bluuebunny/crossref_metadata_2025 huggingface dataset:
Limitations of the electronic capacitance meter in measuring yields of grazed tropical pastures
Authors: JONES R. M. , SANDLAND R. L. , BUNCH G. A.
Published: April 2006

Relationships between readings of the electronic (capacitance) pasture meter and descriptions of pasture yield were examined over the yearly growth cycle in grazed pastures of Setaria anceps cv. Nandi, with or without Macroptilium atropurpurem cv. Siratro and Desmodium intortum cv. Greenleaf. There was a poor relationship between meter reading and pasture dry matter yield (r =+0.574 pooled over pastures and seasons) but this relationship was improved to r=+0.750 by inclusion of other regressors describing pasture height and proportion of inert material. Meter reading was more closely related to fresh pasture yield (r =+0.830), water yield (r =+0.885) or dried green yield (r =+0.830), although inclusion of a pasture height term still improved the relationship slightly. Suggestions are made about using the meter to estimate dried green yield rather than total dry matter yield, and taking more consideration of the proportion of inert material when relating the meter reading to total dry matter yield.

Visual estimation was also compared with actual pasture yield measured by cutting. Even though prior training for yield estimation was inadequate, the relationships between visually estimated and actual yield were as good as those from the pasture meter. It is concluded that the pasture meter will not find a regular use as a sampling tool in most grazed tropical pastures.
Effect of supplementary concentrates on performance of early‐weaned lambs at pasture
Authors: MARSH R. , CHESTNUTT D.M.B.
Published: April 2006

Two experiments in which early‐weaned lambs (4–7 and 5–9 weeks of age) continuously grazed a perennial ryegrass‐white clover sward are described. In both experiments groups of lambs were offered a proprietary concentrate ad libitum, 2/3 or 1/3 of ad libitum allowance, or no concentrate. Mean daily gains over 56 days in Experiment 1 increased from 88 g without concentrate to 275 g with ad libitum concentrate allowance; the range in daily gains over 71 days in Experiment 2 was 201 g to 253 g respectively. In both experiments mean faecal OM output from herbage decreased as concentrate OM intake increased.
A comparison of methods of predicting the in vivo digestibility of heather by sheep
Authors: MILNE J. A.
Published: April 2006

Methods of predicting the in vivo dry matter digestibility (DMD) of heather were examined in studies on ten samples of heather which had been fed to sheep in standard digestibility trials. DMD was predicted with similar accuracy from estimates of in vitro dry matter digestibility (in vitro DMD) and from the concentration of cell‐wall constituents.

In vitro DMD was found to be between 10 and 18 percentage units lower than DMD. Freeze drying the samples was the only modification to the technique which both increased in vitro DMD and the accuracy of the prediction of DMD. Other modifications attempted were the use of different liquor sources, changes in first‐stage incubation time and dilution rate, and nitrogen supplementation of the inocula.

The concentration of nitrogen or undigested dietary nitrogen in the faeces could not be used to predict the digestibility of heather with precision. It was concluded that the DMD of a heather diet could be satisfactorily predicted from the in vitro DMD of samples collected from sheep fistulated at the oesophagus.
Silage and milk production: a comparison between additives for silage of high digestibility
Authors: CASTLE M. E. , RETTER W. C. , WATSON J. N.
Published: April 2006

Three grass silages made in early June from S23 perennial ryegrass were compared in a 16‐week feeding experiment with twelve Ayrshire cows. The silages were made from uniform herbage which received either formic acid (‘Add‐F’) at the rate of 201 t−1, or a formalin‐sulphuric acid mixture (‘Syiade’) at rates of 2.0 and 4.4 1 t−1. The silages were offered ad libitum either alone or supplemented with a cube containing 38% CP in the DM at the rate of 1.4 kg per 10 kg milk. The daily intakes of silage DM were not significantly different on the three silage treatments, and averaged 10.7, 11.0 and 11.0 kg per cow on the formic acid and the 2.0 and 44 1 t−1 formalin‐acid treatments respectively. The mean daily yields of milk were 15.1, 13.3 and 13.7 kg per cow in the unsupplemented treatments, and 18.2, 18.1 and 18.0 kg per cow in the supplemented treatments on the formic acid and the 2.0 and 44 1 t−1 formalin‐acid treatments respectively.

On the basis of total animal production expressed in terms of metabolizable energy requirements, it was concluded that the differences between the three silages were small.
The influence of autxunn cutting regime on the response to temperature of leof growth in perennial ryegrass
Authors: THOMAS HENRY
Published: April 2006

Plots of perennial ryegrass were cut in September, October, November and December 1975, and soil surface temperature, leof extension rates, appearance rates and lengths were measured between September 1975 and April 1976.

