bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of variety, cutting interval and nitrogen application on the morphology and development of stolons and leaves of white clover
Authors: WILMAN D. , ASIEGBU J. E.
Published: April 2006

Six varieties of white clover, each grown with perennial ryegrass, four intervals between cuts and two levels of applied nitrogen in all combinations, were compared in a field experiment during the first 27 months after sowing. Information about yields, crop fractions, heights and ryegrass tillers has been presented in an earlier paper (Wilman and Asiegbu, 1982). The present paper is concerned with the more detailed studies of white clover, which help to explain the yield results and contribute to the understanding of the response of this species to management when grown in competition with grass.

Increasing the interval between harvests increased the length of clover stolon per unit area of ground and increased stolon diameter, petiole length, weight per leaf and number of leaves harvested as a proportion of the number present in the sward while only slightly reducing the rate of leaf emergence, helping to explain the positive effect of increasing the interval on clover yield noted in the earlier paper. During regrowth, successive leaves had longer petioles and the length of individual petioles increased beyond the stage at which the leaflets were fully opened. Weight per leaf in clover increased considerably from April to June and declined to below the April value by October. It was shown that weight per leaf can be greatly increased by increasing the interval between harvests without reducing the number of leaves harvested per unit area per year. The stolon length measurements provided some support for the view that medium large‐leaved varieties of white clover can with advantage be defoliated rather less frequently than small‐leaved varieties. Stolon length was less adversely affected by applied N in the medium large‐ than in the small‐leaved varieties. The small‐leaved varieties had thinner stolons than the medium large‐leaved varieties but about twice the stolon length when no N was applied, and a relatively high proportion of leaves which escaped defoliation. The application of N reduced stolon diameter, increased petiole length and had little or no effect on weight per clover leaf.
The intake and feeding value for young beef cattle of two cultivars of tetraploid Italian ryegrass when grazed or conserved by artificial dehydration or ensilage
Authors: WILKINSON J. M. , LE DU Y. L. P. , COOK J. E. , BAKER R. D.
Published: April 2006

Two experiments were carried out to determine whether the differences in intake and feeding value previously shown between two grass cultivars when offered to ruminants as chopped artificially dehydrated (dried) material could also be demonstrated when the grasses were offered in other forms. Two cultivars of tetraploid Italian ryegrass (Lolium multiflorum), Sabalan and Tetila, were established in the same field in 1975. In 1976 they were grazed and conserved (two cuts of primary growth) as dried material or as silage.

The composition of the herbage selected at pasture and conserved showed higher concentrations of normal detergent fibre and acid detergent fibre in the dry matter for Tetila than for Sabalan, but differences between cultivars in digestibility were small. In both grazing and winter feeding trials differences in voluntary intake between the two cultivars were not significant, but at pasture young beef cattle spent less time grazing and tended to spend more time ruminating on Tetila than Sabalan. There was no measure of animal performance at pasture but liveweight gain was 15% higher for Sabalan than Tetila when both were offered to young beef cattle as the sole feed of dried grass or of silage. The voluntary intakes of the three forms of feed were very similar, which in part reflected a similarity in digestibility. However, gains were lower for calves given silage than those given dried grass. This may have been due to a lower efficiency in the utilization of the nitrogeneous components of silage for tissue growth than those of dried grass.
Effect of stage of maturity and chop length on the chemical composition and utilization of formic acid‐treated ryegrass and formic acid silage by sheep
Authors: ANDERSON R.
Published: April 2006

Two areas of an early‐heading perennial ryegrass cv. Cropper were harvested by either a precision‐chop or a flail harvester at around 50% ear emergence (15 May 1978) and 14d later (29 May). Formic acid (85%) was applied at the rate of 2·2 litres t‐1. Mature crossbred wethers were used in a 2 × 2 factorial design to determine the effect of stage of maturity and method of harvesting (chop length) on the in vivo digestibilities of formic acid‐treated grass in experiment 1 and formic acid silage in experiment 2. Apparent digestibility coefficients were determined at a fixed level of feeding for both grass and silage and at ad libitum access to feed for silage only.

There were no significant differences in the concentrations of crude protein (CP), ether extract (EE), acid‐detergent fibre (ADF) or acid‐detergent lignin (ADL) in grass or silages of differing chop lengths but the later cut forages had significantly higher ADF and ADL concentrations and lower CP concentrations than the early‐cut forages. The ADF and ADL concentrations were also higher in the silages than in the corresponding grasses.

In general, the fermentation characteristics of precision‐chopped silage were better than for the corresponding flail‐cut silage but date of harvest was a more important determinant of quality and the late, flail‐cut silage had the highest butyrate and ammonia N concentrations and the highest pH (411) of any treatment. There was a significantly higher intake of precision‐chopped as compared with flail‐cut silage with both the early‐and the late‐cut silage but there were no significant differences attributable to stage of maturity (i.e. date of harvest) or significant interaction between chop length and maturity. The slightly increased intake of early harvested, precision‐chopped silage as compared with late precision‐chopped silage was not significant.

