Method of aiding digestion with artificial roughage materials
United States Patent Salvesen et al.  
 [1 3,876,793 Apr. 8, 1975 METHOD OF AIDING DIGESTION WITH ARTIFICIAL ROUGI-IAGE MATERIALS Exxon Research and Engineering Company, Linden, NJ.  
 Filed: Sept. 25, 1972 Appl. No.: 291,536  
 Related US. Application Data 134,89l, April 16. 197i.  
 Assignee:  
 Division of Ser. No. abandoned.  
 US. Cl 424/83; 424/78 Int. Cl A6lk 27/00 Field of Search 424/78, 83  
 References Cited UNlTED STATES PATENTS III/I968 Collier ll9/l OTHER PUBLICATIONS J. Animal Sci., Vol. 25 (1966), pp. 64-68; Vol. 26, (I967), pp. 849-854; Vol. 28, (1969)), PP. 84-89.  
 Primary E.\&#39;amine&#39;rFrederick E. Waddell Attorney, Agent, or Firm-N. E. Dry; W. T. Clarke [57] ABSTRACT Synthetic polymer compositions such as polymers and copolymers of ethylene and an alpha-olefin having a tensile strength at yield of less than about 1,500 psi, a hardness of less than about 40 units on the Shore D hardness scale, and a tensile strength at 300% elongation of between about 450 to 1,200 psi are effective artificial roughage materials when fed to ruminant animals. These synthetic polymer compositions, when ingcsted by the ruminant, form a loose fibrous mass in the rumen of the animal which enhances rumination. Increasing the rumination results in increasing the consumption of the feed by the animal and thus results in increased production of the animal products.  
 1 Claim, No Drawings METHOD OF AIDING DIGESTION WITH ARTIFICIAL ROUGHAGE MATERIALS FIELD OF THE INVENTION This invention relates to feeding synthetic polymer compositions as an artificial roughage to ruminant animals. More particularly, this invention relates to feeding synthetic polymer compositions having critically defined characteristics to ruminants in order to form a loose, fibrous, hay-like mass in the rumen of the animal. The formation of a loose, fibrous network in the rumen of the animal increases rumination activity and thus maintains animal health during the feeding of high-energy (grain) diets to the animals.  
  The ruminant animal naturally feeds by ingesting relatively large amounts of feed into the rumen with a minimum of mastication before swallowing. One of the characteristics of ruminants is that such animals ruminate; that is, a portion of the contents of the rumen is returned, i.e., regurgitated into the mouth of the animal, for mastication. During mastication, the animal squeezes out the excess liquid and swallows it, then masticates the regurgitated ingesta into the form of a cud. The animal then swallows this remasticated food. Immediately upon swallowing, the act of regurgitation is repeated and new material is returned to the mouth for mastication. This rumination process, which consists essentially of regurgitation, mastication, and return of the masticated material to the rumen, is the natural process by which a ruminant makes a feed more readily digestible. Rumination coupled with ruminal motility which is the mixing of the feed with fluids in the rumen of the animal, aids the animal in obtaining the nutrients contained in the feed.  
  Normally, ruminants are fed natural roughages such as alfalfa or straw hay as a portion of the feed component, along with other high energy feed components such as grain, concentrates, or the like. Roughage is generally considered essential in order to maintain animal health during the feeding of such high-grain diets. One of the major characteristics of roughage is its ability to promote rumination. The physical characteristics of natural roughages vary; however, the essential characteristic of the roughage is that the ruminant must be able to regurgitate the roughage, form a cud, chew the cud, and reswallow the material. While the cud is in the mouth of the animal, the animal must be able to compress and form a bolus of the roughage material and other ingesta, and the bolus should remain compressed such that the ruminant will be able to reorient the cud in its mouth and compress the material continuously. However, when the cud is reintroduced into the rumen of the animal, the material which comprises the cud must be dispersed into particles that can again be regurgitated. As mentioned above, the presence of a sufficient amount of roughage as a feed component is important in order to induce and promote the rumination process, which process if maintained over a long period of time, allows the animal to consume greater quantities of normal feedstuffs. It is readily apparent that increasing the consumption of the feed results in increased production of animal products.  
