coefficients of variation of 131% and 109% in Experiments 1 and 3, respectively. When allowed access to silage for 22 h daily, on average, each cow spent 180 min eating silage in ten meals, although there was appreciable variation between cows in eating behaviour. The amount of barley did not affect the cows' rate of eating silage nor the duration of eating.
A model of the anaerobic phase of ensiling
Authors: NEAL H. D. ST C. , THORNLEY J. H. M.
Published: April 2006

A model of ensiling is described which incorporates the interactions of lactic acid bacteria and Clostridia with water soluble carbohydrates. The processes modelled include bacterial growth, the production of lactic and butyric acids from water soluble carbohydrates, and the conversion of lactic acid to butyric acid. The calculation of pH, and the regulation of bacterial activity by pH are important components of the model. The model predicts time courses for pH and the five State variables, which are the concentrations of water soluble carbohydrates, lactic acid, butyric acid, lactic acid bacteria and Clostridia. There is good qualitative agreement between the predictions of the model and experimental data on ensiling.
Putting an economic value on increases in grass production
Authors: DOYLE C. J. , ELLIOTT J. G.
Published: April 2006

An attempt was made to determine monetary values for grass which might be used by researchers to assess the likely economic implications of their findings. It is shown that the value of extra grass production will vary considerably depending on the use made of it. At 1982 price levels, estimated values for grass in the field ranged from 1–4 to 10–6 pence kg−1 DM, with a modal value around 3–5 pence kg−1 DM. At the same time, the seasonal distribution of the extra grass production is important since the value of extra grass at different points in the growing season may vary markedly. The way in which these values for grass may be used is illustrated, using as an example weed control during sward establishment. Finally, the sensitivity of investment returns to changes in the value placed on grass is discussed. Extreme caution is necessary in drawing general conclusions about benefits and costs from an evaluation based on a specific value for grass.
Sward structure changes within a perennial ryegrass swara: leaf appearance and death
Authors: VINE D. A.
Published: April 2006

The appearance of successive leaves on labelled tillers of S24 perennial ryegrass, and their subsequent death, were monitored for 1 year on cut plots on which four levels of N fertilizer were applied.

A new leaf appeared about once every 15 d from the end of April until the beginning of September, and about once every 52 d from the end of October to the middle of February. Rate of appearance changed rapidly during September and October, and again from mid‐February until the end of April. The response of leaf appearance rate to temperature changed early in the year; the effect of overwintering is discussed.

Leaf lifespan was 50–60 d in summer and 120–140 d in autumn and early winter, and was influenced by conditions either during expansion of the leaf or shortly afterwards.

The results are discussed in relation to the construction of a model to describe changes in the herbage available to animals grazing a grass sward.
The effects of spring closing date on the yield and quality of perennial ryegrass and cocksfoot cut for conservation
Authors: SWIFT G. , EDWARDS R. A.
Published: April 2006

This second paper concerned with effects of prolonged spring defoliations on two early perennial ryegrass varieties (Cropper and RvP Hay Pasture), an intermediate perennial ryegrass (Talbot) and an early cocksfoot (Roskilde) examines the effects of different closing dates on ear emergence, weekly DOMD (in vitro) and conservation yields. The grasses were mown fortnightly to simulate sheep grazing from January until three closing dates, 19 April, 3 May or 17 May, in 1978 and 1979. A set of plots was left undefoliated. All plots were sampled weekly from 2 or 3 weeks after 17 May until the end of June or early July.

Prolonged mowing resulted in a small delaying effect on 50% ear emergence of the ryegrasses. The maximum delay was 3 d with the latest closing date. Under this treatment, ear emergence of the cocksfoot was delayed by an average of 12 d but by only 0–4 d under the earlier closing dates. Delay in date of closing caused a significant delay in the time to reach a given DOMD but the effect was largely confined to the latest closing date and was greatest for the cocksfoot. The time when 670 g kg−1 DOMD was reached was delayed in the ryegrasses by no more than 5 d, except for a 12‐d delay in the intermediate ryegrass in 1978 following the late closing date. Under this treatment the delay for the cocksfoot was 8 d in both years. The early ryegrasses produced stemmy regrowths.
The integration of conservation with grazing for milk production: a computer simulation of the practical and economic implications
Authors: DOYLE C. J. , CORRALL A. J. , THOMAS C. , LE DU Y. L. P. , MORRISON J.
Published: April 2006

