bluuebunny/crossref_metadata_2025 huggingface dataset:
A Fuse Survey of Disk-Accreting Cataclysmic Variables
Authors: Froning C. S. , Long K. S. , Szkody P. , Gänsicke B. T.
Published: June 2019

We present initial results of a survey of the FUV spectra of disk-accreting cataclysmic variables obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE).

FUSE covers the 905 - 1188 Å range at spectral resolutions ≃0.1 Å. To date, FUSE has observed more than 65 cataclysmic variables (CVs). Publicly-available data include observations of 11 dwarf novae (DN), 15 non-magnetic novalikes (NLs), 7 intermediate polars and DQ Her stars, at least 15 polars, and 4 super-soft X-ray binaries.
Spectroscopy of Old Nova Candidates
Authors: Schmidtobreick L. , Tappert C. , Bianchini A. , Mennickent R. E.
Published: June 2019

We present optical spectroscopy for several old nova candidates that hitherto lacked such observations. V842 Cen, V630 Sgr, XX Tau, CQ Vel, and V840 Oph show typical CV spectra, but V529 Ori is probably misclassified.

V630 Sgr is an eclipsing system with an orbital period of 2.83 h. In spite of the high inclination, the emission lines are not, double-peaked at the resolution of 1 mm.
Jovian Dust Bursts
Authors: Zook H. A. , Grün E. , Baguhl M. , Hamilton D. , Linkert G. , Liou J.-C. , Forsyth R. , Phillips J. L.
Published: June 2019

Six streams of dust were unexpectedly detected by the Ulysses dust detector while this spacecraft was approximately within one AU distance from Jupiter (Grün et al., 1993). Stream durations ranged from hours to days for individual streams. It was clear that the dust in these streams (or bursts), from their directionality of approach to the spacecraft and from the nearness of stream occurrences to Jupiter, emanated from the Jovian system.

Following the original report, Baguhl et al. (1994) later relaxed the criteria for differentiating true dust impacts from “noise pulses” and found almost triple the number of dust impacts in the six streams already found. They also found 5 more streams that, except for one stream, clearly emanated from the Jovian system. The criteria were relaxed in such a way as to not introduce “noise events” into the data.
The Physics of Meteors
Authors: Ceplecha Z.
Published: June 2019

Interaction of a meteoroid penetrating the atmosphere can be described through its motion, ablation, luminosity, ionization and the geometry of its trajectory. A theoretical description may be based on the so called “single body theory”, generalized to allow for discrete fragmentation. Such a concept is fully able to simulate the motion and ablation (mass loss) of meteoroids from millimeter to meter sizes recorded through photographic techniques (the best precision of such observations is better than ±10 m in observed heights). Observed distances and heights as a function of time can be fit to this model with the intrinsic precision of the geometrical data. The majority of meteoroids follow the “single-body theory” closely: large values of the ablation coefficients derived from observations favor continuous fragmentation under very low dynamical pressures as the main process of ablation. The rest, some 20 to 30%, can be described by one or more discrete fragmentation points in addition to continuous fragmentation. Dynamic pressures at these grossfragmentation points are also very low, if compared with the strength of stony meteorites.

On the other hand, luminosity and ionization are not as well understood. Existing detailed spectral records show mostly radiation in form of emission lines of ablated meteoroid material with excitation temperatures in the range of 3000 to 5000 K. Additional theoretical modeling is called for.

Photographically documented meteorite falls can be used for computation of luminous efficiencies, because the terminal mass and bulk density are known in these cases. Recently, photographs of the Lost City meteorite fall were remeasured with special attention to visible trails of fragments. The new analysis revealed two main discrete fragmentation points that are in perfect agreement with the geometrically resolved trails based on the dynamics. Moreover, Adolfsson (1996) found an artificial periodic signal originating from the switching shutter and after removing this signal, he was able to find an initial rotation period of 3.3±0.3 s and also the rotation phase of the Lost City meteoroid. A solution for the motion, ablation and rotation of the Lost City meteoroid is now completely self-consistent throughout the whole photographed trajectory and yields an initial mass of m = 163 ± 5 kg. The luminous efficiency was found to be 6.1% at v = 13 km/s (for 4500 K), this is ∼ 10x larger than the values determined from artificial meteors, i.e., from masses of 1 g fired downward from high-altitude rockets by shaped-charge.
The Meteoroid Orbit Facility AMOR: Recent Developments
Authors: Baggaley Jack W. , Bennett R.G.T.
Published: June 2019

Some 3 x 105radar meteoroid orbits have been secured to date by the AMOR, project since its inception in 1990. For many types of study it is important to realize a high angular resolution; for example to probe more incisively meteoroid stream orbital structure in order better to determine the rôle of the various processes controlling stream dynamics. The orbital precision of AMOR has been enhanced by developing a new dual spacing interferometer using single channel phase detection. In addition, a Doppler-sensing facility has been incorporated to record simultaneously data concerning middle atmospheric dynamics allowing better interpretation of the individual echo signals.
On the Determination of Velocities of Radar Meteors
Authors: Pecina P.
Published: June 2019