  However, it has become increasinglydifficult and expensive to provide the large volumes of roughage ,needed, especially in concentrated feedlots where there may be from several thousand to over one hundred thousand cattle in a relatively small area. In addition, the large amount of roughage also produces a large. volume of fecal material which results in pollution and disposal problems. Thus, there are adequate incentives to reduce or eliminate the use of natural roughages and to substitute an artificial roughage therefor.  
 DESCRIPTION OF THE PRIOR ART Various materials have been fed to ruminant animals in order to eliminate the necessity of feeding natural roughage to ruminants. Cracked oyster shell, fed in carefully controlled quantities, is one of the artificial roughage materials which have heretofore been employed. However, there are attendant difficulties with this procedure in that the oyster shell significantly reduces rumination as well as the fact that the oyster shell, which possesses relatively sharp edges and splinters, may damage the animals alimentary canal.  
  Materials such as sawdust, sawdust pellets, newspaper, and other natural and artifical products have been fed to ruminants as a roughage. Plastic materials in the form of polyethylene powder (see J. Animal Sci., 25, 64-68 (1966), P. T. Chandler et al), small pellets (see J. Animal Sci., 21, 277-83 (1962), R. R. Oltjen et al), short fibers (see J. Animal Sci., 28, 84-89 1969), J. A. Boling et al), as well as polypropylene in several different shapes and sizes (see J. Animal Sci, 26, 849-54 (1967), J. G. Welch), have also been fed as artificial roughage with varying degrees of success. These reports indicate some increases in rumination time due to the use of plastic in the diet.  
  It has recently been proposed that inert bodies or pellets of plastic having sufficiently roughened outer surface edges to physiologically trigger secretions of saliva by the animal through physical contact of such roughened surfaces with the wall of the animals rumen when orally administered to the animals may be employed as an artificial roughage material (see U.S. Pat. No. 3,415,225 This artificial roughage material is retained in the stomach of the animal, and as a result of the sufficiently roughened outer edges, results in production of saliva flowing to the rumen. In addition to the effect of accomplishing the stimulation of saliva by physical massage of the rumen walls, the size of the material administered to the ruminants must be selected to minimize mastication of the pellets by the animal in order that the plastic pellet retain a shape capable of effecting necessary massage to the stomach wall. However, while the administering of these plastic pellets has the effect of maintaining or even increasing ruminal motility which is necessary to the health and proper utilization of ingested nutrients, the plastic material does not promote and in fact results in no appreciable tendencies for the animals to ruminate.  
 SUMMARY OF THE INVENTION It has now been discovered that critically defined synthetic polymer compositions, as hereinafter described, when fed to ruminant animals promote the rumination process in that said artificial roughage compositions are regurgitated and chewed by the animal and thereafter formed into a loose, fibrous, hay-like mass in. the rumen of the animal. The loose, fibrous, hay-like mass formed by the feeding of the synthetic polymer compositions provides beneficial functions similar to those provided when the animal is fed natural roughage material.  
  As mentioned above, one of the major characteristics of roughage is its ability to induce rumination. The roughage material, when initially ingested into the rumen, must be dispersed into particles that can be regurgitated. Upon regurgitation, the roughage must then be able to be compressed and form a bolus, i.e., cud of material in the mouth of the animal. In addition, upon continuous mastication of the cud in the mouth of the animal, the material must remain compressed and not disintegerate into a loose particulate mass.  
  Now, in accordance with the instant invention, when ruminant animals are fed synthetic polymer compositions having a tensile strength at yield of less than about 1,500 psi and a tensile strength at 300% elongation of between 450 and 1,200 psi and a hardness of less than about 40 units on the Shore D hardness scale, said compositions are transformed into a thick, loose, fibrous, hay-like network or mass in the rumen of the animal. This hay-like mass can be broken apart by the normal movement of the rumen and the rumen fluid while at the same time it is capable of being regurgitated, rechewed and reswallowed along with some of the other ingesta. In addition, the ingestion of synthetic polymer compositions having the above-described critically defined characteristics results in promoting rumination in the animals such that the animals consume greater quantities of normal feedstuffs when the synthetic polymer compositions of the instant invention are included in the feed fed to the animals.  
