bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors influencing seed movement and dormancy in grass seeds
Authors: SCHÖNFELD M. A. , CHANCELLOR R. J.
Published: April 2006

Awned seeds of four grasses were submitted to humidity changes on dry and damp soil to see how far the awns assisted in distribution and seed burial. The results indicate that awns on their own are probably of limited importance. In another study, seeds of seven species were soaked in water with high or low oxygen levels to determine whether dormancy could be induced. Waterlogging delayed germination briefly but did not induce dormancy except in Avena fatua. Oxygen level proved unimportant. The effect of temperature on germination and dormancy was examined in seeds of Agrostis capillars. Seeds of this species germinated best at fluctuating temperatures with a minimum difference of 10°C between day and night temperatures. Constant or slightly fluctuating temperatures over 20°C or under 10°C induced dormancy in a small percentage of seeds.
An economic assessment of the potential benefits of replacing grass by grass‐clover mixtures for 18‐month beef systems
Authors: DOYLE C. J. , MORRISON J.
Published: April 2006

A mathematical model which simulates the potential production and utilization of herbage on perennial ryegrass and grass‐white clover swards in the context of an 18‐month beef enterprise is described. Using the model the potential costs and benefits of replacing grass by grass‐clover mixtures have been determined. Potentially grass‐clover swards receiving no fertilizer N are shown to have annual DM yields equivalent to ryegrass swards receiving at least 300 kg N ha −1. Apart from the benefits of reduced fertilizer N usage there appear to be indirect benefits related to a lower concentrate requirement per head. In consequence, from an economic viewpoint grass‐clover swards potentially compare very favourably with heavily fertilized grass swards, even if account is taken of the opportunity costs of lower stocking rates associated with grass‐clover systems. However, this conclusion awaits experimental confirmation.
The productivity of May‐lambing ewes grazed at three stocking rates on lowland grass
Authors: NEWTON J. E. , BETTS J. E. , WILDE R. M.
Published: April 2006

For the 2 years 1977 and 1978 Masham ewes grazed a perennial ryegrass (Lolium perenne cv. S24) pasture from the beginning of April until the end of September each year. Twelve ewes were allocated to each of the three stocking rate treatments, 12 (L), 16 (M) and 20 (H) ewes per ha. Each treatment was rotationally grazed around six paddocks with a forward creep for the lambs. Conservation cuts were taken from each treatment in late May and were generally sufficient to cover a 3‐month winter feeding period for treatments L and M but were always insufficient for treatment H. Lambing took place at pasture during the second half of May. No concentrates were fed to the ewes during late pregnancy or lactation but lamb birth weights (4–8 kg) and lamb growth rates over the first 4 weeks (240 g d−l) were satisfactory. Organic matter intakes (OMI)of grass by the pregnant ewes(1816,1844 g OMI ewe−1) were not affected by the stocking rate. Intake of grass by the lactating ewes was affected by year and by stocking rate. The overall growth rate of lambs was higher on treatment L than either M or H but decreased on all treatments during the latter half of the grazing season, resulting in 43% of L and only 3% of M and H lambs being fit for slaughter by the end of September. The main features of this time of lambing are low costs and the production of predominantly store lambs.
The digestion by cattle of grass silages made with no additive or with the application of formic acid or formic acid and formaldehyde
Authors: ROOKE J. A. , GREIFE H. A. , ARMSTRONG D. G.
Published: April 2006

The aim of the experiment was to assess the effect of applying, at commercially recommended rates, formic acid or formic acid/formaldehyde at ensilage upon the subsequent digestion of the silages by cattle. Three wilted grass silages were made from perennial ryegrass ensiled at a DM concentration of 206 g kg−1 after a poor wilting period of 49 h without additive application and with application of 2.5 litres t−1 of formic acid or of 4.5 litres t−1 of a mixture of (gkg−1) 500 formic acid, 200 sulphuric acid and 200 formatin giving an application rate of 15 g formaldehyde kg−1 herbage crude protein (N × 6.25).

The silages were fed to cattle equipped with rumen cannulae and duodenal re‐entrant cannulae. Results from analyses of silage composition and from the digestion of organic matter and N showed no major differences between silages. The efficiency of rumen microbial N synthesis, the rumen degradability of silage N (determined in vivo or in sacco) and in vivo digestion of individual amino acids were also unaffected by additive treatment. These results indicate that poor wilting conditions before ensilage restricted the effectiveness of additive treatment; the ineffectiveness of formaldehyde in reducing the rumen degradability of silage N may also have been related to the low rate of formaldehyde application.
Grazing by sheep and the distribution of species through the canopy of a red clover‐perennial ryegrass sward
Authors: LAIDLAW A. S.
Published: April 2006

A trial was carried out to investigate whether or not sheep grazing at stocking rates of 22 (low) and 44 (high) ha−1 select red clover from a red clover‐perennial ryegrass sward, The distribution of botanical and morphological components was assessed in consecutive 5‐cm layers through the canopy inside and outside exclosure cages moved every 2 weeks for 6 weeks. The difference between inside and outside cages for a given layer was an indication of the amount of each component consumed from that position in the sward, and the corresponding difference for clover content was considered an indication of selection.