The results of testing the classical method of velocity determination based on the positions of the extrema of Fresnel diffraction patterns (FDP) in radio echo amplitude, is presented. This technique is compared to the method of nonlinear least squares fitting (NLSF) of the theoretical patterns to the observed those. It is shown that while the classical method can fail in yielding correct values for the velocity of radar meteors, the NLSF method always yields good results.
A New Technique for Radar Meteor Speed Determination: Inter-pulse Phase Changes from Head Echoes
Authors: Taylor A.D. , Cervera M.A. , Elford W.G. , Steel D.I.
Published: June 2019

We have implemented a 54 MHz radar located near Adelaide, South Australia, for novel forms of meteor observation. Here we describe a radically new form of meteor speed determination: we measure the rate of phase change for head echoes obtained from meteors propagating down the beam towards the radar. These not only provide speeds of unprecedented precision, but also deliver accurate deceleration measurements, these being of importance in understanding the meteoroid ablation process and exploring the physical parameters of such bodies.
No Meteor Storms Expected from P/Machholz 2
Authors: Asher D.J. , Steel D.I.
Published: June 2019

P/1994 P1 Machholz 2 is the first Earth-crossing shortperiod comet to have been observed to have split since 3D/Biela about 150 years ago, and that fragmentation resulted in the Andromedid meteor storms of 1872 and 1885. Thus a pertinent question is whether meteor storms might result from P/Machholz 2 in the foreseeable future. Here we integrate its orbit to ascertain when the node might next occur near a heliocentric distance of 1 AU, and find that this is not anticipated far over 1000yr, although some meteor activity in ∽300yr is possible. On such time-scales the recently-released debris will have dispersed, so that meteor storms are not expected from this comet.
Concepts for Dust Velocity Measurements on a Cometary Orbiter
Authors: Perruchot Sandrine , Lamy Philippe L. , Giovane Frank , Gustafson Bo Å. S.
Published: June 2019

We have studied several optical systems for dust velocity measurements on a cometary orbiter using light scattering to detect particles. Two main concepts are considered. The first relies on trajectory imaging, while the second uses time-of-flight measurements between two or more light sheets. Their merits and disadvantages are discussed. The favored system, time-of-flight between two planes with particle localization, is described.
The Elemental Composition of Interplanetary Dust
Authors: Brownlee D.E.
Published: June 2019

Analyses of recovered samples of interplanetary dust have provided direct data on the bulk elemental composition of interplanetary dust over the 5μm to 1mm size range. The majority of particles have compositions similar to the bulk composition of chondrites although C and some trace volatile elements are often found in excess of CI abundances. Some individual particles have distinctly non-chondritic compositions. In most cases these particles contain large mineral grains.
The Search for Interstellar Components in Interplanetary Dust Particles
Authors: Bradley John , Ireland Trevor
Published: June 2019

Amorphous silicate grains known as GEMS have been found in chondritic porous interplanetary dust particles (IDPs) from comets. GEMS are composed of nanometer-sized FeNi metal and Fe-rich sulfide crystals embedded in silicate glass. The properties of GEMS appear to have been shaped primarily by exposure to ionizing radiation and, since the irradiation occurredprior toaccretion of the cometary IDPs, GEMS may have formed either in the solar nebula or presolar interstellar environments. The sizes, shapes, structures, and compositions of GEMS correspond to those of interstellar “amorphous silicate” grains. Nanometer-sized superparamagnetic metal inclusions dispersed throughout GEMS provide a logical explanation for alignment of interstellar silicate grains in the galactic magnetic field. Irrespective of their origins, GEMS are an important class of submicrometersized chondritic objects. If they were formed in the solar nebula, then they are among the oldest known solar nebula solids. If they are presolar, then they are probably examples of the “amorphous silicate” grains which are ubiquitous throughout the interstellar medium.
COBE Observations of Zodiacal Emission
Authors: Hauser Michael G.
Published: June 2019

The COBE Diffuse Infrared Background Experiment has obtained some of the most extensive observations of the interplanetary dust (IPD) cloud ever assembled. For the 10 months of cryogenic operation, the brightness of the entire celestial, sphere was mapped with an 0.7° x 0.7° field of view at wavelengths of 1.25, 2.2, 3.5, 4.9, 12, 25, 60, 100, 140, and 240 μm, and the linear polarization was mapped at 1.25, 2.2, and 3.5 μm. Observations with reduced sensitivity continued at all wavelengths short of 12 μm for over 3 years after cryogen expiration. Throughout these observations, nearly 1/2 of the sky was mapped every day at elongation angles ranging from 64° to 124°. I describe the DIRBE and the general character of the infrared sky, outline the DIRBE team's approach to isolating the IPD signal, and review results of our initial studies of the zodiacal dust bands, the circumsolar dust ring, and the character of IPD cloud particles.
Zodiacal Light - Scattered Fraunhofer Line Profiles
Authors: Clarke David
Published: June 2019

