bluuebunny/crossref_metadata_2025 huggingface dataset:
Allowance‐intake relations of cattle grazing vegetative tall fescue†
Authors: DOUGHERTY C. T. , BRADLEY N. W. , LAURIAULT L. M. , ARIAS J. E. , CORNELIUS P. L.
Published: April 2006

Herbage allowance is one of the important pasture factors in the determination of intake by grazing livestock. Ingestive behaviour of 12 adult Angus cows (Bos taurus) was measured over a range of allowances (0·25 to 0·72 kg dry matter (DM) per 100 kg live weight (LW) for a 1‐h period) of vegetative tall fescue (Festuca arundinacea Schreb.). A balanced change‐over design was used to estimate direct, residual and permanent effects of herbage allowance on rate of DM intake, rate of biting and herbage DM intake per bite. In Experiment 1, herbage DM intake per meal increased linearly from 0·68 to 1·72 kg (100 kg LW)−1 as DM allowance increased from 0·25 to 0·72 kg (100 kg LW)−1 h−1. Cows grazed at ·30 kg (100 kg LW)−1 h−1 and stopped grazing when the sward was reduced to a height about 10 to 12 cm above the soil surface, approximately defined by the tops of pseudostems. In Experiment 2, herbage DM intake rates of 0·29, 0·47 and 0·42 kg (100 kg LW)−1 h−1 were recorded as cows grazed allowances of 0·43, 0·70 and 0·90 kg (100 kg LW)−1 h−1 for most of the 1‐h grazing period. Limiting herbage DM allowances in Experiment 2 were associated with small reductions in rate of biting and herbage DM intake per bite as allowance declined. Sward DM density (>5 cm) was an important variable in the determination of herbage DM intake rates at lower herbage allowances.
The performance of beef cattle given silages made from perennial ryegrasses of different maturity groups, cut on different dates
Authors: STEEN R. W. J.
Published: April 2006

Two experiments were carried out to examine the interaction between early and late‐heading varieties of ryegrass and date of harvesting of primary growths for silage in terms of the performance of beef cattle. A sward containing equal proportions of three early heading varieties (Cropper, Premo and Frances) (50% ear‐emergence on 18 May) was harvested on 20 May (T1), 28/29 May (T2) and 5/6 June (T3) and a sward containing three late‐heading varieties (Perma, Preference and Parcour) (50% ear‐emergence on 12 June) was harvested on 28/29 May (T4), 5/6 June (T5) and 12/14 June (T6) in 1985 and 1987. In each year the six silages were harvested without wilting and were ensiled in trench silos. In Experiment 1 they were offered ad libitum and unsupplemented to 48 steers (407 kg live weight (LW)) for 101 days and in Experiment 2 they were offered with 2 kg concentrates per head daily to 48 heifers (392 kg LW) for 105 days. In Experiment 1 in vivo digestible organic matter (DOMD) concentrations in dry matter were 717, 671, 643, 709, 672 and 640 (s.e. 8·4) g (kg DM)−1; silage DM intakes 7·1, 6·6, 6·6, 7·2, 7·3 and 6·7 (s.e. 0·15) kg d−1; LW gains 0·94, 0·74, 0·62, 0·90, 0·82 and 0·57 (s.e. 0·047) kg d−1; for T1 to T6 respectively. For Experiment 2, DOMD concentrations were 732, 699, 636, 734, 686 and 663 (s.e. 9·6) g (kg DM)−1; silage DM intakes 6·4, 5·7, 6·0, 6·0, 5·5 and 5·0 (s.e. 0·22) kg d−1; LW gains 1·12, 0·92, 0·99, 1·14, 0·88 and 0·76 (s.e. 0·078) kg d d−1; and carcass gains 0·66, 0·56, 0·51, 0·68, 0·55 and 0·48 (s.e. 0·048) kg d d−1; for TI to T6. It is concluded that silages made from early and late‐maturing swards of perennial ryegrass sustained similar levels of performance in beef cattle when they were harvested at equal digestibility, and the digestibility declined at similar rates for the two sward types when harvesting of the primary growths was delayed. Under the conditions of these experiments the same level of animal performance was sustained by silages made from the two swards when the late‐maturing varieties were harvested 7 days after the early varieties. This compares with an interval of 25 days between the early and late‐maturing varieties reaching 50% ear‐emergence.
Cell wall degrading enzymes for silage. 2. Aerobic stability of enzyme‐treated laboratory silages
Authors: SELMER‐OLSEN I. , HENDERSON A. R. , ROBERTSON S. , McGINN R.
Published: April 2006

The effects of two commercial cellulase/hemicellulase enzymes derived from Trichoderma reesei on silage fermentation and aerobic stability were investigated in three laboratory‐scale experiments. In Experiment 1, perennial ryegrass (Lolium perenne) was treated with enzyme A at the rates of 0. 0·125, 0·250, 0·500 and 0·750 cm3 kg‐1. In Experiment 2, Italian ryegrass (Lolium multiflorum) was treated with the same enzyme at the rates of 0, 0·250 and 0·500 cm3 kg‐1 and with 85% formic acid (3·5 cm3 kg‐1). In Experiment 3, perennial ryegrass was ensiled untreated, with enzyme A (0·250 and 0·500 cm3 kg‐1) and with 0·200 and 0·400 cm3 kg‐1 enzyme B which also contained glucose oxidase. All silages were well preserved. Aerobic deterioration was related to numbers of lactate assimilating yeasts. In Experiment 1, all silages were stable over a 4‐day period. In Experiment 2, enzyme A treatment delayed the temperature rise compared with the untreated control (P<0·05), whereas the formic acid‐treated silage was stable. In Experiment 3, the temperature rise in the silage treated with the higher level of enzyme B occurred one day later than in the other silages (P<0·05).
Management options for increasing white clover contents of swards, without resowing
Authors: SHELDRICK R. D. , LAVENDER R. H. , MARTYN T. M.
Published: April 2006

