bluuebunny/crossref_metadata_2025 huggingface dataset:
Trapping of Dust Particles into Internal Resonances with the Inner Planets
Authors: Gomes Rodney S.
Published: June 2019

Trapping of dust particles into external resonances with the inner planets is a quite relevant phenomenon, which induces the formation of rings of dust around the planets' orbits, there being observational evidence of the Earth's resonant ring (Dermott et al., 1994). On the other hand, notwithstanding it is a less probable event, capture into internal resonance (diverging orbits) is predicted in numerical integrations of dust particles' orbits subject to Poynting-Robertson drag with one or two disturbing planets. Average theories, which give a good explanation for resonance trapping when the orbits are converging, do not allow capture for diverging orbits. Close approaches with the perturbing planet disallow the application of average theories, and numerical examples show that resonance trapping for internal resonances must have a chaotic origin. As expected from analytical theories, for the case of one disturbing planet, the particle's eccentricity decreases continually after capture and resonance is eventually broken. When two disturbing planets are present, however, there is not necessarily a decrease of the eccentricity, but it may increase, decrease or oscillate, although escape from resonance always occurs anyway.
The Evolution of Meteoroid Streams
Authors: Williams I.P.
Published: June 2019

The existence of meteoroid streams is indicated by the regular appearance of coherent meteor activity at specified times during the year. Since it is the interaction of the meteoroid with the atmosphere that is detected, the meteoroid has to be greater than about 100 micrometers in radius. Observation of these interactions gives information on individual meteoroids as well as collective phenomena. It is generally agreed that streams form through the ejection of dust particles from the surfaces of comets and asteroids at speeds considerably lower than the orbital speed. The subsequent motion of these particles is affected by gravitational perturbations from the planets and the effects of solar radiation forces. This review is intended to present an overview of the development of the subject and of our current state of knowledge.
The Formation and Evolution of the Perseid Meteoroid Stream
Authors: Harris Nathan W.
Published: June 2019

The orbital evolution of two modelled ‘Perseid’ meteoroid streams is investigated using direct numerical integration techniques. We conclude that, in the absence of significant meteoroid velocity determination errors, the observed meteoroid orbital semi-major axis distribution is a direct consequence of the cometary ejection process and not due to subsequent orbital evolution. A high ejection-velocity (~ 0.6 km s-1) model stream succeeds in reproducing the observations. Conclusions are made concerning how the orbital stability of Earth-orbit-intersecting Perseid metecroids varies with initial orbital semi-major axis.
Dynamic and Probabilistic Relation between Meteoroids and their Parent Bodies
Authors: Adolfsson Lars G. , Gustafson Bo Å. S.
Published: June 2019

We estimate the probability that specific meteoroids were produced by a specific parent body and obtain the ejection velocity and several other conditions of the ejection as a by-product. The duration of cometary activity leading to a meteor stream, or the epoch of a collision can be estimated from the ejection times of meteoroids in the same stream. The level of activity of a comet or probability of asteroid collisions can be estimated from the part of the orbit where ejection took place. We show that Phaethon ejected Geminid meteoroids over at least 3000 years lasting to as recently as ≈ AD 1600. Ejections are predominantly in the direction of the sun, i.e., from Phaethon's day side, and give insights into the ejection process which is suggestive of cometary activity. Our calculations account for the uncertainty in the observational data and include the effects of planetary perturbations, radiation pressure, Poynting-Robertson light drag and solar wind corpuscular drag.
Modelling the Ejection of Meteoroids from Comets
Authors: Jones J. , Brown P.
Published: June 2019

We have reworked Whipple's (1951) theory of the ejection of meteoroids from comets to include the effects of cooling by the sublimation of the cometary ice and the adiabatic expansion of the escaping gases. We consider only those particles moving significantly slower than the gas speed and find that the inclusion of these effects does not yield results much different from Whipple's theory. We have extended the theory to include the case of an active area in the form of a spherical cap and have shown how the characteristics of the ejection process change when the cap is in the form of a pit or a depression. We present a empirical formulae which should be useful to modellers of meteor stream evolution.
Recent near Earth satellite flux data: contributions in the definition of the interplanetary flux at 1 AU heliocentric distance
Authors: McDonnell J. A. M. , Gardner D. J. , McBride N.
Published: June 2019

Recently analysed hypervelocity impact data from retrieved satellites are summarised. Analyses of perforation data show that mean densities are low (around 1.5-2 g/cm3), impact velocities are consistent with radar meteor observations and that high aspect ratio particles are not found. Mean data, for Fmax > 30 μm agrees well with the Grün et al. Interplanetary flux model, though there is evidence of a strong bias towards the Earth apex of motion direction. For Fmax < 30 μm the data at LDEF's altitude is dominated by space debris.
Microparticle Impacts Observed on the Hubble Space Telescope Solar Array
Authors: Berthoud Lucinda , Paul Klaus
Published: June 2019

