bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal patterns of grass production under cutting or continuous stocking managements
Authors: ORR R. J. , PARSONS A. J. , TREACHER T. T. , PENNING P. D. 
Published: April 2006

AbstractA comparison was made between the seasonal pattern of net herbage accumulation under cutting and the pattern of intake under continuous variable stocking on a Lolium perenne sward, which was well supplied with nitrogen fertilizer and irrigated to minimize moisture stress.The seasonal pattern of production under monthly cutting showed characteristic asymmetry with a marked peak in production in late May/early June, a rapid decline in June followed by an increase in rate in August and the total amount harvested over the season was 9–28 t organic matter ha−1.By contrast, the seasonal patterns of production on swards grazed by ewes to maintain sward surface heights of 30, 50 and 70 mm all differed fundamentally from that observed under cutting. Production was more evenly distributed throughout the season under these grazing treatments which, it has been proposed, should optimize performance. Total amounts harvested by grazing were 10–84, 10.12 and 8.51 t OM ha−1, respectively. The different patterns of production under cutting and grazing were considered to be associated with differences in the expression of reproductive development in the grass crop and the maintenance of a smaller leaf area per unit ground area under grazing.The results of the study suggest that it is not appropriate to regard the seasonal pattern of net accumulation under a standard cutting regime as representing the potential production of grass under continuous stocking. Moreover, in practice, the more uniform seasonal pattern of production seen in swards maintained on the basis of a controlled sward surface height makes it easier to match the supply of herbage to the appetite of grazing animals as the season progresses.
Competition among seedlings of phalaris, subterranean clover and white clover in diallel replacement series mixtures
Authors: HILL M. J. , GLEESON A. C. 
Published: April 2006

AbstractPhalaris, subterranean clover and white clover were grown together in binary, diallel replacement series mixtures at (day/night) 15/10 or 24/19°C under long‐day conditions, and cut at 2‐ or 4‐weekly intervals. Analysis of white clover mixtures was confined to 15/10°C due to losses of seedlings prior to imposition of treatments at 24/19°C.With white clover at 15/10°X, seedling losses occurred after the first harvest, the greater losses occurring in mixtures where subterranean clover was the major component. The de Wit analyses showed that subterranean clover excluded its companions, whereas phalaris and white clover competed for slightly different niches resulting in over‐yielding. Gleeson McGilchrist analyses showed that subterranean clover and phalaris were more aggressive than white clover under infrequent cutting, but that white clover was more aggressive as a major than as a minor component of a mixture under frequent cutting. Between phalaris and subterranean clover [he pattern of competition at 24/19°C differed from that at 15/10°C only in the more rapid development of subterranean clover and consequent swing to phalaris dominance.We conclude that the seedlings of white clover and subterranean clover are suited to combination with phalaris because phalaris is not too aggressive towards white clover, and is tolerant of the aggressiveness of subterranean clover. The survival of only a few seedlings of white clover in mixtures with subterranean clover may be sufficient for long‐term growth provided some perennation occurs after the senescence of subterranean clover.
The effects of feeding fodder beet with two levels of concentrate allocation to dairy cattle
Authors: SABRI M. S. , ROBERTS D. J. 
Published: April 2006