Two field experiments were carried out at North Wyke, Devon in 1985 (Experiment A) and 1986 (Experiment B) to investigate the effectiveness of either cutting or rotational sheep‐grazing managements for raising the clover content of clover‐depleted swards. Subplots were pretreated in March with (a) propyzamide at 0·4kg a.i. ha‐1, (b) chlorpyrifos at 0·72 kg a.i. ha‐1 and methiocarb at 0·22 kg a.i. ha‐1, (c) carbofuran at 1·3 kg a.i. ha‐1, or (d) not so treated, in order to reduce grass tiller density, control insect and mollusk pests, or control all invertebrate pests respectively (a‐c), Carbofuran was not applied to swards that were to be grazed subsequently. The propyzamide pretreatment (a) significantly reduced the quantity of herbage dry matter (DM) grazed and the silage DM yields in both years, but raised the numbers of active clover buds, and clover stolon density and its weight in 1986, though not in 1985, The pesticide package (b) raised the quantity of herbage DM grazed in both years, and the silage DM yield in 1986, Carbofuran (c) raised silage yields in 1985. Neither pretreatment (b) nor (c) significantly affected clover performance. In comparison with sheep grazing, cutting showed a trend to higher DM yields, and significantly raised clover stolon density and weight in both years, and active bud numbers in 1986. The periodic sheep grazing management included recovery intervals of 14 d and 35 d. In 1986 (but not 1985) the longer recovery interval raised herbage DM consumption, but had no effect on clover development. The cutting management included nitrogen inputs of either 100 kg ha‐1 in March, or none. N input raised annual DM yields in 1986 (but not 1985) but did not affect clover DM yields or performance in either year.

The experiments at North Wyke were supported by on‐farm experiments using exclosure cages at ten sites in 1985 and nine in 1986, in Yorkshire, Wales, the Midlands and Devon. In both years, application of propyzamide as in treatment (a) reduced DM yields (P<0.001) and raised the proportion of clover (P<0.001) in May harvests. The density of active clover buds (P<0.05), stolon density (P<0.001) and stolon weight (P<0.001) were increased by October. A combined carbofuran and methiocarb treatment significantly (P<0.001) increased herbage yields, but did not affect measures of clover performance. Unlike the main experiments, a comparison of grazing (outside the cages) and cutting management (within the cages) showed no effect on clover development.

It was concluded that cutting, or rotational sheep grazing with a long recovery interval, would promote clover development in the clover depleted sward. Though successful in the overall assessment, application of propyzamide gave highly variable results on different sites and was not sufficiently reliable.
Sodium fertilizer application to pasture. 4. Effects on mineral uptake and the sodium and potassium status of steers
Authors: CHIY P. C. , PHILLIPS C. J. C.
Published: April 2006

Mineral availability and status in body tissues was examined with four rumen‐fistulated steers arranged in a Latin‐square change‐over design. The steers were fed perennial ryegrass herbage from a pasture fertilized with four Na treatments: 0 (Nil), 32 (Low), 66 (Medium) or 96 (High) kg Na ha‐1 yr‐1. Na fertilizer increased herbage contents and intakes of Na, Mg and Ca but did not affect intakes of K, P and S. Herbage K:Na and K:(Ca+Mg) decreased in direct proportion to the amount of Na fertilizer applied. With increasing dietary Na intake, the Na content of saliva increased and the K content decreased. There was an increase in Na and a reciprocal decrease in K contents of rumen fluid with increasing dietary Na. Blood plasma Na contents were greater when the Na‐treated herbages were fed than in the Nil treatment. There was no effect of treatment on blood plasma K content. Increasing dietary Na increased urinary Na but did not affect urinary K. Faecal mineral concentrations of Na, Ca, P and S were increased by increasing dietary Na, whereas K content was reduced and the Mg content was unaffected. There was no difference between treatments in the proportion of mineral rapidly solubilized, except Na which increased with increasing dietary Na content. The fractional rate of degradation was greater for Na, K, and Mg than for Ca and P. Based on effective solubilization, minerals were ranked in the order K > (Mg = Na) > Ca > P, and treatments were in the order Medium > (High = Low) > Nil. Increasing Na intake increased Ca but not P or Mg availability and increased the uptake of all three minerals.
Spring defoliation of white clover seed crops. 1. Inflorescence production of contrasting white clover cultivars
Authors: MARSHALL A. H. , HOLLINGTON P. A. , HIDES D. H.
Published: April 2006

