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Sayan, Y., Ozkul, H., Polat, M., Capc1, T. and orskov, E.R. 2010. In situ degradation characteristics as predictors of in vivo digestibility and metabolizable energy values of forages and wheat straw. J. Appl. Anim. Res., 37: 77–81. To predict the in vivo dry matter digestibility (DMD), organic matter digestibility (OMD) and metabolizable energy (ME) values of forages based on in situ degradation characteristics, data of Sayan et al. (2004) for 40 samples of 3 forages and wheat straw were used in the study. For determining the degradation characteristics of forages nylon bag technique was used. There was a high (P

The economic turmoil in South-east Asia has had catastrophic effects on the agriculture of the region and has led to widespread famine. Intensive animal production systems have suffered worst because of their almost total reliance on expensive imports of feedstocks. Small integrated farms have fared better, and they should be seen as the model for the agricultural production of the future. Research should be aimed at the support of small farmers, and their use of local feed resources, as well as animals and production systems suited to the locality.

Browse plants play an important role in providing fodder for ruminants in most parts of the World. However, the presence of tannins and other phenolic compounds in a large number of these feed resources limits their utilization as animal feed. This paper presents the nutritive value of some browse species based on their chemical composition (nitrogen, polyphenolics and neutral detergent fibre (NDF) content), dry matter (DM) degradability in sacco and gas production in vitro including the effect of the phenolic binding compound, polyethyleneglycol-4000 (PEG 4000), on in vitro gas production. The browse species evaluated were Calluna vulgaris (heather), Sarothamnus scoparius (broom), Ulex europaeus (gorse) and Chamaecytisus palmensis (tagasaste). The crude protein (CP) content was highest (P < 0.05) in broom (189 g kg−1 DM) followed by tagasaste (175 g kg−1 DM) and gorse pre-flower (168 g kg−1 DM) and the lowest was in heather (98 g kg−1). Heather had the highest (P < 0.05) concentration of the phenolic compounds compared with all the other species. Gorse in-flower contained a higher concentration (P < 0.05) of total extractable phenols (TEPH), total extractable tannins (TETa) and NDF and a lower content of CP than gorse pre-flower which is a reflection of their stage of maturity. As a result, gorse pre-flower had a higher in sacco degradability and in vitro gas production than gorse in-flower. Heather had the lowest degradability values. The ranking order of the browse plants in gas production was gorse pre-flower > tagasaste > broom > gorse in-flower > heather which was similar to their in sacco degradability values. Increasing the amount of substrate incubated slightly depressed the amount of gas produced by the browse plants. The response to PEG treatment increased with increased concentration of phenolic compounds in the browse plants. Thus, in heather, gas production increased by 51% at 12 h of incubation as a result of PEG treatment while the response was zero in the species with a low content of phenolic compounds. The results show that the phenolic compounds depress in vitro gas production and that PEG treatment has a potential for improving gas production and fermentation of feedstuffs high in phenolics due to the binding of the phenolic compounds to the PEG.

Biochemical changes during fasting or the withholding of feed for 5 day were studied in serum of camelids (dromedary camel, llama) and ruminants (sheep, steers). Camels maintained low levels of 13-hydroxybutyrate (BHB) and high levels of glucose but showed some increased levels of non-esterified fatty acid (NEFA) and urea when fasting. Sheep and steers showed a rise in serum BHB and much higher increases of NEFA than camels and llamas. Sheep showed decreased serum glucose. The llama showed some increase in BHB but NEFA was lower than the other three species. The results indicate that camelids have a unique ability to control lipolytic and gluconeogenic activity to prevent or postpone the state of ketosis. Understanding and manipulation of these metabolic mechanisms in cattle and sheep could have great benefit to the livestock industry.

