IE41718B1 - Ruminant feed and method of producing same - Google Patents

Abstract

1505930 Ruminant feeds KANSAS STATE UNIVERSITY RESEARCH FOUNDATION 15 Sept 1975 [24 Feb 1975] 37767/75 Heading A2B A ruminant feed is made by admixing an ungelatinised starch bearing material selected from corn, sorghum, millet cassava, potatoes, jams, rice, corn starch, potato starch, wheat starch, arrow root, turnip, and rutabagus with an N.P.N. substance 0.25-10% of a lipid, based on the weight of starchy material, and a quantity of water; subjecting the mixture to heat, pressure and shear to cause at least partial gelatinisation of the starch and reaction of the NPN substance therewith; and releasing the pressure to give an expanded product. The N.P.N. substance may be urea, uric acid, biuret, ethylene urea, ammonium phosphate, bicarbonate, carbamate, citrate, formate, acetate, propionate, lactate, succinate, fumarate or maleate, diammonium phosphate, propionamide, butyramide, formamide, acetamide, dicyanodiamide, isobutane diurea, creatinine or creatine. The lipid may be an animal fat or grease, a vegetable oil or fat, or soybean lecithin. The heat treatment may be at 220-360‹F and 300- 500 psi followed by extrusion, which causes expansion. The protein equivalent may be 24- 125, the degree of gelatinisation 50-100%, and the final moisture content less than 15%. The mixed ingredients may be pre-treated with steam or water before heat treatment.

Description

This invention, relates to a ruminant feed and a method of producing same.

This invention relates to a reacted, palatable, nontoxic, processed food product for ruminant animals as well as to a process for producing the product wherein the feed composition contains modified, interacted energy and protein-producing constituents derived from a selected class of starch-bearing materials and a nonprotein nitrogenous (NPN) substance respectively.

It is concerned with such products which include a minor proportion of a lipid such as an animal fat which unexpectedly serves to greatly facilitate cooking, processing and handling of the feed.

It is known that nonprotein nitrogenous substances such as urea may he incorporated into feed for ruminants as replacement for protein sources therein.

Such added urea Or other NPN source is first degraded by rumen microorganisms to ammonia and the latter is then converted to microbial protein. A major portion of such microbial or bacterial protein is then enzymatically degraded to amino acids in the small intestine of the ruminant where, after being absorbed, they are available for use by the animal. As will be readily apparent, NPN supplementation of ruminant feed is extremely attractive from an economic standpoint, since relatively inexpensive materials such as urea can be fed in place of costlier natural proteins coming from traditional sources such for example as cereal grains. -241718 In practice, attempts at directly admixing raw urea and ruminant feed to supplement the protein level of the latter have met with a number of serious obstacles which have severely limited use of conventional NPN feeds.

For example, palatability and toxicity problems inherent in the addition of urea to cereal grains and other conventional feeds such as grasses, roughage and vegetable starches have drastically limited the amount of NPN that can be mixed with the normal feed ration. Generally, no more than about 4% by weight of urea can be directly added to raw ruminant feed compositions without undesirable results, because of toxic reactions, inefficient utilization of the urea, segregation of the constituents, unpalatability of the feed, and the tendency of the mixture to form a solid block by virtue of the hygroscopic nature of urea.

One extremely successful response to the problems outlined above is disclosed in British, Patent SpeoificSf edification ation No. 1,127,198. In particular, this patent/discloses that the amount of NPN added to ruminant feed can be greatly increased without attendant toxicity or unpalatability by combining NPN and a starch-bearing material such as corn and subjecting the admixture to high levels of heat, agitation, pressure and shear in the presence of sufficient water to assure gelatinization of the starch material. This process is advantageously carried out in an extrusion cooker and has the effect of producing a modified, reacted feed product which is characterized by an increase in the level of derivable bacterial protein along with a protein assimilability efficiency significantly greater than could be obtained in any simple ungelatinized mixture of the starch-bearing material and NPN -341718 source. Moreover, the reacted and combined constituents of the feed products of British Patent Specification No. 1,127,198 have been found to be hydrolyzable within the rumen of a ruminant animal at sufficiently similar rates to substantially increase the conversion of ammonia from the NPN constituent into microbial protein without significant resultant toxicity. The latter is important since rapid ammonia release in the rumen can lead to inefficient protein conversion, loss of ammonia through the elimination processes of the animal, and an increase in the chance of toxicity to the ruminant.