AbstractTwelve cows were used in a cyclic changeover design experiment to examine the effects of feeding fodder beet (variety Kyros) at three levels (0, 2 and 4 kg dry matter (DM) d−1) with two levels of concentrate feeding (4 and 8 kg DM−1). Silage was offered ad libitum. At the start of the experiment the mean number of days after calving was 46 and the mean live weight 516 kg. The experiment consisted of four 3‐week periods with intake and performance measurements during the last week of each period.An in vitro analysis of the feeds for the silage, fodder beet and concentrate respectively was: DM (g kg‐−1) 189, 163, 860; crude protein (g kg DM−1) 143,76,201; metabolizable energy (MJ kg DM−1) 104, 133, 13–5.Silage DM intake decreased but total DM intake increased when fodder beet was fed. The DM intakes (kg d−1) for treatments (fodder beet/ concentrate) 0/4, 2/4, 4/4, 0/8, 2/8, 4/8 respectively were: silage DM 91, 79, 78, 83, 70 and 68 (s.e.d. =0.31); and total DM 130, 138, 156, 162, 166, 183 (s.e.d. = 0.36). Feeding fodder beet had no significant effects on milk yield or milk composition, but there was a significant increase in milk protein yield when fodder beet was included in the ration. There were no significant interactions between level of fodder beet feeding and concentrate level. Increasing the level of concentrate feeding led to a highly significant increase in milk yield, milk protein content and yield of milk constituents. The yields for treatments 0/4, 2/4,4/4,0/8, 2/8,4/8 respectively were: milk yield (kg d−1) 206, 204,21 8, 241,235, 244 (s.e.d. = 0–58); fat yield (g d−1) 827, 793, 885, 954, 936, 954 (s.e.d. = 394); and protein yield (g d−1) 622, 628, 679, 774, 777, 814 (s.e.d. = 179). There were no significant differences in milk yield and milk composition when fodder beet was included in the diet which may have been due to the low crude protein content of the diet.
The effect of the duration of regrowth on photosynthesis, leaf death and the average rate of growth in a rotationally grazed sward
Authors: PARSONS A. J. , PENNING P. D. 
Published: April 2006

AbstractA study was made to characterize the effect of the duration of regrowth on the pattern of changes in the major physiological processes involved in the net accumulation of herbage, and so to provide a rational basis for optimizing production under rotational grazing.During regrowth following a severe defoliation, rates of canopy photosynthesis, and so the rate of production of new leaves, increased rapidly but there was a delay before there was a corresponding increase in the rate of leaf death. Although the amount available for harvest (crop live dry weight, W) continued to increase as the duration of regrowth was extended from ‘short’ (12–13 days), through ‘medium’ (19–23 days) to ‘long’ (30‐34 days), there was not a continued increase in the average growth rate – the increase in the weight of the crop, (W – Wo), divided by the duration of regrowth, t, In this study, the average growth rate (based on changes in the weight of lamina alone) increased as the duration of regrowth was extended from 12‐13 to 19‐23 days but changed little as the duration of regrowth was extended from 19‐23 days to 30‐34 days. In spring and summer, elongating stems increased the average growth rate (of lamina plus stem) up to 30‐34 days but the accumulated stem material could not reliably be harvested by sheep.A mathematical model was used to explain why the average growth rate is characteristically insensitive to the duration of regrowth beyond a given minimum duration. For practical purposes, we suggest from the results of this study that regrowths of at least 14 days but less than 28 days will be effective in achieving not only close to the maximum average growth rate of highly digestible material, but also in sustaining a densely tillered, leafy sward which regrows rapidly from severe defoliation and is more reliably harvested (utilized) by sheep.
Comparison of herbage production under continuous stocking and intermittent grazing
Authors: GRANT SHEILA A. , BARTHRAM G. T. , TORVELL LYNNE , KING J. , ELSTONJ D. A. 
Published: April 2006

AbstractThe possibility of increasing the herbage utilized over a grazing season was investigated in a study comparing continuously stocked steady‐state swards maintained at optimum height (3.5 cm) with intermittently grazed swards. The intermittent systems were designed (a) to allow periodic increase in leaf area and hence growth rate, (b)to ensure that the accumulated herbage was eaten before it senesced, and (c) lo retain high tiller density by alternating periods of herbage accumulation with periods of continuous stocking.Two treatments (no animals or animal numbers reduced to half those on the 3.5 cm steady‐state treatment) were used during the 17‐18‐d periods of herbage accumulation. Grazing down was completed in 3–4 d, after which two treatments (14 d or 28 d) were used for the intervening periods of continuous stocking when sward height was maintained at 3.5 cm.Herbage production was estimated using the tissue turnover technique, with tiller population densities and rates of growth, senescence and net production per tiller measured at frequent intervals.Intermittent grazing treatments where animals were removed during herbage accumulation resulted in changes in tiller size and number, and in growth rates, but not senescence rates, per tiller such that short‐term deviations in the net rate of herbage production occurred compared with the continuously stocked control. The periods of advantage during phases of herbage accumulation were counterbalanced by those of disadvantage during the subsequent steady‐state phases. Where animal numbers were reduced during herbage accumulation, sward conditions differed little from those of the continuously stocked control, implying that intake per individual animal was increased.It was concluded that intermittent grazing systems offered no advantage over simpler continuous stocking systems, provided that a flexible approach to conservation was incorporated to allow control of sward conditions on the grazed area.
The use of conserved forage as a supplement for grazing dairy cows
Authors: PHILLIPS C. J. C. 
Published: April 2006

