CA1046336A - Extrusion processed starch-npn ruminant feed and method of producing same - Google Patents

Abstract

A gelatinized, palatable, nontoxic extrusion cooked ruminant feed is disclosed which contains a disrupted starch-bearing food source reacted with a nonprotein nitrogenous substance (NPN) and a quantity of lipid material such as animal fat which serves to greatly facilitate product performance and handling of the feed, especially when certain tuber or waxy starch materials are used therein or in the case of high pro-tein equivalent feeds where the starch-bearing material-NPN
(preferably urea) ratio is on the order of 4 to 1 or greater.
In addition, lipid addition synergistically acts to yield cooked products exhibiting derivable bacterial protein levels approxi-mately equal to or better than otherwise identical feeds free of added lipid notwithstanding the fact that extent of starch disruption and consequent gelatination within the feed is normally decreased by virtue of the lipid addition. In pre-ferred forms, lipid in the form of animal fat or the like is added to the feed constituents in liquid form and in amounts ranging from 0.25 to 10% by weight prior to cooking of the feed in a conventional extrusion cooker, and the expanded and gelatinized cooked product is thereafter cut and dried to its final form as ruminant feed which can easily be shipped, stored and fed to ruminants as a high protein food source.

Description

lO~G;~36 EXTRUSION PROCESSED STARCH-NPN RUMINANT FEED
AND METHOD OF PRODUC ING SAM:E

This invention relates to a re~cted, p~lat~ble, non-toxic, processed food product for ruminant animals as well as to a process for producing the product wherein the feed compo- -sition contains modified, interacted energy and protein-produc-ing constituents derived from a selected class of starch-bearing materia.ls and a nonprotein nitrogenous (NPN) substance respec-tively. More particularly, it is concerned with such products which include a minor proportion of a lipid material such as an anlmal fa.t which unexpectedly serves to greatly facilitate cooking, processing and handling of the feed without a concomi-tant decrease in other desirable feed properties such as the microbial protein synthesis level thereof.
It is known that nonprotein nitrogenous substances such as urea may be incorporated into feed for ruminants as replacement for protein sources therein. Such added urea or other NPN source ls 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 rumina.nt where, after being absorbed, they are available for use by the animal. As will be readily apparent, NPN supple-~entation of ruminant feed is extremely attractive from an eco-nomic standpoint, since relatively inexpensive materials such as urea can be fed in place of costlier natural protelns coming from traditional sources such as cereal grains or the like.
In practlce, 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 (Dkt. #15499) ~ :