Although NPN-supplemented feed products produced in accordance with the methods of British Patent Specification No. 1,127,198 have experienced significant commercial acceptance on a worldwide basis, certain problems inherent in the cooking, processing and handling thereof have remained, especially when food sources such as tuber starches, waxy starch material or cereal starches with low levels of fat are employed, or when the starch source-urea ratios of the feed are of the order of 4 or less to 1. In such cases, the tendency of the starch-NPN admixture during extrusion cooking to surge and build up adjacent the extrusion die can make it difficult to control processing conditions for maximum conversion of the raw, ungelatin25 ized starch and raw urea to a desirable starch-controlledurea product exhibiting enhanced levels of ammonia conversion when subjected to rumen microorganisms. Por example, a characteristic of tuber and waxy starch-urea products is that they are plastic and adhesive and if cut at the face of the extruder die in the normal manner, the cut products will not separate from one another but will have a tendency to adhere to a previously cut segment or segments thus forming a continuous length of hot, plastic, sticky material that tends to foul the cutting knife and its Working parts. As can be appreciated, this condition often results in a failure to adequately process the feed due to the inability to efficiently handle the extruded material as it emerges from the cooker.

It will also be recognized that any attempted solution to the problems alluded to above must not appreciably affect the amount of bacterial protein which can be synthesized by the ruminant from the feed product. In addition, any expedient employed for solving such problems must not adversely affect the breakdown rate of the NPN substance and carbohydrate unpalatable to ruminants such as cattle, sheep and goats.

According to tiie present invention there is provided a method of producing a palatable, nontoxic ruminant feed product comprising the steps of: admixing a predetermined quantity of an edible, ungelatinized, starch· bearing food material selected from corn, sorghum, millet, cassava, potatoes, yams, rice, corn starch, potato starch, wheat starch arrowroot, turnips, rutabagus and mixtures thereof, a sufficient amount of water to permit gelatinization of at least a portion of said food material when the latter is subjected to elevated heat and pressure, a quantity of a nonprotein nitrogenous substance characterized by the property of being hydrolyzable to ammonia by rumen microorganisms and thereafter convertible to microbial protein and lipid in an amount of from 0.25 to 10% by weight of the food material; con30 tinuously moving the admixture into and through a treat ment zone while agitating tho admixture and subjecting the same to neat and high compression and shear forces for a period of time sufficient to gelatinize at least a portion of the food material in the presence of the . water while the food material is intimately intermingled and reacted with the nonprotein nitrogenous substance to provide a reacted composition; and suddenly releasing the pressure on said reacted composition as it continuously leaves the treatment zone to produce an expanded and gelatinized feed product.

The present invention provides a cooked, gelatinized, palatable, nontoxic, starch-NPN ruminant feed product, and method of producing same, which is characterized by an unexpected ease of cooking, processing and handling through the addition of a minor amount of lipid incorporated into the feed constituents prior to cooking thereof; the resultant feed is thereby capable of being efficiently cut, dried, crushed, stored and fed, and the feed has been found to release ammonia when subjected to rumen bacterial attack in a manner essentially equivalent to that of standard reacted starch-NPN feeds which are free of added lipid, such that the palatabxlity,. toxicity and ammonia release characteristics of the feeds hereof is not adversely affected.

The invention can also provide a starch-NPN feed product wherein the feed contains an amount of lipid such as an animal or — 6 vegetable fat which serves to synergistically maintain the microbial protein synthesis level of the feed when the latter is subjected to rumen microorganisms at a level approximately equal to or even better than the protein synthesis levels of otherwise identical products free of added lipid, even though the extent of starch damage and gelatinization within the feed is lessened by virtue of the lipid addition; thus, the feed products hereof are eminently suited to serve as high protein ruminant feed notwithstanding the fact that they are much easier to cook and process than many prior feeds utilizing starch-bearing sources known to present processing difficulties.

The presence of lipid in an amount of from 0.25 to 10% by weight based upon the starch-bearing material controls the tendency of some starch-bearing materials (such as tuber starch materials, low fat cereal starch materials and waxy starch materials) to build up adjacent the extruder die and emerge therefrom as a hot, plastic, adhesive mass which is difficult to cut and dry or otherwise further process.

