Welcome to Food Production: Animals on the Land
Welcome to your study notes for Unit 2: Animals on the Land! In this chapter, we explore how commercial livestock produce the food on our plates—ranging from milk and beef to eggs and bacon. We will break down how farm animals digest their food, how farmers select breeding traits, how diseases are controlled, and how farming affects the environment and farm finances.
Don't worry if this seems like a lot to learn at first! Take it step-by-step. Use the summaries, analogies, and memory aids along the way to build your confidence for the exam.
---1. Commercial Livestock Sectors
Across the UK and Northern Ireland, livestock farming is divided into four primary commercial sectors: cattle, sheep, pigs, and poultry.
A. Cattle: Dairy vs. Beef
Cattle are bred for two distinct purposes: producing milk (dairy) or producing meat (beef).
Dairy Breeds:
• Main breeds include Holstein-Friesian and Jersey.
• Selected for high milk yield (total volume) and milk quality (high percentages of butterfat and protein).
Beef Breeds:
• Main breeds include Hereford, Aberdeen Angus, Limousin, Charolais, and Belgian Blue.
• Key Traits Selected in Beef Cattle:
1. Daily Liveweight Gain (DLWG): How much weight an animal puts on each day.
2. Killing-Out Percentage: The proportion of the live animal that becomes saleable meat carcass.
3. Muscling/Conformation: The shape and meat yield of the animal (for example, the double-muscling trait in Belgian Blues).
4. Ease of Calving: Cows giving birth without veterinary assistance or complications.
B. Sheep: Hill/Upland vs. Lowland Systems
Sheep systems depend heavily on the land type and climate:
• Upland and Hill Systems: Tougher terrain and harsher weather. Farmers select hardy breeds for maternal hardiness, weather resistance, and fleece quality.
• Lowland Systems: Better grazing and milder weather. Focus is placed on fast growth rates and a high lambing percentage (also known as prolificacy—the number of lambs born per ewe).
C. Pigs
Pigs are monogastric animals (single-chambered stomach) raised indoors or outdoors for pork and bacon.
• Key Production Targets: Large litter sizes and a high Feed Conversion Ratio (FCR) (how efficiently the pig turns animal feed into body mass).
D. Poultry: Layers vs. Broilers
• Layers: Birds bred specifically to lay unfertilised table eggs (e.g., Rhode Island Red and modern hybrid layer strains).
• Broilers: Birds bred for rapid growth and high lean meat yield.
Quick Review: Dairy = milk yield/quality; Beef = DLWG, muscling, and killing-out %; Sheep = hardiness (upland) vs prolificacy (lowland); Poultry = layers (eggs) vs broilers (meat).
---2. Animal Digestive Systems & Nutrition
Farm animals have adapted different digestive systems depending on what they eat.
A. Ruminants (Cattle & Sheep)
Ruminants have a complex four-chambered stomach designed to break down tough plant material (cellulose) found in grass and silage.
The Four Chambers in Order:
1. Rumen: A large fermentation vat where billions of microbes (bacteria and protozoa) ferment and break down plant cellulose.
2. Reticulum: A pouch with a honeycomb-like lining that helps form cud and regurgitates food back to the mouth for re-chewing.
3. Omasum: A chamber with many folds that absorbs water and volatile fatty acids.
4. Abomasum: The "true" stomach, which secretes acid and digestive enzymes to break down proteins, just like a human stomach.
Memory Trick: Remember the order with the phrase "Red Robots Order Apples" (\(\text{Rumen} \rightarrow \text{Reticulum} \rightarrow \text{Omasum} \rightarrow \text{Abomasum}\)).
B. Monogastrics (Pigs)
Pigs have a simple, single-chambered stomach (like humans) that relies on enzymes and stomach acid to digest feed. They cannot digest high-fibre grass effectively and require concentrated feeds containing cereals and soya.
C. Avian Digestive System (Poultry)
Chickens do not have teeth to chew their food, so their digestive tract uses specialized organs:
• Oesophagus: Moves food from the beak to the crop.
• Crop: A temporary storage pouch that softens and moistens food.
• Proventriculus: The glandular stomach where digestive acids and enzymes are added.
• Gizzard (Ventriculus): A thick, muscular organ that grinds hard grains using swallowed stones/grit.
• Small & Large Intestine: Digestion and nutrient absorption.
• Cloaca: The single exit chamber for digestive waste, urine, and egg laying.
Common Exam Pitfall: Do not confuse the crop (which stores and softens feed) with the gizzard (which grinds feed using grit)!
D. Animal Nutrition: Rations
Farmers balance feed using two key categories of feed rations:
• Maintenance Ration: The minimum amount of feed energy and nutrients needed to keep an animal alive, warm, and at a steady body weight without losing or gaining mass.
• Production Ration: The extra feed supplied above maintenance requirements to support productive outputs—such as milk lactation, muscle growth, egg production, or fetal development.
3. Breeding Technologies & Genetics
Farmers select breeding animals to pass desirable genetic traits onto the next generation.
A. Selective Breeding Traits
Traits commonly selected include: high milk yield, high butterfat and protein %, lean meat conformation, disease resistance, docility (calm temperament), longevity, and calving ease.
