bluuebunny/crossref_metadata_2025 huggingface dataset:
Welfare considerations in future selection and management strategies
Authors: Webster A. J. F.
Published: June 2019

This paper considers the welfare implications of breeding, feeding and managing dairy cows for increased productivity. The physiological demands of lactation for the high genetic merit dairy cow are exceptional, less in their intensity and more in their duration. Most welfare problems can be attributed less to productivity per se than to systems of feeding, milking and management that are unsuitable to the genotype of the high yielding cow. These include the inadequacies of wet grass silage as a staple food and the abnormal restriction of cows to twice-daily milking. It is also necessary to consider welfare problems that may arise from the application of new technologies to increase milk yield or to increase the rate of genetic progress. These may be related to the process itself or to its consequences. It is proposed that the commercial exploitation of these new technologies should be controlled by legislation similar to that for the protection of animals used for scientific purposes which applies a cost-benefit analysis to determine whether the cost to the animal can be justified in terms of any potential benefit to society.
Setting research agendas for Kenya
Authors: Ndiritu C. G.
Published: June 2019

As resources available for agricultural research and development become increasingly scarce, the Kenya Agricultural Research Institute (KARI) has taken steps to define a clear research agenda. This effort has taken the form of formal priority setting in various research programmes. Priority setting is a key step in the formulation of a research agenda because priority setting, almost by definition, increases the efficiency and relevance of our research programmes by adding valuable structure to our wide information base on agro-ecological and socio-economic conditions in the country, by focusing attention on client constraints and by specifying the potential impact of research on these constraints.

The process of establishing clear and systematic priorities in our research programmes allows us to take a proactive rôle in soliciting government and donor support for areas identified as vital to agricultural development efforts. Perhaps most important, the priority setting processes developed at KARI have helped to broaden participation in formulating our research agenda by including a wide range of stakeholders and clientsfrom outside the Institute and in the process widened and deepened our constituency base.

Within specific programmes, the priority setting process has comprised five interrelated and cumulative steps: (1) compiling the information base on relevant commodities and regions; (2) identifying programme research target zones and research themes; (3) eliciting the potential for technology generation and adoption; (4) estimating research-induced social benefits; and (5) establishing research priorities and medium-term resource allocation guidelines with programme stakeholders.

All but a handful of our commodity research programmes, which include a number of livestock research programmes, have completed this five-step procedure. A similar process has been developed for regional and factor-based research programmes, which should have clear research priorities and resource allocation guidelines in 1998. Once all programmes have completed their respective priority setting activities, we will embark on an Institute-wide priority setting exercise that will pit programme against programme with a view to establishing a coherent set of priorities for the entire organization.
Global food demand and the contribution of livestock as we enter the new millennium
Authors: Delgado C. L. , Courbois C. B. , Rosegrant M. W.
Published: June 2019

People in developed countries currently consume about three to four times as much meat and fish and five to six times as much milk products per capita as in developing Asia and Africa. Meat, milk and fish consumption per capita has barely grown in the developed countries as a whole over the past 20 years. Yet poor people everywhere clearly desire to eat more animal protein products as their incomes rise above the poverty level and as they become urbanized. Growth in per capita consumption and production has in fact occurred in regions such as developing Asia and most particularly China. Per capita consumption of animal proteins and use of cereals for animal food in Asia have both grown in the 3 to 5% per annum range over the past 20 years. By 2020, according to the International Food Policy Research Institute's IMPACT model projections, the share of developing countries in total world meat consumption will expand from 47% currently to 63%. Of the global total projected increase in meat consumption, 40% is from pork, 30% is from poultry and 24% is from beef. The latter helps mitigate the otherwise much larger decline in real beef prices expected through 2020. Projected annual growth in meat consumption in China of 3.2% per annum through 2020, up from 8.3% per annum from the early 1980s to the early 1990s, drives these results.

A rapidly expanding supply of feedgrains will be essential to achieving the desired production increases for livestock products without undue upwards pressure on grain prices, especially in view of the rôle of monogastrics and the relative increase in industrial production in developing countries. IMPACT projections under various technical and economic assumptions suggest that there is enough production supply response in world systems to accomplish these production increases smoothly. Sensitivity analysis of the impact of restrictions on China's ability to produce more feedgrains illustrates that in a system of linked global markets for cereals and livestock products, such restrictions are not effective at lowering Chinese livestock consumption, which is driven by global trade in manufactures, although they do lower Chinese livestock production. The resulting imbalance raises world food costs by one-third in 2020 over anticipated levels, encourages increased livestock exports from Latin America, discourages livestock exports from the USA and reduces meat and cereals imports and consumption in the poorer countries of Africa and Asia.
In vitrotechniques as tools to predict nutrient supply in ruminants
Authors: Tamminga S. , Williams B. A.
Published: June 2019

