WO2010089453A1

WO2010089453A1 - Animal feed

Info

Publication number: WO2010089453A1
Application number: PCT/FI2010/050060
Authority: WO
Inventors: Marko Lauraeus; Juha Apajalahti; Ulf Hotanen; Suvi Pietarinen; Kaisa Herranen; Kari Luukko
Original assignee: Upm-Kymmene Corporation
Priority date: 2009-02-06
Filing date: 2010-02-03
Publication date: 2010-08-12
Also published as: FI20095112A; FI122129B; FI20095112A0

Abstract

The present invention relates to animal feed compositions comprising hemicellulose selected from xylan and galactoglucomannan and mixtures thereof,particularly for ruminants and monogastric animals. The invention also relates to the use of hemicellulose selected form xylan and galactoglucomannan and mixtures thereof as a component in animal feeds, in animal feed compositions, as animal feed supplements, as animal feed extenders or as components therein.

Description

ANIMAL FEED

Field of Invention

The present invention relates to animal feeds and particularly to animal feed extenders, animal feed supplements and animal feed toppings for ruminants and monogastric animals. The invention also relates to the use of xylan and galac- toglucomannan as animal feeds and particularly as animal feed extenders, sup- plements and toppings. The invention provides new animal feeds, animal feed extenders, supplements and toppings based on xylan and galactoglucomannan obtainable from natural sources.

Background of Invention

Ketosis is a common disease of adult ruminants and it most often occurs in dairy cows in early lactation, sometimes also in cattle in late gestation. Typically the animal loses appetite and signs of nervous dysfunction, including pica, abnormal licking, abnormal gait, bellowing, and aggression are occasionally seen.

The pathogenesis of bovine ketosis is not completely known, but it requires the combination of intense adipose mobilization and a high glucose demand. Both of these conditions are present in early lactation, at which time negative energy balance leads to adipose mobilization and milk synthesis creates a high glucose de- mand. Adipose mobilization is accompanied by high blood serum concentrations of nonesterified fatty acids. During periods of intense gluconeogenesis, a large portion of serum nonesterified fatty acids is directed to ketone body synthesis in the liver. Thus, the clinicopathologic characterization of ketosis includes high serum concentrations of nonesterified fatty acids and ketone bodies and low con- centrations of glucose. Said serum ketone bodies are acetone, acetoacetate, and β- hy droxybutyrate . Ketosis occurring closer to peak milk production, which usually occurs at 4-6 week postpartum, may also be associated with underfed cattle experiencing a metabolic shortage of gluconeogenic precursors.

All dairy cows in early lactation, particularly during first 6 weeks are at risk of ketosis. Cows with excessive adipose stores (body condition score >3.75 out of 5.0) at calving are at increased risk of ketosis, compared with those with lower body condition scores. Lactating cows with hyperketonemia (serum β- hydroxybutyrate concentrations >12 mg/dL) are at increased risk of developing clinical ketosis. Positive milk tests for acetoacetate and/or acetone usually indicate clinical ketosis. Ketosis may also lead to acidosis in some cases.

The treatment of ketosis is aimed at reestablishing normoglycemia and reducing serum ketone body concentrations. Bolus glucose therapy generally results in rapid recovery, especially in cases occurring near peak lactation. However, the effect frequently is transient and relapses are common. Administration of glucocorticoids generally results in a more sustained response. Propylene glycol is often used in the treatment of ketosis and it acts as a glucose precursor and may be effective as ketosis therapy, especially in mild cases or in combination with other therapies. Overdosing propylene glycol leads to CNS depression.

Insulin is used in the treatment of ketosis cases occurring within the first weeks after calving. Insulin suppresses both adipose mobilization and ketogenesis, but should be given in combination with glucose or glucocorticoids to prevent hypo- glycemia.

