All farm animals reproduce sexually. In the testes of males and ovaries of females, germ cells mature. The sex glands form hormones, under the influence of which secondary sexual characteristics appear in animals and male and female genital organs develop.
The male genital organs include the testes, appendages of the testes, vas deferens, testis sac, urogenital canal with the penis and accessory genital glands of various structures and functions.
Male germ cells ripen in the testes – spermine, which then enter the vas deferens system. An outpouring during sexual intercourse of seminal fluid is called ejaculation. The volume and quality of the ejaculate depend on the species characteristics of the animal, its physiological state, as well as on the feeding conditions. During copulation, sperm is introduced into the female genital organs by ejaculatory contractions of the male genital tract. It enters either the vagina or the uterus.
For the female genital organs are the ovaries, fallopian tubes, uterus, vagina. In the ovaries, the female reproductive gamete-egg cells mature. Ovarian hormones cause the development of female sexual characteristics (mammary glands, etc.).
With the onset of puberty, females periodically appear estrus. During estrus in the female, the external genitalia redden and swell. The mucous membrane of the uterus and vagina swells and secretes mucus.
Ovulation (rupture of the follicle and the exit of the egg), as a rule, occurs in the second half of the hunt or before its end. After ovulation, the egg remains capable of fertilization for 5-10 hours. Spermine can retain fertility for 1-2 days. The shorter the time between mating and ovulation, the greater the chance of fertilization. Both too early (before ovulation) and too late (after ovulation) insemination does not lead to fertilization. In chickens, fertilization can occur 32 days after mating.
When mating, semen is poured into the female genital tract. Spermine enters the oviduct, where the egg is fertilized. The resulting zygote (a fertilized egg in which the hereditary information of the father and mother is combined) passes through the oviduct into the cavity of the uterine horn, where the embryo and then the fetus develop from it. If fertilization has not occurred, then after a certain time, sexual hunting again sets in. It is repeated in mares on average in 20-23 days, in cows in 18-21, in sheep in 17, in pigs in 19-21 days. The time from the beginning of one sexual hunt to another is called the sexual cycle.
The ability of farm animals to reproduce is one of the main indicators that determine their economic value.
The movement provides the movement of the animal organism in the external environment, is carried out by the apparatus of movement in conjunction with the cardiovascular and nervous systems.
Growth and development (in ontogenesis – from the beginning of its inception and throughout life, in phylogenesis – the historical development of organisms of a certain type) are processes in which all body systems participate.
Heredity – the transfer of genetic traits from parents to offspring is carried out by the genes of the chromosomes of cells in which protein synthesis is encoded for each individual individual.
Variability – a change in the basic genetic properties of the body in connection with changes in the environment, the acquisition of new, useful qualities for the body in the process of evolution of the animal world and their fixing by inheritance.
Adaptation – adaptation to the conditions of existence, a necessary condition for life. Thus, each organism is inextricably linked with the surrounding nature, cannot exist outside of it and is a part of living matter. The animal as a mechanical system is not isolated, and gravity acts on it.
The structure of the animal. V. Ya. Brovar (1960) established a connection between the structure of the animal and the system of gravity of its body, making cuts (dissection) of the body of young cattle through the common center of gravity and the centers of gravity of each individual part (Fig. 2).
In the area of the general center of gravity lies the liver, the structure of which is more tender and less durable compared to other organs. With any movements of the animal, it is located at the point of relative rest of the body. In the same area is the solar plexus and the celiac artery departs. The heart lies in the center of gravity of the anterior half of the animal’s body, and the kidneys lie in the back, therefore, these organs are located at the points of relative peace, but of the next order in comparison with the liver.
Fig. 2. The layout of the general and partial centers of gravity of the body of the animal (according to V. Ya. Provar):
- 1 – cut through a common center of gravity into the front and rear halves;
- 2 – cut through the center of gravity of the anterior half of the body; 3– cut through the center of gravity of the posterior half of the body; 4, 5, 6,7 – cuts through the centers of gravity of each quarter of the body. As a result of cuts through centers of gravity, they separate
head, neck, sacrum and tail
The direction of the body’s gravity, determined by sequential decomposition of the resultant entire system, coincides with the anatomical boundaries dividing the axial skeleton of the mammal into its natural parts (skull, cervical, thoracic, lumbar, sacral and caudal) (Table 1, Fig. 3 )
The division into parts of the severed limb by horizontal planes through its centers of gravity coincides with the anatomical division of the limb into natural departments – belts and free limbs.
For a more accurate indication of the location of a particular organ or part of the body in the body, planes and directions are distinguished (the head of the animal should be so that the forehead is in the same plane with the back).
Mentally draw the following planes: vertical – sagittal, as well as frontal and horizontal – segmental (Fig. 4).
Sagittal planes cut the body of the animal from top to bottom on the right and left parts, and only one of them – the middle sagittal plane – divides the body of the animal into equal symmetrical (right and left) halves; lateral sagittal planes divide the body of the animal into unequal and asymmetric parts.
The frontal planes dissect the body into the upper, or dorsal, and lower, or abdominal parts.
Segment planes are carried out in the transverse direction and divide the body into transverse segments, or segments.
To better clarify the position of the body and the direction of its parts, the following topographic terms are used; dorsal – directed in animals along the back (up); ventral – to the stomach (down); medial – inside; lateral – outward; cranial – to the head; caudal – to the tail (for the head: oral – to the mouth, aboral – from the mouth); proximal to the axial part of the body; distal – from the axial part of the body; dorsal (on the limbs) – to the back (front) surface of the limb; palmar (volar) – to the anti-back (back) surface of the thoracic limb and plantar – to the anti-back (back) surface of the pelvis.
When the animal’s body is divided into anterior and posterior halves in a segmental plane of a common center of gravity, the cut plane passes through the body of the 11th thoracic vertebra and the liver. When the front half is divided, the cut plane lies between the last cervical and first thoracic vertebrae, then along the front edge of the ribs and through the shoulder joint and separates the neck from the chest.
When the posterior half is divided, the cut plane is located between the last lumbar and first sacral vertebrae, separating the lower back from the sacrum, then through the iliac wing, then through the abdominal cavity and cuts off the patella with part of the lower epiphysis of the femur, i.e. the cut passes through the knee joint .
Thus, the first quarter includes the head-cervical part, the second and third quarters (one lying in front of the plane of the common center of gravity, the other behind) – the sternum-lumbar part, and the fourth quarter – the sacral-tail part. Then, each quarter is sawn in the plane of their centers of gravity into the front and rear (eighth) parts. When the first quarter of the head-cervical part is divided, the cut plane passes through the occipital-atlant joint and divides it into two natural departments – the head and neck. When the second quarter is divided, the cut plane goes through the 5th thoracic vertebra and the heart, to the limbs – through the elbow and carpal joints. When the third quarter is divided, the cut plane passes through the 2nd lumbar vertebra, kidneys and colon.
Thanks to rotational movements, individual sections of the bones acquire a spherical shape. A. Ya. Bobrovsky studied the effect of rotational movements in the joints around their axes on bone formation.
The general laws of the structure of a living organism also include uniaxiality, metamerism and antimerism, due to the mobility of the animal.
There is one more regularity of the body structure: a brain tube runs along the back, and an internal tube runs ventrally from it. With the end of the growth and development of the body, the structures of the organs stabilize, and their interconnection, interdependence, interdependence and interaction not only remain, but also continue to develop and improve.