Grade 12 Agricultural Sciences: Animal Nutrition, Feeds, Production, and Reproduction

Comprehensive vocabulary flashcards covering the Grade 12 Agricultural Sciences curriculum, including digestive physiology, animal nutrition, feed formulation, management systems, reproduction, biotechnology, and lactation.

Ingestion

The process whereby food is taken into the mouth.

Digestion

The process whereby food molecules are broken down into small particles through mechanical or chemical means.

Mechanical Digestion

The physical breakdown of large food molecules into smaller molecules, such as chewing, grinding, and churning.

Chemical Digestion

The breakdown of food by chemical reactions involving hydrochloric acid and digestive juices.

Absorption

The process whereby the digested food is taken up by the bloodstream.

Assimilation

The movement of digested food to different cells of the body.

Peristalsis

The involuntary contraction and relaxation of muscles that pushes food through the alimentary canal.

Retro-peristalsis

The involuntary contraction and relaxation of muscles that pushes food back to the mouth in the alimentary canal.

Pharynx

A funnel-shaped muscular tube connecting the mouth cavity to the digestive and respiratory systems.

Crop

An enlarged extension of the oesophagus in fowls where food is stored, moistened, and softened.

Proventriculus

The glandular stomach of a fowl that secretes digestive juices to chemically digest food.

Ventriculus (Gizzard)

The muscular stomach of a fowl that grinds food using swallowed small stones (mechanical digestion).

Forestomachs

The first three chambers of the ruminant stomach: the rumen, reticulum, and omasum.

Rumen

The largest compartment of the forestomach, lined with finger-like papillae and populated by microbes for fermentation of crude fibre.

Reticulum

The smallest compartment of the forestomach, characterized by a honeycomb pattern, which traps foreign objects like nails and wires (hardware stomach).

Omasum

The third compartment of the ruminant stomach with leaf-like folds that increase surface area for the absorption of moisture.

Abomasum

The true or glandular stomach of a ruminant that secretes hydrochloric acid and digestive enzymes, corresponding to the simple stomach of a pig.

Villi

Small finger-like projections on the mucosal surface of the small intestine that increase surface area for nutrient absorption.

Cloaca (Vent)

The common external opening for both the digestive and urinary systems in fowls.

Bile

A bitter, yellow-green, alkaline liquid rich in organic salts secreted by the liver and stored in the gall bladder to digest and emulsify fats.

Islets of Langerhans

The endocrine tissue of the pancreas that secretes the hormones insulin and glucagon directly into the bloodstream.

Rumination

The process in ruminants where food is chewed, swallowed, brought back to the mouth by regurgitation, and re-chewed (chewing the cud).

Eructation

The removal of accumulated fermentation gases (belching) through the mouth in ruminants.

Trocar and Cannula

A sharp, pointed medical instrument and sleeve used to puncture the rumen and treat severe acute bloating in cattle.

Oesophageal Groove

A muscular channel in young ruminants that directs milk directly into the abomasum, bypassing the undeveloped forestomachs.

Active Transport

The movement of nutrients against a concentration gradient (from lower to higher concentration) using energy supplied by ATP.

Passive Transport

The movement of nutrients along a concentration gradient from an area of higher concentration to an area of lower concentration without requiring energy.

Macro-elements

Inorganic mineral elements required by an animal in large quantities, such as calcium and phosphorus.

Trace-elements (Micro-elements)

Mineral elements required in very small quantities that are essential for good health and proper metabolic function.

Co-efficient of Digestibility

A measure of the digestibility of a feed expressed as a percentage of dry matter intake using the formula: $\text{Co-efficient Digestibility} = \frac{\text{Dry Matter Intake (kg)} - \text{Dry Manure (kg)}}{\text{Dry Matter Intake (kg)}} \times 100$.

Biological Value (BV)

A measure of the quality of protein in a feed, evaluated based on the proportion of essential amino acids it provides compared to ideal egg protein ($100\%$).

Complete Proteins

Proteins, typically of animal origin, that contain all essential and non-essential amino acids and possess a high Biological Value.

Incomplete Proteins

Proteins, typically of plant origin, that do not contain all essential and non-essential amino acids and possess a low Biological Value.

Gross Energy (GE)

The total amount of energy released when a feed is completely burnt to its final oxidation products: water, carbon dioxide, and other gases.

Digestible Energy (DE)

Gross energy minus the energy lost in manure ($\text{DE} = \text{GE} - \text{energy lost in manure}$).

Metabolic Energy (ME)

Gross energy minus the energy lost in manure, urine, and fermentation gases ($\text{ME} = \text{GE} - \text{energy lost in manure, urine, and gases}$).

Net Energy (NET)

Gross energy minus the energy lost in manure, urine, fermentation gases, and body heat, used for maintenance, growth, and production.

Nutritive Ratio (NR)

The ratio between digestible protein and digestible non-protein compounds, calculated as: $\text{NR} = 1 : \frac{\%\text{TDN} - \%\text{DP}}{\%\text{DP}}$.

