REPRODUCTION IN FARM ANIMALS

Reproduction is the process that gives rise to young in farm animals; it is the ability of animals to give birth to young. This process starts when the animal is sexually mature.

Time of sexual maturity varies between animals; in cattle, it takes up to 15 months, in goat and sheep about 6 months, in 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 the rupture of the ovarian wall to release an egg into the fallopian tube in farm animals; a process that 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 with or accept the male animal. The female shows 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 (preparatory period for next ovulation)/pregnancy if there is successful mating that leads to fertilisation.

 

EVALUATION

1. Differentiate between the oestrus cycle and the heat period.
2. List the duration of ovulation in cow, pig, goat and rabbit.

 

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 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 animals are allowed to move together

ADVANTAGES OF FLOCK MATING

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

DISADVANTAGES OF FLOCK MATING

1. A female may be mated by more than one male, thereby making paternity difficult to determine
2. Two females 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 to service females in 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 in 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 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.

 

DISADVANTAGESOF ARTIFICIAL MATING

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

 

EVALUATION

1. Explain briefly the term artificial mating.
2. Mention two advantages and two disadvantages of artificial mating
3. State two ways of collecting semen from male animals.
4. Differentiate between ovulation, heat period and oestrus cycle
5. List five signs of heat in animals.

 

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 the zygote (fertilised egg) to the wall of the uterus after fertilisation. The zygote develops into a foetus and continues to grow till the time of parturition.

 

GESTATION PERIOD

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

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

 

FEATURES OF GESTATION PERIOD

1. There is swelling of the abdomen
2. There is swelling of the 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, sits down and gets up frequently
5. The animal urinates frequently
6. Loss of appetite
7. The animal tries to build a nest and beds, e.g. in a rabbit

 

EVALUATION

1. Write a short note on: i) Gestation, ii) Parturition
2. State five signs of parturition in farm animals.
3. What name is given to parturition in a) Sheep b) Cattlec) Pig

 

LACTATION

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

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

 

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 antibiotics 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 newborn animals?

 

WEEKEND ASSIGNMENT

1. The interval from the end of a heat period to the beginning of another is ____
2. ovulation B. anaestrus C.oestrus cycle D. implantation
3. The following are influenced by oestrogen hormone except A. lactation, B. ovulation C. oestrus, D. heat
4. Natural mating predisposes animals to ____ diseases: A. cholera, B. venereal, C. malaria D. dounch
5. A male animal with desirable characters kept mainly for mating is called a ____. stud C. bull C. heifer
6. The gestation period of a pig is A. 150 days, B. 114 days, C. 32 days, D. 280 days

 

THEORY

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

 

See also

RESPIRATORY SYSTEM

ANATOMY AND PHYSIOLOGY OF FARM ANIMALS

FARM MECHANIZATION

FARM POWER

SIMPLE FARM TOOLS