O Level Notes : Agriculture - Anatomy : The reproduction system

The productivity of farm animals is determined by level of nutritional ration. Animals can be given maintenance ration just for keeping them healthy without increasing the weight or causing production. Production ration is given to animals to produce products such as meat, milk and eggs. Feed formulations are made from farm produce which are mixed together to come up with desirable digestible protein concentration suitable for specific animals.

Reproduction in ruminants

Reproduction is a process whereby organisms multiply through producing offsprings. Ruminant animals have four chambered stomachs. Examples are cattle, goats and sheep. 

Reproductive system of a cow

When eggs are mature in the ovary, a hormone called oestrogen is produced under the influence of another hormone called the follicle stimulating hormone. Oestrogen is secreted by graafian follicles located in the ovary. It induces heat period that means the animal exhibits signs of heat and it is during this period that the ovum is released from the ovary. Ovulation (egg release) is stimulated by another hormone called the luteinizing hormone which is produced by the anterior pituitary gland. The hormone causes the rapture of the graafian follicles which release the ova. It also causes the growth of the corpus luteum in the cavity that is left after ovulation. After the ovum has been released from the ovary, it enters the infundibulum which is the opening of the oviduct (fallopian tube) and this is where fertilisation takes place. Later on, the egg moves down the fallopian tube towards the uterus where it implants itself until the calf is born. The gestation period of a cow is about 270 days. 

Other hormones associated with reproduction are:

Progesterone

It is secreted by the corpus luteum. It inhibits the release of luteinizing hormone and prepares the uterus wall to receive the fertilized egg. The progesterone hormone maintains pregnancy and causes uterine and mammary glands to grow. The hormone facilitates the secretion of uterine milk on which the foetus feeds and causes extensive growth of the alveoli (which manufacture milk) in the udder. 

Relaxin

It is secreted by the placenta. It causes pelvic ligaments to relax or contract in preparation for parturition (giving birth).

Reproductive system of a cow

Functions of parts of the reproductive system of a cow

 Reproductive system of a bull

The reproductive performance of a bull should be good in order to obtain a high percentage of calves, when natural service is used for breeding. A good bull must be fertile and have high (libido) capable and willing to mate a large number of cows during a short breeding season for maximum production. An understanding of the bull's reproductive system will help the producer to understand breeding soundness examinations, reproductive problems and breeding impairments.

The reproductive system of a bull consists of the testicles, secondary sex organs, and three accessory sex glands. These organs work in concert for formation, maturation and transport of spermatozoa, which are eventually deposited in the female reproductive tract. The secondary sex organs are the epididymis, vas deferens and penis. The three accessory sex glands include the seminal vesicles, prostate and bulbourethral gland (Cowper's gland).

The male reproductive organs

Functions of the reproductive system of a bull

Animal nutrition

Maintenance and production rations

Ration is the measure of food given to an animal per day. The nutrients that are required by different types of livestock for growth and development are divided into groups as follows: carbohydrates, proteins, vitamins,minerals, fats and oils

Carbohydrates

They are important because they provide animal with energy for warmth, movement, growth and production.

Proteins

They are important for-body building, repair of broken tissues and reproduction.

Fats and oils

These produce energy like carbohydrates. The fat can be stored in the body of an animal around the heart, under the skin and around the stomach.

Minerals

Minerals are required by farm animals in order to keep healthy. The major minerals needed by animals are calcium and phosphorous. These are important for bone and teeth formation.

 Vitamins

They are important for the normal functioning of the body. Shortage of vitamins causes certain diseases and deformities for example shortage of vitamin(A) can results in night blindness, rough-skinned and paralysis in some cases.

Feeding rations

There are so many factors to consider in order to come up with a feeding program for a given animal. Such factors includes the type of animal sex, age body mass and purpose for which the animal is kept for. There are two types of feeds for animals which are maintenance and production rations.