The recent recovery of the Hubble Space Telescope (HST) Solar-Array-1 offers a unique opportunity to improve our knowledge of the low Earth orbit (LEO) particle environment. The data from HST surfaces is particularly interesting for the meteoroid and debris community, as the Telescope was in orbit at an altitude of approximately 614 km and there has been no data from such a high orbit before.
Mars Dust Counter on Board ISAS PLANET-B
Authors: Igenbergs Eduard , Sasaki Sho , Färber Georg , Fischer Franz , Münzenmayer Ralf , Fujiwara Akira , Iglseder Heinrich , Glasmachers Albrecht , Grün Eberhard , Mukai Tadashi , Nogami Ken-ichi , Ohashi Hideo , Schwehm Gerhard , Svedhem Håkan , Yamakoshi Kazuo
Published: June 2019

PLANET-B is an ISAS spacecraft which will investigate the upper atmosphere and the surroundings of Mars between 1999 and 2001 To clarify the presence and characteristics of the Martian dust ring/torus, an impact ionization dust detector will be on board PLANET-B The detector (PLANET B Mars Dust Counter), which is an improved version of the Munich Dust Counters of HITEN and BREMSAT, will weigh only 630g with an aperture area 140cm2. The detectable mass range will be between 10-16g and more than 10-6g and the velocity range will be from 1km/s to more than 70km/s. Since PLANET-B executes retrograde elliptic orbits close to the zodiacal plane, our detector can investigate the spatial distribution of prograde dust particles from Phobos and Deimos with relative encounter velocity as large as or higher than 1km/s. PLANET-B MDC shall also measure the dust environment around the Earth and interplanetary and possibly interstellar dust particles.
Dust Near the Sun
Authors: Mann I.
Published: June 2019

Yielding the inner continuation of the interplanetary dust cloud, the dust at about 0.3 AU and closer to the Sun is studied under observing conditions different from those of the Zodiacal light. The F-coronal brightness indicates its optical particle properties as well as its overall spatial distribution. The present knowledge is based on visible and near infrared F-coronal observations and may be improved from data of the SOHO satellite in the near future. Some dynamical effects become particulary important for sub-μm particles in the solar vicinity. However, these particles seem to have only a small effect on the observable corona brightness, but are more accessible to in-situ experiments.
Dust Particles Near The Sun
Authors: Shestakova L. I. , Tambovtseva L. V.
Published: June 2019

The orbital motion of interplanetary dust grains in the sublimation zone near the Sun has been considered for graphite and silicate. Calculations showed that dust grains with initial radii s = 0.5 - 5 μm can form regions of enhanced concentration. The inner corona is slightly enriched with particles s = 0.3 - 0.6 μm due to the departure of the evaporated grains onto highly elliptic orbits. However, they may be not recognized due to their small contribution to the total brightness along the line-of-sight compared with the background of the more typical Zodiacal particles. The astrosilicate dust grains do not form zones of enhanced concentration. Finally, particles with initial radii from 0.3 to 4 μm leave the Solar system and become β-meteoroids.
Composition and Optical Properties of Cometary Dust
Authors: Hanner Martha S.
Published: June 2019

Comet dust consists primarily of silicate and carbonaceous material. The carbonaceous material is not yet well-characterized. The 3.36 μm emission feature arises primarily from gas phase molecules, while a small feature at 3.29 μm may be due to aromatic hydrocarbons in the grains. Olivine, a high temperature condensate, is present in some comets. Polarization and albedo maps have shown that the coma is not uniform; an inner halo of large particles may be present.
Meteorites from Comets? Recent Observational Developments
Authors: Campins Humberto
Published: June 2019

Although most meteorites come from asteroids, some could originate from short-period comets. The identification of comet-asteroid transition object 4015 Wilson-Harrington as the first Apollo object known to have a cometary origin, confirms that short-period comets leave behind nonvolatile residues, from which meteoroids with low Earth-encounter velocities can originate. Studies of cometary fireballs suggest that some cometary meteoroids have high enough strengths to have survived atmospheric entry as cometary meteorites, which have either not been found or recognized. The presence of unequilibrated anhydrous silicates in cometary dust represents a significant difference between cometary material and CI and CM meteorites.
Laboratory Measurements of Light Scattering by Dust Particles
Authors: Combet Patrick P. , Lamy Philippe L.
Published: June 2019

We have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.
Coherent Backscatter Opposition Effect from Saturn Ring Particles and Their Regoliths
Authors: Horn L. J. , Nelson R. M. , Smythe W. D. , Hapke B. W.
Published: June 2019

The photometric phase curves of Saturn's A and B rings exhibit a sharp peak in reflectance when the phase angle approaches zero, commonly known as the opposition effect. Recent work has suggested that the width and amplitude of the opposition effect may be consistent with coherent backscattering from wavelength-sized grains which cover the surfaces of macroscopic ring particles.
Improvement of ion acceleration in radiation pressure acceleration regime by using an external strong magnetic field
Authors: Cheng H. , Cao L. H. , Gong J. X. , Xie R. , Zheng C. Y. , Liu Z. J.
Published: June 2019