The scattering function of Hong's successful model for the brightness variation with elongation, B(ε), of the Zodiacal Light has been used to calculate profiles of Doppler shifted Fraunhofer lines. Substantial line shape changes with ε are predicted with an indication of a bifurcation at ε < 30°, so offering an explanation for reported F corona observations.
Model Calculations of Near Solar Dust Properties
Authors: Mann I. , Ishimoto H. , Okamoto H. , Mukai T.
Published: June 2019

We discuss efforts to explain the dust distribution, as it was derived from the F-coronal brightness, mainly how to explain a constant number density near the Sun. It is shown that silicate particles have temperatures below the blackbody temperature if the impurity from absorbing material amounts to less than 0.1% in volume. This effect is especially significant for porous particles and may explain why particles can approach to less than 3 R⊙ from the Sun. Another effect may arise from particles on high eccentricity orbits and from the influence of collisional fragments. Whereas on the one hand heat resistant silicate particles may cause a stable dust cloud in the solar vicinity, on the other hand dynamical effects may cause a variation of the number density in the corona in short time scales.
Laboratory Experiments on Carbonaceous and Silicate Materials
Authors: Colangeli L. , Mennella V. , Rotundi A. , Bussoletti E. , Palumbo P.
Published: June 2019

Ground-based, remote and “in situ” observations show that dust plays an important role in the evolution of interstellar, circumstellar and interplanetary media. Despite the wealth of available astronomical data, a main item to be clarified concerns the actual chemico-physical composition of cosmic dust. A correct interpretation of observations must rely on a systematic comparison with results coming from laboratory simulations. In this paper we present an overview of recent results, obtained in our laboratory, on various forms of carbon-based and silicate grains of possible astrophysical interest.
Measurement of Dust Electric Charges by the Ulysses and Galileo Dust Detectors
Authors: Svestka J. , Auer S. , Baguhl M. , Grün E.
Published: June 2019

The Galileo and Ulysses dust detectors can detect electric charges of dust particles. Dust particles entering the sensor (see, e.g., Grün et al. 1992) may be detected by the charge Qp that they induce to the charge grid. All suitably massive dust particles - charged or uncharged - are then detected by the cloud of ions and electrons they produce during the impact on the hemispherical target after the time of flight between the charge grid and the target. After separation in the electric field, ions and electrons are collected by separate electrodes and produce two pulses of opposite polarity. From the two pulse heights and the rise times, the mass and impact speed of the dust particle are derived.
Dust Evolution in Protoplanetary Disks
Authors: Henning Thomas , Schmitt Wolfgang , Klahr Hubert , Mucha Rastislav
Published: June 2019

The evolution of dust particles in circumstellar disk-like structures around protostars and young stellar objects is discussed. We especially consider the coagulation of grains due to collisional aggregation and the influence of this process on the optical properties of the particles. These dust opacities are important for both the derivation of the circumstellar dust mass from submillimetre continuum observations and the dynamical behaviour of the disks.

We present first results of a numerical study of the coagulation of dust grains in a turbulent protoplanetary accretion disk described by a time-dependent one-dimensional (radial) “alpha” model. The influence of grain opacity changes due to dust coagulation on the dynamical evolution of a protostellar disk is investigated. In addition, we consider the grain motion in two-dimensional disks.
Central nervous control of voluntary food intake
Authors: Forbes J. M. , Blundell J. E.
Published: June 2019

The central nervous system is the integrator of most of the actions of the animal and as such plays a vital rôle in the control of voluntary food intake. Much of the work to understand how intake is controlled has been carried out with rats but that which has been done with pigs is included. The first experiments used electrolytic lesions in the designation of the ‘hunger centre’ and the ‘satiety centre’. Recent work has identified the paraventricular nucleus as a sensing site for experimental manipulations. Chemical stimulation of the brain has also been carried out to try to gain understanding of the rôle of neurotransmitters. Noradrenaline (NA) stimulates intake when given into many sites. Serotonin (5-HT) inhibits intake and has been claimed to play a rôle in the selection of macronutrients but 5-HT must now be interpreted in the light of the existence of several different subtypes of 5-HT receptors. Dopamine appears to moderate the hedonic response of eating. Numerous peptides are active in the brain where their rôle as neuromodulators may be quite different from their function in the periphery and at least three types of opioid receptors are implicated with kappa antagonists producing the most potent facilitatory effects. Neuropeptide Y and peptide YY produce massive orexigenic effects which readily overcome peripheral satiety factors. The brain cannot control intake in isolation. It receives inputs in the blood stream, such as glucose, as well as via the nervous system, both from the special senses and from visceral organs such as stomach, intestines and liver. Taste and olfaction are important in diet selection and a specific appetite for protein has been demonstrated in the pig.
2.4 Performance Monitoring of Animals, Using On-line Computers
Authors: Turner M. J. B.
Published: June 2019

