bluuebunny/crossref_metadata_2025_split huggingface dataset:
An integrated methodology for studying short‐term grazing behaviour of cattle
Authors: LACA E. A. , UNGAR E. D. , SELIGMAN N. G. , RAMEY M. R. , DEMMENT M. W. 
Published: April 2006

AbstractGrazing studies are hampered by difficulty in controlling the characteristics of that part of the sward encountered by animals. A methodology was developed to study the effects of sward height, density and spatial arrangement on bite dimensions, bite weight and instantaneous intake rate by cattle. Hand‐constructed swards (HCS) consisted of tillers threaded through wooden modules and attached to a base board. The microphone of a cordless transmitter was attached to the forehead of steers before swards were grazed. HCS were bolted onto a force plate which recorded the forces exerted during grazing. Grazing sessions were videotaped. Height and density of swards were successfully controlled by hand‐construction. Bite weight was determined more accurately by dry matter (DM) disappearance than by the reduction of fresh weight corrected for moisture loss and herbage DM content. Bite area and bite depth were precisely measured by counting and measuring the residual height of grazed plant parts. Bites and chews were identified and counted from the soundtrack of video tapes. Visual count of chews was inaccurate because animals can prehend new herbage and chew herbage previously gathered with the same jaw movement. Many jaw movements involve only manipulation of herbage without biting or chewing. Bite dimensions result from the physical interaction of relatively fixed motor patterns, such as tongue sweeps, with vegetation structure. Thus, bite dimensions measured by this technique are relevant to field situations.
The role of the legume in the nitrogen cycle of productive and sustainable pastures
Authors: THOMAS R. J. 
Published: April 2006

AbstractThe role of the legume in the nitrogen (N) cycle was examined in grazed pastures receiving no N fertilizer of both temperate and tropical regions by simulating the fluxes of N through different processes of the cycle. The amounts of legume‐fixed N required to balance the cycle without invoking a drain on soil organic N reserves (i.e. no net N mineralization) was estimated to vary from 38 to 53% of the above‐ground herbage N or from 20 to 31% on a dry matter (DM) basis for tropical pasture systems with a range of pasture utilization of 10–40%. At higher pasture utilization levels of 50‐70%, more typical of intensively grazed temperate pastures, the N input requirement in the absence of fertilizer N would be 57‐67% of the aboveground herbage N or 35‐45% DM. An examination of the role of each contributory process of recycling (viz. excreta returns, internal cycling or remobilization from senescing tissues, litter decomposition) suggests that variations in the amounts of internally cycled N would have the greatest impact on the requirement for biologically fixed N at low levels of pasture utilization (10‐40%), while at high pasture utilization levels of 70%, variations in the recovery of excreta‐N would have a major effect on the requirement for fixed‐N to balance the cycle.The amounts of biologically fixed N required to sustain a range of herbage DM yields of 3‐22 t DM ha −1 yr−1 would range from 15 to 158 kg N ha−1 yr−1 for tropical pastures. For intensively managed temperate pastures producing 6‐15 t DM ha−1 yr−1 with a N content of 3·5%, a range of fixation of 120‐352 kg N ha−1 yr−1 is required. These simulations indicate how legume contents of 20‐45% of herbage DM could contribute to productive and sustainable (in terms of N) pasture systems of both temperate and tropical regions
The potential transmission of clover rot, Sclerotinia trifoliorum Erikss., by slugs
Authors: SHAKEEL M. A. , MOWAT D. J. 
Published: April 2006

AbstractSlugs of three species, Deroceras reticulatum, Arion fasciatus and A. subfuscus, which had fed on sclerotia or apothecia of Sclerotinia trifoliorum, transmitted the disease to water agar plates. In the case of Arion spp., transfer of excreta also produced infection.After feeding on apothecia D. reticulatum transmitted the disease to white clover plants, although the direct transfer of apothecia produced higher levels of infection. The visible symptoms of the disease were reduced when slugs were allowed to remain on the plants, apparently owing to a feeding preference of D. reticulatum for diseased leaf tissue.
The effects of temperature on digestibility of timothy (Phleum pratense L.), tested in growth chambers
Authors: THORVALDSSON G. 
Published: April 2006

