bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of forage hydration on lag time during in vitro digestion of meadow hay
Authors: MILLER J. R. , HOBBS N. T.
Published: April 2006

Digestion of plant cell wall has been observed to be a first‐order process with an initial lag. Lag is defined as the period of time immediately after forage is exposed to the fermentive environment during which digestion does not occur or occurs at a greatly reduced rate. The effects of forage hydration on lag were investigated by focusing on the first 20 h of in vitro digestion of meadow hay. Samples were hydrated for 0, 1, and 16 h before fermentation. Digestion kinetics was estimated by both a first‐order kinetics model (KM) and an increasing relative‐rate model (RRM). Model parameters were obtained using a non‐linear least‐squares procedure. The effect of forage hydration was significant, especially for the 16‐h treatment. The RRM produced a better fit for the data from each treatment, and a better fit was obtained when each data set was analysed separately.
The productivity and response to inorganic fertilizers of species‐rich wetland hay meadows on the Somerset Moors: the effect of nitrogen, phosphorus and potassium on herbage production
Authors: KIRKHAM F. W. , WILKINS R. J.
Published: April 2006

The effects of fertilizer nitrogen (N), phosphorus (P) and potassium (K) on herbage production were investigated in herb‐rich hay meadows in Somerset, UK. Swards were cut after 1 July each year, followed by one or two aftermath cuts. Dry‐matter (DM) yield at cutting, metabolizable energy (ME) production and recovery of N, P and K were measured over 4 years.

Total annual DM production increased from 4·7t ha−1 without fertilizers to 10·5t ha−1 with 200 kg N, 75 kg P and 200 kg K ha−1 per year, and ME output from 38·8 GJ ha−1 to 92·5 GJ ha−1. Applying moderate replacement rates of P and K without N increased annual DM and N yields by 43% and 36% respectively, but N response was modest unless high rates of P and K were used. Annual ME output and recovery of N, P and K were all significantly increased by taking an additional, earlier cut for silage, even though DM yield was unaffected.

The results suggest that potential output of these meadows is similar to that of a wide range of less diverse permanent pastures. Data from this and a concurrent experiment will help to estimate the financial implications of fertilizer and cutting date restrictions within Sites of Special Scientific Interest and the wider Environmentally Sensitive Areas.
Effect of continuous stocking by sheep at four sward heights on herbage mass, herbage quality and tissue turnover on grass/clover and nitrogen‐fertilized grass swards
Authors: BINNIE R.C. , CHESTNUTT D. M. B.
Published: April 2006

The effects of continuous stocking by sheep at sward surface heights (SSH) of 3, 5, 7 and 9 cm in grass/clover (GC) and nitrogen‐fertilized grass (GN) swards were examined in relation to herbage mass and quality, clover content, tiller density and rates of herbage production and senescence in two periods in each of three grazing seasons (1987‐89). The GN swards received a total of 300 kg N ha−1 each year in six equal dressings from March; GC swards received a single dressing of 50 kg N ha−1 in March each year.

Herbage mass measured from ground level increased linearly with SSH with overall mean herbage masses of 0·89, 1·38, 1·78 and 2·12 t OM ha−1 (s.e.m.0·024, P < 0·001) at SSH of 3, 5, 7 and 9 cm respectively. GN and GC swards had mean herbage masses of 1·58 and 1·51 t OM ha−1 (s.e.m. 0·051, NS) respectively. Mean N content of herbage on GN swards was greater than that on GC swards and declined with increasing SSH. Crude, fibre (CF) content of herbage was similar for both sward types and increased with increasing SSH.

Clover content of GC swards remained low throughout the experiment, ranging from 0·002 to 0·074 of herbage mass. However, from tissue turnover rates it was estimated that its contribution to herbage production was in the range of 0·049–0·219 of net herbage growth.

Total growth increased with increasing SSH in both sward types, with maximum growth rates in GN swards of 143 and 130 kg DM ha−1 d−1 and in GC swards of 88·2 and 85·4 kg DM ha−1 d−1 in Periods 1 (up to early July) and 2 (after July) respectively. Senescence rates ranged between 13·3 and 50·1 kg DM ha−1 d−1 and tended to be higher in Period 2 than in Period 1. Net production increased with increasing SSH in Period 1, while in Period 2 net production declined at SSH above 6·5 cm.

The increased net herbage production in taller swards was not associated with greater utilized metabolizable energy production at sward heights above 5 cm.
The effects of incorporating sugar‐beet pulp with herbage at ensiling on silage fermentation, effluent output and in‐silo losses
Authors: FERRIS C. P. , MAYNE C. S.
Published: April 2006

Three studies were undertaken with the aim of examining in‐silo losses associated with ensiling mixtures of beet pulp and herbage. In Experiment 1, first‐regrowth perennial ryegrass was ensiled untreated or mixed with either 40 or 120 kg unmolassed beet pulp t−1 fresh grass prior to ensiling. In each of Experiments 2 and 3, second‐regrowth ryegrass was ensiled untreated or mixed with either 40, 80 or 120 kg unmolassed beet pulp t−1 fresh grass prior to ensiling. Dry‐matter concentrations of herbage ensiled in Experiments 1, 2 and 3 were 141, 157 and 139 g kg−1 respectively.

