DIFFERENCES BETWEEN MONOGASTRIC AND RUMINANT ANIMAL DIGESTIVE SYSTEM



DIFFERENCES BETWEEN MONOGASTRIC AND RUMINANT ANIMAL DIGESTIVE SYSTEM

MONOGASTRIC ANIMAL RUMINANT ANIMALS
Possesses only one stomach 1. Possesses four stomach compartments
It cannot ruminate or chew the cud 2. It can ruminate and chew the cud
It cannot digest cellulose and fibres properly 3. It can digest cellulose and fibres very well
Digestion is not aided by bacteria 4. Digestion is aided by bacteria
Its diet is mainly basal and concentrate feeds 5. Its dict is mainly grasses and other cellulose e.g. legumes
It cannot synthesize its own proteins unless supplied in the feed
6It can synthesize its own protein through microbial activities on the rumen
It does not regurgitate 7. It regurgitates
It has no rumen
It has rumen
Poultry, rabbits and pigs are examples
Cattle, sheep and goats are examples.







you can take a look at this quotation about ruminant and non-ruminenant animals
Non-ruminants have the highest relative use of dietary energy when the diet contains “low amount of NDF” (i.e., more or less 10-15% fiber). These diets will tend to be higher in fat and/or readily degradable carbohydrate such as starch which are highly digestible. Non-ruminants do not have the ability to handle large amounts of fiber in their diets and thus the energy obtained from the diet will decrease sharply as diet fiber (NDF) increases above 20%. Actually high fiber diets have been recommended as a way to control obesity in humans.

In contrast, ruminants have the highest relative use of dietary energy when the diet contains “high amount of NDF”. The “plateau” is however quite wide and range from 20 to about 55% before dropping sharply at “very higher” fiber diets. Ruminant have a greater fiber requirement than non-ruminant animals. At “very high” fiber levels, the ability to extract energy from the fiber is out-weighted by intake limitation (set amount of fiber can be consumed per day) and the work involved in the processing of the fiber (chewing activity to reduce particle size). At low NDF diet, ruminants are less efficient than non-ruminants because the loss of energy (in the form of methane) associated with the formation of volatile fatty acids in the rumen (in comparison to absorbing glucose as an end-product of carbohydrate degradation as in non-ruminants).
please scroll down for more on mono-gastric animals

HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. ENVIRONMENTAL FACTORS AFFECTING AGRICULTURAL PRODUCTION
2. DISEASES
3. 52. SOIL MICRO-ORGANISMS








78. APHIDS
79. WHITE FLY SEED BUGS
80. CASSAVA CULTIVATION
81. CASSAVA MEALYBUGS
82. VARIEGATED GRASSHOPPER
83. GREEN SPIDER MITE
84. COTTON STAINER








154. PROTOZOAN DISEASES
155. TRYPONOSOMIASIS
156. COCCIDIOSIS
157. RED WATER FEVER(PIROPLASMOSIS)
158. ENDO PARASITES
159. TAPE WORM
160. ROUND WORM OF PIGS
161. LIVER FLUKE
162. ECTO PARASITES
163. TICK
164. LICE


What digestive adaptations do ruminants have that make them different from monogastric (non-ruminant) animals in the way that they extract and use energy from their feed?

Some of the digestive adaptations include: a) cud chewing (i.e., rumination); b) pre-gastric fermentation of the feed in the rumen (in addition to gastric digestion; c) large amount of saliva high in bicarbonate and phosphate buffers that neutralized acids produced in the rumen in order to provide a hospitable envionment for microbial growth in the rumen; and d) A liver that has adapted to converting VFAs into nutrient that can be used by the body tissue of the host. For example, propionic acid is converted to glucose in the liver by neoglucogenesis, which can be taken up by the mammary gland to synthesize lactose (milk sugar) while acetic and butyric acids serve as building block of fatty acids that can be stored in body fat).

TYPES OF INCUBATOR AND THEIR USES


WHAT ARE INCUBATORS

Incubators are made in varying sizes and designs. It uses different types of fuel (e.g. oil lamp, electricity, etc) to supply the heat required.

Function of an incubator:

Incubators are machines used for hatching fertilised eggs artificially. It takes 21 days for fertilized eggs of domestic fowl to develop and hatch in incubators.


Types of incubators

include natural draught portable type and forced draught or cabinet type.

Conditions for Incubator to function:

Before fertilised eggs are placed, the incubator should be run for 12-24 hours. For incubators to function properly, they require the following conditions:
(1) Temperature range of 37oC – 39oC
(2) Relative humidity of 50 - 70%; at optimum level being 60%
(3) Adequate ventilation.








COMPONENTS OF AN INCUBATOR

An incubator is made up of a setter and a hatcher. The fertilized eggs are kept in the setter for 18days while for the remaining three days before hatching, the eggs are placed in the hatcher.
The components of an incubator are:
(i) heat source e.g. lantern, heater or electric heater
(ii) control unit, damper or thermostat; it regulates the temperature of the incubator
(iii) heat distribution unit;
(iv) relative humidity mediation unit which can be a basin of water, cotton-wool or humidifiers
(v) felt tray – (to hold eggs and reduce cracking) or egg racks or egg trays;
(vi) thermometer – to detect the degree of hotness or coldness of the machine
(vii) fan or air circulation unit or vent for ventilation
(viii) egg turning device for regular turning of eggs
(ix) insulator, to prevent heat loss


Problems Associated with the Functioning of the Components.

The problems that may lead to malfunction or non-functioning of t components of incubators include:
(i) If it is electrical incubator, power failure and irregular power sup would arise, but if it is kerosene heat incubator, the problem that will arise include running out of kerosene.
(ii) Thermostat: High or low voltage or current.
(iii) Fan: Irregular power supply; over-heating through over-usage; loose nuts of the parts; improper lubrication of the movable parts.
(iv) Thermometer: Problems include: cracking or breakage of the bulb/thermometer; loss of sensitivity.
(v) Ventilation: Blockage of vents.
(vi) Water basin: Leakages; drying up of water contents.
(vii) I n s u I a t o r Malfunctioning of the insulator unit.
(viii) Turning device for egg tray Lubrication of the movable joints or parts; loose nuts.


