bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE PHYSIOLOGICAL BASIS OF GRAZING MANAGEMENT*
Authors: Spedding C. R. W. 
Published: April 2006

Grazing management should be firmly based on knowledge derived from studies of both animal‐ and plant‐physiology. It is essential to understand both the nutritional needs of the animal and the effect of harvesting procedures on the growth rate of the plant.Animal performance, however, is not simply related to the mean nutritive value of the sward on offer; selective grazing can result in large differences between the latter and the value of the diet actually consumed. Thus it is possible to obtain similar animal growth rules on very different pastures, where grazing pressure is very low, or to obtain different animal performances on pastures which differ little in mean digestibility, but where the herbage is more, or less, ‘available’. It is therefore necessary to understand the relationship between the amounts of herbage on offer, removed and left behind in grazing, and the nutrient intake of the animal.To use biological criteria, such as the quantity of herbage present, in operating grazing methods it is essential that they are expressed in terms which are relevant theoretically and measurable in practice.The results of experimental comparisons of managements can not necessarily be used to judge the usefulness of physiological concepts, since the assumption that such concepts are embodied in the managements is often unjustified. There is, for example, little evidence that continuous and rotational grazing, under conditions of ‘correct’ stocking, result in different frequencies of defoliation of the individual plant units involved.
A COMPARISON OF NUTRIENT LOSSES IN BALED HAY MADE FROM FORAGE‐HARVESTED, CRIMPED OR TEDDED SWARDS WITH THOSE IN BARN‐DRYING
Authors: Kerr J. A. M. , Brown W. O. 
Published: April 2006

Two experiments were conducted to study the effect on nutrient loss and feeding value of making hay by different means, using a barn‐drier, a forage‐harvester, a crimper and conventional tedding. Both forage‐harvesting and crimping of the herbage significantly increased the rate of drying, compared with tedding alone. In Exp. 2 this effect enabled the crimped and forage‐harvested hays to be baled for storage 3 days earlier than the tedded hay. The use of the forage‐harvester significantly reduced the yield of herbage compared with conventional mowing. Nutrient losses from cutting until storage were highest for the forage‐harvested hays, the loss of dry matter between cutting and storage in the forage‐harvested hays being 39·9 and 19·3%, respectively, in Expt 1 and 2 with corresponding losses in the conventionally made hays of 7·1% and 9·3%. Crimping the hay resulted in higher nutrient losses than tedding. In Expt 2 there was a loss of dry matter of 17·5% in the conventionally made hay during an 18‐week storage period, compared with 3·6% in barn‐dried hay, 10·8% in forage‐harvested hay and 8·8% in crimped hay.In Expt 2, in which digestibility determinations were made, conservation decreased the total digestible nutrients and starch equivalent in all treatments. The use of the barn‐drier gave the most efficient conservation of total digestible nutrients, followed by the crimped, forage‐harvested and conventional treatments in that order. The starch equivalent values of hays made from the same sward were 43·0 when barn‐dried, 39·8 when crimped, 38·6 after forage‐harvesting and 31·6 after tedding.
THE ENERGY RETENTION OF LAMBS GRAZING S37 COCKSFOOT, S23 RYEGRASS AND S24 RYEGRASS AT LOW GRAZING PRESSURE
Authors: Milfokd R. , Minson D. J. 
Published: April 2006

A grazing experiment to measure the feeding values of 4‐week‐old regrowths of S37 cocksfoot, S23 ryegrass and S24 ryegrass is described. A low grazing pressure was maintained on the pastures to ensure that animal production was not limited by herbage availability. Each sward was grazed by a group of 12 lambs under “worm‐free” conditions. Increases in empty body weight, dry body weight and energy were measured by the comparative slaughter technique.The liveweight gain of the cocksfoot‐fed lambs was the same as the ryegrass‐fed groups during the first half of the experiment but was lower in August and September. The final liveweight gains on S23 and S24 ryegrass were 14% higher than on S37 cocksfoot, but in terms of energy retention S23 ryegrass was 18% and S24 7% better than S37 cocksfoot. Digestibility measurements of herbage cut from the plots being grazed showed a positive correlation with energy retention by the lambs. Energy retention was negatively correlated with the proportion of acetic acid in the rumen adds, a fraction which was itself correlated with the soluble carbohydrate content of the herbage, but not with the digestibility of the herbage.When interpreting animal‐production results, intake, digestibility and rumen volatilc‐fativ‐acid proportions, should be taken into account. Because of the inadequacy of present methods of estimating the herbage intake of grazing animals, measurement of body‐energy gains is not justified and empty‐liveweight gains are sufficiently precise to measure relative energy retentions at pasture.
BREEDING AND BLENDING*
Authors: Rogers H. H. 
Published: April 2006

