Year 12 Agriculture Notes: Plant and Animal Production

A single comprehensive array containing 500 practice flashcards in question and answer style based on the provided agricultural lecture transcript, covering animal production, plant production, sustainable land use, and agribusiness.

What is the definition of digestion in agriculture?

The process by which food molecules are broken down into small soluble molecules for absorption into the bloodstream.

What specific energy sources must be supplied to a monogastric animal?

Carbohydrates (sugars, starches), proteins, lipids, minerals, and vitamins.

Why can monogastric animals not digest cellulose?

They lack the necessary microbes and enzymes to break down the fibrous material.

What is the approximate pH of a monogastric animal's stomach?

$$pH\,2$$

Which enzyme acts in the monogastric stomach alongside Hydrochloric acid ($HCl$)?

Pepsin

How many stomachs do ruminant animals have?

Four

What is the largest compartment of the ruminant stomach?

The Rumen

What are the three types of micro-organisms found in the rumen?

Bacteria, protozoa, and fungi.

What is the ideal pH range of 'rumen liquor'?

$$pH\,6-7$$

At what temperature is the rumen typically maintained?

$$38-40^{\circ}\text{C}$$

Which gases are the primary by-products of carbohydrate digestion in the rumen?

Methane ($CH_4$) and Carbon Dioxide ($CO_2$).

What is the agricultural term for the buildup of gas in the rumen?

Bloat

In the rumen, what are simple sugars metabolized into for absorption?

Volatile Fatty Acids (VFAs)

How are VFAs absorbed from the rumen into the bloodstream?

Via papillae lining the walls of the rumen.

Into what components do microbes break down proteins in the rumen?

Peptides and amino acids.

What byproduct of protein breakdown can be secreted in saliva or urine after conversion to urea?

Ammonia

Which two vitamins are synthesized by microbes in the rumen?

Vitamin B and Vitamin K

What is the function of the Reticulum?

It is a smaller compartment with a similar fermentation function that precedes the Omasum.

What is the nickname for the Omasum due to its page-like folds?

'The Bible'

What percentage of water is removed from the rumen liquor in the Omasum?

$$60-70\%$$

Which compartment is considered the 'true' stomach of a ruminant?

The Abomasum

What occurs in the Abomasum to facilitate digestion?

$HCl$ and enzymes break down undigested protein and dead microbes.

What determines the closing of the oesophageal groove in young ruminants?

The action of suckling.

Where does the oesophageal groove connect in a young lamb?

From the end of the oesophagus to the Omasum.

Why do young ruminants not initially use the rumen or reticulum?

Because they are on a milk-based diet.

What is an advantage of the Monogastric digestive system regarding feed conversion?

A more effective Food/Product Conversion Ratio (FCR).

What is an advantage of the Ruminant system regarding food quality?

Low quality feed is improved by microbial synthesis.

What is a disadvantage of the Monogastric system regarding fiber?

It cannot digest cellulose.

What is a disadvantage of the Ruminant system regarding energy efficiency?

It is an inefficient process with energy lost through heat and gas production.

Which nitrogen source can ruminants use to synthesize protein?

Urea

Which group of animals requires a more expensive and 'complete' feed supply?

Monogastrics

Which enzyme in monogastric saliva breaks down starch?

Amylase

Unlike monogastrics, ruminants have teeth only on which palate?

The bottom palate.

What component in ruminant saliva acts as a pH buffer?

Bicarbonate

What is the primary method of movement in the oesophagus for both systems?

Peristalsis

What is the ruminant process of re-chewing fibrous food called?

Regurgitation

What is the effect of rumen microbes on fed fat?

Fat fed is altered by microbes in the rumen.

Where do bile from the liver and pancreatic juices mix with digested material?

The Duodenum

What structures line the small intestine to increase surface area for absorption?

Villi

What is the function of the Large Intestine?

Water is removed from the digestive matter.

Where is undigested material stored before excretion?

The Rectum

What is an Extensive Feeding System?

Animals are fed on a grazing system depending on grasses and legumes.

What characterizes an Intensive Feeding System?

High stocking rates in a feedlot with controlled rations of grains and supplements.

How can producers manipulate a cattle carcase to be lean-muscled?

By feeding heavily at a young age and then limiting feed later in maturity.

What is the formula for Feed Conversion Ratio (FCR)?

$$\text{Mass Eaten} / \text{Weight Gained}$$

What is the standard FCR for ruminant efficiency mentioned in the notes?

$$8\,kg\,food / 1\,kg\,weight$$

How does succulent pasture affect intake and energy content?

It leads to a higher intake rate but lower energy content.

Define 'Roughages' in cattle nutrition.

Feeds with high fiber, low digestibility, high moisture, and less energy.

Define 'Concentrates' in cattle nutrition.

Feeds with high energy, high protein, and low fiber.