The present method of producing the ruminant feed product allows the feed constituents to be extrusion cooked in the presence of greater quantities of moisture than heretofore practical with feeds of high protein equivalent values, so that the resultant feed products exhibit unexpectedly high levels of microbial protein synthesis while nevertheless retaining desirable handling characteristics. - 41718 The feed products of the present invention are advantageously processed in an expansion cooker such as a cooking machine of the extruder type. For purposes of example, the following discussion will center around commercial scale extruders of the type sold by the Wenger Manufacturing Company. Premixed starch-bearing material, water, a NPN substance and lipid are admixed and introduced into the elongated extrusion chamber of the cooker which is provided with-a primary extrusion head and an extruder cone terminating in an apertured extrusion die.

An auger conveyor of variable pitch is situated within the extruder so that the feed constituents are conveyed along the length of the extruder while being subjected to high pressure, shear and compressive forces. Heat is conventionally supplied by way of steam jackets surrounding at least the extrusion head and cone sections of the cooker.

In addition, many such extruders are provided with preconditioners including a hopper for introducing the feed constituents into the unit and an elongated zone provided with a central auger, discontinuous conveyor flights or paddles for moving the material towards the communicating inlet of the primary extruder section, A further description of an exemplary extrusion cooker suited for use in the methods of the present Invention can be found in the disclosure of U,S, Patent No. 3,642,289, It is to be understood however, that other types of extrusion cookers, such as those sold by the Anderson, I,E,E,C,, Company can also serve the purposes of the present invention.

Feed constituents added to an extruder of the type described are continuously moved through the machine while being subjected to agitation, heat, high compression and shear so that at least a portion of the starch-bearing - 8 food material is disrupted and allowed to intermingle and react with the NPN source to provide the reacted ruminant feed compositions hereof. At the extrusion end of the cooker the pressure on the product is suddenly reduced to atmospheric so that an expanded and gelantinized feed product results.

Lipid addition has been found to make the cooked, reacted end product much easier to handle, cut and further process as needed. In addition, it has unexpectedly been j_q found that such lipid addition serves to synergistically maintain the microbial protein synthesis level of the feed at levels approximately equal to or in some cases greater than the levels of otherwise identical feeds free of added lipid. As can be appreciated, addition of a lipid (such as an animal fat for example) would predictably have the - 9 41718 effect of drastically lowering both the extent of starch disruption and gelatinization, and concomitantly the bacterial protein level of the resultant feed, since the fat should provide a lubrication of sorts causing the unreacted admixture to pass through the extruder without sufficient starch distruption and gelatinization. This should in turn result in lowered protein synthesis when the feed is subjected to rumen microorganisms, since the extent of such synthesis is in general directly related to the degree of starch gelatinization.

To the contrary however, actual test results have demonstrated that the predicted results do not obtain, but rather the resultant feed in general Taaintains the desirable high levels of derivable microbial protein needed for economically feasible products . Although not completely understood, it is believed that lipid addition in some manner synergistically acts on the other feed constituents to yield the results alluded to above.

Moreover, lipid addition in some instances permits extrusion cooking of the feed constituents in the presence of greater quantities of water than has heretofore been feasible, and this is likewise believed heneficial in maximizing the level of protein synthesis derivable from the feed. For example, while it has heretofore not been practical to process - starch-NPN ruminant feeds of economically attractive protein equivalents in the presence of moisture levels greater than about 30% by weight, addition of a minor amount of a lipid to the feed constituents during extrusion cooking allows the moisture content to be at a level of from 4 to 50% by weight, more preferably at a level of from 10 to 35% by weight, and most preferably from 15 to 25% by weight.

Starch-bearing materials particularly adapted for use in the present invention may be selected from, sorghum, millet, cassava (tapioca) , potatoes, yams, rice, corn starch, potato starch, wheat starch, arrowroot, turnips, rutabagus and mixtures thereof. Although carhohydrate starch-bearing materials other than those listed above can be processed with additional lipid in accordance with the invention, many of such other products contain sufficient natural lipid or otherwise can be handled by known means. In addition, it will be clear that certain samples of the listed materials may need greater or lesser quantities of added lipid depending principally upon the individual characteristics and makeup of the samples. The starch-bearing materials are preferably in comminuted form (e.g., grain should be ground in order to give an average particle size of about 450 microns or less) so that water and/or steam blended with the mixture in the preconditioning or extruder zone of the extrusion cooker is brought into intimate contact with the starch-bearing material to facilitate gelatinization thereof.