3.046~36 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 hydroscopic nature of urea.
0~ extremely successful response to the problems out-lined above is disclosed in U. S. Patent No. 3,624,489. In par-ticular, 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 i8 advantageously carried out in an extrusion cooker and has the effect of producing a modified, reacted feed product which is characterized by an increa~e in the level of derivable bacterial protein along with a protein assimilability efficiency significant-ly greater than could be obtained in any simple ungelatinized mixture of the starch-bearing material and NPN source. Moreover, the reacted and combined constituents of the feed products of U. S. Patent No. 3,642,489 have been found to be hydrolyzable with-ln the rumen of a ruminant anlmal at æufficiently 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 Patent No. 3,642,489 have experienced significant commercial acceptance on a worldwide basis, certain problems lnherent in the cooking, processing and handling thereof have remained, especially when food sources such as tuber starches, waxy starch materials or cereal starches with low levels of fat are employed, or when the starch source-urea ratios of the feed are on the order of 4 to 1 or greater.
In such cases, the tendency of the starch-NPN admixture during extrusion cooking to surge and build up ad~acent the extrusion die can make it difficult to control processing conditions for maximum conversion of the raw, ungelatinized starch and raw urea to a desirable starch-controlled-urea product exhibiting enhanced ~
levels of ammonia conversion when subjected to rumen micro- -organisms. For 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 ln 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 solu-tion to the problems alluded to above must not appreciably af-fect the amount of bacterial protein which can be synthesized by the ruminant from the feed product. In addition, any ex-pedient employed for solving such problems must not adverselyeffect the breakdown rate of the NPN substance and carbohydrate material or otherwise render the feed product toxic or unpalatable ~0'~336 to ruminants such as cattle, sheep and goats.
It is therefore the most important object of the present invention to provide a cooked, gelatinized, palatable, nontoxic, starch-NPN ruminant feed product and method of pro-ducing same which is characterized by an unexpected ease of cooking, processing and handling through the addition of a minor amount of a lipid material incorporated into the feed constituents prior to extrusion 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 sub~ected to rumen bacterial attack in a manner essen-tially equivalent to that of standard reacted starch-NPN feeds which are free of added lipid, such that the palatability, toxicity and ammonia release characteristics of the feeds hereof is not adversely affected.
Another important object of the invention is to pro-vide a starch-NPN feed product and method wherein the feed con-tains an amount of lipid suvh as an animal or vegetable fat which serves to synergistically maintain the microbial protein synthesis level of the feed when the latter is sub~ected to rumen micro-organisms at a level approximately equal to or even better than the protein synthesis levels of otherwlse identical products free of added lipid, even though the e~tent 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.
Another ob~ect of the invention is to provide a re-acted starch-NPN ruminant feed product which includes an amount of added fat from about 0.25 to 10~ by weight based upon the - -starch-bearing ma.terial, in order to control the tendency of some starch-bearing materials (such as tuber starch materials, low fat cereal starch materials and waxy starch materials) to build up ad~acent the extruder die and emerge therefrom as a hot, plastic, adhesive mass which is difficult to cut and dry or otherwise further process.
A still further object of the invention is to provide a high protein equivalent starch-NPN ruminant feed product and method wherein lipid addition permits extrusion cooking of the -feed constituents 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 desira.ble handling characteristics.
- The feed products of the present invention are ad- ` -vantageously processed in an expansion cooker such as a cooking machine of the extruder type. For purposes of example, the followlng discussion will center around commercial scale ex-truders of the type sold by the Wenger Manufacturing Company.
Premixed sta.rch-bearing material, water, a NPN substance and lipid material are admixed and introduced into the elongated extrusion chamber of the cooker is provided with a primary ex-trusion head and an extruder cone terminating in an apertured extruæion die. An auger conveyor of variable pitch iB situated within the extruder so that the feed constituent6 are conveyed along the length of the extruder while being subjected to high presæure, shea.r and compressive force.s. Heat is conventionally supplied by way of steam jackets surrounding at least the extru-sion head and cone sections of the cooker. In addition, many such extruders are provided wi~h preconditioners including a hopper for introducing the feed constituents into the unit and an elongated zone provided with a central auger, discontinuous 10~36 conveyor flights or paddles for moving the material toward 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 dis-closure 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.B.E.C., Company can also serve the pur-poses of the present invention.
Feed constituents added to an extruder of the type described are continuously moved through the machine while be-ing sub~ected to agitation, heat, high compression and shear so that at least a portion of the starch-bearing 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 gelati-nized feed product results.
In general, the method of the present invention involves admlxlng a predetermlned quantlty of an edlble, ungelatinized -starch-bearing food material with sufficient water to perm~t gelatlnlzation thereof and a nonprotein nitrogenous substance characterlzed by the property of being hydrolyzable to ammonia by ruminant microorganisms. Finally, a minor proportion of a lipid materlal sufficient to facilitate cooking and subsequent handling of the feed product is added to the initial admixture and the latter is thoroughly mixed. The second step of the method invol~es contlnuously movlng the mixture ~nto and through a treat-ment zone (e.g., an extrusion cooker) while agitating the admix-ture and sub~ecting the same to a source of heat and high pres-sure compression and shear forces for a period of time sufficientto disrupt and gelatinize at least a portion of the food material and thereby permit reaction thereof with the NPN source. ;

