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Title:
ARTIFICIAL INSEMINATION OF PIGS
United States Patent 3681490
Abstract:
A process for the artificial insemination of female pigs, which comprises the step of introducing into the environment of the female pig immediately prior to testing for oestrus response at least one compound selected from 5α-androst-16-en-3-one and 3α-hydroxy-5α-androst-16-ene. In a preferred process the compound is administered in the form of a spray of liquid droplets bearing the steroid compound.


Inventors:
Melrose, David R. (Reading, EN)
Patterson, Ronald Lowdon Straiton (Crickham near Wedmore, EN)
Reed, Hugh Charles (Brent of Selby, EN)
Application Number:
04/843789
Publication Date:
08/01/1972
Filing Date:
07/22/1969
Assignee:
Nationale Research Development Corporation (London, EN)
Primary Class:
Other Classes:
514/178
International Classes:
A61K31/16; (IPC1-7): A61K27/00
Field of Search:
424/238,242,2
View Patent Images:
Other References:

Chemical Abstracts (1) Vol. 69, entry 74223w, 1968 .
Chemical Abstracts (2) Vol. 69, entry 7568m, 1968 .
Nyhan, The Veterinary Record, Vol. 76, No. 24, pg. 656-658, June 13, 1964 .
Melrose, The Veterinary Record, Vol. 78, No. 5, pp. 159-168, 1966.
Primary Examiner:
Huff, Richard L.
Claims:
1. In a process for the artificial insemination of female pigs, which includes the step of testing for oestrus response prior to attempted insemination, the improvement which comprises the step of introducing into the environment of the female pig immediately prior to testing for oestrus response at least one compound selected from 5α-androst-16-en-3-one

2. A process according to claim 1, in which the compound is administered in

3. A process according to claim 1, in which the quantity of steroid

4. The process according to claim 1, wherein the compound is

5. The process according to claim 4, wherein the compound is introduced into the environment of the female pig with an inert carrier comprising a

6. The process according to claim 1, wherein the compound is

7. The process according to claim 6, wherein the compound is introduced into the environment of the female pig with an inert carrier comprising a

8. A composition for determining the time of oestrus in a process for the artificial insemination of female pigs, which comprises at least one steroid compound selected from 5α-androst-16-en-3-one and 3α-hydroxy-5α-androst-16-ene and an inert carrier which will enable the steroid compound to be presented to the pig and detected by the

9. A composition according to claim 8, in which the inert carrier is a

10. A composition according to claim 8, in which the inert carrier

11. A composition according to claim 8, in which the inert carrier is a

12. A composition according to claim 8, in which the inert carrier comprises an aerosol propellant present in bulk and the composition is

13. A composition according to claim 12, in which the aerosol propellant is

14. A composition according to claim 12, comprising from 100 to 1000 μg.

15. An aerosol container containing a composition according to claim 12.

16. The composition according to claim 8, wherein the compound is

17. The composition according to claim 16, wherein the inert carrier

18. The composition according to claim 8, wherein the compound is

19. The composition according to claim 18, wherein the inert carrier comprises a perhalogenated lower alkane aerosol propellant.

Description:
The practice of artificial insemination of female pigs is becoming a matter of increasing importance to the pig breeder. As more pigs are raised intensively for pork and bacon production, it is necessary to keep more boars on the farm to serve the increasing number of sows. This is undesirable because the pedigree of the breeding boars may be low, there is a danger of transmitting disease and hereditary weakness, and the cost of purchase, housing and raising tested boars is substantial.

Artificial insemination offers the pig breeder the important opportunity of improving his stock by the use of top quality semen obtained from approved boars.

In the female pig, the optimum time during the period of oestrus for artificial insemination is relatively short and is usually judged subjectively by the response of the sow to pressure on her back. The majority of sows will give a positive result to this test in the absence of a boar, in which case insemination can be easily carried out. However, about 20 percent of sows will not respond, thereby negating attempts at insemination. The sight, sound or smell of the entire male is apparently necessary to stimulate the oestrus response in these particular animals.

In view of the disadvantages of using boars, or using crude body fluids derived from boars, chemical compounds with physiological activity which stimulate the oestrus response in sows are of major interest and importance. It has now been found that two closely related steroid compounds have the desired activity.

In a process for the artificial insemination of female pigs, the present invention provides the step of introducing into the environment of the female pig immediately prior to testing for oestrus response at least one compound selected from 5α-androst-16-en-3-one and 3α-hydroxy-5α-androst-16-ene.