A wide variety of NPN substances can also be employed in the present invention, with the preferred sources including urea, uric acid, biuret, ethylene urea, ammonium phosphate, ammonium bicarbonate, ammonium carbamate, ammonium citrate, ammonium formate, ammonium acetate, ammonium propionate, ammonium lactate, ammonium succinate, ammonium fumarate, ammonium malate, diammonium phosphate, propionamide, butyramide, formamide, acetamide, isobutane diurea, dicyanodiamide, creatinine and creatine. Urea is the most preferred NPN source however, because of its relatively low cost and high nitrogen content.

Similarly, a wide variety of lipid can be utilized to good effect in the invention, but preferred lipids are taken from the group consisting of animal fats, animal greases, vegetable fats, vegetable oils and soybean lecithin. One particularly preferred lipid source is a mixture of animal and vegetable fat sold under the tradename HEF by the Procter and Gamble Company of Cincinnati, Ohio.

Lipid in the form of animal and vegetable fats is preferably added in liquid form to the starch and NPN substances prior to extrusion cooking. In this connection it has been found that a lipid addition of from 0.25 to 10% by weight meets the requirements of the present invention, and more preferably the added lipid ranges from 0.5 to 6.0% by weight. Most preferably, the lipid addition is from 0.5 to 4% by weight, all figures based on the weight of the starch-bearing carbohydrate substance.

Although the ratio of NPN to starch-bearing material may be varied as dictated by price considerations, -availability of constituents, processing requirements, and ultimate end use parameters, the proportions are advantageously maintained within certain limits not only from the standpoint of operability but also commercial feasibility. For example, unless sufficient NPN is provided in the initial mixture to warrant inclusion thereof from an economic as well as a nutritional standpoint, the cost of processing the constituents is prohibitive. On the- other hand, if the quantity of NPN present in the admixture is increased to a level where the final product is unpalatable even in a processed condition because of excess NPN and the composition is completely unmanageable in use, then the processed product has no significant utility as a ruminant feed. In the latter connection, it has been found that the present invention involving addition of lipid permits use of starch source5 urea ratios on the order of 4 or less to 1, which can be a significant advantage to livestock feeders since the additional NPN serves as an extremely inexpensive protein source.

In particular, it has been found that addition 10 of lipid such as animal fat permits utilization of starch-NPN ratios yielding protein equivalent (P.E.) levels of between 24 to 125. Illustrative NPN compounds usable in the present invention and the preferred ranges thereof in the final starch reaction NPN product are set forth in Table I hereunder, where the percentage of NPN is compared with a predetermined quantity of grain sorghum: Ό Φ Ρ CJCM fl] Ρ Φ U * 5 Α Ο ϋ Ρ Ρ ΡΜ £3 Ρ4 Α Ό ϋ Φ Ρ ό d *3 Ρ < w τι d ta φ ο ο 9- * S ό ο ο α ρ * fr ο 0 ρ Ρ υ . 3 U3 *3 ω Ο Ή Ρ Φ pit 3 Ό 3 φ Φ Ρ U Ο Ρ d Φ Φ fr & *α ιρ Ο Ο Λ S »Η ο ts3 U β Ό Φ 3 P 3 3 O 0 3. P U 0 3 Ο Φ 3 O U Φ P MZ Φ O PM fP P 0 ΙΛ ιη CM CM rH fH CM Γ* co d m sf o\ o m σι m m in η* *ί »D σι o I*.

