CA1330651C - Method and product for promoting improved meat quality in meat producing animals - Google Patents

Abstract

Abstract Method and Product for Promoting Improved Meat Quality in Meat Producing Animals The growth rate of meat-producing animals as well as the yield and quality of the meat obtained therefrom is improved by administering to the animal prior to its sexual maturation an effective amount of a female gonadal steroidal compound; namely, an estrogen or progestagen compound and preferably a mixture thereof, sufficient to delay development of the gonadal function of the animal, e.g. spermatogenesis.
Such administration is terminated sufficiently prior to slaughter of the animal that the administered steroidal compound has been substantially completely removed from the animal's system which before slaughter exhibits levels of the corresponding natural hormones therein substantially within normal limits. In mammals, administration is preferably by injection, but in fish, shellfish and poultry, the active steroidal compound is incorporated at low levels in the usual feed therefor. In mammals, the treatment is preferably applied to uncastrated males but can be extended to females and castrated males if desired; while in fish, shellfish and poultry administration is without regard to sex. The ratio of lean meat to fat is increased significantly by the treatment and in male mammals aggressiveness and odor development with consequential tainting of the meat is suppressed until slaughter.
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Description

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` , .t ~ Technical Field .. This invention relates to a method of produclng a growth promoting material for administration to animals and to a method of promoting the growth and increasing the food conversion efficiency of meat-producing animals in general and improving the quality of meat obtained therefrom and is concerned more particularly with the administration to a meat-producing .
animal, such a~ pig~, cattle, fi~h ~nd th~ like, of at least one female gonadal ~t~oidal hormone prior to its j~ 10 sexual maturatio~, and pr~fexably at an early ~tate of its ^i growth, so as to retard th~ sexual de~elopment o~ the animal while 6imultaneow ly promoting it~ growth to a ~urprising degr~o.
Backqround Art ~3 It ha~ lonq b~n de~ired to increa~e the rate of ~ growth in meat-producing animal~ as well as to enhance the ¦ quality of the meat deri~ed ther~fsom, e~pecially a~
regards the proportion of l~an to fat in ~uch meat.
Progress has, of cous~e, be~n made to thi~ end by the hybridization of variou~ mæat producing animal~ and in formulating proved ~c~d compo~itions with a view to achieYing an incrca~e ~n the rat~ of growth o~ the animal and the efficiency of th~ convor~ion of it~ ~eed, i.e., the ratio of unit w~qht of mea~ produced per unit quantity of feed con~u~d, but little hope appear~ to exi~t for further major progr~a~ along the~Q line~.
Another lonq-recognized approach adopted for male meat-producing mammal~ ca~t~ation of animal~
usually at an ~arly at~ge ~n th~is d~velopment for the ,~
purpose of achieving a ~ind of ~minization of the male :~
~ animal while simultanflou~ly sliminating it~ normal ¦ agg~es~ive behavior and aexual activity. More recently, ~ castration has been co~bined with hoxmone adminiatration I typically accomplish~d by a continuous releaae hormonal ~ implant inserted, for instance, in the ear of the i castrated anL~al at an age typically of 2-3 months. The ~. . . .

2 1 ~0651 the quantity of the hormone aad the rate of its ~elease from ~he implant, as detenmined by the composition of the implant, are so de~igned a~ to achieve a gradual and continual relea~e o~ the hormone into the animal'~ ~ystem and so correlated with the rate of metaboli~m of the hor~one in the animal'~ ~ystem that th~ quantity of hormone remain-ing in the ultimate meat obtained after 61aughter was sufficiently ~mall as to ~ati~fy applicable govexnment ~tandards. While ca~tration alone or combined with a hormone implant has ~oma beneficial consequence~ on the ultimate meat pro~uction in term~ o~ increa~ed weight pro-duction and thu~ b~tter f~ed eficiency, much of the improvement i6 in the ~o~m of increased fat, e.g., a higher ratio of fat to lean which, of cour~e, oSf~et6 the overall improvement by reduced m~at quality.
Con~iderable research has ~een done by the pre~ent applicant~, their associates, and others in the field of hormone~ in o~r to acquire a better understand-ing o~ th~ ~normously complex changes that are 9 nvolved 20 in hormone secretion $n ~n~mals and th~ effects o~ such secretion in various ani~al ~p~cies. Ext~n~ive studies have been ~pplied to such animals ~uch as fish, chicken, pig and xuminant~ ~uch as deer. ~hus, it ha~
been described how th~ ~d~nohypophyseal cell~ of teleo~t fi~h, chicken, rats and pig8 respond to gonadal ~teroid~
administered during embryogene~i~, the neonatal or ~criticalU
period, the adùlt stage, and during old age. This r~search was done by V. R. Pantlc ln ~Synthe~i~ and Release of Adenohypophy~eal ~ormone~, Plenum Pres~, N. Y. 1980 (~. Jutisz and X. W. ~cXern~, ed~.) pp. 335-362. Gonado-tropic cells that secrete FS~ and LH were found to be suppre~sed, while prolact~ and growth stimulating cell8 were increased. Th~ ef~ec~ we~e moct pronounced during embryogenesis and the neonatal critical period. ~hese studies were continued, w$th th~ emphasi~ on prolactin target cells, by V. ~. Pantlc, ln ~Regulation of Target Cell Recpons~veness~, Vol 2, Pl~um P~e~3, N.Y. 1984 ~X. W.
McXerns, A. Aak~aag a~d V. ~anc~on, eds.) pp 283-295.

~ `~ 3 1 3~0651 Further, it ha~ been shown by F. C. Bancroft, PO ~. Dobner and Li-Yuan Yu, in ~Synthesi~ and Relea~e of Adenohypophyaeal ~or-mones~, Plenum Press, N.Y. 1980 (N. Jutisz and X. W. McKerns, eds.) pp. 311-333;tha~ glucocorticoids induce pregrowth hor-mone messenger RNA. A description ha~ been provided how prolactin, ~rowth ho~mone, and chorionic somatomammotropin are derived from a common evolutionary ancester protein. ~11 are lactogen$c and growth promoting~ W. L. Miller and S. W.
MRllon, in ~Regulation o~ G~ne Expression, Plenum Pres~, N.Y.
1983 tK. W. McX~rn~, ed.) pp. 177-202. Du~ing evolutton the genes for these horm~ne~ migrated to ffeparate cell type~ and are under complex regulatory processes.
The complexity of hormonal effects and the diffi-culty of predicting the consequences of the samq is illU8-trated by the differ~nt and even opposite effects that are often obtained according to the amount and the duration of the admini~tration of a given hormone as well a~ the period of such administration in the development of the animal. For example, a low-level con~tant admini~tration may continually suppres~ a particular function1 a single highe~ ~oes may initially ~upp~ess that fun¢tion, followed by a rebound increase. ~he suppre~s~on of adrenal cortex ~ecretion by estrogen, followed by a ~a~ked rebound increa e in adrenal ~-glucocorticoid secretion ha~ been described by X. W. McXe~ns in ~The Regulation of Adre~al Funct$on by Estrogen~ and Other Ho~mones~, Biochemica Et Biophy~ica Acta, 71 ~1963) 710-718. ~-~
From the information obtained dur~ng studies ~uch as the above as well as 6u~aguent unpublished re~earch, .
it has been discovered, quite remarkably, that the admini~
tration of a female gonadal ~teroidal ho ne to meat pro-ducing animals if applied to the ~nimal before it~ sexual i~
maturation, and pref~rably qu$te early, espec$ally dur$ng its neonatal period, a ~u~pri~ing and entirely unexpected selective response i~ induced by which the ~exual matu~ation of the animal, e.g., achiev~ment of thc gonadal functlon such a~ spermatogenesis in m~les ~nd development of aecondary sex characteristic~ uppre~ed or retarded while the growth function and anabolic effect of the animal i8 enhanced and 1 3~0651 made more efficien~. Those knowledgeable in endocrinologyhave traditionally b~lieved that sexual maturation, e.g., spermatogene~is in the male, the developmen~ of secondary sexual charac~e~istics, including the development of the seminal glandular sy~tem of the animal, and relea~e of andro-gen and growth hormone prolactin cQmplex to achieve a growtb-ana~olic effect in male animals occurred together in the na~ural maturation of the anim~l. Thus, castration would obviously prevent sperma~ogengsi~ and the development of o secondaxy sexual characteri~tics but with a consequent~al reduction in the relea~e of androgen and its anaboli~ effect and the growth ho ne-prolactin effect 80 that growth pro-duction was channeled more toward fat rather than muscle or lean meat.
In the practice of the pre~ent inv~ntion, an unexpected and surprisingly selective or differential response has been fcund, by which ~pe~matogensis and secondary sexual development are temporarily ~uppressed or blocked whlle simul-taneously androgen and growth hormone-prolactin production, a~ manifested, ~or exa~ple, by the level of the male gonadal hormone testosterone ig not only not suppressed but remains at least comparable to, ~ ~ot high~r than, that taking place in similar untreat~d a~imal~. AB a con~equence, the anLmal can be brought to its normal slaughter weight at a time si~nificantly e~rli~ t~an i~ required for untreated or intact an;mals or castrated animals. The conversion of the feed by the an~mal dur$ng tb~ growth period up to slaughter, j which is its st rapid growth period, takes place at a I significantly more efficient rate, as measured in terms of unit weight of meat der$ved per unit weight of feed cosumed.
Purther, the proportion of fat i~ reduced ~o that a leaner meat product having a higher ~atio of lean to fat is obtained giving a ~ignificantly h~gher meat guality. ~he characteristics of the meat ~n other xe~pect~ such B~ flavor, tenderness, texture and ~o on do not appear to be adversely affected by the practice of tbe present method and remain at leas~ as acceptable as, ~f not bett~r than, those of meat obtained from untreated animal8, ~cluding castrates.