The steroid compound is preferably introduced into the air the pig is breathing, conveniently by keeping the pig in an enclosed space and spraying the steroid compound into this enclosed space to introduce a large number of very small particles or liquid droplets bearing the steroid compound. It has been found that very soon after inhaling the particles or droplets bearing the steroid compound the pig will give a positive response to the back pressure test almost immediately if in oestrus indicating that it is timely to attempt artificial insemination. As mentioned above, if artificial insemination is attempted in the conventional manner, about 20 percent of the pigs do not respond to the back pressure test, and in these cases it is not possible to establish the optimum time to attempt insemination and attempts are usually unsuccessful unless the time is right. By using the process of the present invention about half of the 20 percent will give a response to the back pressure test. The present invention thus enables artificial insemination of pigs to be carried out in a more efficient and expeditious manner than is possible at present.

A further feature of the invention provides a composition for determining the time of oestrus in a process for the artificial insemination of female pigs comprising 5α-androst-16-en-3-one and/or 3α-hydroxy-5α-androst-16-ene, together with an inert carrier which will enable the steroid compound to be presented to the pig and detected by the sense of smell.

Preferably the composition is administered in the form of a spray which may be a powder, but is preferably a liquid, particularly an aerosol spray which may be delivered from an aerosol container, and accordingly a preferred composition according to the invention is one in which the inert carrier comprises an aerosol propellent.

Any of the customary propellants, compatible with the steroid compounds, may be used, for example the various Freons and Arctons, that is to say the various perhalogenated lower alkanes. The steroid compounds may be introduced into the aerosol propellant in a small quantity of an organic solvent, preferably a volatile solvent such as diethyl ether. Only very small quantities of the steroid compounds are required for inhalation by the pig and successful results have been obtained with aerosols containing about 100 to 1,000 μg. per 100 g. of propellant which are sprayed to release about 2 g. of mixture for every pig, that is to say about 2 to 20 μg. of steroid compound.

The following Examples are given to illustrate the compositions and process of the invention:

EXAMPLE 1

5α-androst-16-en-3-one is introduced in 0.5 ml. diethyl ether into a few milliliters (about 10 ml.) of Freon 12-11 (a 50/50 mixture by volume of dichlorodifluoromethane and trichlorofluoromethane) contained in an open aerosol can. A further 1.5 ml. ether is added to this composition to give a total volume of ether equal to 2.0 ml., a quantity common to all formulations. The weight of the mixture is made up to 50 g. with more propellant, the aerosol can is sealed in the conventional way, and fitted with a valve designed to deliver a fine spray when operated. This aerosol can is designated A.4 and contains 160 μg. 5α-androst-16-en-3-one in 50 g. propellant. A similar aerosol is formulated containing 150μg. 3α-hydroxy-5α-androst-16-ene and designated B.5.

The back pressure test is applied to all sows and gilts presented for insemination and it is found that there is negative response in about 20 percent of the sample. Aerosol compositions of the invention are tested against this 20 percent sample immediately after the negative response is obtained. The sow is maintained in an enclosed space and approximately a 2 second burst from the aerosol spray introduced into the air releasing about 2 g. of mixture. After 1 to 2 minutes, the back pressure test is applied again when it is found that approximately 50 percent of the sows and gilts, previously negative, now give a positive response. A series of control experiments are run in which a few drops of a mixture of boar preputial fluid and urine are placed on the snout of the female. This practice is not to be recommended for the reasons of hygiene discussed earlier, and it is found that in this control positive results to the back pressure test are obtained only in about 25 percent of the previously negative sample.

The following figures show the number of positive results obtained from previously negative sows and gilts when tested with the control and steroid compositions, expressed as a ratio of the number tested.

steroid composition control composition A.4. 11/23 6/22 B.5. 10/19 8/19 EXAMPLE 2 An aerosol can designated A.8 is made up in a manner identical to that for A.4 except that it contains twice the amount of 5α-androst-16-en- 3-one. This composition is tested in the same way as in example 1 against a control comprising a blank aerosol, that is to say, containing diethyl ether and propellant only, instead of preputial fluid and urine. The following figures show the number of positive results obtained from previously negative sows and gilts when tested with the control and steroid compositions, expressed as a ratio of the number tested.

Steroid Composition A.8 Control Composition 22/40 0/40