Progesterone administration in planned reproduction of cattle

IGNACIO M. HELBLING; DR. JULIO A. LUNA

International Journal of Medical and Biological Frontiers

Nova Science Publishers, Inc.

Lugar: New York; Año: 2017 vol. 23 p. 31 - 71

1081-3829

Cattle constitute one of the most widely used species for animal husbandry. The growing demand for products derived from cattle has led to the development of intensive production systems. These systems require planned breeding of the herd to maintain optimal production levels. Planned breeding involves estrous cycle control and artificial insemination to assist reproduction. Estrus control is a hormonal treatment that can be performed by following different protocols with the aim of manipulating the reproductive cycle to synchronize estrus in females. Estrus synchronization presents several advantages mainly related to the avoidance of estrus detection and facilitates overall planning, including logistics of artificial insemination, grazing and specific nutrition programs, calving dates, and vaccination schedules. Progesterone plays a major role in estrus cycle control programs. Progesterone blood level regulates secretion and patterns of different estrus-inducing hormones and controls follicle and corpus luteum growth and development. Hence, one of the most important step for cycle regulation is the control of blood progesterone concentration at required time periods. Typically, the reproductive management strategy includes the administration of an exogenous source of progesterone to the animal, releasing the hormone at controlled rates to maintain the concentration at supraluteal levels for a specific period of time. When delivery is disrupted, progesterone concentration falls below the threshold to subluteal levels, inducing the beginning of a hormonal-regulated mechanism which will lead to the onset of heat and subsequent ovulation. Several technologies have been developed for progesterone administration. The most widespread practice is the use of matrices for sustained administration. These matrices are made of polymeric materials and contain the hormone. These polymeric matrices can be manufactured with different geometric shapes and can be placed in different sites of the animal body. Today, intravaginal administration is the main route of administration. Intravaginal devices made of non-biodegradable polymers are the most widely used systems for synchronization purposes. However, some concerns about the nonbiodegradable materials that make up these intravaginal devices and other related inconveniencies promote new research lines. There is a general trend towards simplifying