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: 1 33065 1 Additional ~enefit~ have al~o been observed in ~om~
species notably the pig, Sexual maturation in the male pig occurs, on the average, at around five months and i8 mani-fested by aggre~sive behavior and sexual activity such as fighting with other males and attempted mounting~. AS the secondary sexual characteri~tics become fully developed, the seminal sy~tem becomes operative re~ulting in the strong odor characteri~tic of boars and this strongly oderiferous s~minal fluid permeates the tissue of the animal causing it~ meat to be tainted for most human consumption. Male pigs treated according to the pre6ent invention do not exhiblt such agg~essive behavior and are free from the obnox~ous scent and meat flavor of untreated male pigs.
The reality o~ the improvements described above has been theoretically con~irmed by histological testing of the treated animals compared with untreated animals. ~hus, the present invention has been shown to lead to induction, proliferation and increased gene expression of growth and prolactin cells in the pituitary that secrete growth hormone, growth factors and prolact~n hormone. Prolactin has both a growth stimulating effeot and a gonad suppressing effect.
Pituitary gonadotrophs * at secrete ~olicle stlmulating hormones tFHS) and luteinizing hormones (L~) appear to be suppressed in number and functicn. The pro-opioid-corticotropin cells appear to be increased. Increased endor- :
phins (and other opioid cQmpounds) from these cells may have a sedative-tranguilizing e~fect on the animals. Increased corticotropi" ~CT~) enlarge~ the vascular and reticular zone oS the adrenal cortex and increases glucocorticoid and androgen production.
More specifically, ta~ing the pig a~ an example, it was observed hi6tologically by th~ light micro~cope and the electron micro~cope that growth hormone and prolactin cell types in the pig pitu~tary were increa~ed, as were cell~ -that ~ecrete pro-ACT~-endorph~n. On the other hand, gonado-tropin cell~ that ~ecrete FS~ and LH were decrea~ed.

~isclosure of the Invention The invention in one aspect comprehends the method of producing an injectible growth promoting material for non-implantative administration to non-ruminant animals comprising heating an injectible oil vehicle, adding an estrogen hormone material to the vehicle, adding a progestagen hormone material to the vehicle and dispersing the hormone materials in the vehicle, the estrogen and progestagen hormone materials being effective at the proportions added, when administered to an animal at dosage levels, to temporarily increase substantially the level of each such hormone material in the animal and to delay its sexual maturation, without impairing its primary sexual development, until after the time of slaughter without unacceptable residual amounts of either of the hormone materials in the slaughtered animal.
The invention also comprehends a method of preparing a non-ruminant animal feed product containing an edible growth promoting hormone preparation comprising preparing a basal ration for the animals and adding an edible oil to the basal ration, the edible oil containing at least one of a female gonadal steroidal hormone, the level of hormone being effective, when the treated ration is fed to animals at about the neonatal period of development, to substantially increase the level of such hormone in the animal and to delay its sexual maturation, without impairing its primary sexual development, and to generally delay its sexual maturation until after slaughter without producing an unacceptable residual amount of the hormone in the slaughtered animal.
The invention also comprehends the growth promoting material and the animal feed product whenever prepared by the above processes or their obvious chemical equivalents.
The invention also comprehends the use of a compound comprising a combination of an estrogen-and a progestagen steroidal compound in which the weight of the progestagen compound exceeds that of the estrogen compound, for treating sexually intact meat-producing domestic non-ruminant animals for market, to improve the yield and increase the proportion of lean to fat meat obtained therefrom when the animal is slaughtered after achieving a marketable body weight. The compound is adapted to be non-implantatively administered to the animal to be treated at a time during substantially its neonatal stage of development in at least one dosage in an amount which is sufficient to produce in the animal an 1 33065~

essentially immediate, temporary suhstantial increase in the level of each of the steroidal compounds in the animal's system, the temporary increase persisting for a period that is short in duration relative to the time interval between the ¦ time of such administration and the date of slaughter, such dosage being effective to delay sexual maturation of the animal ¦ so that sexual maturation does not occur prior to the date of slaughter of the animal without substantially impairing its sexual development and growth function. The animal is at least substantially free of any residual amount of the thus-administered stero~dal compounds at the date o~ slaughter.

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;,....~, i Broadly, in the invention, an effective amount of at least one female gonadal ~teroidal compound, l.e., o~ the steroidal estrogen and proge~tagen type~, is administe~ed to meat producing animals, such as pig~, cattle, fish and other species, before the sexual maturation of the animal, and preferably at an early, and opt~mally very early, ~tage in its development, ~uch adminiatration in amount and duration being sufficient to repress the gonadal function of the animal during a signi~icant portion of Its growth ~eriod and being terminated ~o that the administered steroidal compounds are at least ~u~tantially eliminated by the natural metabollc action of tbe animal prior to its slaughter 80 that the resultant meat i~ essentlally f~ee o~ add0d hoxmones and withi~ th~ acceptable limit~ for sa~e human consumption or as imposed by government regulation.
More specifically, it i8 preferred that a mixture of a steroidal e~trogen compound and a steroidal progestagen compound be administered in which the progestagen compound considerably predominates. Such a proportionation conform~
generally to the levels of these hormones occurring naturally in mammals as well as those recognized safe for administra-tion to humans for other purposes, for example, birth control.
An optimum ratio ha~ been ~ound to be approximately 5sl but other ratios including equality and even an excess of the estrogen compound are possible within the broad scope o~ the invention. A factoral design useful in dete~mining fiuitable dosage combinations for thls mixtu~e of female steroidal hormones appears below a~ ~able 1;
Table 1. Factoral De~ign to Establish Optimal Do8e Combination for Pig~
Progesterone (mq) ~ . ~ __ . r . .
_ 0 l25 250 500_ ~ __25 125 250 500 01 .. . ~ .. . ..
O 5o-~ l25 250 S00 lO0 125 250. 500 ~.