Two-dimensional particle-in-cell (PIC) simulations have been used to investigate the interaction between a laser pulse and a foil exposed to an external strong longitudinal magnetic field. Compared with that in the absence of the external magnetic field, the divergence of proton with the magnetic field in radiation pressure acceleration (RPA) regimes has improved remarkably due to the restriction of the electron transverse expansion. During the RPA process, the foil develops into a typical bubble-like shape resulting from the combined action of transversal ponderomotive force and instabilities. However, the foil prefers to be in a cone-like shape by using the magnetic field. The dependence of proton divergence on the strength of magnetic field has been studied, and an optimal magnetic field of nearly 60 kT is achieved in these simulations.
Oscillation Reduction and Frequency Analysis of Under-Constrained Cable-Driven Parallel Robot with Three Cables
Authors: Hwang Sung Wook , Bak Jeong-Hyeon , Yoon Jonghyun , Park Jong Hyeon
Published: June 2019

Cable-driven parallel robots (CDPRs) possess a lot of advantages over conventional parallel manipulators and link-based robot manipulators in terms of acceleration due to their low inertia. This paper deals with under-constrained CDPRs, which manipulate the end-effector to carrying the payload by using a number of cables less than six, often used preferably owing to their simple structures. Since a smaller number of cables than six are used, the end-effector of CDPR has uncontrollable degrees of freedom and that causes swaying motion and oscillations. In this paper, a scheme to curb on the unwanted oscillation of the end-effector of the CDPR with three cables is proposed based on multimode input shaping. The precise dynamic model of the under-constrained CDPR is obtained to find natural frequencies, which depends on the position of the end-effector. The advantage of the proposed method is that it is practicable to generate the trajectories for vibration suppression based on multi-mode input-shaping scheme in spite of the complexity in the dynamics and the difficulty in computing the natural frequencies of the CDPR, which are required in any input-shaping scheme. To prove the effectiveness of the proposed method, computer simulations and experiments were carried out by using 3-D motion for CDPR with three cables.
Breeding programs in dairy cattle - current and future considerations
Authors: Freeman A. E.
Published: June 2019

Methods of evaluating dairy cattle using mixed models with Best Linear Unbiased Prediction properties have progressed from the sire model to the animal model. Definitions of effects in models need refinement, particularly for contemporary groups. Pedigree selection and progeny testing is the standard for producing sires used in artificial insemination, but multiple ovulation and embryo transfer schemes are being tried. Efficient production is necessary under conditions of surplus. Efficiency can be achieved by higher production per cow and reducing costs by improved reproduction, increased herd life, reduced health costs, and reduced dystocia. Preferential treatment is a major problem. New biotechnological developments such as bovine somatotropin, mitochondrial genetics, sexing semen, embryo transfers, cloning, transgenic animals, and markers are considered as potential new technologies that may be useful for dairy cattle improvement.
Milk compositional quality and the rôle of forages
Authors: Thomas C.
Published: June 2019

In most experiments in which the influence of forage to concentrate ratios on milk quality have been examined, the composition of the forage has been incidental to the purpose of the trial. Legumes have resulted in higher yields of milk than grasses of similar digestibility. However, these increases were a reflexion of higher outputs of protein and lactose, since the feeding of legumes resulted in lower contents of milk fat. Changes in the digestibility of forage have shown considerable variability in response, in terms of the concentration of milk solids. However, an increase in digestibility of forage has not resulted in decreases in the yield of fat and, further, the yield of protein has been increased.

There is no indication that there is a requirement for ‘long hay’ to maintain milk quality and that a reduction in the chop length of silage has any influence on milk composition. However, the fine grinding of grass, which was the sole forage component of the diet, has caused a marked decrease in milk fat content. This effect was not apparent when finely ground and pelleted dried grass was used as a supplement but only in ad libitum feeding regimes.

Attempts to increase the content of milk fat in May and June by the supplementation of grazed grass with small quantities of hay have had little influence on milk yield and fat content. A much greater effect was observed when grazing was restricted and silage offered ad libitum overnight. The increase in fat content may be overcome by a reduction in milk and protein yield.

In general, the changes in milk composition have been small and this is likely to be a result of the high proportion of forage in the diets examined. The quantification of response in yield and content of fat and protein to changes in forage composition requires a change in approach. More emphasis should be given to the examination of the interaction between level or type of concentrate and the composition of the forage. Further, these trials should be accompanied by experiments to examine the effects of the dietary changes on the end products of digestion.
Herd management effects on compositional quality
Authors: Dodd F. H.
Published: June 2019

