There is an increased range of alternative forage available to Iranian dairy farmers. Improvements in breading, growing, harvesting and storage technology in this area have helped the expansion of alternative to whole crop cereals. Whole crop cereal silages are very flexible, allowing the decision to have the crop ensiled as fermented whole crop. Incubation of feeds in nylon bags in the rumen of fistulated ruminants have been used to evaluate the extent of digestion. The objective of the present study was the determine chemical composition, dry matter and crude protein degradability coefficients of whole barley, triticale and maize silages treated with urea.

The enzyme polyphenol oxidase (PPO) may be responsible for increases in both dietary-nitrogen utilisation and the concentration of polyunsaturated fatty acids in ruminant products when animals eat red clover (Lee et al. 2004). The enzymatic reaction requires the presence of oxygen and therefore is assumed to be inhibited in the anaerobic rumen. However, little information exists as to the concentration of oxygen in boluses and whether this could sustain the aerobic enzymes activity in the reticulo-rumen. This study investigated the concentration of oxygen in grass-boluses measured in vitro or in vivo in the rumen of two rumen fistulated cows.

The use of by-product in animal nutrition is necessity since it may increase the availability of feed for animal and avoid accumulation that contributes to environmental problems. Sugar cane bagasse and pith, by- product which leave the last processing stage of the sugar mill (bagasse) and passed through rotary sieves to separate fine particle (pith), are the most abundant by-product in Iran. The low digestibility, high lignin and very low content, are considered the main reasons for unsatisfactory performance of animals fed this roughage. Steam-pressure treatment cleavage the bounds between lignin and the other component of the cell wall, in order to improve it's degradability by enzymes of the rumen microbial ecosystem. The objective of this work was to evaluate the chemical composition and in situ degradability of sugar cane pith treated by steam at high pressures.

There is increasing interest in the Cornell Net Carbohydrate and Protein System (CNCPS) for rationing cattle. Crude and digestible protein determinations do not completely account for the dynamics of ruminal fermentation and potential loss of nitrogen as ammonia (Sniffen et al 1992). When measured data on the protein and carbohydrate contents of feeds were used, the predictions of the performance of dairy, beef and dual-purpose cattle were more accurate than when tabular values were used (Fox et al 2004 ). To obtain the best predictions, the CNCPS model requires an accurate description of the carbohydrate and protein fractions and the unique rates of digestion and passage of individual feed fractions that are being fed. This information can be used as a basis for amino acids absorption. The CNCPS use in Iran is limited because the inputs data is not determined. The present work was carried out to determine nitrogen fractions of some feeds are using in ruminant nutrition.

In addition to environmental and management factors, the degradation characteristics of forages are greatly influenced by both the structure and composition of cells within that structure. In particular, and even when grown under the same environmental conditions, marked difference exists between the tissue composition of C3 (temperate) and C4 (tropical) grasses. This differentiation, a reflection of their origin, is based on the photosynthetic pathways with C3 and C4 grasses using phosphoglycerate and oxaloacetate, respectively as intermediates. C3 grasses tend to have a lower cell wall content which is usually restricted to the stem component and a greater proportion of highly degradable mesophyll tissue. The possibility that C3 and C4 grasses exhibit different degradation characteristics depending on the rumen fermentative environment therefore exists. This is of major importance when it is considered that about 0.15m ha forage maize, a C4 grass, are grown annually in the UK. This study compared the chemical composition and in vitro degradative characteristics of three C3 forages, viz; grass hay (GH), wheat straw (WS) and rice straw (RS) and maize stover (MS) as influenced by incubation medium pH using a 4 x 3 factorial design. .

Brazil has arid regions where livestock production is limited by forage source. However, some native herbaceous browses have a dry tolerance and have been used as animal feeds. Some of those plants have anti nutritional compounds such as tannins that can interfere on intake and digestibility. Tannins have a high affinity to proteins and could make these molecules unavailable for animal. Compounds as polyethylene glycol (PEG) has been used on tannin studies, because it has more affinity with tannins than proteins. Based on that, it is possible to evaluate the nutritive potential of tanniniferous plants, using PEG in gas based techniques for assessing anti nutritional factors in tanniniferous plants for ruminants. The aim of this work was to investigate the biological activity of tannins using the in vitro gas method with the addition of polyethylene glycol (PEG).