Principles of supplementation are discussed in respect of both, their positive and negative effects on roughage digestion and utilization by ruminants. It is pointed out that negative effects mainly occur when excessively processed concentrate is given in large quantities two times per day. This lowers rumen pH which in turn depresses cellulose digestion and intake of cellulosic feeds, leading to problems of acidosis and secondary ketosis due to off-feed conditions. To a large extent, such problems can be overcome by limited processing and feeding the concentrate mixed with the roughage. Supplements can also have positive effects by alleviating deficiencies such as nitrogen or by providing easily fermentable fiber to increase microbes for attachment to roughages. Supplements can increase microbial protein production and undegraded protein supply. It is emphasized that proper use and management of supplements can make the difference between profit and loss for small farmers.

The changes in urinary and plasma purine derivatives in response to fasting and level of feeding in llamas were examines. In one experiment, four llamas were gradually deprived of feed within 3 days and then fasted for 6 days. Daily urinary excretion of purine derivatives decreased with feed intake and leveled on the last 3 days of fasting at 177 +/- 26 mumol/kg W0.75. Allantoin and uric acid comprised 71% and 15% of total purine derivatives, respectively, in both fed and fasted states, but hypoxanthine plus xanthine increased from 9% to 36%. Plasma concentration of allantoin declined with feed intake reduction, but those of uric acid (217 mumol/l) and hypoxanthine plus xanthine (27 mumol/l) remained relatively unchanged. Concentration of uric acid was higher than that of allantoin, probably due to a high reabsorption of uric acid in renal tubules, which was measured as over 90%. In a second experiment, the four llamas were fed at 860 and 1740 g dry matter/d in a crossover design. Urinary total purine derivatives excretion responded to feed intake (10.4 vs 14.4 mmol/d), although the observed differences did not reach significance. Compared with some ruminant species, it appears that the llama resembles sheep regarding the magnitude of urinary purine derivatives excretion but is unique in maintaining a high concentration of uric acid in plasma, which could be part of the llama's adaptation to their environment.

A method is reported for determination of allantoin in urine and plasma based on high-performance liquid chromatography (HPLC) and pre-column derivatization. In the derivatization procedure, allantoin is converted to glyoxylic acid which forms a hydrazone with 2,4-dinitrophenylhydrazine. The hydrazone appears as syn and anti isomers at a constant ratio. These derivatives are separated by HPLC using a reversed-phase C18 column from hydrazones of other keto acids possibly present in urine and plasma and then monitored at 360 nm. All components were completely resolved in 15 min. Both the reagents and derivatization products are stable. Recovery of allantoin added to urine and plasma was 95 +/- 3.7% (n = 45) and 100 +/- 7.5% (n = 64), respectively. The lowest allantoin concentration that gave a reproducible integration was 5 mumol/l. The between-assay and within-day coefficients of variation were 2.8 and 0.6%, respectively.

Publisher Summary The control of rate and extent to which dietary protein and amino acids are degraded in the rumen fermentation is a major determinant of the supply side of the equation. The possible ways of increasing the efficiency of the supply process are examined as well as strategies for correcting amino acid shortfalls. The control of rumen protein and amino acid degradation requires a thorough understanding of the degradative process, particularly peptide and amino acid metabolism. It helps in identifying ways to alter rumen microbial metabolism. Genetic selection or engineering has a bright future in the control of forage-protein degradation. Control of protein loss in the silo demands the attention of scientists where silages are extensively utilized. The current quantitative knowledge of the protein and amino acid needs of the host ruminants is inadequate. The impact of rumen-protected protein and amino acids and other manipulative strategies will be largely unpredictable until this deficiency is corrected.

Without chemical analysis, Blummel and Ørskov (1992) adapted the in vitro gas test (Menke and Steingass, 1988) and used the exponential equation p=a+b (l-e-ct) to describe the kinetics of fermentation of 10 straws. They reported high correlation with animal performance. The aim of the present study was to adopt a similar approach and assess the gas test in comparison with nylon bag for the prediction of intake or DM digestibility of 10 different quality hays.Ten hays consisting of 3 harvesting stages of lucerne (Medicago sativa), sweet clover (Melilotus segetalis), persian clover (Trifolium resupinatum) and Italian rye-grass (Lolium multiflorum). Each hay was fed ad libitum to 4 Merino male sheep and their intake (g dry matter (DM)/day/KgW0.75) and in vivo DMD were recorded.