Dry matter digestibility (DMD) of the grass decreased at a rate of 0004 units d‐1 post 50% ear emergence. The results of experiment 2 indicated a decrease of 0·207 units d‐1 in silage fed at a similar level. The late‐cut silage (DMD 0·292, mean of both harvesting treatments) thus had a significantly lower digestibility than the corresponding grass (mean DMD 0·247). Chop length had a variable influence on the DMD of both grass and silage fed at a fixed level but treatment differences were non‐significant. However, a trend towards higher digestibility of flail‐cut as compared with precision‐chopped silage was apparent and this became statistically significant when the animals were allowed ad libitum access to feed. This may be a response to the generally lower intake of flail‐cut silage.
Low‐cost pepsin‐cellulase assays for prediction of digestibility of herbage
Authors: CLARKE T. , FLINN P. C. , McGOWAN A. A.
Published: April 2006

Eight samples of perennial ryegrass‐white clover herbage with in vivo dry matter digestibility (DMD) ranging from 0·279 to 0·264 were used to evaluate various cost‐saving modifications to the two‐stage pepsin–cellulase digestibility technique. The effect of sample size, cellulase quality, cellulase/sample ratio, digestion time and washing of residue following digestion were investigated. The loss of dry matter (DM) in the assay was correlated with in vivo DMD and each variation of the method was evaluated by comparing the s.d. between replicates and r.s.d. of the regression, as well as the convenience of the method for large‐scale monitoring of digestibility of mixed ryegrass‐clover herbage.

It was found that the amount of cellulase used could be reduced by a factor of 25, compared with recently published methods, without increasing s.d. or r.s.d. appreciably. In addition stirring during digestion and washing of the residue could be omitted without any deleterious effects. Increasing digestion time did not reduce s.d. or r.s.d. and the low‐grade cellulase proved to be slightly more economical.

Increasing the sample size from 0·25 to 0·20 g improved the s.d. and r.s.d. but the residues from the larger samples were generally slower to filter, which made the assay unsuitable for routine use. Substantial reduction of digestion volume and use of a thermostatically controlled water bath instead of an incubator led to a considerable increase in efficiency and throughput of samples. Stirring the samples during digestion was found to be unnecessary, thus allowing more flexibility in the laboratory routine, for example using the weekend for digestion. Using the recommended method modification the repeatability between replicates and r.s.d. of the calibration regression was 0·204 and 0·215 respectively for samples ranging in DMD from 0·279 to 0·264.
The influence of the epidermis on the drying rate of red clover leaflets, leaf petioles and stems at low water contents
Authors: HARRIS C. E. , SHANMUGALINGAM V. S.
Published: April 2006

An apparatus is described which enables excised pieces of plant material lo be weighed al frequent intervals as they dry in controlled conditions of temperature, humidity and air‐speed. The effect of removing the epidermis on the drying rate of red clover (Trifolium pratense) leaflets, leaf petioles and stems is examined. Initially this treatment caused a very large increase in the drying rate of leaflets. Although the effect declined as water content fell, leaflets from which the epidermis had been removed still dried more rapidly than the controls at a water content equivalent to 50% of the dry weight. Removing the epidermis had a greater effect on the drying rate of leaf petioles and stems at low water contents than it did on the drying rate of leaflets.

Slow drying at low water contents is a major factor responsible for the undesirably long periods for which hay may lie in the field. Slow drying occurs even though swath microclimate becomes more favourable for drying as water content falls. The results presented here suggest that treatments which reduce cuticular resistance have the potential to reduce field drying time.
The rate of addition of formic acid to grass at ensilage and the subsequent digestion of the silage in the rumen and intestines of sheep
Authors: CHAMBERLAIN D. G. , THOMAS P. C. , WAIT M. K.
Published: April 2006

The main object of the experiment was to assess the effect of the relative proportion of non‐protein nitrogen (NPN) to total nitrogen in silage on digestion in the sheep. Four unwilted perennial ryegrass silages were made with the addition of formic acid at 0, 2·2, 4·2 and 5·2 litres t‐1 to provide foods with NPN proportions reducing from 0·26 to 0·20 of the total N. The digestion of the silages was studied in a 4 × 4 Latin Square experiment with sheep cannulated in the rumen, proximal duodenum and terminal ileum.

Results for organic matter (OM), cellulose and N showed no major difference between silages in their digestion in the rumen, small intestine and caecum and colon, though small differences (P <0·25) in rumen fermentation pattern and in the proportion of digestible OM disappearing in the small intestine were observed. Concentrations of ammonia N in the rumen and rates of rumen bacterial protein synthesis did not differ significantly between silages and there were no treatment effects on the passage of individual amino acids to the small intestine. The results indicate that the proportions of NPN to total N in the silages examined had little influence on the efficiency of silage N utilization in the rumen or on the passage of undegraded dietary protein to the small intestine.
Silage and milk production: comparisons between unwilted and wilted grass silages made with different additives
Authors: CASTLE M. E. , WATSON J. N.
Published: April 2006