Cutting on progressively later dates in the autumn reduced leof extension rates and leof lengths throughout the following winter and spring, whereas leof appearance rates were reduced for only about 1 month ofter cutting.
An evaluation of a high‐quality grass silage for milk production
Authors: GORDON F. J. , MURDOCH J. C.
Published: April 2006

Forty British Friesian cows with a mean calving date of 28 January were used in a randomized block design experiment to evaluate a high‐quality grass silage for milk production. The high‐quality silage was made from two consecutive cuts of a perennial ryegrass sward after regrowth intervals of 37 days, wilted to 51% dry matter, finely chopped and ensiled using 2.2 1 t‐1 (0.5 gallons per ton) of formic acid. The resulting silage had a dry matter digestibility of 72.9% and was fed ad libitum with 3.8 kg (8.4 lb) concentrates as a supplement. A medium‐quality grass silage, of lower digestibility and dry matter content (70.0 and 25.4% respectively), was also fed ad libitum in addition to either 3.8, 5.7 or 7.6 kg (8.4, 12.5 or 16.7 lb) concentrates. The feeding treatments were commenced immediately after calving and were terminated on 9 April giving a mean period of 72 d on the treatments. Over the experimental period the animals on the high‐quality silage consumed 15% more silage dry matter and produced 8% more milk that those on the medium‐quality silage with the same level of concentrate supplementation. From the results it was estimated that 1.9 kg (4.3 lb) of additional concentrates would be required with the medium‐quality silage to give an equivalent milk output to that achieved with the high‐quality silage. Milk composition, liveweight change, ration digestibility and nitrogen balance data are also presented.
Maize silage with a non‐protein nitrogen additive as feed for autumn‐calving cows
Authors: PHIPPS R.H. , CRAMP D.G.
Published: April 2006

Maize silages made in October were fed to forty‐three autumn‐calving cows during a 20‐week winter feeding trial. The control silage received no additive whereas a non‐protein nitrogen (NPN) additive was applied to the other silage at harvest time. The four experimental feeding treatments were: A, maize silage + 6 kg d−1 barley; B, maize silage with NPN + 6 kg d−1 barley; C, maize silage + 5 kg d−1’barley + 1 kg d−1 extracted decorticated groundnut cake; D, maize silage with NPN. The mean daily milk yields of cows on the treatments were 14.7, 15.1, 15.3 and 15.0 kg respectively. All cows received maize silage ad libitum. There were no significant differences in milk yield but the milk produced by the cows on treatment D had significantly lower concentrations of milk fat, protein and solids‐not‐fat when compared to the other three treatments. The cows on treatment D had a negative liveweight change which was significantly different (P < 0.05) from those of the cows on treatments B and C.
Dalapon resistance at an early seedling stage in Lolium perenne
Authors: THORNTON M. S. , CHARLES A. H.
Published: April 2006

The inhibitory effect of the herbicide dalapon on germination and shoot elongation was evaluated in two perennial ryegrass cultivars, Melino RvP and Cropper. These cultivars had been shown to be dalapon resistant and susceptible, respectively, in a previous comparison of 14‐week‐old plants.

Dalapon (10‐2 and 10‐3 m) significantly reduced rates of germination and shoot elongation to the same extent in both cultivars.

It is suggested that the effects of dalapon on germination and shoot elongation during the first 9 days of development are not indicative of levels of resistance in more mature plants.
The effect of partial neutralization of formic acid silages with sodium bicarbonate on their volimtary intake by cattle and sheep
Authors: FARHAN S. M. A. , THOMAS P. C.
Published: April 2006

In two 4 × 4 Latin Square experiments, one with dry cows and one with sheep, animals were given ad libitum early‐cut ryegrass silages prepared using formic acid (2.31 t−1) as an additive. The silages were offered either untreated or partially neutralized with either a low (8 g kg−1 fresh weight) or high (16 g kg−1) level of sodium bicarbonate or with sodium bicarbonate solution (50 g kg−1) given as an intraruminal infusion at a rate sufficient to provide bicarbonate at a rate similar to that provided by the high level of dietary addition.

In cows the bicarbonate treatments were associated with a depression in the intake of organic matter which at the high level of addition of bicarbonate was statistically significant (P < 0.05). In sheep the bicarbonate treatments were associated with a slight increase in the intake of organic matter but the efFects were non‐significant (P > 0.05). In both species water intake increased directly with the quantity of bicarbonate ingested.

In both experiments the bicarbonate treatments increased rumen pH but there were no significant treatment effects on the concentration of ammonia or of total or individual short‐chain fatty acids in the rumen fluid. In sheep, bicarbonate addition or infusion had no effect on the digestibility of organic matter but at the high levels of bicarbonate supplementation there was a tendency for the digestibility of nitrogen to be depressed.

In two further experiments each with two dry cows determinations were made of the effects on food intake of (a) the insertion of water‐filled bags into the rumen and (b) the removal of digesta from the rumen. Treatment (a) produced consistent and significant (P < 0.05) depressions in dry matter intake and treatment (b) increased (P < 0.05) dry matter intake in one cow but not in the other.

The lack of significant improvement in silage intake through the addition of sodium bicarbonate to the diet indicated that the acidity of the silage was not a major factor limiting appetite. On the other hand, the effects of the insertion of water‐filled bags into the rumen and of the removal of digesta from the rumen on feed intake were consistent with appetite being controlled through a rumen‐fill mechanism.
A mathematical model to study forage conservation methods
Authors: PARKE D. , DUMONT A. G. , BOYCE D. S.
Published: April 2006

A mathematical model which simulates a single‐cut forage conservation system is described. It was designed to investigate the effect of machine performance on the nutrient content of conserved forage but its scope is much wider, so that the effects of such aspects as crop growth characteristics, climatic differences and management policy can be assessed. An example of the use of the model to determine the value of chemical additives to high moisture content hay is described in detail. Various uses of the model are discussed and some of its limitations are shown to be caused by a lack of data on factors determining dry matter losses.
Competition between Lolium perenne and Poa trivialis during establishment
Authors: HAGGAR R. J.
Published: April 2006