: ~

la4~336 Lipid addition has been found to make the cooked, reacted end product much easier to handle, cut and further pro-cess as needed. In addition, it has unexpectedly been found that such lipid addition serves to synergistically maintain the microbial protein synthesis level of the feed at levels approxi-mately equal to or in some cases greater than the levels of otherwise identical feeds free of added lipid. As can be ap-preciated, addition of a lipid (such 8S an animal fat for example) would predictably have the effect of drastically lowering both the extent of starch disruption and gelatinization, and concomi-tantly the bacterial protein level of the resultant feed, since the fat should provide a "lubrication" of sorts causing the un-reacted admixture to pass through the extruder without sufficient starch disruption and gelatinization. This should in turn re- -sult in lowered protein synthesis when the feed is subjected to rumen microorganism~, 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 predlcted results do not obtain, but rather the resultant feed in general maintains 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 quantitles of water than has heretofore been feasible, and thls is likewise believed beneficial in maximizing the level of protein synthesis derivable from the feed. For example, while it has heretofore not been practical to process a starch-NPN ruminant feeds of economically attractive protein equiva-lents in the presence of moisture levels greater than about 30 ~046336 by weight, addition of a minor amount of a lipid to the feed constituents permits a total water fraction (derived from added water and the native moisture present in the feed constituents) during extrusion cooking to be at a level of from about 4 to 50~ by weight, more preferably at a level of from about 10 to 35~ by weight, and most preferably from about 15 to 25~ by weight.
Starch-bearing materials particularly adapted for use in the present invention may be selected from the group consist-ing of corn, sorghum, millet, cassava (tapioca), potatoes, yams, rice, corn starch, potato starch, wheat starch, arrowroot, turnips, rutabagas and mixtures thereof. Although carbohydrate 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 indivldual characteristics and makeup of the samples.
The ~tarch-bearing materials are preferably in comminuted form (e.g., grain ~hould be ground in order to give an average par-ticle size of about 450 microns or less) so that water and/or steam blended with the mixture in the preconditioning or ex-truder zone of the extrusion cooker ls brought into intimate contact with the starch-bearing material to facilitate gelatini-zation 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, am-monium bicarbonate, ammonium carbamate, ammonium citrate, am-monium formate, ammonium acetate, ammonium propionate, ammoniumlactate, ammonium succinate, ammonium fumarate, ammonium malate, diammonium phosphate, propionamide, butyramide, formamide, aceta-mide, isobutane diurea, dicyanodiamide, creatinine and creatlne.Urea is the most preferred NPN source however, because of its relatively low cost and high nitrogen content.
Similarly, a wide variety of lipid materials 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 parti-cularly preferred lipid source is a mixture of animal and vegetable fat sold under the trademark HEF by the Proctor 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 about 0.25 to 10% by weight meets the requirements of the present invention, and more preferably the added lipid ranges from about 0.5 to 6.0% by weight. Most preferably, the lipid addition is from about 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 pro-cessed condition because of excess NPN and the composition is completely unmanageable in use, then the processed product has 'A~ '`~ g 10~6336 no significant utility as a ruminant ~eed. In the latter con-nection, it has been found that the present invention involving addition of lipid permits use of starch source-urea ratios on the order of 4 to 1 or greater, which can be a significant ad-vantage to livestock feeders since the additional NPN serves as an extremely inexpensive protein source.
In particular, it has been found that addition of lipid material such as animal fat permits utilization of starch-NPN ratios yielding protein equivalent (P.E.) levels of between about 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:

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~04'~336 As is apparent from the above Table, the total P.E.
of the starch reactant-NPN product is preferably maintained within the range of about 24 to approximately 125, based upon the welght of the starch material. For the listed NPN sources, this would amount to a percentage addition range of from about 3.5 (dicyanodiamide) to about 173 (ammonium phosphate). More preferably, the P.E. level of the feed products hereof is main-tained 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 gelatiniza-tion of the starches is variable within certain limits, but is preferably within the range of from about 4 to 50~ by weight based upon the weight of the starch-bearing material. Most starch-bearing materials inherently contain a certain amount of water as a part thereof and this quantity is included in the ; molsture content of the admixture ready for processing. For example, dry corn may contain 12 to 14~ moisture and this quantity 18 taken into account in determlning 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 ma-terial and NPN to cause at least a portion of the starch to be-come disrupted and thereby gelatinized upon heating in the presence of the water to thus produce a gel structure. In pre-ferred forms however, the total moisture level and other relevant processing cond~tions are ad~usted such that the starch-bearing feed material is from about 50 to 100~ gelatinized. More prefer-ably, this level i8 from about 75 to 100% gelatinization, and most preferably ~rom about 90 to 100% gelatinization. In addition, the total moisture content is preferably in the range from about 10 to 35~ by weight, and most preferably from about 15 to 25 by weight.