EFFORTS TO ENSURE UNIFORMITY OF HATCHING OF EGGS IN INCUBATOR

The steps that should be taken to ensure that eggs hatch at about the same time include:
(i) setting eggs uniformly in the tray
(ii) timely and regular turning of eggs;
(iii) ensure suitable environmental condition such as ventilation and relative humidity
(iv) proper handling of the eggs
(v) setting eggs at the same time
(vi) select eggs of the same sizes
(vii) Holding period for eggs before setting should not be more than 14days.








Operations Needed after the Hatching of Eggs in the Hatchery

Activities or operations normally carried out after hatching of eggs in the hatchery include:
(i) sexing of chicks;
(ii) drying of chicks;
(iii) intra-ocular (I) NDV vaccination;
(iv) sorting out abnormal chicks;
(v) Packing normal chicks.

HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
3. SUBSISTENCE AGRICULTURE
4. COMMERCIAL AGRICULTURE
5. PROBLEM OF AGRICULTURAL DEVELOPMENT
6. SOLUTIONS TO POOR AGRICULTURAL DEVELOPMENT
7. AGRICULTURAL LAWS AND REFORMS
8. ROLES OF GOVERNMENT IN AGRICULTURAL DEVELOPMENT
9. AGRICULTURAL POLICIES
10. PROGRAM PLANNING IN AGRICULTURE
34.
FORESTRY
35. WILDLIFE CONSERVATION
37. TOPOGRAPHY
38. SOIL
39. BIOLOGICAL FACTORS
42. CLIMATIC FACTORS AFFECTING AGRICULTURAL PRODUCTION
43. TEMPERATURE
44. RAINFALL
45. WIND
46. SUNLIGHT
47. SOLAR RADIATION
48. BIOTIC FACTOR AND AGRICULTURAL PRODUCTION
49. PESTS
50. BIRDS
51. DISEASES
52. SOIL MICRO-ORGANISMS
53. SOIL PH
54. ROCK FORMATION
55. IGNEOUS ROCK
56. SEDIMENTARY ROCKS
57. METAMORPHIC
58. SOIL AND ITS FORMATION
59. FACTORS OF SOIL FORMATION
60. LIVING ORGANISM
61. PARENT MATERIALS
62. SOIL FORMATION TOPOGRAPHY
63. PROCESS OF SOIL FORMATION
64. WEATHERING
65. PHYSICAL WEATHERING
66. CHEMICAL WEATHERING
67. PRESSURE
68. WATER
73. BIOLOGICAL WEATHERING
75. SOIL WATER
80. SANDY SOIL CLAY SOIL LOAMY SOIL
83. SOIL TEXTURE
85. RETENTION OF WATER BY VARIOUS SOIL TYPES
soil improvement techniques
90. MACRO NUTRIENTS IN GENERAL
112. THE MAINTENANCE OF SOIL FERTILITY
113. CROP ROTATION
118. FARMING PRACTICES
119. BUSH BURNING CLEARING
121. FERTILIZER APPLICATION
122. ORGANIC MANURING FARM YARD MANURE
126. CROP ROTATION
133. FARM POWER AND MACHINERY
134. SOURCES OF FARM POWER
135. HUMAN SOURCE
149. PLOUGHS
142. FIELD MACHINES
157. PLANTERS
164. SIMPLE FARM TOOLS
165. AGRICULTURAL MECHANIZATION
166. THE CONCEPT OF MECHANIZATION











INCUBATION PERIOD OF BIRDS


INCUBATION OF EGGS

Definition: Incubation is the process providing fertilized eggs with optimum conditions of temperature, relative humidity and ventilation necessary for development of chicks and their success itching.







TYPES OF INCUBATION

There are two types of incubation. These are:
1.

Natural Incubation:

The natural incubation is done by the hen itself, after having a number of eggs. The hen broody i.e., it stops laying in order incubate the eggs already laid. The hen lays up to 15 eggs and stops. It sits on the e 4 provides all conditions of temperature relative humidity and ventilation required for the chicks to develop and hatch. It turns its eggs on regular basis. This practice is common in the villages where chickens are raised extensively and places where there are no facilities for artificial incubation.
Natural incubation is not desirable in commercial poultry production because, when hens go broody, egg production stops i.e. the commercial enterprise will not realize a good number of eggs from its flock.
The number of eggs that can be incubated by a hen at any time is very small.
Storage: The body temperature of hen is between 41’C- 42C. At the time the egg is
2.

Artificial Incubation:

This is designed to provide the ideal conditions naturally provided by hen. It uses manmade devices called incubators to provide optimum conditions necessary for the development of the embryo into chick. The incubator is the most important equipment in hatchery. Many types of incubator, ranging in size from small to room type, are made. Eggs are set in trolleys.







ADVANTAGES OF ARTIFICIAL INCUBATION

1. Hens do not have to stop egg production. Consequently, a large number of eggs are produced within a short period.
2. Large number of eggs are incubated and hatched at the same time (incubators of over 100,000 egg capacity are even available)

Collection and Storage of Hatching Eggs

Collection: Hatching eggs are supposed to be collected at least 3- 4 times a day. Under our tropical environment, it is good to collect more often than this. This will help to reduce deterioration and consequently reduce hatching potentials.

Storage: The body temperature of hen is between 41oc – 42oC. At the time the egg is dropped, it is at that body temperature and the embryonic development still continues. This reduces the hatching potential of the egg. Consequently, eggs are stored in egg holding room for periods ranging from two days to two weeks.
Storage conditions include a temperature of about 1 8 and a relative humidity of 75 -80 %. Eggs are stored with the large end facing upward while turning of the eggs may not be necessary within the first two weeks but above two weeks. Turning is advisable to prevent contact of embryos with shell membrane, which may cause dehydration or physical damage.


MEASURES FOR THE EFFICIENT OPERATION OF AN EGG INCUBATOR

(i) Maintain the right temperature during incubation
(ii) Test-run the incubator before you set eggs inside
(iii) Maintain the right RH during incubation
(iv) Allow for adequate escape of CO, from incubator
(v) Ensure a regular power supply to the incubator
(vi) Place incubator away from walls
(vii) Candle eggs progressively
(viii) Fumigate incubator before setting eggs
(ix) Incubator should be handled by trained and experience personnel

Incubation Procedures

(1) Prior to setting eggs in the incubators the eggs should be brought out from cold room and left to attain random temperature in order to eliminate sweating.
(ii) The incubator which must have been cleaned and disinfected if started early enough, to attain optimum temperature and relative humidity before eggs are placed in it.
(iii) The eggs are arranged in egg setting trays and placed in the incubator. It is good practice to fumigate the eggs before setting.