In vitro techniques are widely used to predict the nutritive value of foods for farm animals. However, food evaluation systems are moving towards systems based on nutrient flows rather than on energy or protein. Nutrients are supplied via the digestive tract and presently available in vitro methods are inadequate to simulate the complicated and non-steady-state processes in this tract. This is partly due the lack of adequate in vivo reference values and partly due to a too-high degree of standardization and simplification. Future developments should therefore aim to develop in vitro systems which closely monitor the dynamics of the digestive processes. Adequate interpretation of the results may require sophisticated mathematical models.
A history ofin vitrotechniques
Authors: Minson D. J.
Published: June 2019

Regressions relating in vivo digestibility to chemical composition of the food have residual standard deviations that are unacceptably high. The development of the two-stage in vitro technique inoculated with rumen liquor (Tilley and Terry, 1963) allowed dry-matter digestibility to be predicted with greater accuracy. This success was followed by a series of developments which replaced rumen liquor with inoculum produced from fresh or preserved faeces collected from sheep or cattle. Other methods used inoculum from a continuous fermentation containing rumen micro-organisms and enzymes produced by fungi. Another modification was to use gas production as a measure of in vitro digestion. The range of nutritional problems that could be measured by in vitro techniques was extended to include the estimation of voluntary food intake and protein degradation. All these in vitro techniques require standardization using food samples that have previously been analysed in vitro or offered as the sole diet to animals. The relative merits of these two calibration methods are discussed. Special facilities are required for storing and distributing these standard foods.
A review of current nutritional models: what we need to measure
Authors: Cottrill B. R.
Published: June 2019

A common feature of nutritional models developed in the last three decades is that estimates of energy and protein are generally made independent of each other, even though interactions between them are recognized.

Most of the energy systems have adopted metabolizable energy (ME) or net energy (NE) as the unit for energy evaluation. Accurate measurement of the ME content of a food requires in vivo digestibility measurements using cattle or sheep, with methane losses either measured or predicted. This approach is clearly unsuitable for routine food evaluation and most systems predict the ME content from chemical analyses, using regression equations derived from calorimetric measurements.

The new generation of protein systems recognize the need to consider, separately, the energy and nitrogen requirements of the rumen micro-organisms and the protein requirements of the host animal. Despite this common base, systems differ markedly in estimates of energy supply to rumen bacteria, the degree to which dietary protein is degraded in the rumen, microbial protein yield and the digestibility of the microbial and undegraded dietary protein.

Although empirically based, current protein systems contain dynamic elements relating to rates of fermentation and protein degradation. In most cases, data have been derived using the in situ nylon bag technique, although this has major limitations. Recent developments in the gas production technique suggest that this approach has the potential for describing fermentation and degradation rates of individual foods.

To be effective, energy and protein systems need to describe foods in units that are both easily understood by non-specialists and can be measured using procedures that are rapid, reliable and cost effective. Near infra-red reflectance spectroscopy (NIRS) can be both rapid and cost effective and there is evidence that it may be able to predict not only proximate analyses but also dynamic characteristics of foods.
A comparison between in vitro digestibility, in situ degradability and a gas production technique for predicting the in vivo digestibility of whole-crop wheat
Authors: Adesogan A. T. , Owen E. , Givens D. I.
Published: June 2019

Several published reports on the nutritive value of whole-crop wheat (WCW) have been based on estimations from laboratory techniques, some of which were developed for grass silage. However, there is little information on the accuracy of such estimations. Therefore the aim of this study was to evaluate the suitability of predicting the in vivo digestibility of WCW from various less animal-dependent techniques.
Effect of days of regrowth of ryegrass(Lolium perenne)on fermentation characteristics: comparison of the nylon bag and gas production techniques
Authors: Chilibroste P. , Tamminga S. , Williams B. A.
Published: June 2019

The nylon bag technique (NBT) has been used widely to characterize the washable (W), insoluble potentially degradable (D) and insoluble non-degradable (U) fractions of grasses (e.g. van Vuuren, 1993) and concentrates (Tammingaet al., 1990). Recently the gas production technique (GPT) has been proposed as a method to evaluate the fermentation characteristics of different foods (Theodorouet al., 1994). Both techniques have shown good correlation with dry matter intake (Khazaalet al., 1993). One of the potential advantages of GPT over NBT is the ability to differentiate fermentation patterns (Grootet al., 1996) that might be related to changes in food composition. This trial was part of a larger grazing experiment and aimed to compare GPT and NBT when applied to samples of ryegrass at different ages. A specific objective was to determine whether or not GPT could extract more information concerning the fermentation patterns of different ryegrass fractions and how these patterns changed as a result of plant maturity.
The development, use and application of the gas production technique at the DLO Institute for Animal Science and Health (ID-DLO), Lelystad, The Netherlands
Authors: Cone J. W.
Published: June 2019