Time‐course studies indicated a more rapid fermentation with the untreated silages. Ensiling beet pulp with herbage resulted in significant improvements in silage fermentation, reflected in reductions in silage pH and ammonia nitrogen concentrations, with these effects being pronounced at beet pulp inclusion in excess of 80kg t−1. Beet pulp inclusion increased the dry‐matter concentrations of the resulting silages while reducing crude protein, modified acid detergent fibre and gross energy concentrations. In Experiment 1 beet pulp retained 1·62 and 1·641 effluent kg−1 at the 40 and 120kg t−1 application rates respectively. In Experiments 2 and 3, effluent retentions were 1·40, 1·29 and 0·93 1 kg−1 and 2·87, 2·19 and 1·781 kg−1 at the 40, 80 and 120kg t−1 beet pulp inclusion rates respectively. In each of Experiments 1 and 3, in‐silo losses were reduced with increasing level of beet pulp inclusion, while in Experiment 2 in‐silo losses were relatively unaffected by treatment. Nutrient losses in effluent were reduced by the inclusion of beet pulp in all three experiments, while nutrient losses in surface waste and invisible nutrient losses tended to increase with higher levels of beet pulp inclusion.

It is concluded that the inclusion of beet pulp with herbage at ensiling can result in an improved silage fermentation and a reduction in in‐silo losses, while at the same time retaining considerable quantities of effluent within the silo. However, with herbage dry‐matter concentrations below 160gkg−1, beet pulp inclusion in excess of 120 kg t−1 herbage would be required to eliminate effluent production totally.
Effects on milk production of feeding silage and three levels of sugar‐beet pulp either as a mixed ration or as an ensiled blend
Authors: FERRIS C. P. , MAYNET C. S.
Published: April 2006

Twenty‐one British Friesian dairy cows, in mid‐lactation, were used in a seven‐treatment, partially balanced change‐over design experiment consisting of three periods each of 4 weeks' duration. Treatments involved offering grass silage either without a sugar‐beet pulp (beet pulp) supplement (US) or supplemented with beet pulp at silage/beet pulp dry matter ratios of 80:20 (C40), 65:35 (C80) and 55:45 (C120), and offered in the form of a mixed ration. A further three treatments consisted of offering ensiled blends of silage and beet pulp, produced by mixing 40 (E40), 80 (E80) and 120 (E120)kg beet pulp t−1 of grass at ensiling. Silage was offered ad libitum on all treatments, with cows receiving 1kg d−1 of a concentrate supplement containing 470 g crude protein kg−1 fresh weight.

Dry matter intakes increased with increasing level of beet pulp inclusion in the diet, irrespective of method of beet pulp inclusion in the diet. Similarly, milk fat + protein yields increased with increasing level of beet pulp offered. However, when comparisons were made between the two methods of beet pulp inclusion in the diet with beet pulp requirements equivalent to those obtained in treatments C40, C80 and C120, namely 2·28, 4·53 and 6·21 kg d−1, offering beet pulp as a supplement to an untreated silage resulted in fat + protein yields of 32 (s.e.d. 9·8), 53 (s.e.d. 19·5) and 81 (s.e.d. 21·3)gd−1 greater than would have been achieved had equivalent quantities of beet pulp been included at ensiling as part of an ensiled blend. This effect can be attributed to the higher metabolizable energy intakes with the control silage supplemented with beet pulp at feeding, a consequence of the loss of nutrients from the beet pulp fraction during ensiling, in the case of treatments E40, E80 and E120. However, when account is taken of differences in the efficiency of recovery of edible silage dry matter between ensilage systems and differences in forage dry‐matter intake between treatments, overall efficiency of feed use was not significantly different between the two systems of beet pulp inclusion in the diet.
Enzymes as silage additives for grass–clover mixtures
Authors: SELMER‐OLSEN I.
Published: April 2006

Seven laboratory‐scale experiments were carried out to study the effects of cellulases/hemicellulases on silage fermentation of herbage from mixed swards of timothy (Phleum pratense), meadow fescue (Festuca pratensis) and red clover (Trifolium pretense). Enzyme‐treated silage (approximately 3500 HEC units kg−1 grass) reached a low pH sooner, had lower end pH, contained less NH3‐N and more lactic acid than did the untreated silage (P < 0·05). Applied with an inoculant, these effects were even stronger. With easily ensiled crops (experiments 1, 2, 5 and 6) preservation was first of all improved by inoculation of lactic acid bacteria; however, for the low‐sugar crops (experiments 3, 4 and 7) enzyme treatment was more significant. The enzymes derived from Aspergillus spp. gave more acetic acid than the enzymes from Trichoderma reesei. The Trichoderma enzymes liberated 4·8 g WSC kg−1 FM gamma‐irradiated grass during 60 d at pH 4·3 (P < 0·05). On average, for all silages enzyme treatment increased the sum of residual sugar and fermentation products by 3·7 g kg−1 FM (21 g kg−1 DM) compared with the silages not treated with enzymes (P < 0·001). Enzyme treatment increased the instantly degradable part of the feed, but total in sacco and in vitro digestibilities were not affected.
Effects of delay in reapplication of nitrogen fertilizer following cutting silage from a ryegrass sward
Authors: SHELDRICK R. D. , LAVENDER R. H. , MARTYN T. M.
Published: April 2006