Optimum Incubation Conditions

(i) Temperature: Temperature is usually37-39°C.
(ii) Relative humidity: Relative humidity of 50 - 60% during the first 19 days and 75% during the last two to three days to prevent dehydrating the chicks in the hatcher.
(iii) Ventilation (Air flow): Free movement of oxygen, nitrogen, carbon dioxide and water vapour through the shell is very essential for the developing embryo. The tolerant limit of carbon dioxide in incubator or hatcher is 0.5%.
(iv) Egg Positioning during Incubation: Eggs are usually placed in the incubator with the large end facing upward. However, some studies indicate that eggs set with the large ends downward hatch equally good and under natural conditions, the hens hatch eggs in horizontal position.
(v) Egg Turning: If eggs are left in one position throughout the incubation period, they hatch poorly. This is because of physical damage caused b.the yolk sticking to one side of the shell. Under natural conditions, .the hen turns the eggs with her beak and body. However, modern incubators are also equipped with automatic turning mechanism which turns the eggs six to eight times a day.

Hatching:

The 21-day incubation period of domestic fowl can be seen as consisting of first 18-19 days incubation in the setter and last two to three days hatching in t
Hatching Operation
(i) Testing for fertility: Infertile eg and dead embryo can be detected about days after incubation by the process call candling. The machine used to detect living or dead and developing embryos called the egg candler. Candling consists of the passage of concentrated source of light through the egg in a dark room in order to see through the egg. It is usually not done in commercial basis because of the number of eggs involved. However, it is routinely done in research stations. At least two candling are done usually in six to seven days of incubation. With candling, you can determine fertile eggs. Here, live embryo shows a spider-like appearance in the egg. Infertile eggs are clear with no spider-like appearance.
During first candling, one can determine embryos that die during the first week called Dl (died within first week). These eggs do not show any radiating blood vessels. Rather, blood vessels adhering to the shell or a pink blood ring maybe seen.
Second candling is done in e 18/19 day prior to transfer of, the eggs from setter to the hatcher for hatching. If the first candling was well done, only dead embryos in the period between he first and second period will be tested put ,tie 1ie embryo nar1y fills the egg or moves when tie egg is rotated and blood vessels become apparent. Dead embryos appear as a liveless mass of dark shadow. During the second candling, the live embryo fills the entire egg, i.e., D.

EFFORTS TO ENSURE UNIFORMITY OF HATCHING

The steps that should be taken to ensure that the eggs hatch at about the same time include the following:
(i) setting eggs uniformly on the tray
(ii) timely and regular turning of eggs
(iii) ensure suitable environmental conditions, i.e temperature, relative humidity and ventilation
(iv) proper candling of the eggs
(v) setting eggs at the same time
(vi) selecting eggs of the same size
(vii) holding period for egg before setting should not be more than 14 days (2weeks)







OPERATIONS REQUIRED AFTER HATCHING

Activities or operations normally carried out after hatching of eggs in the hatchery include:
(i) sexing of chicks into male and female
(ii) drying of chicks
(iii) intra-ocular (I) NDV vaccinations
(iv) sorting out abnormal chicks
(v) packing of normal and healthy chicks


HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
3. SUBSISTENCE AGRICULTURE
4. COMMERCIAL AGRICULTURE
5. PROBLEM OF AGRICULTURAL DEVELOPMENT
6. SOLUTIONS TO POOR AGRICULTURAL DEVELOPMENT
7. AGRICULTURAL LAWS AND REFORMS
8. ROLES OF GOVERNMENT IN AGRICULTURAL DEVELOPMENT
9. AGRICULTURAL POLICIES
10. PROGRAM PLANNING IN AGRICULTURE
34.
FORESTRY
35. WILDLIFE CONSERVATION
37. TOPOGRAPHY
38. SOIL
39. BIOLOGICAL FACTORS
42. CLIMATIC FACTORS AFFECTING AGRICULTURAL PRODUCTION
43. TEMPERATURE
44. RAINFALL
45. WIND
46. SUNLIGHT
47. SOLAR RADIATION
48. BIOTIC FACTOR AND AGRICULTURAL PRODUCTION
49. PESTS
50. BIRDS
51. DISEASES
52. SOIL MICRO-ORGANISMS
53. SOIL PH
54. ROCK FORMATION
55. IGNEOUS ROCK
56. SEDIMENTARY ROCKS
57. METAMORPHIC
58. SOIL AND ITS FORMATION
59. FACTORS OF SOIL FORMATION
60. LIVING ORGANISM
61. PARENT MATERIALS
62. SOIL FORMATION TOPOGRAPHY
63. PROCESS OF SOIL FORMATION
64. WEATHERING
65. PHYSICAL WEATHERING
66. CHEMICAL WEATHERING
67. PRESSURE
68. WATER
73. BIOLOGICAL WEATHERING
75. SOIL WATER
80. SANDY SOIL CLAY SOIL LOAMY SOIL
83. SOIL TEXTURE
85. RETENTION OF WATER BY VARIOUS SOIL TYPES
soil improvement techniques
90. MACRO NUTRIENTS IN GENERAL
112. THE MAINTENANCE OF SOIL FERTILITY
113. CROP ROTATION
118. FARMING PRACTICES
119. BUSH BURNING CLEARING
121. FERTILIZER APPLICATION
122. ORGANIC MANURING FARM YARD MANURE
126. CROP ROTATION
133. FARM POWER AND MACHINERY
134. SOURCES OF FARM POWER
135. HUMAN SOURCE
149. PLOUGHS
142. FIELD MACHINES
157. PLANTERS
164. SIMPLE FARM TOOLS
165. AGRICULTURAL MECHANIZATION
166. THE CONCEPT OF MECHANIZATION