Prevention of ketosis is typically carried out via nutritional management. The body condition of cows should be managed in late lactation, when cows frequently become too fat. The dry period is generally too late to reduce body condi- tion score. A critical area in ketosis prevention is maintaining and promoting feed intake. Cows tend to reduce feed consumption in the last 3 wk of gestation and the feed reduction should be minimized with nutritional management. It is essential to monitor feed intake and adjust rations to maximize dry matter and energy consumption in late gestation. After calving, diets should promote rapid and sustained increases in feed and energy consumption. Similar metabolic disorders are en- countered with ewes and cutters.

Metabolic disorders are encountered in bovine animals, sheep, poultry, pets and hoofed animals, particularly under situations causing elevated stress to the animal or when there appear changes or interruption of feeding patterns.

Examples of stress situations relating to horses are horseshows and competitions like show-jumping, horse racing and other demanding sporting events. Also situations when animals are housed and fed only at certain times of day, or natural feeding patterns are disrupted, or exercising patterns are disrupted or continuous access to forage is restricted, the animal may become stressed and metabolic disorders occur.

It has recently been demonstrated that particularly sporting and racing horses may, as a result of increased stress, develop various gastric problems, which may even eventually lead to gastric ulcers. Several approaches have been suggested to alleviate this problem. Pharmaceutical substances typically used in the treatment of humans have now been suggested for horses and also complementary horse food products are available.

Colic in horses is defined as abdominal pain, but it is a clinical sign rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. The most common forms of colic are gastrointestinal in nature and are most often related to colonic disturbance. There are a variety of different causes of colic, some of which can prove fatal without surgical intervention. Colic surgery is usually an expensive procedure as it is major abdominal surgery, often with intensive aftercare. Among domesticated horses, colic is a major cause of premature death.

WO 03/005834 discloses a high-fat animal feed in the form of pellets. It was no- ticed that hemicellulose and particularly corn hull hemicellulose possesses superior properties as a binder in high- fat animal feeds in amounts of 0. - 10 % by weight, providing sufficient interparticle cohesion. Said hemicellulose was obtained as a liquid fraction resulting from alkaline cooking of a hemicellulose- containing agricultural residue, such as corn hull residue. Said feed contains also fat, a solid nutritive source, a protein source and a fiber source.

GB 2 406 516 presents a complementary feed composition particularly for horses for the treatment of gastric ulcers. Said composition comprises a fiber source, (cut grass or refined source of hemicellulose, etc.), a mucilage source (mucopolysac- charides, full fat linseed or the like providing a mucus when dispersed in water), a fat source providing fat with high triglyceride content and low free fatty acid content (linseed oil, rapeseed oil, etc.) and additionally optional phospholipid sources, antioxidants and protein sources. The composition is claimed to maintain normal gastric function in horses when feeding the composition between the meals. It requires high chewing rate, which in turn generates a good volume of saliva by the horse, it has a long stomach retention rate and provides additional buffering in the stomach.

Wood molasses have been suggested to be included in ruminant diet. Virtanen, A. L, New Views in Cattle Feeding, Agrochimica XI n. 4-5, Giugno-Agosto (1967) carried out experiments with milking cows on a feed comprising hemicellulose powder obtained from wood, in combination with urea as the sole nitrogen source, added to barley, oats, sugar beet pulp, fiber and oat straw. As a result of this diet the milk production of the cows was increased and the sugar content of the milk was elevated. Wood molasses is obtainable from wood species, particularly from hardwood, such as birch, aspen and beech, but also from softwood. Wood molasses is often described as aqueous soluble hemicellulose extract of wood. Wood molasses is typically in the form of syrup or powder and it can be produced from wood at ele- vated temperature and pressure. It typically contains about 50-60 % by weight of hemicellulose based on the solid content, comprising nearly equal distribution of 5-carbon and 6-carbon sugars, around half of them being as simple sugars. Simple sugars (small molecular weight carbohydrates) are not desired energy sources in animal feeds because they cause a rapid peak in the blood sugar level and they are metabolized to undesired fat, increasing adipose stores. Wood molasses may also contain undesired impurities such as furfural, depending on the manufacturing method.

Hemicellulose may also be obtained from other plant-based materials, such as various parts of grain, bagasse, coconut shells, cottonseed skins, corn etc.