~04t~336 In practice, the starch-bearing material, NPN source, and lipid material are initially admixed by 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 precondition-ing zone wherein water and/or steam is blended therewith prior to the actual extrusion treatment. In any event, the feed con-stituents are conveyed along the length of the extruder by means of the central auger conveyor while the constituents are sub-~ected to high temperature, shear, pressure and compressive forces. The temperature of the composition is gradually in- ~ -creased as it approaches the end die so that the temperature thereof immediately prior to extrusion is preferably from about 220 to 360 F. More preferably, this extrusion temperature ranges from about 270 to 340 F., and most preferably from about 300 to 330 F. The extrusion die and auger also cause pressures to be developed within the extruder on the order of from about ; 300 to 500 p8i, 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 lerel of less than about 15% by weight (and preferably less than about 6% by weight).
In some instances, the dry product may be sub~ected to well-known crushing techniques in order to obtain a granular product for easier handling.
The following examples are illustrative of the present invention but are not to be taken as a limitation on the scope thereof.

;

~0~i336 EXAMPLE I
In these tests a series of tuber starch-urea feed products were prepared in accordance with the invention by in-corporating 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 quanti-ties 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 trademarked HEF
product sold by the Proctor and Gamble Company. The feed consti-tuents were thoroughly admixed in a conventional blender and sub-sequently passed through a Wenger Model X-25 (trademark) extrusion cooker (or in some cases through a Brabender (trademark) 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 inven-tion. The cook temperatures referred to are those measured imme-diately prior to extrusion. The results of this series of tests are summarized in the following Table II:

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~046336 ~ study of the foregoing data will demonstrate that addition of from l to 4~ fat in the starch-NPN admixture synergistically enhances the microbial protein content of the resultant feed product. In particular, addition of fat served ln every case to lower the percent cook value (a measure of starch gelatinization) of the samples, since such 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 ad-versely affected in any appreciable manner by lower cook values, but in fact were 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 cor-rected for the degree of cook (B.P.~% cook). This data clearly demon6trates that although cook values decrease with added lipid, the protein synthesis levelæ derived from the samples are un-expectedly increased. Although not completely understood, it is evident that added lipid synergistically acts with the other feed constituents to achleve the results alluded to above.
In thls connection, it will be understood that rumen fermentation in a live animal is a dynamic process where ammonia ls constantly belng produced, metabollzed, adsorbed or removed.
The concentration of ammonla or mlcroblal protein ln 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 there~ore, not really re-flect increased mlcrobial protein synthesis. In order to ob-viate this factor the in vitro fermentation studies discussed above were undertaken to develop the microbial bacterial protein synthesis data presented. In the in vitro fermentation, ammonia cannot leave the "rumen" by absorptlon or passage and microbial protein cannot leave by passage. Therefore, the ammonia levels .

~Q4~336 and microbial protein levels of the in vitro studies represent an easy method for accurately determining proten 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 pro-cessed feeds hereof containing lipid were much easier to process and handle. Specifically, the added lipid products did not ex-hibit 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:

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.~ ~ ~ ~ ~D u~ ~D ~ ~ u~ I~ ~ ~ ~ ~
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~o _l u~ 0~ 0~ n o~ ~ cr~ O oO ~ u~ ,1 E OD ~ `;t ~ `D ~` ~ ~ ~`I a~ c~i ~

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1` '` '` -' ~ ` co a~ oo co I r~ ~D 00 ~ 1~ X C~l 0~ C`~ ~ ~1 1 _l ~0 ~ _i ~_( _1 cr~ o~ o~ o~ ~D CO
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~ ~ ~ U~ ~ ~ ~ ~ ~ O I~ I~ o~ o ,: :
:~ _1 _1 ~ ~ ~ ~o ~ _1 ~1 ~ ~ ~1 ~ .
i~ ~ : ~

~ O O O O O O O o o o o o ~ ~ ~ U~ ,i C~ ~ 'O ,i ~ o _i ~ ~
~ 'o:
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~o o ~ .~ o o o o ~ ~ a a a la46~36 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 re-sultant feed products. In order to demonstrate the effective-ness of lipid addition in this context, the cook values asso-ciated with each of the runs of this example have been calcu-lated 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 in general 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 protei~ synthesis level notwithstanding the fact that cook values go down with such fat addition. Thus, it is evident that the lipid addition served to synergistically enhance microbial pro-tein synthesis.
Finally, the products of this test were also very easy to cut, dry, handle and store and accordingly are preferred over otherwise identical feeds free of lipid addition.
EXAMPLE III
In thls 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 find-ing that while fat addition lowers cook value, the protein syn-thesis derived from the feed is not adversely affected but rather is increased. Moreover, the resultant feed products are very ~0~t;336 easy to process and in every way represent commercia~y salable feeds, As such, the synergistic nature of lipid addition as herein set forth iB conclusively demonstrated.

