docgraybull
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A newsletter article from Dr. Glenn Selk at Oklahoma State University that I thought you might find interesting and/or informative.
COW/CALF CORNER
The newsletter
January 28, 2005
In this issue:
Plan Ahead for Heat Synchronization Methods for Replacement Heifers
Producers that plan to use artificial insemination as part or all of this upcoming spring breeding season should start their preparations immediately. A popular synchronization protocol for heifers involves the feeding of an additive, and the feed must be ordered and delivered at the proper time. Melengestrol acetate (MGATM Pfizer Animal Health) is a feed additive commonly used in heifer feedlot rations to block the cycling activity of heifers. Melengestrol acetate is a synthetic progestin that has "progesterone-like" activity. When fed for a short period of time and then removed from the diet, the sudden absence of the progestin tends to allow a large percentage of cattle to exhibit heat together. Compared to normal heats, fertility at this first heat after MGATM removal has been reduced. Subsequent heats have returned to normal fertility. Armed with this knowledge, researchers have outlined an estrous synchronization protocol using MGATM and a prostaglandin injection. This program calls for the feeding of melengestrol acetate at the rate of 0.5 milligrams per head per day for 14 days. After 14 days, MGATM is removed from the feed. Most of the heifers will then exhibit heat over the next 8 days. Nineteen days after the MGATM feeding has stopped, each female is injected with prostaglandin to interrupt the next cycle. One to six days later, females are bred following detected standing heat. (See time line below). Research at several experiment stations has indicated that this method has induced some non-cycling replacement heifers to begin cycling, thereby increasing the percentage of those cattle bred early in the insemination season.
An important consideration is that the MGATM/prostaglandin synchronization program must be started 34-37 days before the start of the breeding season. This means that prior planning must be done to assure that the feed containing MGATM is prepared and ready to feed five weeks before the date of the first breeding. This synchronization method is designed to work best with replacement heifers.
Day 0 Start MGA
Day 14 End MGA
Day 33 Inject Prostaglandin
Day 34-40 Heat detect and breed.
COW/CALF CORNER
The newsletter
January 28, 2005
In this issue:
Plan Ahead for Heat Synchronization Methods for Replacement Heifers
Producers that plan to use artificial insemination as part or all of this upcoming spring breeding season should start their preparations immediately. A popular synchronization protocol for heifers involves the feeding of an additive, and the feed must be ordered and delivered at the proper time. Melengestrol acetate (MGATM Pfizer Animal Health) is a feed additive commonly used in heifer feedlot rations to block the cycling activity of heifers. Melengestrol acetate is a synthetic progestin that has "progesterone-like" activity. When fed for a short period of time and then removed from the diet, the sudden absence of the progestin tends to allow a large percentage of cattle to exhibit heat together. Compared to normal heats, fertility at this first heat after MGATM removal has been reduced. Subsequent heats have returned to normal fertility. Armed with this knowledge, researchers have outlined an estrous synchronization protocol using MGATM and a prostaglandin injection. This program calls for the feeding of melengestrol acetate at the rate of 0.5 milligrams per head per day for 14 days. After 14 days, MGATM is removed from the feed. Most of the heifers will then exhibit heat over the next 8 days. Nineteen days after the MGATM feeding has stopped, each female is injected with prostaglandin to interrupt the next cycle. One to six days later, females are bred following detected standing heat. (See time line below). Research at several experiment stations has indicated that this method has induced some non-cycling replacement heifers to begin cycling, thereby increasing the percentage of those cattle bred early in the insemination season.
An important consideration is that the MGATM/prostaglandin synchronization program must be started 34-37 days before the start of the breeding season. This means that prior planning must be done to assure that the feed containing MGATM is prepared and ready to feed five weeks before the date of the first breeding. This synchronization method is designed to work best with replacement heifers.
Day 0 Start MGA
Day 14 End MGA
Day 33 Inject Prostaglandin
Day 34-40 Heat detect and breed.
