Factors Affecting Fish Growth & Performance PDF

Factors affecting fish growth & performance: concepts and definitions AFI32306: Nutrition & Health in aquaculture Johan Schrama 20 March 2023 Factors affecting fish growth & performance: concepts and definitions Why is growth important in aquaculture? Which factors affect growth? Factors affe...

Factors affecting fish growth & performance: concepts and definitions AFI32306: Nutrition & Health in aquaculture Johan Schrama 20 March 2023 Factors affecting fish growth & performance: concepts and definitions Why is growth important in aquaculture? Which factors affect growth? Factors affecting growth Main factors determining growth: • Fish (internal cond.): – species – sex – health – ‘history’ (age, weight, body composition) – genetics (breeding, domestication) • Environment (external cond): – Husbandry: – Water quality: • Feed: √ density √ handling √ feeding method √ ... √ temperature √ oxygen √ metabolites √ ... – level – composition – formulation (ingredients) – type (physical aspects) Factors affecting growth Main factors determining growth: • Fish (internal cond.): – species – sex – health – ‘history’ (age, weight, body composition) – genetics (breeding, domestication) • Environment (external cond): – Husbandry: Which a) b) c) √ density √ handling factor is economically the most important? √ feeding method Feed √ ... – Water quality: √ temperature Fingerlings √ oxygen Water quality management √ metabolites √ ... • Feed: – level – composition – formulation (ingredients) – type (physical aspects) Importance of nutrition in aquaculture Feed cost as percentage of total costs 0 Intensity of aquaculture system Growth description Sigmoid curve After Richter, 1978 Factors affecting growth Weight (g) Weight Maximal growth potential (g) Maximal growth potential Time (days) Internal & external factors Growth ? Feed intake Time (days) Weight (g) Maximal growth potential Time (days) Relation feed intake and growth Realization of growth potential of a fish Feed: Weight •level (g) • composition • physical characteristics Environment: • Husbandry • Water quality Time (days) • …. Health status: • …. Variability of environment (incl.nutrition) and growth Weight Compensatory growth (g) Time (days) Variability of environment (incl.nutrition) and growth Weight (g) Compensatory growth What causes the high growth rate during a period of compensatory growth? 1) Higher feed intake hyperphagia 2) Higher efficiency: Time (days) – Higher digestibility – Lower maintenance – Change in body composition Variability of environment (incl.nutrition) and growth Seasonal variation in growth of sole Energy (kJ) Energy (kJ) Spawning Spawning pre pre post post Egg production Reserves Length Body - basis - Ages (years) quarter Fonds & Rijnsdorp, 1988 Growth curve Discontinuous growth of crustacean Weight (g) How is the curve for total amount of body energy over time? Time (days) Growth curve Discontinuous growth of crustacean Weight (g) How is the curve for total amount of body energy over time? How is the curve for water mass over time? Time (days) Body weight versus growth rate Weight Growth (g) (g/d) Time (days) Feed intake (g/d) Conversion efficiency (CE) Relation feed intake and growth Ropt Rm Ration (% wt/day) Rmax Conversion efficiency (CE) Whichand ration is economically the best? Relation feed intake growth a) Ropt : optimal ration b) Rmax : maximal ration c) Ration below Ropt Ropt Rm Ration (% wt/day) Rmax Relation feed intake and growth Why maintenance different? After Huisman,1974 Relation feed intake and growth Gopt = Gmax Rm Ropt = Rmax Ration (% wt/day) Relation feed intake and growth What are factors causing a curvilinear relationship between growth and feed ration? 1) Experimental errors 2) More feed spillage 3) Change in body composition 4) Growth measured in groups  individual variation in RMAX 5) ... Relation feed intake and growth Conversion efficiency (CE) Growth rate (% body weight.d-1) Gopt = Gmax Rm Ropt = Rmax Ropt = Rmax Ration (% wt/day) Rm Ration (% wt/day) General concept of factors affecting growth Growth rate Growth rate C Factor Factors like: 1) Nutrients (food) 2) Oxygen Growth rate B A Factor Factors like: 1) NH4+ 2) CO2 3) Toxines 4) ..... Factor Factors like: 1) Temperature 2) pH 3) Stocking density 4) ..... Interaction between factors affecting growth Growth rate Growth rate C Feed ration Growth rate B A Feed ration Feed ration