It has been known for some time that digestion of proteinaceous feed in the rumen reduces the potential feeding value of such feed, because the amount of protein available for uptake by the animal, and available to. for example, add bulk to beef cattle, or produce milk in dairy cattle. is thereby reduced. Protein remaining after animal feed passes through the rumen is termed"rumen undegraded protein."or RUP. Each feed has a typical rumen undegraded protein value ("RUPV"), that is, the amount of undegraded protein that remains after it passes through the rumen. Without efforts to enhance the RUPV, the RUPV of meat and bone meal, for example, is approximately 47%, that of blood meal is 65% and that of fish meal is 60%. Vegetable proteinaceous feed has an even lower RUPV, with, for example, soybean meal having an RUPV of approximately 25-30%. By enhancing the RUPV of feed, such that a higher percentage of its protein is available for post-rumen digestion, the feed is thereby improved.

Efforts to enhance the RUPV of proteinaceous feed by protecting the protein of animal feed from rumen digestion began in the late 1970s. with research into the use of chemical treatment with tannins (U. S. Patent No. 3,507,662) and formaldehyde (U. S.

Patent No. 3,619,200) to protect proteins. Tannins, however, can render the protein unavailable in the abomasum, and formaldehyde is not approved for use in animal feeds by the Food and Drug Administration.

Meyer discloses several means of protecting protein by mixing zinc salt with meal, with and without heat: U. S. Patent No. 4,664,905 discloses the addition of zinc salt with sufficient moisture to form an aqueous solution of zinc salt; U. S. Patent No.

4,664,917 discloses the mixture of dry zinc salt with dry meal; U. S. Patent No. 4, 704, 287 discloses the pelleting of meal mixed with zinc salt after steam conditioning; and U. S.

Patent No. 4,737,365 discloses feeding dairy and beef cattle with dry-blended feed with

zinc oxide and zinc carbonate. Other prior references of interest are cited in these patents.

U. S. Patent Nos. 4,957,748 and 4,957,748 disclose the heat treatment of feed under defined pH and percent moisture conditions with reducing sugars, such as xylose, glucose, fructose, lactose, mannose, ribose, hemicellulose, and spent sulfite liquor. U. S.

Patent No. 5,064.665 discloses heating proteinaceous feed with reducing sugar under conditions sufficient to cause early Maillard reactions, but not advanced Maillard reactions.

U. S. Patent No. 5, 496,572 discloses the protein protection of feed by mixture of a calcium or magnesium compound with proteinaceous feed and one or more fatty acids in a liquid form. and heating the mixture to induce a reaction between the fatty acid (s) and the calcium or magnesium compound.

Metals have been added to animal feed as supplements. U. S. Patent Nos.

4,994,284 and 4.888,185 discloses fluid supplements containing up to 5% magnesium oxide and 2-10% calcium phosphate. U. S. Patent Nos. 5,260,089,3,794,740 and 5,068,114 also disclose the use of magnesium oxide in solid or block feed supplements, and U. S. Patent Nos. 4,800,088,4,729,896,4,160,041, Re. 31,763 (reissue of 4,171,385), Re. 31, 804 (reissue of 4171, 386), 4,265,916,4,234.608, and 4, 996, 065 include magnesium oxide in solid animal feed and feed supplements as a solidifying agent.

SUMMARY OF THE INVENTION The present invention provides a method of enhancing the RUPV of any proteinaceous meal, by subjecting the meal to pressure in the presence of an added RUPV enhancing effective amount of a ruminant-edible constituent, and enhancing the RUPV of animal meal, by subjecting the meal to pressure, or to heat in the presence of an added RUPV enhancing effective amount of a ruminant-edible constituent, all so as to obtain a proteinaceous feed composition.

Preferably, the pressure used in the methods of the invention is between about 20 psi and about 60 psi, measured as gauge pressure. More preferably, the pressure is between about 30 psi and about 45 psi, and in a preferred embodiment, the pressure is about 30 psi.

