METHODS FOR SYNCHRONIZATION OF ESTROUS CYCLES AND OVULATION FOR FIXED TIME ARTIFICIAL INSEMINATION IN CATTLE
The present application relates to the reproductive management of cattle, and more particularly, to the synchronization of estrous cycles and ovulation for fixed time artificial insemination of cattle with the addition of a second prostaglandin treatment in Ovsynch-type protocols resulting in the complete regression of the corpus luteum and an increase in pregnancies per artificial insemination in multiparous cows.
1 . A method for synchronizing the estrous cycle in cattle, the steps comprising:
(a) administering a first dose of a GnRH composition to a lactating cow during an estrous cycle in an amount effective to stimulate a surge in the circulating concentrations of LH and FSH;
(b) subsequent to step (a) and after a first period of time sufficient for development of a dominant follicle and a functional corpus luteum, administering a first dose of a PGF2α composition in an amount effective to stimulate corpus luteum regression;
(c) subsequent to step (b) and after a second period of time sufficient for initiating the process of corpus luteum regression, administering a second dose of a PGF2α composition in an amount effective to effectuate complete corpus luteum regression;
(d) subsequent to step (c) and after a third period of time sufficient for complete luteal regression, administering a second dose of a GnRH composition in an amount effective to stimulate ovarian follicular development and subsequent ovulation; and
(e) subsequent to step (d) and after a fourth period of time, breeding the cow using artificial insemination.
2 . The method of claim 1 , wherein the first period of time is between about 144 hours and about 192 hours.
3 . The method of claim 1 , wherein the second period of time is between about 0 hours and about 56 hours.
4 . The method of claim 1 , wherein the third period of time is between about 0 hours and about 48 hours.
5 . The method of claim 1 , wherein the fourth period of time is between about 0 hours and about 24 hours.
6 . The method of claim 1 , wherein the fourth period of time is between about 8 hours and about 20 hours.
7 . The method of claim 1 , wherein the lactating cow is primiparous.
8 . The method of claim 1 , wherein the lactating cow is multiparous.
9 . The method of claim 1 , wherein breeding occurs during heat stress conditions.
10 . The method of claim 1 , wherein breeding occurs during non-heat stress conditions.
11 . The method of claim 1 , wherein the GnRH composition is a gonadorelin composition.
12 . The method of claim 11 , wherein the gonadorelin composition is gonadorelin acetate.
13 . The method of claim 11 , wherein the gonadorelin composition is gonadorelin hydrochloride.
14 . The method of claim 1 , wherein the PGF2α composition is a cloprostenol composition.
15 . The method of claim 14 , wherein the cloprostenol composition is cloprostenol sodium.
16 . The method of claim 1 , wherein the PGF2α composition is a dinoprost composition.
17 . The method of claim 16 , wherein the dinoprost composition is a dinoprost tromethamine composition.
18 . The method of claim 1 , wherein at the period of time subsequent to step (c) and before step (d) circulating P4 concentrations are less than at the period of time subsequent to step (b) and before step (c).