Three experiments were carried out in boxes to determine the response of L. perenne seedlings to competition from P. trivialis seedlings at different densities and ages and when the proportions of the two species were varied according to the replacement principle. Tiller numbers per plant were significantly reduced by P. trivialis at densities commonly found in the field. Prior establishment of P. trivialis caused disproportionate damage to L perenne tillering and the early removal of such plants resulted in yield benefits to L. perenne. When sown together, P. trivialis was shown to be competitive towards L. perenne during the first 4 weeks of establishment but during the next 4 weeks, although competition was still occurring between the two species to the detriment of Poa, relative productivity (but not total productivity) was marginally greater in the mixture. The need for early herbicide treatment to prevent interspecific competition between graminaceous species during establishment is discussed.
Winter hardiness in Lolium multiflorum Lam. III. Selection for improved cold tolerance and its effect on agronomic performance
Authors: HIDES D. H.
Published: April 2006

Nine varieties of Italian ryegrass were subjected to two generations of selection for cold tolerance using a controlled environment test. Selection led to a significant overall improvement in average tiller survival from 39·8 to 47·7%, even though the selection intensity achieved was not more than 20%. Although individual varieties varied in initial tolerance from 31·1 to 71·4%, the cold room tests were not sufficiently sensitive to attach significance to differences in response to selection which varied from 0·3 to 17·6%. Agronomic assessment of spaced plants indicated that the winter and spring growth potential of all nine varieties was unaffected by selection for cold tolerance. Although some of the selected populations showed a significant decline in their total yields and persistency, others showed no significant change in these characteristics. The plant breeding implications of these results are discussed.
The digestibility of diets containing processed dried lucerne by sheep and cows
Authors: THOMAS S. , CAMPLING R. C.
Published: April 2006

A series of trials was conducted to compare the digestibility of organic matter in castrated male sheep and non‐lactating and lactating cows given diets containing lucerne cobs. Similar digestibility coefficients were determined when sheep and non‐lactating cows were given hay and lucerne cobs, but lactating cows digested diets of hay, lucerne cobs and concentrates less well than sheep. It is concluded that if sheep are used in digestibility trials with diets containing processed lucerne and concentrates intended for milking cows, appreciable errors of prediction of digestibility of organic matter may arise.
The effect of controlling bracken [Pteridium aquilinum (L.) Kuhn] on pasture production
Authors: Davies G. E. , NEWBOULD P. , BAILLIE G. J.
Published: April 2006

The outcome of spraying two bracken‐infested hill sites in July with asulam at the commercial rate of 4·5 kg a.i. per ha was a 98% reduction in frond numbers which persisted for the following 3 years. Broad‐leaved grasses, Agrostis tenuis, Agrostis canina and Poa pratensis, were susceptible to asulam and were severely reduced at both sites while fine‐leaved grasses, Festuca ovina and Deschampsia flexuosa, were resistant. Over a period of 3 years after spray application the original bare ground under the bracken canopy and that produced by the effects of asulam was recolonized by the recovery of the broad‐leaved grasses and an increase in the cover of herbs. The latter also increased on the unsprayed control areas.

A favourable aspect and an abundance of the productive broad‐leaved grasses appeared to be the main factors which determined the amount of increase in herbage yield observed following spray treatment. One such area gave a herbage DM yield of 3039 kg ha‐1 during the growing season which was 47% greater than the control while an area with a less favourable aspect and dominated by the less productive fine‐leaved grasses gave a herbage yield of 2069 kg ha‐1 which was only 18% greater than the control.
Improvements to the dry‐weight‐rank method for measuring botanical composition
Authors: JONES R. M. , HARGREAVES J. N. G.
Published: April 2006

Two modifications have been made to the dry‐weight‐rank (DWR) method for measuring botanical composition. One previous limitation of the method has been that it gives biased results in pastures where there is a consistent relation between quadrat dry matter yield and the order in which species are ranked for yield. A weighting factor, applied to the DWR multipliers and based on pasture yield in quadrats estimated for dry weight rank, can correct for this bias. In routine pasture sampling quadrat yields are often visually estimated in the same quadrats in which composition is assessed by DWR. These estimated quadrat yields can then be used as weighting factors to improve the accuracy of DWR as well as to estimate pasture yield. Dry weight rank has also been unsuited to pastures which are heavily dominated by one species but this problem can be lessened by assigning more than one rank to the dominant species, a method referred to as ‘cumulative ranking’.

Both these modifications were found to give a more accurate estimate of composition using data from a wide range of tropical and temperate pastures. On the other hand, creation of new DWR multipliers for particular cases was inadvisable. All data made available for this study and the original data ('t Mannetje and Haydock, 1963) were used to derive new multipliers: 0·705, 0·238 and 0·057. The overall benefits from using the new multipliers will, however, only be slight.
Herbage intake and milk production by grazing dairy cows 1. The effects of variation in herbage mass and daily herbage allowance in a short‐term trial
Authors: COMBELLAS J. , HODGSON J.
Published: April 2006