Preferably, the pressure is applied to the proteinaceous meal for about 5 to about 30 minutes. More preferably, the pressure is applied for about 10 to about 20 minutes, and in a preferred embodiment, the pressure is applied for about 20 minutes.

In a preferred embodiment, the pressure used to obtain the proteinaceous feed composition is steam pressure. Preferably, the steam is at a temperature sufficient to pasteurize the meal. More preferably, the steam is at a temperature to sterilize the meal.

In another preferred embodiment, the approximate protein content of the proteinaceous meal is known. Preferably, the added RUPV effective enhancing amount of a ruminant-edible constituent is present in an amount such that the ratio of the constituent to the protein content of the proteinaceous meal is about 0.1 mmole/g to about 2.0 mmole/g. More preferably, the ratio is about 0.1 mmole/g to about 0.5 mmole/g.

In yet another preferred embodiment, the approximate fat and approximate moisture content of the proteinaceous meal are known. Preferably, moisture is added to the meal before it is subjected to pressure such that total of the fat and moisture contents is about 18% to about 20%.

In yet another preferred embodiment, the ruminant-edible constituent added to the animal meal before it is subjected to pressure is selected from the group comprising calcium, zinc, manganese and magnesium.

In yet another preferred embodiment, the ruminant-edible constituent added to the animal meal before it is subjected to heat is selected from the group comprising calcium, manganese and magnesium.

In yet another preferred embodiment, the ruminant-edible constituent added to the proteinaceous meal is magnesium. Preferably, the magnesium is in the form of magnesium oxide. More preferably, the magnesium oxide is a lightburned technical grade in a powdered form.

In yet another preferred embodiment, the proteinaceous meal is heated at about 82EC to about 160EC. Preferably, the meal is heated at about 104EC.

In yet another preferred embodiment, the proteinaceous meal is heated for about 10 seconds to about 20 minutes. Preferably, the meal is heated for about 10 minutes.

In yet another preferred embodiment, the proteinaceous meal subjected to pressure or heat is animal meal. In a preferred embodiment, the animal meal is meat and bone meal. In another preferred embodiment, the animal meal is blood meal. In yet another preferred embodiment, the animal meal is fish meal. In yet another preferred embodiment, the animal meal is poultry by-product meal.

In yet another preferred embodiment, the proteinaceous meal subjected to pressure in the presence of an added RUPV enhancing amount of a constituent is vegetable meal. Preferably, the vegetable meal is soybean meal.

The present invention also includes a method of feeding ruminants by feeding ruminants with the proteinaceous feed composition prepared according to the disclosed methods. In a preferred embodiment, the feed composition is formed into pellets before feeding to ruminants. In another preferred embodiment, the feed composition is formed into blocks. In yet another preferred embodiment, the composition is dried.

The present invention also includes the proteinaceous feed composition prepared according to the disclosed methods.

BRIEF DESCRIPTION OF THE DRAWINGS The Figure is a diagrammatic representation of an embodiment of an apparatus used to practice the invention.

DETAILED DESCRIPTION The present invention relates to. among other things, methods of producing and feeding to ruminants a proteinaceous feed composition with enhanced protection from protein digestion in the rumen. An object of the invention is to increase the rumen undegraded protein value ("RUPV") of the feed and thereby to improve the commercial value of the feed and of the ruminants which consume the feed.

The methods of the invention, as described further below, can be variously used with all types of protein-containing, i. e., proteinaceous, feed existing as a meal, including meals containing animal protein, microbiological protein and vegetable protein, or any combination thereof. For example, all methods can be used with microbiological meal, such as meal composed of yeast cells, or bacterial cells resulting from fermentation.

Some methods can be used with animal meals such meat meal. meat and bone meal, blood meal, fish meal, poultry by-product meal, or any combination thereof. Further, some methods can be used with vegetable meals, such as soybean meal, cottonseed meal, peanut meal, sunflower meal, rapeseed meal, palm kernel meal. or any other protein seed meals or mixtures thereof.

