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 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 ovarian wall to release 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 (preparatory period for next ovulation)/pregnancy if there is successful mating that leads to fertilization.

EVALUATION

1. Differentiate between oestrus cycle and 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:

1. FLOCK MATING

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

ADVANTAGES FLOCK MATING

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

DISADVANTAGES FLOCK MATING

1. A female may be mated by more than one male thereby paternity become 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 PEN MATING

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

DISADVANTAGES PEN MATING

1. The spread of venereal diseases may be rampant
2. 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 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 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 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 sign 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 zygote (fertilized egg) to the wall of the uterus after fertilization. The zygote develops into a foetus and continues to grow till 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 GESTATION PERIOD

1. There is swelling of abdomen
2. There is swelling of adder
3. There is 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 become soft
3. There may be thick mucus discharge
4. The animal become restless lies down and get 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

EVALUATION

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

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 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 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. It is important for the new born animals to take colostrum because

1. It contain some anti-biotic against diseases to which the mother has been exposed.
2. It enables the new born 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 feaces.

READING ASSIGNMENT

• Essential Agricultural Science for Senior Secondary Schools by O. A. Iwena pages 281 – 288.
• Essential Biology for Senior Secondary Schools by M. C. Micheal pages 337– 344.
• Answer the following questions from WAEC PAQ 2007 theory question 7, 2016 theory question 4 and 5c,  1991 theory question 7, 1994 theory question 7 and 2015 theory question 4b

GENERAL EVALUATION

1. What is reproduction in farm animals?
   1. What is implantation?
   1. Lists five signs of approaching parturition
   1. Why is colostrum important for the new born animals?

WEEKEND ASSIGNMENT

1. The interval from the end of a heat period to the beginning of another is ____

A. ovulation B.anaestrusC.oestrus cycle D. implantation

• The following are influence by oestrogen hormone except A. lactation B. ovulation

C.oestrusD. heat

• Natural mating predisposes animals to ____ diseases A. cholera B. venereal C. malaria

D.dounch

• A male animal with desirable characters kept mainly for mating is called a ____

A.dounchB. stud C. bull C. heifer

• The gestation period of a pig is A. 150 days B. 114 days C. 32 days D. 280 days

THEORY

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

PROCESSES OF EGG FORMATION IN POULTRY

The egg in poultry is partly formed in the ovary and in the oviduct. At ovulation the ovum carrying the yolk is released by the ovary into the oviduct through the funnel called infundibulum. Fertilization takes place in the infundibulum where the egg spends 15 minutes and moves into the magnum. In the magnum, part of the egg white (albumen) and the chalaza are secreted round the yolk. The egg stays for 3 hours in the magnum and moves into the isthmus where the two shell membranes are formed. The egg stays for 1 hour 15 minutes in the isthmus and moves into the uterus where it remains for 18 – 21 hours and the egg shell is formed from calcium carbonate. Mineral solutions are also added to the egg before it moves into the vagina whereit remains for 1 – 15 minutes before it is laid through the cloaca. A complete formation of eggs takes almost 26 hours.

EVALUATION

1. Describe the processes of egg formation in poultry.
2. Describe the reproductive system of poultry birds.

MALE AND FEMALE REPRODUCTIVE HORMONES

Hormones are organic chemical substances produced by endocrine (ductless) glands which

influence growth, development and metabolic activities in farm animals. These include

HORMONE	SEX	SITE OF SECRETION	FUNCTIONS
Testosterone/ Androgen	Male	Testes	It stimulates the development of secondary sexual characters in male. It stimulates sperm production through spermatogenesis.
Oestrogen	Female	Ovary	It stimulates the development of secondary sexual characteristics in female animals It promotes the production of ova or eggs through oogenesis. It stimulates mammary gland development
Progesterone	Female	Corpus luteum	It ensures uterus development and implantation of the fertilized ovum. It inhibits oestrus i. e. prevents ovulation. It stimulates the development of mammary gland It ensures the continuance of pregnancy.
Oxytocin	Female	Pituitary	It aids the contraction of the uterine wall during parturition. It promotes milk let-down after parturition. It aids sperm transportation in the vagina.
Relaxin	Female	Pituitary	It aids relaxation of pelvic ligaments during parturition.
Follicle stimulating hormone (FSH)	Female	Pituitary	It stimulates the growth of ovarian follicle.
Luteinizing hormone	Female	Pituitary	It stimulates the secretion of oestrogen and progesterone. It causes the rupture of the follicle and the release of the ova from the follicle.

GENERAL EVALUATION

1. List five animal hormones and function.
2. What are the functions of the following in the processes of egg formation in poultry?
3. Ovary
4. Oviduct
5. Magnum
6. uterus

READING ASSIGNMENT

• Essential Agricultural Science for Senior Secondary Schools by O.A. Iwena chapter 30 page 288 – 290.
• Answer the following questions from WAEC PAQ 2015 theory question 4a

WEEKEND ASSIGNMENT

1. Which of these is not a part of the male reproductive system A. uterus masculinusB. oviduct C. testes D. vas deferens
2. The following except one are female reproductive hormones A.oestrogenB. progesterone C. testosterone D. oxytocin
3. Fertilization in poultry birds takes place in the A. infundibulum B. isthmus C.magnumD. uterus
4. The following except one are viviparous animals A. pig B. cattle C. turkey D. goat
5. The hormone responsible for the contraction of the uterine wall during parturition is known as A. oxytocin B. progesterone C. luteinizing hormone D.relaxin

THEORY

1. Draw and label the diagram of an egg.
2. List five reproductive hormones, site of secretion and their functions.