The grass breeder's approach to the problem of producing new varieties is related to factors controlling sward production. Those factors under the control of the breeder, especially plant type and management, are considered in more detail.It is argued that the methods used by the breeder produce seed of predictable performance when grown under a defined set of conditions‐climate, soil and, above all, management. The fate of this ‘improved’ seed is considered in relation to the multitude of seeds mixtures prescribed today. Large imports of seed are made annually into the U. K. but bred strains account for only a low percentage of the herbage seeds used.Some results from Cambridge trials are presented to show the effects on sward production of plant density, seed size, depth of sowing, cutting treatments and the mixing of genotypes. It is suggested that these results point to the frequent misuse of bred strains, both in blending and in the quantity of seed recommended per unit area.The future prospects for herbage breeding are discussed and some novel ideas of cropping mentioned which may, to a limited extent, supplement the use of herbage seeds.
THE INFLUENCE OF VARIOUS FORMS OF NITROGENOUS FERTILIZER ON THE GROWTH OF A PERENNIAL RYEGRASS / WHITE CLOVER SWARD IN EARLY SPRING
Authors: Cowling D. W. 
Published: April 2006

The effect of 4 or 5 forms of nitrogenous fertilizer on the yield and botanical composition of a perennial ryegrass/white clover sward was examined in 3 different years. The uptake of N by the grass was also estimated. Ammonium nitrate (as Nitro‐Chalk), ammonium sulphate and urea gave similar yield increases, although in one year, when high rainfall followed the application of fertilizer, urea was slightly inferior. Gas liquor gave variable responses in the 3 years. Nitroform, a urea‐formaldehyde, was generally less effective than the other forms of fertilizer. The uptake of N from Nitro‐Chalk, sulphate of ammonia and urea did not vary greatly from year to year although the uptake of soil N by the untreated control did.Response to N in the yield of dry‐matter varied from year to year. This variation was due partly to differences in the amount of clover present and partly to differences in the extent to which N taken up by the grass was used for the synthesis of dry‐matter.The white clover content of the sward was not greatly reduced in spring by the application of the fertilizer, and there were no consistent differences between the effects on clover of the forms of the fertilizer. A reduction was apparent in the summer but not in the autumn.It may be necessary to increase replication above the level of 3 to 6 which is frequently employed in field experiments if more precise quantitative estimates of response and of the relative efficiency of various forms of nitrogenous fertilizer are required.
CROPPING SPARTINA SALT MARSH FOR SILAGE
Authors: Hubbard J. C. E. , Ranwell D. S. 
Published: April 2006

About half an acre (0·40 ha) of the salt marsh grass Spartina townsendii (s. l.) was cut from a Bristol Channel marsh using a small tractor modified for use on estuarine marshland. The cut grass was ensiled with molasses in a plastic silo.Chemical analyses were carried out on samples of fresh grass and silage. Silage was fed ad libitum to Halfbred × Suffolk wether sheep. Intake, digestibility values and crude protein content were similar to those of medium quality hay.
WHITE CLOVER AND HILL LAND IMPROVEMENT
Authors: Munro J. M. M. , Hughes Roy 
Published: April 2006

As a preliminary step in the development of improved bred varieties an examination has been made of the factors which contribute to the success or failure of white clover (Trifolium repens) in hill land reseeding. Severe restrictions are placed on clover performance and N fixation in many hill areas in Britain by the poor climate, the low pH and exchangeable base status of the soils and the low frequency of effective indigenous Rhizobium strains.Agronomic solutions to some of these problems exist, but experience in mid‐Wales suggests the need for new bred varieties with improved adaptation to the prevailing conditions, particular attention being directed to the limitation of N fixation by low soil temperature.
A COMPARISON OF THE REACTION OF DIFFERENT GRASS SPECIES TO FERTILIZER NITROGEN AND TO GROWTH IN ASSOCIATION WITH WHITE CLOVER. II. YIELD OF NITROGEN
Authors: Cowling D. W. , Lockyer D. R. 
Published: April 2006