Four grass silages, all made in mid‐July from second‐harvest perennial ryegrass swards, were compared in a 16‐week feeding experiment with twelve Ayrshire cows. Two silages were unwilted and two wilted. All the silages received formic acid (‘Add‐F’) at the rate of 3 litres t‐1 either with formalin at the rate of 1 litre t‐1 or without formalin. The unwilted and wilted silages had mean dry matter (DM) concentrations of 200 and 243 g kg‐1, and in vitro D‐values of 0·293 and 0·272 respectively. The silages were offered ad libitum plus 6 kg concentrates per cow per day. The daily intakes of unwilted and wilted silage DM were 10·2 and 9·2 kg per cow respectively on the formic acid treatment, and 10·2 and 9·2 kg on the formic acid + formalin treatment. The mean daily milk yield on the unwilted silage treatments was 19·2 kg per cow which was significantly higher than the yield of 17·2 kg per cow on the wilted silage treatments. The formalin had no significant effect on milk yield. The four silage treatments had small and non‐significant effects on milk composition. It is concluded that the unwilted silages, which had excellent fermentation characteristics, were superior to the wilted silages as a feed for dairy cows.
The productivity of grassland farms in seven climatic zones of England and Wales
Authors: PEEL S. , MATKIN ELIZABETH A.
Published: April 2006

Records of grassland productivity were kept for 2 years on 152 dairy and 179 beef farms. Results were collated for six lowland zones, delineated primarily on the basis of average rainfall, and an upland zone. Contemporary and long‐term average meteorological records were also collected.

In most of the lowland zones stocking rates and use of fertilizer N were similar, but utilized metabolizable energy (UME) output from grass varied; it was 25% higher in the wet, cool zone of north‐west England and east Wales than in the dry zone of eastern England. The ranking of zones for utilized output corresponded closely with the ranking for summer rainfall.

On upland farms stocking rate was 25% lower and UME output 15% lower than on lowland farms, but this was achieved from little more than half the N input.

The differences between zones were similar to those shown in other published farm data. They also showed a similar trend to that demonstrated in grass cutting experiments. This suggests that farmers were, on average, able to exploit the extra grass grown in wetter climates. The incidence of difficult topography and impeded drainage was similar in dry and wet zones, but did have a more serious effect in the wet zones. The much higher level of concentrate feeding in the driest zone may have reduced the utilization of grass.
Soil acidification induced by leguminous crops
Authors: HAYNES R. J.
Published: April 2006

Solution culture and greenhouse studies have both clearly demonstrated the ability of legumes to acidify their rooting medium. Furthermore, research workers comparing the pH beneath undisturbed sites versus all‐legume pastures or all‐grass versus all‐legume (or grass‐legume) pastures have observed a lower soil pH under the leguminous pastures. The processes leading to legume‐induced soil acidification are reviewed and discussed.

The growth of legumes which are fixing atmospheric N2 involves the excess uptake of nutrient cations over anions from soil solution. This results in the net efflux of H3O+ ions from plant roots into the rhizosphere.

When virgin lands are sown with legumes the accumulation of soil organic matter, with a consequent increase in cation exchange capacity and exchange acidity, is an important contributing factor to the long‐term decline in surface soil (0–10 cm) pH. Nonetheless, such a phenomenon does not explain the decrease in pH below 10 cm soil depth nor the lower pH below leguminous than all‐grass pastures. The efflux of H3O+ ions from the legume roots may have an important effect on the soil pH under such conditions. The loss of symbiotically fixed N; from the system through leaching of NO3− ‐ N may also contribute to soil acidification under leguminous pastures.
The response of white clover to different strains of Rhizobium trifolii in hill land reseeding
Authors: YOUNG N. R. , MYTTON L. R.
Published: April 2006

S184 and Grasslands Huia white clover were surface seeded into native Molinia pasture on a wet stagnogley hill soil containing no indigenous Rhizobium trifolii. Seedlings were ‘spray inoculated’ after emergence with each of five strains of R. trifolii. The two best rhizobial treatments produced a sevenfold increase in seedling establishment followed by nearly fivefold improvement in dry matter production in the following year. There was a strong interaction between Rhizobium strains and plant varieties. Results re‐affirm the potential for improving clover performance through inoculation and also demonstrate the need for a better understanding of the factors leading to establishment of successful plant‐Rhizobium associations before predictable performance can be achieved in these harsh hill environments.
Pre‐harvest desiccation of crops for conservation
Authors: TETLOW R. M.
Published: April 2006

Two experiments were conducted to determine the effect of pre‐harvest treatment by formic acid spray on the moisture concentration (MC) of perennial ryegrass (Lolium perenne) in vegetative growth. In Experiment 1 aqueous solutions containing 0.080, 0.148 and 0.259 kg formic acid per litre were applied to a perennial ryegrass sward (fresh matter yield 21.0 t ha−1) at a constant volume of 41.2 litres t−1to give active ingredient application rates of 3.5, 6.0 and 11.5 kg t−1 respectively. In Experiment 2 similar solutions were applied to a perennial ryegrass sward (fresh matter yield of 6.9 t ha−1) at 35.2, 19.0 and 10.9 litres t−1 respectively to give a constant formic acid application of 2.8 kg t−1. The changes in MC and chemical composition after treatment with acid were compared with those in untreated plots

In both experiments treatment with acid significantly reduced the MC (P < 0.001) within 5 h of treatment from 4.4 to 3.0 kg per kg of dry matter (DM) in Experiment 1 and from 3.0 to 2.6 kg per kg DM in Experiment 2. There was no effect of level of acid applied in Experiment 1 or of the volume of water applied with the low level of acid in Experiment 2 on the changes in MC of acid‐treated plots. There was however a significant (P < 0.00l) difference between the MC of plots treated with acid and those untreated which was maintained in Experiment I for up to 9 d even during rainfall.