What is 'marbling' in beef cattle?

Intramuscular fat promoted by concentrate diets.

What condition is prevented by weaning cattle onto concentrates slowly?

Lactic acidosis

What are the chemical elements found in proteins (standard set)?

CHON (Carbon, Hydrogen, Oxygen, Nitrogen) and sometimes S (Sulfur).

What is 'By-pass protein'?

Protein that is not metabolized by microbes and passes directly to the Abomasum.

What metabolic products provide energy from carbohydrates in the rumen?

VFAs (Volatile Fatty Acids)

What is the primary role of lipids in a ruminant diet?

They provide large amounts of energy but are not strictly required.

In terms of fertility, what does good nutrition promote in cows?

Regular oestrus cycles and high fertility rates.

Why is excessive grain-feeding detrimental to bulls at joining?

Over-fat bulls are less willing to mate and may have health complications.

What is 'Gross Energy' (GE)?

The total amount of energy contained in the food.

What is 'Metabolisable Energy' (ME)?

The energy left after losses in waste products (methane, $CO_2$, etc.).

What is 'Net Energy' (NE)?

The energy used to keep the animal alive, minus energy used as body heat.

In what units is ME requirement measured for ruminants?

$$MJ/day$$

What is the estimated energy requirement for a $500\,kg$ lactating cow?

$$156\,MJ/day$$

What is the difference between 'Growth' and 'Development'?

Growth is an increase in size/weight; Development is a change in body proportions/tissue types.

What tissues are the first to develop in a calf in the womb?

Bone, organs, and nerves.

As cattle mature, how does the proportion of bone change?

The proportion of bone decreases.

What happens to muscle proportion relative to bone as cattle mature?

It increases and then stabilizes.

When does fat develop in the cattle growth sequence?

After maturity, if the plane of nutrition remains high.

What are the muscle scoring grades used for carcases?

$A$ (heavy) to $E$ (light).

What are the fat scoring grades for beef carcases?

$1$ (lean) to $6$ (fat).

Name two representative 'Early Maturing' cattle breeds.

Angus and Hereford.

Name two representative 'Late Maturing' cattle breeds.

Charolais and Simmental.

Which sex of cattle lays down the most fat earliest?

Female

Which tissue is most affected by poor nutrition in cattle?

Fat (because it is the last developing tissue).

What shape describes the typical growth curve of a cattle herd?

A stretched 'S' shape.

At what stage does an animal have its most efficient FCR?

At puberty.

What is 'Liveweight'?

The weight of the animal before slaughter.

Where is the P8 site located for fat score measurement?

On the rump.

What is 'Hot Standard Carcase Weight' (HSCW)?

The weight of the 'dressed' carcase.

Define the 'Dressing %' formula.

$$\frac{\text{Carcase weight}}{\text{Liveweight}} \times 100$$

What term describes identical alleles in a gene pair?

Homozygous

What is a negative effect of high homozygosity in animals?

Decreased productivity, slower growth, and vulnerability to disease.

What is 'Hybrid Vigour'?

Higher production and growth rates in offspring than either parent due to heterozygosity.

What is the goal of 'Inbreeding'?

To produce a uniform line of animals by encouraging homozygous pairs.

What is 'Line Breeding'?

Mating involving a common ancestor over generations to limit the gene pool.

What is 'Outbreeding'?

Breeding completely unrelated animals of the same breed.

What is 'Crossbreeding'?

Breeding completely unrelated animals of different breeds.

By what percentage can crossbreeding increase weaning weight?

Up to $14\%$

What biological process produces gametes?

Meiosis

Which glands belong to the endocrine system for animal reproduction?

Gonads, Placenta, Pituitary gland, and Hypothalamus.

What is the function of Follicle Stimulating Hormone (FSH) in females?

Stimulates the growth of Graafian follicles in the ovaries.

Where is Luteinising Hormone (LH) produced?

Anterior Pituitary

What is the role of Oestrogen produced by ovary follicles?

Causes FSH reduction, triggers LH release, and maintains the reproductive tract.

What is the role of Progesterone?

Inhibits FSH, develops the uterus wall, and maintains pregnancy.

Which hormone stimulates milk release (let-down) in lactating animals?

Oxytocin

What hormone stimulates the cells of Leydig to produce testosterone?

Luteinising Hormone (LH)

What are the signs of Oestrus in cows?

Restlessness, bellowing, mounting other cows, and muddy flanks.

What is 'Libido' in male cattle?

The male's interest and ability in serving females.

Define 'Dystochia'.

Difficult birth, often caused by overfeeding or oversized offspring.

How many males are typically provided for every 100 females in sheep and cattle?

3 males.

What is 'Oestrogenic Infertility' in ewes?

Infertility caused by eating high oestrogen pasture like subterranean clover.