REPRODUCTIVE ORGANS, MATING AND IN FARM ANIMALS



MATING

Reproduction is the process by which off-springs are produced. All farm animals multiply by means of sexual reproduction.
It begins with fertilization which is the fusion of male and female gametes to form a zygote. Fertilization takes place internally in the body of the female. The embryo(zygote) formed develops inside body of mother, fed and protected until end of gestation period.
In poultry, the process is different in that eggs are fertilized internally but laid and development of the chick takes place outside during incubation
(i) Mating is also called coitus or corpulation
(ii) Mating is the act in which the private part of the male is inserted into the private part of the female, leading to depositing of spermatozoa
(iii) Mating in farm animal may lead to fertilization
(iv) It is under the influence of hormone
(v) Mating is necessary before farm animals can reproduce sexually
(vi) For mating to occur, the female animal must be on heat period
(vii) The male organ must be erect before mating can occur
(viii) It takes place when the male mounts the female for sexual corpulation
(ix) It leads to the occurrence of depositing of seminal fluid containing spermatozoa which is deposited in the female opening


TYPES OF MATING

(a) Natural mating: This occurs when a male, after identifying a female on heat period will mount on the female for mating the animal. Examples of natural mating are
(i) Flock mating: both male and female animals are allowed to move together and mate freely
(ii) Pen Mating: Very few number of males are kept together with limited number of females so that they can mate any time the female animals is on heat period, e.g four males together with twelve females
(iii) Stud or Hand mating: The males are kept separately to be mated with individual females when on heat period. After mating, the male is taken away artificial mating: This is called artificial insemination which involves the act of injecting spermatozoa artificially into the female animal on heat period. The reproductive cells are collected from a male animal with desirable characters,. Such spermatozoa are stored at 196oC under liquid nitrogen until it is used


ADVANTAGES OF ARTIFICIAL INSEMINATION

(i) It is cheaper to import sperms than to import the male animal
(ii) Sperms 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 managing male animals
(iv) Sperms can be used over a long time even after the death of the male animal







The breeding of animals is under human control, and the breeders decide which individuals shall produce the next generation. The breeder makes a choice.

The breeding of animals is based upon the fact that certain qualities are genetic ,hence valuable qualities are passed on from parents to off -springs. The qualities can be maintained or improved in the next generation.
you can read crop improvement process here
The performance of an animal is influenced by two major factors;

Genetic potential

The environment, which includes:
Feeding,Health, care and the ecological conditions.

The genetic potential of an animal is inherited from its parents.

In selection and breeding animals with superior characteristics are selected and allowed to mate.

In the process they transmit the superior characteristics to their offspring.

When this is done over a long period of time, it results in livestock improvement.

Reproduction and Reproductive Systems


Reproduction is the process by which off-springs are produced. All farm animals multiply by means of sexual reproduction.

It begins with fertilization which is the fusion of male and female gametes to form a zygote. Fertilization takes place internally in the body of the female. The embryo(zygote) formed develops inside body of mother, fed and protected until end of gestation period.
In poultry, the process is different in that eggs are fertilized internally but laid and development of the chick takes place outside during incubation.

In both male and female, certain organs are specialized for the process of reproduction.

Some of these organs secret fluids which are necessary for the movement and survival of the gametes(reproductive cells.)







Reproduction in Cattle

1.

Male Reproductive System (Bull)

The male reproductive organs produce the male gametes,the spermatozoans.
These are introduced into female reproductive system, where they fuse with the sperm to form zygote.
The reproductive system(bull) is composed of the following parts;
i). Testes
ii). Epididymis
iii). Sperm ducts
iv). Accessory glands(Seminal vesicles and prostrate glands)


Bull.jpg

The testis:

There are two testes hanging loosely between hind legs.

Enclosed by loose skin (scrotum)scrotum regulate temperature of testis for optimum production of sperms.

Produce spermatozoa(sperms)which are stored in coiled tube called epididymis.


Epididymis: Storage of spermatozoa.

Sperm ducts:

Conveys sperm from the testis and urine through the male organ

sphincter muscles contract to allow each to pass separately.

Seminal vesicles produce fluid called seminal. Seminal carries sperms out of male organ in fluid form.
Seminal fluid contains nutrients to the spermatozoa.

Prostate gland -produce fluid that neutralize the acidic effects of urine in the urethra preventing death of sperms.

Accessory glands: Include seminal vesicles cowpers gland and prostate gland. Urethra: Conveys urine and spermatozoa. One sperm fertlizes ovum

the male organ


Surrounded by a sheath which is an extension of skin.

It introduces sperms into the female opening of a cow .

It is a copulatory organ, also used for urination.


2. The Female Reproductive System(Cow)

the reproductive system of a cow is composed of;
i). Ovaries
ii). Fallopian tubes
iv).
v). Uterus

Ovaries and fallopian tubes(oviduct)

Two ovaries located in abdomen, left and right. Produce ova/eggs and hormones which control sexual cycle. Oestrogen produced by graafian follicle inside ovary induces oestrus i.e. Heat period so that the cow shows signs of heat. The hormone oestrogen is produced under the influence of other hormone called the Follicle stimulating hormone.

After every 21 days the ovary releases a mature ovum and the cow comes on heat. The ovum travels through the fallopian tubes to the uterus.

The release and movement of the ovum down to the uterus is called ovulation. If mating is done at this time, fertilization will take place.
The fertilized egg implants itself onto the endometrium(walls of uterus)and develops into foetus.

Fallopian tubes:

Fertilization takes place here. Also a passage for the egg from the ovary to the uterus.

The uterus:

Implantation takes place here and also embryo develops here.

The cervix of the uterus: Closes the uterus.

The outer opening

The outer opening is the external opening of female reproductive system.

It allows mating to take place so that sperms are deposited

The foetus and urine are removed through the The outer opening.

Pregnancy period for most farm animalsis period between fertilization of ova and the expulsion of the foetus through the The outer opening. Also called gestation period. In cattle gestation period is 270-285 days. Ends with the birth of a calf.
The reproductive tract undergoes a period of rest during which it is repaired and returns to normal. During pregnancy, hormone called progesterone is produced by the placenta to maintain the foetus in the uterus.
Animal Length of days
Cow 270-285 Days
Sow 113-117
Ewe/Goat 150
Rabbit 28-32

Parturition

Act of giving birth called parturition. This time the foetus expelled through the birth canal.