AbstractThe difficulty in matching the herbage requirements of grazing dairy cows to herbage production, due mainly to the unpredictability of the latter., causes stocking rates to be too low for maximum per hectare production and, thus, cows to be underfed at certain times in the grazing season. Conserved forage may be used as a supplement for grazing dairy cows in order to reduce variation in forage intake by the cow, to allow pasture stocking rates to be increased and to increase the efficiency of land use. The effect of offering conserved forage with herbage on intakes and production is reviewed in comparison to both ad libitum and restricted herbage. Total nutrient intakes and milk fat + protein yields are reduced for cows offered herbage and supplementary forage compared with cows offered ad libitum herbage, but increased compared with cows offered a restricted herbage level. Increasing pasture stocking rates may allow increases in utilized metabolizable energy levels from grassland but further research is needed in this area. Both grass and maize silage supplements offer potential for increasing the efficiency of land use, but in the case of grass silage this is only achieved in the best management practices.
Influence of defoliation regime on herbage production and characteristics of intake by dairy cows as affected by grazing intensity
Authors: KRISTENSEN E. S. 
Published: April 2006

AbstractThree contrasting defoliation regimes for dairy cows—four cuts annually, severe rotational grazing and lax rotational grazing integrated with cutting—were compared in terms of herbage production, selection and intake per cow. Lax and severe grazing were compared simultaneously and grazing intensity was characterized by means of changes in herbage mass and sward height during grazing.Herbage growth and yield were similar under cutting, severe grazing and lax grazing/cutting (120 t organic matter (OM) ha−1). Herbage quality and leaf production were highest with severe grazing, which also had a less marked seasonal pattern of growth. The herbage intake per cow was 111 kg OM d−1 with severe grazing and proportionately (0‐20) higher at lax grazing/ cutting. 050 of the herbage yield was harvested by cutting at lax grazing/cutting. Selectivity was described with high certainly by the nutrient content prior to defoliation and by the degree of defoliation. Models to quantify this are presented.Grazing intensity could be described by the size and degree of utilization of the fouled area, and herbage intake was quantified by means of herbage height before and after grazing. Within the range of 80‐240 mm sward height prior to grazing, height measurements led to realistic and more accurate estimates than those obtained by measuring organic matter disappearance.Herbage utilization was depressed significantly by increasing maturity of herbage due to lower nutritive value, but in particular due to reduced green leaf content and increased reproductive development. If sward height did not exceed 250 mm at any time, good utilization by grazing could be obtained.
Variation in cold tolerance in Festuca rubra L.
Authors: McHUGH S. , HUMPHREYS M. O. , McNEILLY T. , JOHNSON M. S 
Published: April 2006