Evidence of selection was observed over the third and fourth weeks of grazing, especially in the high stocking rate treatment. Laminae of red clover were selected in preference to other plant parts and were grazed throughout the depth of the canopy in contrast to grass. The basal layer at the high stocking rate during weeks 5 and 6 was not grazed suggesting that the crown of red clover may be protected from severe overgrazing by accumulation of dead matter.

It was concluded that the low herbage density of red clover‐grass swards allowed the occurrence of selection which was most pronounced when the sward was being grazed down relatively quickly.
Photosynthetic rate and carbon balance of grazed ryegrass pastures
Authors: KING J. , SIM E. M. , GRANT S. A.
Published: April 2006

The relationship between net canopy photosynthesis (Pnc) measured at 400 J m−2 s‐1 and leaf area index (LAI) was determined on ryegrass‐dominant swards over a range of her bage masses in five grazing experiments. In three experiments the swards were continuously stocked either by sheep or by cattle to maintain a number of herbage heights and hence LAI values. In two experiments the swards were intermittently grazed with 21 ‐d regrowth intervals. On the continuously stocked swards measurements were made over nine periods each of 7 to 21 d in length. On the intermittently grazed swards measurements were made over six periods while the herbage was being grazed down from a high to a low LAI and over three periods during the regrowth phase.

On all the swards where measurements were made while grazing was in progress, the relation of Pnc to LAI was linear. The photosynthetic rate was greater on the continuously grazed than on the intermittently grazed swards up to LAI 35 and in two experiments to LAI 5. The relationship of Pnc to LAI of swards in the regrowth phase was predominantly curvilinear and such that over much of the LAI range they had a greater photosynthetic potential than the same swards being grazed down from high to low mass. Daily rates of CO2 uptake and growth in the field were calculated for one continuously stocked experiment. Both were linearly related to LAI in the range LAI 2–4·5. The agronomic implications of the results are discussed.
The reproducibility of in vivo estimates of digestibility and voluntary digestible organic matter intake of grass varieties by sheep
Authors: EVANS E. M. , POTTER J. F.
Published: April 2006

Four cocksfoot varieties were harvested at three different growth stages and offered ad libitum to yearling Clun wethers in three 24‐d feeding trials indoors over a 4‐month period. A further cocksfoot variety conserved in bulk was offered concurrently as a control feed.

The concentration of digestible organic matter in the dry matter (DOMD) and voluntary intake were measured in each feeding period. There was no significant change in the measured DOMD values between the different feeding periods. Voluntary intake of digestible organic matter (DOMI) increased over the 4‐month period for all four varieties and for the control feed. The increase in intake was greatest for the most digestible material, i.e. first‐cut harvests. Differences in DOMI were statistically significant between feeding periods for all varieties but the differences could be eliminated by correcting intakes with values from the control feed. It is concluded that comparisons of grass varieties involving intake measurements must either be made in the same feeding period or a control feed included and results corrected according to the control response.
The utilized metabolizable energy output of grassland on hill farms in Northern Ireland
Authors: McADAM J. H.
Published: April 2006

Forty hill farms in Northern Ireland were surveyed to obtain information on stocking rates and output and to identify factors affecting output. The mean farm area of 194 ha was composed of 155 ha hill land and 39 ha inbye land with a mean stocking rate of 0–7 cow‐equivalents ha−1.

On the average farm most of the grassland (88%) was over 20 years old. The preferred species content of the swards averaged 22% over the whole farm and 42% in cut swards. This latter result may be attributed to the relatively high level of fertilizer N applied to these swards (131 kg ha−1) compared to the mean application rate over the whole farm of only 29 kg N ha−1 and 93 kg ha−1 applied to the inbye land.

Output data calculated as utilized metabolizable energy (UME) per unit area for the whole farm and separately for hill and inbye components showed that although only 21% of the farm area was inbye land almost half the annual total metabolizable energy requirements of stock had to be met by grazing inbye. The capacity of herbage to meet stock energy demands was much lower on the hill with supplementary feed having to be provided over the winter.

Calculated output from inbye land was 39 GJ ha−1 compared to 7 GJ ha−1 from the hill and 15 GJ ha−1 from the whole farm. UME output of the whole farm was negatively correlated with farm size (r=−0 55) and positively correlated with stocking rate (r = 0 89), applied N level (r = 0 63)
The distribution of opaline silica bodies in the leaf sheaths of two perennial ryegrass cultivars differing in their susceptibility to attack by dipterous stem‐borers
Authors: MOORE D.
Published: April 2006

Leaf sheaths of two cultivars of perennial ryegrass were prepared by chemical oxidation so that the silica bodies in the tissues could be studied. The cultivar Fortis, which is relatively resistant to stem‐borer attack, contained many‐intercostal silica bodies in the leaf sheath but the more susceptible cultivar S24 contained few. If the pattern of silica bodies affects levels of stem‐borer infestation, it may be possible to breed for this characteristic.
Defoliation of ryegrass‐dominated swards by sheep
Authors: BARTHRAM G. T. , GRANT SHEILA A.
Published: April 2006