  Preferably, the artificial roughage materials of the instant invention are those inert synthetic polymer compositions which exhibit the properties as specified in Table I.  
 TABLE 1 Properties for Polymeric Artificial Roughage Material By tensile strength at yield is meant the tensile stress at the yield point wherein the yield point is the first point on the stress strain curve at which an increase in strain occurs without an increase in stress, as defined in ASTM D 638-64T. This is to be contrasted with tensile strength at break, by which is meant the tensile stress at the moment of rupture of the test specimen, as defined in ASTM D 638-64T. Most preferably, the polymer compositions of the instant invention, i.e.,  
 those polymer compositions exhibiting the physical properties as specified in Table l which act as superior artificial roughage materials in accordance with the instant invention, have a tensile strength at break in the range of from about 2,000 to about 3,200 pounds per square inch.  
  While it is to be understood that any inert polymer composition having a tensile strength at the yield point of less than about 1,500 psi, a 300% modulus of between 450 and 1,200 psi and hardness of less than about 40 units on the Shore D hardness scale will function as an artificial roughage and be beneficial to the ruminant in the above-described manner, the preferred synthetic polymer compositions amenable to the instant invention can be generally classified as an elastomeric polymer wherein the polymer, copolymer, or blends thereof conform to the specification as described in Table 1. Representative, nonlimiting examples of elastomeric polymers which can be employed in the practice of this invention include: styrene butadiene elastomers, ethylene vinylacetate polybutadiene elastomers, ethylene-propylene copolymers, ethylenepropylene terpolymers wherein the third monomer may be 1,5-hexadiene, dicyclopentadiene, S-ethylidene norbornene, isobutylene-isoprene copolymer, polyisoprene, polychloroprene and the like. The most preferred elastomeric polymer compositions of the instant invention comprise a copolymer of ethylene and an alpha-olefin and most specifically an ethylene-propylene copolymer wherein the content of ethylene is in the range from about to about weight and wherein the content of propylene is in the range of 10 to about 20 weight Plastomeric polymers, by which is meant a polymer which is made of the same monomers as an elastomeric polymer but due to polymerization conditions exhibits a plastic quality to the elastomer, which can be employed in the practice of the instant invention include: ethylene-propylene copolymers wherein the ethylene content is in the range of from about 80 to about 90 weight While it can be generally stated that plastic materials alone, such as polyethylene, polypropylene, polystyrenes and the like, exhibit a hardness which renders such materials outside the scope of the instant invention, blends of plastic-elastomeric polymers which exhibit the specifications as defined in Table l are particularly preferred artificial roughage materials. Typical, nonlimiting examples of such plastic-elastomeric blends include: polyethylene-elastomer blends wherein the elastomere consists of ethylene-propylene copolymers, ethylene-propylene-terpolymers and the like.  
 The most preferred plastic-elastomeric polymer blends,  
 in accordance with the instant invention, comprise from about 25 to about 75 weight low density polyethylene in combination with from about 75 to about 25 weight of an ethylene-propylene copolymer or an ethylene-propylene-S-ethylidene norbornene terpolymer and mixtures comprising equal weight percentages of said ethylene-propylene copolymer and etheylenepropylene-S-etheylidene norbornene.  
  It will be obvious to one skilled in the art of polymer formulation that materials useful for this invention can be made from mixtures of a polymer with other components such as plasticizers, fillers, and other polymers, or could be altered by vulcanization or physical working, etc. Thus a polymer which does not inherently meet the specifications of the instant invention could be formulated with other materials to produce a material which does conform to the required specification.  
  While not wishing to be bound by any particular theory, it is believed that synthetic polymer compositions having the above-described critical characteristics, i.e.,  
 tensile strength and Shore hardness, result in unexpectedly superior artificial roughages in that said compositions, while in the rumen, form a loose, fibrous hay-like mass, which floats in the rumen while at the same time forms a bolus of material which can be compressed when masticated in the mouth of the animal and thereby aids digestion in the rumen by promoting salivation of the animal.  