Plots of a 2‐year‐old sward of Merlinda perennial ryegrass received a routine dressing of 100 kg N ha−1 as compound fertilizer in March 1991, followed by further dressings of 100 kg N ha−1 after cuts 1, 2 and 3 in a simulated four‐cut silage system, either the same day as cutting or with a delay of 3, 7, 10 or 14 d. Partial irrigation ensured that fertilizer could be taken up immediately. Annual total dry matter yield, the dry matter yield for the experimental cuts 2–4 and their apparent response to N showed no effect of delays of 0–10 d in reapplication of fertilizer, but a significant (P < 0·01) reduction for 14 d delay. Significantly (P= 0·001) higher apparent recovery of N in the cut herbage was recorded where reapplication of fertilizer had been delayed by 7 or 10 d (93% and 91% respectively) in comparison with either smaller (0 delay, 78%; 3 d delay, 87%) or greater delay (14 d, 86%). It is suggested that lower recoveries at 0 and 3 d result from the sward's reduced NO3 uptake following defoliation and that, while in practical situations the conditions may not be as rigorous as those imposed in this experiment, further experiments to determine the fate of N not recovered in the herbage are warranted, so defining management circumstances in which immediate reapplication of N might not be advisable.
Effect of early season sward management on sward quality and lamb liveweight gain during autumn
Authors: CHESTNUTT D. M. B.
Published: April 2006

In two experiments (1990 and 1991) perennial ryegrass (cv. Talbot) pasture was subjected to six different management treatments by adjusting stock numbers to achieve set sward heights for set periods between turn‐out in early April and weaning in early July. The main objective of the experiments was to measure the effect of differences in sward management up to July on subsequent sward type, and the effect of sward type on the performance of weaned lambs between mid‐July and early October when all swards were grazed at a sward height of 7 cm. In Experiment 1 swards were grazed at 7 cm initially and then reduced to 3 cm at various dates and maintained at 3 cm until early July. In Experiment 2 swards were grazed initially at 7 cm, and this was reduced to 3 cm and then allowed to return to 7 cm at various dates up to early July.

Grazing at a sward height of 7 cm up to weaning, in early July, gave mean twin lamb growth rates of 310 g d−1, while at a tower sward surface height of 3 cm lamb growth rate was reduced to 206 g d−1 The density of seed heads produced from July was strongly influenced by earlier management. Grazing at 7 cm up to July gave a high density of seed heads (213m−2), and this reduced (126 m−2) by grazing to 3 cm. Seed heads were almost eliminated (17 m−2) by grazing at 7 cm until late June followed by grazing down to 3 cm in early July. Reducing sward surface height from 7 cm to 3 cm at an earlier date tended to increase the development of seed heads from early July. Where swards were grazed from 7 cm to 3 cm and then allowed to return to 7 cm, the later in the pre‐weaning period this took place the greater the reduction in seed head development. Greater seed head density was associated with a significant decrease in the nitrogen content of the herbage on offer in Experiment 2, but an increase in modified acid detergent (MAD) fibre content was not significant.

Despite the differences in the sward type on offer, the effect on weaned lamb growth rate was small. Lamb liveweight gain during autumn was significantly reduced in Experiment 2 following earlier grazing at 7 cm compared with 3 cm, but liveweight gain differences in Experiment 1 were not significant.
Concentrations of N, P, K, Ca, Mg and Na in perennial ryegrass and white clover leaves of different ages
Authors: WILMAN D. , ACUÑA P. G. H. , MICHAUD P. JOY
Published: April 2006

Leaf blades of perennial ryegrass (Lolium perenne) at five developmental stages, from unemerged to dead, were collected from cut swards grown under field conditions. Similarly, leaflets of white clover (Trifolium repens) at four developmental stages, from tightly folded to proximal to the youngest fully developed leaf, were collected. The leaves were analysed for N, P, K, Ca, Mg and Na.

In perennial ryegrass, the concentration of N declined by about half and those of P and K declined by about two‐thirds, as leaves aged. By contrast, the concentration of Ca increased more than fivefold and that of Mg about twofold as leaves aged. The concentration of Na initially increased more than twofold but then declined as leaves died. In white clover the concentration of N declined by about 20% as leaves aged, while the concentrations of P and K declined by about 50%; the concentration of Ca increased about fivefold, that of Mg declined by about 15% and that of Na increased by about 15%.

The application of N increased the concentrations of N and K in ryegrass leaf blades at all stages of development. The application of P increased the concentrations of P and Na in the leaves of both species.
The intake and performance of cashmere goats grazing sown swards
Authors: MERCHANT MARGARET , RIACH D. J.
Published: April 2006

An experiment was conducted to examine the relationships between sward surface height and the intake and liveweight gain of lactating female goats and their single kids and of 12‐month‐old castrated male goats continuously grazing grass pasture. Herbage intake was measured using the n‐alkane marker technique. Goats grazed the experimental area from May to August at nominal sward heights of 3–4, 5–6, 7–8 and 9–10 cm. Sward heights achieved were variable but were consistently ranked in treatment order.

The herbage intake of females [57‐140 g DM (kg LW0.75)−1 d−1] and castrates [26‐88 g DM (kg LW0.75)−1 d−1] increased linearly with sward height over the range 3.2‐11.0 cm. The liveweight change of females and castrates reflected the pattern of change in sward height.

The herbage intake of kids [17‐41 g DM (kg LW0·75)−1 d−1] was not related to sward height, but there was a consistent increase in liveweight gain with sward height from 98 to 129 g d−1. The herbage intake of kids did not increase with age with means of 25–29 g DM (kg LW0·75 d−1 for kids aged 9–17 weeks.