Patterns of defoliation in perennial ryegrass‐dominated swards were examined in two experiments. In Experiment I measurements were made on four swards after a single overnight grazing. In Experiment 2 observations were made repeatedly on marked tillers in two continuously stocked swards which were grazed down over a 24‐d period. In both experiments the chance of defoliation was related to lamina height both within and between age classes. Lamina angle was measured in Experiment 2 and within age classes the chance of defoliation was also independent of lamina angle. In Experiment 1 tillers most frequently had both of the two youngest laminae grazed; in Experiment 2 tillers with only lamina 1 grazed occurred most frequently, but defoliation of the two youngest laminae was again common.

The different frequencies of grazing of the different classes of laminae is interpreted as being a function of their frequency of occurrence within the grazed layer at the top of the sward. The pseudostem apparently restricted the depth of the grazed layer in the very short swards of Experiment 2.

Grazing behaviour in relation to sward structure and the patterns of defoliation and their implications for herbage production are discussed.
Orchardgrass and perennial ryegrass with applied nitrogen and in mixtures with legumes
Authors: SOLLENBERGER L. E. , TEMPLETON W. C. , HILL R. R.
Published: April 2006

Botanical composition of swards can markedly affect their productivity, forage quality, and acceptance by animals. The objective of this research was to determine the amounts of dry matter (DM) and N harvested in the different botanical components of swards where perennial ryegrass and orchardgrass were sown alone and fertilized with N, or sown in mixture with legumes.

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

Legume DM harvests were greater in mixtures with perennial ryegrass than in legume‐orchard‐grass swards. An exception occurred in the first year as birdsfoot trefoil harvested DM was lower in trefoil‐ryegrass swards than in trefoil orchardgrass mixtures, probably owing to vigorous competition from ryegrass in the seedling stage. As legume seed rates were increased, both the legume and grass components of mixed swards produced more DM and N. Grass DM and N harvested in orchardgrass mixtures exceeded those of ryegrass mixtures for the 3‐year period.

Sward weediness, most prevalent in pure legume stands planted at low seed rates, was sharply reduced by including either grass with the legumes. Volunteer legumes contributed to DM harvested only when the grasses were sown alone and not fertilized with N.

Species differences in crude protein (CP) concentration were significant. Birdsfoot trefoil had the highest CP of the legumes, averaging 241 g (kg DM)−1. Alfalfa and red clover averaged 219 and 208 g CP (kg DM)−1 respectively. Perennial ryegrass herbage had a higher CP concentration than that of orchardgrass in both pure and mixed swards. Grass CP increased significantly in response to fertilizer N and to higher legume seed rates.
Fertilizer and lime‐pellet requirements for seed of white clover used for improving permanent pastures†
Authors: MURPHY W. M. , DUGDALE D. T. , ROSS D. S.
Published: April 2006

Permanent pastures on acid soils in the northeastern USA produce far below their potential due to lack of legumes in the swards. This experiment was done to study the effects of lime‐pelleted white clover seed and fertilizer combinations (B, Cu, K, Mg, Mo, P, S and Zn) on clover nodulation and growth in four acid (pH 4.3–4.9), Vermont permanent‐pasture soils in the greenhouse. Potassium was applied in all treatments. Lime pelleting and Mg and P fertilization increased both proportion of plants nodulated and seedling weight. Lime pelleting resulted in the largest increase in nodulation but P application produced the greatest gain in seedling weight. Molybdenum interacted with P to enhance seedling nodulation more than either element applied alone. Phosphorus also interacted with Mg to increase seedling weight more than either one applied alone. Sulphur had no influence on seedling nodulation or yield. Applications of B, Cu and Zn depressed nodulation and yield, possibly because excessively high levels were applied. Using lime‐pelleted seed and a fertilizer combination of K. Mg. Mo and P could improve white clover establishment and growth on permanent‐pasture soils in the northeast.
An analysis of the uninterrupted growth of white clover swards receiving either biologically fixed nitrogen or nitrate in solution
Authors: ARNOTT R. A.
Published: April 2006

White clover swards were grown in a freely ventilated glasshouse during August and September 1979. The uninterrupted growth of these swards, which were grown in Perlite with either nitrate or biologically fixed nitrogen, was studied from 5 weeks after sowing until peak dry weights of the live sward components occurred. The dry weight of leaf laminae, petioles, stolons, roots, nodules and dead material was determined weekly together with live leaf numbers and leaf lamina area. The pattern of dry matter accumulation of the yield components of the swards (live leaf laminae plus petioles) was characterized by an initial period of more or less exponential growth up to 6 weeks from sowing dominated by leaf lamina development. This was followed by a linear phase, when petiole weight increased rapidly and a final slowing down period terminated by peak yields of live DM 12 weeks after sowing.