When an animal is about to give birth, it shows signs;-

Distended udder which produces thick milky fluid called colostrums.
Swollen outer opening producing thick mucus like discharge.
Loose and slackened pelvic girdle.
Visible pin bones.
General restlessness.

Animal parturates within 2-3 hours after this signs. The correct presentation is with the front feet first ,and the head outstretched and resting in between the feet.
Any other presentation called mal-presentation or breech presentation and requires assistance.





Reproduction in Poultry


The male chicken has no special male organ but a small opening near the vent through which sperms are emitted. male chicken has testes within the body.

The hen has elongated oviduct for formation of an egg. Fertilization occurs internally.

During mating the cloaca of the hen and the vent of the male chicken fit into each other and then seminal fluid is poured into the cloaca ,then sucked to the oviducts.

The Reproductive System of a Hen
The reproductive system has the following parts;
i). Ovary
ii). Funnel(infundibulum).
iii). Magnum
iv). Ishtumus
V). Uterus/Shell gland
vii)
viii). Cloaca

Ovary

Hen has two ovaries but one functional. Ova is formed in ovaries.
About 3500-4000 ova present inside ovary held by follicle. Mature ovum released via rapture of follicle. It moves into oviduct received by the funnel.

Funnel(infundibulum)
Fertilization occurs here. Chalazae also added to yolk.
It also collects the ovum and stores the sperm. Time here is 15 minutes and it is 11.6cm long.

Magnum
Thick albumen is added and stays for 3hrs. its 33cm long.

Isthmus
Its 10.6cm long, Shell membranes added and determines shape of egg.
Water, mineral salts and vitamins added and takes 15 minutes.








Uterus(shell gland)
Calcium deposits i.e.shell added around the egg. Pigments added.
Addition of albumin finished and stays here for 18-22hours.


Cloaca
Egg moves out of cloaca through the vent and the cloaca extents out to prevent the egg from breaking.
NB;
Egg formation not depended on fertilization. Egg formation takes 24-26hours.
The components of egg are obtained from body reserves of the hens body.

Selection of Breeding Stock


Selection is used as a tool for livestock improvement. A breeding type is a group of males and females which act as parents of future generations.
Selection is the process of allowing certain animals to be parents of future generations while culling others.
Culling is the removal of animals which do not perform to the desired level, from the herd. The animals retained have certain desirable characteristics which make them produce more.

Selected animals make up the breeding stock.
The breeding stock should pass the good qualities to their offspring for better performance, to improve the livestock.
Selection process repeated for many generations increases chances of formation of desirable qualities in an animal.
Genetically termed as gene frequency(occurrence of the genes that carry desirable characteristics.) Selection increases occurrence of desirable genes and decreases occurance of undesirable genes.
During selection, the characteristics to be selected for are first studied closely to ascertain that it is not influenced by the environment, but mainly by the genetic make-up.
Selection helps improve characteristics which are highly heritable.
Heritability means the likelihood of a particular trait to be transmitted to the offspring and they are strongly inherited.
A character like milk yield is lowly heritable, i.e. it is weakly inherited and a bigger percentage of the character is affected by the environment.
The degree to which selection affects a character depends on the following factors;
The heritability of the character, The intensity with which the selection is done and the interval between generations and kind of selection being practiced.

Factors To Consider When Selecting A Breeding variety.

Age
Level of performance
Physical Fitness

Health
Body Conformation
Temperament or Behaviour
Quality of products
Mothering Ability
Adaptability
Prolificacy

Age

Young animals,
Those that have not parturated for more than 3-times, should be selected.
They have a longer productive life.
Old animals are poor breeders and low producers.
Production and breeding efficiency decline with age.

Level of performance

Animals with highest production level selected.
Performance best indicated by records.

Good performance of animal indicated by;

High milk, wool and egg production,
Good mothering ability
High prepotency which is the ability of a parent to pass good qualities to their offspring.
The animals with poor performance should be culled.
Good records kept and used by the farmer for this purpose.

Physical Fitness
Animals selected should be free from any physical defect e.g.

mono-eyed,
limping,
irregular number of teats,
scrotal hernia,
defective and weak backline







Health

Sick animals do not breed well and are expensive to keep.
Animals that are resistant to diseases pass these characteristics to their offspring
Body Conformation

Animals for breeding to be selected according to proper body conformation.
A dairy cow should be wedge-shaped with a large udder, thin legs, long neck.

Temperament or Behaviour

Animals with bad behaviors should be culled. e.g Cannibalism, egg eating, aggressiveness, kicking

Quality of products

Select animals that give products of high quality such as meat, wool, eggs, milk.

Mothering Ability

Animals selected should have a good mothering ability,
That is animals with good natural instinct towards their young ones.
This will enable them to rear the young ones up to weaning.

Adaptability
Animals selected should be well adapted to the prevailing climatic condition in the area e.g Arid and semi arid areas.

Prolificacy

Animals selected should be highly prolific.
That is, animals with the ability to give birth to many offspring at a time(larger litter).
This is a quality that should be considered when selecting pigs and rabbits.
The ancestry records assist to choose the prolific breeds for mating

SELECTION OF CATTLE AND SHEEP
Selection in cattle

Consider the following;

Level Of Performance Which Include;

Milk Yield Butter Content.

Length Of Lactation Period.

Calving Intervals.

Age of the Animal, Fertility, physical Fitness, Health Of The Animal, Body Conformation and suitability of the enterprise-milk or beef

Selection in sheep

Consider the following;

Level of performance which includes;

Mothering ability

Growth rate

Wool quality

Carcass quality

Twining rate Age

Suitability to the enterprise-wool or mutton
Flocking instinct Health of the animal
Physical fitness
Inheritable defects
Fertility
Inheritable defects.
Fertility.

Selection in Goats
Consider the following:
Fertility.
Mothering ability.
Growth rate.
Twining rate
Carcass quality/dressing percentage
Growth rate.
Suitability to the enterprise - milk or mutton.
Health of the animal.
Age.