Seven species or varieties of grass, and a mixture of 3 of them, were sown in pure swards, treated with 4 levels of nitro‐chalk (0, 17·5, 35, and 70 Ib N/ac/cut) and cut 4 or 5 times each year. Each species and the mixture were also sown with white clover, and the effect of fertilizer N on the yield of N in each grass was compared with the effect of clover on the yield of N harvested from the grass/clover swards.The regression line for response in yield of N with increasing levels of fertilizer N showed slight, but significant, upward curvature. The grasses differed in their uptake of N from the soil, S37 cocksfoot and S48 timothy showing relatively high uptakes, and the ability of each grass to take up fertilizer N was usually related to its uptake of N from the soil. Differences in the yield of dry matter between the species, at a similar level of N, are discussed, and it was concluded that perennial ryegrasses were most efficient and Agrostis tenuis was least efficient in using the N taken up in the production of DM.In general, there were no significant differences between the yields of N of the grass/clover mixtures; the N yields of the grass components were significantly different and tended to be inversely related to the N yields of clover.Grasses which gave high yields of N with fertilizer were also high yielding when grown in association with clover. Pure grass swards required more than 200 Ib fertilizer N/ac/yr in order to yield the same amount of N as the grass/clover swards. The amount of N estimated to have been derived by grass from clover (indirect effect of clover) increased each year; it was highest with S37 cocksfoot and lowest with Irish perennial ryegrass, averaging 46 and 23 Ib N/ac/yr, respectively.
ABSORPTION OF RADIO–ACTIVE PHOSPHORUS FROM TAP–AND NODAL ROOTS OF WHITE CLOVER (TRIFOLIUM REPENS L.)
Authors: Ueno M. , Williams R. Dorrington 
Published: April 2006

Absorption by the tap‐root and by different nodal roots of white clover S100 and translocation of 32P were investigated to find to what extent nodal roots can compensate for the absence of a tap‐root. 32P absorbed from the tap‐root was distributed evenly within the whole plant. When translocation from the 2nd and 7th nodal roots was studied, similar distribution was obtained only from the nodal root closer to the centre of the plant. The backward movement of 32P absorbed from nodal roots at the base of the plant increased as the root size increased. Removal of tap‐roots resulted in temporary depression of translocation; its effect disappeared within 3 weeks.It is concluded that the ability of nodal roots to compensate for loss of the tap‐root depends on their position and size.
THE EFFECT OF LEVEL OF NITROGEN FERTILIZER ON BEEF PRODUCTION FROM GRAZED PERENNIAL RYEGRASS/WHITE CLOVER PASTURES
Authors: Alder F. E. , Cowlishaw S. J. , Newton J. E. , Chambers D. T. 
Published: April 2006

In a 3 × 3 factorial experiment, the effects of three levels of nitrogenous fertilizer (0, 336 and 672 kg/N per ha) and three grazing intensities on live‐weight gains and carcass attributes were measured.The live‐weight gains of the animals (per head) over the season were greater at the low and moderate grazing intensities than at the high; this effect occurred mainly from July to October each year. Gains were low on the no‐nitrogen swards from July 1962 to the end of the grazing season and throughout 1963: this was related to the very high clover content of the swards.In all years, as grazing intensities increased, the carcass weights per animal became lower. Carcass balance, carcass length, depth of longissimus dorsi muscle, fat thickness over the longissimus dorsi, weight of kidney suet and channel fat, and weight of the alimentary tract also reflected the effect of treatment on weight gains.The results are discussed in relation to the botanical composition and consumption of the herbage, presented in Part I.
NITROGENOUS FERTILIZATION OF ITALIAN RYEGRASS IN SPRING
Authors: Heddle R. G. 
Published: April 2006