Twenty‐four British Friesian cows were allocated between six grazing treatments (two levels of herbage mass x three levels of daily herbage allowance) in a balanced change‐over design with four periods of 12 d each at monthly intervals. Herbage OM mass ranged from 3790 to 5770 kg ha‐1 measured to ground level and daily herbage DM allowances were 30, 60 and 90 g per kg animal live weight. Herbage OM intake was lower at high than at low herbage mass (24·6 vs 26·3 g per kg LW), and was 26·9, 26·6 and 22·9 g per kg LW respectively at daily herbage DM allowances of 90, 60 and 30 g per kg LW. Milk yield was not affected by herbage mass but was depressed at the low herbage allowance.
Nitrogen studies in Lolium perenne grown for seed III. The effect of nitrogen and water stress
Authors: HEBBLETHWAITE P. D. , McLAREN J. S.
Published: April 2006

The effects of water and nitrogen (N) availabilities and their possible interactions on the seed yield and yield components of S23 perennial ryegrass grown in pots in the glasshouse were investigated. Increasing the N fertilizer from 0 to 5 g per pot more than doubled the seed yield but no further increase in seed yield was found by increasing N fertilizer from 5 to 10 g per pot. The main effect of increasing water availability was to increase both seed and straw yield. When N had been applied, accumulated evapotranspiration was linearly related to seed and straw yield. The component of yield having the greatest effect on yield was the number of fertile tillers and, although both N and water availability affected this component, N had the larger effect. Implications of these responses are discussed in relation to the potential yield of the crop and to the field situation.
Herbage intake and milk production by grazing dairy cows 2. The effects of level of winter feeding and daily herbage allowance
Authors: LE DU Y. L. P. , COMBELLAS J. , HODGSON J. , BAKER R. D.
Published: April 2006

Two experiments are described in which two levels of winter feeding and three levels of herbage allowance during the grazing season were imposed upon March/April calving British Friesian dairy cows. The winter treatments resulted in differences in live weight and milk yield at turnout of 35 and 53 kg and 3·4 and 3·2 kg d‐1 for the two trials. Subsequently, when grazed at generous herbage allowances, the cows were able to compensate for much of this difference but when herbage was restricted the milk yield differences were accentuated.

Groups of cows from each winter treatment were offered 25, 50 or 75 (Experiment 1) and 30, 50 or 70 (Experiment 2) g herbage DM per kg LW daily during the grazing season. Daily herbage intakes on the three allowances in each trial were 14·1, 13·3, 10·7 and 12·5, 12·1, 11·5 kg OM and milk yields were 16·0, 15·3, 12·5 and 15·2, 14·3, 11·8 kg SCM respectively. Both intake and milk production were depressed once the cows were forced to consume more than 50% of herbage on offer or to graze the sward down to a mean height of less than 8–10 cm. Grazing behaviour observations indicated that under rotational managements the cows did not compensate for restrictions in available herbage by grazing longer. Highest levels of milk production per unit area were observed in both trials when production per cow was depressed by 20–25%.
Herbage measurement in situ by electronics. 1. The multiple‐probe‐type capacitance meter: a brief review
Authors: ANGELONE ALFONSO , TOLEDO JOSE M. , BURNS J C.
Published: April 2006

The history and development of the multiple‐probe capacitance meter used for in situ, non‐destructive estimations of herbage mass is reviewed. An elementary, semi‐theoretical electric‐field analysis focuses attention on the inherent difficulties associated with the multiple‐probe approach. This report establishes the background for the introduction of an ‘earth‐plate’ capacitancemeter.
The influence of sowing date, harvest date and seed rate on the yield of forage peas
Authors: POTTS MICHAEL J.
Published: April 2006

A series of preliminary trials is described to assess the potential and some of the cultural requirements of new cultivars of forage peas grown as pure stands in the west of Scotland. Optimum sowing date was late March for harvesting 15 weeks later to leave sufficient of the growing season for a catch crop or the establishment of a grass sward. Yield of dry matter (DM) at harvest was approximately 6 t ha‐1 but DM concentration varied greatly with season. The digestibility of the organic matter was of the order of 0·700 and the crude protein concentration in the DM 170 g kg‐1. DM yield increased with increasing seed rate up to 200 kg ha‐1 the maximum rate tested.
Growth and carbon economy of nodulated white clover in the presence and absence of combined nitrogen
Authors: HAYSTEAD A. , KING J. , LAMB W. I. C. , MARRIOTT C.
Published: April 2006

An investigation of the carbon economy of single S184 white clover plants nodulated with an effective strain of Rhizobium trifolii growing on N‐free nutrient solution and supplied with 150 parts/106 N as NH4NO3 has shown that 10% more of the C fixed per day is available for growth in the plants supplied with combined N. The difference between the two groups of plants is a result of higher respiratory activity in the roots of plants growing exclusively on N2. In terms of shoot growth, however, the difference in growth rate is likely to be less than 10%, because the rate of root growth is greater in the plants supplied with a moderate level of combined N. There is no evidence that NO‐3 and CO2 compete for photosynthetically produced reductant in the leaves of plants grown on N2+NH4NO3, since no reduction in net photosynthesis was observed in plants assimilating combined N.