The weight of stolons, roots and nodules increased slowly during the period dominated by leaf lamina growth compared with the rapid increase thereafter, which resulted in a two‐ to three‐fold increase in the weight of stolons, roots and nodules by the time the weights peaked. It is assumed that after the leaf area index of the sward had reached a plateau there was a limit to the assimilate supply to the sward components at a stage when they were all apparently competing for photosynthates. There was a progressive slowing down in the rate of dry matter accumu‐
Set stocking, rotational grazing and forward rotational grazing by sheep on western Oregon hill pastures
Authors: WARNER J. R. , SHARROW S. H.
Published: April 2006

Data on sheep live weights, herbage standing crop and herbage quality are presented from a 3‐year grazing management study comparing set stocking, four‐paddock rotational grazing and four‐paddock forward rotational grazing systems. In both rotational grazing and forward rotational grazing systems, sheep were sequentially moved from one paddock to the next every 5 days. Lambs were weaned at 12–15 weeks of age in the forward rotationally grazed system and from then on grazed one paddock ahead of the ewes. Herbage mass was consistently greater on the rotationally grazed system than on the set‐stocked system, averaging 38.4% more herbage in 1978. 32.8% more in 1979 and 52.7% more in 1980. No differences were observed in ewe live weights at the end of the grazing year between the rotationally grazed and the set stocked systems. Live weights of rotationally grazed lambs were superior to set‐stocked lambs only when herbage allowance was low; otherwise no difference existed between these two systems. The forward rotationally grazed lambs generally had lower liveweights than did the rotationally grazed lambs, perhaps due to weaning stress.
Further development and use of an automatic recording system in sheep grazing studies
Authors: PENNING P. D. , STEEL G. L. , JOHNSON R. H.
Published: April 2006

Comparisons between some aspects of grazing and ruminating behaviour by sheep recorded automatically and by manual observation are reported.

Behaviour was recorded manually and automatically on four swards with surface heights of 3, 6, 9 and 12 cm. The automatic recording method gave significantly higher biting rates (78 v 67 ± 2·4 bites min−1) than manual recording. Possible reasons for these differences are discussed. For recordings during ruminating there was no significant difference between the two recording methods.

As sward surface height increased biting rate decreased by 4·6 (± 0.65) and 2·9 (± 0·87) bites min−1 cm−1, and masticating rate increased by 4·5 (± 1·13) and 3·7 (± 0·95) chews min−1 cm−1 for the manual and automatic recording methods respectively.

It is concluded that the automatic recording system gives higher rates for jaw movements during grazing than manual recording but there is little difference between the two methods for activities recorded during ruminating.
Effects of defoliation intensity on white clover seedling growth
Authors: BOATMAN N. D. , HAGGAR R. J.
Published: April 2006

White clover seedlings were defoliated when either two, four or six leaves had opened. There were four defoliation treatments, involving removal of younger laminae, older laminae, all laminae or all laminae and petioles, plus a control (no defoliation).

Leaf removal reduced area of subsequently emerging leaves when measured as they became fully opened, though some compensatory expansion occurred after this. Petiole length was also reduced considerably. The magnitude of these effects varied according to severity of the treatment: removal or older laminae had little effect, removal of younger laminae had a similar effect to removing all laminae, but the effect was considerably increased by removing petioles in addition to laminae. The youngest plants showed the greatest reductions in leaf size following leaf removal. Defoliation had little effect on the rate of development of subsequent leaves.

The most severe defoliation treatments reduced plant dry matter but younger seedlings appeared to have a capacity for recovery equal to or greater than that of older seedlings.

It is concluded that white clover seedlings have a considerable ability to recover from leaf removal, especially if only laminae of old leaves are removed, but the growth reduction following removal of petioles as well as laminae appears to be especially severe.
Influence of some sward characteristics on the consumption of irrigated pastures grazed by lactating dairy cattle
Authors: STOCKDALE C. R.
Published: April 2006

Pasture variables measured in eight experiments at Kyabram, Victoria were used to quantify factors influencing the consumption of irrigated pastures grazed by dairy cows. In addition, whether intake prediction equations based on sward characteristics could be developed and applied in the field was also considered.

Herbage intake (DMI) was positively related to herbage allowance (HA) in all cases; however, the increase in daily DMI achieved for every additional kg herbage offered to a cow ranged from 015 to 0·35 kg. Herbage intake was also consistently related to residual herbage (RH). For every additional tonne herbage dry matter (DM) ha−1 remaining after grazing, each cow consumed increased daily amounts of herbage ranging from 3·2 to 5·1 kg DM. However, of the other pasture variables, herbage mass (HM), pasture type (PT) and digestibility of the herbage DM on offer (DMD) influenced herbage intake less consistently.

When the data from all experiments were included together, DMI was influenced by sward characteristics in the following manner:
image
where LW = live weight of the cow (kg) and DE = duration of experiment (d).