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~` 7 1 ~3065 1 In principle, all cGmbinations within the design of ~able 1 are useful, exclusive of the 0/0 combination~ e.g., 1/1-1/20.
Moreover, within the broad scope of the invention, either an estrogen type ho~mone or a progestagen type l st~roidal honmon~ can ba administe~ed exclusively, although a combination of the two $~ much pr~r~d and has been found to give significantly more u82~ul ben~ficial effects in the treated animals. Where a singlG hormone of these types i8 selected, the levels of aA~inistration thereof should be o substantially increa~ed, say at least dou~led, over the amounts of the correspoAd~ng compound ~n the preferred ~` compound in the pr~f~rr~d combination. Although full studies have not been carried out up to now, it ~8 beli~ved that progestagen will give a ~tronger effect over an estrogen type compound and would hance b~ preferred if only a single compound is ~mployed~
It will b~ understood that the t~rms steroidal ~ estrogen and steroidal proge~tagen eacb refer to groups of w~ closely related compound~, tber~ having now been developed '~ 20 a great variety of ~peclfic compounds or derivative~ witbin ~ both of these group~, as can bs identified with any of the `~ variously available pharmacological handbook~. Certain of the~e compounds are produced naturally in the animal and are available as extractants from natural source~. As natural compounds, they are u~ually accepted as ~afe for administra-tion to animals and human~, w~thin rea~onable limits, without the necessity for any ~p~cial approval by governmental agencies, e.g., the Food and Drug Administration, and such natural cQmpounds are s~mewhat preferred for thi~ reason.
Thus, a preferred e~t~og~n steroidal hormone is ~stradiol, ~ preferably in the form of one o~ it~ pharmacologically I acceptable ester~, such as the dip~opionate,and hydroxy-progesterone, preferably in the fo~m Of one of lt~ pharma-cologically acceptable este~ uch as the caproate are among the most preferred compound~.
Many oth~ e~trogen~c and prog~stagenlc hormone~
are in principle appl~¢able i~ the practlce of thi~ in~entlon and broadly spsaking, any 0~ 0~ the~e cateqories og ho ne~

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i~, 1 ~3065 1 that have been established to have an estrogenlc or proges-tagenic function so as to be useful, fox example, in hormone therapy in humans or ~nimals can be employed here from those which are already o~ subsequently become available in the pharmaceutical fi~ld. In other words, the present invention re~ides in the applicat$on of hormones known in themselves, for a 6pecific and extraordinary function rather than in the deY~lopment and ~erf~ction of new kind~ o~
specific hormcnes.
Ths various ava$1ab1a 2strogeA and progestagen compounds can be read~ly ~d~nt$fied from pharmaceutical hand-books and other text~, and referencs may be had to these source~ for guidance ln selec~ing a speci~ic compound or mixture of compound~ to be adm$n~stex~d $n accordance w$th this invention. ~he natural e~trogens, ~.e., estradiol, estrone and estriol, are identif$ed in Merck'~ Index together with the variou~ com~only ~nown derivat$ves thereof, a particularly lengthy li~t of derivatives appearing $n the 8th edition, 1968, of th$~ tsxt. Mo~t of these deri~atiYes are mono- or polyestsrs of va~$ous organ$c acids, of which the 3-benzoate and th~ dip~opionate of estradiol are especially preferred. Other form~ of the~e compounds such as their salts are also known and pharmaceutically acceptable salts where availabl~ and accepted for hormone therapy are useful in principle. An additional tabulation of estrogens and progestagens appea~s $n the text EssentialQ of Medicinal Chemistry by Xorolkovas ~ Burckhalter, John ~lley & Sons, copyright 1976, in Table 40.3 (pages 629-631) and 40.4 (pages 633-635). A further tabulation containing mainly ~ynthetic progestagens can be found in the ~andbook of Chemistry and Physics, 1975-76 ~dition at pages C-756-759.
More cQmplete information a~ to the variety, ~ature, properties and effects of specific members of these two groups of hormones can be ound in more specialized text~, and inasmuch as re~ort can b~ had to this material for ~ ;
additional information, fu~th~r elaboration as to the specific compou~d8 u~eful he~e 18 unnece~ary.

~ 9 -- 1 33065 1 As is generally known and accepted, the various specific compound~ that are avai~able for purpo~e~ of this invention are generally similar in charact~ri~tic~ and behaviox, differing mai~ly ~n the speclfic rate at which they are metabol$zed by the ~y~tem of the animal and elLminated therefrom as well a~ in theix rate of ab~orption by the body and theix stability. Ihese minor variation~
are o~ little or no con~equence as regards the overall performance of these oo~pound~ in thi~ invention.
It is well known that ~teroidal hoxmones in general are readily metabolized by th~ animalls system so that any excess over the natural l~vel of the hormone in the animals (and both male and fe~ale eaoh ha~e significant measurable levels o~ both e~trogen and progo~texone ~ype hormones a~
well as testo~tero~e) iB removed within 24-48 hour~. The administration of the female gonadal bormone here mu~t continue over a suf~icie~t period of time during the develop-ment of the animal a~ to inhibit or retard lts ~exual matur-ation until a~ter ~laughter, say 30 dsy~ or ~o, ~lthough longer and somewhat ~horter time~ could be utilized if desired. The application of multiple do~age~ of the ~terold compound during thi~ pexiod i~ a workable approach but may not alway6 be convenient. A pre~rred mode o~ admini~tration to mammal~ i the hypodermic injection of the hormone in an acceptable carrier or other ~oxm which retards the release of the hormone into the animal 1 8 system. ~he preferred compounds designated above hav~ little solubility in water but are ~uf~iciently soluble or di~p~rsable in oil vehiclas as are con~entional and typically u~ed ~or phanmacolog$cal compositions designed for injection, o~ wh~ch vegetable oil~, ~uch as olive oil, ar~ preferable, although other pharma-cologically use~ul oil ~ehicle~ ~hould be acceptable in principle, ~he combination o~ the oil vehicle and the hormone ccmbine~ to achieve a ~uf~iciently slow release o~
the hormone into the animal'~ ~y~tem for present purpo~es coveri~g a period of con~id~rable day3 and even up to about 30 day~ e~pecially if the injection i8 accomplished sub-dermally to produce a pock~t o~ the hormone in oily vehicle `- lO 1 330651 immediately below the ~kin of the animal which is gradually absorbed. Intramu~cular injection is also pos~ible but usually entails an increa~ed rate o~ absorption a~ is known.
The amount o~ the mixture ~n~ected may vary but a few ml, say 2 ml, is ordinarily sufficient, depending of course on the concentration of the hormone.
In many instances, a single dosage at an effective level of the female gonadal hormone will suffice in the present practice; however, as mentioned, multiple dosages may lo be utilized especially for larger animals, or multiple dosages at reduced levels at int~rvals of ~everal days, perhaps 2-3 days to 7 days, or longer in ~om~ cases, could be substituted if preferable. The ~ite of the injection can be varied to suit an individual preference but the inguinal region or groin has been found entirely sati~actory in the case of pig8.
Derivatives of the stRroidal hormones ~n quest~on have been produced which exhib$t increased water 801ubility I and especially ~o~ such com~ounds, oral admini~tration i~
an alternative route o~ admini~txation, and in any case, oral administration i8 necessary fo~ some food producing ~pecies, ~ such as fish and ~hell~ish that obviously cannot be inoculated ¦ on any practical basi~. Alternatively, since eve~ the poo~ly water coluble ~te~oidal hormon~ usually have ~ome ~mall degree of water solubility, tAe am4unt of the admini~tered compound could be increased 80 as to achieve a level of ass~milated hormone that i~ con3istent with the active level~
described above, the unab~orbed exce~ o~ the honmone simply beinq eliminated th~ouqh ~h~ animal's digestive tract.
Where oral admini~tration i~ desired o~ necessary, the hormone can be incorporat~d in the feed of the anim31 specie~ at a very low level, say a fraction of a perce~t, e.g. 0.5, up to 1-2~ by weight, as to be con~i~tent with thorough mixing and safe application by avoiding pocket~ ox localized areas o~ exces~ively concentrated materlal. ~hu~, food pellets containing the bormone or pellatized hormoneR
mixed with a qreatly predominan~ amount of granular feed could be used, being made available to the animal during the administration period ~or a period oi ~ome days, dependent ;l '.