AbstractPlants were grown in pots outdoors and placed in four growth chambers at different temperatures (day temperatures 9, 13, 17 and 21°C) and at three different phenological stages. They were then harvested at weekly intervals for up to 6 weeks. Pots left outdoors were harvested at the same time.Digestibility was nearly constant during the 6 weeks at the lowest temperature. The rate of decline in digestibility per day, calculated from that portion of the data which was assumed to be best for such estimation, was 0·060±0·008 per cent units for each degree increase in temperature.The results indicate that the temperature effect on decline in digestibility is the same for early as for late growth stages.
Evaluation of white clover varieties under grazing and their role in farm systems
Authors: EVANS D. R. , WILLIAMS T. A. , EVANS S. A. 
Published: April 2006

AbstractFour experiments were established in 1981–84 to investigate the effect of defoliation treatments on white clover varieties when grown with S23 perennial ryegrass. Treatments included a cutting only regime, as used in National List trials, and grazing systems simulating as near as possible those used on farms.Differential effects of cutting and continuous sheep stocking on white clover varieties, together with significant variety × defoliation interactions, illustrated the importance of the grazing animal in the evaluation of white clover. Differential effects of cattle and sheep grazing were also evident. Cattle grazing was less detrimental to white clover than was sheep grazing, i.e. cattle were not selective, and less stolon was removed. In general, with both cattle and sheep grazing the larger the clover leaf size the greater the loss in stolons, which in turn decreased persistency. The results illustrate how alternating cutting, sheep grazing and cattle grazing managements can be used to maintain optimum clover/grass balance.Successful clover/grass swards depend on the retention of clover, yet avoiding clover dominance. The difference in N transfer between clover varieties, especially those within the same leaf category, and the extra grass produced without fertilizer N, emphasized the importance of varietal choice. Breeding programmes have been concerned with the selection of larger‐leaved, long‐petioled varieties for growing in competition with grass in the presence of fertilizer N. However, the present results showed that, under continuous sheep stocking, increase in leaf size does not increase clover yield or persistency.The results presented emphasize the importance of the grazing animal in the evaluation of white clover varieties and indicate that yield of clover dry matter should not be the major criterion for selection of varieties for farm systems.
Anatomical structure and digestibility of reed canarygrass cultivars and hybrid ryegrass
Authors: GRABBER J. H. , ALLINSON D. W. 
Published: April 2006

AbstractAnatomical structure and fibre chemistry influence the digestibility of forage grasses. The objective of this study was to evaluate the anatomical structure, digestibility, and fibre composition of leaf blades from a high alkaloid and two low alkaloid cultivars of reed canarygrass (Phalaris arundinacea, L.) and one cultivar of tetraploid hybrid ryegrass (Lolium hybridum, Hausskn.). Cultivars were grown in a greenhouse in a randomized complete block design with four replications. Leaf blades were either cut into 10‐mm sections or dried and milled to disrupt anatomical structure.Reed canarygrass had smaller cells and airspaces and slower tissue digestion than ryegrass. The in vitro disappearance of ryegrass sections in buffered rumen fluid was 60% greater (P<0·01) than that of reed canarygrass after 6, 12 and 24 h of digestion. By contrast, the in vitro disappearance of milled ryegrass was similar to or less (P<0·05) than that of reed canarygrass. In vitro dry matter digestibility and fibre composition of the grasses were similar except for acid detergent fibre, which was greater (P<0·01) in ryegrass than in reed canarygrass. Reed canarygrass cultivars were similar in anatomical structure, digestibility, and fibre composition. It was concluded that the digestion of reed canarygrass, relative to ryegrass, was reduced by the compact arrangement of tissues and that alkaloid content did not influence the digestion of reed canarygrass cultivars.
Causes of low seed set in white clover (Trifolium repens L.)
Authors: PASUMARTY S. V. , MATSUMURA T. , HIGUCHI S. , YAMADA T. 
Published: April 2006

AbstractA field experiment was conducted to clarify the factors responsible for poor seed set in four white clover (Trifolium repens L.) cultivars. Although the mean number of ovules per floret was 5·18–5·29, the average number of seeds per floret was found to be only 1·23‐1·82. A stainclearing technique was used to examine the cytoplasmic state of the embryo sac in intact, unfertilized, mature ovules and it was found that 28–33% of ovules per carpel were sterile. The abortion rate of fertilized ovules and immature seeds (7 days after pollination) ranged between 32 and 34%. Beyond this period, it was observed that only a very small proportion of the total seeds were lost. The observation of high pollen fertility and a high pollen load strongly suggests that poor pollination does not account for the reduced number of seeds per floret. A ‘nutrient competition’ hypothesis was proposed for high ovule sterility and post‐fertilization abortion of developing seeds.
A comparison of diploid and tetraploid perennial ryegrass and tetraploid ryegrass/white clover swards under continuous sheep stocking at controlled sward heights. 2. Animal production
Authors: VIPOND J. E. , SWIFT G. , McCLELLAND T. H. , FITZSIMONS J. , MILNE J. A. , HUNTER E. A. 
Published: April 2006