When RH was considered instead of HA, only 61% of the variability in intake was accounted for compared to 80% when HA was considered:
image

In both of these equations, two variables other than the sward characteristics were significant; these were LW and DE. The significance of these variables in these relationships are discussed together with the possibility of using them for predicting DMI in other environments. However, it is concluded that they do not have general applicability and it is suggested that they may be useful only in the environment in which they were generated.
The future of lucerne in British agriculture: an economic assessment
Authors: DOYLE C. J. , THOMSON D. J.
Published: April 2006

With its potential for high yields and high animal output, lucerne appears to be an underexploited crop in British agriculture. In this paper an attempt is made to assess the prospects for expansion of the area of lucerne in Britain from an economic viewpoint, concentrating on lucerne as a conservation crop. Under good management lucerne is shown to have lower production costs than grass and its inclusion in the diet of dairy cows, but not beef cattle, could significantly lower winter feed costs. However, under apparently similar growing conditions, lucerne yields on different farms vary significantly, ranging from 9 to 13 t dry matter ha−1 a−1. At the lower yields, the economic attraction of growing and feeding lucerne in place of grass is small. Moreover, since potential lucerne production is concentrated in the south and east of Britain, lucerne competes with other arable crops. For lucerne to offer a gross margin per unit area comparable with these, the price for conserved lucerne would have to be set at a level at which dairy farmers would derive little economic advantage from feeding it. Thus, although lucerne is a forage crop with some potential, at present it is likely to offer economic possibilities only where producers can combine high yields with on‐farm utilization of the crop.
The effect of the growth regulator paclobutrazol (PP333) on the growth, development and yield of Lolium perenne grown for seed
Authors: HAMPTON J. G. , HEBBLETHWAITE P. D.
Published: April 2006

Application at spikelet initiation of the growth retardant paclobutrazol (PP333) at a rate of 2.0 kg a.i. ha−1 increased the seed yield of perennial ryegrass cv. S24 from 139 to 180 g m−2 in 1981, and from 111 to 256 g m−2 in 1982. Yield increases were associated with an increased production of fertile tillers in both years and with an increased number of seeds per spikelet in 1982. Other yield components were not changed. Seed yield increased with increasing PP333 application rate in both years. No significant yield difference was recorded between application at spikelet and floret initiation in 1981.

Lodging was prevented completely by the 2.0‐kg rate, delayed until after anthesis by the 1.0‐kg rate and began before anthesis with the 0.5‐kg rate. PP333 reduced stem internode length and strengthened the base of the stem; total stem dry matter (DM) was reduced, but root DM accumulation was increased at all rooting depths. Leaf area duration was significantly increased in both years.

Vegetative regrowth after seed harvest was not significantly reduced by PP333 application, but soil residual properties were demonstrated.
Eating behaviour, social dominance and voluntary intake of silage in group‐fed milking cattle
Authors: HARB M. Y. , REYNOLDS VIVIEN S. , CAMPLING R.C.
Published: April 2006

The relationships between eating behaviour, social dominance and voluntary intake of silage were examined in three experiments. Small groups of Friesian cattle were offered forage as a group in several different situations which caused different degrees of competition for silage. Restriction of the number of mangers available to the cows and of the amount of silage offered encouraged a marked increase in rate of eating silage. In Experiment I when the cows were changed from individual mangers to group feeding their mean eating rate of silage increased from 43 to 71 g silage dry matter min−1. Results from the second experiment provided confirmation. In both experiments submissive cows increased their rate of eating to a greater extent than dominant animals. When group‐fed there was no significant correlation between degree of dominance and variation between cows in voluntary intake of silage, but milk yield and live weight were often directly correlated with silage intake. In Experiment 3 cows and heifers ate similar amounts of silage per unit live weight when group‐fed.
The microclimate of an upland grassland
Authors: HAY R. K. M.
Published: April 2006

Continuous hourly measurements of air and soil temperatures, irradiance and wind velocity, and less frequent measurements of soil water status and dry matter (DM) yield were recorded over two growing seasons and the intervening winter 1978–79 for an enclosed upland grassland in Cumbria, with the aim of establishing realistic combinations of environmental factors for the design of experiments under controlled conditions. Important features of the microclimate included high diurnal and day‐to‐day variation in environmental temperature, relatively high winter soil temperatures, variation between years in the influence of altitude upon irradiance, low wind velocity throughout the year at plant height and the loss of DM yield in the early summer of 1978 due to severe drought. Combinations of environmental factors throughout the 2 years can be obtained from the figures presented; in particular, the records indicate that in growth‐cabinet or greenhouse experiments associated with the breeding or selection of cultivars for earlier DM production in spring, it is important to combine low temperatures (≤ 10°C) with realistic levels of irradiance (≥200 W m−2) and daylength (12.5–15 h).
In‐vitro dry matter digestibility and chemical composition of autumn‐accumulated tall fescue, orchardgrass and red clover
Authors: SHEEHAN W. , FONTENOT J. P. , BLASER R. E.
Published: April 2006

The objective of this study was to compare the in vitro dry matter digestibility (IVDMD) and chemical composition at various cutting dates of autumn‐accumulated tall fescue and orchard‐grass. The effect of time on the digestibility and chemical composition of accumulated red clover was also studied.