Monensin and yeast culture are known to alter rumen fermentation. Their modes of action appear to be different, and a recent study showed that the combination of both yeast culture (YC) and monensin stimulated weight gain in bulls by 12-13% over monensin alone (Spedding, 1990). However, Edwards et al. (1991) found no complementary effects between YC and avoparcin when they were combined in a silage diet for steers. In addition to its action in the rumen, monensin is known to affect post-ruminal digestion (Armstrong, 1984). Viable Saccharomyces cerevisiae have been isolated from the duodenal digesta of sheep fed YC (Newbold et al., 1990), suggesting that YC too might have post-ruminal effects. The aim of the current study was to assess the effect of monensin and/or yeast culture in the diet or infused into the abomasum on rumen fermentation and blood parameters, and also on digestive physiology by monitoring plasma gastrin, insulin and CCK-8 concentration.

Extensive hydrolysis of cell wall polysaccharides by rumen bacteria or free enzymes has been reported when lignocellulosic materials had been treated with steam and pressure (Dekker & Wallis, 1983; Castro & Machado, 1989). This has mainly been explained by complete hydrolysis of hemicellulose, lignin depolymerization and redistribution within the cell wall and increasing accessible pore volume by swelling of the cell walls. Physical treatment based on use of steam and pressure alone (auto-hydrolysis) is always associated with the release of toxic levels of furfural and phenolic monomers. These chemicals are able to inhibit the activity of rumen microorganisms, yeasts and free enzymes. To overcome this effect, dilute-acid-hydrolysis at low temperatures and pressures has been proposed (Grohmann et al., 1985). The aim of this study was to evaluate the effect of temperature, sulphuric acid concentration and reaction time on the utilization of treated wheat straw by dilute-acid-hydrolysis, either by rumen bacteria and free enzymes.

Supplements of readly digestible cellulose and hemicellulose enhance fibre degradation by promoting the growth of eellulolytic microbes in the rumen. In the current study supplements of ammonia treated straw were fed to a basal diet of untreated straw and intake, fibre digestion and rumen fermentation assessed.Four mature castrated male sheep weighing 50.5 to 69.6kg and fitted with permanent rumen cannulae were used. The experiment had a 4 x 4 latin square design such that the sheep were fed four diets and measurements taken oyer four periods. Each period consisted of 10 days adaptation and measurements taken for a further 8 days.The diets comprised untreated straw (control) ammonia treated straw (AS) or untreated straw together with 200g AS or 400g AS (200AS and 400AS respectively). Straw was treated with 3.5% ammonia (w/w). Untreated straw was supplemented with 1% urea (w/w). In addition both straws were supplemented with minerals and vitamins. Straw was chopped (4cm screen) prior to feeding. For diets 200AS and 400AS the treated and untreated stsaws were given in seperate troughs.

The removal of ciliate protozoa, or defaunation, results in the establishment of a new ecosystem in the rumen, consisting only of bacteria and fungi. Although extensive research has been done on ciliate-free ruminants, the role of protozoa in the rumen still provokes considerable debate. The diversity of experimental design, such as animal species, defaunation method, and diet could account for many of the differences observed between defaunation studies. Also it is important to examine the stability of the ciliate-free ecosystem. The aim of this study was to investigate changes in rumen fermentation of ciliate-free sheep over a period of one year.Eight male castrated sheep, weighing 60-70 kg, received twice daily 700 g of a diet of hay, barley, molasses, fish meal and vitamins/minerals (500, 299.5, 100, 91 and 9.5 g/kg DM respectively). Four sheep were defaunated by the rumen washing technique (Jouany and Senaud, 1979) and kept in isolated pens while the other four were left faunated with a mixed type A ciliate protozoa population. Rumen samples were withdrawn via the rumen cannula and blood samples were taken from the jugular vein -1, 0, 1, 2, 4 and 6 h after feeding. There were three sampling periods: one month, six months and one year after defaunation.