  If synthetic polymer compositions having a tensile strength at yield and at 300% elongation below about 500 psi, i.e., low density polyethylenes, are employed cubic inch or about 0.032 cc. in volume) were found to be effective, but tend to pass from the rumen more rapidly compared to the larger particles and thus would be less desirable.  
  For example, an artificial roughage material consisting of an ethylene propylene copolymer, i.e., 83 to 90% ethylene and 10 to 17% propylene having a tensile strength at yield of 650 psi, a tensile strength at 300% elongation of 725 and a hardness of 30 on the Shore D hardness scale, was fed to fistulated cattle in the shapes and sizes indicated in Table II, and examination of the TABLE H Size and Shape of Particles Fed Formed Loose Rate of Passage Shape Length Width Thickness Interwoven Mass Through Rumen Oval H2&#34; H2&#34; H4&#34; Yes Slow Rod I/2&#34; I/4&#34; Yes Slow Random /l6-l/&#34;&#39;&#34; l/l6-l/4&#34; l/8&#34; Yes Rapid Shredded l/2-l 3/8-5/8 l/4-l/2 Yes Slow Flat l/2-3/4&#34; l/Z&#34; l/lo-l/tl Yes Slow as an artificial roughage material, the roughages material is chewed into smaller and smaller pieces and eventually eliminated from the animal. The latter type of material is not capable of forming a bolus and does not function like natural roughage. Polymer compositions with a tensile strength above about 1,500 psi, i.e., crystalline polypropylene, result in a roughage which is too difficult to be chewed by the ruminant and will not allow the formation of a hay-like mass in the rumen of the animal. Such compositions may also be expected to cause irritations of the intestinal tract. Polymer compositions which have a hardness above about 40 on the Shore D scale will tend to irritate the lining of the intestinal tract. The synthetic polymer compositions within the limits of tensile strength and hardness as described in Table l are critical in order that the artificial roughage material can be chewed and transformed into thin, fibrous strands which are soft and pliable, and which will eventually form a loose, interwoven mass in the rumen.  
  Thus, it can be seen that the synthetic polymer compositions of the instant invention offer significant advances over that presently available in the art in that said compositions maintain ruminal movements, stimulate the more worthwhile rumination activities, which reduces the adverse effects such as bloat during the feeding of high-energy rations to the animals.  
  The physical shape of the polymer which may be fed to the ruminant animal is not critical for formation of the fibrous, hay-like mass and may consist of rods, tubes, spheres, thin flakes, cubes or other convenient shapes. The particles may have smooth or rough surfaces. Particle size is of some concern and should be small enough to be readily accepted by the animal. With beef and dairy cattle weighing over 500 pounds, particles of about 1 inch in length, about one-half inch in width and about one-half inch in thickness (0.25 cubic inches or about 4 cc. in volume) are acceptable. Particles longer than 1 inch with the above thickness and width tend to be less readily consumed. However, if the larger particles are ingested by the animal, they are masticated and found to be effective. Thus, there is a practical limit to the size which should be fed. Small particles of less than one-fourth inch in length and oneeighth inch in width and one-sixteenth inch (0.002  
  Ruminant animals can subsist on natural roughage alone, but ruminant animals fed for commercial production of meat or milk are usually fed rations containing about 5 to 50 weight natural roughage material. The remainder of the ration provides the nutrients and energy required to provide commercial levels of production. The non-roughage portion, called the high energy portion or concentrate, is composed of cereal grains (corn, soybean, etc.), oilseed meals (e.g., soybean meal), or other protein sources, urea, vitamins, minerals and other supplements. In accordance with the instant invention, the ruminant animal feed composition may contain from about to about 99.99 weight concentrate having admixed therewith about 0.01 to about 5.0 weight concentrate having admixed therewith about 0.01 to about 5.0 weight of the synthetic polymer compositions of the instant invention, and more preferably from about 0.05 to about 2.0 weight In view of the fact that the artificial roughage materials of the instant invention promote rumination, the amount of said materials as synthetic polymer compositions which may be added to the feed may vary over a wide range in order to achieve the desired result. For example, larger quantities of the synthetic polymer compositions of the instant invention may be fed to animals consuming large quantities of high-energy, readily digested rations (high grain rations). Lesser quantities may be desirable when fed to animals consuming relatively low-energy, less readily digestible rations, as, for example, rations which contain some natural roughage components. Accordingly, it is to be understood that it is clearly within the scope of this invention to feed the artificial roughage materials of the instant invention in conjunction with natural roughage material to aid in the digestion processes of the ruminant animal. It can be seen that the promotion of the rumination activity of the animal is essential in order to achieve either or both of these end results.  