Selection in Pigs

Consider the following:
Carcass quality/dressing percentage
Suitability to the enterprise (bacon or pork)
Growth rate.
Health of the animal.
Mothering ability.
Prolificacy.
Number of teats
Temperament.
Body formation.
Age.
Heredity defects

Selection in Camels
Health of the animal.
Age.
Temperament.
Foraging ability.
Fertility.
Level of performance-milk, meat, fur and transport.

METHODS OF SELECTION

These include:

Mass selection - Animals with superior characteristics (highly heritable breeds) are selected from a herd and then allowed to mate among each other at random. The offsprings will show higher performance than their parents. This is because mass selection increases the occurrence of the desirable genes in a population.
Progeny testing - is a offspring resulting from selected parents ( Family selection). In this method a group of progenies (offrpring) are used as an aid to increase accuracy in the selection of a breeding type. This is method is used when the character to be selected is of low heritability and expressed by one sex only.
This method takes up to nine years for the results to be seen

Contemporary comparison
Contemporaries refers to other heifers in the herd sired by the same bull.
This is a progey tasting method which involves comparison of average production of daughters (Heifers) of each bull with that of the other heifer reffered to as contemporaries.
In this methods it is assumed that the difference between the herds of the same breed are non-genetic in origin.

advantages

It is possible to compare heifers of different ages in different locations worldwide.
It eliminates difference brought about by the environment.
it is possible to make direct comparison of stut bulls at different artificial insemination centres.
It is accurate since we are using a large herd of animals.







Breeding

Process of mating selected males and females to produce offspring with the desired characteristics.

Reasons:

To expand the inherited potential of the animal.
To improve production by introducing new genes.
To overcome production problems created by the environment.
To satisfy consumers taste.
For economic reasons e.g fast growth rate to reach the market early.

Terms Used in Breeding

Inheritance; Genetic transmission of characteristics from parents to offspring.
The mechanism of inheritance is carried by the sex cells (gametes) and is controlled by genes found in the chromosomes.
Genes are very tiny units of inheritance carrying particular characteristics, such as colour, body shape and amount of milk production. Chromosomes are genetic materials which carry genes.
They exist in pairs paternal and maternal) in the nucleus of the body cells. They are always constant in number.
Dominant and Recessive Characteristics
A dominant gene is one that suppresses the other. It produces a dominant characteristic.

A recessive gene is one that is suppressed by the other. It produces a recessive characteristic.

Hybrid and Hybrid Vigor
A hybrid is an animal which is the product of crossing animals of two different breeds. It has both a dominant and recessive characters. A superior hybrid has 75% dominance and 25% recessive.

Hybrid vigour or heterosis is increased vigour and performance resulting from crossing two superior breeds. When two superior breeds e.g Pedigree friesian and Jersey breeds are mate the resultant offspring have both the character of high milk yield and high butterfat content. Thus it is said the offspring have hybrid figure which is an increased perfomance and figure than both the two parents.

Epistasis
This is the masking of the effect of one gene (recessive gene) by another gene(dominant) which is non-allelic, that is situated on different locus.
This is aimed at preventing the recessive gene from being expressed.

BREEDING SYSTEMS
They are categorized into two namely; Inbreeding and Out-breeding

1. Inbreeding
Mating of animals which are related i.e have certain alleles of genes in common.
Reasons:

To increase genetic uniformity in a herd.
To increase phenotypic uniformity.
To get proven sires.
To fix required characteristics when developing a new breed.
used in animal of higher prepotency (stud Bulls)

Limitations
It can bring about loss of hybrid vigour.
It may lead to decline in fertility.
It may lead to high rate of pre-natal mortality.

Systems of Inbreeding
Close Breeding: mating between very closely related animals, for example sib-mating and parents sib-mating.
Line Breeding: mating of distantly related animals that had a common ancestor for example cousins, halfbrothers/sisters, grand daughters and grand sires.

2. Outbreeding

Mating of animals which are not related.
Reasons:

To introduce new genes in an existing breeding herd.
To exploit heterosis resulting from a cross between two breeds.
To develop a new breed or a grade animal.

Limitations

Lack of uniformity in animals that result from out-breeding.
Desirable characteristics may be lost due to variation.

Systems of Outbreeding
i). Cross-breeding
Mating of animals from two different pure breeds to attain hybrid viguor or heterosis such as higher production rate, higher production rate, high growth, disease resistance and heat tolerance.

ii).Out-Crossing

Mating of unrelated animals from the same breed for example fresian cow in kenya with Seminal fluid of fresian bull from Britain.
iii) Upgrading/Grading up/Back-crossing
Mating where the female of a cow grade (locals) is mated with a pure breed sire. The resultant animal is referred to as a high grade.
If the same sire mates with filial generation (F1-6) of its heifers, it will attain a pure breed character. With Artificial insemination (A.I) the systemis used widely to improve the local cattle for better milk production

Mating in Livestock

Mating in Cattle

Heat signs occur every 21 days.

The heat period last for 18-30 hours on average 24 hours.

Cow should be served 12-18 hours after showing the first heat signs.

Heat Signs

Restlessness.

Mounting on others and when mounted on she stands still. Rise in body temperature.

Drop in milk production in lactating cows. the female private part swells and becomes reddish.

Clear or slimy mucus from the opening

Bellowing or mooing frequently.

Mating in Pigs

Heat signs in pigs occur after every 21 days. The heat lasts about 72 hours.

Sows or gilts should be served in 18- 36 hours of the heat period.

Signs of Heat

Restlessness.

Frequent urination.

Swelling and reddening of the
Clear or slimy discharge from the

Frequent mounting on others.

It responds very well to the 'riding test'.

Mating in Rabbits

Does are ready for mating 6-7 months of age. Heat signs occur every 14 days.

The doe should be taken to the buck and not vice versa.

Signs of Heat

Restlessness.

Frequent urination.

.

The doe throws herself on the side.

The doe rubs herself against the wall or any other solid object.

The doe tries to contact other rabbits in the next hutch by peeping.

Methods of Service in Livestock

Natural Mating

Advantages:

It is more accurate.

It is less laborious.

Useful when heat signs of females cannot be easily detected.

Disadvantages

Inbreeding is not easily controlled.

Transmission of breeding diseases.

Extra feed for the male is required.

Large males can injure small females.

Wastage of semen.

It is cumbersome and expensive to transport a bull to remote areas.