Based on the above it can be seen that there exists an evident need for new animal feeds and particularly for animal feed extenders, supplements and toppings for ruminants and monogastric animals, useful in the prevention and treatment of metabolic disorders in an animal and /or when the animal requires high-energy feed. There is also a need for new energy sources for animal feeds for ruminants and monogastric animals.

Object of Invention

An object of the invention is an animal feed, particularly an animal feed extender, animal feed supplement and animal feed topping for ruminants and monogastric animals. A further object of the invention is an animal feed, particularly an animal feed extender, animal feed supplement and animal feed topping for ruminants and monogastric animals, in the need of high-energy nutrients.

A still further object of the invention is an animal feed, particularly an animal feed extender, animal feed supplement and animal feed topping for ruminants and monogastric animals, for the treatment and prevention of metabolic disorders in the animal.

A further object of the invention is a method for the manufacture of an animal feed composition, particularly an animal feed extender, animal feed supplement and animal feed topping for ruminants and monogastric animals.

A still further object of the invention is the use of xylan as a component in animal feed, and as an animal feed extender, animal feed supplement and animal feed topping for ruminants and monogastric animals.

A still further object of the invention is the use of galactoglucomannan as a component in animal feed, and as an animal feed extender, animal feed supplement and animal feed topping for ruminants and monogastric animals.

A still further object of the invention is the use of mixtures of xylan and galactoglucomannan as components in animal feeds, and as animal feed extenders, animal feed supplements and animal feed toppings for ruminants and monogastric animals.

Characteristic features of the invention are provided in the claims. Definitions

Here xylan is understood to mean a group of polymeric pentoses belonging to heteropolysaccharides, forming constituents in plant cell walls. All xylan fractions and subgroups, for example arabinoglucuronoxylan and glucuronoxylan are understood to belong to the group of xylans.

Here galactoglucomannan is understood to mean a group of polymeric hexoses belonging to heteropolysaccharides, forming constituents in plant cell walls. All galactoglucomannan fractions and subgroups are understood to belong to the group of galactoglucomannans.

Here animal feed is understood to mean industrial animal feed.

The term "feed" or "animal feed" as used in the description and claims refers to the total feed composition of an animal diet or to a part of it. Thus, unless specifically stated, the term "feed" or "animal feed" should be taken to mean to include supplemental feed, premixes, water or other liquids for drinking etc. The feed may comprise different active ingredients.

Summary of Invention

The present invention is directed to animal feeds, and particularly to animal feed extenders, animal feed supplements and animal feed toppings for ruminants and monogastric animals, said animal feeds, animal feed extenders, animal feed supplements and animal feed toppings comprising xylan or galactoglucomannan or mixtures thereof.

The invention is also directed to the use of xylan or galactoglucomannan or mixtures thereof as components in animal feeds and in animal feed compositions, particularly as animal feed extenders, animal feed supplements and animal feed toppings, useful in the treatment and prevention of metabolic disorders in an animal and as high-energy nutrients for ruminants and monogastric animals. Examples of ruminants and monogastric animals are beef, dairy cattle, musks, deers, reindeers, sheep, pigs, poultry, pets and hoofed animals like horses and po- nies etc.

Suitably the animal feed or the animal feed composition comprises 0.005 - 40 % by weight of xylan or galactoglucomannan or a mixture thereof.

Xylan and galactoglucomannan are polymers, which belong to the group of polymeric heteropolysaccharides obtainable from plants including wood species. Preferably xylan and galactoglucomannan originate from woodspecies including hardwood and softwood species. Suitably xylan and galactoglucomannan can be obtained from paper and pulp process side-streams such as side-streams from hardwood pulp or softwood pulp processes, or mixtures thereof.

Figures

Figure 1 shows cumulative gas production with xylan and galactoglucomannan during 9 hours rumen fermentation.

Figure 2 shows gas production dynamics with xylan and galactoglucomannan during 0-3 hours rumen fermentation.