Lactation depends on milk secretion and the storage of the accumulating milk, followed by milk ejection and effective milk removal during milking. Environmental and disease factors may affect each of these stages independently and, thus, alter the milk composition. With normal milking intervals, the secretion of each of the milk constituents is continuous and linear with time. Subsequently, changes in milk composition occur during storage in the udder, mainly through the free movement of water between milk and blood and as a consequence of maintaining their osmotic equilibrium. The changes in composition are greatest in infected glands. The composition of milk varies in different parts of the udder: the fat content is much lower in the milk in the udder and teat sinuses. Following milk ejection, 10 to 20% of the milk is retained and cannot be removed by milking; the fat content of this residual milk will usually exceed 150 g/kg. The dynamics of these changes are complex and, whilst they may bring about large alterations in the composition of the milk obtained at individual milkings, their effect over longer periods is small. Thus, although incomplete milking, changing the milking intervals and increasing the frequency of milking will cause large fluctuations in the composition of milk at individual milkings, their longer-term effects are minor. The main effect of high levels of udder disease will be to reduce the lactose content but the serum protein level will increase and changes will occur in the concentrations of potassium, sodium and chloride ions. The design of milking equipment and the hygiene during farm storage of milk may materially alter the quality of milk for processing, because of lipolysis.
2.6 Packages for Intensive Farm Enterprises
Authors: Filmer D. G.
Published: June 2019

The number of computer “packages” now being offered to farmers is growing rapidly and this paper does not present an exhaustive or critical account of these. Rather, it concentrates on packages offered by the feed trade to the intensive animal production sector of British agriculture. The paper will deal with the cattle, pig and poultry sectors, in that order, and then examine computer applications as they have developed, are now, and how they may become. Finally, the important criteria when considering the potential success of new computer packages will be described.

Though some may consider the cattle sector to be less progressive than the pig and poultry sectors, as far as the application of the computer is concerned, cattle led the way. The earliest application was in the late 50's and early 60's, when the feed trade abandoned hand formulation of cattle feeds and provided one of the first commercial applications of linear programming—least-cost feed formulation. Though in those days, diet specifications were heavily constrained by raw material limits (for example, 5% fixed linseed cake and 5% copra cake in a well known high performance dairy feed), the effects were to reduce formulation costs by about 5% (£1 per ton in those days!). Cattle feeds were soon universally computer formulated, closely followed by pig feeds. Broiler and turkey foods remained as fixed formulae for some time but, as nutritional knowledge increased, these too fell into line. Currently, only a few specialized diets, such as baby pig foods, remain as fixed formulae. The remaining products now have very few raw material constraints left but many are tightly constrained on amino acids, undegradable protein, fatty acid levels and rations, various descriptions of energy components, etc.
2.7 Hill Resource Management
Authors: Eadie J. , Maxwell T. J.
Published: June 2019

For the purpose of this paper ‘hill resources’ will be interpreted to mean the land resources of the hills and uplands. ‘Management’ will be assumed to include strategic and tactical decision making. It will further be assumed that the invitation is to discuss computers in animal production in relation to farming practice and not to research aimed at improving farming practice. In fact, computers will hardly be discussed at all. Computers are tools in this context and are aids to decision making. It seems much more likely that they will be more effectively used if we can be clear about decision making and its nature in relation to current knowledge and understanding and to the needs of farming systems based on the land resources of the hills and uplands.

The official statistical deposition of hill sheep farms in Scotland includes reference to land resources; these farms have more than 90% of the land in rough grazings and less than 15% in crop. The definition includes reference to the allocation of man-days among sheep and cattle. The Scottish upland farm description also includes reference to land resources and there are, for example, constraints in the relationship of crop and rough grazing areas. Hill and upland farms in England and Wales come into the category known as Livestock Rearing farms, where distinction between hill sheep and upland farms is made on the distribution of man-days among cattle and sheep.
Use of vegetable and arable by-products
Authors: Francis G. H.
Published: June 2019

In Agricultral Statistics, United Kingdom, 1974, the area of land devoted to vegetables grown in the open for human consumption is given as 187 500 ha. This amounted to some 4% of the tillage land in the UK, and along with similar areas of sugar beet and maincrop potatoes would appear to offer significant scope for the utilization of associated by-products as feed for livestock. The range of such crops produced in the UK is quite wide, but climatic and market pressures will influence actual cropping from year to year. Relevant details for the United Kingdom are set out in Table 1, and it will be seen that in 1974 England and Wales accounted for 95, 78 and 100%, respectively, of the areas of outdoor vegetables, maincrop potatoes and sugar beet grown in the UK. In the following, therefore, the discussion will be concentrated on the problems of production and distribution of vegetable and arable by-products. Similar problems of distribution will no doubt occur in other countries as well.
Effect of environmental temperature on brown adipose tissue development in the neonatal lamb
Authors: Darby C. J. , van de Waal S. , Lomax M. A. , Symonds M. E.
Published: June 2019

A major financial and welfare problem is the loss of 1 to 4 million lambs annually in the United Kingdom (Slee, 1979) with many of these deaths being caused by failure of the lamb to maintain normal thermoregulatory responses in the cold. This may be associated with a change in the response to cold exposure from non-shivering thermogenesis (NST) to shivering thermogenesis (ST) as brown adipose tissue (BAT) is replaced by white adipose tissue over the first 2 weeks of life in the lamb (Symonds, Andrews and Johnson, 1989).

It has been shown that environmental temperature can affect BAT development in the lamb (Gemmel, Bell and Alexander, 1972) and calf (Casteilla, Champigny, Bouilland, Robelin and Riquier, 1989) but it is not known what effect this has on the thermogenic capacity of BAT or how it may alter the ability of the lamb to thermoregulate.