There were no differences between the chemical compositions of samples from acid‐treated plots in either Experiment I or 2 or between untreated and acid‐treated plots in Experiment 2. However there were significant differences between untreated and acid‐treated plots in Experiment 1 for the content of nitrogen (N), water‐soluble carbohydrate (WSC) and digestible organic matter (DOM). There were changes in the content of N, WSC and DOM with time in both experiments. In Experiment I there was an interaction between sampling time and treatment for both N and WSC but not for DOM. Compared with untreated plots, treatment with acid at all levels accelerated the loss of WSC and delayed the fall in N content. There were no such interactions in Experiment 2.
Influence of stage of maturity on the nutritive value of Italian ryegrasses
Authors: HIDES D. H. , LOVATT J. A. , HAYWARD MARGARET V.
Published: April 2006

The influence of harvesting date on the nutritive value of the Italian ryegrass cv. RvP from Belgium and of Bb 1277, an introduced ecotype from the Po valley, was investigated.

Ten clonally replicated genotypes of each population were grown as closely spaced plants and two ramets of each genotype harvested every 4 d for a period of 28 d after inflorescence emergence. Dry matter digestibility (DMD) was estimated and fibrosity index (FI) determined on both the leaf and stem fractions, and cellulose and lignin concentrations were determined on the stem fractions.

The nutritive value of the leaf in terms of both DMD and FI which was the same for both cv. RvP and Bb 1277 throughout the period of harvesting, was always higher and declined at a slower rate with increasing maturity than that of the stem. The stem of Bb 1277 declined in DMD and increased in FI and cellulose concentration at a significantly slower rate than cv. RvP. Significantly higher levels of DMD were detected in the stem of Bb 1277 for harvests 5 to 8 and significantly lower levels of FI and cellulose concentration from harvests 4 to 8. It was not, however, possible to detect any significant differences in stem lignin concentration. Dry matter yields increased throughout the period of harvesting and there were no significant differences between cv. RvP and Bb 1277.

The results are discussed in relation to the breeding potential of the high nutritive value of the Po valley ecotype Bb 1277 and the use of the DMD and FI determinations for selecting for improved herbage quality in Italian ryegrass.
Influence of temperature on the digestibility of the tropical legume Macroptilium atropurpureum
Authors: WILSON J. R. , MINSON D. J.
Published: April 2006

The effect of temperature on the nutritive value of Macroptilium atropurpureum cv. Siratro and line 10–105 was determined in a controlled environment at day/night temperatures of 24/18, 30/24 and 36/30°C, and a 13‐h daylength. Estimated dry matter digestibility, cell wall and lignin concentrations of leaf, stem and stubble were measured in two 5‐week regrowth cuts.

Siratro and line 10–105 were similar in digestibility and responded similarly to temperature with whole tops, stem and stubble decreasing by an average of 0.0023, 0.0026 and 0.0056 units of digestibility for each 1°C rise in growth temperature. These changes reflect the increase in cell wall and lignin concentrations with higher temperature.

The digestibility of young, just‐expanded leaves was increased by increased growth temperature. This effect may be explained by the faster rate of leaf expansion at high temperature which reduced cell wall and lignin concentrations at this stage of leaf development. However, for the bulk leaf fraction digestibility was unaffected by temperature. Leafiness declined at high temperatures.
Effect of stocking rate on the grazing behaviour and faecal output of lactating dairy cows
Authors: STOCKDALE C. R. , KING K. R.
Published: April 2006

Information about the grazing behaviour and the return of dung to pasture by lactating dairy cows was collected from stocking rate experiments in northern Victoria. Grazing behaviour was observed for 24‐h periods in mid‐summer in two years. Grazing time increased as herbage allowance decreased to about 32 kg DM cow−1 d−1 but as herbage allowance decreased further grazing time also decreased. A herbage allowance of 32 kg DM cow−1 d−1 corresponded to a stocking rate of about 5.5 cows ha−1. This effect of herbage allowance on grazing time may have been confounded by herbage mass, however. Rumination time of the cows increased by 003 h for each kg increase in herbage allowance while resting time was not affected by treatment.

The effects of stocking rate on some of the characteristics of faecal output were measured for a 3‐d period in mid‐summer. The number of pats deposited per cow daily declined by 0.66 for each unit increase in stocking rate. The fresh weight of dung also declined as stocking rate increased by 0.16 kg per unit of stocking rate. While the values for the amounts of dung deposited on the pasture by the cows at the lower stocking rates are similar to many of those reported in the literature, this study has quantified the way in which stocking rate may influence this in one instance. Furthermore, provided that some measure of herbage intake is made when measurements of dung excretion are performed, it is suggested that estimates of in vivo digestibility can be obtained.
Seasonal distribution of stem‐boring larvae including frit fly (Diptera: Oscinella frit L.) and pest damage in perennial ryegrass
Authors: CLEMENTS R. O. , CHAPMAN P. F. , HENDERSON I. F.
Published: April 2006

Changes in the population of stem‐boring Dipterous larvae (including Oscinella frit) were examined weekly for a year on plots of perennial ryegrass (Lolium perenne cv. S24). The herbage net regrowth rate of these plots and of plots receiving the pesticide, phorate, was also monitored. Herbage net regrowth rates were greatest in April and October. At the same times the differences in net regrowth between treated and untreated plots were greatest, thus indicating the periods of the greatest loss of production due to pest damage to the sward.