Tall fescue had significantly higher (P< 0.01) IVDMD and total non‐structural carbohydrate (TNC) levels and lower crude protein (CP), acid‐detergent fibre (ADF). lignin (LIG) and cellulose (CEL) levels throughout autumn and winter than orchardgrass. The effects of accumulation period were similar on both grasses; TNC concentrations increased up to November but then declined, with a large drop in levels after December while IVDMD decreased slowly in autumn and fell rapidly in December. Overall there was a significant (P< 0.01) increase with advancing time in ADF and CEL levels in both grasses, but LIG levels declined with age in tall fescue between 15 September and 15 November, whilst there was a general increase in LIG in orchardgrass.

In both tall fescue and orchardgrass IVDMD and TNC levels were higher (P< 0.001) and CP, ADF and CEL levels lower (P< 0.001) in the stem than in the leaf. LIG concentrations were higher in orchardgrass leaves than in the stem but the levels were similar in both fractions in tall fescue.

Similar patterns of change in IVDMD and composition were evident in red clover but the legume had completely senesced by early winter.
The effect of the brown midrib‐3 gene on the maturity and yield of forage maize
Authors: WELLER R. F. , PHIPPS R. H. , COOPER A.
Published: April 2006

Results from two trials with normal and brown midrib‐3 (bm3) types of LG11, Inra 188, Inra 240 and Inra 258 showed the bm3 mutant gene delayed silking by an average of 3 days, decreased whole plant dry matter (DM) concentration by 20 g kg−1 and the proportion of ear by 4·6 percentage units. Comparable yields of DM were obtained from normal and bm3 crops. The organic matter digestibility and yield of digestible organic matter of the bm3 plants was 0.06 units and 14% higher respectively than their normal counterparts.

Measurement of the physical strength and resistance to lodging of normal and bm3 plants showed the bm3 gene reduced stem strength, which was highly correlated to stem diameter, stem weight and rind thickness. However, the major difference in plant lodging was between genotypes with Inra 240 plants less resistant to lodging than other genotypes. These results show that although the bm3 gene slightly increased lodging, genotype susceptibility is the major contributing factor to plant lodging.
Nutrient content and phenology of cool‐season grasses of Peru*
Authors: FLOREZ A. , MALPARTIDA E. , BRYANT F. C. , WIGGERS E. P.
Published: April 2006

Changes in crude protein (CP) concentration and in vitro dry matter digestibility (IVDMD) associated with phenological development were documented for eight major cool‐season grasses on the Pampa Galeras Vicuna Reserve in the central Andes of Peru. Green‐up for most grasses occurred by late November and seed shatter occurred by late May for an average of 185 days from initiation of growth to maturation. CP and IVDMD levels were adequate for animal production from November to January for most grass species and until March for Muhlenbergia ligularis and Stipa brachyphylla. The data suggest domesticated ruminants should be managed so that greatest nutrient requirements (late gestation‐lactation) will coincide with the period of highest nutritional quality of the native grasses (November–January).
Effect of restriction of silage intake and the provision of an alternative forage on the performance of dairy cows
Authors: PHILLIPS C. J. C. , LEAVER J. D.
Published: April 2006

In three experiments the effects of restricting the silage ration of dairy cows and of offering alternative forages as buffer feeds were investigated.

In the first experiment of changeover design with 3‐week periods, restricting the intake of low‐quality silage to 0.62 of ad libitum had no significant effect on milk yield in spite of the large energy deficit. Offering high‐quality hay as a buffer feed increased total DM intake and milk production of cows receiving either restricted or ad libitum silage.

In the second experiment of similar design, restricting the DM intake of high‐quality silage to 0·58 of ad libitum significantly reduced milk yield and was associated with a large negative energy balance. Offering straw or ammonia‐treated straw with the restricted silage diet did not restore milk production to the level achieved with ad libitum silage but these supplements slightly reduced the energy deficit of the cows. In the third experiment of continuous design lasting 7 weeks, restricting the silage ration to 0.85 of ad libitum had no significant effect on milk production. Offering a strawmix based on straw, barley, molasses and soya with the restricted silage ration restored total DM intake to the ad libitum silage level.

In all three experiments milk protein content was reduced by restricting the silage ration and partially restored by offering alternative forages. There were no significant effects on milk fat content and milk lactose content was only reduced by the severest restriction in Experiment 2. It is concluded that short‐term minor restrictions of silage intake can be partly sustained by body fat mobilization but more severe restrictions will result in loss of milk yield. Good‐quality hay and a strawmix were of benefit in restoring DM and metabolizable energy intakes, whereas straw and ammonia‐treated straw were of little value.
Long‐term effects of fertilizer on the botanical composition and soil seed population of a permanent grass sward
Authors: WILLIAMS E. D.
Published: April 2006

