Pigs use B-ultrasound machines to observe the deposition of semen into the cervix of sows during mating or insemination. The contraction of the cervical muscles stimulates the ejaculation of boars and is the basis for their ejaculation response to the "glove" or "digital pressure" techniques used for semen collection.

During natural service, boars deposit 3 to 6 billion sperm, or during fertilization, they deposit 2 to 6 billion sperm, but only a small portion of these sperm reach the fallopian tubes and eggs. Although sperm are active, they do not push themselves through the female path. Sperm transport is caused by uterine contractions. These contractions are stimulated by oxytocin released by the pituitary gland. Its release is mediated by mating behavior and mating stimuli. Remember this when fertilizing sows or sows. Face to face contact with boars, combined with tactile stimulation during and after fertilization, can improve sperm transport. Sperm must exist in females 6-10 hours before fertilization can occur.

Fertilization or the union of sperm and egg occurs in the upper one-third of the fallopian tube. If females mate with fertile boars at the correct time relative to ovulation, the fertilization rate is almost 100%. About 2 days after fertilization, the blastocyst enters the uterus. They are in the 4-8 cell stage and begin to be evenly spaced in the middle of the uterine horn. At this stage, the blastocyst can be transplanted from one horn to another.

The crucial period of pregnancy is approximately 11-16 days after mating. pigs use B-ultrasound images to display the elongation and growth of blastocysts (2-3 feet), viscous masses that begin to adhere to the uterine wall. Due to attachment failure, there may be a significant loss in litter size during this development phase. On average, 17 eggs shed during estrus, but only about 12 are treated as blastocysts after attachment is complete. It is believed that certain factors can limit the number of attached blastocysts in a given uterus. Research has shown that overcrowding is not a major limiting factor. Embryo survival may be related to certain uterine secretions that are currently not clearly defined. Environmental stress factors such as high temperatures and combat caused by mixing or recombining animals can also have adverse effects on implantation and embryo survival. Usually, at least four blastocysts are required to continue pregnancy.

Pigs use B-ultrasound machines until the 25th to 35th day, and the embryo grows about 1 to 1 1/2 inches in length, with the main body systems and appendages forming well. Each embryo is surrounded by a series of independent membranes filled with fluid, including the amniotic and chorionic membranes that contain the placenta. These membranes help protect and nourish the growing embryo. Nutrients, waste, gases, and certain antibodies cross the membrane between the dam and the embryonic blood system. Detect the presence of this liquid using commonly used "ultrasound" pregnancy diagnostic equipment.

The fetal period of pigs using B-ultrasound machines starts around the 36th day. Gender can be easily determined through external examination, and the main systems of the body are more clearly defined. The fetus can now be referred to as a miniature adult. Fetal orientation is random; Some are head to head, some are tail to tail, and some are end-to-end. During childbirth, about half of the babies are born by the husband, and the other half are born first. Embryos that die before 35-40 days are usually reabsorbed by the dam. However, progressive calcification of the bones begins on day 36, and subsequent deaths will result in mummification.

By the 109th day of using a B-ultrasound machine, the fetus weighs approximately 1.5 to 2 pounds. Hair begins to appear, but remains trapped beneath the skin layer until near birth. During the entire pregnancy, the uterus gradually increases by about 2 to 3 pounds during mating, and gradually increased to 60 pounds last week, including fetal contents. Some females may lose up to 10% to 11% of their body weight during childbirth or delivery.

The average gestation period or time from conception to delivery for pigs using a B-ultrasound machine is 114 days. During pregnancy, piglets grow from the combination of microscopic sperm and eggs to a body weight of 3 to 3? A fully formed individual of a pound.

link: https://www.bxlimage.com/nw/385.html