At the DLO Institute for Animal Science and Health (ID-DLO) in Lelystad a fully automated time related gas production apparatus has been developed, using sensitive electronic pressure transducers in combination with electric micro-valves to release overpressure during the incubation. In this very sensitive system, no gas accumulation and pressure build up takes place. Each valve opening represents a known amount of gas, set at about 0-5 ml. By recording each valve opening the kinetics of degradation can be studied. Routine analyses are performed with rumen fluid from wether sheep, diluted with buffer (1 volume rumen fluid/2 volumes buffer). The gas production profiles are fitted with a multi-phasic model, which exists for most foods of three subcurves. It is shown that the first subcurve of gas production is caused by fermentation of the soluble fraction of a food, whereas the second subcurve is caused by fermentation of the non-soluble fraction. The third subcurve, starting after about 15-20 h of incubation, is not related to fermentation of the substrate, but is caused by gas production in the rumen fluid itself, as it is also observed in rumen fluid without substrate. It is discussed whether gas production profiles should be corrected for a blank or not. Gas production profiles of substrates with a high content of protein should be corrected for ammonia synthesis, as the ammonia inhibits the release of gas from the saturated carbonate buffer. The used gas production technique and the used three-phasic curve fit model show a high relationship with existing food evaluation techniques, like the Tilley and Terry technique and the nylon bag technique. Comparing the gas production technique within vivodata has only been done with a very limited number of samples. At ID-DLO the gas production technique is used at present as a research instrument to study the fermentation characteristics of ruminant foods, the technique is used in breeding programmes of grass and maize, to search for optimal degradable genotypes, and in silage research. Moreover, the technique is used to study rumen physiology, with special emphasis on carbohydrate and protein fermentation and the balance between both. The gas production technique proved to be a cheap and accurate technique to determine differences in fermentation kinetics. The gas production equipment cannot only be used to study the fermentation in the rumen but can be used to study all kinds of fermentation, such as colon fermentation in all kind of animals and humans.
Thein vitrogas production characteristics of whole roughageversusextracted neutral-detergent fibre and their implications for analysing the fermentation of cell solubles by a differential approach
Authors: Blümmel M. , Makkar H. P. S. , Becker K.
Published: June 2019

The separation of forages into a soluble fraction like cell contents and into an insoluble matrix like cell walls is an initial step in forage evaluation. Further analysis can be applied to study fermentation characteristics of soluble and insoluble fractions. Unfortunately, most laboratoryin vitrotechniques quantify incubation insoluble residues and are therefore inappropriate for the examination of food solubles.In vitrogas methods (for example Menkeet al., 1979) reflect the production of short chain fatty acids (SCFA) and are therefore free of the disadvantages associated with gravimetric methods. However, it was recently pointed out that an inverse relationship may exist between SCFA production and microbial biomass yield (for review see Blümmelet al., 1997a). These authors suggested combiningin vitrogas measurements with the quantification of substrate concomitantly degraded to calculate a partitioning factor (PF). This factor reflects the substrate-dependent variation in SCFA production and microbial biomass yield; the factor (PF) was shown to be valuable in voluntary food intake (DMI) predictions (Blümmelet al., 1997b). In the work presented here, the rate and extent of fermentation of whole roughages and extracted neutral-detergent fibres (NDF) of 54 roughages were examined in an in vitro gas test. The dry-matter degradability of extracted NDF was also quantified and the partitioning factor for NDF (PFNDF) was determined. The relevance of these findings for the analysis of extracted NDF and cell solubles is discussed and their implications for the prediction of DMI of roughages by gas tests are addressed.
Use of the gas production technique to investigate responses of supplementing low quality forages. 1. In vitro interactions
Authors: Wood C. D. , Murray A. H. , Moss A. R. , Givens D. I.
Published: June 2019

Nitrogen-deficient fibrous crop residues are widely used as basal diets in less developed countries, particularly in dry seasons when alternative foods are often in short supply. One approach to improving animal performance on crop residue based diets is to include a supplement of improved quality food to provide fermentable protein and energy. There are no established in vitro methods for investigating interactions between foods but the in vitro gas production method shows promise in this regard (Prasad et al., 1994). This paper describes the interactions observed in vitro; an accompanying paper (Murray et al., 1998) describes in vivo responses to supplementation and relationships between in vitro and in vivo data.
Application of an in vitro gas method to understand the effects of natural plant products on availability and partitioning of nutrients
Authors: Makkar H. P. S. , Blümmel M. , Becker K.
Published: June 2019

In vitromethods for laboratory estimation of food degradation are important tools for nutritionists.These methods either measure substrate disappearance by quantifying incubation residues or record fermentation products such as microbial biomass, short-chain fatty acids (SCFA) or gas volume (Blümmel et al., 1997a). Recently, the surge of interest in the efficient utilization of roughage diets has caused an increase in the use of gas methods because of the possibility of estimating the extent and rate of degradation in one sample by time series measurements of the accumulating gas volume. We combined gas measurements with residue determinations (truly degraded substrate) or microbial mass determination after fermentation to study the effects of natural plant products, in particular tannins and saponins, on the availability and partitioning of nutrients.
Net alkali requirement of foods of different acidogenicities in a continuous culture system
Authors: Wadhwa D. , Dewhurst R. J. , Dhanoal M. S. , Borgida L. P.
Published: June 2019

Maintaining blood pH within a narrow range is the first priority of an animal compared with the other body functions (Erdman et al., 1982). Under normal forage feeding conditions, maintenance of rumen, blood and cellular pH within safe ranges poses no problem for the animal. However, the inclusion of high levels of readily fermentable carbohydrates is often necessary to meet the energy requirements of high producing ruminants. Unfortunately, these foods can result in low rumen pHs which can have adverse effects on animal health and performance. When saliva flow is inadequate to counteract excessive ruminal acidity, the use of buffers may be justified. The in vivo studies reviewed by Muller and Kilmer (1979) have shown that the responses to the addition of buffers to dairy cow rations has been variable and inconclusive.