A series of experiments in eastern Scotland, carried out over a 7–year period, on the application of N fertilizers to Italian ryegrass for producing early spring grass, indicated that maximum yields are likely to be produced if the fertilizer is applied not later than the middle of March in most seasons. Only rarely did application in February result in a loss of N and in reduced herbage yields. Italian ryegrass appears to be able to make some growth at temperatures below 40†F.Increasing the rate of N application resulted in increased DM yield, the response averaging 9–4 lb DM per lb N. Herbage N concentration was increased by the additional N fertilizer. Nitro–chalk and ammonium sulphate were equally effective in producing early grass, irrespective of application date.
THE INFLUENCE OF THE QUANTITY OF HERBAGE OFFERED AND ITS DIGESTIBILITY ON THE AMOUNT EATEN BY GRAZING CATTLE
Authors: Hodgson J. , Wilkinson J. M. 
Published: April 2006

Six calves, six heifers and six dry cows grazed a mature sward (treatments A and B) and a leafy aftermath (treatment C) in succession. The yields of herbage on the two swards were 7100 lb and 1950 lb DM per acre (7950 kg and 2180 kg per ha), respectively. The amounts of herbage offered daily were 47 lb (21–5 kg) DM per head (treatment A), 70 lb (32 kg) (treatment B), and 60 lb (27 kg) (treatment C), Two estimates of herbage organic–matter intake (O,M,I,) were made on each treatment; records of grazing behaviour were made on treatments B and C, The digestibility of the diet selected on treatment C was higher than that selected on treatments A and B, and the animals ate significantly more O,M, on treatment C, The total grazing times on treatments B and C were similar, but the animals found it more difficult to graze on treatment BHerbage O.M.I. increased significantly from treatment A to treatment B, even though the quantity of herbage offered per day on treatment A greatly exceeded the amount eaten. The increase in O,M,I, was found to be associated with an increase in faecal 0,M, output, but the digestibility of the diet did not change.
THE EFFECTS OF LEVEL OF NITROGEN FERTILIZER ON BEEF PRODUCTION FROM GRAZED PERENNIAL–RYEGRASS/WHITE–CLOVER PASTURES
Authors: Alder F. E. , Cowlishaw S. J. , Newton J. E. , Chambers D. T. 
Published: April 2006

The treatments in this summer–grazing experiment were designed as a 2 × 3 factorial, there being two levels of nitrogenous fertilizer (nitro–chalk), supplying 0 and 336kg of N/ha per annum (NO and N3, respectively) and three stocking rates. The fertilizer was applied in 7 dressings at approximately three–weekly intervals. The animals used were Hereford x Friesian steers; these were slaughtered at the end of the grazing season. The stocking rates were calculated on the basis of expected herbage production. The experiment was laid out in 6 randomized blocks which were grazed in rotation. Two blocks were cut for conservation before grazing each year; up to the end of June only 4 blocks were used for grazing.There was little contamination of the swards with unsown species. With the NO swards the clover contents declined each year, but remained fairly high at over 20% in 1965. Clover contents also declined each year in the N3 swards and by 1965 were only 2 to 4%.The quantities of herbage cut for conservation were higher from the swards receiving N. The live–weight gains of the cattle (per head) were higher at the lower stocking rates, the effect of stocking rate being more noticeable in the July to Oct. period. Live–weight gains per ha increased at the higher stocking rates. In 1963 and 1965, as stocking rates increased carcass weights per animal decreased and carcass quality, as indicated by the commercial grades, was poorer. In 1964, a dry spell from July to Oct. necessitated the removal of cattle from the experiment and the effects of treatment on carcass weight and quality were not apparent.
PEDOMETER MEASUREMENTS OF THE DISTANCE WALKED BY GRAZING SHEEP IN RELATION TO WEATHER
Authors: Powell T. L. 
Published: April 2006

During the winter months of 1963 and 1964, mature non–pregnant Clun Forest ewes at pasture were equipped with pedometers to study the value of these instruments for measuring distances walked, and to investigate the importance of weather on the distances travelled. Approximately 80 periods were recorded, each of about 24 hours. The accuracy of the measurements was checked by using a rangemeter and it was found that the reliabihty of pedometer records must be assessed on the animal from which they are obtained. The individual characteristics of the pedometers and/or the sheep gave rise to inaccurate records from about 50% of the instruments studied.Multiple regression analysis of data for each of the three sheep which provided suitable records revealed that, in dry weather, the average distance walked per hour of recording period increased signiJBcantly with mean air temperature in one case and with hours of bright sunshine in another. Wind–speed effects were unimportant. The distance walked by all three sheep increased significantly with hours of daylight per recording period, and this was the only variable found to affect distance walked in wet weather. Differences between average distances walked per hour under dry–and wet–conditions were non–significant.It is concluded that for measuring the distances walked by sheep, the disadvantages of the pedometer outweigh its advantages.
THE GROWTH AND DEVELOPMENT OF SOME GRASS SPECIES UNDER COMPETITIVE STRESS
Authors: Rhodes I. 
Published: April 2006