Three white clover cultivars, S184 (small‐leaved), Menna (medium‐leaved) and Olwen (large‐leaved), were sown at a seed rate of 3 kg ha‐1 under spring wheat cv. Tonic. In the spring of the two following years, there were three pre‐bud emergence mechanical defoliation treatments on which were superimposed four post‐bud emergence treatments giving a total of twelve cutting treatments. Pre‐bud emergence, plots were either cut twice (at approximately two weeks before bud emergence and at bud emergence), cut once at bud emergence or not cut. To each treatment were applied four post‐bud emergence treatments: plots were not cut or cut once (one, two or three weeks after bud emergence). Counts of the total number of inflorescences and of the proportions in various ripeness categories were made throughout the period of seed crop development to determine the pattern of inflorescence development and optimum harvest date. Overall, inflorescence numbers were greatest in cv. S184and least in cv. Olwen. Defoliation before bud emergence had no effect on inflorescence production; however, it was significantly influenced by defoliation after bud emergence. Although delaying the initial development of the crop, inflorescence numbers of all cultivars were highest in both years following cuts two and three weeks after bud emergence. Optimum harvest date was not affected by defoliation or cultivar, numbers of ripe inflorescences in both years reaching a peak at the end of August. The number of brown inflorescences, which may also contribute to seed yield, reached a peak in both years in late July. Seasonal differences in inflorescence production were again observed, emphasizing the difference between first and second year crops and importance of climate in while clover seed production. The implications of these differences in numbers and proportions of inflorescences in various ripeness categories under different defoliation regimes are discussed in relation to seed crop management in the UK.
Calibration of two techniques for estimating herbage mass
Authors: GABRIËLS P. C. J. , VAN DEN BERG J. V.
Published: April 2006

Two non‐destructive techniques for estimating herbage mass (dry matter yield) were evaluated during the growing season of 1988, from April to September. Samples were collected from four sites, with ten observations made on twenty‐five days at each site, giving a total of 612 sample units. Observations were obtained from each unit, either with a plastic rising‐plate meter (335) or with a metal rising‐plate meter (227). In addition, measurements with a single‐probe capacitance meter (Pasture Probe) were also made on all units. The usefulness of the non‐destructive methods for predicting the actual yield was evaluated by calibrating them by means of regression on the yield determined by mowing 1·5‐m2 quadrats, weighing, subsampling and drying the grass. The yield measurements were logarithmically transformed to correct for the proportionality of the residual variance with the mowed dry matter yield. Logarithmic transformation of the sensor measurements improved the linearity of the calibration relationships. The combination of one rising‐plate meter and the Pasture Probe resulted in a linear and additive model with a larger adjusted R2 than models with just one of these two sensors. The addition of the predictors ‘external moisture’ (e.g. dew), ‘day number after mowing’ and ‘site number’ significantly increased the goodness of fit of many models. In some models addition of the logarithm of the ‘dry matter percentage’ was significant. Other predictors in these models such as “Julian day number” and “grazing” proved not to be significant. The adjusted R2s in the best models for the metal and the plastic discs were 89·7% and 87·3% respectively. The corresponding coefficients of variation were 26·2% and 26·1%.

The results show that further research is necessary to refine the techniques or to develop new techniques to estimate the dry matter yield, before the sensors can be usefully integrated into a management system.
The effect of the weather on the drying rate of cut diploid and tetraploid perennial ryegrass (Lolium perenne L.) and diploid hybrid ryegrass (Lolium perenne×L. multiflorum)
Authors: ATZEMA A. J.
Published: April 2006

The drying rate of cut diploid and tetraploid perennial ryegrasses (Lolium perenne L.) and a diploid hybrid ryegrass (Lolium perenne×L. multiflorum), and associated meteorological characteristics, were studied in the field for three successive years: 1988, 1989 and 1990. Meteorological elements measured were: air temperature (at 0·1 in and 1·5 in height), dew point temperature (at 1·5m height), temperature within the grass sward, grass surface temperature, global radiation and wind speed (at 2 in height).

Apart from the weather, the drying depended on the grass species and the yield. Hybrid ryegrass had a lower initial moisture content at cutting in the morning than perennial ryegrass. Also, the hybrid ryegrass dried faster than the perennial ryegrass. Within the same varieties a low yield dried faster than a high yield. Frequent tedding did not influence the rate of drying. The temperature within the grass swath approached the air temperature at 1·5 m. The grass surface temperature was greatly affected by global radiation. Increasing wind speed had an adverse effect on the drying rate of grass.
White clover contribution to continuously stocked sheep pastures in association with contrasting perennial ryegrasses
Authors: FOTHERGILL M. , DAVIES D. A.
Published: April 2006

White clover content and herbage production in grass/clover swards were studied at contrasting altitudes in Wales. The lowland experiment (1) compared the performance of three clover varieties grown with four diploid perennial ryegrass (Lolium perenne) varieties with a range of heading dates. In the upland experiment (2) the productivity and persistence of Aberystwyth S184 (small‐leaved) clover was studied in association with three perennial ryegrasses.

In experiment I. clover content and dry matter production with Aurora (very early) ryegrass was superior to that with Frances (early), Talbot (intermediate) and Melle (late). Furthermore, the performance of Kent wild white clover (small‐leaved) was better than that of medium‐leaved Menna and Grasslands Huia. Averaged over two years (1985 and 1986) mean clover content of Kent was 22% compared with 9% and 10% of Menna and Huia.

Performance of S184 clover during the five years (1986–90) of experiment 2 was better with Meltra (late tetraploid) than with Aberystwyth S23 (late diploid) and intermediate with Aurora. Clover stolon length and growing point number declined to a low level in 1988 but increased dramatically in 1989 and 1990 after cessation of applying fertilizer N.