Increasing importance is being put on quality control of livestock both from performance and marketing aspects. The breeding of superior stock relies heavily on progeny testing, first in small numbers and later in larger scale field trials. With commercial stock, emphasis is placed on the food conversion efficiency; health of the individual, flock or herd; the market requirement and the likely date of attaining market readiness. All these factors rely heavily on close monitoring of the performance of the stock. However, with increasing pressures for shorter working hours and greater responsibilities per employee, close monitoring is likely to diminish rather than increase, unless modern technology comes to the aid of the producer. Already, electronics have been making inroads in this area. The advantages of using electronics for animal weighing were first demonstrated in the early 70's (Smith and Turner, 1974). Interest has been slow to build up but now most farmers and manufacturers recognize the potential. However, despite using electronic weight indication, the process of animal weighing remains a manual operation involving at least one man, more often two or three. Despite advances in animal handling procedures, in most manual weighing exercises there is always a risk of injury to both stock and men. A system of weighing which removes this risk and reduces stress on the animal would be welcomed by the producer. Electronic aids for milk yield recording and egg production have also been under development for some years (Burgess, 1980; Anon., 1980) but will not be dealt with here. This paper will deal solely with the prospects for fully automatic weight recording of live animals and describe some of the results of work conducted by the National Institute of Agricultural Engineering at Silsoe.
3.2 Modelling Sheep Systems
Authors: Sibbald A. R.
Published: June 2019

At the Hill Farming Research Organization (HFRO), we have been modelling various components of sheep systems and we have also attempted to model, where a need was seen, whole sheep systems at different levels of organization. The sheep systems involved are of course pastoral grazing systems on hill or upland farms. The purpose of this paper is to briefly describe these models, to identify reasons for their existence and to outline some of the problems encountered in their construction.

Models have been constructed at HFRO to satisfy particular needs. They cover a spectrum of interests. There are those which are concerned with resource allocation and economic evaluation, those which are built in an attempt to develop more precise operational management procedures and those which describe biological mechanisms and processes which may be conceptual but which provide a better understanding of particular components of an animal production system.

The first model (Maxwell, Eadie and Sibbald, 1973) was built to provide answers to the economic questions “Is a particular level of investment in a hill sheep system a viable proposition in both the short and the long term?” and “How does the economic performance of this strategy compare with those of alternatives?”, alternatives being, for example, different levels and rates of flock build-up, with variations in the timing of investments. The model makes year-by-year calculations of cash flow and balance based on Gross Margin, taking account of capital invested, changes in variable costs, tax and interest rates. The Gross Margin is determined from price and cost data and from biological performance. The model also calculates overall economic performance, for a pre-selected project length, as Net Present Value and Internal Rate of Return, taking account of increased stock valuation. These results are used to compare alternative schemes with different rates of investment.
4.3 Integration with Management
Authors: Kilkenny J. B.
Published: June 2019

Three obvious statements but well worth repeating: “Computers are only an aid to summarizing information for use in assisting management decisions”; “Records are only of any use if they are used — they are not an end in themselves”; and “No point having sophisticated computerized management aids if the basic information is not available and if only decisions at a simple level are to be made”.

Amongst dairy and pig producers, the need for keeping records is well established and probably over 40% of all dairy cows and pigs in Britain are involved in an enterprise recording scheme. By contrast, all too few beef and sheep producers currently keep any detailed computerized records in an organized way. It is estimated that only about 2% of all commercial beef and sheep are involved in an enterprise recording scheme. Good basic records are an essential ingredient to any more sophisticated management aid because these need to be based on relevant reliable data for individual situations. The need to use computers and their value on the individual farm is dependent upon having sufficient information to make it worthwhile employing them. The sophistication of management aids required for enterprises will be determined by the level of recording already involved. It is obvious that the requirements for beef and sheep producers are at a much more basic level than for many pig and dairy producers.
Nutritional principles in utilization of waste and by-products
Authors: Ørskov E. R.
Published: June 2019

The increasing awareness of the potential use of by-products and the recycling of waste materials, etc., presents the nutritionist with new and interesting challenges. There are several reasons for this. First, that many waste and by-products, hereafter referred to as waste suitable for animal feeding, are produced in small quantities in differing localities; often availability is very seasonal and composition varies enormously. As a result there may be some reluctance both on the part of producers and government organizations to invest a great deal in a research programme of evaluation. Secondly, the motive of industrial producers for using organic wastes for animal feeding is more often a desire to obtain a positive return by selling wastes rather than paying for their disposal, than a real interest in meeting the requirements of the animals. As a result wastes are often produced with dangerous contaminants which could have been avoided.

In many instances, therefore, nutritional advice on the use of waste in animal feeding has to be based on a knowledge of similar known feeding-stuffs and a minimum amount of analysis for basic nutritional qualities and for possible dangerous contaminants. These statements are, however, generalizations as some material, like excreta, are of variable quality and produced in vast quantities. I shall attempt to discuss briefly the nutritional attributes of different classes of waste since they are to be discussed more in detail by others at this meeting. First, a division will be made into mainly nitrogen (N) and mainly energy-yielding products and secondly the feeding systems in which they can most profitably be used will be discussed.
The effects of increased prolificacy on lamb and ewe mortality in an intensive hill sheep system
Authors: Waterhouse A. , Logue D. N. , Roger L. C.
Published: June 2019

Increased prolificacy is often believed to increase the incidence of both lamb and ewe mortality especially in harsher environments. Fecundin® (Coopers Pittman Moore) is a vaccine which leads to immunization against androstenedione and a resulting increase in prolificacy (Rhind, 1987). The use of this drug gives a method of manipulating prolificacy without confounding any effects with improved nutrition, the most usual means of modifying reproductive success.