Artificial insemination

Introduction of semen into the female reproductive tract by artificial means.

Advantages

There is economical use of seminal fluid.

It controls transmission of breeding diseases.

Sires that are unable to serve cows due to heavy weight or injury can produce seminal fluid to serve cows.

It prevents large bulls from injuring small cows. It reduces the expenses of keeping a male animal.

A small scale farmer who cannot afford to buy a superior bull can have the cows served at a low cost.

Semen can be stored for long. It helps to control inbreeding.

It eliminates the threat of keeping dangerous bulls from the farm.

It makes research work easier.



Disadvantages

Harmful characteristics can be spread quickly by one bull to the offspring.

It requires skilled labour.

Low chance of conception due to death of seminal fluid during storage.

It is laborious:

Embryo Transplant

It is the implantation of an embryo (fertilized ova) from a high quality female (donor) in the uterus of a low grade female (recipient).

Advantages

Faster multiplication of an animal with superior characteristics . It is easier to transport embryos than the whole animal.

Embryos can be stored for a long period awaiting the availability by recipient females.

It stimulates milk production in a female (recipient) that was not ready to produce milk.

Low grade animals can be used in production and rearing of high quality animals. Offspring of a superior female can spread quickly in an area.

Disadvantages

It is expensive.

It requires skilled personnel.

It requires special equipment for fertilization and storage of embryos.

Signs of Parturition in Livestock

Parturition is the act of giving birth in female animals.

Parturition in Cattle

The gestation period in cattle is 270-285 days averaging 280days.

Signs of Parturition

Restlessness



Clear mucus discharge from the outer opening.

Slackening of the pelvic muscles.

Full and distended udder.

Thick milky fluid from the teats.

A water bag appears and bursts just before calving.

Parturition in Pigs

The gestation period in pigs is about 4 months or 3 months, 3 weeks and 3 days.

Signs of Parturition

Restlessness.

The vulva turns red and swells.

The udder becomes full with a milky fluid the sow starts to prepare a nest by collecting some beddings at one comer of the pen.

Parturition in Rabbits

The gestation period in rabbits is 28-32 days.

Signs of Parturition


Preparing a nest by plucking off hair from her belly.

Goes off feeding

Restlessness.

The udder distends.

HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
3. SUBSISTENCE AGRICULTURE
4. COMMERCIAL AGRICULTURE

NERVOUS SYSTEM OF FARM ANIMALS




the nervous system

The nervous system includes all the organs and tissues which enable animals to respond to changes in their environment. A change in the environment is called a response.
The nervous system of mammals is composed of two parts: the central nervous system and the peripheral nervous system.








Central Nervous System

This is made up of the brain and the spinal cord. Both are made up of thousands of nerve cells or neurones. The functions of the central nervous system is correlation of impulses from various sense organs and storage of impulses as information or impressions in the brain for reaction to future similar stimuli.

(a)

The Brain:

the brain is enclosed in a bony case called the cranium. It is divided into fore, mid and bind brain
The fore brain consists of olfactory lobes which receive sensory impulses for smell and the cerebrum which is the seat of consciousness, intelligence, memory and all voluntary actions. The mid brain consists mainly of optic, lobes which control sight. The hind brain consists of the cerebellum which is concerned with balance and body posture, receives impulses and coordinates action, respiration, heartbeat, digestive movements and blood supply.

(b)

The Spinal Cord:

The spinal cord stems from the medulla oblongata and runs through the neural canal of the vertebral column or backbone. It communicates between the brain and other parts of the body. It controls all the reflex (involuntary) actions of the body.

The Peripheral Nervous System:

The peripheral nervous system consists of the cranial and spinal nerves and the autonomic nervous system. The cranial and spinal nerves of the peripheral nervous system together with the central nervous system mediate relations between the animals and its external environment. On the other hand, the autonomic nervous system, consisting of the sympathetic and parasympathetic nervous systems regulates events within the animal.

A neurone (nerve cell)

is the structural and functional unit of the nervous system. It helps in receiving and relaying of transmission of impulses.

A neurone has three main parts:
The dendrite, cell body and the axon (nerve fibre or axis cylinder).
The cell body has dendrites extending from it, and a central nucleus. The axon is surrounded by myelin sheath which is interrupted at intervals, forming nodes of ranvier. The axon terminates in dendrites.







TYPES OF NEURONES

(i) Sensory or Afferent Neurone: These neurones carry impulses from receptors, such as the eyes, skin, ears, etc. to the central nervous system.
(ii) Motor or Efferent neurone: These neurons carry impulses from the central nervous system, such as muscles and glands in the body
(iii) Intermediate or Relay neurons: These neurons receive, transmit and interpret messages in the spinal cord and brain


Transmission of Nerve Impulse
The dendrites usually receive messages and pass them to the cell body which then passes them (messages) out through the long axon to the dendrites of another nerve cell. However, there is no direct connection between the fibres of adjacent neurones. The junction between one end of a dendrite of one neurone and that of an axon of the next neurone is known as a synapse. The message passes from cell to cell across these synapses.


Reflex actions:

These are actions carried out by animals in response to certain stimuli without first thinking or planning for them. They are not under the control of the brain. They are quick, automatic responses and entirely stereotype in nature. Examples of simple reflex or involuntary actions include: (i) the blinking of the eyes (ii) the beating of the heart (iii) sneezing (iv) sudden removal of hands, legs or skin from hot object. (v) the jerking of the legs on tapping the knee cap.


Reflex Arc:

A reflex arc is the path traced out by the impulses concerned in a simple reflex action. It consists of three neuroties - an afferent, intermediate anal efferent neurones.
The message from the external stimuli is received by the sensory or receptor organs such as the skin in the case of sudden removal of leg from hot object. The stimulus is sent to the brain or spinal cord
through the sensory or efferent neurone. The intermediate or relay neurone in the brain and spinal cord receives, transmits and interpretes the message. The interpreted message is then sent through the motor or efferent neurone to the organ or effector such as the muscle, which then causes the appropriate response, leading to the sudden withdrawal of the leg from the hot object.

FUNCTIONS OF THE NERVOUS SYSTEM

(i) It coordinates body functions
(ii) It is responsible for bringing about locomotion or movement
(iii) It enables the body to respond to external stimuli

HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.



