Fisiología reproductiva: Hembra bovina - Primera parte -

Summary

This video provides an in-depth explanation of the reproductive physiology of cows, focusing on the estrous cycle. It covers key aspects such as puberty, hormonal changes, and the different phases of the cycle: proestrus, estrus, metestrus, and diestrus. The script explains hormonal interactions, like the role of estrogen, progesterone, LH, and FSH, and the behavioral signs that accompany each phase. The video also highlights the process of ovulation, luteolysis, and how prostaglandin plays a crucial role in the reproductive cycle, along with its mechanism of transfer in cows. This knowledge is vital for effective reproductive management in cattle.

Takeaways

• 😀 Puberty in cows typically occurs between 12-18 months, depending on body weight, and is closely linked to the animal's nutritional state.
• 😀 Cows are polyestrous animals, meaning they cycle throughout the year, unlike some species that have seasonal breeding periods.
• 😀 The estrous cycle in cows lasts approximately 21 days and includes four main phases: proestrus, estrus, metaestrus, and diestrus.
• 😀 During proestrus, estrogen levels rise, leading to behavior changes such as mounting other cows (virilo behavior).
• 😀 Estrus is the phase of active mating acceptance, where high levels of estrogen make cows receptive to the male for about 16 hours.
• 😀 Metaestrus follows estrus and is characterized by the formation of the corpus luteum and rising progesterone levels.
• 😀 Diestrus is dominated by high progesterone levels, signaling that the cow is not in estrus, and this phase ends with luteolysis if pregnancy does not occur.
• 😀 Hormones like LH, FSH, and progesterone regulate the different phases of the estrous cycle through their interaction with the ovaries and the reproductive system.
• 😀 Luteolysis is a crucial process where the corpus luteum breaks down due to the action of prostaglandin F2 alpha, leading to the end of the diestrus phase and the start of a new cycle.
• 😀 The behavior of cows during the cycle, including their activity levels and mating behaviors, is directly influenced by the hormonal changes that occur during each phase.

Q & A

What is the average age at which cows reach puberty?

Cows reach puberty between 12 to 18 months of age, with the onset primarily dependent on their body weight, typically when they reach 30-40% of their adult weight.

How long does the estrous cycle of a cow typically last?

The estrous cycle of a cow typically lasts around 21 days.

What are the two main phases of the cow's estrous cycle?

The two main phases of the cow's estrous cycle are the follicular phase (Proestrus and Estrus) and the luteal phase (Metestrus and Diestrus).

What behavioral changes occur in cows during the Proestrus phase?

During the Proestrus phase, cows exhibit virile behaviors, such as mounting other cows, which is a sign of heightened sexual activity.

What role do hormones play in the Proestrus phase?

In the Proestrus phase, increasing levels of LH and FSH stimulate the production of estrogen in the ovaries, which leads to changes in behavior, including mounting activity.

How can you identify a cow in Estrus (heat)?

A cow in Estrus will show signs of being passive to the male, accept mounting, and exhibit physical signs like swollen vulva and clear vaginal discharge. This phase typically lasts around 16 hours.

What happens hormonally during Estrus in cows?

During Estrus, estrogen levels peak, which stimulates the release of a large pulse of LH, triggering ovulation. This is the time when the cow is most receptive to mating.

What is the significance of ovulation in the cow's estrous cycle?

Ovulation occurs after a peak in LH levels during Estrus and is crucial for reproduction, as it releases an egg that can be fertilized by the male's sperm.

What hormonal changes occur during Metestrus and what does this phase involve?

During Metestrus, the cow's body produces progesterone from the developing corpus luteum. Estrogen levels drop, and the cow may still exhibit some virile behavior, including mounting.

What happens during Diestrus in the cow's estrous cycle?

In Diestrus, the cow's progesterone levels remain high due to the presence of a mature corpus luteum, and the cow shows no signs of sexual activity. This phase continues until pregnancy is either confirmed or the cycle restarts.

How does prostaglandin F2α affect the cow's reproductive cycle?

Prostaglandin F2α causes luteolysis, or the degeneration of the corpus luteum, when pregnancy is not recognized. This leads to a drop in progesterone and allows the cycle to begin again.

Why is the interaction of prostaglandin F2α with the cow's circulatory system unique compared to other species?

In cows, prostaglandin F2α is transferred directly from the uterine vein to the ovarian artery, allowing it to target the corpus luteum more efficiently. This transfer mechanism is different from species like horses, where prostaglandin F2α circulates through the systemic circulation before reaching the ovary.