Figure 3 shows gas production dynamics with xylan and galactoglucomannan during 3-6 hours rumen fermentation. Figure 4 shows gas production dynamics with xylan and galactoglucomannan during 6-9 hours rumen fermentation.

Figure 5 shows formation of short chain fatty acids with xylan and galactoglucomannan.

Figure 6 shows formation of volatile fatty acids with xylan and galactoglucoman- nan.

Figure 7 shows formation of lactic acid with xylan and galactoglucomannan. Figure 8 shows the effect of xylan and galactoglucomannan on rumen pH. Figure 9 shows formation of propionic acids with xylan and galactoglucomannan. Figure 10 shows formation of acetic acid with xylan and galactoglucomannan. Figure 11 shows formation of butyric acid with xylan and galactoglucomannan. Figure 12 shows the effect of xylan and galactoglucomannan on rumen microbial growth.

Figure 13 shows the effect of xylan and galactoglucomannan on digested neutral detergent fibre.

Detailed Description of Invention

It was surprisingly found that certain polymeric pentoses and hexoses, namely xylan and galactoglucomannan are particularly suitable as components in animal feeds and animal feed compositions, as animal feed extenders and supplements and toppings or components thereof, for ruminants and monogastric animals. Said xylan and galactoglucomannan preferably originate from woodspecies. Particularly ruminants and monogastric animals, such as hoofed animals, goats and sheep are adapted to digest highly fibrous plant material as energy and protein source.

Xylan or galactoglucomannan or mixtures thereof may be added to animal daily feed as such or in liquid form or in powder form, or they may be included in an animal feed extender or supplement or topping in an amount of 0.005 - 40 % by weight, optionally with suitable carriers and additives known in the art, and also used as components in animal feeds and animal feed compositions in an amount of 0.005 - 40 % by weight. These polymeric substances xylan and galactoglucomannan are particularly suitable as components in the daily nourishment for ruminants and monogastric animals, such as beef, dairy cattle, musks, deers, reindeers, sheep, goats and hoofed animals like horses and ponies, and also in the daily nourishment for poultry, pigs and pets. Xylan and galactoglucomannan are carbohydrate nutrients having high purity level and high energy content. Because they are polymeric compounds, they are metabolized more slowly, thus providing a more stable energy source for a longer period of time. They can be used for replacing grain based nutrients or feed partly or in some cases even completely and thus the carbohydrates of grain are replaced with xylan and/or galactoglucomannan.

Xylans and galactoglucomannans are heteropolysaccharides, which are naturally occurring carbohydrate-based polymers belonging to the hemicelluloses. The main building units of xylan and galactoglucomannan are pentoses and hexoses, but additionally they may contain other moieties. The weight average molecular weight Mw of xylan varies between 5000 and 100 000 g/mol and the weight average molecular weight Mw of galactoglucomannan varies between 5000 and 100 000 g/mol, when determined using SEC Size -Exclusion Chromatogaphy method, well known in the art for determining molecular weights of polymers.

Xylan originating from wood species comprises glucurono moieties in its structure. Arabinoglucuronoxylan and glucuronoxylan are examples of xylanes obtainable from woodspecies. Xylan has in its structure a linear backbone consisting of (l→4)-linked β-D-xylopyranosyl units. Arabinoglucuronoxylan is composed of an essentially linear framework of (l→4)-linked β-D-xylopyranosyl units containing branches of both (l→2)-linked pyranoid 4-O-methyl-α-D-glucuronic acid and (l→3)-linked α-L-arabinofuranose. Glucuronoxylan has the same framework as the above-described arabinoglucuronoxylan but it contains fewer uronic acid substituents.

Galactoglucomannan is built up of mainly linear backbone of (l→4)-linked β-D- glucopyranoses and β-D-mannopyranosyl units. They are partly acetylated at C2- OH and C3-OH and substituted by (l→6)-linked α-D-galactopyranosyl units. Galactoglucomannans can be divided into galactose-rich galactoglucomannan and glucomannan with lower galactose content. Hardwood contains typically glucuronoxylan and glucomannan, softwood contain typically galactoglucomannans and arabinoglucuronoxylan.