KO H cn CM >» cn o CM 18.41 115.06 14.1 109.4 24 125 - 14 μ UN 3 4-» □ 3 4-1 Φ υ Cd 3 43 na 0 υ μ μ Ρμ 3 U ζ W Pm «4· CN in CN «4CN in CN CN m CN m CN m m CN CN •4· NT CN CN c4 CN CN Nf CN m in CN CN •41 CN «4CN m CN «4· CN 41*718 TABLE I (Cont. 4= 4-) *3 U Φ μ Φ μ 3 43 Ό 3 Ό ϋ£ Ό μ 0 •rt < W μ Φ Ρμ JS rQ 3 3 Ζ 3 Φ Ρμ Ρ 0 U Ζ CL 3 μ s *3 Ό 3 0 0 Φ Φ 0 μ μ Φ Ρμ U μ ζ 3 φ Ρμ 0 Φ Ρμ Ζ μ Ρ4 . o c o. φ B u Ο H 0 0) Pm Z T3 O Oh 4-) B 3 “ O 0 0 μ Φ Ζ <ϋ 00 g Pm μ AJ IM •rt 0 z CN CH ST o cn ch σ oo vo cn o ‘O \o CN Ό 00 m kO cn m < co co o m cn vo O «4oo m •4kO d m CN m oo kO m CN cn co 0s* o m o o oo cn Ch m cn oo ST Ch CN cn CN f-H cn o o CN rH o cn m kO o rH CN «4· cn r-} o CN οο .3 >> μ Pt cn in m r-. ι—ι o cn r** cn cn cn cn cn cn cn cn «4· kO k© kO co t—M CN cn •Η μ οο Β I μ ο »0 Ή CJ < ω μ φ μ ο Π3 Ή U π) U •ρΜ μ Ρ πθ •rt Β •rt •σ Ο C ο •Η η Φ r—1 3 .3 Ρ σ’ W •rt Φ μ Ο μ Ρμ As is apparent from the above Table, the total P.E. of the starch reactant-NPN product is preferably maintained within the range of 24 to 125, based upon the weight of the starch material, For the listed NPN sources, this would amount to a percentage addition range of from -3.5 (dicyandiamide) to 173 (ammonium phosphate). More preferably, the P.E, level of the feed products hereof is maintained within the range of about 60 to 125, and most preferably in the range of from about 85 to 125.

The amount of moisture required in the mixture of starch-bearing material and NPN to assure necessary gelatinization of the starches is variable within certain limits, but is preferably within the range of from 4 to 50% by weight based upon the weight of the starchbearing material. Most starch-hearing materials inherently contain a certain amount of water as a part thereof and this quantity is included in the moisture content of the admixture ready for processing. For example, dry com may contain 12 to 14% moisture and this quantity is taken into account in determining the amount of water to be added to the mixture prior to processing thereof. Sufficient water must be available in the mixture of starch-bearing material and NPN to cause at least a portion of the starch to become disrupted and thereby gelatinized upon heating in the presence of the water to thus produce a gel structure. In preferred forms however, the total moisture level and other relevant processing conditions are adjusted such that the starch-bearing feed material is from 50 to 100% gelatinized. More preferably, this level is from 75 to 100% gelatinization, and most preferably from 90 to 100% gelatinization. In addition, the total - 16 41718 moisture content is preferably in the range from 10 to 35% by weight, and most preferably from 15 to 25% by weight.

Xn practice, the starch-bearing material, NPN source, and lipid are initially admixedby conventional means and thereafter delivered to the inlet of an extrusion cooker for processing thereof, whereupon water is added to the mixture in the form of steam and/or water. In certain cases, it may be advantageous to precondition the admixture in a preconditioning zone wherein water and/or steam is blended therewith prior to the actual extrusion treatment. In any event, the feed constituents are conveyed along the length of the extruder by means of the central auger conveyor while the constituents are subjected to high temperature, shear, pressure and compressive forces. The temperature of the composition is gradually increased as it approaches the end die, so that the temperature thereof immediately prior to extrusion is preferably from 220 to 36O°F. The extrusion die and auger also cause pressures to be developed within the extruder on the order of from 300 to 5OOpsi, and such pressures are thereby maintained on the composition as it moves through the extruder section in order to facilitate relatively quick and complete processing.

The extruded product emerging from the extruder die is in the form of elongated rods which are preferably cut by conventional means (e.g., a variable speed knife) to a suitable size and finally dried to a moisture level of less than 15% by weight (and preferably less than about 6% by weight). In some instances, the dry product may be subjected to well-known crushing techniques in order to obtain a granular product for easier handling. - 17 41718 The following Examples describe embodiments of the present invention but are not to be taken as a limitation on the scope thereof.