Results from both sites were related to animal performance data previously published. It is concluded that small‐leaved clover varieties are needed to ensure a high proportion of clover in sheep pastures and also that choice of companion ryegrass can have a significant effect on the performance of the legume component.
Effects of addition of lactic acid and post‐ruminal supplementation with casein on the nutritional value of grass silage for milk production in dairy cows
Authors: CHOUNG J.‐J. , CHAMBERLAIN D.G.
Published: April 2006

Two levels of lactic acid were added to a well‐preserved silage to give silages with three concentrations of lactic acid: 53 (control), 96 (LA‐50) and 134 (LA‐100)g (kg DM)‐1. These silages were given ad libitum with 5 kg d‐1 of a mixture of barley and soya‐bean meal (75:25) to six lactating dairy cows in a 6 × 6 Latin square design experiment to examine the effects on silage intake and milk production of the addition of lactic acid, both with and without a post‐ruminal supplement of 230 gd‐1 sodium caseinate. The six treatments were (1) control silage without casein, (2) control silage plus casein, (3) LA‐50 silage without casein, (4) LA‐50 silage plus casein, (5) LA‐100 silage without casein and (6) LA‐100 silage plus casein. Sodium caseinate was administered as a continuous infusion into the abomasum. Periods were 14d long.

Both levels of addition of lactic acid reduced (P < 0·001) the intake of silage, values being 102, 94 and 86 kg DM d‐1 for the control, LA‐50 and LA‐100 treatments respectively, but the casein supplement did not affect the intake of silage. Milk yield was reduced (P < 0·01) only for treatment LA‐100 and, for this treatment, was restored (P < 0·01) by casein given post‐ruminally. With all three silage treatments, casein infusion increased (P<0·001) the yield of protein in milk by 30–35 gd‐1. The concentration of protein in milk increased linearly (P < 0·001) with the addition of lactic acid to the silage.

The addition of lactic acid produced a linear reduction (P < 0·001) in the molar proportion of acetate in rumen contents and compensatory linear increases (P < 0·001) in the molar proportions of propionate and butyrate. Changes during the day in the concentration of insulin in blood plasma followed a similar pattern to changes in the molar proportions of propionate. The mean daily concentration of insulin in plasma tended (0·10 < P > 0·05) to be higher for the LA‐100 treatment, and in the immediate period after feeding this difference was significant (P < 0·05).

The results confirm the effect of lactic acid in depressing the intake of silage, but they offer no support for the hypothesis that the depression of intake can be offset by an increase in the supply of protein post‐ruminally.
The potential for control of the soft rush (Juncus effusus) in grass pasture by grazing goats
Authors: MERCHANT M.
Published: April 2006

Two experiments were conducted to examine the effect of inter‐tussock grass height and stocking rate on the utilization of the rush (Juncus effusus) by grazing goats. In the first experiment, on rush‐infested Festuca rubralTrifolium repens pasture, the utilization of rushes by goats grazing at a sward height of 3–4cm or 5–6cm was compared with that occurring on plots grazed by sheep at a sward height of 3–4 cm. Sheep grazed minimal amounts of rush. In contrast, it was estimated that 90% and 75% of current seasons growth of rush was grazed by goats at sward heights of 3–4 and 5–6 cm respectively during the first year. With continued goat grazing at 5–6cm there was a dramatic reduction in the cover and vigour of the rushes, and at a sward height of 3–4cm established tussocks were eliminated from the pasture.

The second experiment compared the utilization of rushes invading predominantly Agrostis swards stocked with goals at 10, 20 or 30 ha‐1 and in which inter‐tussock sward height was maintained at 4–5cm on all treatments, by adding or subtracting sheep. On one site rush utilization increased with the increase in stocking rate of goats and rush tussocks were eliminated within 3 years at 30 goats ha‐1. On another, there was no difference between plots stocked at 20 or 30 goats ha‐1 and viable tussocks remained. The influence of the composition and productivity of the inter‐tussock herbage and the proportion of rush in the biomass are discussed.

Goats can be used lo control rushes in grassland but high stocking levels and low inter‐tussock pasture heights are required to promote adequate levels of utilization.
Intake and digestibility of components of forage rape (Brassica napus) by sheep
Authors: ARMSTRONG R. H. , BEATTIE M. M. , ROBERTSON E.
Published: April 2006

Herbage from forage rape (Brassica napus cv. Lair), harvested in the autumn, was separated into different morphological components and offered ad libitum to weaned lambs and adult sheep in two indoor pen‐feeding experiments. In vivo. digestibility and the voluntary intake of herbage components were measured and related to chemical composition and in vitro digestibility. The organic matter digestibility of all plant components, especially of petiole, was high; lamina, 0·847: petiole, 0·892; upper stem. 0·865; lower stem, 0·771. Lambs and adults digested ‘leaf’ (0·83) vs 0·846) or ‘stem’ (0·782 vs 0·789) equally well. Both lambs and adults ate much less of the components or of whole crop than would be predicted with grass crops of similar digestibility or fibre content. With the exception of lamina, intake was closely related positively to digestibility and negatively lo fibre content. Low intakes of lamina were associated with high concentrations of glucosinolates. In vitro digestibility values obtained on small samples of forage show that the process is adequate for the prediction of in vivo digestibility.
The fine‐scale mapping of grassland protein densities
Authors: CLIFTON K. E. , BRADBURY J. W. , VEHRENCAMP S. L.
Published: April 2006