Glucomannan obtainable from hardwood has the same linear framework as soft- wood glucomannan, except that it is unsubstituted, not acetylated and it has a higher glucose to mannose ratio.

Xylans and galactoglucomannans obtainable from wood species differ with respect to the composition of various sugar units, molecular mass, degree of polym- erization and branching from hemicelluloses obtainable from annual plants and cereals. Thus also the physicochemical characteristics differ.

Xylan and galactoglucomannan can be obtained from plant-based materials using any methods available in the art. Particularly paper and pulp process side-streams contain hemicellulose fractions, which can further be processed to xylan and galactoglucomannan. Hardwood and softwood pulps contain significant amounts hemicelluloses, however, hardwood and softwood pulps differ in both the amount and the chemical composition of the hemicelluloses, which they contain. In hardwoods, the principal hemicellulose is glucuronoxylan while softwoods contain chiefly galactoglucomannan.

There are three general types of chemical pulps known in the art: (1) Soda pulp produced by digesting wood chips at elevated temperatures with aqueous sodium hydroxide. (2) Kraft pulp typically produced by digesting wood chips at temperatures above about 120° C with a solution of sodium hydroxide and sodium sulfide. (3) Sulfite pulp produced by digesting wood with sulfur dioxide and a base.

Bleaching of pulp usually involves treatment with oxidizing agents, such as oxy- gen, peroxide, chlorine, or chlorine dioxide. Classically, the pulp is treated with chlorine, then extracted with caustic, and finally treated with hypochlorite. Alkaline extraction with cold caustic removes xylan from pulp in an efficient way.

It is generally known that hemicelluloses can be dissolved at alkaline conditions in aqueous solutions. FI 55516 discloses a method where hardwood pulp is extracted with an aqueous solution of NaOH to yield an extract containing high amounts of xylan, followed by precipitation of the hemicelluloses with carbon dioxide.

US 4,181,796 provides a process where vegetable raw material, such as hardwood, straw, bagasse, grain husk, corn-cob residues, or maize straw is treated with saturated steam at 160 - 23O⁰C temperature, whereby the vegetable raw material is disintegrated and an aqueous solution containing xylans, among other compounds, is obtained. Xylans can be separated using strongly basic ion ex- change resins in the OH form.

Also methods involving oxidative or reductive steps, complex forming and membrane separation techniques for producing hemicelluloses are known in the art.

Xylan and galactoglucomannan are also particularly suitable for the prevention and treatment of ketosis in ruminants like bovine animals, sheep and goats. When added to the daily nourishment of an animal, xylan or galactoglucomannan or mixtures thereof provide a high-energy source, which is metabolized more slowly than for example carbohydrates contained in grain, additionally the fermentation in the rumen is enhanced and modified, and further the amounts of the desired short chain fatty acids from fermentation in the rumen are increased.

Xylans obtainable from wood species contain glucuronic groups, which are digested in a different way in animals when compared with xylans obtainable for example from corn or annual plants, which contain arabinose groups but no glucuronic groups. Xylan containing arabinose groups requires a broader range of enzymes as well as a broader range of microbes for digesting it. Additionally the metabolic route of arabinose is different and there are fewer microbes able to utilize arabinose sugars. Thus xylans obtainable from wood species, particularly glu- crunoxylan, are more easily digested by animals and they are also utilized more effectively by the microbes in the digestive tract of the animal.

In monogastric animals, xylan and galactoglucomannan, particularly xylan is not decomposed in the small intestine but in the colon, thus making these substances particularly suitable for the prevention of metabolic disorders, such as horse colic. Further, as the fermentation products of xylan, such as butyrates are absorbed in the colon of monogastric animals, 20 % or even more of animal's daily energy may originate from xylan. Xylan and galactoglucomannan also modify and enhance the fermentation in the intestines of a monogastric animal. Further, very low amounts of lactic acid are obtained as fermentation products from xylan.

0.001 - 40 %, preferably 1 - 20 % by weight of xylan and/or galactoglucomannan may be added to the daily nourishment of an animal, as such, as a water solution, as a topping or as a component in a feed composition, feed extender or feed supplement.