AbstractPerformance of continuously stocked Mule ewes nursing Suffolk‐cross twin lambs over three grazing seasons, between April and August, was compared on swards of N‐fertilized diploid perennial ryegrass (D), tetraploid perennial ryegrass (T) and tetraploid perennial ryegrass with white clover (TC), the latter receiving no fertilizer N. Sward height was maintained by variable stocking rate close to a target of 4–6 cm (constant treatment) from turnout and compared in July and August with a rising sward height treatment (target 6–8 cm).Lambs on TC swards had significantly higher (P <0·001) liveweight gains compared with lambs on T swards by 41 gd‐1 in April–June and by 68gd‐1 in July‐August. Live weight and body condition score of ewes in August were significantly higher (P<0·001) on TC compared with T swards, by 11·3 kg and 0·75 respectively. Rising sward heights in July–August increased live‐weight gain of lambs compared with constant sward heights by 102, 39 and 54gd‐1 in consecutive years, associated with sward height increases of 0·9, 0·5 and 0·6cm respectively. Rising sward height increased ewe live weight and body condition score by 5·1 kg and 0·3 respectively, compared with results from constant sward heights. Effects of sward height and sward type were additive.T swards had a significantly (P<0·01) 16% greater overall lamb output than the D swards due mainly to a 10% higher achieved stocking rate. Stocking rates of ewes on TC vs T swards were 40, 13 and 12% lower in April‐August in successive years. The higher liveweight gain of lambs on the TC swards resulted in lamb outputs of 76, 105 and 101% of the T swards in successive years, showing that grass/clover swards containing over 20% clover could produce similar lamb output ha‐1 to grass swards given 150–180 kg N ha‐1.
Plant interference and chemical toxins in upland pastures
Authors: NORRINGTON‐DAVIES J. , BUCKERIDGE D. J. 
Published: April 2006

AbstractSupernatants derived from desiccated plant material gathered from Agrostis/Festuca vegetation had an inhibitory effect on the germination and early development of seedlings of Trifolium repens cv. S184. Two compounds, o‐hydroxyphenylpropionic acid and benzoic acid, were identified chromatographically and their structures confirmed by mass spectrometry. Commercial preparations of the two compounds were effective inhibitors at a concentration of 10−2 and 10−3m respectively when T. repens was used as the phytometer species. Benzoic acid lost its inhibitory effect when the pH of the two solutions was adjusted to pH 5·5. The roots of seedlings of white clover were severely distorted by o‐hydroxyphenylpropionic add at 10−3m. It is likely that phenolic acids, produced from the surface trash created by slot seeding procedures, interfere with the establishment of white clover in upland pastures.
Effects of inoculant treatment on silage fermentation, digestibility and intake by growing cattle
Authors: KEADY T. W. J. , STEEN R. W. J. , KILPATRICK D. J. , MAYNE C. S. 
Published: April 2006

AbstractA changeover design experiment involving thirty‐six 3‐month‐old Friesian male calves (mean initial live weight 127 kg) was carried out to evaluate a bacterial inoculant based on a single strain of Lactobacillus plantarum (Ecosyl, ICI) as a silage additive. On 25–31 August 1988, nine silages were harvested using double‐chop forage harvesters from the second regrowth of three swards, namely permanent pasture which had received 100 kg N ha−1 and perennial ryegrass which had received either 100 or 150 kg N ha−1. Herbages (mean DM and WSC concentrations 144 and 11·2 g kg−1 respectively) from each sward were treated with either no additive, formic acid (2·4 1 t−1) or the inoculant (3·3·1 t−1) and were ensiled in 126 silos of 0·8 t capacity. The only effects of the inoculant on chemical composition of the silages were a decrease in modified acid detergent fibre and an increase in endotoxin and crude and true protein concentrations. Silages were offered ad libitum and supplemented with 1·0 kg of concentrates per head daily for three periods each of 3 weeks in a partially balanced changeover design experiment. Digestibilities of the total diets were determined at the end of the experiment. For the untreated, formic acid‐treated and inoculant‐treated silages, silage dry matter intakes were respectively 3·58, 3·66 and 3·67 (s.e. 0·044) kg d−1, estimated metabolizable energy (ME) intakes were 46·1, 46·7 and 47·1 (s.e. 0·44) MJ d−1, energy digestibilities were 0·727, 0·727 and 0·738 (s.e. 0·0046) and organic matter digestibilities were 0·770, 0·771 and 0·788 (s.e. 0·0042). Rumen degradabilities of the silages were determined using two rumen‐fistulated cows. Mean dry matter and nitrogen degradabilities for the control, formic acid‐treated and inoculant‐treated silages, assuming an outflow rate of 0·05 h−1, were 10·508, 0·49, 0·491 and 0·702, 0·676 and 0·729. It is concluded that the inoculant significantly increased the digestibility of the silages but did not affect dry matter or ME intake.
Managing grass/clover swards to produce differing clover proportions
Authors: YARROW N. H. , PENNING P. D. 
Published: April 2006