B. Artificial Insemination (AI)
Artificial Insemination (AI) is the process of collecting semen from a top-quality, tested male and inserting it manually into the female reproductive tract at the correct stage of heat (oestrus).
Advantages of AI:
• Gives farmers access to superior, proven genetics from worldwide sires at a fraction of the cost of buying the animal.
• Reduces the risk of spreading venereal/reproductive infections between animals.
• Improves farm safety by eliminating the need to handle aggressive breeding bulls or rams on the farm.
Limitations of AI:
• Requires skilled labour and careful heat/oestrus detection.
• Less practical in extensive, free-roaming hill and upland sheep systems where gathering animals daily is difficult.
4. Animal Health, Biosecurity & Veterinary Medicines
A. Major Farm Animal Diseases
• Bovine Tuberculosis (bTB): Caused by the bacterium Mycobacterium bovis. It causes respiratory damage, coughing, and weight loss. bTB results in mandatory culling of infected "reactor" cattle, strict movement bans/quarantines on herds, and trade barriers, creating huge financial losses.
• Mastitis: A bacterial infection of the udder in dairy cows. It causes painful swelling, reduces milk yield, spoils milk quality, and increases the Somatic Cell Count (SCC).
• Liver Fluke: Caused by the parasitic flatworm Fasciola hepatica. It damages the liver in cattle and sheep. It requires the small mud snail as an intermediate host to complete its lifecycle. Controlled by anthelmintic drenches and draining wet pastures.
• Salmonella: A bacterial disease causing gut infections; monitored in poultry systems to protect human food safety from contaminated eggs or meat.
• Pneumonia: A respiratory infection common in housed calves and pigs, often triggered by damp conditions and poor shed ventilation.
B. Biosecurity vs. Physical Security (Examiner Focus!)
Make sure you do not mix these two terms up in your exam:
• Biosecurity: Measures taken to prevent the introduction and spread of pathogens and diseases (e.g., disinfectant footbaths, quarantine pens for newly bought stock, clean transport vehicles, and pest-proof feed stores).
• Physical Farm Security: Measures taken to prevent theft or vandalism (e.g., locks, boundary fences, CCTV, and farm gates). Physical security is not biosecurity!
C. Safe Medicine Handling & Withdrawal Periods
• Storage: Veterinary medicines must be stored in a locked cabinet at the recommended temperature (e.g., refrigerated if required).
• Record-Keeping: Farmers must record the animal ID, date of treatment, medicine name, batch number, dose given, and the date the withdrawal period ends.
• Withdrawal Period: The statutory minimum time that must pass between the last administration of a medicine and the slaughter of the animal (or the collection of its milk/eggs) for human consumption. This ensures no chemical residues enter the human food supply.
5. Farm Economics & Environmental Interactions
A. Farm Profit Equation
To stay in business, a farm enterprise must remain profitable. The basic financial calculation is:
\(\text{Profit} = \text{Total Income} - \text{Total Costs}\)
• Total Income: Money made from sales of milk, livestock, wool, or eggs.
• Total Costs: Money spent on feed, bedding, veterinary bills/medicines, housing, machinery, and labour.
B. Slurry Runoff, BOD, and Eutrophication
If animal slurry or silage effluent escapes into local rivers or lakes, it causes severe environmental damage through a process called eutrophication.
Step-by-Step Eutrophication Process:
1. Nutrient-rich slurry enters the river/lake.
2. High levels of nitrogen and phosphorus trigger a rapid growth of algae (algal bloom).
3. The algae block sunlight, then die off as nutrients run out.
4. Decomposing aerobic bacteria multiply rapidly to break down the dead algae.
5. These bacteria consume dissolved oxygen from the water.
6. The Biological Oxygen Demand (BOD) rises sharply, meaning oxygen levels drop, causing fish and aquatic life to suffocate and die.
Definition of BOD:
Biological Oxygen Demand (BOD) is the measure of the amount of dissolved oxygen required by aerobic microorganisms to break down the organic material present in a body of water.
C. Remediation: Reed-Bed Filtration
Farmers can treat lightly contaminated farmyard runoff using a natural reed-bed filtration system:
• Runoff passes through constructed gravel beds planted with common reeds.
• Microbes living on the reed roots break down organic pollutants.
• The reeds absorb excess nutrients (nitrogen and phosphorus), leaving clean water to discharge safely into the environment.
Quick Revision Checklist
Before sitting your Unit 2 exam, check that you can:
• Name common dairy (Holstein-Friesian, Jersey) and beef (Hereford, Angus, Limousin, Charolais, Belgian Blue) breeds.
• Explain what DLWG, killing-out %, and FCR mean.
• List the four ruminant stomach chambers in correct order: Rumen, Reticulum, Omasum, Abomasum.
• State the functions of the avian crop (softens/stores feed) and gizzard (grinds feed with grit).
• Distinguish between maintenance rations and production rations.
• Explain the advantages and limitations of Artificial Insemination (AI).
• Define biosecurity and explain why it is different from physical farm security.
• State what a withdrawal period is and why it protects consumers.
• Explain the steps of eutrophication and define Biological Oxygen Demand (BOD).