AbstractA laboratory assessment was made of cold tolerance in seven cultivars and one natural population of red fescue, overwintered at lowland (30 m a.s.I.) or an upland (300 m a.s.l.) site.After 5 months overwintering, plants were exposed under laboratory conditions to seven freezing temperatures, –7, –9, – 10, – 11, – 12, – 13 and – 15°C and + 2°C as control. Thawed tillers were grown in soil in glasshouse, and tiller survival and growth recorded after 28 days. Cold tolerance was estimated using LT50 values.Tiller mortality increased with decreasing freezing temperature, with almost all tillers surviving at – 7°C and almost all dying at – 15°C. Cold hardening at the overwintering site markedly affected survival, plants overwintered at the upland site having significantly greater survival than those overwintered at the lowland site. All samples were affected to similar extent by overwintering site. The samples Aber Valley, Hawk, Merlin, Polar, and Dawson were significantly more cold tolerant than Jupiter, S59, and Highlight. Tiller production data closely resembled those for tiller survival.For upland situations, eultivars or natural populations other than the currently recommended S59 have better cold tolerance, and may provide useful genetic resources for breeding cultivars for uplands use.
The effect of drainage on herbage growth and soil development
Authors: BAKER ANNE‐MARIE , YOUNGER A. , KING J. A. 
Published: April 2006

AbstractThe effects of drainage on the yield of perennial ryegrass (Lolium perenne) swards grown for silage, and on soil development under grassland, were studied between 1982 and 1985.Over the 4 years of the experiment, drainage resulted in a mean increase in herbage production of 1‐5 t dry matter (DM) ha−1, 16% above the yield recorded on the undrained site. Drainage also led to increased herbage nitrogen contents at every cut except one, so that total nitrogen recovery was increased by an average of 24‐8 kg N ha−1 (15%) when drainage was installed. These total differences were mainly due to differences that were present at the first cut taken in June each year; drainage led to an average 24% increase in yield, and an average 27% increase in nitrogen recovery at the first cut.Detailed sward measurements taken in 1985 endeavoured to explain these differences; drainage increased depth to free water over winter, enabling increased root efficiency and nitrogen availability, greater tillering and more rapid leaf extension in early spring. There was some suggestion that drainage also led to an improved topsoil structure in terms of improved aggregation and aeration. This is important for long‐term soil development as well as short‐term herbage yield.
The effect of wilting and silage additives on the fermentation of autumn made grass silage ensiled in bunkers on commercial farms in South Wales 1983‐85
Authors: HAIGH P. M. 
Published: April 2006

AbstractSilage making practices in respect of 130 samples of autumn made grass silages ensiled in bunkers on commercial farms in South Wales during 1983‐1985 were analysed to discern the effect of wilting and/or silage additives on fermentation. Silages were primarily made during late September and early October in fine weather from perennial ryegrass pasture which had not been grazed for 6 weeks. On average 13.9 ha of pasture was cut for silage. Analysis of 120 samples of grass showed it contained 176 g kg−1 dry matter (DM) with (g kg−1 DM) 215 protein, 240 modified acid detergent fibre (MADF), 78 water‐soluble carbohydrate (WSC) and 95 ash. Most farmers attempted to pre‐wilt grass for 1 day prior to ensilage and one quarter of them made unwilted silage. Silage making was usually completed within 6 days of starting to cut and was generally made with a precision‐chop machine. Silage additives applied were (kg t−1) formic acid (4·7), formic acid 4‐formalin (5·5), sulphuric acid‐+ formalin (5·0) sugars (14) and inoculants (0·65). Formic acid significantly reduced pH, and formic acid with or without formalin significantly reduced ammonia nitrogen (N) content of silages compared with other treatments. Protein contents of acid/formalin treated silages were significantly higher and MADF of acid with or without formalin treated silages were significantly lower than other treatments. Pre‐wilting grass prior to ensilage did not significantly increase subsequent silage DM content and significantly increased the pH of non‐additive treated silages. Unwilted silages treated with formic acid with or without formalin had a significantly lower ammonia‐N content and higher residual WSC than other treatments.It is suggested that only formic acid application either alone or in conjunction with formalin to unwilted silage was successful in producing well preserved silages and that a grass WSC content of 17 g kg−1 would be necessary to achieve this.
Growth of Trifolium repens L. and Trifolium semipilosum Fres. Var. glabrescens Gillet at different temperatures in controlled environments and in the field
Authors: Hill M. J. 
Published: April 2006

