ARTICLE FEED & ADDITIVE MAGAZINE February 2024 67 the amount of total energy available, with respect to which the fish distributes all its energy to different activities on a preferential basis from basic needs to reproduction and therefore this will form the important discussion of the article. ENERGY DISTRIBUTION The energy requirements of the animal vary in quantity according to the species, feeding habits, size, environment and reproductive state, water quality, stress etc. Since all biological systems obey the laws of thermodynamics, the energy balance equation in fishes is represented as; C=P+R+U+F An energy budget is the amount of energy in terms of percentage of ingested food that is utilized for each major process by fish such as growth, reproduction, digestion, respiration, urinary and faecal production. A generalized energy budget for young carnivorous and herbivorous fishes fed on natural food has been developed by Brett & Groves, 1979. Carnivores: 100 C = 29P + 44R + 7U + 20F Herbivores: 100 C = 20P + 37R + 2U + 4 1F The interplay between the fish's feeding behaviour, metabolic rates, and environmental factors influences the overall energy budget and, subsequently, growth, reproduction, and fitness. Fish that are well-fed tend to allocate more energy towards growth and reproduction, while those facing food shortages may prioritize maintenance and reduce investment in these other functions. Energy distribution in fishes is influenced by a variety of internal and external factors like metabolic needs of the fishes, feeding level, type of feed, feed availability, quality and quantity of food taken in, feeding habit, feeding behaviour, temperature, age, size, sex, life stage, reproductive needs, level of activity, prey-predator relationship, competition, state of health, oxygen level, level of Figure 1. Energy Allocation Scheme
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