A programme was commenced in 1985 in which half the ewes in a flock of Scottish Blackface ewes was vaccinated with Fecundin (F), the remainder left unvaccinated (N). In subsequent years ewes were maintained on the same treatment. The data presented here are an analysis of a single age group of ewes completing a full lifetime on each treatment. Eighty-five ewes were allocated at random to each treatment. These were vaccinated in autumn 1985, given a booster vaccination 4 weeks pre-ram joining in 1986, 1987 and 1988 and sold as ‘cast for age’ after lamb weaning in 1989. With the exception of injection with Fecundin, at all times management was independent of treatment.
1.2 The Nature of Trace Element Problems: Delineating the Field Problem
Authors: Lewis Gwyneth , Anderson P. H.
Published: June 2019

By definition, the essential trace elements are required in very small amounts for optimum body function. The list of essential trace elements is steadily increasing, partly due to improved methods for the detection of very low concentrations and partly to the creation of experimental environments from which such elements can be excluded so that their essential properties can be demonstrated. However, this paper is considering field problems, and discussion will be limited to those elements which are known to be associated with disease in cattle and sheep. Pigs and poultry will be excluded because the major proportion are fed adequate amounts of the trace elements in compounded diets. In contrast, most of the sheep and a large proportion of the cattle population are heavily dependent on home-grown feeds, often only grass or grass products, and these animals are most at risk. Without supplementation, the intake of trace elements is dependent on the concentration in the herbage. It has been estimated that grassland provides almost three quarters of the total crude protein for ruminants in Britain and cereals provide another eighth. We must assume that home-grown feeds are a major contribution to animal diets.
3.1 Soil-Plant-Animal Interactions in Relation to the Incidence of Trace Element Disorders in Grazing Livestock
Authors: Thornton I.
Published: June 2019

The soil and its parent materials are the primary sources of trace elements on which soil-plant-animal relationships are built. It is important to recognize, however, that anthropogenic inputs of trace elements, in particular heavy metals from industrial and urban sources, may add to and at times exceed those from natural geological sources. Both deficiencies and excesses of trace elements can result in serious nutritional or toxicological disorders, while less severe imbalances may result in sub-clinical effects and, possibly, in production and fertility problems. Where obvious visual symptoms are absent, sub-clinical effects are frequently not recognized, although the areas affected are thought to be large and there are obvious economic implications. This paper examines the influence of soil and geological factors on trace element disorders in livestock, including interactions between natural and man-made sources of trace elements, and illustrates the applications of regional geochemical maps in predicting areas in which disorders are likely to be found.
6.6 Observations on the Variation in the Liver Copper Levels of Lambs
Authors: Adamson A. H. , Shaw W. B. , Dover P. A.
Published: June 2019

Observations were made, from 1970 to 1975, of the liver copper (Cu) levels of lambs reared on various feeding regimes and of lambs which were stillborn or died within the first 7 days of birth in what was considered to be a normal healthy flock.

Artificially reared Finnish Landrace × lambs were fed on reconstituted milk substitute and a concentrate containing 4 and 8 mg Cu/kg DM, respectively. Liver Cu levels were determined when lambs were slaughtered at 4/5 months of age. In one group, liver Cu levels varied from 500 to 1600 mg/kg DM without any evidence of Cu toxicity in any lambs, whilst, in another group, levels ranged from 50 to 600 mg/kg DM.
6.7 Erythrocyte Cu:Zn Superoxide Dismutase Activity and Hair or Fleece Copper Concentrations in the Diagnosis of Hypocuprosis in Ruminants
Authors: Suttle N. F. , McMurray C. H.
Published: June 2019

The conventional criteria of copper (Cu) status in ruminants, liver and blood or plasma Cu concentrations, show rapid reductions during depletion while the animal remains clinically normal. Criteria which change less rapidly in response to depletion might be more closely correlated with clinical and sub-clinical condition. Among such criteria are superoxide dismutase (SOD), which occurs as Cu- and Zn-containing enzyme in erythrocytes, and hair or fleece Cu. We have examined the temporal relationships between these different criteria of Cu status in two experiments, in which steers and lambs had been depleted of Cu, to assess their diagnostic value.
6.12 The Use of Copper Tablets to Supplement the Drinking Water of Cattle Grazing ‘Teart’ Pastures
Authors: Farmer Phyllis E.
Published: June 2019

A field trial was carried out to test the efficacy of proprietary copper (Cu) tabletst in preventing hypocupraemia in beef cattle grazing molybdenum (Mo)-rich pastures. This product is based on a specially formulated matrix, which is claimed to control the solubility product of inorganic metallic salts when the tablets are suspended in a plastic container in water troughs.
9.3 Seasonal Changes in Forage Protein Production on Kenyan Grasslands
Authors: Ottaro M. J. , Steinbach J. , Musangi R. S.
Published: June 2019