AbstractManagement treatments were applied to an established ryegrass/white clover sward with the aim of producing differences in clover content. The treatments were: mowing (M) with no fertilizer N (intended to give high clover), grazing by cattle (C) with no fertilizer N (medium clover) and grazing by sheep (S) with 300 kg N ha−1 applied (low clover). Following treatments significant differences (P < 0.001) were observed, with M, C and S containing respectively. 237, 81 and 3 kg DM ha−1 of live clover. Treatment M swards had fewer ryegrass tillers but greater numbers of clover growing points than did treatment S, with values being intermediate on treatment C. Following overwintering most of the differences in the clover component between treatments C and M were lost, but those on treatment S still persisted. Management can be used to manipulate the botanical composition of ryegrass/white clover swards, but these changes may be only transient.
Leaf number as a criterion for determining defoliation time for Lolium perenne: 2. Effect of defoliation frequency and height
Authors: FULKERSON W.J. , SLACK K. 
Published: April 2006

AbstractThe object of this study was to determine the importance of frequency and height of defoliation on regrowth potential of Lolium perenne. Defoliation interval was based on stage of the regrowth cycle, as indicated by leaves per tiller.Simulated swards of Lolium perenne cv Yatsyn were grown as individual plants in a glasshouse kept at a day/night temperature of 25°C/15°C.Treatments imposed were defoliation at 2, 5 or 12 cm residual height, and low and high water soluble carbohydrate (WSC) level obtained by varying defoliation interval, i.e. defoliating at the 1‐leaf or 3‐leaf stage of the regrowth cycle. Regrowth after frequent short defoliations was only 65% of the less frequently defoliated plants taken over the full regrowth cycle. This was associated with a lower stubble WSC content (2·15 vs 17·5% in stubble) and a twenty‐seven‐fold difference in the amount of WSC in the stubble per plant. This difference in total WSC was a combined effect of more and heavier tillers and higher WSC content in stubble of plants defoliated less frequently at the end of the regrowth cycle. The regrowth of plants with WSC levels depleted by frequent defoliation when defoliated at 2 cm was significantly below that of those defoliated at 5 and 12 cm.The results indicate the desirability of defoliating plants at the 3‐leaf stage of the regrowth cycle. This not only allows the full regrowth potential to be expressed in that growth cycle, but also in the next cycle, by allowing the replenishment of WSC reserves and optimizing tiller status. The potential to regrow appears then to be based more on the total amount of WSC than the proportion of WSC in stubble.
The effect of light intensity after anthesis on dry matter distribution and seed yield of Lolium perenne L.
Authors: WARRINGA J. W. , MARINISSEN M. J. 
Published: April 2006