Results are presented after 14 and 19 years of the botanical composition and seed bank of moderately fertilized or unfertilized grazed paddocks. Agrostis capillaris, Festuca rubra and broad‐leaved weeds contributed a larger proportion of the cover on unfertilized than on fertilized swards. In contrast Poa spp., Holcus lanatus, Alopecurus pratensis and Lolium perenne were relatively more abundant on the fertilized than on the unfertilized swards. A. capillaris was the most plentiful grass in the seed bank of the unfertilized swards but Poa spp. (especially P. annua) in that of the fertilized swards. Some of the relationships between the seed bank and vegetative cover are discussed and the possibility of further increasing the contribution of L. perenne highlighted.
Effect of time of application of nitrogenous fertilizer on development of white clover in an autumn‐sown mixed sward
Authors: LAIDLAW A. S.
Published: April 2006

Nitrogenous fertilizer was applied to autumn‐sown swards (soil N MAFF index 1) containing perennial ryegrass (cv. Cropper) and white clover (v. Huia) either at sowing or when nodulation was underway (38 days after sowing) at 0, 30, 60 or 120 kg N ha−1. Each treatment received 0, 45 or 90 kg ha−1 the following spring.

Nitrogen at sowing or nodulation had no effect on net rate of growth of clover plants but increased the mean number of initiated stolons per plant (mean of 17% more than unfertilized controls in late autumn) and decreased the rate of N2 fixation until late in autumn. Seed‐bed N had a greater reducing effect on N2 fixation than N applied at nodulation. Nitrogen at sowing also reduced the nodule number per plant.

Response of DM to N was not significant at the establishment harvest but was significant at the first harvest in the next year. The response to autumn applied N was lower than that to N applied in spring.

It is concluded that applied N is unlikely to be necessary for grass‐clover seed beds with an N index of 1.
The effect of harvesting system on nutrient losses during silage making. 1. Field losses
Authors: MAYNE C. S. , GORDON F. J.
Published: April 2006

An experiment was carried out during 1982 in which the effects of three differing harvesting systems on the field losses occurring during the conservation of grass as silage were examined. The treatments were either (a) harvesting herbage directly by means of a flail harvester (unwilted flail, UF), or (b) pre‐cu ing of herbage with a rotary drum mower and lifting using a precision‐chop forage harvester with wilting (WP) and without wilting (UP). Herbage was harvested on 26 May, 21 July and 7 September 1982. The mean yields of herbage produced from plots harvested by the three systems were not significantly different, with dry ma er (DM) yields of 12470, 12300 and 12230 kg ha‐1 for the UF, UP and WP treatments respectively. However, field losses with the UP and WP treatments were greater than with the UF treatment (P<0·01). As a result the yields of herbage ensiled with the UP and WP treatments, 11690 and 11320 kg DM ha‐1 respectively, were significantly lower than with the UF treatment, 12710 kg DM ha‐1 (P <0·05). Wilting of first cut herbage for a period of 72 h resulted in a significant reduction (P<0·05) in digestible organic ma er (DOM) concentration (determined in vitro), whereas small increases in DOM concentration were observed following wilting of second and third harvest material.

It is concluded that, even under favourable weather conditions, both pre‐cutting and wilting of herbage prior to harvesting can result in considerable losses of nutrients in the field.
Utilization of silage nitrogen in sheep and cows: amino acid composition of duodenal digesta and rumen microbes
Authors: CHAMBERLAIN D. G. , THOMAS P. C. , QUIG JAN
Published: April 2006

Two experiments are reported. In the first experiment the amino acid compositions of rumen bacteria and protozoa isolated from sheep given a diet of grass silage were compared with those taken from sheep given a diet of hay and barley; four sheep were assigned to each diet. There were no significant differences (P<0·05) between diets in the amino acid compositions of the microbial fractions and bacterial contents of α‐ɛ‐diaminopimelic acid were also similar for both diets.

In the second experiment the digestion of a grass silage and barley diet (65:35; 135 g CP (kg DM)‐1) was studied using four non‐lactating Ayrshire cows fitted with cannulae in the rumen and in the proximal duodenum. The mean N intake was 154 g d‐1 and the corresponding duodenal flow was 126 ± 10 g d‐1 indicating that 0·21±0·07 of the N intake was absorbed between the mouth and the duodenum. The mean rumen NH3‐N concentration was high, 297 g litre‐1, and the mean rate of microbial protein synthesis in the rumen was low, 17 g microbial N (kg OM apparently digested in the rumen)‐1. There was a low content of bacterial N in the non‐ammonia N at the duodenum (mean proportion 0·52±005) and low concentrations of methionine and lysine in the duodenal digesta protein. The results are discussed in relation to previously published data on the digestion of silage diets in sheep and to the utilization of silage diets for milk production in the cow.

It is concluded that with silage diets the supply of methionine and lysine to the duodenum is likely to be low because of the low rates of microbial protein synthesis in the rumen and that in cows those two amino acids may be limiting for milk production.
Some effect fluid‐sowing, pre‐germination, irrigation and soil covering on the establishment and growth of seedlings of white clover slot‐seeded into permanent pasture
Authors: HAYES M. J. , WILLIAMS E. D.
Published: April 2006

Seeds of white clover (Trifolium repens) were sown alone or in fluid, or pre‐germinated in fluid on to the soil surface of slots cut in an old Agrostis/Festuca sward. Seeds were left uncovered or covered with a thin layer of soil and irrigated from the outset or after 14 days delay.

