Factorial Approach to Determining Energy and Protein Requirements of Gilthead seabream (<i>Sparus aurata</i>) for Optimal Efficiency of Production

Requirements for dietary energy and protein in growing fish can be quantified using the factorial approach which assumes that the requirement is the sum of growth and maintenance. Thus dietary intake can be calculated using the respective partial efficiencies of utilization. Growth for gilthead seabream as a function of body weight and temperature was predicted by the equation: y = 0.92 · BW (kg) 0.613 · e 0.065 · T (where y = weight gain in g fish-1 day-1, BW = body weight in kg and T = temperature in 0C). The composition of the gain was measured by analyzing whole fish ranging from 1 to 420g. The energy content was dependent upon fish weight and increased from 5.0 to 11.0 MJ kg-1 body mass, whereas the protein content remained constant at 177g kg-1. The comparative slaughter technique was used to determine the loss in the fish during starvation and the values amounted to 42.5 kJ BW(kg) -0.83 day-1 and 0.42g BW(kg) -0.70 day-1 for energy and protein respectively. The efficiencies of utilization of digestible energy (DE) and digestible protein (DP) for maintenance and growth were determined by feeding seabream of two sizes at increasing feeding levels, from zero to maximum voluntary feed intake. To estimate optimal protein utilization for protein deposition seabream were fed diets formulated to contain varying DCP/DE ratios (34 - 15g MJ-1) in three consecutive trials. Fish were hand-fed to apparent satiation and the subsequent energy and protein gain were measured. The requirement for digestible energy for maintenance was determined to be 53.0 kJ BW(kg) -0.83 day-1 and for digestible protein 0.77g BW(kg) -0.70 day-1. The relationship between DE intake and energy gain was found to be constant at a value of kDEg = 0.56 and was independent of feed intake, body weight and DCP/DE ratio. Efficiency of protein utilization for growth varied between 0.33 and 0.56 depending on the DCP/DE ratio in the diet and optimal protein utilization for protein deposition was estimated to be kP = 0.48. Using these values allows optimization of practical feeding tables for seabream culture.Faktorielle Berechnung des Energie- und Proteinbedarfs von Goldbrassen (Sparus aurata) zur Optimierung der praktischen FütterungDer Bedarf wachsender Fische an Energie und Protein im Futter läßt sich mit Hilfe der faktoriellen Methode quantifizieren, die den Bedarf als Summe aus Wachstum und Erhaltung unterstellt. Die Aufnahme über das Futter kann daher unter Verwendung der jeweiligen partiellen Wirkungsgrade kalkuliert werden. Das Wachstum von Goldbrassen wurde als Funktion von Körpergewicht und Temperatur mit Hilfe der folgenden Gleichung berechnet: y = 0,92 · BW(kg) 0,613 · e 0,065 · T (mit y = Gewichtszunahme in g Fisch-1 Tag-1, BW = Körpergewicht in kg und T = Wassertemperatur in °C). Die Zusammensetzung des Gewichtszuwachses wurde durch Ganzkörperanalysen von Fischen im Gewichtsabschnitt von 1 bis 420 g bestimmt. Der Energiegehalt hing vom Gewicht des Fisches ab und stieg von 5,0 auf 11,0 MJ je kg Körpermasse an, während der Proteingehalt mit 177 g je kg konstant blieb. Mit Hilfe der vergleichenden Schlachttechnik wurde der Gewichtsverlust der Fische während einer Hungerperiode bestimmt. Die Werte betrugen 42,5 kJ BW(kg) -0,83 Tag-1 für Energie, beziehungsweise 0,42 g BW(kg) -0,70 Tag-1 für Protein. Die Wirkungsgrade für Erhaltung und Wachstum wurden für verdauliche Energie (DE) und verdauliches Protein (DP) bestimmt, indem Goldbrassen von zwei unterschiedlichen Größen zunehmende Futtermengen erhielten und zwar von Null bis zur maximalen freiwilligen Futteraufnahme. Zur Schätzung der optimalen Proteinausnutzung für den Proteinansatz erhielten Goldbrassen in drei aufeinanderfolgenden Versuchen Futter mit unterschiedlichem DCP/DE - Verhältnis (34 -15 g je MJ). Die Fische wurden per Hand bis zur offensichtlichen Sättigung gefüttert und der anschließende Energie- und Proteinansatz gemessen. Es wurde ein Erhaltungsbedarf an verdaulicher Energie in Höhe von 53,0 kJ BW (kg) -0,83 Tag-1, sowie an verdaulichem Protein in Höhe von 0,77g BW(kg) -0,70 Tag-1 ermittelt. Die Beziehung zwischen der Aufnahme an DE und Energieansatz erwies sich als konstant mit einem Wert von kDEg = 0,56 und war unabhängig von Futteraufnahme, Körpergewicht und DCP/DE-Verhältnis. Die Effizienz der Proteinausnutzung variierte zwischen 0,33 und 0,56 in Abhängigkeit vom DCP/DE-Verhältnis in der Ration. Die optimale Proteinausnutzung für Proteinansatz wurde als kP = 0,48 errechnet. Die Verwendung dieser Werte ermöglicht eine Optimierung der Fütterungstabellen für die praktische Fütterung bei der Haltung von Goldbrassen