This study investigated the effect of artificially rearing lambs at warm or cold ambient temperatures on the thermogenic capacity of BAT and the extent to which metabolic rate and the ability to respond to warm and cold challenges was altered by these treatments over the first 9 days of life.
6.15 The Effects of Soil Cobalt on Rumen Vitamin B12 Synthesis
Authors: McDonald P. , Suttle N. F.
Published: June 2019

The high level of cobalt (Co) in soil relative to herbage means that soil accidentally ingested with herbage may constitute the larger source of the element for vitamin B12 synthesis by rumen microbes.

A continuous culture simulation of rumen fermentation (Rusitec: Czerkawski and Breckenridge. 1977) was used to determine the extent to which soil Co was used for microbial vitamin B12 synthesis. A low Co hay (0.044 mg/kg DM), 7.25 g DM/day, was “fed” to each of four vessels for a period of 8 days to provide resting values for vitamin production. A chalk, a sand, a clay or a loam, with Co concentrations ranging from 0.70 to 64.5 mg/kg DM (see Table 6.15.1), were then added at 0.70 g/day, to the hay in separate vessels each morning for 14 days. For a further period of 10 days, the hay in two vessels was supplemented with either chalk or loam at 1.4 g/day. Daily vitamin B12 production was measured by analysis of each vessel's effluent for cobalamin (cbl.), using a modification of the method of Green (1980). Vitamin B12 analogue production was assessed from the Lactobacillus leichmannii microbial assay of the effluent. All vessels produced a “roughage” fermentation (acetate c. 50% and propionate c. 20% of the total volatile fatty acids) with the soil supplements.
7.1 Protein Digestion in Grazing Sheep
Authors: Corbett J. L. , Furnival E. P. , Inskip M. W. , Pickering F. S.
Published: June 2019

In 23 experiments, measurements were made over 4 or 5 day periods of the digestion of herbage by lambs (Expts 1-10 and 14-18, Table 7.1.1) and adult sheep (Expts 11-13 and 19-23) grazing phalaris (P. aquatica), lucerne and unfertilized native pastures. All 38 animals used (Corriedales) had rumen and simple abomasal cannulae; seven adult sheep also had a simple ileal cannula. Corbett, Furnival, Inskip, Perez and Pickering (1976) and Corbett (1981) have described the techniques used for estimating intakes of organic and digestible organic matter and nitrogen (OMI, DOMI, NI) and the fractional outflow rates (FOR/h) of liquid from the rumen, the rate and composition of digesta flows and microbial protein production by reference to intra-ruminally infused 103Ru-phenanthroline, 51CrEDTA and Na235S04.
8.4 The Effect of the Quantity and Composition of Ruminally Degraded Nitrogen on Microbial Nitrogen Synthesis and Diet Formulation
Authors: Beever D. E. , Cottrill B. R. , Osbourn D. F.
Published: June 2019

Recent proposals (ARC, 1980) have clearly identified the need to supply adequate ruminally degradarle nitrogen (RDN) if rumen microbial protein yields are to be optimized and they provide a basis on which the required quantities of RDN can be calculated. However, apart from the suggestion that urea is used with only 80% of the efficiency of degraded protein N as a source of RDN in the synthesis of microbial protein, the present scheme fails to qualify the RDN composition (i.e. protein N (PN) vs. NPN) most likely to promote optimal microbial synthesis.

Cottrill, Beever and Osbourn (1982) examined the isonitrogenous supplementation of maize silage fed to growing calves with four different NPN:PN ratios in the supplement and showed a 29% increase in total duodenal amino acid (DAA) flow at the first increment of PN (fish meal). Of this increase, almost 87% could be accounted for by an increased duodenal microbial protein (DMP) flow. Higher levels of PN inclusion did not promote any further increases in DAA, despite increases in undegraded dietary protein (UDP) flow, due to a significant reduction in DMP flow. From these data, a further examination of total RDN supply and its composition in relation to MP synthesis was undertaken and the results are presented in this paper.
Use of pepsin-pancreatin system to estimate intestinal digestibility of protein in ruminant foods and undegraded residues
Authors: Antoniewicz A. M. , Kosmala I. , Hvelplund T. , van Vuuren A.
Published: June 2019

Intestinal digestibility of food protein is one of the important factors of most protein evaluation systems. Therefore it was determined in the experiments with duodenal infusions of foods (Hvelplund, 1985) or using mobile bags (Sauer et al., 1983; Hvelplund, 1985; de Boer et al., 1987; Antoniewicz et al., 1992). To avoid the use of cannulated animals, in vitro enzymatic methods have been developed (Antoniewicz et al., 1992). Incubation of food with pepsin and pancreatin correlates with the digestibility of food protein (Akeson and Stahmann, 1964) and is suitable (r = 0·95 to 0·99) to determine protein digestibility in pig foods (Babinszky et al., 1990). The aim of the study was to develop the best conditions of pepsin-pancreatin digestion and to evaluate the predictive ability of the method to determine protein disappearance measured using mobile bag technique.
In vitro techniques to replace in vivo methods for estimating amino acid supply
Authors: Hvelplund T. , Weisbjerg M. R.
Published: June 2019