There was evidence that all classes of goat selected green leafy material of high digestibility.
Effects of treating low dry‐matter grass with a bacterial inoculant on the intake and performance of beef cattle and studies on its mode of action
Authors: KEADY T. W. J. , STEEN R. W. J.
Published: April 2006

A randomized block design experiment involving thirty beef cattle (mean initial live weight 462 kg) was carried out to evaluate a bacterial inoculant based on a single strain of Lactobacillus plantarum as a silage additive and to provide further information in relation to its mode of action. Three herbages were harvested on 10 August 1989 using three double‐chop forage harvesters from the first regrowth of a perennial ryegrass sward which had received 170 kg N, 25 kg P2O5, and 42 kg K2O ha−1. They received either no additive (silage C), formic acid at 2·91 (t grass)−1(silage F) or the inoculant at 3·21 (t grass)−1 (silage I). Mean dry‐matter (DM), water‐soluble carbohydrate and crude protein concentrations in the untreated herbages were 158g kg−1, 88 g (kg DM)− and 183g (kg DM)−1 respectively. For silages C, F and I respectively, pH values were 4·01, 3·57 and 3·62; ammonia N concentrations 117, 55 and 77 g (kg total N)−1; and butyrate concentrations 2·18, 0·50 and l·24g (kg DM)−1. The silages were offered ad libitum and supplemented with 2·5 kg concentrates per head daily for 77 days. For treatments C, F and I, silage DM intakes were 6·59, 7·25 and 6·80 (s.e. 0·074)kg d−1; metabolizable energy (ME) intakes 86,99 and 94 (s.e. 0·8) MJ d−1; liveweight gains 0·90, 0·97 and 1·02(s.e.0·066) kg d−1; carcass gains 541,656 and 680 (s.e. 34·0) g d−1. Inoculant treatment increased DM (P < 0·01), organic matter (P < 0·01), crude fibre (P < 0·05), neutral detergent fibre (NDF) (P < 0·05) and energy (P < 0·05) digestibilities, the digestible organic matter concentration (P < 0·01) and the ME concentration (P < 0·05) of the total diets. Additive treatment altered rumen fermentation patterns but had little effect on the rumen degradability of silage DM, modified acid detergent (MAD) fibre, NDF or hemicellulose. It is concluded that treatment with the inoculant improved silage fermentation and increased digestibility, had little effect on silage DM intake but significantly increased carcass gain to a level similar to that sustained by a well‐preserved formic acid‐treated silage
Effect of supplementation on production by spring‐calving dairy cows grazing swards of differing clover content
Authors: WILKINS R. J. , GIBB M. J. , HUCKLE C. A. , CLEMENTS A. J.
Published: April 2006

An experiment was carried out to examine the effect of supplementation on the performance of spring‐calving dairy cows grazing swards of differing perennial ryegrass and white clover content. Seventeen heifers and sixty‐four Friesian cows in their third to ninth week of lactation were turned out onto one of three pastures with different proportions of perennial ryegrass and white clover. Nine animals on each pasture received either 0, 2 or 4 kg d−1 of a concentrate with a crude protein concentration of 180 g kg−1 dry matter (DM). Prior to grazing, swards contained proportionately 0·01 (L), 0·15 (M) and 0·20 (H) of total DM as clover. During the experiment, grazing pressures were adjusted by movement of buffer fences to maintain compressed sward heights at 6 cm. Samples taken 26 and 68 d after the start of grazing showed little change in the proportion of clover in sward L (< 0·01 and 0·02 respectively), but convergence in the proportion of clover in swards M and L (0·08‐0·16 and 0·10‐0·15 respectively). Mean daily yields of milk, fat, protein and lactose increased significantly with increased clover content and, even without supplementation, daily yields were 25·4, 0·98, 0·73 and 1·09 kg respectively on sward H. Of the milk components, only protein was significantly increased by increasing sward clover content. The response in milk yield to supplementation was greater on sward L than on swards M and H.
Influence of root competition on compatibility between white clover and perennial ryegrass populations during seedling establishment
Authors: COLLINS ROSEMARY. P. , RHODES I.
Published: April 2006

Plants of a white clover population, Ac 3785, were grown in binary mixtures with perennial ryegrass cv. Talbot and the ‘coexisting’ population, Ba 10281, in boxes. Treatments imposed were ‘no root competition’ and ‘full competition’, which prevented or allowed the root systems of the competing species to intermingle respectively. Shoot competition was permitted in both treatments. Measurements of dry‐matter yield and leaf area of the clover and grasses were made on three occasions following sowing.

The dry‐matter yield of both grasses was higher than that of clover at all three harvests and under both treatments, and this yield advantage tended to increase with time. Both grasses yielded more under full competition than where root competition was prevented. Talbot was higher yielding than the coexisting population under both treatments. Clover dry weight and leaf area index (LAI) were considerably higher under the ‘no root competition’ treatment. There was no effect of companion grass on clover dry weight, but clover LAI was significantly higher with its coexisting population than with Talbot in the ‘no root competition’ treatment.

