Reproduction in Farm Animals

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In today’s class, we will be talking about reproduction in farm animals. Enjoy the class!

Reproduction in Farm Animals

Reproduction is the process that gives rise to young in farm animals; it is the ability of animals to birth young. This process starts when the animal is sexually matured. Time of sexual maturity varies between animals, in cattle, it takes up to 15 months, in goat and sheep about 6 months, poultry about 18 weeks etc. The following terms are associated with reproduction in farm animals.

• Oestrus cycle:

This is the interval from the end of one heat period to the beginning of another. It is under the influence of a hormone called oestrogen. It is the sexual cycle that occurs in all-female animals if the animal is not pregnant. The period varies among farm animals:

Cow: 20 – 21 days

Ewe: 17 – 21 days

Sow: 14 – 28 days

Doe (goat): 17 – 21 days

Doe (rabbit): spontaneous

• Ovulation:

This is rupturing of the ovarian wall to release an egg into the fallopian tube in farm animals; a process is controlled by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). It varies among farm animals.

Cow => 10 – 14 hours

Ewe => 20 – 24 hours

Sow => 24 – 36 hours

Doe (goat) => 12 – 36 hours

Doe (rabbit) => spontaneous

• Heat period:

This is the period in which female animals have the urge to copulate or accept the male animal. The female show signs of readiness to mate. It is controlled by oestrogen. It varies among farm animals

Cow => 5 – 24 hours

Ewe => 35 – 36 hours

Sow => 40 – 48 hours

Doe (goat) => 40 – 50 hours

Doe (rabbit) =>spontaneous

Signs of heat in farm animals

1. Restlessness
2. Mucus secretion by the cervix
3. Swollen and reddened vulva
4. Loss of appetite and frequent urination
5. Viscous secretion comes from the vagina and these arouse and excite the males
6. Abnormal body temperature
7. Grunting
8. Frequent urination
9. Standing still to be mounted on

In summary, ovulation (release of eggs) then heat period (receptivity to mating) then oestrus period (the preparatory period for next ovulation)/pregnancy if there is successful mating that leads to fertilization.

• Mating:

This is also called coitus or copulation (sexual intercourse). This is the act in which the penis of the male animal is inserted into the vaginal of the female animal leading to the introduction of sperm into the vagina. Mating could be natural or artificial.

Natural mating

It occurs when a male after identifying a female on heat, mates with the female animal. Examples of natural mating include:

• Flock mating:

This is a deliberate act in which the male and female animal is allowed to move together

Advantages flock mating

1. All animals have the freedom to participate in sexual intercourse
2. The farmer is saved the labour and cost of monitoring breeding
3. All-female may be mated because the number of males is widely spread

Disadvantages of flock mating

1. A female may be mated by more than one male thereby paternity becomes a difficult thing to determine
2. Two female may be on heat at the same time, thereby leading to the mating of only one of them.

• Pen mating:

This form of mating occurs in pigs and poultry. A male is given a specific number of female depending on the strength of the breed. About 1 male to 20 females on heat.

Advantages of pen mating

1. In poultry female eggs can be produced
2. There is a tendency of servicing female on heat

Disadvantages of pen mating

1. The spread of venereal diseases may be rampant
2. A deformed male may not be able to mate

• Stud mating:

A male (stud) with proven qualities is kept in a room in this type. Any female that is on heat is led to it for mating and thereafter the female is removed.

Advantages stud mating

1. The paternity of the offspring can be identified
2. It is a good system of upgrading the breed because the only male with both proven quality is used.

Disadvantages stud mating

1. The spread of venereal diseases may be rampant.
2. It takes a lot of expertise to practice.

• Artificial mating:

This is called artificial insemination, which involves the act of inserting the spermatozoa artificially into the vagina of female animals on heat. The sperm is collected from a male animal with desired characters with the aid of an artificial vagina, massage method, etc. Sperm collected is stored in liquid nitrogen at -196°C.

Advantages of artificial mating

1. The semen can be used over a long time even after the death of the male animal.
2. It is more economical as it reduces the cost of feeding and managing male animals.

Disadvantages of artificial mating

1. It requires expertise which may not be readily available.
2. Difficulty in detecting female animals on heat may limit success.

• Fertilization:

This is the fusion of the male and female sex cells spermatozoa and ovum respectively. This process occurs in the Fallopian tube or oviduct.

• Implantation:

This is the attachment of zygote (fertilized egg) to the wall of the uterus after fertilization. The zygote develops into a foetus and continues to grow till the time of parturition.

Gestation period

This is a period between fertilization of an ovum to the birth of young ones, conception and

birth. During gestation, female animals do not come on heat. It is under the control of hormone called progesterone (Pregnancy hormone).

 Features of the gestation period

1. There is swelling of the abdomen
2. There is swelling of adder
3. There is an increase in body weight

SPECIES	NAME OF FEMALE	GESTATION PERIOD
Horse Cattle	Mare Cow	336 days 283 days
Goat	Doe	150 days
Sheep	Ewe	150 days
Pig	Sow	114 days
Rabbit Chicken	Doe Hen	31days 21 days

Parturition

This is the act of giving birth in farm animals. It marks the end of pregnancy and the beginning of lactation. The act of parturition for each animal is unique.

Cow: Calving

Sow: Farrowing

Ewe: Lambing

Goat (Doe): Kidding

Rabbit (Doe): Kindling

Poultry: hatching

Signs of approaching parturition

1. Mammary glands enlarge and begin to secrete milk substance
2. Vulva swells and becomes soft.
3. There may be thick mucus discharge
4. The animal becomes restless lies down and gets up frequently
5. The animal urinate frequently
6. Loss of appetite
7. The animal tries to build a nest and beds e.g. in rabbit

Lactation

This is the period during which the female releases milk from its udder immediately after parturition and thereafter. Lactation is under the control of hormone called oxytocin, it can be increased by injecting the animal with oxytocin.

Lactation is also be stimulated by the presence of the young ones, presence of a milker, the use of hand to rub the udder and the use of a machine to milk the cow. The milk from goat is the best and richest of all the animals. Milk collected from animals is made fit for consumption via a process known as pasteurization.

• Colostrum:

This is the milk produced immediately after parturition within the first five days of milk production is essentially colostrum. It is yellowish-white milk. The newborn animals need to take colostrum because

1. It contains some anti-biotic against diseases to which the mother has been exposed.
2. It enables the newborn to get immunity against diseases
3. It is rich in protein especially albumin and globulins
4. It is rich in vitamins.
5. It is highly digestible and has a laxative effect which helps the young ones to expel the faeces.

General evaluation

1. What is reproduction in farm animals?
2. What is implantation?
3. Lists five signs of approaching parturition
4. Why is colostrum important for the newborn animals?

Theory

1. Write a short note on the development of an embryo.
2. Describe the right positioning of a lamb before expulsion.

 

In our next class, we will be talking more about Reproduction In Farm Animals.  We hope you enjoyed the class.

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