EXAMPLE I In these tests a series of tuber starch-urea feed products were prepared in accordance with the invention hy incorporating within the normal feed constituents varying amounts of liquid fats in order to determine the cooking and handling qualities of'the end products as well as the microbial protein synthesis levels thereof, In particular, predetermined quantities of ground potato and tapioca were mixed with the specified levels of water, urea and fat as listed in Table II hereunder. The fat was heated to liquid form and was the HEF product sold by the A Procter and Gamble Company, The feed constituents were thoroughly mixed in a conventional blender and subsequently passed through a Wenger Model X-25 extrusion cooker (or in some cases through a Brabender laboratory size cooker) without preconditioning in order to provide the lipid-modified starch-NPN ruminant feed products of the instant invention. In this connection, attempts at producing feed using potato and tapioca starch materials with no added fat led to clogging of the extruder and a wholly unsatisfactory product; consequently, no data was derivable from such runs, which emphasized the need for lipid addition in processing starch sources in accordance with the invention. The cook temperatures referred to are those measured immediately prior to extrusion. The results of this series of tests are summarized in the following Table II: TABLE II Protein For Cook .89 .25 90' .75 .84 .18 1 1 | .23 «Η Ό «Η Γ*- CO o 1 cn CO Φ © rH © 00 1 cn Ή 44 Μ U (Η H Φ Φ 44 U υ h (0 0 CQ CJ 1 ·§ O' rH lO cn m m © rH Ph Η CM © co © tn LO W Ο 00 © © en 6 LO cn <Ν 5» £ ΙΛ 00 LO rd iH cn CM 0 CO CM LO cn 00 1 f o ο ο Ο m LO © 00 MT 1 rH © r«* Γ-» r» ΓΉ rr 1 Γ δ* Φ Ό CM CO 00 CM CM CM lO Φ Ο o © m CM lO ¢0 lO Η © ι/Ί LO lO co © cn lO CM «Η rH h rH Η rH H rH 44 (0 Ο O o O O m O in fr Η CM < CM rH Mf LO Η iter led 00 © m © 00 © © © rt Τ3 ►S Ό <Γ O CM © CO cn CO < Η rH rH iH rH CM CM CM . Η to 44 ιη © © O © O CM O 0 · •Η m Mt © 00 CM cn CM 0 Pr Ο Β cn CM CM CM CM cn cn cn Φ Η 44 υ β Ό ο co rt CO Η « rt u y o to 0 0 0 u u 0 0 o 44 44 4J 0 0 •ri •ri •ri Ό co cO CO •ri •H Pr Pr pr 0 44 44 44 Pr P. CO CO rt 0 0 0 0 CO' CO Eh Eh to to pH pH EH Eh rH rH iH Μ Φ Ο Ο U »4 Ο 4J CO Ο «α CO rH Μ φ Ό ΰ φ *3 Ρ Μ Ό φ S Μ Ο Φ Λ ΕΗ β •Η Φ Ο Μ Pr Η Φ •Η Η Φ 4J U CO rO Φ Φ *> ' A study of the foregoing data will demonstrate that addition of from 1 to 4% fat in the starch-NPN admixture synergistically enhances the microbial protein content derivable from the resultant feed product. In particular, addi5 tion of fat served in every case to lower the percent cook value (a measure of starch gelatinization) of the samples, since suoh fat serves as a lubrication for the extrudate and thus lessens the amount of starch disruption and gelatinization. However, the tests also indicate that the extent of protein synthesis was not adversely affected in any appreciable manner by lower cook values, but in fact was substantially maintained or even increased by virtue of fat addition. Attention is directed to the right-hand column of Table II wherein bacterial protein synthesis is corrected for the degree of cook (B.P./% cook), thus giving a measure of the true efficiency of the process as the cook values in the runs were different. This data clearly demonstrates that although cook values decrease with added lipid, the protein synthesis levels derived from the samples are unexpectedly 2o increased. Although not completely understood, it is evident that added lipid synergistically acts with the other feed constituents to achieve the results alluded to above.