The LAI and dry weight data indicate that clover leaf morphology changed in response to the companion grass where root competition was prevented. Thus, the superior aerial compatibility of Ac 3785 with its coexisting grass was limited by below‐ground factors. Possible ecological reasons for this effect are discussed.
Forage availability from a temperate pasture managed with intensive rotational grazing
Authors: KANNEGANTI V. R. , KAFFKA S. R.
Published: April 2006

Successful integration of rotational grazing into livestock production systems requires estimates of pasture growth rates for feed budgeting of daily animal intake. By matching livestock nutrient demand with forage availability, over‐feeding of supplements can be minimized, which reduces feed costs and the need lo manage surplus nutrients, A three‐year grazing study was carried out on a Kentucky bluegrass (Poa pratensis L.)‐dominant pasture to estimate the daily quantity of herbage available to cattle in an intensive, rotational grazing system. Herbage production, species composition, and forage quality were determined in each of the six grazing cycles in a year, from April until September. The average length of a grazing cycle was 28·6 d, with 2·7 d for duration of grazing on a paddock. Pre‐grazing and post‐grazing sward heights, measured with a plate meter, were 14 and 7 cm, and the corresponding herbage masses were 1955 and 775 kg DM ha−1 respectively. Under adequate soil moisture during 1989, herbage available for daily intake was 53 kg ha−1 from April until mid‐ August, declining to approximately 32 kg ha−1 d−1 by the end of September. Distribution of this herbage was fairly uniform until the end of August. However, a dry summer in 1991 reduced herbage availability to 15 kg ha−1 d−1. Bluegrass and white clover (Trifolium repens L.) formed 70% of the herbage yield during the period April–June. Later in the season, dead matter and other species increased, reducing the contribution of bluegrass and clover to approximately 60% of total dry matter. While these pastures have the potential to provide significant amounts of forage for 5–6 months in a year, additional on‐farm forage reserves are needed during periods of water stress.
The composition of first‐cut grass for ensilage in England and Wales from 1988 to 1991
Authors: HAIGH P. M.
Published: April 2006

A total of 2225 samples of herbage, typical of that taken for first‐cut silage on commercial farms in England and Wales, was taken between 1988 and 1991. Samples were analysed for dry matter (DM), water soluble carbohydrate (WSC), crude protein (CP) and metabolizable energy calculated from modified acid detergent fibre. The results were used to investigate the effect of weather conditions upon herbage quality for ensilage. In general, in areas of high rainfall, i.e. western areas, herbage DM and WSC were significantly lower than in eastern areas, whilst the reverse situation occurred with CP. Italian ryegrass (IRG) had a significantly higher WSC and lower CP than other grasses, whilst samples from permanent pasture (PP) had significantly lower DM and WSC, and significantly higher CP than other grasses. It was calculated that to produce a WSC concentration in the fresh grass of 37 g kg−1, to produce well‐fermented silage without additive use, IRG grown in the east would require a DM of 160 g kg−1, In contrast PP grown in the west would require a DM content of 250 gkg−1.
A comparison of the ensilage, in an anaerobic cabinet, of grass, either fresh or when thawed after deep freezing
Authors: WAYMAN J. , CHAMBERLAIN D. G. , WILLIAMS A. G.
Published: April 2006

The suitability of freezing a large amount of grass from a single harvest for use in a series of experiments to investigate silage fermentation and its manipulation was examined. Perennial ryegrass, harvested in late June, was ensiled in sterile polythene bags inside an anaerobic cabinet; some was also stored frozen at ‐20°C for up to nine months before ensiling in a similar manner. The course of fermentation was followed using not only conventional chemical and microbiological analyses, but also by measuring microbial metabolic activity in vitro. Freezing and thawing affected the chemical composition and the microbial populations on the grass, and there were differences in the changes occurring in thawed grass during ensilage, probably related to damage to plant cells and impaired microbial activity associated with freezing and thawing. For both the grasses and the silages made from them, it was clear that the number of microorganisms present was not a reliable guide to microbial metabolic activity. Although the fermentation of frozen‐and‐thawed grass did not simulate precisely the fermentation occurring with fresh grass, it is concluded that, when used judiciously, the ensilage of thawed grass can be a useful experimental tool, particularly in the initial screening of manipulants of fermentation.
Infestation of improved grasslands by Juncus effusus L. in the catchment of the River Tyne, Northern England: a field survey
Authors: CHERRILL A.
Published: April 2006

Soft rush, Juncus efffusus L., is a widespread weed of managed grasslands. In 1991, a sample‐based field survey of the weed's distribution in improved grasslands was conducted within the catchment of the River Tyne in Northern England. The land classes of the Institute of Terrestrial Ecology (ITE) environmental landscape classification system were used as sampling strata. In total, 182 I‐km grid squares were surveyed. Areas of improved grassland and levels of J. effusus infestation differed significantly between land classes, but there was also wide variation between grid squares within land classes. Most squares within a land class had no J. effusus, while a proportion had large areas. Extra‐polation from the sample data suggested that an area equivalent to 24·0% of the 3000km2 land surface of the catchment supported improved grassland, of which 3·5% was infested with the rush. Infestation of improved grassland was estimated to be lowest in the lowlands (2·0% of improved grassland), intermediate in the marginal uplands (3·0% of improved grassland) and greatest in the uplands (10·8% of improved grassland). Data from the Farm Business Survey, on broad patterns of utilization of improved grassland for hay, silage and livestock in lowland, marginal upland, and upland landscapes in the catchment, do not readily explain the observed variation in infestation levels, which may reflect local factors and the availability of propagules from adjacent rough grazing land.
Characteristics of microsites with and without white clover in two field swards
Authors: MATTHEW C. , CRESSWELL A. , HAGGAR R. J.
Published: April 2006