Part of the reason for this uncertainty is because buffer requirements cannot be accurately predicted from the chemical composition of foods, since measurements such as buffering capacity (BC) take no account of changes during fermentation such as the production of volatile fatty acids (VFA), ammonia and the disappearance of the fibre which confers BC. An in vitro approach was adopted for this work since it is difficult to conduct in vivo experiments in this area, owing to the health risks to cows as well as difficulties in distinguishing diet effects because of the strategies employed by cows to overcome excess acidity (e.g. eating rate, salivation, rumination).
Integration of in vitro parameters by mechanistic modelling to predict recycling of microbial nitrogen in the rumen
Authors: Dijkstra J. , France J. , Tamminga S.
Published: June 2019

In protein evaluation systems for ruminants, the microbial protein supply is calculated from the amounts of rumen degradable organic matter and nitrogen (N) using empirical equations. A variable part of the rumen synthesized microbial protein does not reach the duodenum but is recycled within the rumen (review Firkins, 1996). Since energy is required for its re-synthesis and degraded microbial protein is subject to deamination, the efficiency of substrate conversion into microbial protein in the rumen is affected by microbial recycling. Rumen protozoa have a major impact upon this recycling through engulfment of micro-organisms and autolysis. In vitro, bacterial protein breakdown is proportionately reduced by some 0·9 upon removal of protozoa (Wallace and McPherson, 1987). Defaunation of the rumen increases the efficiency of microbial protein synthesis in vivo significantly (review Jouany et al., 1988).
Current and future potential of alternative techniques
Authors: Givens D. I. , Gill M.
Published: June 2019

Ruminant animal production faces numerous challenges and it seems that both economic and biological benefits will be derived from moving food characterization from simple energy and protein-based approaches to those which assess nutrient supply in some detail. In vitro systems will need to reflect this change and this paper considers in particular, the need for estimations of rumen volatile fatty acids and microbial protein supplies. Emphasis is placed on the possibility that in vitro techniques can be used to provide biochemical data which can themselves be used in mathematical models of wider processes. This paper also examines the need for in vitro techniques to reflect the microbial!animal response to the physical structure of foods and also the requirement for in vitro approaches which ask why a food has a certain value rather than simply what the value is. In vitro techniques also have a substantial role outside the digestive tract in predicting factors such as voluntary food intake and some aspects of tissue metabolism and some of these aspects are considered. Tor practical application in vitro techniques will need to provide value for money and be compatible as parameters in mathematical models to have an impact at farm level. In this regard physical in vitro techniques such as NIRS seem to have enormous potential.
Comparison of five models used to describe gas accumulation profiles in the gas test method with horse caecal fluid as inoculum
Authors: Macheboeuf D. , van Milgen J.
Published: June 2019

The in vivo organic matter digestibility (OMD) in ruminants can be predicted with the gas test method by the amount of gas produced after 24-h fermentation (Menke et al., 1979). Mathematical models can also be used and can provide useful information concerning the kinetics of fermentation. In ruminants, various models have been used to fit fermentation profiles. The early models are based on first-order kinetics with a constant fractional rate of fermentation (Ørskov and McDonald, 1979; Khazaal et al., 1993). Recently, more sophisticated models have been used to describe gas production kinetics obtained from new automated gas production equipment (Theodorou et al., 1995; Cone et al., 1996). The aim of this study was to compare the relevance and the accuracy of five models for describing gas production kinetics and for predicting the organic matter digestibility (OMD) of forages in horses.
Utilization of the gas test method and horse faeces as a source of inoculum
Authors: Macheboeuf D. , Jestin M. , Martin-Rosset W.
Published: June 2019

The gas test is commonly described as a simple, rapid and cheap technique for predicting the energy value of forages but it requires animals fitted with a canula. In horses, this method can be implemented with caecal fluid as an inoculum to predict the organic matter digestibility (OMD) of forages (Macheboeuf et al., 1998). In the present work, as bacterial content of faeces was known to be very high (Meyer et al., 1993), the use of faeces as a source of inoculum for predicting OMD of forages in horses was studied.
The effect of bromoethanesulphonic acid on gas production during an in vitro rumen fermentation
Authors: Davies D. R. , Bakewell E. L. , Leemans D. K. , Merry R. J.
Published: June 2019