With irrigation from the outset, seedlings established soonest from pre‐germinated seeds but final percentage establishment ranged only from 50 to 63% for the three states of seed. With delayed Irrigation, however, few pre‐germinated s1 survived and although germination of dry seed was delayed, final percentage establishment was unaffected. Soil covering increased establishment slightly. The number of leaves per seedling was greatest with pre‐germination and early irrigation and least with pre‐germination and delayed irrigation. Delayed irrigation also decreased the number of leaves per seedling for seedlings grown from dry seed.

The effects of early irrigation persisted so that at 84 days it significantly increased total yield of clover from all three states of seed, on average threefold, but much more from pre‐germinated than from dry seed. Soil covering greatly increased yield, especially where irrigation had been applied from the outset. The interaction of early irrigation and soil covering was even more pronounced for stolon weights, and stolon growth of Individual seedlings appeared to benefit more from soil covering than from early irrigation.

The results showed the importance of early seedling emergence, but no advantages of fluid sowing per se. They also indicated large overall beneficial effects of early irrigation and its additive interaction with soil covering.
A comparison of spectral reflectance and sward surface height measurements to estimate herbage mass and leaf area index in continuously stocked ryegrass pastures
Authors: KING J. , SIM E. M. , BARTHRAM G.T.
Published: April 2006

Measurements of sward surface height and of the ratio of light at 660 and 730 nm reflected from a pasture canopy were correlated with measurements of leaf area index (LAI) and herbage mass of two ryegrass dominant swards. Both pastures were continuously stocked by sheep to maintain a range of sward heights from 2 to 6 cm corresponding approximately to LAI 2 to 5.

Sward height appeared to be linearly related to both LAI and herbage mass, whereas 660/730 reflectance displayed a non‐linear relationship with both parameters. The accuracy of prediction by the two methods over the range LAI 1 to 3 or herbage mass 700 to 1800 kg DM ha‐1 was very similar. However, reflectance measurements could not be used above about LAI 3–4 and to this extent were less useful. Nevertheless, reflectance measurements have a potential advantage in their ability to sample large areas of pasture very quickly.
Influence of long photoperiods on the growth of timothy (Phleum pratense L.) varieties from different latitudes in northern Europe
Authors: HAY R. K. M. , PEDERSEN K.
Published: April 2006

Plants of three varieties of Phleum pratense L. from different latitudes (cv. Engmo, 69°N; cv. S48, 52°N; cv. Motim, 52°N) were grown from the five‐leaf stage at 12°C under continuous illumination or 8‐h days at essentially identical daily inputs of radiant energy. The responses to daylength extension (increase in plant dry weight, plant height and leaf dimensions and reduction in the number of tillers per plant and in tissue dry matter content) were common to all three varieties and although the enhancement in plant dry weight and in leaf size was greater in the Engmo plants, this was principally the result of poorer growth and smaller leaf size in 8‐h days. Marked differences between Engmo and the other varieties in the partitioning of dry matter within the plant were the consequence of differences in the rate of reproductive development. For example, compared with S48 and Motim, first spike emergence and 50% anthesis in the Engmo plants were delayed by 22 and 14 days, respectively, and 40% of the Engmo plants did not become reproductive even after 110 days of long‐day treatment. Furthermore, by the time that 50% anthesis of the mainstem spike had been reached by the long‐day plants of each variety, significant differences in tiller numbers and tiller fertility had developed between the varieties from high and lower latitudes. These findings and the results of previous studies of Poa pratensis, Dactylis glomerata and Bromus inermis are discussed in relation to the adaptation of high‐latitude grasses to the Scandinavian environment.
The effect of strategic fertilizer nitrogen and date of primary harvest on the productivity of a perennial ryegrass/white clover sward
Authors: FRAME J.
Published: April 2006

Four management systems involving different dates for first harvest (simulated grazing, early silage, late silage and hay) and two fertilizer N rates in spring (0 and 80 kg ha‐1) were imposed on a perennial ryegrass cv. Talbot/white clover cv. Blanca sward during 1981‐82. In each year, annual total herbage DM was increased by spring application of N but white clover production and content in the total herbage were reduced; however, white clover, which was depressed in the harvests immediately after N application, recovered during the season to amounts and contents in the total herbage similar to those given no spring N.

Annual total herbage DM production increased as the date of primary harvest was delayed (935 to 1197 t ha‐1 over two years) but mean organic matter digestibility values for the same period decreased (0‐769 to 0700). First‐harvest production made up substantial proportions of the annual production in the conservation systems. White clover, as shown by its production and the amount of stolon present, was tolerant of conservation systems, especially with no applied N.

It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. The use of strategic spring N seems a viable option, but more knowledge of rates would be valuable since this experiment only compared 80 kg ha‐1 with no applied N.