Animal production in Brazilian semi-arid north-east is limited by dry-season feed shortage leading to high mortality and low production of the herds. Most of vegetation consists of forage plants with high protein content but low digestibility and high levels of tannins (10%). The aim of this work was to investigate the biological activity of tannins using the in vitro gas method with the addition of polyethylene glycol (PEG).

Evolutionary diets composed solely of grass & hay are rarely able to provide domesticated equidae with the energy required for the athletic performance. Modern feeding practices have dictated that horses with a high-energy demand are fed cereal-based concentrate foods, often with minimal forage inclusion within the diet. Such high starch, low-fibre diets, when fed to excess, are recognised to induce metabolic disorders such as laminitis. Alternative forage sources capable of providing higher amounts of energy would be preferable in some cases, allowing the reliance on cereal diets to be reduced. It has been found that when fed to ruminant animals, ensiled red clover has a higher D-value and leads to an increase in both voluntary feed intake (VFI) & animal production, when compared to grass silage, (Freudenberger et al, 1994; Rutter et al, 1998). Recent studies have shown that when fed to ponies, red clover silage had a significantly higher apparent digestibility & VFI than either grass silage or hay (Hale and Moore-Colyer, 2001). The aim of this study was to investigate the potential benefits of several leguminous forages in their fresh, rather than conserved form, as suitable feeds for horses. Degradation of the fresh products was estimated using in vitro gas production techniques.

Ruminal fermentation produces methane (CH4), which represents a loss of feed energy and a significant source of greenhouse gas. Researches have been searching for ways of inhibiting ruminal CH4 yield and promising results have been achieved in in vitro assays (Hu et al., 2005). The in vitro gas production technique can predict the in vivo enteric CH4 production from ruminants. Our research focused on the effect of 2-Bromoethanesulfonic acid (BES) on gas and CH4 production and microbial variation of Lucerne and Tifton-85 hays fermented in vitro.

The complete hydrolysis of complex structures, such as plant cell walls, requires the application of a range of multifunction enzymes in appropriate quantities. However while xylanase and cellulase activities in the rumen are adequate, such that additional (exogenous) enzymes are not required, their action is restricted due to the close association between cellulose and hemicellulose and other polysaccharides and to extensive substitution. In particular the arabinoifuranosyl residues in the hemicellulose chain form ferulic acid cross-links with lignin, so limiting biodegradability. Thus the so-called minor enzymic activities may be critical in making additional cell wall sites available for microbial attachment and subsequent digestion. To examine this effect the ability of ferulic acid esterase (FAE), which releases ferulic acid, to enhance fibrolytic activity by rumen microorganisms was evaluated in vitro.

Researches worldwide have been studying ruminal methane production in vitro and the in vitro gas production technique has demonstrated an ability to predict the in vivo enteric methane production from ruminants (Getachew et al., 2005; Tavendale et al., 2005). Studies of rumen microbial ecology in animals fed with tannin rich plants have demonstrated that tannins can affect rumen ecology. The objective of this study was to measure methane (CH4) production of Brazilian tannin rich plants incubated in vitro.

The gas production technique has been widely used for evaluation of nutritive value of feeds (Pell et al., 1998) and gas production profile has been shown to have good relationships with VFA produced in the rumen (Blummel and Ørskov, 1993; Brown et al., 2002), as well as neutral detergent fiber (NDF) (R2 = 0.98) (Herrero and Jessop, 1996) and dry matter (DM) disappearance (R2 = 0.95) (Prasad et al., 1994). Carbohydrate portion of each feed is divided into three digestible fractions: The A fraction, containing sugars, short oligosaccharides and organic acids; the B1 fraction, containing starch and pectin; and B2, the digestible fiber fraction (Doane et al., 1998). The objective of this study was to evaluate of nutritive value of some Iranian feedstuffs by using gas production technique.