A simple and accurate remote sensing technique for the fine‐scale mapping of grassland protein densities was developed during a study of sward quality and antelope dispersion in Kenya, East Africa. Using measures of spectral reflectance and a vehicular navigation system, estimates of protein densities were recorded at rates exceeding 1000 samples per hour. Nitrogen analyses confirmed that reflectance measures were accurate predictors of protein density for a variety of grass swards but not for two species of sedge. Because the regression coefficients linking reflectance to protein density differed significantly between sward types, good estimates using this method will require a separate calibration for each type of grassland. By monitoring and correcting for variations in ambient light levels, the method can be used under a wide range of lighting conditions and for long periods. This facilitates sampling sufficiently systematically and intensively that contour plots of protein density can be constructed and then correlated with distributions of underlying abiotic factors, foraging activity of sympatric herbivores, or prior maps to characterize successional and historical change.
Growth of prairie grass (Bromus willdenowii) and tall fescue × perennial ryegrass (Festuca arundinacea×Lolium perenne) on the Appalachian Plateau of southern West Virginia, USA
Authors: BELESKY D. P. , STOUT W. L.
Published: April 2006

The productivity and persistence of prairie grass (Bromus willdenowii Kunth) cv. Grasslands Matua were compared with a similarly managed endophyte‐free tall fescue × perennial ryegrass hybrid (Festuca arundinacea Schreb. ×Lolium perenne L.) cv. Johnstone. A field study was conducted on the Appalachian Plateau of southern West Virginia, USA (81°W, longitude; 38°N, latitude; 850m above sea level) for three consecutive years. Nitrogen totalling 0, 168, and 336 kg N ha−1 year−1 was applied to stands managed as hay. Annual herbage yields were similar for both species in year 1 (1989), but by year 3 (1991) Matua sown‐grass yield was about 35% of first‐year yields. Total herbage yield for Matua plots in the third year was similar to first‐year yields owing to encroachment by non‐seeded grasses and white clover (Trifolium repens L.). Matua was susceptible to powdery mildew [Blumeria graminis (DC) E. O. Speer] in this environment, and was similar in productivity (first year only) and nutritive quality to tall fescue × perennial ryegrass hybrid. Matua use may be limited to areas where low‐temperature stress and resultant winter damage is unlikely to occur.
Effects of feeding fodder beet and concentrates with different protein contents on dairy cows offered silage ad libitum
Authors: FISHER G. E. J. , SABRI M. S. , ROBERTS D. J.
Published: April 2006

In two changeover design experiments, fifteen early‐ and sixteen late‐lactation cows were used to investigate the effects of offering food beet with ad libitum grass silage and concentrates with different CP content on milk yield and quality. In Experiment 1 (early lactation) cows were offered no fodder beet (0) or 4 kg DM d−1 (4) in conjunction with one of three concentrates containing 159, 191 or 244g CP kg−1 DM (L.M.H.). Treatments were therefore 1L/0, 1L/4, 1M/0, 1M/4, 1H/0 and 1H/4. In Experiment 2 (late lactation) cows were offered the same level of fodder beet in conjunction with two concentrates containing 129 and 229 (L,H) g CP kg−1 DM. Treatments were therefore 2L/0, 2L/4, 2H/0 and 2H/4.

In both experiments feeding fodder beet reduced silage DM intakes (P < 0·001) and increased total DM intake (P < 0·05 to P < 0·001). The substitution rate (r) ranged from 0·46 to 0·59kg of silage DM (kg−1 fodder beet DM).

In Experiment 1, fodder beet tended to increase milk yield, composition and yield of constituents, but the effect was statistically significant for milk protein content only (P < 0·01). In Experiment 2, milk yields for 2L/0, 2L/4, 2H/0 and 2H/4 were 11·3, 12·1, 11·7 and 12·5 kg d−1 respectively (s.e.d. 0·43, non‐significant), fat contents were 44·4, 47·3, 44·3 and 46·8g fat kg−1 respectively (s.e.d. 0·73, P < 0·001), protein contents were 34·3, 35·6, 35·3 and 36·2 g protein kg−1 respectively (s.e.d. 0·28, P < 0·001), fat yields were 494, 574, 512 and 579 g fat d−1 respectively (s.e.d. 20, P < 0·001) and protein yields were 385, 426, 407 and 442 g protein d−1 (s.e.d. 13, P < 0·01) respectively.

Increasing CP in the concentrate significantly increased milk yield in Experiment 1 (23·9, 22·5, 23·5, 23·8, 26·2, 26·5kg d−1 for 1L/0, 1L/4, 1M/0, 1M/4, 1H/0 and 1H/4 respectively, P < 0·05). Higher CP in concentrate also resulted in significantly increased milk protein yield in early‐lactation (P < 0·001) and milk protein content in late‐lactation (P < 0·01) cows. There was a significant interaction between fodder beet and concentrate CP content for milk protein yield (P < 0·001) in Experiment 1.
Yield and composition of red clover treated with growth regulators in early spring
Authors: NARASIMHALU P. , KUNELIUS H. T.
Published: April 2006

The effect of growth regulators on the yield and quality of red clover (Trifolium pratense L.) was assessed in two growing seasons. An early‐flowering cultivar (Florex) and a late‐flowering one (Altaswede) were treated with the growth regulator, daminozide butanedioic acid [mono (2,2‐dimethylhydnizide)] or mefluidide [N‐(2,4‐dimethyl‐5{[(trifluoromethyl)sulphonyl]amino}phenyl) acetamide], either in early (mid‐May) or late (late May) season and at low rate [daminozide, 4kg active ingredient (a.i.) ha−1; or mefluidide, 0·13 kg a.i. ha−1] or twice the low rate (high rate), and compared with no treatment. Red clover yielded two‐ to three‐fold more dry mater (DM) in the first than in the second harvest, and growth regulator treatments did not redistribute yields more evenly between the two harvests. Growth regulator effects on the yield and composition of red clover were mainly confined to the first cut herbage. Daminozide increased first‐cut and annual yields of DM and in vitro digestible DM (TVD); the latter was increased particularly for Altaswede, as compared with the untreated red clover. Mefluidide decreased first‐cut yields of DM and IVD for Florex only, but the annual yields for both cultivars were unchanged by this treatment. Changing the rate or time of growth regulator application did not affect DM or IVD yield in red clover. The treated red clover contained less water‐soluble carbohydrate in the first cut than did the untreated crop. The high rate of daminozide, when applied early, decreased neutral detergent fibre and increased IVD contents in the first‐cut red clover compared with the other combinations of rate and time. Altaswede produced as much DM annually and had a higher IVD content than Florex when these cultivars were cut on common dates, twice during the short growing season in Atlantic Canada.
The productivity and response to inorganic fertilizers of species‐rich wetland hay meadows on the Somerset Moors: nitrogen response under hay cutting and aftermath grazing
Authors: KIRKHAM F. W. , WILKINS R. J.
Published: April 2006