When administered to ruminants, xylan and galactoglucomannan improve almost all rumen performance parameters. They provide an alternative and extra energy source for an animal and particularly for rumen digestion in ruminants.

Xylan and galactoglucomannan accelerate the microbial activity in the rumen and enhance the protein and energy uptake, resulting in increased wellbeing, milk production and growth of the animal. Xylan and galactoglucomannan increase gas production in rumen, indicating improved ruminal digestion, which typically correlates with better animal productivity and health status. Xylan and galactoglu- comannan improve rumen energy balance by stimulating short chain fatty acid production, particularly the production of acetic acid. Xylan and galactogluco- mannan both increase biomass synthesis, galactoglucomannan more significantly with higher dosages. Ruminants have the ability to break down rumen microbes having high protein content and they use the released amino acids for their own protein synthesis. Thus, increased rumen microbial growth correlates with in- creased animal productivity. Xylan and galactoglucomannan enhance neutral fiber digestion digestion rate, which increase animal performance and milk production significantly.

The feed digestion process in ruminants is initiated at a special digestion com- partment, called rumen. The rumen is a sophisticated microbial fermentor where a vast amount of different microbes degrade plant material and convert it to more convenient form of energy and protein. Therefore, the rumen microbiological activity has primary importance to determine the ruminant performance and productivity.

A rumen simulation method was developed, measuring accurately the most important rumen performance parameters. The rumen performance parameters measured in the rumen simulation system are as follows:

• Gas production kinetics, which is a general indicator of the rate and extent of dry matter digestion by rumen bacteria. It is normally interpreted so that faster gas production kinetics and higher total volume mean improved ruminal digestion. The higher rumen digestion typically correlates with better animal productivity and health status. • Short chain fatty acids (SCFAs) concentration, said acids being the major end metabolites produced by rumen bacteria. SCFAs are absorbed through the ruminal epithelial and used as a major energy sources by the animal. Normally higher total SFCA production implies better animal energy balance and performance. • SCFA profiles and their proportions in percentages. SCFAs include many chemical entities, such as acetate, propionate, butyrate, valeriate, lactate esters of fatty acids and their isomers. These entities have different roles in the animal. For example, lactates have a tendency to lower rumen pH and cause acidosis that lowers animal productivity and can cause permanent damage to animal rumen epithelium. In con- trast, propionate typically has a positive effect on animal performance, milk production and is able to prevent ketosis, which is a serious malfunction encountering high performance animal. High butyrate and acetate production have tendency to increase milk fat content.

• Growth of microbial density (i.e. microbial biomass) is an indicator parameter for animal protein supply, because the rumen bacteria form a major protein source for ruminants. Typically higher protein production correlates with higher milk volume and milk protein content.

• Neutral detergent fibre (NDF) (mainly hemicellulose) digestion rate. NDF is the main energy and nutrient source for rumen bacteria, and it is also the cheapest nutrient component in the ruminant feed. Therefore, the high NDF digestion rate is desirable characteristic in the ruminant feeds.

It was revealed that xylan and galactoglucomannan provide a source of carbohy- drates, which yield a more stable, slower and linear response than many other polymeric hemicellulose compounds.

According to the invention xylan or galactoglucomannan or mixtures thereof can be used as feed supplements for administering to ruminants and monogastric ani- mals on daily basis when needed or continuously. Xylan and galactoglucomannan have a mild taste and thus no additives are necessary for improving palatability. If desired, xylan and/or galactoglucomannan may be formulated as liquids, suitably as water solutions, concentrates, powders, toppings, animal feeds and animal feed supplements and compositions with suitable carriers and additives well known in the art and they may be used in animal feeds, animal feed supplements and animal feed extenders. The invention is further illustrated with the following example, which however are not intended to limit the scope the invention.