A microsite comparison technique was used to characterize differences between clover and non‐clover patches in two field swards, one grazed by cattle and the other sheep‐grazed. Within clover patches of both swards, ryegrass tiller weight and the percentage of dead dry matter (DM) was lower than in non‐clover patches, while the ratio of other grass DM: ryegrass DM was higher. Leaf senescence rates for ryegrass tillers within clover patch microsites were less than half of those of non‐clover patch microsites, and consequently net leaf production was higher. At clover patch microsites, soil carbon dioxide levels were lower, soil oxygen levels higher and levels of N, Na, Ca, Mg and P in the ryegrass component of the herbage DM were elevated, compared with non‐clover patch microsites.
Sward dynamics of a smooth‐stalked meadowgrass dominantwhite clover sward rotationally grazed by cattle and/or sheep
Authors: MURPHY W. M. , BARRETO A. D. MENA , SILMAN J. P.
Published: April 2006

This experiment was carried out to study the responses of sward components (particularly white clover, Trifolium repens) to grazing management in a natural sward dominated by smooth‐stalked meadowgrass (Poa pratensis) syn. Kentucky bluegrass. Treatments during two grazing seasons (1989–90) were: cattle grazing alone (C); cattle grazing followed by topping (CT); cattle grazing followed by sheep grazing (CS); and sheep grazing alone (S). Mean target pre‐ and post‐grazing herbage masses were 2200 and 1100 kg DM ha−1, estimated by single‐probe electronic capacitance meter. Sward component dynamics were monitored using turf dissections, marked white clover stolons, and ring‐toss white clover leaf counts. Component and sward data for the C, CT, CS and S treatments respectively, were: number of white clover leaves m−2, 1295, 1384, 1408, 900 (s.e. ± 108); number of leaves per growing point, 3·2, 3·4, 3·0, 2·8 (s.e. ± 0·2); herbage accumulation (t DM ha−1), 5·16, 5·02, 5·87, 8·28 (s.e. ±0 08); rejected herbage (% pasture area) 39·7, 7·7, 16·0, 0 (s.e. ± 75); and annual net herbage production (t DM ha−1) 3·39, 4·35, 4·99, 8·28 (s.e. ± 0.07). Swards grazed by sheep alone contained less white clover, but regrew quicker and produced more herbage than other treatments. Close topping or grazing by sheep following dairy cattle grazing decreased sward rejection by cattle. These treatments maintained more of the pasture in better condition for subsequent cattle grazing, resulting in greater net herbage production than where no post‐cattle grazing treatment was used.
The effects of treating low dry‐matter, low digestibility grass with a bacterial inoculant on the intake and performance of beef cattle, and studies on its mode of action
Authors: KEADY T. W. J. , STEEN R. W. J.
Published: April 2006

This experiment evaluated a bacterial inoculant based on a single strain of Lactobacillus plantarum as a silage additive. Three silages were harvested on 8 September 1989 from the second regrowth of a perennial ryegrass sward, which had received 167 kg N, 28 kg P2O5 and 45 kg K2O ha−1. Mean dry matter (DM) and water soluble carbohydrate concentrations of the herbages at ensiling were 148 g kg−1 and 78 g.(kg DM)−1 respectively. Herbages were treated with either no additive (C), formic acid (3·0 1 t−1) (F) or the inoculant (3·0 1 t−1) (I) and were ensiled in three 80‐t capacity silos. For silages C, F and I respectively, pH values were 4·70, 3·77 and 4·47, ammonia‐N concentrations were 192, 111 and 182 g (kg total N)−1 and butyrate concentrations were 6·8, 1·8 and 7·1 g (kg DM)−1. The silages were offered ad libitum and supplemented with 2·0 kg concentrates per head daily to thirty‐six heifers (mean initial live weight 442 kg). For silages C, F and I, silage DM intakes were 12·7, 14·4 and 14·1 (s.e. 0·42) g (kg live weight)−1, metabolizable energy intakes were 155, 166 and 172 (s.e. 5·1) kJ (kg live weight)−1, and estimated carcass gains were 456, 519 and 518 (s.e. 28·1) g d−1 respectively. A further 18 similar cattle were used in studies on the digestibility of the silages, and rumen degradation of each was estimated with three mature cattle. Inoculant treatment significantly increased crude fibre (P <0·01), neutral detergent fibre (P <0·01), modified acid detergent fibre (P <0·01), hemicellulose (P <0·05) and N digestibilities (P <0·05) and tended to increase N retention from the total diet. It is concluded that although treatment of herbage that was difficult to ensile with the inoculant did not improve silage fermentation, it significantly increased digestibility, especially of the fibre fractions, and silage DM intake and tended to increase animal performance to levels similar to those achieved with a well preserved formic acid‐treated silage. Increases in silage DM and metabolizable energy intakes are likely to have been attributable to the effects of the inoculant on digestibility, especially of the fibre fractions.
Effect of sheep, deer and cattle dung on herbage production and soil nutrient content
Authors: WILLIAMS P. H. , HAYNES R. J.
Published: April 2006

A field experiment compared the effects of sheep, deer and cattle dung on pasture growth and soil nutrient status. Sheep and deer dung pellets degraded rapidly within three to eight weeks, while it was 12 months before all visible cattle dung had gone from the soil surface. The cattle dung initially reduced herbage yield owing to smothering. However, after 40 days, herbage around the edges of the dung patch responded positively to the dung and more dry matter was produced in this patch than in the control patch during the first 12 months. There was no measurable herbage response to sheep dung, but deer dung significantly increased herbage production. While the rate of nutrient application per unit area was similar for sheep and deer dung, the latter was more evenly spread within the patch area. Consequently, a greater percentage of pasture plants in the patch received nutrient additions from the deer dung and a measurable response was recorded. Twelve months after dung application, soil nitrate, phosphate and organic C were higher in dung patches than in the control patches. In cattle dung patches, this response was accompanied by higher microbial biomass C levels, arylsulphatase and arylphosphatase activities. Some residual effect on organic C levels was still evident three years after cattle dung application.
Relationship between vegetation state and bite dimensions of sheep grazing contrasting plant species and its implications for intake rate and diet selection
Authors: EDWARDS G. R. , PARSONS A. J. , PENNING P. D. , NEWMAN J. A.
Published: April 2006