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Claims (23)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of producing a palatable, nontoxic ruminant feed product comprising the steps of: admixing a pre-determined quantity of an edible, ungelatinized, starch-bearing food material selected from the group consisting of corn, sorghum, millet, cassava, potatoes, yams, rice, corn starch, potato starch, wheat starch, arrowroot, turnips, rutabagas and mixtures thereof, a sufficient amount of water to permit gelatinization of at least a portion of said material when the latter is subjected to elevated heat and pressure, a quantity of a nonprotein nitro-genous substance characterized by the properties of being hydro-lyzable to ammonia by rumen microorganisms and thereafter being convertible to microbial protein, and an added quantity of a lipid material sufficient to facilitate cooking and processing of said admixture without an appreciable, concomitant decrease in the protein synthesis derivable from the feed product; con-tinuously moving the admixture into and through a treatment zone while agitating the admixture and subjecting the same to a source of heat and high compression and shear forces for a period of time sufficient to gelatinize at least a portion of the food ma-terial in the presence of said water while the food material is intimately intermingled and reacted with the nonprotein nitro-genous substance to provide a reacted composition; and suddenly releasing the pressure on said reacted composition as it con-tinuously leaves the treatment zone to produce an expanded and gelatinized feed product.

2. The method of Claim 1 wherein said nonprotein nitrogenous substance is selected from the group consisting of urea, uric acid, biuret, ethylene urea, ammonium phosphate, ammonium bicarbonate, ammonium carbamate, ammonium citrate, am-monium formate, ammonium acetate, ammonium propionate, ammonium lactate, ammonium succinate, ammonium fumarate, ammonium malate, diammonium phosphate, propionamide, butyramide, formamide, aceta-mide, dicyanodiamide, isobutane diurea, creatinine and creatine.

3. The method of Claim 1 wherein said water is added in an amount such that the total water content of said admixture in said treatment zone is from about 4 to 50% by weight, based upon said predetermined quantity of food material.

4. The method of Claim 3 wherein said water content is from about 10 to 35% by weight.

5. The method of Claim 4 wherein said water content is from about 15 to 25% by weight.

6. The method of Claim 1 wherein said lipid material is added in an amount such that the total lipid material content of said admixture is from about 0.25 to 10% by weight, based upon said predetermined quantity of food material.

7. The method of Claim 6 wherein said lipid material content is from about 0.50 to 6.0% by weight.

8. The method of Claim 7 wherein said lipid material content is from about 0.50 to 4.0% by weight.

9. The method of Claim 1 wherein the temperature of said admixture immediately prior to leaving said treatment zone is from about 220 to 360° F.

10. The method of Claim 9 wherein said temperature level is from about 270 to 340° F.

11 The method of Claim 10 wherein said temperature level is from about 300 to 330° F.

12. The method of Claim 1 wherein said nonprotein nitrogenous substance is added in an amount so that the feed has a protein equivalent level of from about 24 to 125.

13. The method of Claim 12 wherein said protein equiva-lent level is from about 60 to 125.

14. The method of Claim 13 wherein said protein equivalent level is from about 85 to 125.

15. The method of Claim 1 wherein the pressure within said treatment zone is maintained at a level of from about 300 to 500 psi.

16. The method of Claim 1 wherein said lipid material is selected from the group consisting of animal fats, animal greases, vegetable fats, vegetable oils and soybean lecithin.

17. The method of Claim 1 wherein said substance is urea.

18. The method of Claim 1 wherein said lipid material comprises a mixture of animal fat and vegetable fats and is added to said admixture in liquid form.

19. The method of Claim 1 wherein is included the steps of: advancing said admixture through a preconditioning zone prior to introduction thereof into said treatment zone; and introducing into said preconditioning zone a fluid selected from the group con-sisting of steam and water and mixtures thereof for blending with said admixture.

20. The method of Claim 1 including the step of drying said expanded and gelatinized product to a moisture level of less than about 15% by weight, based upon said predetermined quantity of food material.

21. The method of Claim 20 wherein said moisture level is less than about 6% by weight.

22. The method of Claim 1 wherein is included the step of comminuting said expanded and gelatinized product.

23. A palatable, nontoxic ruminant feed product made in accordance with Claim 1.