Using microalgae in the circular economy to valorise anaerobic digestate::Challenges and Opportunities

Managing organic waste streams is a major challenge for the agricultural industry. Anaerobic digestion (AD) of organicwastes is a preferred option in the waste management hierarchy, as this processcangenerate renewableenergy, reduce emissions from wastestorage, andproduce fertiliser material.However, Nitrate Vulnerable Zone legislation and seasonal restrictions can limit the use of digestate on agricultural land. In this paper we demonstrate the potential of cultivating microalgae on digestate as a feedstock, either directlyafter dilution, or indirectlyfromeffluent remaining after biofertiliser extraction. Resultant microalgal biomass can then be used to produce livestock feed, biofuel or for higher value bio-products. The approach could mitigate for possible regional excesses, and substitute conventional high-impactproducts with bio-resources, enhancing sustainability withinacircular economy. Recycling nutrients from digestate with algal technology is at an early stage. We present and discuss challenges and opportunities associated with developing this new technology

Nutrition and feeding of Sparidae

Oliva-Teles, A., Lupatsch, I. and Nengas I. (2011) Nutrition and feeding of Sparidae. In: Sparidae – Biology and Aquaculture of gilthead seabream and other species. Pavlidis, M.A. and Mylonas, C.C. (Eds). Wiley-Blackwell, UK, p 199 – 232

Successful Replacement Of Fishmeal By Plant Proteins In Diets For The Gilthead Seabream, Sparus Aurata L.

Soy protein concentrate, wheat gluten, and corn gluten meal were evaluated in combination and as sole dietary protein sources in diets for gilthead seabream. A growth trial and digestibility determinations demonstrated the effectiveness of these plant proteins as alternatives to fish- meal. Digestibility trials indicated superior protein digestibility for soy protein (92%), wheat gluten (96%), and corn gluten (90%) in comparison with fishmeal (86%), while energy digestibility was higher than fishmeal (84%) only in wheat gluten (91%; it was 75% for soy protein and 72% for corn gluten). For the growth trial, eight isonitrogenous and isoenergetic (as-fed basis) diets were formulated with differences in the protein sources. Growth in the range of 40-130 g was superi- or to the fishmeal control with the diet containing wheat gluten but inferior in the diets containing soy protein concentrate or corn gluten meal. Diets that replaced 25-100% of the fishmeal with a mixture containing equal portions of all three plant proteins outperformed the control with a 9- 16% greater weight gain and 4-10% lower feed conversion ratio. The use of soy protein or corn gluten as the sole protein source in diets for seabream is not recommended but their use in com- bination with wheat gluten can provide a partial or complete alternative to fishmeal. However, the cost of supplemental arginine made replacement economic at only the lowest replacement level (25%). An in-depth evaluation of the need for this amino acid in the protein mixture could signif- icantly affect the feasibility of using higher replacement levels

Studies on energy and protein requirements to improve feed management of the Pacific white shrimp, Litopenaeus vannamei.

Lupatsch, I., Cuthbertson, L., Davies, S. and Shields, R.J. (2008). Studies on energy and protein requirements to improve feed management of the Pacific white shrimp, Litopenaeus vannamei. In: Avances en Nutrición Acuícola IX. IX Simposio Internacional de Nutrición Acuícola. 24-27 Noviembre. Editors: Cruz Suárez, L.E., Marie,D.R., Salazar, M.T., López, M.G.N., Cavazos, D.V.A., Lazo, J.P. and Viana, M.T. p. 281- 295

Predicting growth, feed intake and waste production of intensively reared tilapia based on nutritional bioenergetics.

Lupatsch, I. (2008). Predicting growth, feed intake and waste production of intensively reared tilapia based on nutritional bioenergetics. In: Proceedings of the Seventh International Conference on Recirculating Aquaculture Roanoke, Virginia, July 2008. p. 306 – 314