Method and compositions for synchronizing time of insemination in gilts

1. A method for synchronizing time of insemination in a gilt, the method comprising the steps of:

administering to the gilt a hormone for synchronizing estrus;

monitoring estrus on the fifth day after the last daily administration of the hormone for synchronizing estrus, and then, if the gilt is in estrus, administering to the gilt a single dose of a gonadotropin-releasing hormone, without administration of any other hormone for synchronizing ovulation, and

inseminating the gilt on the fifth day after the last daily administration of the hormone for synchronizing estrus; and

inseminating the gilt on the sixth day after the last daily administration of the hormone for synchronizing estrus wherein estrus is not monitored on the sixth day after the last daily administration of the hormone for synchronizing estrus.

2. The method according to claim 1 wherein the gonadotropin-releasing hormone has the formula

or a solvate, a hydrate, or a pharmaceutically acceptable salt thereof wherein

R 1 and R 2 are independently in each instance hydrogen, or are independently selected from the group consisting of alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, haloalkyl, aryl, heteroaryl, arylalkyl, and heteroarylalkyl, each of which is optionally substituted, or R 1 and R 2 and the attached carbon form a carbocycle or heterocycle;

R 5 is hydrogen or alkyl; and

X is hydrogen, or X is selected from the group consisting of alkyl, cycloalkyl, heteroalkyl, optionally substituted alkylene-carboxamide, and HNC(O)NR 3 R 4 , where R 3 and R 4 are in each instance independently selected from the group consisting of hydrogen, alkyl, heteroalkyl and haloalkyl.

3. The method according to claim 2 wherein the gonadotropin-releasing hormone is selected from the group consisting of compounds of the formula of claim 2 wherein

a) R 1 is 1H-indol-3-yl-methyl, R 2 is hydrogen, X is CH 2 (CO)NH 2 ; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R;

b) R 1 is hydrogen, R 2 is hydrogen, X is CH 2 (CO)NH 2 ; and R 5 is hydrogen;

c) R 1 is 1H-1-benzyl-imidazol-4-yl-methyl, R 2 is hydrogen, X is ethyl; and R 5 is hydrogen;

d) R 1 is 2-methylpropyl, R 2 is hydrogen, X is ethyl; and R 5 is hydrogen;

e) R 1 is 2-naphthylmethyl, R 2 is hydrogen, X is CH 2 (CO)NH 2 ; and R 5 is hydrogen;

f) R 1 is t-butoxymethyl, R 2 is hydrogen, X is ethyl; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R;

g) R 1 is benzyl, R 2 is hydrogen, X is CH 2 (CO)NH 2 ; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R;

h) R 1 is t-butoxymethyl, R 2 is hydrogen, X is HN(CO)NH 2 ; and R 5 is hydrogen;

i) R 1 is 1H-indol-3-yl-methyl, R 2 is hydrogen, X is ethyl; and R 5 is hydrogen;

j) R 1 is methyl, R 2 is hydrogen, X is hydrogen; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R;

k) R 1 is 1H-indol-3-yl-methyl, R 2 is hydrogen, X is ethyl; R 5 is methyl; and the configuration of the carbon to which R 1 is attached is R;

l) R 1 is methyl, R 2 is hydrogen, X is CH 2 (CO)NH 2 ; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R;

m) R 1 is 4-aminobutyl, R 2 is hydrogen, X is HN(CO)NH 2 ; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R;

n) R 1 is methyl, R 2 is methyl, X is HN(CO)NH 2 ; and R 5 is hydrogen; and

o) R 1 is ethyl, R 2 is hydrogen, X is hydrogen; R 5 is hydrogen; and the configuration of the carbon to which R 1 is attached is R.

4. The method according to claim 1 wherein the insemination is an artificial insemination.

5. The method according to claim 1 wherein the gonadotropin-releasing hormone is administered in an effective amount of 200 μg.

6. The method according to claim 1 wherein the dose of the gonadotropin-releasing hormone is administered using a method selected from the group consisting of use of a deposition catheter, manual administration, and injection.

7. The method according to claim 1 wherein the gonadotropin-releasing hormone is triptorelin.

8. The method according to claim 1 wherein the gonadotropin-releasing hormone is administered in an effective amount of 1 μg to 500 μg.

9. The method according to claim 1 wherein the gonadotropin-releasing hormone is administered in an effective amount of 100 μg to 300 μg.

10. The method according to claim 6 wherein the gonadotropin-releasing hormone is administered using a deposition catheter.

11. The method according to claim 1 wherein the hormone is in acetate form.

12. The method according to claim 1 wherein the hormone is administered in a composition comprising a gel.

13. The method according to claim 12 wherein the gel is a methylcellulose gel.

14. The method according to claim 1 wherein the gonadotropin-releasing hormone is administered intravaginally.

15. The method according to claim 1 wherein the method results in fertility of the gilt.

16. The method according to claim 1 wherein the hormone that synchronizes estrus is altrenogest.

17. The method according to claim 1 wherein the gonadotropin-releasing hormone is administered in a composition with a pH of 5 to 6.

18. The method according to claim 1 further comprising the step of exposing the gilt to a boar.

19. The method according to claim 1 wherein the hormone for synchronizing estrus is administered by feeding.

20. The method according to claim 1 wherein the gonadotropin-releasing hormone is administered 118 to 124 hours after the last daily administration of the hormone for synchronizing estrus.