Pressure transducer technology to measure gas production from microbial ecosystems has been utilized in a number of ways but predominantly for food evaluation. The approach also has considerable potential to increase our understanding of, and ability to manipulate, the rumen microbial ecosystem, but most research to date has concentrated on measurement of total gas production and not composition. The aim of this study was to extend the scope of the gas production technique to the quantitation of component gases, whilst investigating ruminal gas production in the presence and absence of methanogens.
Differences between fermentative abilities of rumen fluid from buffalo and dairy cows to measure cumulative gas production
Authors: Calabrò S. , Williams B. A.
Published: June 2019

Inter- and even intra-species variability exists in the ability of rumen inocula to digest forages using in vitro techniques. Differences in fermentation patterns between animal species may be due to the presence of different species within the microbial populations and/or to the fermentative capacity of the microflora (Sunvold et al., 1995). Several authors have reported that the host species affects the rumen microflora which therefore influences the in vitro activity of rumen fluid, even if two host species are given the same diet. Grant et al. (1974) concluded that after a sufficiently long adaptation period to the diet, there was no longer any significant difference between the rumen fluid from buffalo and cows. However, the results obtained by other authors (di Leila et al. 1995; Puppo et al., 1995) are in disagreement with these findings. The in vitro cumulative gas production technique (Theodorou et al., 1994), is increasingly being used as a method of food evaluation, by comparing the fermentability of different foods. One of the greatest sources of variation for this kind of method is due to differences in inocula. An experiment was carried out to determine whether rumen fluid from buffalo and cows given a similar diet, led to similar results for the evaluation of the same foods.
Method for measuring gas production kinetics
Authors: Mertens D. R. , Weimer P. J.
Published: June 2019

Methodology can play a critical rôle in the measurement of digestion kinetics, especially when the objective is to define kinetic parameters for use in formulating rations or modelling animal responses. Measurement of gas production kinetics provides the opportunity to evaluate the rate of digestion of the soluble, more rapidly fermenting fractions of foods but has the potential for being more sensitive to the in vitro procedure used. Differences among procedures that have little impact on digestion of dry matter after 48 h of incubation, may have dramatic effects on fermentation of soluble matter during the first 20 h. Our objective was to develop a method for measuring the kinetics of gas production that would minimize any detrimental effects associated with the in vitro system and provide estimates of digestion kinetics that can be used to both describe foods for ration formulation systems and provide parameters for models of ruminal digestion.
A comparison of the suitability of different models for describing the gas production kinetics of whole-crop wheat
Authors: Adesogan A. T. , Owen E. , Givens D. I.
Published: June 2019

Menkeet al. (1979), Beuvinket al. (1992) and Theodorouet al. (1994) developed techniques for measuring the time course of gas production of foods fermentedin vitrowith rumen fluid. These techniques require description of the fermentation profile with an appropriate mathematical model. Although several authors have used these techniques to study the ruminal fermentation of foods, little information is available on the suitability of the model chosen for describing the fermentation profile of the food under study. In this study, the models of Ørskov and McDonald (1979), Franceet al. (1993) and Beuvink and Kogut (1993) were fitted to thein vitrogas production profiles of 10 whole-crop wheat (WCW) forages (cv.Slepjner) to determine the model most suited to describing the data.
The use ofin vitrogas production to evaluate rumen fermentation of leaves of 24 browse species indigenous to semi-arid areas of Zimbabwe
Authors: Ndlovu L. R. , Hove L.
Published: June 2019

Browse species are important food resources in semi-arid areas, especially during the dry season when the nutritive value of grass is at its lowest. However, browse plants often contain secondary plant compounds which limit their nutritive value. Proanthocyanidins (PAs) (also called condensed tannins) and related flavonoids are a common constituent of woody plants in tropical regions (Mangan, 1988). PAs cause a bitter and astringent taste which lowers food palatability and they also lower the digestibility of proteins and carbohydrates (Jacksonet al., 1996). PAs also interfere with current chemical methods that are used for estimating nutritive value of foods (Reed, 1995). Biological assays, especially ,in vitrotechniques, have a potential to reflect better the nutritive value of foods that contain PAs. Thein vitrogas production technique has been found to reliably predict the nutritive value of temperate forages (Makkaret al., 1996). There has been limited research on its efficacy with tropical forages. The experiment reported here was conducted to test the hypothesis that gas production of tropical browse species reflects their content of fibre, protein and/or PAs.
In vitro rumen degradation of legumes in south Sumatra, Indonesia
Authors: Fariani A. , Warly L. , Ichinohe T. , Fujihara T.
Published: June 2019