Maintenance ration

This refers to the amount of feed required to keep an animal alive without gaining or losing weight. A maintenance ration usually provides the animal with daily life activities such as;

• Movement
• Digestion
• Warmth

An animal is in a state of maintenance when its body composition remains constant, when it does not give rise to any product such as milk from a cow, eggs from layers and meat from broilers etc. Maintenance rations are also very critical during periods of food scarcity when the farmers want to keep animals in good shape especially during winter seasons when the grass has lost much of protein levels.

Production ration

This is the food required by animal in addition to maintenance ration. Its uses is to supply

nutrients needed for production. For example cows  should produce more milk, layers should produce many eggs and broilers should produce more meat.     In whatever production is required, the producing animal need to be compensated for producing the product by being given production ration. This is calculated by increasing a percentage of the maintenance ration to it. There are certain classes of livestock that are only fed with production ration broilers for meat production. Broilers cannot be fed with maintenance rations as this meat quality and quantity. However other animals like beef cattle can be given maintenance ration when the animal have no production, for example old cows.

Factors to consider when calculating production rations

The quantity of a ration to be given to an animal is calculated basing on the following:

• Age of animal
• Activity of the animal
• Type of an animal
• Quality of feed

Calculating production ration using the Pearson Square method

The Pearson square method is used to calculate the mixing ratios of feed components to come up with a feed formulation of desired nutrient percentage concentration for a given animal.

Worked example

You are required to prepare a feed formulation of 22% digestible protein (DP) using soya bean cake of 32% protein concentration and crushed maize with 8% digestible protein (DP).

Procedure

1. Draw the pearson's square and make diagonal lines that touch opposite angles of the square.

1. Write 22% digestible protein (DP) at the center of the square as it is the desired digestible protein concentration.
2. Write the soya bean protein concentration percentage at the top left hand corner of the square 32% in this case.
3. Write the crushed maize concentration percentage (8%) at the bottom left hand corner.
4. Subtract the desired protein concentration percentage (22%) from the soya bean protein concentration (32%) to come up with the soya bean ratio and write it on the opposite diagonal corner.
5. Subtract 8% crushed maize DP from 22% desired protein content and place the answer on the opposite diagonal corner

Here is what we have discussed in this topic

•  Ovaries is are the organs in which eggs are formed in animals. The eggs (ova) are produced at the rate of one per month starting from puberty.
• After fertilization, the cervix is closed by mucous plug that prevent foreign bodies from entering the pregnant uterus.
• Farm animals are fed under maintenance or production ration.
• Maintenance  ration  provide  animals  for  daily  activities  such  as  digestion, movement, respiration and warmth.
• An animal feed under maintenance has a constant body composition.
• Production ration supplies nutrients needs for production for example if it is a cow it should produce milk.
• Broilers are some of the livestock that are only fed with production ration.
• Acow has a gestation period of 270 days.
• Ruminant animals reproduce by sexual means.
• The zygote grows and develops into a foetus in the uterus.
• Sperms are produced in the seminiferous tubules of the testis.
• The  Pearson's  square  method  is  used  to  determine  mixing  ratios  of  feed components.
• The quantity of a ration to be given to an animal is determined by type of animal activity of the animal and nutritional value of the feed.
• Aration is quantity of food given to an animal on daily basis.
• Types  of  rations  given  to  an  animal  are  classified  into  maintenance  and production ration.

Definitions

• Balanced diet - It is a diet which contains all the necessary food nutrients in the right proportions. The food contains proteins, carbohydrates, vitamins, minerals and fats in the correct quantities for a particular type of animal.
• Crude protein (CP) - This is a measure of protein content of a feed.
• Digestible crude protein (D.C.P) - This is the protein which can be broken down to simpler substances.
• Ration - This is a combination or a mixture of feeds fed to livestock to meet their nutrient requirements. It contains the necessary different classes of food such as vitamins, fats, carbohydrates, proteins and minerals.