Whole cottonseed (WCS) is a by-product of the cotton-gin industry. This feedstuff is of significant feeding value for animals. WCS dry matter is high in fat, crude protein and neutral detergent fiber (NRC). The effect of fat on rumen-fermentation characteristics is explained by its detrimental effect on rumen microorganisms (Arieli, 1998). Chalupa et al (1984) found in an in-vitro study that addition of free C18:1, C18:2 and C18:3 to a hay-grain diet decreased the volatile fatty acids (VFA's) concentrations and acetate-to-propionate ratio. In some experiments, WCS had no effect on rumen fermentation. Sklan et al. (1992) found that the acetate:propionate ratio increased with WCS. The aim of this study was to survey the effect of addition of WCS and decreasing dietary CP level on rumen parameters.

Animals grazing on land contaminated with cadmium due to pollution such as sewage sludge application and traffic emissions ingest cadmium adhered to plants and in soil. The effects of cadmium on ruminal enzymes have been investigated (Faixová and Faix, 2002) as have the effects on the bacterial and protozoal fractions of rumen fluid (Forsberg, 1978). These studies used a single cadmium salt, usually for ease of solubility, however, differences in toxicity have been found between cadmium salts (Barrouillet et al., 2001). The aims of this study were to investigate the effects of cadmium salts and of differing concentrations of cadmium on fermentation by rumen microbes in-vitro.

Gas measurement provides a useful data on digestion kinetics of both soluble and insoluble fractions of feedstuffs (Getachew et al. 1998). Carbohydrate portion of each feed is divided into three digestible fraction: the A fraction, containing sugars, short oligosaccharides, and organic acids; the B1 fraction, containing starch and pectin; and B2, the digestible fiber fraction (Doane et al. 1998). The objective of this study was to measure of fermentation parameters of corn silage treated by urea and formaldehyde using gas production technique.

Tropical fodder trees are commonly used as supplement to grass feeding. Usually supplemental foliage is used without any additional energy source. Therefore, the potential of fodder trees to increase microbial biomass production (due to foliage N capture for microbial growth) might not be achieved. In addition, it has been suggested that forage digestibility might be stimulated if an energy source, ideally, locally available, is provided with the foliage. Thus, the objective of the present experiment was to assess the DMD of Leucaena leucocephala and Manihot esculenta (cassava) mixtures, and the in vitro gas production of Leucaena-cassava-grass mixtures.

A vast area in central Iran is desert in which the soil salinity is high. Therefore, plant varieties capable of growing in this area are very limited, the most typical ones which can be used by animals, mainly camel, are Alhogi spp. (AL), Salsola soda spp. (SS) and Shooreh (SH). However, the nutritional value of these plants in terms of their chemical compositions and degradability characteristics is not available. The objective of this study was to determine the chemical composition and extent organic matter (OM) digestion of these plants compared with grass nuts (GN) as a reference feed by using an in vitro method (Rezaeian and Chaudhry 2005).

Forage pollution by lead has been caused by mining, sewage sludge application, nuclear plants and traffic emissions. Animals grazing on contaminated land have a higher exposure to the toxicity posed by contamination adhered to plants and through soil ingestion. Strojan and Phillips (2002) found a decrease in gas production in the presence of lead although other parameters were not measured. The objectives of this study were to investigate the effects of different lead salts and concentrations on microbial activity of rumen micro-organisms in-vitro.

Determining the feed value of local feedstuffs is necessary for the optimum utilization of resources in animal nutrition. Considering climate, plant variety and animal breed, there are many variations among the nutritional value of feedstuffs in any region of the world. The objective of this experiment was to determine the in vivo and in vitro digestibilities and in situ degradability of some local feedstuffs in Tehran province of Iran.

The extent of ruminal forage dry matter digestion is a function of rate of digestion and rate of passage. It is a complex process that is affected not only by the forage composition, but also by the retention time of forage particles in the different segments of the gastrointestinal tract (Noziere & Micalet-Doreau, 2000). A major factor affecting ruminal NDF digestibility of forage is the rate at which the forage passes from the rumen. This is a unique characteristic of individual forages or fibre sources. Daily intake of digestible organic matter is also closely correlated with ruminal retention time for forages and this relation applied to both temperate and tropical feeds. The objective of the present study was to determine the ruminal retention time (RRT) and indigestible dry matter fraction (IF) of various Iranian forages using in situ nylon bag procedure.