This study used both experimental evidence and a mathematical model to address some differences in interpretation in the literature on the relationship between sward height and the bite dimensions (bite depth, bite area and bite mass) of sheep grazing contrasting vegetation types. Individual non‐fasted sheep were released onto small areas (10 × 10m) of white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) and bite dimensions were measured as they grazed across patches (0·7 × 0·7 m) of predetermined sward surface height (SSH). Sward heights were 4, 7, 10, 13 and 16cm for white clover patches and 4, 6, 5, 9, 11·5 and 14cm for ryegrass patches. Four sheep were assigned to each plant species and each sheep grazed one patch of each height (five patches/sheep). Bite depth, bite area and bite mass increased linearly with SSH in both white clover and ryegrass. At a given SSH, bite depth was similar in white clover and ryegrass, but bite area and bite mass were greater in white clover than in ryegrass. The linear relationships observed between bite mass and SSH contrasted with the asymptotic relationships observed in some other studies, but it is suggested that different relationships may arise because of methodological differences between studies. Furthermore, when linear relationships for bite mass were compared with asymptotic relationships for bite mass in a mechanistic model of animals grazing from ryegrass‐white clover pastures it was demonstrated that the nature of the relationship had relatively little effect on the relationship between intake rate and SSH. This was because intake rate depended on the fundamental mechanistic relationship between bite mass and prehension bite rate. This relationship meant that the greater bite masses found when linear relationship were assumed were associated with reduced prehension bite rates and thus the effect on intake rate was relatively small. In addition, the predictions of the model regarding the bases of diet selection by animals grazing ryegrass‐white clover mixtures were simplified, and stabilized, when linear relationships were assumed.
The effect of sward height and its direction of change on the herbage intake, diet selection and performance of weaned lambs grazing ryegrass swards
Authors: ARMSTRONG R. H. , ROBERTSON E. , HUNTER E. A.
Published: April 2006

Abstract Four sward height treatments were imposed by continuous variable stocking using at least ten Suffolk × Greyface lambs per plot from late July to late August: constant 3·5 cm. constant 6·0 cm. 3·5cm increasing to 6·0 cm and 6·0 cm decreasing to 3·5 cm. The treatments were established on two swards given fertilizer N applications over the season of 97 and 160 kg N ha−1 respectively.

Animal density was greater on the high fertilizer treatment, at the lower sward height and especially on the decreasing height treatments. Liveweight change of lambs was higher (P <0·001) on the 6‐cm than on the 3·5‐cm treatments (+159 vs‐13g d−1 and was also higher (P <0·001) on the increasing than on the decreasing sward height treatments (+92 vs‐26 g d−1). Herbage organic matter intake (OMI), measured on two occasions in the experiment, was greater (P <0·001) on the 6·0 cm than on the 3·5‐cm sward heights whereas values for the increasing sward height treatments were much greater than those for the decreasing sward height treatments. There was little difference in the organic matter digestibility of the diet between treatments. Diets were composed largely of lamina, although there was more pseudostem and dead herbage in the diets of Iambs grazing the decreasing than the increasing sward height treatments at the end of the experiment. Bite mass was closely related to OMI but the treatment and period differences were relatively greater than for OMI. Bite mass was more closely related to the depth of the lamina layer (sward height‐pseudostem height) than it was to sward height. There was evidence that pseudostem acted as a barrier to defoliation on these short swards and also that the proportion of youngest leaf in the diet was positively related to sward height and to increases in sward height.

Sward height and especially the direction of change in sward height, together with associated stock density, were potent influences on lamb growth rate. This was a consequence of differences in herbage intake, which was strongly influenced by bite mass.
The effect of sward height on the liveweight gain of farmed yearling red deer (Cervus elaphus) stags
Authors: HAMILTON W. J. , SIBBALD M. A. , FEIST D.
Published: April 2006

The effect of sward height on the liveweight gain of yearling farmed red deer stags grazing permanent upland pastures in the UK in two successive years is described. The swards received nitrogen fertilizer at a rate of 218 kg ha−1. Red deer stag calves, which had been weaned in September and housed over winter on a hay and concentrate diet to gain on average 57 g d−1 in year 1 and 75 gd−1 in year 2, grazed at one of fourmean sward heights of 4, 6, 8 and 10cm from the beginning of June until September. Liveweight gains were recorded over a period of 15 weeks. All animals were slaughtered and carcass weights were recorded after the end of the grazing period. Liveweight gains and final live weights and carcass weights were significantly (P<0·05) lower on the 4‐cm sward than on the other swards, but there were no differences between the performance of animals on the 6‐, 8‐ and 10‐cm swards.
The manipulation of grass swards for summer‐calving dairy cows
Authors: FISHER G. E. J. , ROBERTS D. J. , DOWDESWELL A. M.
Published: April 2006

Two experiments examined the effects of different defoliation treatments in spring on sward morphology and animal performance in mid‐season and late season. Three treatments were applied in both experiments: Control (C), sward grazed by cows in spring to 6–8 cm grass height. Grazed Aftermath (GA). sward grazed by cows in spring to 3–4cm and allowed to regrow before being grazed by summer‐calving cows, Silage Aftermath (SA), sward not grazed in spring, but a primary cut taken and the sward allowed to regrow before being grazed by summer‐calving cows. The aim of treatment GA was to produce a sward with a high tiller density and high intake characteristics to meet the forage intake requirements of continuously grazed summer‐calving cows, without resorting to offering forage buffers. Experiment 1 was conducted in 1989 on a sandy loam soil and Experiment 2 in 1990 on a heavy loam soil.