Populations of stem‐boring larvae fell below 100 m−2 for only 4 weeks in the year and were maximal in autumn and early winter. Larval mortality exceeded 50% during the winter period. A correlation was found between larval activity and sward damage.
The release of mineral elements from grass silages incubated in sacco in the rumens of Jersey cattle
Authors: ROOKE J. A. , AKINSOYINU A. O. , ARMSTRONG D. G.
Published: April 2006

The objective of the study was to determine the rate and extent to which calcium (Ca), copper (Cu), magnesium (Mg), potassium (K), phosphorus (P), sodium (Na) and zinc (Zn) were released from polyester bags containing grass silages incubated in the rumens of cattle. The rate of mineral disappearance from the bags was faster than the rate of dry matter disappearance. The disappearance of each mineral element from the bags was characterized by a rapid release of the mineral within 2 h of placing the bags in the rumen followed by a slower release extending up to 48 h of rumen incubation. The extent to which each mineral was rapidly released from the silages differed significantly and the minerals were ranked in the order P < Zn < Ca < Cu < K < Mg < Na. There were no differences between minerals in the rate at which they were released during the slower phase.

Combination of these results with different rates of outflow of material from the rumen showed that for each of the minerals examined more than 0.65, on a proportional basis, was released from the silages; for Na the values were greater than 0.90. Indeed, all the residual Na and P remaining in the bags after 48 h rumen incubation could have resulted from bacterial
Variability of the in vitro digestibility of standard herbage samples
Authors: DHANOA M. S. , DERIAZ R. E.
Published: April 2006

The results or estimations of in vitro digestibility of three standard herbage samples, analysed weekly over about 48 weeks per year, have been examined using time‐series methods of Box and Jenkins to separate seasonal and non‐seasonal trends. The study includes data from March 1971 to February 1981. The dominant feature of variability is the seasonal component with a cycle of 52 weeks; no other significant cycles of longer periods were detected. The model of Box and Jenkins (1976) was found to be the most appropriate in describing the three series. A decrease in the in vitro digestibility of the low standard, which is 10 years old, occurred over the last year or so, although the reasons for this apparent storage effect are unknown.
Sward composition and output on grassland farms
Authors: PEEL S. , GREEN J. O.
Published: April 2006

Records of grassland productivity were kept for 2 years on 136 lowland dairy farms and 131 lowland beef farms. The grassland on each farm was classified according to the proportion of sown (preferred) species. The farms were then ranked on this basis and divided into quarters:

On dairy farms the lowest quarter had 31% sown species and utilized metabolizable energy (UME) output from grass of 40.8 GJ ha−1, whereas the highest quarter had 70% sown species and UME output of 45.6 GJ ha−1. Dairy farmers in the lowest quarter used least fertilizer N and differences in output were no greater than would be expected from differences in N input. On beef farms the lowest quarter had 28% sown species and UME output of 32.3 GJ ha−1, and the highest quarter had 63% sown species and UME output of 45.9 GJ ha−1On these farms differences in fertilizer N could not completely account for differences in output.

It is concluded that on beef farms botanical composition of grassland is a good indicator of its productivity but is not necessarily a prime cause of differences in output. On dairy farms there is little evidence of a direct benefit resulting from a high proportion of sown species. On such farms the need for deliberate manipulation of the botanical composition of grassland by reseeding or chemical means is questioned.
The effect of stocking rate and fertilizer usage on income variability for dairy farms in England and Wales
Authors: DOYLE C. J. , LAZENBY A.
Published: April 2006

A mathematical model of grass production and utilization on a dairy farm is described. Using the model an assessment has been made of the extent to which financial uncertainty arising from year‐to‐year variability in grass yields, coupled with a preference among farmers for minimizing risks, may explain the relatively low stocking rates and observed nitrogen usages on many dairy farms in England and Wales. The degree of risk has been equated with the probability of profits in a particular year being less than those required to cover the consumption needs and short‐term borrowing requirements of the farmer. The results of the analysis indicate that a strategy of minimizing risks may lead to a significantly lower stocking rate than one of maximizing profits. Thus, considerations of risk may lead to stocking rates which are suboptimal from the viewpoint of economic and biological efficiency. However, there is no evidence to suggest that the comparatively low average usage of nitrogen on dairy farms in the UK is determined by risk considerations. On the contrary, increasing nitrogen usage lowers the apparent financial risk at a given stocking rate.
The drying rates of component parts of inflorescence‐bearing tillers of Italian ryegrass
Authors: HARRIS C. E. , DHANOA M. S.
Published: April 2006

Inflorescence‐bearing tillers of Italian ryegrass (Lolium multiflorum cv. RvP) were dried in controlled temperature, relative humidity and air speed conditions chosen to be within the range likely to occur in a hay swath drying in the field. After drying for increasing intervals the tillers were separated into inflorescence, exposed flowering stem, leaf‐laminae, leaf‐sheath and flowering stem enclosed by leaf‐sheath and the drying rates of these components in addition to that of whole tillers were measured. There were large differences in drying rate between components, but the differences were similar over the range of drying conditions employed. The drying rate of the inflorescence as well as that of stem enclosed by leaf‐sheath was found to be very low and that of leaf‐laminae and leaf‐sheath very high.
The ingress of Poa annua into perennial ryegrass swards
Authors: WELLS G. J. , HAGGAR R. J.
Published: April 2006

The ingress of Poa annua into established swards of perennial ryegrass was recorded in four experiments aimed at determining whether ingress was due to P. annua aggression or to a decrease in ryegrass vigour. Emphasis was placed on severity of defoliation, effect of bare spaces and the time of year most favourable to colonization.