The rates of disappearance (p) of protein from fish-meal, meat-and-bone meal, soya-bean meal, cottonseed meal, linseed-meal and groundnut-meal were described when nylon bags were incubated in the rumens of sheep and cattle given either barley or dried grass. The exponential equation p = a + b (1 − e−ct),where a, b and c are constants, e is the natural logarithm, and p the amount disappearing in time, t, was used. There was no consistent difference between the degradabilities determined with sheep and cattle. Degradation was finally combined with different outflow rate (k) and the effective degradability (P) was described as the equation P = a + (bc) (c + k) .

Two Friesian cows in their third week, and two other cows in their seventh month of lactation were given abomasal infusion of 0, 350, 700 and 1000 g per day of casein. The casein infusion increased yields of milk, protein and total solids, the increases being much greater in early than in late lactation. Casein infusion did not change the plasma concentration of insulin in early lactation while a linear increase from 9.9 to 24.5 mU 1 −1 was observed in late lactation. This increase was not related to changes in plasma glucose.

New systems for estimating the requirements of ruminants for dietary protein involve separate estimates of the extent to which microbial and undegraded dietary protein meet the animal's net requirements for amino acids. The paper provides a brief review of the factors influencing both the synthesis of microbial protein and the amounts of dietary protein that escape the rumen undegraded. Although quantitative data on many of these factors are now emerging, the extensive nature of most sheep-production systems makes their application in a precise quantitative manner difficult. It is suggested that considerable improvements in production could be achieved by using the principles in a qualitative sense. For low-producing animals such as dry ewes, pregnant ewes up to a few weeks before lambing, and ‘store’ lambs, microbial protein will meet the animal's net requirements for amino-acid nitrogen provided that the animals have not been previously subjected to a specific protein deficiency. In contrast, the maximal yield of microbial protein will not meet the net requirements of high-producing animals, such as young, fast-growing lambs, and ewes in the final few weeks of pregnancy and during early lactation. These animals require protein supplements which at least in part escape degradation in the rumen.

Samples of untreated (US) and ammonia-treated (AS) barley straw of the Corgi variety were either soaked with water, ensiled with grass silage, or treated with alkaline hydrogen peroxide. The degradability of dry matter (DM) in the treated samples and their respective controls was determined by measuring DM loss from samples incubated in nylon bags for various periods in the rumen of sheep. Responses were assessed by using the mathematical model p = a + b (1 − e − ct ), where p is DM loss, ( a + b ) is potential degradability, c the rate constant of DM loss and t is the time of incubation. Soaking and ensilage produced no significant alteration of degradation pattern of DM loss. Treatment of US and AS with alkaline hydrogen peroxide, however, increased potential degradability by 20 and 10 percentage units, respectively. The results show that alkaline hydrogen peroxide is effective in improving the degradability of cereal straws.

When excessively processed cereals are given to ruminants a vast surface area of highly fermentable substrate is exposed to the rumen microorganisms. The subsequent effect on digestion and metabolism will depend largely on whether the cereal based diets are fed as the main or sole part of the diet or whether they are given as supplements to roughage based diets. Given as sole feeds, excessively processed grains can give rise to alterations in carcass quality (soft fat) in lambs, and problems of acidosis and rumenitis. Given as supplements to diets based on roughage, excessively processed grains can seriously reduce the rate of cellulose digestion with a consequent decrease in roughage intake and digestibility. The optimum extent of processing appears to be the minimum required to avoid an unacceptably low digestibility. The processing required is different for small ruminants (e.g. sheep, goats and calves) than for large (e.g. cattle). For sheep, grain should be fed whole; in general, processing does not increase digestibility or food utilization and can result in depressed cellulose digestion and in soft fat. For cattle some processing is required to ensure adequate digestion but the optimum is that required to give entrance through the seed coats to microorganisms and digestive enzymes. New methods, such as chemical treatment of whole grain, have given promising results.