Roughages

Bulky feeds with low weight per unit volume, low digestibility, and high crude fibre content ($>18\%$).

Concentrates

Non-bulky feeds that contain a high percentage of digestible nutrients, high energy or protein value, and low crude fibre content.

Non-Protein Nitrogen (NPN)

Nitrogen sources that are not true proteins (such as urea and biuret) utilized by rumen microbes to synthesize microbial protein.

Maintenance Ration

The amount of feed an animal requires daily simply to maintain its body mass, vital physiological functions, and composition without losing weight.

Production Ration

The feed supplied to an animal above maintenance requirements to support growth, reproduction, lactation, or physical work.

Intensive Production System

A farming system where animals are confined indoors or in paddocks under high stocking densities, high capital input, and controlled environmental conditions.

Extensive Production System

A farming system where animals roam freely over large pastures or veld with minimal human intervention and low capital investment.

Battery Cage System

An intensive housing method for laying hens consisting of small wire cages arranged in rows with automated egg-collection trays.

Flight Zone

The minimum comfort distance an animal attempts to maintain between itself and a perceived threat or handler before moving away.

Crush

A narrow, strong handling facility with high solid sides used to restrain cattle safely during vaccination, examination, or dosing.

Epididymis

A coiled tubular organ adhering to each testis that stores spermatozoa, allows them to mature, and provides passage to the vas deferens.

Vas Deferens

A pair of muscular ducts connecting each epididymis to the urethra for sperm transport during ejaculation.

Bulbo-urethral Glands (Cowper's Glands)

A pair of accessory sex glands along the urethra that produce a clear fluid to neutralize acidity and lubricate the urethra prior to ejaculation.

Spermatogenesis

The biological process in male animals through which diploid spermatogonia undergo mitosis and meiosis to produce mature haploid spermatozoa.

Acrosome

The cap-like organelle covering the anterior half of the sperm head containing digestive enzymes required to penetrate the outer layer of the ovum.

Sterility

The permanent and total inability of an animal to reproduce or generate viable offspring.

Infertility

A temporary condition or reduced capacity that impairs the ability of an animal to reproduce successfully.

Cryptorchidism

A congenital condition where one or both testes fail to descend into the scrotum, remaining in the abdominal cavity.

Azoospermia

The complete absence of viable spermatozoa in the ejaculated semen of a male animal.

Infundibulum

The funnel-shaped opening of the fallopian tube that catches and directs ovulated ova into the oviduct.

Ampulla

The dilated central portion of the fallopian tube where fertilisation of the ovum by a spermatozoon normally occurs.

Cervix

A thick-walled, fibrous sphincter connecting the vagina to the uterus that seals tightly during pregnancy to protect the foetus from infection.

Oogenesis (Ovigenesis)

The cellular process in the female ovary whereby diploid oogonia undergo mitotic and meiotic division to form mature haploid ova.

Oestrus (Heat)

The recurring period in female mammals when they are sexually receptive, fertile, and will allow the male to mount and mate.

Synchronization of Oestrus

The administration of hormonal treatments to manipulate the oestrous cycles of a herd so that multiple females come into heat at approximately the same time.

Artificial Insemination

The manual technique of introducing collected, evaluated, and diluted semen into the female reproductive tract without natural service.

Superovulation

The hormonal stimulation of a genetically superior female (donor) to release a larger number of ova than normal during a single cycle.

Embryo Flushing

The nonsurgical procedure of washing and recovering viable fertilised embryos from the uterus of a donor cow using a sterile catheter and medium.

Cloning (Nuclear Transfer)

The biotechnology of fusing a donor somatic cell nucleus with an enucleated ovum using electrical stimulation to produce a genetically identical organism.

Monozygous Twins

Identical twin offspring derived from the division of a single fertilised ovum (zygote), having the identical genetic makeup and gender.

Dizygous Twins

Non-identical twin offspring derived from the simultaneous fertilisation of two distinct ova by separate spermatozoa.

Freemartin

A sterile, sexually abnormal female calf born co-twin with a male, caused by placental fusion and vascular sharing of anti-Müllerian hormone and testosterone in utero.

Placenta

A vascular organ composed of maternal and foetal membranes (chorion and allantois) that facilitates nutrient, gas, and waste exchange between mother and foetus.

Parturition

The physiological process of giving birth, characterized by rhythmic uterine contractions, dilation of the birth canal, and expulsion of the foetus.

Dystocia

A prolonged, abnormal, or difficult parturition requiring manual assistance or veterinary intervention.

Colostrum

The thick, yellowish first milk secreted by the mammary gland for the first three days after calving, rich in antibodies, minerals, and maternal immunoglobulins.

Dry Period

The non-lactating resting phase (usually 6 to 8 weeks) before calving during which milking is ceased to allow mammary tissue recovery.