What hormone is primarily responsible for maintaining pregnancy in dairy cattle?

The hormone primarily responsible for maintaining pregnancy in dairy cattle is progesterone. This hormone plays a crucial role during the reproductive cycle by preparing the uterine lining for the implantation of an embryo. Once conception occurs, progesterone is secreted by the corpus luteum, and later by the placenta, to maintain a suitable environment for the developing fetus. It helps to suppress further estrous cycles and prevents uterine contractions that could lead to the loss of the pregnancy.

Progesterone's function in supporting pregnancy is essential, as it ensures that the uterine tissue remains conducive to sustaining the embryo and ultimately allows for the successful development of the calf during gestation. Its levels need to be correctly maintained throughout the pregnancy to avoid complications.

While hormones like estrogen, oxytocin, and prolactin have roles in the reproductive system and lactation, they do not primarily maintain pregnancy. Estrogen is involved in the development of secondary sexual characteristics and induces estrus. Oxytocin is significant for milk ejection during lactation and can induce contractions during parturition. Prolactin primarily facilitates milk production and is more related to postpartum functions rather than the maintenance of pregnancy itself.