Anatomy And Physiology Of Farm Animals

ANATOMY

Anatomy is the study of the structure of different organs of the body of an animal

PHYSIOLOGY

Physiology deals with the functioning of these organs in the body of an animal.

A good knowledge of anatomy and physiology is a good insurance in management of farm animals.

ANIMAL REPRODUCTION TERMS

1.   Heat period: it is a period of desire when female animal receives the male

Characteristics

a.    Reddening or swollen vulva

b.   Slimming discharge from the vulva which at times may be mixed up with blood

c.    Frequent urination

d.   Wagging of trail

e.    Restlessness

f.     Mounting and being mounted

2.    Mating:  Mating is the coming together of male and female animals in sexual intercourse

3.   Service:  It is a term used to describe mating in cattle, sheep, goat and pig. In fowl topping is used. Treading is used in duck.

4.   Heat Repeat: This is when an animal comes on heat at specific interval depending on the type of animal if not served or service does not hold.   

5.   Heat Return: This is when an animal comes on heat 3 to 4 weeks after parturition.

6.   Parturition: is the act of giving birth to young one in farm animal. In cattle, it is called calving while in pig it is called farrowing in rabbit, it is called kindling.

7.   Lactation: it is a period of nursing and feeding the young one with breast milk

8.   Colostrums: it is the milk produced by the mother animal in the first to third day after parturition. It is yellowish in colour and has a sour taste.

IMPORTANT OF COLOSTRUM

a.    It has a laxative effect which allow the young one to pass out the first faeces know as foetal dung

b.   It contains antibiotic which gives the animals active immunity. An active immunity is the type of immunity that is built within the animal body. It is also called natural immunity. A passive immunity is the one built throughout the use of drug.

9.           Gestation period: It is the period between conception and birth or period between fertilization and birth. It is simply known as period of pregnancy.

Animals	Gestation period
Pig (sew) (female pig)	116 days (3 months 3 weeks 3 days)
Ewe (female sheep)	147 days
cow	283 days
Rabbit (doe)	1 month

10.        Oestrus cycle:  it is the interval from the end of one heat period to the beginning of another period

Animals	Oestrus cycle
cow	20-21 days
Ewe	17-21 days
Goat (doe)	17-21 days
Sew	14-28 day
Rabbit (doe)	Erratic

REPRODUCTION IN FARM ANIMALS

There are two types of reproduction:

a.    Sexual reproduction

b.   A sexual reproduction

Sexual reproduction

Sexual reproduction involves the coming together of male and female animal in sexual intercourse to produce an offspring and there are two groups of animals that are of agricultural importance. They are:

a.    Mammal

b.   Birds  

MALE REPRODUCTIVE ORGAN

The most important part of the male reproductive organs are the two test  which produce the spermatozoa. The spermatozoa is the male reproductive sex cell needed for fertilization. It is produced under a constant temperature of about 33-34⁰c. This spermatozoa becomes concentrated and matured after 7-9 days in the epidydimis. The epidydimis is the part of the man reproduction organ from where the sperm is transport through the sperm duct to the uterus masculinus for further maturity and ready for ejaculation.

The uterus masculinus and the bladder both opens in a common duct the urethra, this allows both urine and sperm to pass through. Other necessary sex glands are cowpers gland, prostate gland e.t.c They produce seminal fluid which mixes with the sperm to form semen. The fluid which mixes with the sperm to form semen helps to clear urine which is toxic to the sperm or the semen that can kill it. 

FEMALE REPRODUCTION ORGAN

This is different from male reproduction organ because it is located inside the body cavity except the vulva. The female reproductive organ consist of ovaries and tubular genitalia.

This later consists of fallopian tube, vagina, vestibule, vulva e.t.c

OVARIES

They produce the female reproductive cell (egg or ova). The production of eggs begins before birth but the appearance of ovary depends on egg, stages of reproductive cycle and the type of animal. The ovary remains in the cell until puberty when it begins to develop.

PUBERTY

It is a stage in animal development when physiological changes relating to reproduction begin to appear in female animal, such changes include:

1.   Egg development

2.   Ovulation

3.   Heat behavior e.t.c

In male animal, the changes include:

1.   Formation of spermatozoa

2.   Growing urge to meet female animal

3.   Development of necessary sex organs

REPRODUCTIVE HORMONES

Hormones are chemical substances produced by organs of the body of an animal and they help to speed up or hasten physiological processes, they include the following:

1.   Testoterone: It is produced by the seminiferrus tubular or the cell of the testes. This hormone stimulates the development of male secondary sexual characteristics. It also helps in the transportation of spermatozoa, protein synthesis and nitrogen retention.

2.   Oestrogen: It is produced by the follicle formed by germinal epithelium of the ovary. It also stimulates the formation of female secondary sexual characteristics. It also increase blood supply and water content in the uterus. It increases the secretion of mucor in the whole reproductive tract. It also stimulates the growth of mammary gland.

3.   Oxytoxin: Oxytoxin promotes the sperm transportation in the female reproductive tract. It also helps in the contraction of wall of the uterus at labour. It can also help in the release of milk from the mammary gland.

4.   Relaxin: Relaxin is produced by the ovary and it causes the relaxation of the pelvic ligament at the time to parturition.

5.   Luteinizing hormoene: It causes the rapture of the follicle and subsequent release of ova that is ovulation. It also stimulates the secretion of hormones such as oestrogen and progesterone.

6.   Progesterone/pregnancy hormone: It ensures the development of the uterus and implantation of the fertilized ovum. It causes the development of the alveoli in the mammary gland. It ensures the continuity of the pregnancy.