Pasture productivity was studied between August 1977 and July 1978 at five different sites in Kenya's mixed farming regions by harvesting sample plots every 2 months at a standard height (3-4 cm). The content (%) and yield (kg/ha/day) of digestible crude protein was calculated from the results of the proximate analysis using the equation: DCP (%) = 5 + 60 log CP - 0.33 CF. The results were subjected to standard methods of variance and covariance analysis using precipitation as the covariate, since rainfall yields differed considerably among sites and seasons.
The management and performance of beef cattle in the hills and uplands
Authors: Gurnett L. R. , Waterhouse A.
Published: June 2019

With no supplementary feed to cow or calf, a suckler cow can produce a calf of 330 kg at 1 year old worth about £380. At 2.5 cows per ha on an upland farm, the system can be self-sufficient for grass and silage. Overall production can be 820 kg live-weight gain per ha with the use of 250 kg N per ha. This is technically an efficient enterprise. It is also profitable, with a gross margin per ha in excess of £800.

Work at Liscombe, in parallel with other centres, has developed to establish minimum healthy diets for the suckler cow whilst producing healthy, fast growing calves. The cow must be fertile and have a long life, producing on average 10 calves. This involves the controlled management of the natural ability of the cow to put on weight quickly in the summer and take it off slowly in the winter.

The winter diet of the cow can vary from (1) restricted silage alone, (2) silage plus untreated straw, (3) untreated straw plus concentrate supplement, or (4) treated straw alone. As a result, the enterprise is very flexible.

On a hill farm, the cow has a major role to control pasture in a subordinate role to sheep. Because of her role in pasture control, a low margin per cow can be accepted as a direct contribution to sheep production.
The grazing ecology of hill and upland swards
Authors: Hodgson J. , Grant Sheila A.
Published: June 2019

The grazing ecology of hill and upland swards is discussed in terms of (a) the influence of sward characteristics (species composition; plant maturity and morphology; canopy structure) on the ingestive behaviour, diet selection and herbage intake of sheep and cattle, (b) the reciprocal influence of grazing activity upon the species balance of natural and sown plant communities and (c) the importance of plant responses in limiting the impact of variations in grazing managements upon the net rate of herbage production from sown swards. Emphasis is given to the importance of objective criteria of plant morphology and sward canopy structure both in understanding sward and animal responses to management manipulation and in applying the results of grazing studies in farming practice.
In vitro digestibility of tropical legumes: tannin content and relationship between determinations made using the Tilley and Terry and pressure transducer techniques
Authors: Barahona R. , Narvaez N. , Lascano C. , Merry R. J. , Morris P. , Owen E. , Theodorou M. K.
Published: June 2019

A significant portion of ruminant production in the tropics relies on the grazing of native grasses growing in acid, low-fertility soils. Under these conditions, animal production is generally limited by the low quality and availability of forage supply. The introduction of forage legumes into grazing systems is commonly accepted as a way to alleviate this problem. However, many of the tropical forage legumes adapted to acid soils and selected on the basis of good agronomic performance have limited feeding value. This could be associated with increased production of secondary metabolites such as condensed tannins (CT), which have the ability to bind and precipitate proteins, carbohydrates and other molecules (Mueller-Harvey and McAllan, 1992). High intake of CT by ruminants has been associated with depressed intake and reduced digestibilities of protein and cell wall of temperate (Barry and Duncan, 1984; Pritchard et al, 1988) and tropical (Carulla, 1994) forage legumes. However, more recent work showed that intake and digestibility of tropical legumes was not only influenced by CT concentration but also by cell wall content (Barahona et al, 1997). In the ongoing process of identifying legume germplasm for acid soils, the use of in vitro techniques has been of great benefit. Gas production methods have considerable appeal in this respect due to their ability to evaluate digestion kinetics and their potential to simulate digestion processes in the rumen. Pendong et al. (1996) using temperate forages, showed that the pressure transducer gas technique of Theodorou et al. (1994) could be used to assess digestible organic matter disappearance as well as fermentation kinetics. A similar assessment was undertaken in the current study in which the tannin contents and cell-wall characteristics of tanniniferous legumes from Colombia were determined and related using measurements made in laboratories in Colombia and the United Kingdom.
Comparison of in situ and in vitro gas production techniques to estimate rumen degradation characteristics of forages
Authors: López S. , Carro M. D. , Valdés C. , González J. S. , Ovejero F. J.
Published: June 2019

Quantitative expressions of the kinetics of digestion are needed to estimate more precisely the quantity and composition of nutrients digested from feeds and their subsequent efficiency of utilization by the animal (Mertens, 1993). Degradation kinetic parameters are estimated by fitting appropriate models to data resulting from the measurement of either the undigested residue or the fermentation end-products after exposure of the feed to digestion. Kinetic data can be collected using either in vitro or in situ procedures. The in situ porous synthetic fibre bag technique has been extensively used to describe the kinetics of feeds degradation in the rumen. Several in vitro gas production methods have been developed to assess fermentation kinetics. The aim of this work was to study the relationship between rumen degradation parameters of forages determined either by the in situ procedure or by the gas production technique and to evaluate the potential of gas production measurements to assess the extent of dry matter degradation in the rumen.
Prediction of the organic matter digestibility of forages in horses by the gas test method
Authors: Macheboeuf D. , Jestin M. , Andrieu J. , Martin-Rosset W.
Published: June 2019

In horses, forages account for the greatest proportion of the diet (Micol and Martin-Rosset, 1995). As a result, the energy value of forages has to be determined very accurately to meet the horse requirements. In the UFC system (Horse Feed Unit) proposed by INRA (Martin-Rosset et al., 1994), the energy value of forages is closely related to organic matter digestibility (OMD).

