General disclosure

The present invention concerns a feed composition rich in starch for ruminants , the feed composition comprising amy- lose lipid complexes for reducing the rate of degradation of the starch in such complexes in the rumen of the animals . Additionally the present invention concerns a post- treatment process for improving commercially available feeds for ruminants increasing the contents of amylose lipid complexes in such feed as well as a process for producing the starch-rich and fat-containing feed according to the invention . Also, the present invention concerns the use of amylose lipid complexes in feed for ruminants .

Background of the invention

Ruminants , e . g . normal as well as high-yielding cows , are normally given a feed that is rich in starch because this represents a diet that the digestive system of the animal is capable of digesting and additionally this is a feed which has a high energy concentration, is inexpensive and which is durable with respect to storage . Starch will partly be broken down by the micro-flora in the rumen, and partially by digestive enzymes in the small intestine .

When commercial starch-rich feeds are given to ruminants , however, the starch content in the feed is broken down in the rumen relatively quickly, creating an unfavourable rumen environment characterized by a high proportion of propionic acid formed by bacterial digestion of starch . This will affect the pH in the rumen to creating a more acidic environment leading to a possible un-healthy condition and thus reduced performance . This altered environment in the rumen will also affect the microbial fauna in a deleterious - way creating an opportunity for infectious and

competitive microorganisms to establish colonies in the rumen competing with the normal microbial fauna . An altered micro-flora may also affect the digestibility of other components negatively. Also, it is energetically more effec- 5 tive to digest starch as glucose in the small intestine than to convert starch into short chain fatty acids in the rumen . This also favours methods to protect starch from degradation in the rumen . These problems are pronounced in e . g . high-yielding dairy cows where an optimal digestibil- o ity combined with a healthy rumen environment to avoid diseases is sought for .

Consequently there exists a need within the farming and ruminant-raising community to obtain a starch-rich feed that reduces the digestive speed of the starch in the rumen, and s preferably alters the site of digestion of a part of the starch from the rumen to the small intestine .

Obviously, a part of the starch should be (and is) digested in the rumen simulating a normal rate of digestion of the starch in the feed.

o Formation of amylose/lipid complexes is known to occur during moist conditions when a mixture of starch and fats is heated (Bhatnagar and Hanna, 1994 , Cereal Chemistry 71 , 582 ; Karkalas et al . , 1995, Carbohydrate Research 268 , 233 ; Boltz and Thompson, 1999, Cereal Chemistry 76, 204 ; 5 Tufvesson and Eliasson, 2000 , Carbohydrate Polymers 43 , 359 ; Kaur and Singh, 2000 , Food Chemistry 71 , 511 ; Tufvesson et al . , 2003, Starch 55, 61; Tufveson et al . 2003 , Starch 55 , 138 ) . The complex occurs due to non-cova- lent forces between the amylose helix and the non-polar end 0 of fatty acids . This complex is resistant to enzymatic digestion of the starch (Larsson and Miezis , 1979, Starch 31 , 301 ; Cui and Oates , 1999, Food Chemistry 65 , 417 ; Tufvesson et al . , 2001, Lebensmittelwiessenschaft und Technologie 34 , 131 ) .

Commercial feed for ruminants includes about 40% (w/w) starch with a normal amylose content (20-30% ) . According to prior art such feed may be added up to 4% (w/w) fat, usually in the form of vegetable oils or animal fats from the rendering industries . Such added fats have, however, not had any specified composition and no care has been taken for ameliorating the undesirable effects of increased breakdown of starch in the rumen . Consequently this has not resulted in any significant reduction of the breakdown of starch in the rumen, and with the consecutive formation of the acid rumen environment and detrimental consequences as disclosed supra .

As a background for the present invention it is not based on the mechanism with formation of amylose-lipid complexes and their effect on the digestibility not being known, but rather on a unique and formerly not disclosed use of feed- technological processes for forming these amylose-lipid complexes coupled up to a previously not disclosed effect in the rumen of ruminants .

Formerly amylose-lipid complexes are known that are formed through a boiling process where there is an abundance of water . The feed-technological process according to the present invention differs significantly from the formerly known process for creating amylose-lipid complexes in the circumstance that in the present process it is not added more than 20 to 60 g water per kg feed and the temperature does not normally exceed 90 ° C . Additionally, the treatment time is less than 5 minutes . Consequently it is not obvious that that the formation of amylose-lipid complexes will be similar to the prior art under these conditions .

The specific ingredients being used in the feed and process according to the present invention also differ from the ingredients normally being used in feed for household animals according to the prior art . It is thus surprising

that amylose-lipid complexes are indeed formed under the conditions used according to the present invention .