64. WEATHERING
65. PHYSICAL WEATHERING
66. CHEMICAL WEATHERING
67. PRESSURE
68. WATER
73. BIOLOGICAL WEATHERING
74. CHEMICAL AND BIOLOGICAL COMPOSITION OF THE SOIL
75. SOIL WATER

78. PROPERTIES OF SOIL






79. SOIL STRUCTURE
80. SANDY SOIL
81. CLAY SOIL
82. LOAMY SOIL


126. CROP ROTATION
133. FARM POWER AND MACHINERY
134. SOURCES OF FARM POWER
135. HUMAN SOURCE
149.
PLOUGHS
142.
FIELD MACHINES
157.
PLANTERS
164.
SIMPLE FARM TOOLS
165. AGRICULTURAL MECHANIZATION
166. THE CONCEPT OF MECHANIZATION


PROCESS OF EGG FORMATION IN BIRDS



PROCESS OF EGG FORMATION IN BIRDS

The process of egg formation is controlled by hormones. The egg is formed partly in the ovary and partly in the oviduct.
The egg is formed in the reproductive tract of a female chicken, called a hen. The reproductive tract is divided into two major parts: the ovary and the oviduct. The ovary is where the yolk is added. When the yolk reaches the right size, it is released from the ovary by a process called ovulation. The released yolk is then picked up by the infundibulum. It is here that fertilization must take place.The yolk then passes to the magnum, where the albumen is added. It then goes on to the isthmus for the addition of the shell membranes

Ovary:

The yolk is secreted by the ovary and enclosed in a follicle. The yolk increases in size by accumulating yolk materials carried from different parts of the body by blood stream. The germinal disc is attached to the top of the yolk. The follicle burst to release the yolk.






Infundibulum:

The yolk released by the ovary is taken up by the infundibulum, the internal terminam part of the oviduct. Fertilization of the egg occurs in this part of the oviduct, before the other components are added. However, complete formation of the egg is independent of whether the egg is fertilized or not. The egg spends 15minutes in the infudibulum before it moves to the magnum.

Magnum:

In the magnum, the egg stays for three hours and part of the albumen is secreted on the yolk. Chalaza is also formed in this region. The egg now moves to the isthmus.
Isthmus: The egg stays here for 75minutes and the two shell membranes are formed. The shape of the egg is also formed at this region after which it moves to the uterus.
Uterus: The egg stays here for 19 – 20 hours where the shell is formed from calcium carbonate secreted by glands of the uterus. Mineral solutions are also added to the egg after which it moves to the outer opening.

hen outer opening:

The egg stays here for a very short time before it is laid through the cloaca or vent. It takes almost 26hours for a complete egg to be formed and laid.








MEMBRANE:

Immediately after the outer shell are outer and inner membranes. Both membranes give protection to the egg.

Airspace:

The airspace is located on one of the pointed ends of the egg. It is found in-between the outer and inner membranes. The airspace is very important for respiration of the embryo.

Albumen:

This is also called the egg white. It accounts for over 50% of the total body weight of the egg. It is rich on protein
Yolk: This is located at then centre of the egg. It is a yellowish jelly like mass. It is rich in proteins, mineral salts, vitamins and other food substances. It supplies the embryo nutrients.


Embryo:

This is also called germinal disc. This is located at the centre of the yolk as a dark spot. The germinal disc is only found in fertile eggs. It develops to form the chick during incubation period.
Chalaza: The chalaza extends to both sides of the yolk. It is a piece of thick protoplasm. It holds the yolk and the embryo in place within the albumen.

How a Hen Makes an Egg

The egg is formed in the reproductive tract of a female chicken, called a hen. The reproductive tract is divided into two major parts: the ovary and the oviduct. The ovary is where the yolk is added. When the yolk reaches the right size, it is released from the ovary by a process called ovulation. The released yolk is then picked up by the infundibulum. It is here that fertilization must take place.The yolk then passes to the magnum, where the albumen is added. It then goes on to the isthmus for the addition of the shell membranes. The developing egg spends most of its time in the shell gland, where the shell and any shell pigments are added. As the egg is being assembled it travels down the oviduct small end first. In the outer opening, it is pushed out, the large end first. This prevents the egg from being contaminated by fecal material when it is laid.

Formation of the egg

Reproductive organs of the hen

Reproductive organs of the hen

The egg is formed gradually over a period of about 25 hours. Many organs and systems help to convert raw materials from the food eaten by the hen into the various substances that become part of the egg.
The ovary

The hen, unlike most animals, has only one functional ovary - the left one - situated in the body cavity near the backbone. At the time of hatching, the female chick has up to 4000 tiny ova (reproductive cells), from some of which full-sized yolks may develop when the hen matures. Each yolk (ovum) is enclosed in a thin-walled sac, or follicle, attached to the ovary. This sac is richly supplied with blood.
The oviduct







The mature yolk is released when the sac ruptures, and is received by the funnel of the left oviduct (the right oviduct is not functional). The left oviduct is a coiled or folded tube about 80 cm in length. It is divided into five distinct sections, each with a specific function, as summarized in table 1.

Functions of various different sections of the hen's oviduct
the yolk
Section of oviduct Approximate time egg spends in this section Functions of section of oviduct
1 Funnel (infundibulum) 15 minutes Receives yolk from ovary. If live reproductive cell is present, fertilization occurs here (commercially produced table eggs are not fertilized)
2 Magnum 3 hours Albumen (white) is secreted and layered around
3 Isthmus 1 hour Inner and outer shell membranes are added, as are some water and mineral salts
4 Shell gland (uterus) 21 hours Initially some water is added, making the outer
white thinner. Then the shell material (mainly
calcium carbonate) is added. Pigments may also
be added to make the shell brown
5 cloaca, less than 1 minute The egg passes through this section before
laying. It has no other known function in the
egg’s formation

HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
3. SUBSISTENCE AGRICULTURE
4. COMMERCIAL AGRICULTURE
89. PLANT NUTRIENTS
90.
MACRO NUTRIENTS IN GENERAL
112.
THE MAINTENANCE OF SOIL FERTILITY
113. CROP ROTATION
MECHANIZATION
166. THE CONCEPT OF MECHANIZATION



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