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Energy conversion and Feed conversion ratio (FCR (A low feed conversion…
Energy conversion and Feed conversion ratio
Biomass is the total dry weight of organic matter in organisms or ecosystems
The percentage of energy that is converted into biomass is dependent upon a number of factors:
Energy is lost as inedible materials – such as bones, teeth and hair
Energy is lost via excretion of undigested and unabsorbed materials
Energy is lost as heat from cellular respiration (higher respiration rate results in more heat lost)
Primary and secondary production
Primary production
The main source of energy for primary production is sunlight, but a fraction may be driven by chemosynthesis by lithotroph
Gross primary production (GPP) is the amount of chemical energy as biomass that a producer creates in a given length of time
Net primary production (NPP) is the amount of chemical energy that is not consumed by respiration (NPP = GPP – respiration)
Secondary production
Secondary production describes the generation of biomass by heterotrophic organisms (consumers)
This biomass generation is driven by the transfer of organic compounds between trophic levels via feeding
Secondary production may also be categorised according to gross (total) and net (usable) amounts of biomass
FCR
Feed conversion ratios measure the efficiency of an animal in converting the food provided (feed mass) into a desired output
Feed Conversion Ratio (FCR) = mass of feed ÷ mass of desired output
The lower the feed conversion ratio the more efficient the method of food production
A low feed conversion ratio is obtained by minimising the potential losses of energy for the animal stock
While more efficient food production practices lower costs, there are a number of potential ethical issues that may be involved