Legumes have a significant role in many farming systems of the tropics and subtropics through their contribution to enhanced nutritive value of the animal diet, biological nitrogen fixation and landscape stability (Humphreys, 1995). The great potential of legumes to increase productivity of livestock is being related with their high content of nutrients, especially protein and other nutrients often deficient in grass or low quality hay diets for ruminants. In Indonesia, legumes are often used for replacement of costly concentrate in ruminants diets. Norton and Poppi (1995) reported that quality of tropical legumes varies between and within species but is generally higher than that of tropical grasses. It is well known that the major factors limiting intake and digestibility are those associated with rate and extent of forage degradation by microbial and physical factors in the rumen, primarily the amount of cell wall constituents and the extent of lignification. Association of polysaccharides of cell wall with lignin hinders attack by microbial enzymes and prevents the physical attachment of bacteria to the cell wall. Menke et al. (1979) reported that the amount of gas released when a food is incubated in vitro in the rumen fluid, is also closely related to digestibility of the food and could be used to predict food intake. There is very little information available on the rumen degradation characteristics and in vitro gas production of the tropical legumes. Objectives of the present study were to assess differences in in vitro degradation and gas production between five commonly used legumes in south Sumatra, Indonesia.
Use of an in vitro gas production method to study kinetics of rumen dry matter degradation of forages
Authors: Dhanoa M. S. , Tanner J. C. , Owen E. , Theodorou M. K. , Winugroho H. M.
Published: June 2019

In addition to assessing rate and extent of gas production from fermenting forages in vitro with rumen micro-organisms, gas production methods (e.g. Theodorou et at, 1994) may be used also to study the degradation kinetics of forage dry matter and its fractions. As the substrate dry matter can be lost only through fermentation or solution, this removes the error inherent in the polyester bag method caused by fine particle losses from bags being deemed part of the ‘soluble’ fraction.

The pressure transducer technique (PTT) of Theodorou et al. (1994) was used to measure gas production from nine tropical forage samples (Table 1). Nine bottles were prepared from each of the forage samples. Two bottles of each forage were harvested after 8, 24 and 48 h of incubation and a further three bottles at 72 h, to determine dry matter (DM) and organic matter (OM) losses. The same nine forages were assessed using the polyester bag method (Mehrez and Ørskov, 1977) to obtain DM and OM disappearance after rumen incubations of 4, 8, 24, 48 and 72 h. The soluble fraction was determined by hand washing. The reproducibility of measured losses, at given times, was examined using concordance (rc) correlation (Lin, 1989) and mean square prediction error (MSPE, Bibby and Toutenberg, 1977). Also the simple exponential model was used to estimate the fractional rate of DM degradation (kd) and asymptote A (%) for each forage and the values obtained using PTT (kd,ptt) and in situ (kd,bag) compared using rc and MSPE.
Use of the gas production technique to investigate responses of supplementing low quality forages. 2. In vivo interactions and comparison with in vitro parameters
Authors: Murray A. H. , Moss A. , Wood C. D. , Givens D. I. , Gill M.
Published: June 2019

Ruminants in many less developed countries may consume poor quality roughages such as straws, stovers and senescent native pasture as a major part of their diet, particularly during the dry season when high-quality forages are in short supply. The majority of these roughages are high in fibre, low in protein and the intake of digestible nutrients often is not enough to meet maintenance requirements. Intake and digestibility of poor-quality roughages may be increased by supplementation. The response to supplementation can be attributed to an increase in the supply of nitrogen and/or readily fermentable carbohydrate, resulting in an increase in rumen cellulolytic micro-organisms and therefore enhanced fibre degradation.
Screening of anaerobic gut fungi using a pressure transducer
Authors: Zhu W.-Y. , Theodorou M. K. , Nielsen B. B. , Trinci A. P. J.
Published: June 2019

The growth of gut anaerobic fungi is usually determined in batch culture by gravimetric measurements of dry-matter (DM) loss, or by quantification of fermentation end-products (Loweet al., 1987). These techniques involve destructive sampling of the cultures and require many replicate cultures in time-course experiments. Moreover, techniques using DM loss are only able to measure the end-point of degradation of substrate and cannot follow the growth over the entire fermentation period. Using a pressure transducer, Theodorouet al. (1994) developed a simple and sensitive gas production procedure to determine the fermentation kinetics of ruminant foods. This procedure can also be used to follow the growth of anaerobic fungi on soluble and particulate substrate in batch cultures Theodorouet al. (1995).
A study of the inter-laboratory variation in results obtained using the gas production technique
Authors: Rymer C. , Huntington J. A. , Givens D. I.
Published: June 2019

The gas production (GP) technique has been developed at a number of laboratories throughout the world as a means of providing information on the rate and extent of the rumen fermentation of foods. However, each laboratory has developed its own method for obtaining a GP profile. The incubation may occur in gas-tight syringes (e.g. Hidayat et al., 1993; Khazaal and Ørskov, 1994) or in culture bottles using pressure transducers that are either manually operated (Theodorou et al., 1994) or automated (e.g. Pell and Schofield, 1993; Cone et al., 1996). Clearly, the method adopted to measure gas production could have quite a significant effect on the profile obtained. In a previous study (ring test 1; J. A. Huntington, unpublished) identical samples of five different foods (barley, soya-bean meal, ‘poor’ hay, ‘good’ hay and cellulose) were supplied to eight different laboratories. Each laboratory obtained GP profiles of each food using their own particular technique. These were then fitted to the model proposed by France et al. (1993). As might be expected there was quite substantial variation between laboratories. It was therefore decided to repeat the study (ring test 2) but to adopt a more standard procedure to determine the extent of variability between laboratories that is inherent in this technique.
Protein degradability estimated by tiolic enzymes
Authors: Sarubbi F. , Infascelli F. , di Lella T.
Published: June 2019