  Having now described this invention, further illustrations are shown in the following examples. However, no limitations are to be implied from these examples over and above those contained in the claims appended hereto, since variations and modifications will be obvious to those skilled in the art.  
  Table Ill shows the effect of employing a variety of synthetic polymer compositions having a density of be- 5 tween 0.70 and 0.99. The performance of these compositions in the rumen in Runs 8-17 were observed one to two hours after the feeding through a window in EXAMPLE 1 TABLE 111 Properties of Various Polymeric Materials and Comments on their Ability to he Regurgitated and Formed into a Mass in the Rumen Performance in Ruminant Polymer Physical Properties forms Tensile Yield 3007: Polymer Hay-like Run Polymer Material Hardness Strength at Strength Modulus Regurgi- Mass in Nov Type Composition Rating Scale Break.psi psi psi tated Rumen Remarks 1 Polyesters 94- Rock- 8.000- 2.000- 8.000-  
  120 Well M 20.000 10.000 20.000 2 Acrylic 100% Methyl- 80- 7.000- 6.000-  
  Resins methaerylate 105 1 1.000 10.000 3 Nylons 100% Polyamide M3 1- 5.120- 5.000- 5.000 Due to the hardness of the R120 14.000 12.000 12.000 composition. while the ma- 4 Poly- 100% Polystyrene M65- 1.500- 1.500- terial would he regurgita- Styrenes R100 12.000 10.000 ted. a hay-like mass would not he expected to he 5 Poly- 10071 Polypropylene 70 Shore 4.900 3.000- formed in the rumen.  
 propylene D 4.500  
 (1 High 100% Polyethylene 60-70 3.100- 2.000-  
 Density 5.500 5.500 Polyethylene 7 Melamine 100V: Melamine -65 3.500- 1.500 3.000-  
 Formaldehyde Formaldehyde 5.500 5.000 Resins Resin 8 Polyethylene 1009 Low Density 4X 1.600 1.600 1.350 Yes No Composition as polyethylene broken down into small pieces by mastication. No interwoven mass formed.  
 9 Polyethylene 57% Low Density 35 1.500 950 910 Yes Yes Particles elongated Elastomer Polyethylene 43% by mastication and Blend Copolymer (containing tended to form a 72-76% Ethylene. small mass. 14-189 Propylene and 3-3.40? -Ethy1idene Norhornene) 10 Ethylene 81-83); Ethylene; 2.750 650 800 Yes Yes Elongated fiber-like \&#39;inylaeetate 17-19% \&#34;inylacetate particles formed by Copolymer mastication which 11 Polyethylene 3392 Low Density 33 2.030 700 780 Yes Yes form a large. loosely Elastomer Polyethylene 33&#39; hound interwoven Blend Copolymer (containing mass in the rumen.  