In Experiment 1, P. annua ingress was greatest in the autumn, especially where ryegrass had been sown in rows rather than broadcast sown. In Experiment 2, seedlings of P. annua only established successfully in mature ryegrass swards that had been defoliated at intervals of two weeks. Experiment 3 showed that ingress was inversely related to the vigour of the ryegrass cultivar, being particularly high on frequently defoliated plots. In Experiment 4, which involved a study of the colonization of poached areas, more seedlings established in quadrats surrounded by P. annua‐dominant pasture compared with patches surrounded by perennial ryegrass.

It is concluded that P. annua is not an aggressive species; it colonizes only open ryegrass swards that have become weakened by intensive management.
Some effects of fertilizer and frequency of defoliation on the botanical composition and yield of permanent grassland
Authors: WILLIAMS E. D.
Published: April 2006

Small plots of permanent pasture containing 50%Agrostis capillaris‐Festuca rubra were defoliated frequently or infrequently during the growing seasons in 1978–80 and fertilized with 133, 125 and 125 kg N, P2O5 and K2O respectively ha−1 a −1 or not fertilized during 1978–81. Yields of herbage were assessed during 1979–80 and botanical composition assessed on three occasions in 1978, once in April 1979 and once in 1982.

Fertilizer application increased annual dry matter (DM) harvested from frequently cut plots by 40%, 53% and 65% in 1978, 1979 and 1980 respectively, and on infrequently cut plots it doubled hay DM harvested in 1978 and increased total DM harvested by 126% and 186% in 1979 and 1980 respectively. Infrequent cutting and fertilizer both decreased the proportion of A. capillaris but only fertilizer decreased the proportion of F. rubra. Fertilizer greatly increased the proportion of Holcus lanatus especially where plots had been cut frequently and of Alopecurus pratensis where they had been cut infrequently. It decreased the proportion of Luzula campestris. Infrequent cutting, especially with fertilizer, discouraged Cerastium fontanum ssp. glabrescens and Trifolium repens but encouraged Rumex acetosa.
A comparison of a rising‐plate meter and an electronic capacitance meter for estimating the yield of pastures grazed by dairy cows
Authors: STOCKDALE C. R. , KELLY K. B.
Published: April 2006

The performances of a rising‐plate meter and a single‐probe electronic capacitance meter were compared for estimating the herbage mass of irrigated pastures both before and after grazing by dairy cows. Mean CV for the rising plate meter and the single‐probe meter were 12.7% and 13.3% respectively when herbage mass was measured before grazing, and 21.8% and 15.4% respectively immediately after grazing. These coefficients of variation indicate that while the performance of the two meters was similar when herbage mass was measured before grazing, the single‐probe meter was a more precise instrument for estimating herbage mass after grazing.

Trampling of herbage prior to measurement had a major effect on the regressions of both meters; the regression intercept was increased by 2800 kg dry matter (DM) ha−1 for the rising‐plate meter and by 2580 kg DM ha−1 for the single‐probe meter. The slopes of the graphs, however, remained unchanged.

It was concluded that while the single‐probe meter performed better than the rising‐plate meter for estimating the mass of post‐grazing herbage when trampling was negligible, the large effect that trampling had on the post‐grazing calibration regressions precluded both instruments from general use in dairy cattle research. This indicates that another technique is required in circumstances in which pastures are heavily trampled.
Establishment of legumes in grass swards: effects of pesticides on slugs, insects, legume seedling numbers and forage yield and quality*
Authors: BYERS R. A. , TEMPLETON W. C. , MANGAN R. L. , BIERLEIN D. L. , CAMPBELL W. F. , DONLEY H. J.
Published: April 2006

Three legumes, red clover (Trifolium pratense L.), alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.), were planted with a minimum‐tillage drill into eight grass fields, three in early spring, two in late spring and three in late summer, in Pennsylvania. The objective was to use pesticides at planting time to control slugs and insects which attack legume seedlings and ascertain whether pest control prevented seedling loss and increased yields of grass and legume dry matter (DM), in vitro DM digestibility and crude protein (CP). Methiocarb bait alone or in combination with carbofuran granules or spray applied at planting sometimes controlled the slugs Derocerus reticulatum (Müller), D. laeve (Müller) and Arion fasciatus Nilsson and improved establishment of seedling red clover and alfalfa but not birdsfoot trefoil. Increased yields of DM, digestible DM, CP and legume DM after treatment was greatest in late‐spring sowings. Larvae of the clover root curculio, Sitona hispidulus (F.), attacked roots of legumes in the spring following the year of sowing. Late spring and summer sowings without pesticides sustained considerable seedling losses from pests, whereas seedlings from early spring sowings in untreated areas were injured less.
Canopy structure and productivity of Festuca avundinacea Schreb. swards during vegetative and reproductive growth
Authors: SUGIYAMA S. , YONEYAMA M. , TAKAHASHI N. , GOTOH K.
Published: April 2006

