Practical implications of pH in Aquaponics for target plant nutrient concentrations derived from Hydroponics
Aquaculture Europe 2022
Allometric Condition Factor
The Allometric Condition Factor (K) is a proportionality coefficient that describes the length-to-weight relationship in fish. It is also widely known as Fulton’s Condition Factor, even though Fulton was not the first to use the condition factor. Equation References
Protein Efficiency Ratio
The Protein Efficiency Ratio (PER) is a measure for the bodyweight increase that can be achieved per unit of protein intake. Equation References
Feed Conversion Ratio
The Feed Conversion Ratio (FCR) is a simple indicator of the conversion efficiency of the given feed into biomass. However, the practical use of the FCR is described as limited because it allows a comparison only based on the absolute amount of feed eaten, but not for the amount of nutrients delivered with the feed …
Absolute Growth
The Absolute Growth (AG) is also commonly termed as Weight Gain (WG). It is frequently used, but without practical use as solitary growth indicator due to its‘ univariate nature. To be interpretable and comparable between observations, it needs to be reported together with a time value. Equation References
Absolute Growth Rate
The Absolute Growth Rate (AGR), sometimes also briefly termed Growth Rate, describes the absolute change of an individuals’ bodyweight per unit of time. Equation References Lugert, V., Thaller, G., Tetens, J., Schulz, C. & Krieter, J. (2016). A review on fish growth calculation: multiple functions in fish production and their specific application. Reviews in Aquaculture …
Relative Growth Rate
The Relative Growth Rate (RGR) describes the relative change of an individuals’ body weight per time unit. Equation References Lugert, V., Thaller, G., Tetens, J., Schulz, C. & Krieter, J. (2016). A review on fish growth calculation: multiple functions in fish production and their specific application. Reviews in Aquaculture 8, 30–42.
Thermal Growth Coefficient
The Thermal Growth Coefficient (TGC) is a better growth metric as it standardises the growth by taking into account the effect of temperature (see e.g. Lugert et al., 2016). However, growth predictions made using the TGC are only valid within an optimum temperature range, as shown by Jobling, 2003. Equation References Jobling, M. (2003). The …
Specific Growth Rate
The Specific Growth Rate (SGR) is the percentage analogue to the Instantaneous Growth Rate (IGR). Lugert et al. (2016) pointed out that it is not suitable for predicting future or past growth. Instead, it is recommended to use the Thermal Growth Coefficient (TGC). Equation References Lugert, V., Thaller, G., Tetens, J., Schulz, C., & Krieter, …
Apparent Digestibility of Nutrients in Feed Ingredients
Equation Outdated equations 1.) Equation by Cho and Slinger, 1982 ADC Cho and Slinger (1982) \[\text{ADC}_{ingr} (\%) = ({\text{ADC}_{test} – i_{ref} \cdot \text{ADC}_{ref} \over i_{ingr}}) \cdot 100\%\] 2.) Equation by Forster, 1999 ADC Forster (1999) \[\text{ADC}_{ingr} (\%) = ({\text{NUT}_{test} \cdot \text{ADC}_{test} – i_{ref} \cdot \text{NUT}_{ref} …
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