Expressing the protein value of a food involves measurements of several of its characteristics. Many in vivo studies have shown, that the protein degradability in the rumen varies substantially both between and within foods and therefore estimation of protein degradability in the rumen is an important task in protein evaluation. The most common method used has been the in situ (in sacco, nylon bag) method but many in vitro methods have been introduced and are based on use of either buffer solubility, chemical methods, rumen fluid or enzymes. None of these in vitro methods has proven to be of general use. In further development of in vitro methods as well as the in situ method a major problem is lack of a set of samples with a ‘true’ in vivo degradability which can be used for calibration of alternative methods. Microbial protein synthesis in the rumen has to be related to food characteristics which can be analysed easily. In vitro methods which can predict organic matter digestibility in foods are available and can be used to predict microbial protein synthesis in the rumen. Intestinal digestibility of undegraded dietary protein varies substantially both between and within foods and easy methods to estimate intestinal digestibility are therefore essential. The mobile bag method is easy to use and seems to give reliable results on most foods but requires access to duodenal cannulated animals which prevents this method from being routine. Alternative in vitro methods have been developed but further research is required for validation of these methods on a wide range of foods before they can be accepted for general use.
In vitro techniques for modelling rumen transformation and syntheses
Authors: Sauvant D. , Broudiscou L. , Giger-Reverdin S.
Published: June 2019

There are two major ways to model the microbial activity in the rumen. The first is the material or physical modelling with in vitro systems and the other is mathematical modelling with sets of equations.

The evaluation of the ability of in vitro devices is to mimic in vivo ruminal digestion needs to perform first a typology of the most known and published in vitro procedures. This typology is aimed at clustering them according to their basic function (batch or continuous), to their major targets (studies of food degradation, of microbial proteosynthesis, of volatile fatty acid (VFA) production and profile, of gas production and composition, of outflow influences, of interactions between microbe species … also of prediction of intake of food nutritive value), to their level of time integration (cumulative at a given time or kinetic values), to their actual validity to simulate one or several items of ruminal digestion. Another key of typology of in vitro procedures is also the nature of the active substance, microbes or enzymes.

Rumen mathematical modelling can be variously used in connection with in vitro and in vivo experimentations. At least three main targets can be pursued in this perspective:

To model in vivo ruminal digestion. This aspect already has a long history because the first actual mechanistic model of whole rumen digestion was that of Baldwin et al. (1970). Since this date around a tenth of whole rumen models were proposed. Their current limits are those of the knowledge on rumen digestion: proteosynthesis, VFA production, nutrient absorption, liquid and particle outflows. As far as we are aware, none of these published rumen models was checked against in vitro data. One reason could be that some of them were more or less built from in vitro data.

To model in vitro devices. Surprisingly no such specific model seemed to be published until now. In our opinion it is urgent to develop such models because they could be highly useful: to compare analogies and discrepancies between the various in vitro procedures; to try to build a unique model of in vitro ruminal digestion which could be parameterized according to the type of device; to elucidate intrinsic properties of micro-organisms.

To model both in vitro and in vivo digestion. This way is likely to be the most difficult but it is also potentially the most fruitful. Effectively the use of an intermediate mathematical model of the rumen seems to be a priori the best way to check the major areas of analogy and discrepancy between in vivo and in vitro events. Thus this approach could be an objective mean of validation of in vitro studies.
Funding and facilitation – Defra's pig science and technology transfer programme
Authors: Garwes D , Backwell C , Mills R , Fox A , Stuart J , Davies Z
Published: June 2019

The Department for Environment, Food and Rural Affairs (Defra) is committed to promoting a sustainable, competitive and safe food supply chain that meets consumers’ requirements. Scientific research is commissioned to generate evidence on which policies and strategies are based, and to provide UK producers with management options that bring their livestock enterprises more in line with the needs of the consumer and regulatory requirements. The principle research programmes within the pig science portfolios have a total value of around £9.2 million. They cover the pig production sciences of nutrition, genetics, reproduction, meat quality and management systems, pig health and welfare, and ways to assess and ameliorate the environmental impact of pig farming. To facilitate uptake of the information generated by the research programmes, a range of knowledge transfer programmes are in place, including fact sheets produced for the Knowledge Transfer for Livestock initiative and the recently established Learning Skills and Knowledge programme. The aim of the Defra Science programme is to ensure soundly based policy, to prepare UK producers for longer–term changes, to make better use of risk management, and to provide the pig industry with tools to achieve improved economic and environmental sustainability.
Regaining high health status of UK pig herds: Can it be done? How can it be done?
Authors: Chennells D.J.
Published: June 2019