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- : -` 11 1 33065 1 upon the particular species being treated. Alternatively, most mammalian species, especially cattle and sheep are ordinarily given so-called feed supplements containing enhanced levels of protein, minerals, vitam~ns and the li~e and small levels o~ the active hormone could be incorporated into such supplements, being made availa~le to the animals separately from their standard feed. In this fashion so~ewhat better control over the uptake of the hormone by individual animals can be exercised than if the active hormone is applied via the general feed mixture.
There are also now available hormons derivatives in which an estrogen function and a progestagen function are cQmbined into the molecule of a single compound. Standardized test6 have been developcd fox measuring the effective level of these respective function~ and such measured effective levels can be equated with the effective quantity of the individual hormones of a combination for purposes of adminis-tration. That is to say, if such a ~composite~ compound should exhibit comparable functional activity for each of the estrogen and proge~tagen functions corresponding to the relative proportions of the separate estrogen and progestagen compounds referred to above, then such a combined compound could be substituted in entirety. Alternatively, if the estrogen function or the progestagen function of a combined compound were less or greater as the case may be, than the desired relative proport~ons a~ determined for the separate compounds, then such a composite compound could be supple-mented with the amount of additional estrogen or progestagen compound as needed to achieve the desired relationship of the two hormone functions.
As indicated above, inasmuch as an essential resul~
of the present concept i~ the suppression of the sexual maturation of the animal, the a~inistration must obviou-cly be initiated before sexual maturation has taken place.
Although, broadly speaking, sexual maturation is a gradual lengthy process, its culmination in the sen~e of the capacity to produce young either as a male or female i~ for a given animal, as in humans, a fairly well defined event in time, although the point in time of that event will vary consider-12 ~' 1 33065 1 ably between individual animals o~ the same species. Fullsexual maturation can b~ identified scientifically by histological examination under, for example, an electron microscope of the brain cells and neuron~ of the animal to ascertain whether or not fully matu~e cell diferentiation in critical areas of th~ brain, notably th~ pituitary, has already occurred. A more empirical but nonetheless useful standard can be followed ba~ed on cQmmon expexience and observation of the animals in ~uestion inasmuch as sexual maturity is, as already mRntioned, typically manife~ted by readily perceptible sexual activity and aggres~ive behavior especially on the part of male~ cluding fighting and attempted mountingR. This u~ually occurs in the pig at around q-5 month~, and thu~ administration in thi~ invention should be begun well ~efore that time.
The clo~er the administration i8 begun to the point of full sexual maturation, the less the improvement that can be achieved by the practice o~ this method. Consequently, administration i8 ~trongly pre~erred to be initiated quite early and in any case long prior to full brain cell differ-entiation and sexual maturation. By beginning early in the life of the animal, brain cell differentiation in the critical areas of sexual development and growth are at a minimum and thus the remarkable e~fects o~ the present concept on brain cell development are maximized. The optimal timing for mammals is during their so-called neonatal period, that is during the few days following their birth. In the pig, the I neonatal period corresponds to days 1-7 after birth and ¦ administration during thi~ period appears to be ideal for 1 30 purposes of this invention. Indeed, administration at day 1 for pigs i8 particularly preferred since this i8 the normal occasion for castration of male piglets in the practice o~
the age-old castration technique, for the admini~tration of ¦ iron and/or other injection~, and ~or the clipping of the ¦ needle teeth of the piglet~ 60 as to minimize nur6ing i discomfort to the brood 80W8. Thus, a single injection on day 1-3 of the admini~te~d hormone, e.g., a mixture of a natural e~radiol hormono ~d ~ proge~terono compound in the " 13 ~ 1 330651 proportions described above, say 50 and 250 mg, respectively, in a vegetable oil vehicle, has been itself to give eminently satisfactory results in achieving the objects of the present invention. If preferred, a second dose at equal or reduced levels could be added at about day 7 particularly if the initial dose were reduced accordingly The injection of the just identified mixture in xix-week old piglets, however, still induced Leydig cell (testi~) hyperplasia and hypertrophy with a nine-fold increase in 6~rum testosterone, indicating the inducement of a marked anabolic effect in these piglets, although administration at this time was less effective in increasing prolactin-growth hormone~
! As will be ob~erved from later data, the very rapid weight gain that occurs in mammal8 during their initial growth phase, e.g., in piglet8 Up until about day 120 follow-ing a single injection at day 1-3, ~alls rapidly and in order to sustain an increased weight gain after this time, an ¦ additional injection prior to the end of this period, e.g.
~ prior to day 100 for pig8, should prove advantageous, subject 1 20 to the re~uirement that the added hormone be eliminated from ~ the animal's system su~ficiently early prior to slaughter.
¦ The levels of administration of the female steroidal hormone do not appear critical and can vary considerably.
While the hormones in question presumably have toxic limits like virtually all other mRdicinal compounds, such limits if they are known are far graater than even the maximum levels that need be applied in this invention, and toxicity thus is not a matter of concern here.
An evaluation of the appropriate level of adminis-tration can be carried out scientifically by histological scrutiny of the brain cells of the animals being treated compared with compa~able untreated animals for the actual detection of si~nificant alterations in the rate of develop-ment of the sexually-related cell functions in the brain.
However, a less rigorous but practically useful evaluation is possible by a simple obse~vation of the animals since when the female hormone i~ being applied at an acceptable leYel, the male anLmals exhibi~ a small but perceptible s '' ~