 72-765? Ethylene. 14-1891 Propylene. 3-3.49; S-Ethylidene Norhornenel 336i (opolymer (containing 83-909; Ethylene. 10-17% Propylene) l2 Polyethylene 62% Low Density 32 1.650 770 700 Yes Yes Particles elongated Elastomer Polyethylene 3371 by mastication and Blend C opolymer (containing tend to form a small -469? Ethylene. mass. 54-609? Propylene) l3 Ethylene 83-90% Ethylene. 30 3.150 650 725 Yes Yes Elongated fiber-like Propylene 10-1752 Propylene particles formed by Copolymer mastication which form a large loosely hound interwoven mass in the rumen. l4 Polyethylene 509? Low Density 30 1.500 720 Yes Yes Particles elongated Elastonier Polyethylene 506} by mastication and Blend Copolymer (containing tend to form a small 72-769? Ethylene. mass. 14-18% Propylene. 3-3.3491 S-Ethylidene Norhornene) 15 Polyethylene 435: Low Density 30 1.450 550 620 Yes Yes Particles elongated Elastonier Polyethylene 57% by mastication and Blend Copolymer (containing tend to form a small 72-76% Ethylene. 14-1854 Propylene. 3-3.495 S-Ethylidene Norhornene 1 TABLE Ill Continued Properties of Various Polymeric Materials and Comments on their Ability to be Rcgurgitatcd and Formed into a Mass in the Rumen Performance in Ruminant Polymer Physical Properties forms Tensile Yield 300% Polymer Hay-like Run Polymer Material Hardness Strength at Strength Modulus Regurgi- Mass in No. Type Composition Rating Scale Break.psi psi psi tated Ru&#39;men Remarks 16 Polyethylene Low Density 1.400 400 450 Yes Yes Particles elongated Elastomer Polyethylene 75% by mastication and Blend C opolymer (containing tend to form a small 72-76% Ethylene. mass. 14-18% Propylene. 34.492 5 Ethylidcne Norborncne l7 Ethylene 72-76% Ethylene. 2) 1.350 220 280 Yes No Particles were Propylene 14-18% Propylene. broken down into Copolymer 3-3.-l&#39;/ 5-Ethylidcne small pieces by Norbornene mastication. no mass formed.  
 TABLE IV Average Daily Feed Intake. Pounds/Head Animals Fed Arti- Test Period Control Animals l&#39;lcial Roughage Difference lst month 24.4 25.6 1.1 2nd month 255 26.5 1.0 3rd month 24.5 27.2 2.7 4th month 23.) 25.8 1.9 Total Fccd lntakc During Entirc Test Period of 126 Days. Pounds/Head 3094 3303 209 This table shows that synthetic polymer compositions EXAMPLE 2 This example shows the increase in feed consumption resulting from the use of the artificial roughage material of the instant invention.  
  Two groups of ten animals each were fed a ration consisting of 15% ground com, 78% ground sorghum grain, 5% soybean meal, 0.5% urea, 1.0% dicalcium phosphate, 0.5% trace mineralized salt and 2000 IU per pound of vitamin A. This ration was fed twice daily and all animals were permitted to eat all the grain they would consume. Water was available to the animals at all times. One group of animals was fed the above ration and the other group the same ration plus 0.75 weight of an artificial roughage material of the instant invention; namely, an ethylene-propylene copolymer containing 83-90% ethylene and 10-17% propylene, per 100 pounds of ration. The test was run for a period of 4 months in a finishing program and the animals were fed both rations up until the time of slaughter. The average daily intake for each month and the total feeding period are listed below in Table IV.  
 In addition to a substantial increase in feed consumption by the ruminants feed the artificial roughage material of the instant invention, examination of the digestive tract of both groups of animals indicated severe deterioration of the rumen papillae of the control animals, but little or no deterioration of the papillae in the animals receiving the artificial roughage material. Accordingly, this shows that the artificial roughage material was acting as a natural roughage material by maintaining the papillae in a healthy condition. Other parts of the digestive tract such as the abomasum and small intestines on the control animals had damage ranging from slight to severe, whereas the animals fed the artificial roughage had little or no injuries to these organs. The damage to the small intestines of the control animals was a reddening of the intestinal wall, attributed to acidosis which is prevalent with animals fed a lowroughage diet.  
 What is claimed is:  
  l. A method for aiding digestion in a ruminant animal which comprises feeding to said ruminant animal in conjunction with an animal feed an effective rumination promoting amount of an inert, elastomeric, ethylene propylene copolymer of 83 to weight percent ethylene and 10 to 17 weight percent propylene, said copolymer having a tensile strength at yield of between about 400 to about 1,500 pounds per square inch, a hardness of less than 40 on the Shore D hardness scale and a tensile strength at 300% elongation of between about 450 to about 1,200 pounds per square inch.