Canopy structure, productivity and their relationships were examined in 2‐year‐old swards of fourteen tall fescue (Festuca arundinacea Schreb.) strains during the vegetative and reproductive growth stages. During the vegetative growth stage morphological characters, particularly tiller size, were closely associated with productivity. Swards with large tillers showed an effective distribution of the incoming light energy within the canopy and hence low extinction coefficient (K) value and high productivity at complete light interception. On the other hand, although there was no apparent correlation between K and the productivity or the whole crop during the reproductive growth stage, the productivities of the reproductive and vegetative tillers were positively and negatively related to K respectively. Leaf area index of the reproductive tillers and their position in the canopy had marked effects on the distribution of the incoming light energy within the canopy and on the productivity of both types of tillers. The productivity of the vegetative and the reproductive tillers is discussed in terms of the effect of the competition for incoming light energy between both types of tillers.
Silage and milk production: studies with molasses and formic acid as additives for grass silage
Authors: CASTLE M. E. , WATSON J. N.
Published: April 2006

In two separate feeding experiments using a total of twenty‐four individually housed Ayrshire cows six silages made from perennial ryegrass were offered ad libitum with supplements of concentrates. In Experiment I herbage with a dry matter (DM) concentration of 225 g kg−1 received either formic acid (‘Add‐F’) at the rate of 2·0 litres t−1 or undiluted cane molasses at rates of 10, 20 and 30 litres t−l; the mean daily silage intakes were 9·54, 908, 9·27 and 9·49 kg DM per cow and the daily milk yields, corrected to 40 g fat kg−1, were 23·2, 22·3, 22·8 and 22·9 kg per cow respectively but none of the differences between the four treatments was significant. In Experiment 2 herbage with a DM concentration of 269 g kg−1 received formic acid at a uniform rate of 2·6 litres t−1 either with or without an additional application of molasses at 20 litres t−1; the mean daily silage DM intakes were 8·70 and 9·28 kg per cow and the daily fat‐corrected milk yields were 22·2 and 21·9 kg per cow respectively and were not significantly different. In both experiments the effects of the treatments on milk composition were small and not significant. It is concluded that there were no advantages in applying molasses to herbage treated with formic acid, and that the rate of application of molasses to untreated herbage which equated with the formic acid application was 20·30 litres t−l when assessed on the basis of silage composition, intake and milk production.
Unwilted and prewilted grass silage for finishing bulls*
Authors: COTTYN B. G. , BOUCQUE V. , FIEMS L. O. , VANACKER J. M. , BUYSSE F.X.
Published: April 2006

Three silages were prepared from perennial ryegrass; unwilted without additive (UW), unwilted treated with 3·5 litres commercial (85%) formic acid (UWA) and prewilted without additive (WN) with dry matter (DM) concentrations of 189, 209 and 328 g kg−1 respectively. The three silages were offered ad libitum in a 348‐d feeding experiment to three groups of eight Belgian white‐blue bulls with an initial live weight (LW) of 277 kg. The concentrate (47 g digestible crude protein (CP) kg−1) supplementation was 7·5 g (kg LW)−1. Acid treatment (UWA) slightly improved digestibility of all silage nutrients except CP, whereas wilting generally slightly decreased digestibility of the nutrients except DM and ether extract. The daily LW gain averaged 912 g and was not significantly different on the three different treatments. DM intake per (kg LW)0.75 was higher with the UWA silage, 69·3 g, and with the WN silage, 71·6 g, than with the UW silage, 65·8 g. However, this difference in DM intake was not reflected in either daily LW or carcase gain. The DM of UW silage was more efficiently utilized than DM of UWA or WN silage.
The effects of stocking rate and nitrogen fertilizer on a perennial ryegrass‐white clover sward
Authors: CURLL M. L. , WILKINS R. J. , SNAYDON R. W. , SHANMUGALINGAM V. S.
Published: April 2006

The effects of stocking rate and N fertilizer on a mixed sward of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) set‐stocked with sheep were examined. Sward production and composition, and sheep production were studied.

Increasing the stocking rate over the range 25–55 yearling sheep ha−1 reduced herbage accumulation by about 40%, whether or not N fertilizer was applied. Increasing the stocking rate increased the density of ryegrass tillers, but reduced the density of clover stolons and the clover content of the swards. Applications of N fertilizer (200 kg N ha−1 a−1) increased herbage accumulation by about 20% but substantially reduced the clover content.

Liveweight gain per animal and per unit area were greater at the lower stocking rates where the clover content and nutritive value of the diet were greatest. Wool growth per unit area was greater at the higher stocking rates. Applications of 1M fertilizer increased liveweight gain at stocking rates above 25 sheep ha−1, but had no effect on wool production at any stocking rate.