The productivity and response to fertilizer nitrogen (N) was measured in herb‐rich wetland hay meadows within a Site of Special Scientific Interest (SSSI) in Somerset, UK. Output from hay cut after 1 July each year and from beef production at aftermath grazing was measured over a total of 4 years.

Total utilized metabolizable energy (UME) output averaged from 40·6 GJ ha−1 year−1 without fertilizers to 61·7GJha−1 at 200kgNha−1 (N‐200), the highest rate used, with about two‐thirds of this output from hay. N response was markedly curvilinear above about 50kgN ha−1, but data from a concurrent experiment suggested that the comparatively low replacement rates of P and K applied were limiting at higher N rates. When hay cutting was delayed until early August in a wet year, yield response to N was lost because fertilized swards had passed a peak in yield several weeks before harvest.

Compared with other published data, the results suggest that output and response to N is not constrained by the diversity of the flora or the damp conditions. The data will help to estimate the financial implications for farmers of restricted or zero fertilizer use within SSSIs and the wider Environmentally Sensitive Areas.
Patterns of nodal rooting in Trifolium repens (L.) and correlations with stages in the development of axillary buds
Authors: NEWTON P. C. D. , HAY M. J. M.
Published: April 2006

Forty per cent of while clover nodes had roots when a pasture was rotationally grazed by sheep compared with 29% when grazed continuously by set stocking. Nodal roots were most frequent during spring and least frequent during summer. About 5% of nodes had a root primordium which had not developed but was still viable. A high proportion of nodal roots (66%) occurred within 10 nodes of the apex. Root presence was highly correlated with the establishment and survival of branches but was less closely related to branch initiation or the viability of axillary buds. It is suggested that the association between nodal roots and branches is strongest when resources are limited, and that root survival at a node is enhanced by the presence of a branch originating at the same node.
Establishment of lucerne after maize in conservation tillage systems†
Authors: BYERS R. A. , BAHLER C. C. , STOUT W. L. , LEATH K. T. , HOFFMANN L. D.
Published: April 2006

Extensive slug damage reported for lucerne (Medicago sativa L.) establishment in grass sod and small grain fields when using conservation tillage prompted this 3‐year study on establishing lucerne in maize (Zea mays L.). Different crop residues were created by harvesting maize for grain and silage and including a silage+rye (Secale cereale L.) winter cover crop treatment. Conventional tillage (ploughed in spring) following grain harvest was included as a control. In addition, a combination treatment of methiocarb bait broadcast on the surface and carbofuran granules applied in the furrow with the seed was compared with an untreated control. Finally, three planting dates, early and late April and late May, simulated the spring planting season. Planting lucerne in the different maize residues had a significant effect on lucerne yields, especially the silage+rye residue treatment, which caused the lowest lucerne yields. Highest yields of lucerne occurred when it was planted after silage, a treatment in which residue was minimal.

The earliest planting date gave the highest lucerne yields in the establishment year. Slugs did not reduce the establishment of lucerne in any maize residue, nor were lucerne yields affected by slug feeding. This was attributed to the low slug populations observed early in the growing season. Establishing and producing lucerne in maize residues was more successful in this study because of the lower slug populations than those usually encountered in grass sod or small grain residues.
The effect upon fermentation and nutritive value of silages produced after treatment by three different inoculants of lactic acid bacteria applied alone or in combination
Authors: ROOKE J. A. , KAFILZADEH F.
Published: April 2006

Silages were made from the first cut of a predominantly perennial ryegrass sward. The silages were either untreated (W) or treated with formic acid (31 t−1, F) or with 106 lactic acid bacteria (LAB) g−1 grass of each of three strains alone (A. Lactobacillus plantarum MTD1; B, Pediococcus species 6A2; C, L. plantarum 6A6) or in combination (AB. AC) to give seven treatments. The silage fermentation in 10‐kg silos was followed chemically and microbiologically and the nutritive value of selected treatments evaluated using 2‐t silos.

The control silage (W) fermented well. Addition of formic acid restricted fermentation and produced a silage with a high ethanol concentration. After day 4, all inoculated silages had lower pH values and higher lactic acid concentrations and a higher ratio of lactic acid to acetic acid than the control silage. Chemically there was little difference between the inoculated silages in terms of final composition. Microbiologically the LAB applied in treatments B and C dominated the LAB populations in those silages when applied alone; however, they were suppressed when applied in combination with inoculant A.