Further considerations concerning the present invention is that formerly it was unknown how the degradation of starch in the rumen of ruminants is affected by amylose-lipid complexes . In tests having been performed with rumen- fistulated animals it has been established that the amylose-lipid complexes according to the present invention formed during the process according to the present invention reduce the degradation of starch in the rumen .

The present invention consequently also includes the realization of the existence of these circumstances in amylose-lipid complex formation to obtain a specific feed- processing method with specific ingredients and the unique effect this has on the nutritional value of the feed for ruminants .

In connection with the present invention the suitable content of amylose in the starch of the feed according to the invention will lie within the interval 20 up to 70% (w/w) . The realization that such amylose/fat complexes may be used for regulating the digestibility, and thereby the well-being of the ruminants through the ingestion of such complexes, has not previously existed within the professional community.

Additionally, the formation of such complexes between amylose and fat is, however, not any guarantee for them to be suitable for feed for ruminants , since they might present any number of unfavourable features , e . g . too low digestibility, unfavourable side effects (toxicity, unfavourable on account of disease-promoting alteration of the microbial environment in the digestive tract, etc . ) , non-palatability of the feed for the ruminants , alteration of the storage properties of the feed, formation of rancid by-products , etc ..

Surprisingly and unexpectedly it has , however, been found that the addition of fats that will form such complexes between the starch and fat as indicated supra to ruminant feed rich in starch and amylose, will produce a feed with an altered and favourable digestion rate reducing or obviating the above indicated disadvantages of normal and commercially available starch-rich feed.

General disclosure of the invention

The present invention is thus in a first aspect concerned with altering the availability of the starch which is present in feed for ruminants by adding lipids , preferably in the form of fat, to the feed. More specifically the present invention is concerned with altering feed for ruminants with a high content of starch by adding lipids , pref- erably with a high content of stearic, palmitic and/or myristic acid to the feed. The fats may be present in the form of each lipid type alone or they may be present in the form of any combination of the relevant fats . Other fat types than the ones indicated supra may also be used as long as they form the indicated amylose/fat complexes .

Tests for determining which fats that have this capability are available within the art (see the references mentioned supra) and will not represent any undue burden of experimentation for the practitioner . The addition of fats to the starch reduces the bioavailability of the starch for the ruminal microflora . The amount of fat added to the starch will be dependent on the amount of amylose in the starch . The ratio between amylose and fat (amylose : fat) in the feed according to the invention will in some embodi- ments of the invention be in the order 2 : 0 , 5 - 0 , 5 : 2 , and is preferably around 1 : 0 , 5 , although such intervals are not necessarily imperative . The basis for improving the starch-rich feed by adding fats lie primarily in adding fats that have the capability of forming amylose/fat com- plexes according to the invention, although the intervals indicated supra in relation the formation of amylose/fat

complexes may in general be used, and is especially used in connection with the special lipids that are mentioned specifically.

The starch present in the feed according to the invention is preferably, though not necessarily, a high-amylose starch (i . e . with an amylose content of up to 70% (w/w) ) , though also starches not as rich in amylose may be used . In the present context the expression "starch" is meant to include different starch derivatives or starch types as well , e . g . hydroxyethylated starch or hydroxypropylated starch, starch that has been subj ected to oxidation, acid treatment or enzymatic treatment, starch derived from bio- technologically modified starch sources (corn, potato, rice etc . ) .

The present invention is furthermore in a second aspect concerned with providing a feed containing starch and a fat source . The starch source in the feed according to the present invention is primarily cereals and/or a variety of cereals with a normal to high amylose content, and the fat source in the feed according to the present invention preferably contains a high level of stearic, palmitic and/or myristic acid . Examples of suitable cereals to be used in the present invention include barley and oats . The fat source in the feed according to the present invention in- eludes lipids such as monoglycerides, diglycerides, free fatty acids , emulgating lipidous substances such as lechitins , etc .

A third aspect of the present invention is a process for altering the digestibility of known feed for ruminants with a high content of starch, by adding to such feed a source for lipids, preferably fats and more preferably the fats mentioned supra .

A fourth aspect of the present invention is the use of fats in feed for ruminants for altering the digestibility of the

starch/amylose in the feed. The fats to be used according to the present invention include the fats and lipids mentioned supra . The fats should not be unsaturated fats , and fats with a carbon chain length of Cio- ₃₅ , more preferred Ci4_26/- e . g . palmitic, stearic or myristic acid may be used.