Earlier studies have concluded that for a dairy enterprise the most profitable conservation strategy, where cutting and grazing areas are separate, is generally associated with relatively low‐digestibility silage. The aim of this study has been to investigate whether this conclusion remains true where cutting and grazing are integrated. A mathematical model of grass production and utilization by a dairy enterprise has been developed from information collected from a variety of experimental sources. It was found that cutting strategies aimed at making low‐digestibility silage could not automatically be regarded as the most profitable. In good grass‐growing conditions strategies resulting in low‐digestibility silage did appear to offer the highest gross margins per unit area, but under average and poor growth conditions the greatest profits were associated with high‐digestibility silage strategies. In particular, it was noted that the timing and frequency of conservation cuts influenced the efficiency with which grass could be utilized on the grazing areas and this fact rather than yield of conserved material influenced the comparative biological and economic efficiency of the different cutting strategies.
The antimicrobial spectra of some salts of organic acids and glutaraldehyde in respect to their potential as silage additives
Authors: WOOLFORD M. K.
Published: April 2006

Salts of formic, acetic and propionic acids and glutaraldehyde were subjected to an assay with representatives of the major groups of silage micro‐organisms at pH 4·0, 4·5, 5·0 and 6·0. The antimicrobial spectra of the salts suggested that they are most effective against the least desirable components of the bacterial flora of silage, coliforms, Clostridia and bacilli, and would create conditions for a desirable fermentation in practice. In many instances the activity of the salts was better than the corresponding free acid and it was postulated that, if supplemented with acid, aerobic stability of silage might also be improved. Glutaraldehyde, whilst being less selective as an antimicrobial agent, possesses properties which would encourage a lactic‐acid fermentation in silage.
Silage and milk production: a comparison between concentrates containing different amounts of protected protein as supplements for silage of high digestibility
Authors: CASTLE M. E. , WATSON J. N.
Published: April 2006

Grass silage made in late May from S24 perennial ryegrass was offered ad libitum to eight Ayshire cows in a 16‐week feeding experiment. The silage had a DM concentration of 244 g kg−1, contained 163 g crude protein (kg DM)−1 with a ruminal degradability of 0.77 and had an in vitro DOMD concentration of 678 g kg−1. In addition, four concentrates each containing 167 g soya‐bean meal kg−1 were consumed at a mean daily rate of 6.43 kg DM per cow. The soya‐bean meal was either untreated, or ‘protected’ by formalin and mixed in the following proportions, 100:0; 66:34; 34:66; and 0:100 respectively, in the four concentrates. The daily intakes of silage DM were not significantly different on the four treatments and averaged 90 kg DM per cow, giving a mean total daily DM intake of 32.4 g kg−1 live weight. The milk yields were not significantly different on the four treatments and averaged 23.9 kg −1 The treatments had small and non‐significant effects on milk composition and live weight. It is concluded that with a high‐digestibility, well‐preserved grass silage of satisfactory protein content the inclusion of ‘protected’ protein in the supplementary concentrate had no beneficial effects on milk production.
Productivity of red clover grown alone and with companion grasses; further studies
Authors: McBRATNEY J. M.
Published: April 2006

Three diploid—Sabtoron, Violetta and Essex—and three tetraploid—Hungaropoly, Teroba and Red Head—red clover cultivars were sown alone and with each of three companion grasses—timothy (S48), tall fescue (S170) and perennial ryegrass (S24). The productivity and persistence of the red clover cultivars were compared. Results obtained over the first four harvest years were presented in an earlier paper (McBratney, 1981) and this paper presents results from the fifth and sixth (final) harvest years.

The low yield obtained in the fifth and sixth year from Essex under each seeding treatment indicated a deterioration in its persistency or vigour or both. In the fifth year the remaining two diploids, Sabtoron and Violetta, were as highly productive and persistent as the three tetraploids but in the sixth year the decrease in productivity was greater in the diploids than in the tetraploids. In the fifth year Teroba, the highest yielder, produced 9 8 t total DM ha−1 over all seeding treatments of which 73% was clover DM; in the sixth year Teroba was again highest yielding, producing 9.3 t ha−l with 67% clover content. Tall fescue was the most consistent companion grass in the mixed swards, in the sixth year contributing 53% grass DM to the total 8 8 t DM harvested ha−1.