Until the 1990s, defining and maintaining a High Health (HH) Status was relatively straightforward. Organisations such as the Pig Health Control Association were able to define and identify certain diseases such as Enzootic Pneumonia (EP), (Mycoplasma hyopneumoniae) or Swine Dysentery (SD) (Brachyspira hyodysenteriae,) and then establish, by hysterectomy or medicated early weaning (MEW), “clean” units which became the Nucleus units of the breeding companies. These produced “clean” pigs to populate Multiplication units that eventually passed on HH breeding stock to commercial customers. Relatively straightforward laboratory and abattoir monitoring could give reasonable, repeatable assurance to customers. Good biosecurity maintained this HH status and many HH commercial units were established by destocking, cleaning, and restocking with HH pigs from these breeding companies. Then the wheels started to fall off!
The American dream: A quest for high health
Authors: Loula T. J.
Published: June 2019

There has been at least a decade-long march to improve the health of the US swine industry. This coincided with rapid expansion of many farms and a tremendous change in the ownership structure of the US swine industry (fewer owners having larger sow farms and owning or controlling more pigs). Prior to 1990, the industry consisted of more typical farrow-to-finish farms that would live with chronic diseases such as atrophic rhinitis, Actinobacillus Pleuropneumonia (APP), Swine Dysentery, Mycoplasma pneumonia and a host of enteric organisms. Many of these would persist on an individual farm until either the owner became frustrated, or profitability and production were so poor that depopulation/repopulations were done. This was basically the technology of the 1980s. The late 1980s and early 1990s brought a tremendous amount of new sow farm construction or farm conversion. Nearly all of these were either farrow-to-wean or occasionally farrow-to-feeder pig (25 kg) with off-site finishing. The off-site nurseries and finishers (or recently wean-to-finishers) were built in several different configurations. Some would have 1 week’s worth of pigs on a site, some would have multiple weeks of nursery, some would have multiple weeks of finishing, or some would comingle farms and have only 1 week of nursery or 1 week of finishing on a site.
Emerging feed legislation and related issues
Authors: Millar Keith
Published: June 2019

According to David Byrne, EU Commissioner for Health and Consumer Protection (DG SANCO), ‘Strengthening rules on the safety of animal feed is one of the cornerstones of the EU's food safety strategy’. The main EC developments affecting animal feed can be summarised under the following headings:

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General Food Law Regulation

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Proposal for Feed Additives Regulation

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Proposal for Feed Hygiene Regulation

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Positive List of Feed Materials

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Official Food and Feed Controls

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GM Food and Feed
Autofom – a new and improved technology for the UK pig industry?
Authors: Haighton M.W.
Published: June 2019

No matter how specific an abattoir's requirement, and no matter how many different incentives are offered to pig producers to encourage them to send in a particular sort of carcase, the bottom line is that pigs do not come like nuts and bolts.

Variable factors such as genetic make–up, nutrition, production system, feeding regime, environment and disease status all combine to result in decreasing the uniformity of the carcases found inside the chillers of UK abattoirs. This variation not only occurs in carcases from different units but also between carcases produced on the same unit, and it’s not uncommon to find a wide spread of carcase weights, lengths and fat deposition within one batch of pigs.

This lack of uniformity provides a headache for all pig processors for the sole reason that, over the years, their customers have become a lot more specific with their meat requirement. For example, several years ago a third party processor would buy 500 loins of pork at a premium price for pork chop production.
Longitudinal study of adverse behaviour of undocked pigs in two different housing systems
Authors: Van de Weerd H. A. , Docking C. M. , Day J .E. L. , Breuer K. , Edwards S. A.
Published: June 2019

The development of adverse behaviour in group–housed growing/ finishing pigs with intact tails was studied in a straw–flow housing system and in a part–slatted system with a commercial enrichment object. Food intake, body weight and behaviour were monitored over the finishing period, with tail biting outbreaks defined as an occasion where three or more pigs within a group had freshly damaged tails and tail biting behaviour was ongoing. Data from the two systems were analysed to identify tail–biting outbreaks and behavioural changes over time. Levels of pig manipulation were higher in the part–slatted system. Over time, pigs in both systems showed reduced interest in the enrichment provided, but not in each other. Despite the presence of the enrichment device, tail biting occurred in all groups in the part–slatted system, but only 1/12 groups in the straw–flow system. The amount of time occupied by manipulation of the enrichment provided was very significantly higher for straw than for the commercial object. Better design of enrichment strategies is therefore needed and should be based on species–relevant requirements.
The effect of feeding a high fibre diet from mid lactation until breeding on subsequent litter size of sows
Authors: Ferguson E.M. , Ashworth C.J. , Hunter M.G. , Penny P. , Slevin J. , Edwards S.A.
Published: June 2019