Embodiments of the invention

According to the first aspect of the invention mentioned supra, the invention concerns a method for altering the bioavailability of starch for the amylose enzyme by non-co- valently associating the amylose of the starch with fats/lipids . This is conveniently done by simply adding the fats/lipids to the feed for incorporation . Any close association between the fats/lipids and starch/amylose will form the relevant non-covalent complexes . Any fat source may be used for producing the relevant complexes , but it is preferred to use the above mentioned lipids since they have a favourable complex-forming rate of formation . However, the rate of formation is not a critical feature of the present invention . Fats which rapidly form amylose/lipid com- plexes, e . g . the fats mentioned are added to ordinary ruminant diets at inclusion levels from 4% and normally from 4% and up to 10% (although this upper level is not critical ) , e . g . 5 - 9% (w/w) . The fat source may include free fatty acids , monoglycerides , or emulgating triglycerides like lechitins .

If myristic, palmitic and/or stearic acid are used, the total level of these fats should be higher than 300 g/kg ( 30% w/w) in the fat source . This fat is mechanically mixed with the feed, or in the event of a feed being produced from the basic feed components , with the other common ingredients of the feed . This addition is preferably followed by the addition of 20 to 60 g/kg water in the form of steam to increase the temperature of the inclusion process and thereby increase the amylose lipid complex formation rate in the feed. In this process the feed will be heated

to above 70 ⁰ C in a conditioner, optionally followed by further heating in a pellet press to a maximum temperature of 9O ⁰ C .

Alternatively, the conditioning process may be followed by an expander process where the temperature is increased under pressure to a maximum of HO ⁰ C . The pressure to be used in such a process is normally within the range 20-40 bar .

Subsequently to the conditioning/expander process , the feed will be pelleted at the increased temperature if necessary. The pelleted diets will be cooled to room-temperature immediately after pelleting .

The above given disclosure of the addition of fats to the ruminant feed according to the present invention is rele- vant for both including fats to commercially available ruminant feed and to the process of making the feed according to the present invention .

The fat composition may be derived from any convenient fat source, and the fat may be both of animal and plant origin . The fats may be in the form of triglycerides , or they may be hydrolysed to free fatty acids or monoglycerides . An example of a preferred fat is palm oil .

During processing of feeds in the feed plant, water is added and temperature is increased in the process for the additional purpose of sterilizing feed and formation of pellets . Thus , it is possible to induce amylose/lipid complexes during feed processing . The beneficial effect of such a process is that it will not be necessary to alter the feed production process in order to form the inventive amylose/lipid complexes , but it can be beneficial to optimize the process such that an optimum level of amylose/lipid complexes may be formed. Such an optimum level of complexes is partly determined by the level of digestibility

of the feed that is wanted, and thus a custom-made feed may be made to be adapted to ruminants where the digestibility of the starch is to be altered . The determination of such an optimal level of starch/lipid complexes in the feed lies well within the purview of the person skilled in the art .

Examples

Example 1

A diet containing 70 % ground barley with a starch content of about 60% (including 25% amylose) was mixed with palm oil with a content of 400 g/kg palmitic acid such that the diet contained 5 % of this added fat (fat : amylose ratio = 1 : 0 , 5 ) . The feed was heated together with the fat through the addition of steam to a temperature of 75 ° C during intimate mixing with a paddle, followed by pelleting. The pro- duced feed is consumed by ruminants (cows ) in the same amount as conventional feed, and reduces the tendency of health deterioration in the animals .

Example 2

A diet containing 70 % ground barley with a starch content of about 60 % (including 25 % amylose) was mixed with palm oil with a content of 400 g/kg palmitic acid such that the diet contained 5 % of this added fat ( fat : amylose ratio = 1 : 0 , 5 ) . The feed was heated together with the fat through the addition of steam to a temperature of 75 ^° C during inti- mate mixing with a paddle, followed by expander treatment of the feed under pressure such that the temperature exceeded 100 ⁰ C, and thereafter pelleting . The produced feed is consumed by ruminants (cows ) in the same amount as conventional feed, and reduces the tendency of health deterio- ration in the animals .

Example 3

A diet containing 40 % ground barley and 40 % ground oats with a starch content of about 60 % (including 25 % amy- lose) was mixed with modified tallow with a content of 400 g/kg palmitic and stearic acid such that the diet contained 5 % of this added fat ( fat : amylose ratio = 1 : 0 , 5 ) . The feed was heated together with the fat through the addition of steam to a temperature of 75 ° C during intimate mixing with a paddle, followed by expander treatment of the feed under pressure such that the temperature exceeded 100 ° C, and thereafter pelleting . The produced feed is consumed by- ruminants ( cows ) in the same amount as conventional feed, and reduces the tendency of health deterioration in the animals .