The trial demonstrates the potential of a number of red clover cultivars grown either pure or with a suitable perennial grass to achieve and maintain a high output of herbage of good quality over a period of 6 years without any application of fertilizer N. The practical agricultural implications of using red clover are discussed.
Herbage yield and animal production from grassland on three commercial dairy farms in South‐East England
Authors: PEEL S. , MATKIN ELIZABETH A.
Published: April 2006

Yields of grass were measured on three dairy farms in 1981. Farm 1, on free‐draining loamy soil over chalk, produced 10.3 t DM ha−1 using 336 kg N ha−1. Farm 2, on poorly‐drained loam over Oxford clay, produced 12.8 t DM ha−1 using 354 kg N ha−1. Farm 3, on loam over clay with some free‐draining sandy loam, produced 9.5 t DM ha−1 with 169 kg N ha−1. Allowing for differences in soil nitrogen and summer rainfall these yields were quite close to expectations from experimental results, despite considerable poaching damage to some swards.

Animal production records were kept and all livestock were weighed every 6 months, so as to calculate the utilized metabolizable energy (UME) output from grassland on each farm. These were 73, 62 and 59 GJ ha−1 on farms 1, 2 and 3 respectively.

The UME output, expressed as a proportion of the yield of grass (converted to ME), was taken as the ‘efficiency of utilization’ of grass. This was 70% on farm 1,44% on farm 2 and 58% on farm 3. Results are presented separately for the summer and winter 6 months. Utilization by grazing appeared to be markedly reduced under very wet soil conditions. Major losses occurred in the conservation of grass.

The results begin to establish a valuable base of data from commercial farms.
The influence of seed rate and pesticides on the establishment and growth of white clover slot‐seeded into a permanent pasture
Authors: WILLIAMS E. D.
Published: April 2006

The establishment and growth of white clover (cv. Grasslands Huia) was investigated in two experiments with seeds sown in slots cut in old permanent pasture in early May 1982. In the first experiment, fully protected from pests and diseases, either 50 (low), 100 (medium) or 200 (high) seeds were sown evenly per metre length of slot; 100 seeds were also sown in a clumped pattern unevenly. In the second experiment, the effects of various combinations of molluscicide, insecticide and fungicide were investigated.

Nine weeks after sowing there were 27, 37, 34 and 62 seedlings m−1 on the low, medium even, medium uneven and high seed‐rate treatments, representing percentage establishments of 54, 37, 34 and 31 respectively. By September, however, there were no significant differences between the dry weights m−l of any of the treatments. In the second experiment, damage by slugs occurred early in treatments without molluscicide and caused a mean reduction of 70% in seedling establishment. As a result significantly smaller dry weights m−1 of clover were recorded in September in these than in other treatments. Failure to protect against insects resulted in smaller seedlings.

The results indicated that variations in seed rate within the range investigated were not critical but that failure to protect against pests decreased percentage establishment and subsequent growth.
The effect of time of harvest on seed production of three red clover cultivars
Authors: PURI K. P. , LAIDLAW A. S.
Published: April 2006

Small plots of red clover cv. Sabtoron, S123 (diploids) and Hungaropoly (tetraploid) were harvested for seed production at two‐week intervals from 19 August to 17 October inclusive in 1981, inflorescence appearance rate, bee density and components of yield having been monitored throughout the summer. Inflorescence appearance rate reached a maximum at the end of July/early August for Hungaropoly and Sabtoron and during mid‐August for S123. Bee density followed a similar pattern. Florets and seeds per inflorescence and 1000‐seed weight decreased as flowering progressed except during the first three weeks in July. Potential seed yield was calculated from the components of yield for the harvests taken on 3 and 18 September. Losses in seed yield (difference between actual and potential) up to and during harvesting, threshing and cleaning were lower in the tetraploid cultivar (27–39%) than the diploid cultivars (35–l55%). Each cultivar had an optimum harvest time before which yield was affected by immature seeds and beyond which it was adversely affected by shedding of inflorescences and seeds and sprouting of seeds on the inflorescences. The optimum time to harvest Sabtoron was early September, Hungaropoly early to mid‐September and the late flowering cultivar S123 mid‐September when less than 4% of the inflorescences were still unripe. Seed yield and inflorescences per unit area were lower in the tetraploid cv, Hungaropoly (maximum 542 kg ha−1) than diploid cv. Sabtoron and S123 (864 and 897 kg ha−1 respectively) although the tetraptoid had heavier seeds. It is concluded that the optimum time to harvest red clover for seed production is about three or four weeks after the end of the period of rapid inflorescence production and that this coincides with the time when only a small proportion of unripe inflorescences remain.