AbstractThe effect of light intensity after onset of anthesis on dry matter distribution, water soluble carbohydrate (WSC) concentration and seed filling in Lolium perenne was investigated in a pot experiment. Spaced plants of five clones were brought to flowering and exposed to four light intensities (24%, 57%, 100%, 115% of natural light) from 7 days after onset of anthesis onwards. The two oldest flowering tillers (i.e. the main and the first tiller) were separated from the rest of the plant and dissected after a seed‐filling period of 450°Cd (temperature sum counting from 7 days after onset of anthesis). Their stem dry weight and WSC concentration were reduced at the lowest light intensity. WSC amount was more reduced in the first, younger, tiller. Seed yield per ear of the main tiller was reduced by 14% because seed set and average seed weight were lower at the 24% light intensity. Seed yield and seed number per ear of the first tiller were lowered by 21% and 17%, respectively, at the 24% light intensity, but average seed weight was not. The relative contribution of the seeds to total tiller weight was about 20% and was similar for both tillers and all light intensities. WSC concentration and WSC amount in the stem + rachis were reduced only at 24% light in the main tiller and at 24% and 57% light in the first tiller. It is inferred that seed yield was not limited by assimilate availability, but by the ability of the seeds to utilize fully the abundantly available reserves in the stem. The tiller can support seed yield under a wide range of tight intensities.
The effects of ensiling on dry‐matter intake and milk production by lactating dairy cattle given forage as the sole feed
Authors: KEADY T. W. J. , MURPHY J. J. , HARRINGTON D. 
Published: April 2006

AbstractAn experiment involving forty‐five British Friesian cows in mid‐late lactation was carried out to evaluate the effects of ensiling on herbage digestibility, dry‐matter intake and milk production. The herbage from the primary growth of a predominantly perennial ryegrass sward that had received 123 kg N ha−1 was zero grazed (ZG) from 27 April to 24 May 1992. Before going onto the experimental diets all animals were offered a common silage as the sole diet and dry‐matter intakes and milk yields were recorded. The herbage was mown, picked‐up with a precision‐chop harvester and offered as the sole diet, twice daily, 10 fifteen cows that were on average 176 days into lactation. On May 20 herbage from the same sward was harvested identically to the ZG herbage and ensiled, alternative loads being untreated (UT) or treated with formic acid (2.4 l−1) (FA). For silages UT and FA respectively, pH values were 3.94 and 3.92 and ammonia nitrogen concentrations were 95 and 75 [g(kg total N−1)]. Forty‐two days after ensiling, the silages were fed twice daily as the sole diet to thirty cows which were on average 166 days into lactation. The feeding interval was 28 days and the last 7 days was the main recording period for each treatment. For diets ZG, UT and FA, dry‐matter intakes (DMI) (kg d−1), milk yields (kg d−1), fat plus protein yields (kg d−1). milk fat concentration (g kg−1), milk protein concentration (g kg−1)and fat plus protein yields [kg (kg DMI)−1] were 12.70, 11.51 and 12.07 (Av s.e.d. = 0.458); 12.79, 10.01 and 10.18 (Av s.e.d. = 0.346); 0.900, 0.649 and 0.682 (Av s.e.d. = 0.026); 39.8, 33.7 and 36.7 (Av s.e.d. = 0.174); 32.9, 29.9 and 30.0 (Av s.e.d. = 0.83); 0.073, 0.055 and 0.055 (Av s.e.d. = 0.003). UT treatment significantly increased dry matter (DM), organic matter (OM). energy and crude fibre digestibilities and the digestible OM concentration. UT and FA compared with ZG altered rumen fermentation patterns, significantly decreasing butyrate and increasing valerate concentrations. FA treatment significantly decreased the non‐glucogenic ratio. It is concluded that ensiling using formic acid had no effect on forage DMI relative to the parent fresh herbage. Ensiling either untreated or with formic acid significantly decreased milk yield and milk fat plus protein yield, resulting in a lower efficiency of conversion of DMI to milk fat plus protein.
A new technique to describe canopy characteristics of grass swards with spatial distribution, dry‐matter digestibility and dry weight of small‐size canopy components
Authors: HIRATA M. 
Published: April 2006

AbstractA new technique describing canopy characteristics of grass swards was developed In this technique, the sward canopy is regarded as a set of canopy components which are 2‐cm‐long segments of leaves and stems, and the spatial distribution, dry‐matter digestibility (DMD) and dry weight of the components are estimated. The technique was applied to a canopy of a bahia grass (Paspalum notatum Flügge) pasture in spring, summer and autumn. The spatial distribution in terms of the quantity and quality of components within the canopy can be described as can the dry weights of material in different DMD classes. From these descriptions, some important canopy characteristics were highlighted that cannot be identified with other techniques. They were the variation in DMD within a canopy, the possible difficulty for animals in discriminating between the components within a prehension bite, and the reduction in summer in the proportion of highly digestible components. Because of the way in which the canopy characteristics were described and the importance of the canopy characteristics highlighted, the technique is considered to be of potential value for describing canopy characteristics in relation to sward‐animal interactions during grazing.