~ 14 1 33065 1 amount of nippl~ enlarg~ment or ~walling. ~ence, if such swelling or enlargem~nt i~ taking place, this indicates administr.~tion of the hor~o~e at an effective level. Obvious-ly, gross or mas~ive nipple and breast enlargement in the treated male animal~ 18 ~ot de~irable and in the unlikely event that such were ob~ervsd, the levels of hormones being administered would be deemed to be excessively high and should be reduced in ~utu~e t~eatments.
In the case of pi~, administration o~ a mixture of an estradiol and progesterone in amount4'of 25 and 125 ~g, respectively, du~ing the neonatal period was ~ound to be somewhat less effective than tho pre~erred dosage level~ of 50 and 250 mg. On th~ oth~x ha~d, i~ the p~efe~s~d do~age level~ are doub~ed, e.g., to 100 ~nd 500 mg, respect~vely, the results were found to be ~llghtly better when adm~niRtered during the neonatal perlod than the preferred dosage but not proportionately better and not ~ufficiently better in view of the doubled dosage o~ the ho nes.
When the horm4ne mixture is administered in an oily vehicle, the level~ in th~ blood of the admini~tered hormones, ~ starting from an elevated l~vel upon injection, drop gradually until at the 28-30 day age, where injection takes place on the first or second day, th~ levela have decreased to the normal blood levels for the hormones in question in the animal.
Inasmuch as the animal i~ normally slaugh~red well after thi~
time, slaugher in the ca~e of pig8 occurring when the pig reaches a weight of about 100-110 kg ~or about 2~0-240 pound~) which is reached when th~ pig is about 5-6 months old, this natural clearing e~ect o~ the honmone from the animal's system means that the hormo~e i8 completely elimlnated well before slaughter. Elim~nation of the administered hormone, i.e., the excess above normal blood levsl~, not later than 60 days prior to slaugh~er i~ considered entirely sa~e, although it i~ b~ d that ~lim~nation not later than 30 days prior to ~laughter will prove e~ually ~afe and acceptable. Given the~e ~cceptable time limitations, the administration can obviou~ly continue pa~t the one month period in pigs, ~or ~xample, up to the point where clearance . , - ` 15 -' 1 330651 occurs at the appointed time prior to ~laughter. Although the ~sual pharmacologically-inert carriers are entirelv suitable, specialized measures could be adopted for achieving a sustained relea~e of th~ active hormone if preferred.
Inert polymeric matricea, such as that sold under the trade-name "Silastic~ by ~ow Chamical have been developed for this kind of release and could be utilized here along with similar developments.
Compared to untreated intact animals and untreated lo castrated animals, the treated animals are found to be bigger and longer in si~e, the proportion of lean meat to fat has been significantly increased, slaughter weight is achieved within a significantly shortened period of time, e.g., about 15-20 days in the case of pig~, and the efficiency of the animal's conversion of the feed as expressed in terms of unit weight of meat product per unit weight of feed consumed is significantly increas~d. Due to the significant acceleration of the feeding cycle, wh~reby the pig, for example, reaches a market weight of about 100 kg in about 165-170 days, compared to a~out 185 day~ for both intact and castrated pigs, the overall production cycle at a mass production facility can be definitely greater.
Up to now, no adverse effects have been noticed in the practice of the invention. Although spermatogenesis is inhibited as is the development of secondary sexual character-istics beyond the normal slaugh~er t~me, if the male animal~
should not be slaughter~d, they eventually exhibit normal sexual development and actiYity although at a somewhat later time than untreated animals. The method of the invention does not cause any ultimate defosmity or diminution in the sexual function of the animal, t~st$cular development being normal with only spermatoqenesis being temporarily delayed.
While the present ~ethod is aimed primarily in the ~ case of mammals at the male animal, some modest potential ;~ exists for extending its improvement to ~emale animals. ~he desirability or bene~it o~ administration to females is inherently les~ than in the case of males ina~much as the me~t of ~e~ule ~ uls i9 already more deslrablo a~d ,, .

~1 ` ` .

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` 16 ~ 1 33065 1 preferred than is the m~at of males. ~he achievement of a~y androgen effect~ in fem41~s i~ not possible by the present method although ~ome improvement in the growth hormone e~fect should be realizable pe~hap~ at about 5-10~ bett~r growth rate than the untreated ~emales. Simiiarly, some improvement in the lean meat to ~at ~atio would be expected. The timing of the administration and other conditions would follow along as for the males.

Hormone implants on castrated animals are employed with cattle which are normally castrated at three months or so and the continuous release has a strong feminizing effect distinct from the growth stimulation of the invention.

In the ca~e of cattle, the neonatal period extends from day 1 through about day 21 and administration preferably takes place during this period and ideally quite early in this period, say day 1 o~ day 2 as with pigs, although delays beyond this date are readily po~sible. The level of adminis-tration for larger anima18 doe~ not increase proportionately with increasing body w~ight of the animal at the time of administration, although ~om~ increase in the absolute amount or the administered hormone i8 indicated for larger animals.
~hus, for a new born calf weiqhing about 36 kg, the level o~
the administered ho n~ ~hould perhaps be twice that employed for new born piglet~ w~ghing about 1.1-1.2 kg, and the duration of administratlon for cattle ~hould be around about two month~ or so but can continue longer in view o~ the con-siderably greater age of cattle ~or ~laughter. Thus, beef cattle are normally 81au~htered at an age greater than one year, say about 14 months, a~d the maximum conceivable dura-tion of administration i8 ~ucb a~ to be cleared from the animal's sy~tem about 30-60 day~ prior to slaughter. The latest time for admini~tration to cattle would be at around four months of slaughter, but earlier is much better.

.. . . .

-:- 17 ~' ' 1 33065 1 Multiple dosages might be more convenient wi~h cattle, say three dosages, one at the preferred level of the mixture on day 1 or ~ and the next a~ a total of say 300 mg approximately two weeks later, and a third at 1-2 months of age at the 300 mg level. In addition to ord~.nary bee~ cattle, veal and so-called "baby beef~ can likewise be treated.
The principle o~ the invention is applicable to fish and shellfish, and the results of the practice of the inven-~ion are in some re~pects eveA more extraordinary for fish than ~or mammals. Fi~h at birth or hatching ars not sexually differentiated in contrast to mammals where. the sex of a given animal can be readily discerned at birth (sexual differ-entiation of ma~mals generally occurring during gestation).
Similarly, fish have a considerably less highly devel,oped brain and endocrine Ry~tem than do mammals at the time of bir~h so that the entirety of the hatch of young ~ish can respond to the present metbod without the male/female differ-ences noted above in mammals. In fact, wherea~ f$sh event-ually develop into male~ and females at about a 50:50 ratio under normal growing conditions, treatment of the fish by the present invention cause~ a ~ubstantial shift toward the development of females to give a mals to female ratio of about 20-30:80-70. The d~proportionate increase in the ratio of female fish is advantageous aince female fish have better growth characteristics tha~ m~les. It is notable al~o that the invention re~ults in an increased number of herma-phrodite and sterile fi~h which is advantageou~ ~rom the standpoint of meat product,ion since it avoids the energy consumed by the sexual cycle, i.e., for egg production, whiGh is considered wasted for pur~06es of meat production. The sexual maturation of the ~ish is likewi~e delayed so that they reach marketable w~ight earlier and can be harvested before breeding takes place.
Newly hatched fingerlings are born with an attached yolk sac which i~ consumed by the fingerlings during about the first 3-4 month~ of their ~xistence dependent upon such factors as water temperature and amount of available light so that the fingerling~ do not actually begin feedi~g in the sense of consuming externally ~upplied food until 3-4 months of age. Obviously, the hormone of the invention cannot be administered to ~ish until a~ter they have begun to feed and preferably the admini~tration iR begun at their first feeding.
The hormone is supplied to the fish via their food~
being incorporated into the usual food pellet~ or granules at a level of about 0.5-2.0~ by weight. ~he feeding can be extended for about 5-7 days and longer if desired, but 5-7 lo days has been ~ound ent~rely ~uf~icient and further adminis-tration of the hormone seems to produce no corresponding increase. While the rate o~ growth for ~ish i~ affected by external conditions such as water temperature and the amount of available light, in general ~ish such as rainbow trout are ready to be harvested and marketed at about one and one-half years age counting an initial three months period for assimilation of the yolk sac, or say about one to one and one-quarter years after the first feeding. By this time the administered hormone is fully cleared from the fish's system.
20 ~he period of administration can, therefore, certainly be extended safely but availability of the hormone at the usual feeding intervals during the ~irst wee~ to two weeks after first feeding of the fish has been found entirely sufficient to produce significantly desirable results. Excess or over-feeding of the hormone~containing feed should be avoided during this period.
Although the mixture of an estrogen compound and a progestagen compound as preerred for mammals can li~ewise be utilized in the caae o~ fish, it is preferred for the ~ 30 latter to administer an e~trogen compound alone, selected 53 from those available to the art. The inclu~ion of any pro-gestagen compound does not appear to cignificantly influence I the response of fish to the present methodO Both cold and warm water fish respond to the $nvention, including saLmon, rainbow trout, carp and others currently being cultivated.
The invention iB also de~med to be applicable to various shellfish including ~hrimp, lobster, crayfish, oyster~, mussels snd the like, and ln general, the treatment would . , .