Example 1. Rumen simulation test

Feed

Feed for rumen simulation was used as Ig (DM)/vessel application level, and it was composed of 50% of commercial compound cattle feed and 50% of grass silage. The grass silage was sampled and immediately after sampling the grass silage was anaerobically packed into the glass containers and stored at +4°C to prevent any aerobic spoiling processes. Both feed components were individually weighed in each simulation vessel.

Test products The substances were tested in two dose levels (level A: simulation doses, level B: real feeding doses), which are summarized in following Table 1, providing a list of treatments, dose levels and their estimated daily dose rate in real feeding application. The estimated daily dose is based on the assumption that average cow consumes 10kg of dry matter per day. Xylan was glucuronoxylan obtained from birch and galactoglucomannan was obtained from spruce.

Table 1.

Simulation protocol Feed components and test products were weighted in serum bottles, and then flushed with CO₂, which had been passed through a hot copper catalyst for ultimate O₂ removal, and sealed with thick butyl rubber stoppers. Anaerobic and re- duced buffer solution and fresh rumen fluid (to the final dilution of 1 :40) were added in the serum bottles using strictly anaerobic techniques. Gas production was measured after 3, 6 and 9 hours of simulation at 37 ⁰C.

After 9 hours of incubation the simulation vessels were sampled for the analysis of pH, short chain fatty acids (SCFAs) and count of total bacteria.

Total bacteria were enumerated by flow cytometry using staining with a DNA specific dye, Syto 24, and settings adjusted to counting of bacteria. SCFAs were analyzed by gas chromatography using a packed column for the analysis of free acids. Acetic acid, propionic acid, butyric acid, iso-butyric acid, 2-methyl-butyric acid, valeric acid, iso-valeric acid and lactic acid were analysed. pH was measured by specific electrodes.

Neutral detergent fibre (NDF) analysis

The rate of fibre digestion was performed by measuring the remaining neutral detergent fibre (NDF) after 24 hour fermentation. For the determination of NDF, extraction buffer was added in the simulation bottles, the bottles were incubated at 100 ⁰C, sieved through a 100 μm sieve, rinsed with boiling water and then with acetone. The sieves were thereafter dried and the amount of dry material weighed. The remaining dry material contains the undigested cellulose, hemicellulose and lignin fractions of the feed.

Statistical analysis Three test compound levels were chosen to effectively capture dose effects on rumen fermentation. The a priori assumption was linear dose dependence in the responses of rumen fermentation parameters to the test compounds. To test this assumption, linear dose models were fitted for all test compounds for each rumen fermentation parameter. As with some parameters the test compounds gave simi- lar responses with all levels tested, step models indicating a situation in which all levels of test compound give equal response were also fitted. Furthermore, Dun- nett's test was used to detect those test compound levels for which the response differed significantly from that in the control treatment.

Results Figure 1 shows that both xylan and galactoglucomannan increase the overall gas production during the rumen fermentation and particularly galactoglucomannan increases dose dependently the overall gas production during the 9 hours rumen fermentation. Furthermore, the gas production dynamics, presented in figures 2-4, indicate that both xylan and galactoglucomannan increased gas production and particularly galactoglucomannan was able to increase gas production throughout the whole 9 hours rumen simulation period. This shows that both xylan and galactoglucomannan, particularly galactoglucomannan, are good substrates for rumen microbes and they are largely consumed during the microbial fermentation process, thus being good energy sources to ruminant feeds. Increased gas production indicates improved ruminal digestion. The higher rumen digestion typically correlates with better animal productivity and health status.