An experiment carried out on detached leaflets of white clover grown on N2 and on N2+ NH4NO3 has shown that NO‐3 ‐reducing activity is present in the leaflets of plants grown on N2+ NH4NO3 but not in plants grown on N2 and that the activity is light‐dependent. Measurements of 14CO2 respired in the light and dark by leaflets previously allowed to photosynthesize 14CO2 showed that the ratio of 14CO2 output in the light to 14CO2 output in the dark was no higher in plants grown on N2+ NH4NO3 than in plants grown on N2. This observation is consistent with the finding that N source does not affect net photosynthesis in whole plants.
Influence of initial cutting date and cutting frequency on yield and quality of star, elephant and Guinea grasses
Authors: OMALIKO C. P. E.
Published: April 2006

Two experiments were conducted to estimate the influence of initial cutting dates in March and April and of cutting frequencies on Guinea grass, elephant grass and star grass productivity. Increasing delay in date of first cut in the season resulted in a progressive increase in dry‐matter yield. 72–81% of the tiller population at any cut were vegetative and this helped to maintain good aftermath yield for each date of first cut. Early April cuts gave the highest dry‐matter yield and early March the least.

Harvesting frequencies affected the sward productivity such that the annual dry matter yield increased with increasing harvesting interval from 6800 kg ha‐1 for a 3‐week interval to 13,000 kg ha‐1 for a 10‐week interval. The proportion of green leaf in the dry matter dropped from 57·7% at 3‐week intervals to 32·0% at 10‐week intervals. Seasonal effects showed that potential yield was reduced by a short interval between harvests early in the season but not late in the season. Species differences in quality and in the harvesting interval that gave the maximum yields were noted. These results are discussed in relation to management of the sward throughout the growing season.
A comparison of root competition and shoot competition between Dactylis glomerata and Holcus lanatus
Authors: REMISON S. U. , SNAYDON R. W.
Published: April 2006

Dactylis glomerata and Holcus lanatus were grown together in boxes with either full competition, root competition only, shoot competition only or no competition between them. The boxes were either fertilized (150 kg ha‐1N, 100 kg ha‐1 K, 80 kg ha‐1 P) or not fertilized. The experiment was continued for 13 months, and a total of six cuts were taken.

H. lanatus was more competitive than D. glomerata throughout the experiment, though the effect declined after flowering during the second growing season. The effects of root competition were generally much greater than those of shoot competition and tended to increase during the first year. However, the effects of root competition declined, relative to shoot competition, after flowering in the second growing season.

Fertilizer applications slightly increased the root competitive ability of H. lanatus relative to D. glomerata but slightly reduced its shoot competitive ability.
The effect of companion perennial ryegrass cultivars on red clover productivity when timing of the first cut is varied
Authors: LAIDLAW A. S. , McBRATNEY JUNE M.
Published: April 2006

Replicated plots of Hungaropoly red clover were sown on a sterilized area in May 1975 alone (seed rate 11 kg ha‐1) or with one of six cultivars of perennial ryegrass (seed rate 3·5 kg ha‐1) viz. Cropper and S24 (early heading), Barlenna and Hora (medium heading) and Melle and Perma (late heading). In 1976 and 1977 primary growth was cut at one of four dates ranging from mid‐May to mid‐June and thereafter plots were harvested twice each year.

Varying the time of first cut did not have a significant effect on total dry matter (DM) yield in either year despite differences in means of cutting treatments on annual red clover yields of the order of 6–9%.

In some companion grass treatments total DM yield in 1976 was increased and total red clover yield and percentage red clover contribution were reduced relative to swards sown only with red clover. In 1977 a similar but non‐significant trend was found. Swards containing early ryegrasses had higher total herbage DM yields but lower red clover yields and contents than all other swards at the first harvest in both years.

Delay in date of taking the first harvest in 1976 reduced DM digestibility in the first cut and increased it in the second in both years.

It is suggested that by cutting early and increasing the number of harvests from three to four per year, differences in the content of red clover between the first and second cut might be reduced, and it is concluded that more benefit is derived from red clover when medium or late heading ryegrasses are used as companion grasses.
The interaction of perennial ryegrass and timothy in mixtures and their reaction to clover and nitrogen in cut swards
Authors: CHESTNUTT D. M. B. , BARTHOLOMEW P. W. , BINNIE R. C.
Published: April 2006

Results of experiments where timothy, perennial ryegrass and mixtures of these two in the presence and absence of white clover and receiving various nitrogen treatments were compared, have been considered in the light of previous related experiments. There is evidence that under certain conditions greater yields of sown grass can be achieved from mixed seedings than from either of the two grasses on its own. No yield advantage was gained from mixtures of species when cut infrequently after a late first cut. Inclusion of white clover changed the balance of species in favour of perennial ryegrass and no yield advantage occurred with mixtures in the presence of clover. Yield advantage may be related to seasonal changes in the order of dominance of the two grass species in mixed seedings.
Initial evaluation of lupin for forage
Authors: SHELDRICK R. D. , TAYLER R. S. , MAINGU Z. , PONGKAO S.
Published: April 2006

Small‐plot trials with Lupinus albus cv. Kievskij Mutant (sweet) and L. angustifolius cv. Kubesa (bitter) and Uniwhite (sweet) were sown in April 1977. Sequential whole‐crop samples of the above ground dry matter (DM) were taken to assess the interaction of DM yield and forage quality during crop growth. Both species had similar DM yields, exceeding 11 t DM ha1 in August. L. albus displayed superior whole‐crop in vitro digestibility from late July, due to the large contribution to total DM yield from this time from its succulent, highly digestible pod shells. L. angustifolius showed higher N contents in June and early July, but N concentrations fell below those of L. albus from early August. The steady decline in digestibility of forage from L. angustifolius suggests this species should be harvested rather earlier than L. albus. Harvested in mid‐August, L. albus should yield 11 t DM ha‐1, ata D‐value of 64 and 23·5 g N per kg DM, whereas L. angustifolius harvested 10–14 d earlier should give the same DM yield, but at a D‐value of 58 and 22·0 g N per kg DM. Lupins can thus be regarded as having good potential forage yields, but providing material of only moderate quality.
Silage and milk production: a comparison between grass silages of different chop lengths and digestibilities
Authors: CASTLE M. E. , GILL M. S. , WATSON J. N.
Published: April 2006