When fed to sheep, the intake of the formic acid‐treated silage was significantly (P < 0·01) lower than that of the other silages and the intake of silage treated with inoculant A significantly (P < 0·001) higher than that of silages treated with inoculants B and C. The apparent organic matter (P < 0·001) and nitrogen (P < 0·01) digestibilities of the formic acid‐treated silage were also significantly lower than those of the other silages.
Effect of plant age and severity of defoliation on regrowth of sheep's burnet during substrate moisture depletion
Authors: DOUGLAS G. B. , ROBERTSON A. G. , CHU A. C. P. , GORDON I. L.
Published: April 2006

Regrowth of 3‐ and 4‐month old (‘young’ and ‘old’ respectively) sheep's burnet [Sanguisorba minor ssp. muricata (Spach) Briq.] was studied under limiting and non‐limiting moisture conditions in a glasshouse. Moisture deficits were imposed by using a single cycle of withholding moisture until first wilting. Plants of each age were defoliated severely at three levels which represented approximately 80–100% canopy removal. These levels were based on the proportion retained of the eight most mature leaves on each plant and were referred to as complete [0% residual leaf area (rLA)] and partial [50% rLA (four leaves) and 100% rLA (eight leaves)] defoliation. Vegetative growth and total non‐structural carbohydrate (TNC) levels were studied.

Leaf number (0‐8 leaves), area (0‐115 cm2) and dry weight (0‐1·0 g) differed (P < 0·05) between defoliation intensities at the start of regrowth, while stubble (1·2 g) and root (12.·6 g) dry weights were similar. Soluble sugars [< 6% dry matter (DM)] and starch (< 1% DM) occurred in leaf, stubble and root. Old plants were morphologically and physiologically more developed than young plants. For example, stubble (2·0 g) and root (21·5 g) dry weights of old plants were greater (P < 0·05) than those of young plants (04 and 3·7 g respectively).

Defoliation intensity had a major effect on regrowth, with completely defoliated plants at the final harvest having leaf numbers (forty‐nine leaves) and areas (235 cm2) almost twice those of partially defoliated plants. Stubble soluble sugar levels (38% DM) were lower than those of partially defoliated plants (5·5% DM), and it was suggested that these contributed to regrowth. Moisture regime had a negligible influence on plant growth. However, plants in the dry regime had soluble sugar levels 1·4 (stubble) ‐1·7 (roots) times higher than those watered adequately, which suggested that plants adjusted to the water depletion. The effects of plant age on regrowth were similar for most characters, but the larger and physiologically more mature old plants would probably be more tolerant of successive defoliations.
Leaf number as a criterion for determining defoliation time for Lolium perenne, 1. Effect of water‐soluble carbohydrates and senescence
Authors: FULKERSON W. J. , SLACK K.
Published: April 2006

This study sought to define the optimum defoliation interval for Lolium perenne, with the maximum interval being determined by the onset of senescence, as reflected by the number of fully expanded leaves, and the minimum interval set by the replenishment of water‐soluble carbohydrates (WSCs).

In a glasshouse set at 13°C/23°C night/day temperature and at a plant spacing of 94 m−2 (3290 tillers m−2), the accumulation of dry matter against leaf number and days was exponential to the four‐leaf stage of the regrowth cycle. Senescence commenced at the 3·5‐leaf stage.

WSCs in roots, stubble and leaf showed a very significant linear relationship with leaf number. Levels of WSCs in leaves were restored to predefoliation values by the one‐leaf stage, after which WSCs accumulated preferentially in the stubble, rising to 22% at the four‐leaf stage.

Regrowth after 6 d was significantly greater for plants defoliated at the three‐leaf stage than at the one‐leaf stage, but this difference disappeared at the end of the regrowth cycle. This questions the importance of WSCs in determining the yield of ryegrass under normal rotational grazing management.

Regrowth at 6 d was related positively to stubble WSCs (r2= 0·66) and to stubble DM per tiller(r2=0·71)
Effect of spreading method, application rate and dilution on ammonia volatilization from cattle slurry
Authors: FROST J. P.
Published: April 2006

Results from a series of five small‐scale plot experiments which simulated different strategies for lowering ammonia volatilization following slurry application to grassland are reported. Strategies studied were band spreading, shallow‐channel application, spike injection, rate of surface application and dilution. Volatilization was measured over the first 4 h following application with ventilated enclosures. Band spread slurry resulted in 0·4 of the volatilization that occurred from surface application of the same rate of slurry. The benefit of band spreading was shown to arise from higher application rates in the bands when compared with the same quantity of slurry spread over the surface. When surface‐spread slurry was applied to the same depth of slurry as in bands, the volatilization per unit volume of slurry was the same. Shallow‐channel application was more effective than band spreading and lowered volatilization per unit volume of slurry to <0·1 of that from surface‐spread slurry. Spike injection was equally effective as shallow‐channel application but, owing to perceived difficulties in machine design, construction and operation, was deemed impractical. Shallow‐channel application has potential, though further work is required to optimize centre‐to‐centre spacing of the channels. As the application rate of surface‐applied raw slurry increased, ammonia volatilization per unit volume of slurry applied decreased. Application at 50 m3 ha−1 resulted in 0·4 of the specific volatilization per unit volume of slurry that occurred at 6·3 m3 ha−1. Within the dilution treatments, the amount of water added to the slurry was linearly and inversely related to volatilization. At a dilution of 0·9‐1·2:1 water: slurry the specific volatilization per unit volume of slurry was 0·5 of that from undiluted slurry.
The influence of soil factors on the growth of a grass/clover sward on a restored opencast site in Northumberland, UK
Authors: CHAPMAN R. , YOUNGER A. , DAVIES R.
Published: April 2006

The growth of grass and clover components in mixed swards on a site restored after opencast coal mining and an undisturbed control site were compared. Soil nitrogen supply was reduced at the restored site. This inhibited grass growth but was beneficial for the clover component.