`- 9 - 1330651 follow the same pattern or the~a specie~ as for ~ish, the hormone being admin~ste~ed early in the feeding cycle of the species via the feed that i~ supplied thereto ~sllowing principles that are now well developed ~or the forming of such specie~.
Turning now to poultry, chicks are di~ferentiated sexually at birth and havs a higher level of brain and endocrine development than do fish, but nevertheless, the present method will have be~eficial e~ects on both male and female chickens. The hatch tlme for chicken eggs is approxi-mately 30 days, and while it is technically possible to inject the chicken embryo with the hormone within the egg, this practice is contraindicated her~ due to the potential for causing increased abnormalitie~ in the chicks after hatching.
The hormone is applied to chic~ens via their ~eed being incorporated into the ~eed at a level of say about 0.5-2~
by weight. Inasmuch as chickens are already bred to maximize feed efficiency, the effect of the invention on chickens is not anticipated to be as high as for mammals, fish and the like. The response of chickens more closely parallels that of mammals than fish in that the invention causes no altera-tion in the normal male/female ratio. A mixture of an estrogen and a proge8tagen compound is preferred for adminis-tration to poultry but e8tro~en alone could be substituted with less beneficial r98ult~. Poultry, of course, includes turkeys, Cornish game h~ns and other commercially produced fowl, such as ducks, geese and guinea fowl.
Example I
150 male pigl~t~ o a strain of Swedi~h Landrace were divided into group~ o~ 50 and were eithe~ castrated, left intact or given a single injection with the compound mixture under the skin in the scrotal area during the neonatal period, specifically on day 1 or 2 after birth. The injected dosage contained 50 mg of estradiol dipropionate and 250 mg of progesterone caproate, i.e., 17-hydroxyprogesterone caproate, dissolved or dispersed in olive oil as a vehicle or carrier as described in Example VI. Prior to weaning, the animals were given a pre-weaning feed, and after weaning a post-weaning .
- --- t330651 feed, followed by a growth and finally a fini6hing feed, all feed mixtures being regular formations of generally known types. The pigs were kept in semi-confinement, ten pigs in an open cage until an average weight of 50 kg wa~ achieved, and then 20-22 p~gs in a much larger open cage until market weight of approximately 100 Xg had been reached. Animals were sheltered and had free access to water and feed. Every fourteen days the animal~ in all groups were weighed, the daily food consumption, and the food consumed per kg of body weight gain were calculated. Animal~ were sacrificed at intervals and meat qua~ity ob~er~ed.
In Table 2 the average food co~sumption per day is given. Table 3 show~ the average food uptake or conversion per kg of weight gain, which i~ a mea~ure of feed efficiency.
The feed efficiency of th~ treated animals was considerably better than the castrated or intact animals at almost every eat ineerval, 21 t 33065 1 O ¦ O ~ o G
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~' 22 ~ 1 330651 Differences between groups from birth to 49 days are minimal. F~om 49 to 105 days food consumption of treated pigs was aDout the sa~e a~ the intact control g~oup. Daily weight gain of treated pig~ wa~ markedly higher throughout this period (e.g. on day 63 the 43 lb treated pigs had gained 475 grams ~10.5 lb8] over the previous 14 days, with a feed conversion of 1.3, compared to the 33 lb castrate which gained 380 gram~ [8.4 lbs]. On day 105 treated pigs gained over the previous 14 days 775 grams 117 lb~] and castrates 590 gram~ for a 35~ better conversion for the treated pigs).
From day 119 to 163 treated pig~ were gaining slightly more than castrates on con~iderably less feed.
~reated were 22 lbs heavier than ca~trate~ throughout the period 100-179 dayc with a much higher proportion of meat to fat ~44~ less back fat).
From 163 to 190 day~ feed consumed and daily gain dropped in treated and castrates, although feed efficiency was still much bett~r in troat~d. It should be noted that on day 161 treated pig~ axe at or near U.S. market weight (180 lbs for U.S. No. 1 Grade). Feed efficiency for treated pigs is 3.1. In comparison, the castrates averaged 158 lbs. It required about 178 days for the castrates to reach 180 lbs. The feed efficiency for the castrates at that time is about 4.5. That is, another 15-16 days of feeding is required (at this feed efficiency 4.0-4.5) to reach market weight. Approximately 100 additional pounds of feed is required for each castrate to reach market weight. The data is summarized in Table 4 below.

Table 4. Food Conver~ion and ~ody Weight of Landrace Pigs DaY Food Efflciency Body Weight 63 treated 1.3 l9kg ~42 lbs) 49 castrate 1.7 lOkg ~22 lbs) 105 treated 2.5 45~g ~99 lbs) 105 castrate 3.2 33kg (73 lb~) 147 treated 2.6 72kg (158 lbs) 147 castrate 3.4 62kg ~136 lbs) 161 treated 3,1 82kg ~180 lbs) 161 castrat~ 3.6 72kg (158 lbs) o 179 treated 3.9 lOO~g (220 lbs) 179 castrate 4.6 90kg (198 lbs) Two main ef~ects o~ the treated pigs compared to castrates can be seen. First, there is a very marked increase in daily body weight gain for about the same feed consumed up to approximately day 119 ~53kg or 115 lbs).
This is at a maximum from day 63 ~15~) to day 105 (40~).
Secondly, a marked decrease in food consumption occurs from day 119 to day 161 with a ~light increase in daily weight gain compared to castrates. This i8 better than a 30 increase in feed ef~iciency.
Example II
In another experiment 150 male Landrace-Yorkshire pigs were divided into group~ of 50, 50 of which were given 50 mg of estradiol benzoate, i.e., the 3-benzoate compound plus 250 mg of progesterone caproate subcutaneously in the inguinal region on day 1, 50 were castrated at the same time, and 50 left intact, and the weight gain and feed consumption of the several groups was measured.
Table 5 shows the average body weight at the stated interval plotted against age i~ days for the intact, castrated and treated male pigs. The treated pigs were considerably heavier than the other two groups throu~hout the test period. Tha treated an~als reached their market weight of 100 kg in 166 days, which was 20 days sooner than the other two group~.
The material employed may be prepared as described in Example Vl.

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`` 25 ~ 1 330651 Table 6 below showa the average food consumption in kg for the three groups at ~arious time intervals throughout the growth cycle. The treated hybrid pig8 consumed slightly more feed per day than the other two groups, but with a con~iderably greater weight increase.
In addition, they reached market weight much earlier.
This means a considerable saving in feed, aince the final growth phase before slaught~r i~ the one with the poorest feed efficiency. The average food uptake or conversion per kilogram of weight fain ~feed efficiency) is shown in Table 7.

'- 26 1 330651 O ~ O i N N ~ N

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27 ~ 1 330651 Table 8 below ~et~ forth a compari~on of the feed efficiencie~ obtained in this ex~mple in three ways during three growth phases; namely, the actual average feed consump-tion per kg weight gain during that phase, the relative consumption (Index) taking the con~umption o~ the castrated animals as the base (Index Yalue ~ 100), and the percentage change from the ba6e. ~he first phase, from 20-50 kg of live weight, represent~ the post-weaning growth phase of pigs on a high protein diet. In th$s phase, it can be seen that the treated animals have an actual feed eficiency of 2.Q6, compared with 3.0Q for the intact, and 3~39 for the ca~trated animals. During this phase, the treated animals have a 15.64 higher feed efficiency compar~d with the castrated and about 4~ higher than the ~ntact animals. In the next phase of 50-100 ~g, or the ~o-called finishing phase, the actual feed efficiency of the treated animals i8 3.27 compared with 3.62 for the intac~ a~d 3.73 for the ca~trated. Probably the most important compari~on i8 the overal feed e~ficiency from weaning to market weight, i.e., over the ~ull range o 20-100 kg. ~ere, th~ treat~d a~imals show an overall actual average feed efficiency of 3.08 compared with 3.32 for intact, and 3.57 for castrated pigs. In add~tion, the treated reach market weight of 100 kg in a con~iderably shorter time. Thi~ not o~ly means an additional feed saving but a saving in labor costs, heating and other expenses in producing the animal~. More animals can thus be brought to market ~ince it ~ecomes pos~ible to have more production cycles from weaning to ~laughter per year for a given 8ize facility.