Four grass silages of two chop lengths and two D‐values were made from S23 perennial ryegrass, and compared in a feeding experiment with lactating cows and in an eating‐behaviour study with non‐lactating cows. The median chop lengths were 11·6 and 11·5 mm in the short silages and 18·2 and 19·5 mm in the medium silages. Chop length had negligible effects on D‐value and on pH with values of 3·81 and 3·94 on the short and medium silages respectively.

Silage DM intakes were higher on the short than on the medium‐chop silages in both experiments except where the high D‐value silage was supplemented with concentrates. Milk yields were not affected significantly by chop length with daily values of 19·3 and 19·7 kg per cow on the short and medium treatments respectively with the high D‐value silage, and 18·2 and 18·3 kg per cow with the low D‐value silage. Chop length had only small and non‐significant effects on milk composition.

Eating times expressed as min per kg DM were significantly lower on the short than on the medium‐chop silages.

It is concluded that the small differences between the short‐ and the medium‐chop silages were of no economic importance.
Silage and milk production: a comparison between long, chopped and ground hays as supplements to silage of high digestibility
Authors: CASTLE M. E. , GILL M. S. , WATSON J. N.
Published: April 2006

Grass silage made in May from S24 perennial ryegrass had a DM concentration of 262 g kg‐1 and an in vitro D‐value of 0·698, and was given ad libitum to twelve Ayrshire cows in a 16‐week feeding experiment. In addition supplements of hay with a mean in vitro D‐value of 0·603 were offered in one of three forms—long, chopped (12·1 mm) or ground (0·80 modulus of fineness) and cubed—and of concentrates given at either 2 or 4 kg per 10 kg milk. Hay averaged 18·2% of total forage DM intake with mean daily intakes of 1·28, 1·22 and 2·26 kg DM per cow in the long, short and ground forms respectively. The highest daily intakes of forage, i.e. silage plus hay, occurred on the ground hay treatments, with values of 10·24 and 9·25 kg DM per cow on the 2 and 4 kg concentrate treatments respectively. The mean daily milk yields were 18·2,18·2 and 19·2 kg per cow on the long, short and ground hay treatments respectively but the increase in yield with the ground hay was only significant at the low level of concentrate intake. The hay treatments had small and non‐significant effects on milk composition. It is concluded that ground hay was superior to either long or chopped hay as a supplement for silage, but the small advantages depended on the level of concentrate intake.
The influence of light and temperature during winter on growth and death in simulated swards of Lolium perenne
Authors: THOMAS HENRY , NORRIS IAN B.
Published: April 2006

Two growth experiments were carried out in January‐March 1978 in which simulated swards of perennial ryegrass were (1) heated by soil warming cables to give soil surface temperatures of approx. 7·5‐9·C above ambient temperature, (2) shaded with netting to reduce light levels by approx. 50%, or (3) both heated and shaded.

Heating alone increased leaf appearance, death, extension, lamina size, leaf area index (LAI), tillering (month 1)and whole plant weight (month 2) and reduced stubble water‐soluble carbohydrates and specific leaf weight (SLW).

Shading alone increased leaf extension, lamina size and LAI but to a lesser extent than did heating. Shading decreased SLW, leaf death rate, tillering (month 2), stubble carbohydrates and whole plant weight, but not herbage weight.

The effects of heating plus shading were similar to those of heating alone, except that the increases in leaf size, extension and LAI were even greater, and shoot bases and roots had low or negative growth rates.

In general the heating treatments caused a rapid turnover of leaf material, but net herbage growth was relatively insensitive. It is concluded that (1) temperature rather than light was limiting whole plant growth, especially from mid‐February to mid‐March and (2) mild, dull weather in winter is likely to induce tiller death associated with reduced investment in carbohydrate reserves.
Effect of defoliation on flower initiation in white clover in summer
Authors: THOMAS R. G.
Published: April 2006

Flowering behaviour of plants of six cultivars of Trifolium repens (Kent Wild White, Grasslands Huia, S100, Blanca, Olwen and Milkanova) growing in field plots at the Grassland Research Institute, Hurley, was recorded in mid‐July. Half of each plot had been defoliated in early May, the other half in mid‐June. In all cultivars defoliated in May, inflorescence initiation had stopped even though the natural photoperiod at that time was well above the critical daylength for initiation Defoliation in mid‐June had led to a renewal of inflorescence initiation in all cultivars.

The results confirm that the stimulatory effect of defoliation on inflorescence initiation in plants that have stopped initiation in long days, which has previously been observed in Grasslands Huia in controlled environments, also occurs in the field and in other cultivars.
Cattle slurry as a source of nutrients for red clover: herbage production and clover contribution
Authors: GRACEY H. I.
Published: April 2006

An established sward of red clover cv. Hungaropoly sown pure received approx. 30 kg P ha‐1 and 200 kg K ha‐1 each year for 3 successive years. The P and K were applied either as cattle slurry, inorganic fertilizer or combinations of these. Treatments were applied either in spring or after the first harvest. There were a total of six treatments and these were harvested three times each year. The average yields of total herbage DM over all the treatments in the first, second and third years were 15·2, 14·2 and 14·2 t ha‐1 respectively and the various treatments had no significant effect on the overall yields.