In this connection, it will be understood the rumen fermentation in a live animal is a dynamic process where ammonia is constantly being produced, metabolized, adsorbed or removed. The concentration of ammonia or microbial protein in the animal at a given time can depend upon all of these factors. High rumen microbial protein concentration may result from slower microbial protein removal from the rumen, and therefore, not really reflect increased microbial protein synthesis. In order to obviate this factor in vitro fermentation studies discussed above were undertaken to develop the microbial bacterial - 20 41718 protein synthesis data presented. In the in vitro fermentation, ammonia cannot leave the rumen hy adsorption or passage and microbial protein cannot leave by passage. Therefore, the ammonia levels and microbial protein levels of the in vitro studies represent an easy method for accurately determining protein synthesis.

In practice, samples of the control and test feed products were placed in identical quantities of rumen fluid and allowed to ferment for equal periods of time.

The total protein levels derived from such fermentation were then measured, and following correction for the protein equivalent from the feed protein and rumen fluid, the microbial protein synthesis levels were determined.

This series of tests also demonstrated that the processed feeds hereof containing lipid were much'easier to process and handle. Specifically, the added lipid did not exhibit the property of adhering to the die and knife mechanism but rather could be quite easily cut into discrete pieces to greatly facilitate further drying and treatment.

EXAMPLE II In this example additional starch-bearing materials were tested in order to demonstrate the utility of added fat in various other NPN-starch admixtures. In particular, the test proceeded exactly as described in connection with Example I with varying levels of fat, urea, and water being processed in the Wenger extruder.

In addition, cook temperatures were varied to determine optimum operating conditions. The data summarizing this series of tests is set forth in the following Table III: - 21 41718 Φ μ Λ! « Ο Ο ΟΡΟ ρ υ ΡΜ *Φ φ Η 41 Ο Φ U •rt Φ Φ Ρ Ρ Φ Φ Ρ Ρ jj ο ω α ο φ to Q w m © co tA ο νο © CO cn m t0 -3* tO ia htO CM VO tO Γ-.

VO co r>. tO CM rrt CM VO ov © rrt vA tO >. rrt tO CO © co to rrt m co rtf σ r*.

Ov to VA CM r*» «Α σ> co iA O CO «Α CO CM ID rtf σ *3lA CM »A rt CM lA rt CM « •ίΟ σ Γ*· © rt ο m Γ*vo © rt ΐΑ CM t's rt IA VO rt co vO CO o σ co VO vo co CO CM rt b00 r*.

CM CO σ σ © IA co σ r*. vo σ © IA CM rt vO vo CM r> © σ CM vA co CM © o co VA IA CM © CM VA CO CM VA CO CM O rt CO o o co ΙΟ· c r r. c P q. ( c i~ c f c c r V rt - 22 41718 An analysis of Table III will demonstrate that fat addition serves to at least substantially maintain and in most cases actually increase the microbial protein level of the resultant feed products. In order to demonstrate the effectiveness of lipid addition in this context, the cook values associated with each of the runs of this example have been calculated and are presented in Table III, along with the bacterial protein synthesis levels corrected for the degree of cook. These figures are indicative of the extent of gelatinization of the starch-bearing material in each test, with higher magnitude numbers representing greater gelatinization. In this connection it will be noted that in all cases additional fat served to substantially maintain or increase the cook-corrected protein synthesis level notwithstanding the fact that cook values go down with such fat addition. Thus, it is eyident that the lipid addition · served to synergistically enhance microbial protein synthesis.

Finally, the products of these tests were also very easy to cut, dry, handle and store and accordingly are preferred over otherwise identical feeds of the prior art which are free of lipid addition.

EXAMPLE III In this test separate corn samples were employed as the starch-bearing material in order to demonstrate the utility of the present invention in connection with waxy materials. In particular, samples 1-4 contain 8.9% protein and 14.4% moisture, whereas samples 5 and 6 contain about 8,9% protein and 15,04%. moisture. In all other respects, tests of this example were identical with those undertaken in Examples II above. A study of Table IV hereunder will again demonstrate the unexpected finding that while fat addition lowers cook value, the protein synthesis derived from the feed is not adversely affected but rather is increased. Moreover, the resultant feed products are very easy to process and in every way represent commercially salable feeds. As such, the synergistic nature of lipid addition as herein set forth is conclusively demonstrated.