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-~ 29 1330651 Example III
The time required for the administered femsle gonadal steroidal compound~ to become cleared or dis~ipated from the system of the ani~al $8 conveyed graphically in Figs. 1, 2 and 3.
Brief Description of the Drawings Fig. 1 is a comparati~e group of plots of the level of estradiol in the blood gerum of the animal versus the age of the animals during the exper$ment for each oS intact animals, castrated animal~ a~d animals treated in accordance with the invention, the regression or trend line of each of the graphs being shown ~ broken line~;
Fig. 2 i~ a ~im~lar group of graphs for serum concentration of progest~rone~ and Fig. 3 i~ a simllar group of plot~ for the serum concentration of te~to~terone in tAe various group~ of animals.
In order to determine the ~erum levels of the hormones, estradiol, proge~terone, and te~to~terone ~n animals treated in accordance with the invention in comparison to 6imilar animals both intact and castrated, the blood serum for groups of each of tbe~e animals wa~ analyzed for the content therein of the hormones in ~ue~tion by means of ~nown radioimmunoassay tecbni~ue~ at intervals fol~owing the administration by injection into the treated animals and the results of these analyses are set forth graphically in Figs. 1-3. The injection composition consisted of the preferred combination of 50 mg e~tradiol and 250 mg o~
progesterone dissolved or di6persed witbin olive oil as a carrier, the admini trat$on being applied at day 1. The variation in the analyzed value~ of tbe re~pective hormones at each time o~ measurem~nt i~ indicated in the graphs by solid vertical bars.
As i~ ~een from Fig. 1, tbe ~ubcutaneou~ dose of estradiol in oil is cleared by 28 day~, reaching by that time a basal level compared w~th the castrate and intact animals. Pig. 2 demon~trates that the proge~teron~ level~
in the treated an~mA~ ewi~e come to the ~ame level8 a~
the intact animals by day 28. ~he intact _nLmals exhibit a secondary increase that repre~ent~ an endogenous secretion .

of progesterone from the tes~s, and to a lesser extent from the adrenals, frQm day 28 to day 84 with a peak at day 56.
~oth the treated and the ca~trated anLmals in this ~ime period have a much small~r rise in endogenous progesterone, coming entirely fxom the adrenal cortex in the case of castrated, and mostly from the adrenal cortex in the case of the treated animals. Fig. 3 show~ the endogenous levels of androgen expressed a~ testo~terone, in the three groups of animals. Thi~ is testo~terone from the testis and, a6 would be expected, in the ca~tratad a~imals i~ almost zero. The treated animals how a fir~t peaX rise $n t~stosterone beginning at day 7 ~imilax to the intact a~imals but to a lower level. Interestingly e~ough, the secondary phase which shows an increase in te~tosterone after day 28, as measured by blood level~, is greate3t in the treated animals.
The dotted linear regre~sion or trend line in the treated animals shows this incr~as~ guit~ clearly. This represents the induced anabolic effect of the inventive treatment and is part of the improv~d growth ~ffect thereof.
Example IV
This exampl~ ~cveal~ thc effect of the induction of increased growth hormones and anabolic ho~mones in animals treated i~ accordance with the invention on meat quality as detenmined by the ratio of l~an meat to ~at. Carcasses obtained from the various groups of animals corresponding to the experiments described above are evaluated on the slaughter line at ~he end of the experiment. The average thickness of back fat on ~plit carca~es wa~ 56 mm for ;~
castrate, 48 mm for intact and 39 mm for treated animals.
The average back fat then, was q3.6~ thicker in castrated animals compared with those ~reated according to the invention ;
and 23~ thicker in intact animal~ than in treated animals.
Similar reductions in fat in ~reated animal~ were obtained in other meat cuts 8uch a~ la~t rib cut~, bellie~ and hams.
Example V
This example lllu~trate~ the application of the invention to fish, specifically rainbow trout ~Salmo qairdneri) as well a~ ~he in~luenc~ of different growing ~ 1330651 conditions, especially temperature and light, on the respons~
of the fish to the instant treatment.
These experiment~ were carried out with many thousand of the rainbow ~rout at two different fish farm locations; namely, ~ish fa~m ~Z~ where the average water temperature was cooler in th6 range of about 8-13C and the number of light days waff fewer, and fish farm "S~ where the water temperature was somewhat higher in the range of about 10-13~C and the number of light days was greater. The fish in the experiment at each location were separated into two groups, the fir~t group being fed with the usual pellet-ized feed or ~bricket~ and the other were fed the same feed on which estradiol benzoate wa~ incorporated at a concentra-tion of 0.5~ by w~ight a~d given to the fish for four consecutive days, ~eginning with the first f~eding o~ the fish at an age of foux month~, after which the treated and untreated fish were ~upplied with the same feed on the same basis. ~hese experimRnt~ were terminated when the fish reached their consumption or ma~eting weight which occurred at the age of 17 month~ fo~ the ~ish at the wanmer location and at the age oX 20 ~o~ths ~or the fish in the colder location.
At interval~ during th~se feeding experiments, the ~ish were evaluated as to w~ight, and this data is summarized in the following table which i~ divided into two parts corresponding to the di~erent locations.

,~ 32 1 33065 1 Table 9A. Fishfarm ~zu _ Water temperature - 8-13C
AYeraqe Weight in Grams Age in Months Control Treated 1.85 1.85 4 6.4 7.1 5 15.0 16.1 6 24.0 24.0 7 32.0 35.0 8 38.0 ~5.0 9 44.0 51.0 10 52.0 59.0 11 63.0 ~4,0 12 75.0 9~.0 13 85.0 99.0 14 98.0 115.0 lS
118.0 135.0 16 131.0 156.0 17 148.0 183.0 la 178.0 208.0 19 ~90.0 227.0 20 ~ 33 '' 1 330651 Table 9B. Fishfarm ~S - Water Temperature ~ 10-13C

Average Weight in Gr~m~ Age in Months ~ontr~l Treated 1.85 1.85 4 6.30 6.50 5 14.50 15.0 6 21.~ 29.~ 7 28.5 38.0 8 39.0 49.0 9 lo 44.0 61.a ' 10 55.0 72.0 11 68.0 105.0 12 94.0 139.0 13 120.0 161.0 14 148.0 181.0 15 172.0 196.0 16 20~.0 249.0 17 It will ~a observed ~rom tha above tabulations that the weight of th~ tr~ated ~ish wa~ con~i~tently higher throughout the g~owth p~riod o~ the fish and wa~ substantially greater than that of the unt~eated or control fish at the end of both o~ the~e expeximent~, ~uch incr~a~c being over and above the d~ffe~ence~ in w~ight attributable to the more ~avorable ~owin~ con~tion~ at farm ~S.
The following examples are illustrative of the preferred methods of producing growth promoting materials according to the invention. It will be appreciated from applicants' disclosure herein that a variety of equivalent materials may be used~ For example, equivalent hormone compounds may be used in addition to the specific materials employed and a variety of metabolizable vehicles may be used.
In particular edible oils, such as vegetable oils, may be used. Animal oils may also be used, particularly for preparing hormone containing feeds. The hormone is preferably incorporated in the oil with stirring after heating the oil, e.g., to between about 35-100C. When the hormone preparation is to be used by injection, the oil is clarified to an acceptable standard, such as U.S.P., and sterilized, prior to incorporation of the hormone therein. Unsaturated oils are preferred for use by injection.

.. . . ..