Treatments had a significnt effect on red clover DM yields and percentage red clover in one harvest in each of the first 2 years and all three in the third year. Yields of red clover were lower and grass higher in treatments receiving cattle slurry only. On this treatment there was a total yield of 23·2 t ha‐1 red clover DM in the 3 years compared with 30·2 t ha‐1 on the inorganic fertilizer treatments. However, by applying P and K fertilizer in the spring, followed by cattle slurry after the first harvest, it was possible to maintain a high proportion of red clover in the sward and to produce yields of red clover DM similar to those on the inorganic fertilizer treatments.
A comparison of a hybrid stubble turnip (cv. Appin) with other cruciferous catch crops for lamb fattening. 2. Animal performance and toxicological evaluation
Authors: YOUNG N. E. , AUSTIN A. R. , ORR R. J. , NEWTON J. E. , TAYLOR R. J.
Published: April 2006

Forage brassica catch crops can provide a valuable source of additional feed in the autumn when supplies of other feed are limited. Weaned lambs grazed either (A) a novel hybrid crop, stubble turnip cv. Appin, or (B) a sequence of crops consisting of fodder radish cv. Nerys, followed by forage rape cv. Canard. Forty, 60 or 80 g of crop DM per kg current live weight (LW) were allowed daily and the performance, intake and carcass yield of the lambs were monitored. Lamb LW gains were lower on treatment A (45, 65 and 72 g d‐1) than on B (78, 111 and 117 g d‐1) at the 40‐, 60‐ and 80‐g DM d‐1 allowances respectively. Intakes of forage crops, however, did not differ significantly, probably because the estimates of intake were made in the middle of each 14‐d allocation period of the crops. The intake values are thus an indication of the potential intake when a relatively plentiful supply of food is available; they were 19·2, 17·2 and 18·2 g OM kg‐1 LW for treatment A and 16·2, 19·2 and 19·2 g OM kg‐1 LW treatment B at the 40‐, 60‐ and 80‐g DM d‐1 allowances respectively.

Mild anaemia occurred in lambs feeding on both crops. Anaemia was more marked on treatment B, which was consistent with the higher concentrations of S‐methyl cysteine sulphoxide (SMCO) but as the performance of animals was superior on treatment B, SMCO intake and anaemia are not thought to be the first or the most important factors in limiting animal performance. Goitrogenic changes in thyroid glands occurred on both crops. Mean weights of paired thyroid glands were 3·22, 4·28 and 4·21 g on treatment A and 3·29, 5·27 and 5·21 g on B at the 40‐, 60‐ and 80‐g DM d‐1 allowances respectively; the effects of both treatment and allowance were significant (P <0·21). Thiocyanate concentrations were higher on treatment A than B, indicating differing glucosinolate concentrations. While this was consistent with animal performance, it was not consistent with the weight of thyroid glands. However, the goitrogenic responses may have been complicated by the ingestion of soil iodine because very high faecal ash values were recorded. Thus, glucosinolates appear not to have affected lamb growth rate by their goitrogenic effect but the possibility remains that they may have influenced performance by other means.
Slot‐seeding investigations. 1. Effect of level of nitrogen fertilizer and row spacing on establishment, herbage growth and quality of perennial ryegrass
Authors: HAGGAR R. J. , SQUIRES N. R. W.
Published: April 2006

Three field experiments showed that perennial ryegrass can be successfully slot‐seeded into an existing Festuca‐Agrostis sward. Ryegrass survival was satisfactory in all cases but was improved on a low fertility site by the application of fertilizer N, P and K in the slot at sowing.

The effect of varying inter‐row spacing from 37·2 to 15 cm was measured in a 3‐year experiment. In year one, involving seven cuts, slot‐seeding increased total herbage dry matter harvested by a mean value of 17%; inter‐row distances of 22·2‐30 cm gave the optimal combination of ryegrass + old sward herbage. Differences in yield between inter‐row spacings declined in the subsequent two years, as the rows of ryegrass thickened. Ryegrass digestibility (measured only in year two, from six cuts) was higher than that of the old sward; total metabolizable energy harvested from 15‐cm rows was 20% higher than that from unsown controls. Increasing N input from 200 to 400 kg ha‐1, starting in year two, only produced a significant increase in total herbage harvested in year three but proved effective in increasing the ryegrass contribution from the wider spaced rows.
The management of Brassica for winter forage in the sub‐tropics
Authors: KALMBACHER R. S. , EVERETT P. H. , MARTIN F. G. , JUNG G. A.
Published: April 2006

In subtropical latitudes temperate crops can be grown during the cool months but the growing season is restricted by the termination and beginning of hot weather. Postponing sowing date in south Florida from October to November to January resulted in 150, 130 and 110‐d growing seasons respectively. Dry matter (DM) yields of turnip, swede, rape and kale were lowered by each later sowing date and shorter growing season, and crude protein (CP) concentration was the same as for, or was increased by late sowing. In vitro organic matter digestibility (IVOMD) of turnip, swede and rape leaves was not affected by sowing date, but roots of turnip and swede from the earlier sowings and longer growing seasons were more digestible. Yield of the four species depended on harvest management as well as date of sowing and length of growing season. Total yield of turnip and swede were unaffected by harvest management but multiple cutting resulted in greater leaf yields and smaller root yields, whereas stockpiling resulted in smaller leaf yields and larger root yields. Kale produced more DM when harvested once at the end of the winter growing season but rape produced the greatest DM yield when sown in October and harvested
Leaf surface expansion on the main axes of white and red clovers
Authors: ARNOTT R. A. , RYLE G. J. A.
Published: April 2006