Summary The role of silicaceous spicules in the aetiology of rumenitis in cattle was investigated by feeding diets of pearl barley and cotton fibres, with and without screened debris from barley pearlings. Spicules from barley grain appeared to cause only minor physical damage to the ruminai mucosa. Minor damage is not necessarily negligible, but it is suggested that the findings do not justify the allocation of high priority rating to barley breeding programmes aimed at the elimination of rachilla and lodicule spicules. Multiple inflammatory lesions of the rumen wall were found in sheep fed on a diet of barley to which cut cattle hair had been added, but not in sheep fed on barley alone.

Summary When whole barley grains were incorporated into pellets rather than rolled barley the severity of the pathological changes in the rumen wall was reduced. When unprocessed whole barley was fed, the pH in the rumen was increased and no pathological changes occurred. The rumen walls appeared completely healthy, there was no reduction in the apparent digestibility of the barley and the animal’s performance was unaffected.

In the first part of this chapter the justification for changing the system of protein evaluation is discussed and it is argued that, even if the data are inadequate, new logical concepts based on scientific principles can be introduced provided: (a) that the new system when applied to old data gives a prediction of animal performance as good as, or better than, that given by the older systems; (b) that the new systems encourage research to generate new data in the light of the new concepts; (c) that the system allows for new data to be introduced to increase precision of the systems. The concept of separating microbial and host animal need for protein is discussed and validated with recent data. The importance of protein degradability is discussed, together with methods with which degradability can be measured. It is illustrated that there is not merely a single value for degradability but that this will vary with outflow rates of small particles from the rumen. The inadequacy of microbial protein to meet the protein need of young early-weaned ruminants and high-producing dairy cows is illustrated by recent results.

Summary The recent knowledge on fattening of lambs is discussed with emphasis on feed processing, protein requirement and manipulation of body composition. Processing of concentrate diets should be limited only to that required to ensure maximal digestion. Feeding of whole cereals is usually preferable to feeding of processed grain. Excessive processing of grain leads to problems of rumenitis, acidosis and poor carcass quality. The need for protein in addition to that derived from microbial protein, in the fattening of lambs, depends to a large extent on previous nutrition. Store lambs, having experienced a period of low level or undernutrition, have a greater requirement for undegraded dietary protein (UDP) than well-fed animals at the same live weight. Recent observations have shown that it is possible to utilize stored body fat as a source of energy from which to grow or maintain weight, provided a source of undegraded protein is given. This has practical applications when lambs are overfat at the time of marketing and for extending time of slaughter into the dry season in areas of fluctuating nutrient supply.

Differences in rumen volume can have considerable effects on the digestibility and voluntary intake of ruminants. For instance Mould et al. 1982 showed that cattle in Bangladesh had a much greater rumen volume relative to live weight than reported values of Friesian cattle. They also consume much more straw per unit of live weight than Friesian cattle.Differences between cows in the ability to consume roughage have often been observed. It is however possible that this strategy could be adopted simply by increasing outflow rate and not necessarily by a high rumen volume. Depending on the strategy adopted this would give rise to differences in the digestibility of the roughage consumed.In order to investigate these aspects in more detail, 22 lactating Friesian cows were given doses of Cr-mordanted straw having been ground through a hammer mill with a 2 mm screen. The cows were fed completely mixed diets consisting of 50% ammonia treated straw and 50% concentrate.

Recent work has shown a great variability in the nutritive value of different cereal straws. Tuah et al (1986) examined a number of cereal varieties including barley, oats, wheat and triticale. Ramanzin et al. (1986) examined the extent to which these effects could be explained by differences in leaf:stem ratio and that the nutritive value of leaves were far greater value than straw.

Abomasal infusion of casein has been shown to increase the milk yield, fat yield, protein content and protein yield while no clear-cut effects were observed with infusion of glucose (Ørskov, Grubb and Kay, 1977 and confirmed by Oldham, Bines and MacRae, 1983). Little information is available about the changes in blood parameters with abomasal infusion of glucose or casein. The objective of the present experiments was to relate changes in milk production to blood parameters in dairy cows given casein or glucose as an infusion into the abomasum during early or late lactation.