The feeding of high fibre diets to sows prior to ovulation has been shown to have beneficial effects on embryo viability, leading to a possible increase in piglet litter size. This trial was conducted to look at the effect of feeding sows a high fibre diet from mid lactation until breeding on subsequent litter size on a commercially run farm. The sows used were either Large White or Large White x Landrace in genotype and ranged from parity 1 to 7. The sows were allocated to receive either a cereal-based control diet (C), or a high fibre diet (HF) of similar specification but containing unmolassed sugar beet pulp (USBP) at a 20% inclusion rate during lactation and 40% from weaning to oestrus. The diets were fed from day 11 of lactation until oestrus. The sows were inseminated at oestrus and then fed a standard gestation diet until farrowing. The trial was conducted over a 3-month period and in total 198 sows received the HF diet with the rest of the sows over the 3-month period acting as controls (496) on the cereal-based diet. The effect of the diet on total litter size and the number of piglets born alive per sow was analysed in a general linear model (Minitab release 12.1). The combined results for both breed types showed that sows fed the HF diet had a significantly higher number of piglets born (12.37 ± 0.27 versus 11.41 ± 0.26, P<0.01) and a higher number of piglets born alive (11.47 ± 0.26 versus 10.85± 0.26, P<0.01) compared to 130 control fed sows matched for farrowing week. The difference in piglet litter size was still apparent when all the control sows farrowing over the 3 month trial period were included in the statistical analysis, with values of 12.47 ± 0.27 versus 11.79 ± 0.15 (P<0.05) for total number of piglets born and 11.77 ± 0.26 versus 11.16 ± 0.14 (P<0.05) for the number of piglets born alive for the HF and control diet respectively. Based on the results from this trial and previous studies, feeding a diet with a high content of USBP during late lactation and prior to insemination can increase the total number of piglets in the litter and the number of piglets born alive. This effect is less marked in crossbred sows with high baseline performance.
Effect of neutraceutical supplementation on the growth performance and antioxidant activity in liver and plasma of weaned piglets
Authors: Guy J.H. , Arkle S. , Mantle D. , Seal C.J. , Blanchard P.J. , Toplis P.
Published: June 2019

Post–Weaning Multisystemic Wasting Syndrome (PMWS) can result in mortality levels of up to 80% in weaned piglets, and Porcine Circovirus type 2 (PCV2) has been identified as one of the primary causative agents. Neutraceutical products, based on plant and herbal extracts and containing high levels of natural antioxidants may be beneficial in reducing stress on the piglets’ immune system by elevating blood antioxidant levels, and assisting with the piglets defence against PMWS. The aim of this experiment was to assess the effect of supplementation with neutraceutical products on the growth performance and antioxidant activity in liver and plasma of piglets. It was undertaken on a farm positive for PCV2, but where pigs were not showing clinical signs of PMWS. Groups of newly weaned pigs were offered one of three diets ad libitum for a period of 26 days, standard creep and starter/link control rations, or one of two experimental rations (including Neutraceutical–mix, N, or Lycopene, L), chosen for their potential to boost antioxidant activity. Growth performance and feed intake were monitored, and samples of blood and liver collected at slaughter (54 days of age) and analysed for antioxidant activity. Although L pigs ate significantly less feed during the creep period (P<0.05), there were relatively few performance differences between treatments. However total antioxidant activity in liver samples was significantly higher for the N treatment (P<0.001) and activity of plasma superoxide dismutase was significantly higher in the L group. In conclusion, growth performance of weaned piglets following the addition of Neutraceutical supplements was similar to control groups, and there were significant increases in antioxidant activity of these animals. On the basis that increased levels of circulating blood antioxidants reduce stress on the piglets’ immune system, the results of the current study suggest that these supplements may be of benefit to piglets under immune stress, such as in clinical cases of PMWS.
Partitioning degradation of feeds between different segments of the equine digestive tract
Authors: Hyslop J. J.
Published: June 2019

This paper describes how experimental adaptation of the mobile bag and in situ porous bag techniques for use in nutrition studies with equines, combined with mathematical modelling of feed degradation profiles and digesta passage rates, allows the quantitative partition of feed degradation amongst the major segments of the equine digestive tract. Dry matter effective degradability values in the small intestine (pre–caecal), caecal and colonic segments of the equine digestive tract for four fibre feeds are presented. Measurement of digesta passage rates in the caecum and total tract of equines are also discussed. Further studies are now required to capitalise on this development and partition degradation of individual feed constituents in common equine feeds across each of the major segments of the equine digestive tract. This would allow optimum, balanced and healthy diets to be formulated in practice across a wide range of equine husbandry systems.
Preweaned Thoroughbred (Equus caballus) foals exhibit fewer behavioural signs of distress if accompanied by a handler while separated from their dam during covering
Authors: McGee S , Smith H V
Published: June 2019

Thoroughbred mares (Equus caballus) are usually first teased 6 days post foaling and during this brief (often 3-6 minutes) process the mare's foal will be left alone in its stable. This will be repeated daily until the mare goes out of season. During this part of her cycle she may later be sent for covering by the resident stallion. On some farms the foal is alone in its stable during covering and this period can last for anything from 20 minutes to an hour, during which the foal typically exhibits signs of considerable distress. Though the foal can be heard whinnying for the mare, it has not previously been noted what behaviours the distressed foal exhibits during this separation. Though a recent study by Houpt (2002) looked at responses of 10 pony mares and their foals to brief weekly periods of separation at up to nine weeks of age, most research on separation distress in foals has previously been done with respect to the artificial weaning process, an event that most Thoroughbred foals experience by 6-7 months of age.