Plants of white clover (Trifolium repens L.) cv. Blanca and red clover (T. pratense L.) cv. Hungaropoly were grown singly in controlled environments. The effects of eight treatments on the two species were examined: 16‐ and 8‐h photo‐periods × 20/15 and 15/10°C day/night temperatures ×Rhizobium‐free plants receiving nitrate N and inoculated plants receiving no combined N. Twice weekly measurements of the main axis leaf size, petiole length, rate of leaf production and the time period between the appearance of a leaf and its final size were carried out for 8 weeks after sowing.

Increasing the day/night temperature from 15/10 to 20/15°C, or doubling the daylength from 8 to 16 h (doubling the daylength increased temperature by 1·2°C) accelerated the rate of leaf production and expansion and increased petiole length and the final area of leaves. Most aspects of main axis leaf growth were reduced in the inoculated plants dependent on their own N fixation compared with the nodule‐free plants receiving abundant nitrate N. The results suggest that the temperature above which white clover exhibits appreciable leaf growth in the field could be relatively high compared with grasses. Further research is required to define these differences and relate them to seasonal changes in the environment.
Frequency and severity of defoliation of grass and clover by sheep at different stocking rates
Authors: CURLL M. L. , WILKINS R. J.
Published: April 2006

The frequency and severity of defoliation of individual grass tillers and clover plant units was studied in Lolium perenne‐Trifolium repens swards grazed by sheep at stocking rates ranging from 25 to 55 sheep ha‐1 and either receiving no N fertilizer or 200 kg N ha‐1. On average, sheep at the highest stocking rate defoliated individual tillers once every 4·2 d compared with once every 9·2 d at the lowest stocking rate with the removal of 58% and 47% of the leaf length of each tiller leaf at these stocking rates. Clover plant units were defoliated once every 4·2 d at the highest stocking rate and once every 7·2 d at the lowest stocking rate with the removal of 51% of its leaves and 12% of its stolon at the high stocking rate and 42% and 4% respectively at the low stocking rate. Differences in frequency and severity of defoliation between N fertilizer treatments were smaller than between stocking rates. Grass tillers and clover plant units were both defoliated less frequently and less severely in swards fertilized with N, though the difference in defoliation frequency between fertilizer treatments decreased as stocking rate increased. Defoliation frequency was related to the length of grass leaf per tiller or number of clover leaves per plant unit, and to the number of these tillers and the herbage on offer.
A survey of ryegrass swards for the presence of fungal pathogens in relation to management
Authors: LAM ANNIE
Published: April 2006

Surveys of perennial and Italian ryegrass swards (Lolium perenne L. and L. multiflorum Lam.) at regular intervals in 1977 and 1978 in Berkshire, Wales and Devon confirmed that leaf infection by Drechslera spp. was the most frequently occurring foliar fungal disease. Rhynchosporium spp. and Puccinia coronata Corda were also recorded but in contrast to Drechslera spp., which caused damage throughout the year, attacks by these two fungi were only sporadic.

The incidence of Drechslera was greater in 1977 than in 1978 and was greater in Berkshire where most fields were infected in both years than in Wales and Devon. Both perennial and Italian ryegrasses were infected. The number of leaves damaged increased with leaf age. Damage was greater on fields managed for conservation than those which were grazed. Infection increased from February onwards and was greatest in autumn. It is concluded that Drechslera might be controlled by removing infected herbage in autumn by cutting.

Rhynchosporium spp. were prevalent only in Berkshire and more Italian ryegrass fields (ca, 50%) were infected than perennial ryegrass fields (ca, 10%). Infection was confined to the period March to May. This pathogen caused more leaf area damage than Drechslera.

Puccinia coronata occurred only once in Devon and Wales. In Berkshire incidence was confined to 1978 and was common from September to November, when 60–70% of both Italian and perennial ryegrass fields were infected. Some difference between perennial ryegrass cultivars was observed.
The effects of Rumex obtusifolius on the seasonal yield of two mainly perennial ryegrass swards
Authors: OSWALD A. K. , HAGGAR R. J.
Published: April 2006

A preliminary field experiment on a sward cut six times during 1978 indicated that total grass herbage harvested was negatively related to the number of Rumex obtusifolius plants present; densities of five to ten plants m−2 resulted in reductions of up to 30%, although the total quantity of herbage harvested (including Rumex) may have remained constant. However, R. obtusifolius densities did not significantly affect grass yield during the first half of the growing season. A negative relationship between R. obtusifolius ground cover and grass yield, particularly from late July onwards, was shown in a second field experiment during 1979 and 1980 using a 3‐cut management. It was estimated that to produce a 20% reduction in grass growth in July‐August and October, R. obtusifolius ground covers of 30% and 20% respectively were needed. Sixty per cent of the total herbage harvested in 1980 consisted of R. obtusifolius. These results indicate the damage that can be caused by this species and suggest that control measures should be taken before early summer.