Assignment

1.   State five similarities between reproduction in birds and mammals

2.   In a tabular form, state five differences each between the reproduction in birds and mammals.          

Process of Reproduction

          There are three types of mating:

1.   Pasture Mating: Pasture mating is done at random in the field as the need arises.

2.   Hand Mating: It is a type of mating that is controlled

Pasture mating and hand mating are examples of natural mating.

3.   Artificial insemination: This involves the introduction of semen into the reproductive tract of a female animal by man with a special instrument called inseminator.

ADVANTAGES

i.             It is cheaper to import semen or sperm than the male animal

ii.           The sperm collected can be used to fertilize many female animals of various sizes

iii.          It is more economical as it reduces the cost of feeding and management of male animal

iv.          Sperm or semen can be used over a long time even after the death of the male animal

After mating, fertilization occurs half way down the oviduct. Fertilization is the fusion or union of male and female gametes to form a zygote. Thereafter, the zygote enters the uterus and attaches itself to the wall of the uterus. This is called IMPLANTATION. By this time, zygote has developed into an embryo consisting of the number of cells which later arrange themselves into:-

i.             The endoderm

ii.           The mesoderm

iii.          The ectoderm

These differentiated cells undergo rapid cells division to form the tissues and organs of the body

1.   The Ectoderm: The ectoderm develops to form the skin and the nervous system.

2.   The Ectoderm: The mesoderm develops to form the muscles, blood, bone and connecting tissue.

3.   The Ectoderm: The endoderm develops to form the gut or alimentary canal. This development will continue until a new individual is formed. The new embryo will be enclosed inside a membrane called amnio that contains amniotic fluid the amino is in turn surrounded by a membrane called chorion. The urinary bladder enlarges to form the allantois that is filled with the urine of the foetus. This membrane allows or keeps the temperature of the foetus warn and prevent mechanical injury.

FEEDING OF THE EMBRYO

The placenta through the umblical cord form a link between the mother and the developing embryo. Dissolved food nutrients from the mother’s blood diffuse through the placenta to the developing embryo. The oxygen in the mother’s blood also diffuses into the blood circulatory system of the foetus. The oxygen is then used inside the cells to break down food substances to release energy for the use of the embryo or of the foetus. The resultant waste product of the metabolism diffuses back into the mother’s blood where they are eliminated.

ABORTION

If the foetus is ejected before completing its development an abortion or premature birth is said to have occurred.

PARTURITION

Parturition marks the end of pregnancy and it is the release of young animal from the mother’s womb to the outside world or the act of giving birth to an offspring. The preparatory stage is called labour and the following are signs of  approaching parturition:

1.   Restlessness

2.   Pain

3.   Sagging under (flapping breast)

4.   Secretion of milky fluid by the mammary gland

5.   Redness and enlarged vulva

6.   Animal seek seclusion

The wall of the abdomen and the uterus contracts to force the foetus and placenta against the cervix thereby breaking the water bag. As this contraction continues the foetus is expelled through the birth canal and it is followed shortly after wall by the placenta.

EGG FORMATION

          Unlike mammal, hen has one functioning ovary. The organ in which egg is formed is called ovary and the oviduct. A typical ovary is situated at the left hand side of the body of a hen. Ovary can be seen as a yellowish clusters of cell of various sizes, have the shape of a grape. Each ovum is attached to ovary by a slender stalk that is called follicle stalk and enclosed in a thin membrane called vitallile. The ovum and its vitallile membrane are in turn enclosed in a thin envelop called follicle.

MECHANISM OF EGG FORMATION

As a result of external stimuli the anterior and posterior section of the pituitary gland are stimulated to produce three hormones namely:

1.    Follicle stimulating hormone

2.   Luteinizing hormone

3.   Lactogenic hormone

FOLLICLE STIMULATING HORMONE

1.       It causes growth and maturation of the ovary

2.       Luthelisign hormone: It causes ovulation in birds

3.       Lactogenic hormone: It causes broodiness

During ovulation, the yoke rupture along the line where there is no blood vessel called suture line or stigma. The yoke is grabbed by the mouth of the oviduct and passes through the rest of the oviduct by a peristaltic action of the wall of the oviduct. If the hen had previously mated, sperm cell will be present in the oviduct and fertilization takes place in the funnel region.

As the yolk passes through the oviduct various parts of the egg are added as follows:

1.   Magnum: in the magnum, the yolk spends three hours and in the magnum it acquires the mass of thick white or albumen which makes up about half of the total egg. Chalaza is also acquired in the magnum.  

2.   Isthmus: This is where the egg membrane is secreted and the shape of the egg is determined in the isthmus.

3.   Uterus (Shell gland): The yoke spends 18-20hrs in the uterus and this is where it spends the longest time at the end the remainder of the white egg (albumen) is added. The egg is also shelled up. Pigment is also secreted and bloom which is the moist antisceptic substance covering newly laid egg.

4.   Vagina: In the vagina the egg spends between 10-15 minutes before it is passed into the rectum where bacteria action is prevented. From the rectum it is passed on the cloaca where the egg is expelled and laid through the vent.

MAMMARY GLAND

          The mammary gland differs in farm animals, for example: there are glands in sheep and goat, four glands, in cattle and twelve to thirteen gland in pig, dog and rat. A fully matured udder is covered outside by skin and consist of the component parts.

1.   Alveoli: In the alveoli, the milk is synthesized and secreted and it is also called the store house of milk.

2.   Duct system: This is the passage way of milk and the milk is ejected from the alveoli when the cell is contracted.