The results demonstrate that a stable and productive grass‐clover association was maintained under conditions of set‐stocking at around 23 yearling sheep ha−1and that at this stocking rate, which appears to be about the biological optimum, there was no advantage in using N fertilizer.
The effect of nitrogenous fertilizer on the photosynthesis of leaves of a ryegrass sward
Authors: WOLEDGE JANE , PEARSE P. JOY
Published: April 2006

The addition of nitrogenous fertilizer to a newly cut, N‐deficient ryegrass sward resulted in an increased photosynthetic capacity in the next leaf to expand, showing that greater photosynthesis per unit leaf area as well as greater leaf area contributes to the increased growth of fertilized swards. Later in the 4‐week growth period there was little difference in photosynthetic capacity between fertilized and unfertilized swards.
Resistances of grasses to two sobemoviruses, cocksfoot mottle and cynosurus mottle
Authors: CATHERALL P. L.
Published: April 2006

Infection of Dactyls glomerata with cocksfoot mottle virus (Cf MV) and of Cynosurus cristatus with cynosurus mottle virus (CyMV) is frequently lethal. However, varieties of each species differ in the proportion of genotypes which survive, and in the damage suffered by these surviving plains. Infected plants of the CfMV‐resistant cocksfoot, cv. Cambria, were generally much more aggressive in the competitive environment of the sward than were infected plants of the susceptible cv. S37. Thus, Cambria populations outyielded comparable populations of S37 by only 7% when healthy, but by 40% when infected with CfMV. A few genotypes in the infected Cambria population apparently recovered from the disease, became virus‐free and were immune to further infection Resistance to CyMV in C. cristatus takes the form of resistance to systemic spread. A few symptomless and apparently virus‐free tillers grow up from the bases of infected tillers. However, these tillers are susceptible to further infection. It is suggested that, in resistant genotypes, CfMV and CyMV trigger the production of antiviral agent(s) which block or restrict virus replication. There is some evidence that CfMV resistance is virus isolate specific, and this could present problems when breeding for durable resistance.
Effect of after‐treatments on sward composition and the establishment of introduced species following the control of bracken
Authors: SPARKE C. J.
Published: April 2006

After bracken control with asulam the surface litter was removed by raking, burning or incorporation, or left in situ as a control. The proportion of grasses in the sward and the grass net herbage production was not significantly different on the four litter treatments 1 or 2 years after spraying.

Lime, phosphate and seed of Trifolium repens, Lolium perenne and Festuca rubra were applied to a similar set of four litter treatments. T. repens failed to establish in quantity on any treatment. A long period of dry weather following sowing may have been the initial reason, with competition from the established, more vigorous grasses subsequently being of importance. The sown grasses established most successfully where competition from the existing indigenous species had been removed by burning or incorporation of the litter and surface vegetation. Although these two treatments differed little in the proportion of sown grasses in the sward in the second season, the net herbage production of Lolium and Festuca was significantly higher on the incorporated than the burnt treatment. Net herbage production of these two grasses in the second season was significantly higher on the incorporated and the burnt treatments than it was on the control. After 2 years, total grass net herbage production was significantly greater on these two treatments than on the unfertilized, unlimed and unseeded control.
Manurial value of septic‐tank sludge on grassland
Authors: CARLTON‐SMITH C. H. , COKER E. G.
Published: April 2006

About 5% of the UK population is served by septic tanks and cesspits. In some districts this is applied to farmland. The Water Research Centre and South‐West Water collaborated in establishing a field trial to provide knowledge of the manurial value of septic‐tank sludge. The trial was designed to investigate the value of nitrogen (N), phosphorus (P) and potassium (K) contained in the sludge and applied over a 3‐year period to grassland. The approximate proportions of total nutrients present in the sludge applied which became available to ryegrass as inorganic fertilizer nutrients were:

Barley grown in the fourth year when no sludge was applied showed a significant response to residual sludge N and P remaining in the soil. It is concluded that septic‐tank sludge can supply useful amounts of N and P, and, unlike other forms of sewage sludge, significant quantities of K to grassland. Estimates of the nutrient value should be based on analysis for dry solids, and total N, P and K. Septic‐tank sludge is usually low in metal content and no metal contamination problems should arise when it is applied to land.
Effects of improved nutrition during lactation on the performance of hill lambs
Authors: O'TOOLE M. A.
Published: April 2006

Two experiments compared the effects of grazing by hill ewes with single lambs on lowland pasture for varying periods of time. In Experiment 1 lambs kept with their mothers on lowland pasture for 0, 21, 42 or 70 d before being moved to hill grazing gave daily liveweight gains (g) of 243,329, 338 and 348 respectively in the 1–21 days postpartum period; 243,248,310 and 314 in the 22–42 days period; 118, 132, 157 and 229 in the 43–70 days period and 105, 100, 115 and 98 in the 71 days to weaning period. In Experiment 2, ewes with single lambs grazed lowland pasture for 0, 21, 56 and 110 days and the daily liveweight gains (g) recorded were 233, 348, 343 and 353 respectively in the 1–21 days postpartum period; 184, 229, 306 and 297 in the 22‐56 days period and 109, 115, 141 and 209 in the 57‐110 days period. At each weighing up to weaning there was a positive correlation between lamb weight and the number of days spent on lowland pasture. Carcass weight and killing out percentages were each also significantly improved. The implications of these results in developing a hill‐sheep system are discussed.