Xylan and galactoglucomannan improve rumen energy balance by stimulating short chain fatty acid production. Short chain fatty acids (SCFAs) are the main energy source for ruminant. The SCFAs are synthesised by rumen microbes and absorbed through rumen epithelium to bloodstream, and thereafter converted to energy by various metabolic processes. Therefore, the elevated SCFA concentrations shown in figure 5 indicate that xylan and galactoglucomannan are able to improve ruminant performance by increasing their energy supply. Typically higher SCFA production rate correlates positively with increased rumen gas production kinetics, which is the case with galactoglucomannan but not with xylan. It is likely the high pentose sugar content of xylan directs rumen metabolism to the routes that produce less gas than what is evolved from the hexose sugars of the galactoglucomannan. The SCFAs are composed of two different components, volatile fatty acids (VFAs) and lactic acid. VFAs are stable end-products of rumen fermentation and therefore readily available for the host animal. However, lactic acid is a transient intermediate of rumen fermentation. Its production is typically increased with high-energy feeds and its accumulation may lead to a condition called rumen acidosis. Rumen acidosis causes serious rumen malfunction, decrease of animal performance and even permanent damages to rumen epithelium. Figures 6 and 7 point out that xylan and galactoglucomannan mainly increase the rumen VFAs concentrations and not lactic acid concentrations. Similarly, xylan and galactoglu- comannan have only minor effects on rumen pH, as can be seen in Figure 8, which means that their rumen application does not create immediate danger of rumen acidosis.

Xylan and galactoglucomannan slightly decrease propionic acid production as can be seen in Figure 9, as well butyric acid production, as can be seen in Figure 11.

Xylan and galactoglucomannan mainly increase rumen acetate production, as can be seen in Figure 10. Anaerobic carbohydrate metabolism typically yields two stable main metabolites, acetate and butyrate. Acetate is readily available for use by the host animal for energy production, and butyrate has tendency to increase milk fat content. Therefore, the dose dependent increase of acetate by xylan and galactoglucomannan demonstrates their suitability as new feed energy sources.

Xylan and galactoglucomannan both increase biomass synthesis, galactoglucomannan more significantly with higher dosages. Rumen microbes have high pro- tein content and therefore ruminants have developed ability to breakdown rumen microbes and use released amino acids for their own protein synthesis. Therefore, increased rumen microbial growth correlates with higher animal productivity and increased milk protein concentration. Figure 12 indicates that particularly higher dosages of galactoglucomannan increase rumen microbial growth. Xylan and galactoglucomannan enhanced neutral fiber digestion (NDF) digestion rate. Animal performance and milk production correlate strongly with rumen NDF digestion rate. The higher the NDF digestion rate - the more milk is produced. Figure 13 shows that both xylan and galactoglucomannan achieve significantly increased NDF digestion rates.

Claims

1. An animal feed composition, characterised in that the animal feed composition is an animal feed topping, animal feed extender or animal feed supplement and the animal feed composition comprises xylan or galac- toglucomannan or mixtures thereof, obtainable from wood species.

2. The animal feed compositions according to claim 1, characterised in that xylan is selected from arabinoglucuronoxylan and glucuronoxylan.

3. The animal feed compositions according to claim 1 or 2, characterised in that the animal feed composition contains 0.001 - 40 % by weight of xylan or galactoglucomannan or a mixture thereof.

4. The animal feed composition according to any one of claims 1 - 3, characterised in that the weight average molecular weight Mw of xylan varies between 5000 and 100 000 g/mol.

5. The animal feed composition according to any one of claims 1 - 3, charac- terised in that the weight average molecular weight Mw of galactoglucomannan varies between 5000 and 100 000 g/mol.

6. The animal feed composition according to any one of claims 1 - 5, characterised in that the animal is a ruminant or a monogastric animal.

7. Use of xylan or galactoglucomannan or mixtures thereof, obtainable from wood species, in animal feed compositions selected from animal feed supplements, animal feed extenders and animal feed topping or as components therein.

8. The use according to claim 7, characterised in that xylan is selected from arabinoglucuronoxylan and glucuronoxylan.

9. The use according to claim 7 or 8, characterised in that xylan or galac- toglucomannan or mixtures thereof is used in an amount of 0.001 - 40 % by weight.

10. The use according to any one of claims 7 - 9, characterised in that the weight average molecular weight Mw of xylan varies between 5000 and 100 000 g/mol.

11. The use according to any one of claims 7 - 9, characterised in that the weight average molecular weight Mw of galactoglucomannan varies between 5000 and 100 000 g/mol.

12. The use according to any one of claims 7 - 11, characterised in that that the animal is a ruminant or a monogastric animal.