AbstractThe growth of Trifolium semipilosum Fres. var. glabrescens Gillet cultivar Safari, and Trifolium repens L., cultivars Haifa and Grasslands Huia was compared in controlled temperature glasshouses at 15/10, 21/16, 27/22 and 33/28°C (day/ night), and over eighteen months under four‐weekly cutting in the field. In glasshouses, white clovers grew better than Safari at all temperatures except 27/22°C. Stolon production and partitioning of dry matter to stolons was greater, and petiole production and partitioning of dry matter to petioles was less for Safari than for white clovers. Haifa and Huia differed primarily in individual leaf weight, individual leaf area and leaf numbers; with Hula and Safari, but not Haifa, exhibiting a reduction in leaf size in response lo defoliation. In the field, growth of Safari was poor. Growth responses of Haifa and Huia in the field were related to seedling vigour, dry matter partitioning between leaves and stolons, and response to defoliation at low temperatures. It was concluded that there were major differences in growth, dry matter partitioning, morphology and response to temperature between T. semipilosum and T. repens. These differences particularly influence climate adaptation and competitive ability at the seedling stage.
The use of growth regulator RSW0411 in seed crops of Lolium perenne L.
Authors: WILTSHIRE J. J. J. , HEBBLETHWAITE P. D. , ESSLEMONT R. E. , McGILLOWAY D. A. 
Published: April 2006

AbstractField trials were conducted in 1985 and 1986 to assess the effects of the growth regulator RSW0411 on a Lolium perenne L. (perennial ryegrass) seed crop. Applications were made at spikelet and floret initiation, and at 1, 2, 3 and 4 kg active ingredient ha−1.Seed yield increases in 1985 were associated with increased reproductive tiller numbers and seed numbers, but in 1986 there were no seed yield responses.Lodging was less severe in 1986, and there was less secondary filtering during seed maturation. In 1985, fertile tiller numbers were lower in control plots at harvest. These results are discussed in relation to the seasonal disparity in seed yield response.RSW0411 application significantly decreased culm lengths by shortening the basal internodes, and this effect was greater with higher application rates. Stem width was increased in 1985 at the base and middle of the stem, and earlier applications increased the basal width by more than later applications.Germination was not affected by RSW0411 treatment, except when applied at 4 kg active ingredient ha−1 in 1985, when there was a small decrease. This was related to a low 1000‐seed weight, and is discussed in relation to seed maturity at harvest.
Frequency of stocking rate adjustments required on contrasting upland perennial ryegrass pastures continuously grazed to a sward height criterion from May to July
Authors: DAVIES D. A. , FOTHERGILL M. , JONES D. 
Published: April 2006

AbstractThe use of sward height as a criterion for determining the time and extent of stocking‐rate changes on continuously grazed swards was investigated over a 2‐year period (1985–86) in a sheep production experiment. Swards of three contrasting perennial ryegrass (Lolium perenne L.) varieties were established with and without Aberystwyth S184 small‐leaved white clover (Trifolium repens L.) at an upland site (310–363 m) in mid‐Wales. From spring (late April) until weaning (mid‐July) the pastures were continuously stocked with Beulah Speckled Face ewes and Suffolk cross lambs. During this period sward heights of 4 ± 0.5 cm were obtained and maintained by regular adjustment of animal number on individual paddocks. Grass‐only swards received 160 and 200 kg N ha−1 and the grass clover swards were given 80 and 75 kg N ha−1 in 1985 and 1986 respectively.Differences were observed between the treatments in sward height profiles over the season necessitating contrasting adjustments to stocking rates. Mean stocking rate necessary on early flowering Aurora (22 6 ewes ha−1) was respectively 27% and 17% higher than on late‐flowering Aberystwyth S23 and Meltra (tetraploid) ryegrasses; mean stocking rate on grass‐only swards was 19% higher than on the grass‐clover pastures.It is concluded that sward height is a useful criterion on which to make adjustments to stocking rates to compare the potential performance of contrasting swards, under continuous grazing. The infrequent adjustments required to maintain a constant sward height, especially on the late flowering diploid perennial ryegrass variety on which many upland pastures are based, suggest that the criterion of sward height could be successfully employed on farms as an aid to efficient grazing management.