Growth at the restored site was also inhibited by a compacted subsoil, which reduced available soil water content and impeded access to available soil water. This inhibited crop production from the middle of the second silage crop onwards. In 1989 this was associated with the soil at the restored site reaching permanent wilting point at 40cm. In 1990 this effect was associated with the restored site soil reaching permanent wilting point at 70cm. These drought effects reduced clover growing point population and stolon mass. Grass tiller populations were unaffected.
The effect of hydrogen cyanide potential (HCNp) and sward morphology on the relative acceptability to sheep of white clover and Caucasian clover herbage
Authors: HILL M. J. , HOCKNEY M. J. , MULCAHY C. A. , RAPP G.
Published: April 2006

The effect of cyanide concentration and plant morphology on the relative acceptability to sheep of fifteen cultivars of Trifolium repens and one cultivar one cultivar of Trifolium ambiguum were assessed in a field trial at Armidale, Australia (30°S). Preference was shown for the taller, larger leaved cultivars of white clover such as Lucky. Regal, Haifa, Aran, Olwen, and for Monaro Caucasian clover, when differences in leaf size and height were most accentuated. Dry matter consumption was a poor indicator of preference. Acceptability measures were not well‐correlated with HCNp. Cyanide contents increased from January to April, but were considerably lower in July and November. Aran and Olwen had consistently the highest HCNp while Lucky, Regal and Monaro had the lowest HCNp. Sulphur contents were always high (> 2%) and varied only slightly between cultivars. Sheep preferred clover cultivars that were easiest lo harvest; these were large leaved, tall types. However, once the obvious differences in ease of harvesting were removed, sheep grazed opportunistically. Since HCNp had no effect on acceptability, breeders should aim for cultivars with moderate to low HCNp to retain pest protection but minimize goitrogenic potential. Caucasian clover exhibited a different growth pattern to white clover but its acceptability was similar.
A non‐destructive method for estimating lucerne shoot weights
Authors: SIMONS R. G.
Published: April 2006

Estimates of leaf and internode weight, leaf appearance rate and shoot number are not appropriate for non‐destructive determinations of lucerne (Medicago sativa) growth rates as they are too variable. In an experiment involving four cultivars of lucerne harvested on two dates, a good relationship was found between linear measurements and the dry weight of shoots. An equation of the form W1/3= a.(dl*d2*length)1/3, where W = dry weight; dl, d2 = two diameters of the basal end of the shoot; length = maximum length of the shoot; and a = constant, gave a good fit to the data. The value of a varied between cultivars and sampling dates, and in the proportion of shoot harvested. The product of estimated shoot weight and shoot number can be used to give an estimate of plot yield.
Independence of dry matter yield and leaf yield among perennial ryegrass varieties differing in seasonal yield distribution
Authors: WILKINS P. W.
Published: April 2006

Four varieties of perennial ryegrass (Lolium perenne L.), (Ba11316, Merlinda, Morgana and Talbot), with similar ear emergence dates but differing in seasonal yield distribution were compared over two harvest years (1992 and 1993) in a small plot trial employing six levels of fertilizer N (100 to 600kg Nha−1 year−1 applied monthly as split dressings). In each year, a conservation cut in May was followed by five further harvests at monthly intervals. Herbage samples from each of the twelve harvests were separated into leaf lamina and other tissues, and the yield of leaf lamina calculated. The percentage of flowering tillers was determined in May and July of each year, Ba11316 produced significantly more dry matter (DM) than the other three varieties at six of the twelve harvests, but its total DM yield over all twelve harvests was 5% less than Merlinda and 3% less than Morgana, owing to lower yields of reproductive growth in May of both years. Varieties also varied in mean leaf content of the herbage over all harvests, Ba11316 being 69 g kg−1 higher than that of Merlinda. Differences among the varieties in leaf content were primarily because of difference in proportion of flowering tillers, Ba 11316 having a lower proportion of flowering tillers than the other three varieties. However, the mean leaf content of the tetraploid Merlinda was significantly lower than that of Morgana although these two varieties had a similar mean percentage of flowering tillers. Despite its lower total DM yield, Bal 1316 produced 16% and 14% more leaf over the two harvest years than Merlinda and Morgana respectively. Total leaf yield of Talbot was significantly higher than that of Merlinda and Morgana, although Talbot had been developed twelve years earlier than the other two varieties.
A mathematical model of the aerobic deterioration of big‐hale silage and its implications for the growth of Listeria monocytogenes
Authors: RUXTON G. D. , GIBSON G. J.
Published: April 2006

Aerobically spoiled silage has often been shown to harbour dangerously high levels of Listeria monocytogenes. This paper investigates the dynamics of aerobic deterioration in a silage bale as it occurs close to a site of damage to the cover. The underlying aim was to enable prediction of the extent of the silage that may become suitable for Listeria growth during the course of storage. In order to meet these objectives, a model was formulated that represents the microbiology of the deterioration process and the transport of oxygen and heat through the silage. The geometry of the system was exploited to ensure that the model is computationally tractable. The model was used to evaluate the effect of silage pH and puncture size on the risk of Listeria contamination. Although the hazardous fraction was seen to be relatively insensitive to the initial pH of the silage, it increased rapidly with puncture size. However, a small puncture can result in the ‘loss’ of a considerable fraction of the bale because of the relatively long time scale over which bales are stored.