Explain why farmers who rear livestock often use indoor housing and controlled feeding programmes to increase the efficiency of energy transfer to meat production.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Modern livestock farming uses techniques such as keeping animals indoors in warm buildings and limiting their movement. These practices are designed to improve the efficiency of food production.
Model answer (5 marks)
Animals lose energy as heat to the environment through respiration and evaporation. By keeping livestock indoors in warm buildings the temperature difference between the animal and its surroundings is reduced, so less energy is required to maintain body temperature. Limiting the animals’ movement also reduces the energy expended in muscle contraction and locomotion. Consequently a larger proportion of the energy obtained from feed is available for growth and biomass production. This increases the efficiency of energy transfer from feed to meat, meaning less feed is needed per kilogram of meat produced and the farmer obtains more meat from the same amount of feed.
Examiner tips
- Use the exact terms: ‘energy transfer’, ‘biomass’, ‘feed efficiency’.
- Show the causal chain: less heat loss → less maintenance energy → more growth energy → higher efficiency.
Common mistakes
- Confusing heat loss with metabolic heat production; forgetting to mention respiration as a heat source.
- Using vague phrases like ‘better conditions’ without linking to energy balance.
Mark scheme (5 marks)
- Animals lose energy/heat to the environment through respiration
- Keeping animals warm reduces the temperature difference between the animal and its surroundings, so less energy is used maintaining body temperature
- Limiting movement reduces the energy used in muscle contraction / reduces energy used for movement
- More of the energy from food is therefore available to be transferred into biomass / growth
- This increases the efficiency of energy transfer (from feed to meat), so less feed is needed per kilogram of meat produced / the farmer gets more meat for the same amount of feed
Key terms in this question
Related
- All AQA A-Level Biology (7402) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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