In both experiments the GA treatment led to high live tiller density and live: dead tiller ratios compared with the C and SA treatments. Differences in sward morphology were also detected by applying double normal distribution analyses to measurements of grass height. The GA treatment also increased sward herbage mass and, to a limited extent, herbage metabolizable energy and crude protein contents. The results from Experiment 1 suggested that these sward effects lead to increased herbage dry‐matter intake (as estimated by the n‐alkane technique) and milk yield in cows grazing the GA sward. However, in Experiment 2, where conditions for grass growth in mid‐season were more favourable than in Experiment 1, the differences in sward morphology produced in spring were quickly lost in June and July. There were therefore no differences in herbage intake or milk yield in the second experiment. Herbage intakes (kgDMd−1± s.e.d) estimated in July for cows on treatments C, GA and SA were 11·0, 13·4, 10·1 ± 2·16 for Experiment 1 and 10·7, 11·1, 11·2 ± 2·32 for Experiment 2. Average milk yield (kgd−1± s.e.d.) for cows on treatments C, GA and SA were 26·1, 28·0, 25·6 ± 0·31 (Experiment 1) and 28·5, 27·3, 28·4 + 0·58 (Experiment 2).

The results suggested that acceptable milk yields can be obtained from grazing summer‐calving cows, without offering forage buffers, by applying high stocking rates (low grass heights) in spring. However, the benefits of this manipulation could be lost by lax grazing in mid‐season.
The use of roll‐conditioning and potassium carbonate (K2CO3) to increase the drying rate of lucerne (Medicago sativa L.)
Authors: MEREDITH R. H. , WARBOYS I. B.
Published: April 2006

Mechanical and chemical treatments to accelerate the drying of cut lucerne were evaluated under laboratory conditions. Plant material was treated with a 016 M solution of potassium carbonate (K2CO3) and/or lightly pressed between a pair of smooth rollers (roll‐conditioning).

Drying times to 33% moisture content (MC), expressed on a dry weight basis (dwb), were reduced by 49% by roll‐conditioning, 76% by K2CO3) treatment and 77% by the combined K2CO3+ roll‐conditioning treatment. The main benefit from combining the two forms of treatment was an improved uniformity of drying; when whole shoots were at 61% MC (dwb) the difference between leaf and stem moisture contents was reduced by 28% (roll‐conditioning), 38% (K2CO3) and 54% (K2CO3+ roll‐conditioning) relative to the untreated control.
Quality of grass silage infected with spores of Clostridium tyrobutyricum
Authors: RAMMER CHRI
Published: April 2006

The influence of adding clostridial spores to silage was studied in 2 successive years. Direct‐cut, precision‐chopped herbages were infected with spores of Clostridium tyrobutyricum in doses varying from 0 to 106 g−l fresh material (FM), and ensiled in experimental silos. The material was treated with or without 4 ml formic acid (85%) kg−1 FM. Silo contents were studied after 4.20 (or 50) and 100 days of ensiling.

Contents of dry matter, water‐soluble carbohydrate, nitrate as well as buffering capacity of FM varied between the 2 years at harvest, whereas the numbers of clostridial spores were about the same (< 102 g−1).

Infecting the crop with clostridial spores negatively affected the quality of silage in the first year. After 50 days spore numbers in the silages had increased by 40 × 103 to 150 × 103 times in the infected silage, compared with 5 × 103 in the uninfected silage. No effect was seen in the second year.

Silage with high spore counts showed no residual nitrate content. Formic acid improved silage quality from a chemical point of view but had no anti‐clostridial effect. Ensilability of a crop seems to be more important than the initial count of Clostridia for a successful ensiling process.
Effect of forage removal at the first detectable node stage on the growth of winter and spring triticale
Authors: ROYO C. , ROMAGOSA I.
Published: April 2006

The effect of forage removal on the growth of five winter and five spring triticale genotypes was studied in 1992 and 1993 in field experiments in north‐eastern Spain. When cut, winter triticales produced more biomass and leaf area than spring types owing to their higher tillering capacity. The leaf area index (LAI) at anthesis was similar in both groups in both clipped and uncut plots, but spring triticales had a greater leaf area on the main stem than winter types. Winter types had a greater leaf area on the tillers than spring types. Spring and winter types had a similar physiological response to forage removal, except for modifications in flag leaf area. In spring types triticale flag leaf area was reduced by clipping, whereas in winter types flag leaf area was increased. Forage removal resulted in less dry‐matter accumulation in all plant parts, maximum weight of the plant being reduced by about 20% and the rate of growth by around 13%. LAI at anthesis decreased by 37% as a result of clipping, and the leaf area duration from anthesis to maturity decreased by 36%. The duration of growth increased after clipping. Heading, anthesis and maturity dates were delayed by clipping, but grain filling duration was not affected.