The methods of the invention include adding an RUPV enhancing effective amount of a ruminant-edible constituent to the proteinaceous meal and subjecting the meal and added constituent to pressure or heat to obtain a proteinaceous feed composition. An"RUPV enhancing effective amount"of the constituent is an amount that increases the RUPV enhancement using a method of the present invention.

A"ruminant-edible constituent"should be understood as a constituent which can be consumed by a ruminant in the amounts described in the invention without adverse consequences to the ruminant. It should be understood that the"constituent"refers to an atomic element which is part of a mineral, oxide or salt (for salts not generally referred to as minerals) of the class of elements which tend to form divalent cations; for example, calcium, zinc, manganese, magnesium. and the like. While the precise mechanism by which the subjection of meal to pressure or heat in the presence of added elements which tend to form divalent cations enhances the RUPV of the meal is unknown, without limiting the invention to any particular theory, it is believed that the treatment acts to stabilize existing weak polar bonds which maintain the three-dimensional structure of the protein in the meal, and/or to facilitate the formation of additional such bonds, perhaps by the formation of divalent cations by the added element and the formation of weak polar bonds between the cations and the protein, such that the protein is less subject to degradation and loss of its three dimensional structure in the rumen. It should be understood that a combination of added ruminant-edible constituents may be used to create an RUPV enhancing effective amount.

The constituent can be added to the meal in liquid or solid form, for example as a chloride, oxide, or sulfate of an element. In a preferred embodiment, as discussed further below, the element is magnesium. Most preferably, magnesium is added in the form of MgO. MgO is available from Martin Marietta Magnesia Specialties (Hunt Valley, Maryland) in a variety of grades, including lightburned grades in powdered or granulated

form, hardburned grades in kiln run, milled or screened sizes, and deadburned periclase grades as briquettes, or screened or milled fractions. Preferably, a lightburned grade is used, most preferably, MagChem40, a lightburned, technical grade magnesium oxide which is sold by Martin Marietta as a powder. MagChem40 has the following typical composition and physical properties and specifications: Chart 1 COMPOSITION Tvpical Specifications Magnesium oxide (MgO), % 98. 2 97. 0min. ignited basis Calcium oxide (CaO), 0. 8 1. 0 max. Silica (Si) 2), % 0. 35 0.5 max. Iron oxide (Fe203), % 0. 15 0.3 max. Aluminum Oxide (A1203), % 0. 10 0.2 max. Chloride (Cl), % 0. 30 0.5 max. Sulfate (S03), % 0. 05 0.3 max. Loss on ignition, % 23 3. 0 max. PHYSICAL Bulk, density, loose, 22 (0.35) PROPERTIES lb/ft3 (g/cm3) Mean particle size, microns 5 3-8 Surface area, m2/g 45 40-60 Activity index, seconds 9 7-11 Screen size, % passing 99.5 99.0 min. 325 mesh, wet

It will be understood that subjecting the proteinaceous meal to"pressure"means subjecting the proteinaceous meal to a pressure substantially greater than normal atmospheric pressure at sea level (about 14. 7 psi). By substantially greater. it is meant applying an additional pressure of at least about 20 psi greater than atmospheric pressure.

Preferably a RUPV enhancing effective amount of pressure is applied, meaning an amount effective in combination with the temperature of the meal and/or, if used. the divalent cation forming element, to increase the RUPV of the treated meal to obtain a proteinaceous feed composition. It should be understood that the proteinaceous meal subjected to a RUPV enhancing effective amount of pressure can be any type of proteinaceous meal.

In a preferred embodiment, the meal is subjected to gauge pressure between about 20 psi and about 60 psi. As known to those skilled in the art,"gauge pressure"refers to the

pressure measured on a pressure gauge, which is the pressure above atmospheric pressure.

Therefore, for example, about 20 psi gauge pressure refers to about 34.7 psi absolute pressure. More preferably, the meal is subjected to gauge pressure between about 30 psi and about 45 psi, and even more preferably, the meal is subjected to about 30 psi of gauge pressure.