Claims (23)

1. CLAIMS:1. A method of producing a palatable, nontoxic ruminant feed product comprising the steps of: admixing a predetermined quantity of an edible, ungelatinized, starch5 bearing food material selected from corn, sorghum, millet, cassava, potatoes, yams’, rice, corn starch, potato starch,· wheat starch, arrowroot, turnips, rutabagus and mixtures thereof, a sufficient amount of water to permit gelatinization of at least a portion of said food material when the 10 latter is subjected to elevated heat and pressure, a quantity of a nonprotein nitrogenous substance characterized by the property of being hydrolyzable to ammonia by rumen microorganisms and thereafter convertible to microbial protein, and lipid in an amount of from 0.25 to 15 10% by weight of the food material}continuously moving the admixture into and through a treatment zone while agitating the admixture and subjecting the same to heat and high compression and shear forces for a period of time sufficient to gelatinize at least a portion of the food 20 material in the presence of the water while the food material is intimately intermingled and reacted with the nonprotein-nitrogenous substance to provide a reacted composition; and suddenly releasing the pressure on said reacted composition as it continuously leaves the treat• ί 25 ment zone to produce an expanded and gelatinized feed product.

2. A method as claimed in Claim 1, wherein said nonprotein nitrogenous substance is selected from urea, uric acid, biuret, ethylene urea, ammonium phosphate, ammonium bicarbonate, ammonium carbamate, ammonium citrate, ammonium formate, ammonium acetate, ammonium 5 propionate, ammonium lactate, ammonium succinate, ammonium fumarate, ammonium malate, diammonium phosphate, propionamide, butyramide, formamide, acetamide, dicyanodiamide, isobutane diurea, creatinine and creatine

3. A method as claimed in claim 2 wherein the 10 non-protein nitrogenous substance is urea.

4. A method as claimed in Claim 1, 2 or 3, wherein the water content in the admixture is from 4 to 50% hy weight, based upon the quantity of food material

5. A method as claimed in Claim 4, wherein the 15 water content is from 10 to 35% by weight

6. A method as claimed in Claim 5, wherein the water content is from 15 to 25% by weight,

7. A method as claimed in any one of the preceding claims, wherein the lipid content in' 20 the admixture is from 050 to 6.0% by weight.

8. A method as claimed in Claim 7, wherein the lipid content is from 0.50 to 4.0% by weight. - 27 41718

9. A method as claimed in any one of the preceding claims, wherein the temperature of the reacted composition immediately prior to leaving the treatment zone is from 220 to 360° F. 5

10. A method as claimed in Claim 9, wherein the temperature of the reacted composition is from 270 to 340F.

11. A method as claimed in Claim 10, wherein the temperature of the reacted composition is from 300

10. To 330°F.

11. 12. A method aB claimed in any one of the preceding Claims, wherein said nonprotein nitrogenous substance is present in such an amount that the feed product has a protein equivalent level of from 24 to 15 125.

12. 13. A method as claimed in Claim 12, wherein the protein equivalent level is from 60 to 125.

13.

14. A method as claimed in Claim 13, wherein the protein equivalent level is from 85 to 125. 20 .

15. A method as claimed in any one of the preceding Claims, wherein the pressure within the treatment zone is maintained at a level of from 300 to 500 p.s.i.

16. A method as claimed in any one of the preceding - 28 41718 Claims, wherein said lipid is selected from animal fats, animal greases, vegetable fats, vegetable oils and soybean lecithin.

17. A method as claimed in Claim 16, wherein 5 said lipid comprises a mixture of animal fat and vegetable fats and is added to the admixture in liquid form.

18. A method as claimed in any one of the preceding Claims, which includes the steps of; advancing 10 the admixture through a preconditioning zone prior to introduction thereof into the treatment zone and introducing into the preconditioning zone a fluid selected from steam and water and mixtures thereof for blending with the admixture.

14. 15

19. A method as claimed in any one of the preceding Claims, including the step of drying the expanded and gelatinized feed product to a moisture level of less than 15% by weight, based upon the quantity of food material. 2o

20. A method as claimed in Claim 19, wherein said moisture level is less than 6% by weight.

21. A method as claimed in any one of the preceding Claims, which includes the step of comminuting the expanded and gelatinized feed product. 29 41718

22. A method of producing a palatable, non-toxic ruminant feed product as claimed in Claim 1 substantially as hereinbefore described with reference to any one of the Examples.

23. A palatable, non-toxic ruminant feed product whenever produced by the method claimed in any one of the preceding claims.