Three experiments were carried out in a semi‐controlled glasshouse environment to determine the response of individual plants to competition; (i) between seedlings of different species, (ii) between seedlings derived from seeds of differing sizes within a species, and (iii) between seedlings and established plants.Differences were detected in seedling competitive ability between species and between plants derived from differing seed sizes. In associations of species of very high and very low competitive ability the differences in competitive ability were accentuated by an increase in plant density.Established plants of Phalaris coerulescens were less aggressive to seedlings growing in close proximity than were plants of Lolium rigidum and H1 ryegrass. Despite the early death of established swards of L. rigidum, and the consequent removal of competitive stress, there was no rapid increase in the growth and development of seedlings in these swards. Possible mechanisms causing this effect are discussed.There was evidence of a specific relationship between the species of the established sward and the seedling species, in particular seedlings of HI ryegrass were particularly susceptible to competition from established plants of their own species.Dry weight per plant, tiller production, rate of leaf appearance and leaf size were ail affected by competition between seedlings; however, tiller production was generally more severely affected than rate of leaf appearance and leaf size.Dry weight per plant, tiller production, seedling height, number of leaves per tiller and number of seeds per seedling were all affected by competition from established plants.
THE EFFECT OF STOCKING RATE AND SUPPLEMENTARY CONCENTRATE FEEDING ON MILK PRODUCTION
Authors: Castle M. E. , Drysdale A. D. , Watson J. N. 
Published: April 2006

The effect of stocking rate and of feeding a supplement of barley on milk yield and quality was studied in an experiment with 18 spring‐calved Ayrshire cows grazing from early May until early September in 1964 and 1965. Three treatments were compared: (A) grazing at a normal stocking rate with no supplements fed (the control); (B) grazing at a high stocking rate with no supplements fed; (C) grazing at a high stocking rate, as on treatment B, with a supplement of 8 Ib rolled barley per cow daily. On treatment A, 0.92 ac/cow was used for grazing, plus some conservation, and on treatments B and C, 0.70 and 0.58 ac in 1964 and 1965, respectively. The average daily milk yields were 35.4, 32.9 and 37.0 Ib (16.1, 14.9 and 16.8 kg), respectively, on treatments A, B and C in 1964, and 39.1, 32.3 and 38.8 Ib (17.8, 14.7 and 17.6 kg) in 1965. Milk production/ac was 24 and 32% higher on treatment B than on treatment A in 1964 and 1965, respectively.The response to the barley feeding on treatment C was equivalent to an extra 1 gallon milk from 20 Ib barley in 1964 and from 12 Ib barley in 1965 (10 litres of milk from 20 and 12 kg barley). The total‐solids content of the milk from the three treatments was not significantly different. It is concluded that, at the present price of barley and the price received for milk, an increase in stocking rate, with a consequent increase in the milk yield per acre, was more profitable than feeding barley.
FERTILE TILLER PRODUCTION AND SEED YIELD IN MEADOW FESCUE (FESTUCA PRATENSIS L.)
Authors: Lewis J. 
Published: April 2006

The seed‐producing capacity of two varieties of meadow fescue, S215 and S53, sown at three different spacings, was compared. One level of nitrogen was applied on three different dates in the spring. Tiller counts were made periodically during the growth of the crop. Fertile‐tiller production was found to be related to vegetative growth.The varieties differed not only in yield, but also in growth dynamics. A larger percentage of overwintering shoots became fertile in the hay variety, than in the pasture variety.Drill spacings had significant effects on plant establishment and on vegetative‐and fertile‐tiller numbers. In both years N applied in March gave the highest production of fertile tillers. Date of N application did not produce marked trends in yield. The influence of spacing and date of N application on the number and density of spikelets indicated that the plant adjusted itself to environmental factors. Thus spikelet numbers were reduced in early heads with narrower drill spacing and with late applications of N. Head emergence was earlier in narrow drills, but time of N application in the spring did not produce significant differences in this respect.