In another preferred embodiment, the proteinaceous meal is subjected to pressure for about 5 to about 30 minutes. Preferably, the meal is subjected to pressure for about 10 to about 20 minutes, and more preferably, the meal is subjected to pressure for about 20 minutes.

In yet another preferred embodiment, the pressure is created by steam. Preferably, the steam is at a temperature sufficient to pasteurize the meal. A further object of the invention is a pasteurized proteinaceous feed composition. As is known to one skilled in the art, temperatures sufficient to pasteurize are temperatures about 66EC. More preferably, the steam is at a temperature sufficient to sterilize the meal. A further object of the invention is a sterilized feed composition. As is know to one skilled in the art, temperatures sufficient to sterilize are temperatures between about 125EC and about 150EC, preferably about 133EC.

Preferably, if an ruminant-edible constituent is added to the meal before subjection to pressure, the constituent is either calcium, zinc, manganese or magnesium, or combinations thereof, and most preferably, the element is magnesium.

The present invention also provides a method of enhancing the RUPV of proteinaceous meal by heating the meal in the presence of an added RUPV enhancing effective amount of a ruminant-edible constituent other than zinc, wherein the proteinaceous meal is animal meal or microbiological meal. Preferably, the constituent is calcium, manganese or magnesium, or combinations thereof, and more preferably magnesium.

It will be further understood that subjecting the proteinaceous meal to"heat"or "temperature"means that preferably a RUPV enhancing effective amount of heat is applied, meaning an amount effective in combination with the pressure, and the added constituent, to increase the RUPV of the treated meal so as to obtain a proteinaceous feed composition.

In a preferred embodiment, the meal is heated at about 82EC to about 160EC.

Preferably, the meal is heated at about 104EC.

In another preferred embodiment, the meal is heated for about 10 seconds to about 20 minutes. Preferably, the meal is heated for about 10 minutes.

The present invention also includes a method of enhancing the RUPV of proteinaceous meal by subjecting the meal to pressure, wherein the meal is animal meal or microbiological meal, so as to obtain a proteinaceous feed composition.

Further, it is preferable that if the meal is subjected to either heat or pressure, moisture is added such that the sum of the percentage of moisture present in the meal and the percentage of fat in the meal is about 15% to about 30%, and most preferably, about 18% to about 20%. Typically, moisture content is estimated using procedures accepted by the Association of Official Analytical Chemists (AOAC), as published in Official Methods of Analysis, currently in its fifteenth edition (1991). Fat content is estimated based on procedures measuring ether extract content, also as accepted by the AOAC. Estimates can also be based on historical data regarding fat and moisture content of meal from the same plant, microbiological or animal source.

In a preferred embodiment, in those methods of the invention which included an added constituent, the ratio of the molar amount of the element to the weight amount of protein in the treated material is from about 0.5 mmole/g to about 3.0 mmole/g, more preferably, from about 0.1 mmole/g to about 2.0 mmole/g, and yet more preferably 0.1 mmole/g to about 0.5 mmole/g. In this regard, it should be noted that typically the protein content is estimated from nitrogen analyses or from historical data based on protein- containing meal from the same plant. microbiological or animal source. These estimates are nonetheless accurate enough to provide guidance in selecting an amount of a constituent for use in the operation of the invention.

The present invention also encompasses methods of feeding ruminants feed with enhanced RUPV. In various embodiments of the invention, the proteinaceous feed composition obtained by the methods of the invention can be fed to ruminants in pelleted form, in block form, or in dried form.

The following examples further illustrate the present invention but are not intended in any way to limit its scope.

Example 1 This example illustrates the general procedure used in pressure treating meal in a steam pressure cooker 1, such as that illustrated in the Figure. One such pressure cooker suitable for use in the invention is that manufactured by ANCO-EAGLIN Inc., which has a working load volume of about 75 cubic feet (Greensboro, North Carolina). The power drive

2 was turned on to begin rotation of the cooker. The meal was loaded into the interior of the rotating cooker I through the loading dome 3. The dome lid (not shown) was closed. All vent values (not shown) were closed. The steam inlet 4 was opened to allow steam into the shell, and internal steam was added to the cooker 1. The cooker 1 was heated to about 270EF and about 30 psi, as measured by the pressure gauge (not shown). The internal steam was turned on and off as necessary to maintain 30 psi for twenty minutes. Fluctuations of the internal temperature occurred during this period. After twenty minutes. all steam to the cooker I was shut off and the pressure was released slowly through a vent line (not shown) to the atmosphere through an adjustable valve (not shown). The cooker was unloaded through the discharge door 5. The treated meal was slightly darkened in color.