~L4 t 33065 1 E xample VI
Injectible hormone preparations according to the invention may be prepared by incorporating the hormone materials into an oil vehicle, as described herein. These preparations are particularly suited for administration to mammals, such as pigs and cattle, for example with dosages as referenced in Table 1. A suitable vehicle for the injectible material, sterilized olive oil, is first heated to about 80C in a stirred flask having an electrical heating jacket. To the heated oil is added 25 mg/ml of estrogen (estradiol 3-benzoate) and 125 mg/ml of progestagen (17~-hydroxyprogesterone caproate). The hormone and vehicle are stirred for about 20 minutes until ! the hormone is in solution, cooled, and is then dispensed into 150 ml ampules and sealed.
Example VII
i An edible hormone preparation, which may be used as described in Example, V, may be prepared by D incorporating the hormone material into a ration for the ! 20 particular animal. Rations prepared as described herein are particularly suited for administration to fish. A
suitable ration for trout fingerlings may be prepared by using a commercial basal fingerling trout ration (Purina Mills, Inc., PURINA~TROUT C~O ~ . The basal ration is pelletized to form particles of about 3/~ inch. The pelletized particles are then crushed in a hammer mill to a form particles of which about 90~ or more will pass through a Tyler #28 screen. The oil added to the basal ration, about 10~ of the total ration added as fish oil, is divided into two portions, a first portion of 6% of the total ration and a second portion of 4~ of the total ration. The first portion is heated to a temperature of about 65C
, and is sprayed onto the crushed basal ration in a tumbling , drum and mixed until the oil is uniformly blended into the 3 ration. The second portion of oil is heated to a temperature of about 80C in a stirred vessel and 0.5~, based on the total ration, of estrogen (estradiol 3-benzoate) is added to the second portion of oil and stirred for about 20 minutes until the hormone is dispersed in the oil. ~he secoDd portion of oil containing the .

, ~5 1 33065 1 -hormone is sprayed on the ration, containing the first oil portion, in a tumbling drum and mixed until the oil and hormone are uniformly blended into the ration. The ration is then complete and may be packaged.
ExamPle VIII
An edible hormone preparation suitable for poultry, such as cbickens, is prepared as desceibed in Example VII. The basal ration is a commercial chick ration (Purina Mills, Inc., PURINA~3CHICK STARTENA~MP). The basal ration is pelletized to particles of about 3/8 inch and then crushed in a hammer mill to form particles 95% of which are between about ~24 and #6 ~yler screen size. The oil added to the ration is 4~ of the total ration. The hormone is introduced into the whole oil portion and applied to the ration as described in Example VII. The hormone is 0.1% estrogen (estradiol diproprionate) and 0.4~
progestagen (17-hydroxyprogesterone caproate) based on the total ration weight.

Claims (31)

1. The method of producing an injectible growth promoting material for administration to non-ruminant animals comprising heating an injectible oil vehicle, adding an estrogen hormone material to the vehicle, adding a progestagen hormone material to the vehicle and dispersing the hormone materials in the vehicle, the estrogen and progestagen hormone materials being effective at the proportions added, when non-implantatively administered to a non-ruminant animal at dosage levels, to temporarily increase substantially the level of each such hormone material in the animal and to delay its sexual maturation, without impairing its primary sexual development, until after the time of slaughter without unacceptable residual amounts of either of the hormone materials in the slaughtered animal.

2. The method of claim 1 wherein the weight proportion of estrogen to progestagen is from about 1/1 to 1/20.

3. The method of claim 1 wherein the estrogen hormone is selected from the group consisting of estradiol diproprionate and estradiol 3-benzoate.

4. The method of claim 1 wherein the progestagen is 17.alpha.-hydroxyprogesterone caproate.

5. The method of claim 1 wherein the vehicle is heated to between about 35-100°C prior to dispersing the hormone materials in the vehicle and the vehicle is stirred to disperse the hormone materials,

6 The method of claim 1 wherein the estrogen hormone is incorporated in the vehicle at a level of up to about 100 mg per ml of vehicle.

7. The method of claim 1 wherein the progestagen is incorporated in the vehicle at a level of up to about 250 mg per ml of vehicle.

8. A growth promoting material produced by the method of claim 1, 2 3, 4, 5, 6 or 7.

9. A method of preparing a non-ruminant animal food product containing an edible growth promoting hormone preparation comprising preparing a basal ration for the non-ruminant animals and adding an edible oil to the basal ration the edible oil containing at least one of a female gonadal steroidal hormone, the level of hormone being effective, when the treated ration is fed to non-implantative animals at about the neonatal period of development, to substantially increase the level of such hormone in the animal and to delay its sexual maturation, without impairing its primary sexual development, and to generally delay its sexual maturation until after slaughter without producing an unacceptable residual amount of the hormone in the slaughtered animal.

10. The method of claim 9 wherein the hormone is an estrogen hormone.

11. The method of claim 9 wherein the hormone includes a progestagen hormone.

12. The method of claim 9 wherein the hormone is a mixture of an estrogen and a progestagen.

13. The method of claim 12 wherein the weight proportion of estrogen to progestagen is between about 1/1 to 1/20.

14. The method of claim 10 wherein the hormone is selected from the group consisting of estradiol diproprionate and estradiol 3-benzoate.

15. The method of claim 11 wherein the hormone is 17.alpha.
-dihydroxyprogesterone caproate.

16. The method of claim 9 wherein the oil is coated on the ration.

17. The method of claim 9 wherein at least a portion of the oil is heated to between about 35-100°C
and the hormone is dispersed in the oil.

18. The method of claim 17 wherein the hormone is incorporated into the oil at a level of between about 0.5 to 2.0% by weight of the total ration.

19. A non-ruminant animal feed product produced by the method of claim 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18.

20. The use of a compound comprising a combination of an estrogen and a progestagen steroidal compound in which the weight of said progestagen compound exceeds that of said estrogen compound, for treating sexually intact meat-producing non-ruminant domestic anmials for market, to improve the yield and increase the proportion of lean to fat meat obtained therefrom when the animal is slaughtered after achieving a marketable body weight, the compound being adapted to be non-implantatively administered to the animal to be treated at a time during substantially its neonatal stage of development in at least one dosage in an amount which is sufficient to produce in the animal an essentially immediate, temporary substantial increase in the level of each of said steroidal compounds in the animal's system, said temporary increase persisting for a period that is short in duration relative to the time interval between the time of such administration and the date of slaughter, such dosage being effective to delay sexual maturation of the animal so that sexual maturation does not occur prior to the date of slaughter of the animal without substantially impairing its sexual development and growth function, said animal being at least substantially free of any residual amount of the thus-administered steroidal compounds at the date of slaughter.

21. The use according to claim 20 wherein said combination is a mixture of said steroidal estrogen compound and said steroidal progestagen compound.

22. The use according to claim 20 wherein said progestagen compound is adapted to be administered in substantially greater amounts than said estrogen compound.

23. The use according to claim 22 wherein said progestagen compound is adapted to be administered in an amount about five times greater than the amount of said estrogen compound.

24. The use according to claim 20 wherein said animals are non-ruminant uncastrated male mammals.

25. A use according to claim 20 wherein said steroidal estrogen and progestagen compounds are adapted to be administered to said animals by injection of a solution or dispersion thereof in an oily carrier.

26. The use according to claim 20 wherein the amount of each said dosage is insufficient to produce substantial breast enlargement of the animal receiving the same.

27. The use according to claim 20 wherein the duration of said temporary increase of the level of said hormonal compound does not exceed about 30 days.

28. The use according to claim 20 wherein said steroidal compounds are non-implantatively administered in the form of an intimate admixture.

29. The use according to claim 20, 21, 22 or 23 wherein said livestock animal is pig or poultry.

30. The use according to claim 20, 21, 22 or 23 wherein said at least one dose is adapted to be incorporated in said animal's feed.

31. The use according to claim 20, 21, 23 or 23 wherein said at least one dose is adapted to be administered to said animal by injection.