In ruminants, OMD has been related to the in vitro gas production after 24 h of fermentation of foodstuffs with rumen fluid (Menke et al., 1979). The prediction of OMD with the gas test method is less accurate than with the nylon bag method but better than prediction performed with in vitro method or from chemical composition of foods (Khazaal et al., 1993 and 1995).

In the UFC system, three routine methods have been performed by our laboratory and proposed by INRA to predict routinely OMD of foodstuffs. OMD can be predicted either from chemical composition (Martin-Rosset et al., 1996a), by a pepsin cellulase method (Aufrère, 1982; Martin-Rosset et al., 1996b) or by near infra-red spectrometry (NIRS) (Andrieu et al., 1996).

The gas test method was subjected to be adapted in horses for predicting OMD. The accuracy of the prediction with the gas test method was compared with the other routine methods.
Chemical and biological characterization of Mediterranean foods
Authors: Mills C. R. , Stefanon B. , Susmel P. , Pell A. N.
Published: June 2019

The most extensively used methods to characterize and predict nutritive values of forages are fibre fractionation according to Van Soest (Van Soest et al., 1991), in situ degradability (Ørskov and McDonald, 1979) and gas production (Menke and Steingass, 1988; Pell and Schofield, 1993). The aim of the present experiment was to establish whether these methods could be used to characterize Mediterranean foods.
Precision pig management – resolving conflicts by integrated solutions
Authors: Wathes C. M. , Schofield C. P.
Published: June 2019

Integrated management systems (IMS) for pig production are one means by which the industry will be able to meet tight product specifications while satisfying society's demands to reduce the environmental impact of livestock production. The systems are based on modern theories of process control that have been proven in other industries but have yet to be applied to pig production. The initial application will be growth of the finishing pig but other stages of production, e.g. the gestating sow, may also be managed using an IMS. In the longer term, control of environmental processes within pig housing may also be amenable to an IMS but will undoubtedly reveal – and provide the opportunity to resolve – the conflicts between financial and environmental pressures in modern pig production. Other applications are envisaged and include active control of pig behaviour as well as disease.
Salmonella and food safety – why it matters for the British pig industry
Authors: Armstrong Derek
Published: June 2019

The production and marketing of safe, wholesome pork, bacon, ham and other pork products is of paramount importance to British farmers, processors, retailers, food service companies and those that supply them. It is not possible to guarantee the complete absence of bacteria in meat production. Most bacteria found on meat are harmless, but some can cause foodborne disease. Control processes to reduce or eliminate food safety risks are applied to every stage of the production and marketing chain from the farm to the consumer.

Key approaches to reducing the risk of foodborne disease include: reduction of zoonotic pathogens in slaughter pigs; prevention of cross contamination during activities such as transport and slaughter; safe processing of foods underpinned by HACCP (Hazard Analysis Critical Control Point); safe handling and preparation of food in the retail and catering sectors, including the adoption of HACCP principles and effective enforcement; safe handling and preparation of food in the home and enhanced surveillance of foodborne disease to monitor effectiveness of controls.
The effect of docosahexaenoic acid supplementation of the maternal diet on the performance and behaviour of piglets
Authors: Edwards S.A. , Bulman C. , Breuer K. , O’Connell N.E. , Sneddon I.A. , Sutcliffe M.E.M. , Mercer J.T. , Rance K.A.
Published: June 2019

The objective of this experiment was to measure the effects of preand postnatal supplementation of sows with an algal source of docosahexaenoic acid (DHA) on the pre and post–weaning performance of their piglets. The experiment was of 2 x 2 factorial design, with DHA supplementation of the sow diet (3g DHA/kg feed) during the last 4 weeks of pregnancy and/or 4 weeks of lactation. There was a significant positive effect (P<0.05) of lactation DHA on weaning weight. Piglets from sows which had received DHA supplement in gestation were heavier throughout the post–weaning period than controls (P<0.05), as were piglets whose mothers received DHA in lactation (P<0.05). When age and weight at weaning were used as covariates in the model, the liveweight gain in week 1 and over the whole 26 day post–weaning period were significantly greater (P<0.05) for piglets from sows which had received DHA supplement in gestation. It is concluded that DHA supplementation of sow diets can improve piglet performance.
A comparative analysis of population characteristics of the competing progeny (within UK) of UK elite eventing sires and all competing event horses within the UK
Authors: Whitaker T C , Hill J
Published: June 2019

A greater understanding of the population characteristics of sport horse populations is required to enable potential breed improvement programmes to be formulated correctly and be effective in their outcomes. To date limited research has been conducted into the UK sport horse population.