New feeding systems for ruminants are based on the estimation of the quantity of protein that can be absorbed by the small intestine. This protein has two origins: dietary or microbial. The measurement of food protein which escapes rumen degradation is probably the major element in the evaluation of food protein value. The in situ incubation in nylon bags (Ørskov and McDonald, 1979) is the technique widely utilized to determine rate and extent of protein degradation. However, the technique is difficult to manage as it requires cannulated animals and can furnish reproducible data only utilizing standardized procedures. Although it is possible to standardize the amount and particle size of food sample, bag characteristics, incubation times and calculation model, it is, on the other hand, very difficult to standardize the basal diet (in our opinion to evaluate the diet only in function of forage/concentrate ratio and crude protein content is inadvisable). Thus for many years various alternative methods which are easier to manage and to standardize (chemical, enzymatic and microbiological procedures) have been developed (Nocek, 1988), to replace the in situ method. The most commonly used enzyme is an endoprotease from Streptomyces griseus (Krishnamoorthy et al, 1983; Poos-Floyd et al., 1985; Aufrère et al, 1991, Infascelli et al, 1993). However, some of the authors (Infascelli et al., 1993 plus Poos-Floyd et al., 1985) agree that this bacterial protease is of little consequence when predicting protein food degradation due to its unspecificity. In addition Poos-Floyd et al., 1985) suggest discarding the endoprotease from Streptomyces griseus due to the variability of results. On the contrary, the latter authors, evaluating rumen protein escape and proportion of degraded nitrogen (N) with enzymatic methods contemporarily, found ficin, a tiolic enzyme, preferable. Recently, Tomànkovà and Kopêcný (1995) have developed a method using another tiolic enzyme, bromelain, to predict rumen protein degradability. Kosmala et al. (1996) in agreement with Poos-Floyd et al. (1985) indicate ficin as the protease to estimate rumen degradability. Because these enzymes allow measurement of crude protein solubility at fixed incubation times, we think that the latter should not be necessarily correlated with the effective degradability that originates from combining degradability kinetics with rumen outflow rate. Thus, the aim of the present work was to compare the bromelain and ficin methods for estimating N solubility, particularly with regard to the variability of results.
Chemical composition, dry matter and crude protein digestibilities of some tropical browse plants estimated in vitro
Authors: Shayo C. M. , Udén P.
Published: June 2019

Browse plants are generally regarded as important food resources for ruminants in the tropics due to their high levels of nitrogen. Particularly during the dry season livestock eat browse which may contain considerable amounts of phenolic compounds including tannins at levels of up to half of the dry matter (Reed, 1986). Tannins are known to react with proteins to form rumen undegradable or totally indigestible complexes.

A uniform food fraction is assumed to have the same true digestibility irrespective of source and level in the food. In the test of uniformity developed by Lucas (1964) and applied by Van Soest (1967) the digestible fraction per unit food is regressed upon its concentration in the food. The slope of the line gives its true digestibility, the intercept, the potential metabolic fraction and the variation around the regression line explains the extent of uniformity of the fraction.
Effect of nitrogen form on growth of rumen micro-organism in vitro
Authors: Carro M. D. , Miller E. L.
Published: June 2019

Rumen microbes utilize mainly ammonia as a nitrogen (N) source for their growth but some species also use a variety of amino acids (AA) or peptides. Several studies have shown both an enhanced fibre digestion and efficiency of rumen micro-organisms when N sources such as AA, peptides and protein were provided in addition to ammonia (Griswold et al.,1996). However, no difference either in digestion or in growth of rumen microbes was found in other in vivo(Fujimaki et al.,1989) and in vitro (Kernick, 1991) studies. The objective of this experiment was to investigate the effects of protein, peptides, AA and ammonia on microbial growth and fermentation of an all fibre basal diet in a semicontinuous culture system (RUSITEC; Czerkawski and Breckenridge, 1977).
Near infrared reflectance spectroscopy wavelengths for selecting barley for the genotypic feeding value of its straw
Authors: A. V. Goodchild  , F. J. El Haramein  , S. Ceccarelli  , E. F. Thomson
Published: June 2019

In the semi-arid parts of west Asia and north Africa, barley straw (Hordeum vulgareL. subsp. vulgare)and cereal stubbles provide between one-quarter and one-half of the metabolizable energy (ME) offered to sheep. In barley straw, voluntary straw dry-matter (DM) intake (VSI) is a good predictor of body weight gain (R2 = 0.85; data of Capper et al., 1989). This varies according to location and year (CV = 0.30 to 0.40) and varies genetically, with an average genotypic CV of 0.07, which can exceed 0.10 in wet years. Genotype X environment interactions in VSI are important (Table 1).