Example 2 This example illustrates the use of several embodiments of the invention to enhance the RUPV of meat and bone meal, by the use of pressure, and pressure in the presence of a ruminant-edible constituent. An amount of meat and bone meal (MBM) sufficient to perform all runs described in this example was collected from a rendering plant in a ground and cooled state. For each of the thirteen runs listed in Chart 2, fifty pounds of the MBM was placed into a Hobart mixer (Troy, Ohio). For each separate run, the specified amount of added constituent listed in Chart 2, if any, was added, and the constituent-meal combination, or the meal alone, was mixed for 12 minutes. A few grams of each batch (of for example0. 5kg) was removed and measured for protein content using nitrogen analysis. as described in Association of Official Analytical Chemists, Official Methods of Analvsis (15th ed., 1991). For each run, the remaining constituent-meal combination, or meal alone, was pressurized at the pressure listed in Chart 2 for 20 minutes in a pressurized steam cooker manufactured by ANCO-EAGLIN, Inc. (Greensboro, North Carolina). Samples were taken of each run after pressure treatment, and the RUPV measured by the ammonia technique as described in Herold et al., Evaluation of Animal Byproducts for Escape Protein Supplementation, 1996 Nebraska Beef Report, pp. 26-28. See Chart 2: Chart 2 Added Run Constituent Pressure (psi) Protein, % RUPV, % 1 none none 49.7 53. 0 2 none 30 53.4 68.8 3 1. 5% ZnSO4 30 52.3 71.0 4 0.75% ZnSO4, 30 51.5 69.4 1.0%MgO 5 10% MgO 30 54.1 69.6 6 none 45 52.8 56.8 7 1.5% ZnSO4 45 48.6 60.9 8 0.75% ZnSO4, 45 52.8 60.4 1.0%MgO 9 1.0% MgO 45 51.4 61.4 10 none 60 50.2 57.2 11 1.5% ZnSO4 60 49.7 59.9 12 0.75% ZnSO4 60 48.8 60.3 1. 0% MgO 13 1.0% MgO 60 48. 9 59.7

Example 3 This example illustrates the use of several embodiments of the invention to enhance the RUPV of meat and bone meal by the use of heat treatment in the presence of a ruminant-edible constituent other than zinc. An amount of meat and bone meal (MBM) sufficient to perform all runs described in this example is collected from a rendering plant in a ground and cooled state. For each of the three runs listed in Chart 3, fifty pounds of the MBM is placed into a Hobart mixer (Troy, Ohio). For each separate run, the specified amount of added constituent listed in Chart 3, if any, is added, and the constituent-meal combination, or meal alone, is mixed for 12 minutes. A portion of each batch is removed and measured for protein content using nitrogen analysis. For each run, the remaining constituent-meal mixture, or meal alone, is heated for 20 minutes at the

temperature listed in Chart 3 in a non-pressurized steam cooker manufactured by ANCO- EAGLIN, Inc. (Greensboro, North Carolina). A sample is taken of each mixture after heating, and the RUPV measured by the ammonia technique as described in Herold, et al., Evaluation of Animal Byproducts for Escape Protein Supplementation, 1996 Nebraska Beef Report, pp. 26-28.

Chart 3 Run Added Constituent Heat EC none Room Temperature 2 none 104 I 1 1. 0% MgO104

While this invention has been described with an emphasis upon preferred embodiments, it will be obvious to those of ordinary skill in the art that variations in the preferred compositions and methods may be used and that it is intended that the invention may be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications encompassed within the spirit and scope of the invention as defined by the following claims.