A selected group of progeny (n=339) sired by elite eventing stallions was examined. In the context of this study elite sires were defined as those that were ranked 1-10 by total lifetime points won by competing progeny up to the end of 2000 (British Horse Database, 2000). Comparative analysis was undertaken between the selected group and all competing eventing horses in 2000 (n=9387) (British Horse Database, 2000). Data collected for both groups included, total lifetime points won at eventing and dressage and total lifetime money won at show jumping. Basic descriptive statistics were produced for each data set (Table 1). Product moment correlations were performed for all discipline areas (Table 2). Data transformation was applied using LOG+1(Hassenstein, Roehe, and Kalm, 1996).
Relationship between water holding capacity and fibre concentration in equine feeds
Authors: Hyslop J J , McLean B M L , Moore-Colyer M J S
Published: June 2019

The water content of feedstuffs is an important factor when considering both the nutritive value of a feed for dietary rationing purposes and when assessing the functional properties associated with the practical inclusion of a feedstuff in animal diets. Water is a vital nutrient in its own right and must be supplied on a daily basis. Feed associated water provides one source of this obligatory requirement. In addition, the water holding capacity (WHC) of a feedstuff and its relationship with other constituents of the feed may have important effects. Water can be associated with feedstuff in one of three ways (Robertson and Eastwood, 1981b). Firstly, water can be bound by the hydrophilic polysaccharides of the fibre component of feeds. Secondly, water can be held within the structural fibre matrix of feeds and finally, water can be associated with feedstuff fibre other than bound or matrix water and is usually considered as water trapped within the cell wall lumen.
The effect of particle size on volatile fatty acid profiles obtained from an alfalfa and unmolassed sugar beet pulp diet following in vitro incubation with equine faeces
Authors: Bice RKT , Moore–Colyer MJS
Published: June 2019

The equid has been estimated to derive 70% of energy from volatile fatty acids (VFA) production. Hind gut fermentation in the equid degrades structural carbohydrates to VFA's that are oxidised by the liver as a source of energy. Maximising this potential source of energy is an important consideration when attempting to improve the utilisation of fibre feeds by the equid. It is generally accepted that the acetate:propionate:butyrate are produced in a ratio of 76:18:5 by horses consuming forage diets (Moore–Colyer 2000). This optimum can be unbalanced by the inclusion of high levels of cereal–based concentrates in the diet. Therefore to maximise hindgut function it is important to maximise the use of high–energy fibrous feeds such as alfalfa and sugar beet pulp (USBP), while reducing the inclusion of concentrate feeds. This experiment sought to determine the effect of feed preparation, namely particle size on VFA profiles from a range of alfalfa : unmolassed sugar beet pulp diets.
Oocytes and assisted reproduction technology
Authors: Picton H.M. , Danfour M.A. , Coulthard H.
Published: June 2019

A number of methods can now be used to store the female germ plasm from farm species. New assisted reproductive techniques such as ultrasound guided oocyte pickup, followed by the in vitro maturation of oocytes together with cryopreservation enable the collection and storage of germinal vesicle or metaphase II secondary oocytes and more practically embryos after in vitro fertilisation. Following freezing using equilibration or vitrification protocols, oocytes and embryos can be stored at liquid nitrogen temperatures for as long as required. Despite much research interest, the efficiency of secondary oocyte freezing is low and the developmental potential of stored oocytes is directly affected by the local cellular and hormonal environment during maturation, fertilisation and extended culture in vitro. An alternative strategy which avoids many of the technical difficulties associated with mature oocyte freezing may be to cryopreserve primordial oocytes in situ within ovarian cortex. This approach has the added advantage that it may also provide a means of conserving the oocytes of rare species and it can be used to bank cells obtained from postmortem tissue samples or species for which IVF protocols may not have been fully optimised. Although the methodology is still in its infancy, when ovarian cryopreservation is combined with autografting, xenografting, or follicle culture, ovarian tissue freezing has the potential to restore or extend the fertility of domestic animals so maximising their genetic potential.
Strategies to maximise the allelic diversity maintained in small conserved populations
Authors: Fernández J. , Toro M.A. , Caballero A.
Published: June 2019

One of the main objectives in conservation programmes is to maintain the highest levels of genetic variability, for the population to be able to face future environmental changes and to assure long-term response to selection, either natural or artificial (Oldenbroek, 1999, Barker, 2001). The classical measure of genetic diversity is the expected heterozygosity, or gene diversity (GD), but allelic diversity (AD), or the number of different alleles per locus, also has evolutionary importance. Most optimal strategies for conservation have aimed to maximise GD (e.g. Caballero and Toro 2000), but AD has received much less attention. The objective of the present study is to test the efficiency of the maintenance of allelic diversity of strategies based either on the allelic diversity itself or on the expected heterozygosity in a small population, using information from molecular markers.