A genetically high VSI is advantageous in cool, wet, favourable growing conditions, when VSI is normally low. In drought conditions, VSI is high, genetically varies relatively little (Table 1) and is less important for the farmer than straw and grain yields. Barley breeders working in drought-prone environments prefer to do most of their selection for yield in dry conditions (Ceccarelli, 1993). Breeders are increasingly selecting for high VSI but wish to focus their testing plots in dry areas. Therefore they need indirect tests that indicate the nutritive value of straw when it is grown in wet environments.
Modification of an in vitro batch culture technique to improve precision in long-term studies
Authors: Hickey M. C. , Moloney A. P. , O'Connell M. , Connolly J.
Published: June 2019

In vitro techniques have been developed to facilitate the measurement of nutritional variability amongst food. Many kinetic studies have utilized the modified Tilley and Terry technique, with long-term incubations carried out in Erlenmeyer flasks. These are inefficient in utilizing incubator space for large scale studies. However substitution of Erlenmeyer flasks with tubes as fermentation units leaves the system prone to ‘bridging’, the formation of dense mats of forage particles by entrapped gas, above the level of the media in a fermentation unit. The objective of experiment 1 was to establish an effective incubation technique to eliminate the random variation caused by bridging.
Prediction of 48 hin situdegradability from chemical analyses andin vitrofermentation of sugar cane bagasse treated with varying levels of electron irradiation and ammonia
Authors: Vitti D. M. S. S. , Abdalla A. L. , Filho J. C. S. , del Mastro N. L. , Mauricio R. , Owen E.
Published: June 2019

Sugar cane bagasse is produced in large quantities in Brazil. The cultivated area of sugar cane in recent years has been around 4.2 X 106ha/year, with a production of about 270 X 106t/year of cane. As each tonne of cane produces around 300 kg of bagasse by-product, a large quantity of bagasse is generated.

Bagasse is of low dry matter (DM) digestibility (about 250 g/kg), because of lignification. Efforts have been made to improve the digestibility of bagasse using treatment with chemicals (sodium hydroxide, ammonia) or steam (Abdallaet al.,1990). Although steam and pressure treatments have improvedin situdegradability, intake and digestibility in cattle were disappointing (Melloet al, 1989). Recently treatment of bagasse with irradiation and ammonia have been investigated.
A survey of some in vitro methods used for animal nutrition research and extension work in Europe: the differences between the references and the truth
Authors: Mills C. R.
Published: June 2019

As animal nutritionists are generally very cautious about using chemical analysis only for defining nutritional needs for livestock and as in vivo experiments are long, costly and subject to animal welfare legislation, much emphasis is placed on various in vitro analyses which are often regarded as being very informative in the absence of in vivo data. In vitro analyses may be applied to dry- (DMD) and organic-matter (OMD) digestibility and crude protein (CP) degradability (DG) and may involve ‘live’ cultures such as rumen fluid or gastric juices or ‘dead’ extracts containing enzymes. As part of an EU-funded Concerted Action (see Acknowledgements), a survey of the methods adopted for in vitro determinations (in vitro OMD, in vitro DG) for ruminants, pigs and poultry is underway: this paper presents a progress report of the information received to date concerning ruminant methods.

The participants in the Concerted Action were asked to provide details of the in vitro methods actually in use in their countries, with particular attention to the methods used by the so-called Feed Information Centres (i.e. Feed Evaluation Units) for routine analyses (i.e. not experimental work). The participants supplied details of modifications and/or references to methods and this information was collated and circulated for checking and comment.
Food production — the price being paid by farm animals
Authors: Ward L. G.
Published: June 2019

There is varying understanding about life for farm animals. The majority of farm animals have gone from the land, only to be caged, crammed and confined behind the closed doors of the factory farm — battery hens sentenced to remain for life in wire cages, broiler chickens reared in overcrowded conditions and pigs tethered and confined in narrow stalls or in equally narrow farrowing crates. Other farm animals are sent abroad to the cruel veal crate system of continental Europe or to abattoirs where welfare standards, both during transportation and at the time of slaughter, are often appallingly low. Many of the animals slaughtered in Britain, or for the live export trade, are processed through live auction markets. A recent investigation revealed many instances of infringements of the regulations governing the treatment and welfare of animals at markets. The controversy over BSE and the cloning and genetic engineering of farm animals have all resulted in close scrutiny and inquisitions by the public into the conditions in which our farm animals are reared, treated and slaughtered. Those involved in the food industry and also those who care about the welfare of animals and recognize their sentiency must take action to ensure that the animals are reared with due thought to their behavioural needs and well being and, when the time comes, granted a quiet and humane death. For far too long in food production programmes farm animals have paid a heavy price in suffering. From birth to death, farm animals must be treated humanely and with respect.