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Prostaglandins Do Not Induce Heat or Make Them Stronger

Reproductive success comes in the form of knowledgeable people

NEW YORK (April 16, 2008) - The dairy industry has recently seen a renewed focus on prostaglandins (PGF₂α) and how they affect the reproductive programs implemented at the dairy level. Estrus synchronization programs transformed reproductive management in the dairy industry several decades ago, and prostaglandins have played a big part in those programs for more than 20 years. However, there are some misconceptions about how this hormone works within a cow’s reproductive system and how they affect overall reproductive performance and success.

First, to help clarify the headline of this article, please note that PGF₂α does not directly induce estrus behavior, or heat. It stimulates the events that eventually lead to heat.

Understanding the physiology behind a cow’s reproductive system, what roles hormones play in both physiology and synchronized breeding programs, and how to best manage such programs is the key to successful reproductive performance. The bottom line: knowledge is power.

Fred Moreira, DVM, senior veterinarian, Pfizer Animal Health , outlines below the most important basics to understanding how PGF₂α works and its role within a dairy’s reproductive management program.

1. PGF₂α triggers luteolysis, not heat

The most important function of PGF₂α is luteolysis, which is the regression of the corpus luteum (CL). The CL is a gland formed after ovulation on the cow’s ovaries that secretes the hormone progesterone. While progesterone is being secreted by the CL, cows cannot come in heat. Before cows come in heat, it is necessary to eliminate the CL, which is the function of PGF₂α products. When PGF₂α is injected, it triggers a cascade of events that will eventually lead to CL regression. This cascade involves the hormone Oxytocin, which is present at low concentrations in the CL, and the cow’s own PGF₂α, which is produced by the uterus. Both Oxytocin and the cow’s own PGF₂α are what ultimately lead to complete CL regression.

2. There are multiple hormones at work

As the CL regresses, ovarian follicles are then able to grow and secrete Estradiol, an estrogen-like hormone. Estradiol secretion increases because it is not competing with progesterone. Estradiol is the one hormone that will reach behavioral centers in the brain and induce estrus behavior. Hence, it is Estradiol, not PGF₂α, which induces heats.

3. A prostaglandin is a prostaglandin

Based on the way PGF₂α works and on the results of independent scientific study from the past 25 years, PGF₂α products cannot be differentiated by their ability to induce CL regression and affect heat intensity and duration.

Reproductive solutions come in the form of reproductive program execution, as well as the expertise you gain from working with your veterinarian or animal health support team, not the type of prostaglandin you use.

Producers have a PGF₂α choice

Because there is no difference in efficacy among products, a PGF₂α purchase is typically based on three things:

1. Price

2. Availability

3. Added value

When making a choice on PGF₂α, veterinarians and producers have to consider how much weight to assign each of the three considerations. When they buy LUTALYSE (dinoprost tromethamine) Sterile Solution, for example, producers get the technical and field support, educational programs, research support and breeding program assistance from Pfizer Animal Health .

At the end of the day, producers don’t just want a PGF₂α. They want more pregnant cows. With the support of the largest field force in the industry, they can get there with LUTALYSE, the leader in the industry for over 30 years. In fact, more than 90 percent of reproduction research performed is funded by Pfizer Animal Health on behalf of LUTALYSE, in order to find solutions for customers.

As with all parenteral products, aseptic technique should be used to reduce the possibility of post-injection bacterial infections. Do not administer in pregnant animals unless cessation of pregnancy is desired. Not for intravenous administration. Women of childbearing age and persons with respiratory problems should exercise extreme caution when handling this product. For more safety information, please refer to the LUTALYSE prescribing information.

The Pfizer Animal Health Dairy Wellness Plan is a 365-day approach to managing your dairy operation that focuses on the health of the dairy animal, the economic health of the dairy and the proper use of animal health products leading to a safe and healthy food supply.

Pfizer Inc. (NYSE: PFE), the world’s largest research-based pharmaceutical company, is a world leader in discovering and developing innovative animal vaccines and prescription medicines. Pfizer Animal Health is dedicated to improving the safety, quality and productivity of the world’s food supply by enhancing the health of livestock and poultry; and in helping companion animals live longer and healthier lives. For additional information on Pfizer’s portfolio of animal products, visit www.PfizerAH.com.

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