Effect of Different Doses of Rabbit Manure on the Abundance, Growth Rate and Production of Zooplankton in Plurispecific System for Fish Larvae Feeding

Abstract

In order to determine the optimal dose of rabbit manure for plurispecific production of fresh water zooplankton in controlled area, the effects of six different doses of dry rabbit manure (T1 = 300 g/m 3 , T2 = 600 g/m 3 , T3 = 900 g/m 3 , T4 = 1200 g/m 3 , T5 = 1500 g/m 3 , T0 = 0g/m 3 ) on physico-chemical and biological parameters of areas were monitored for 27 days in cultures realized in plastic buckets of 80 L capacity each. Manures are from rabbits fed with diet previously revealed favorable to their growth, and is made of 2% of dried cassava, 30% of maize bran, 10% of palmist cake, 10% of soya cake, 5% of cotton cake, 2% of shell, 10% of malt, 5% of beer yeast, 10% of Panicum maximum and 1% of salt. Six days after fertilization, buckets were seeded with zooplankton by 26 individuals per liter (ind/L). Results obtained show that the supply of rabbit manure has improved chemical properties and microalgae production (phytoplankton) with treatments T1, T2, T3, T4 and T5. Optimal conditions of zooplankton production through phytoplankton are obtained with doses in T2 and T4 which present the best specific growth rate. The daily production through the highest phytoplankton biomass (chlorophyll-a) has been obtained with dose in T5. Thus, doses 600 g/m 3 and 1200 g/m 3 of rabbit manure may be considered optimal for a plurispecific production of fresh water zooplankton. It was noted that Rotifers were predominant in abundance in almost the different culture areas.Keywords Rabbit manure; Optimal dose; Zooplankton; Plurispecific production BackgroundThe natural feed appreciated by fish larvae is essentially made of zooplankton and artificial dry feed are not always appropriated to this premature stage (Arimoro, 2005). Consequently, zooplankton such as cladocerans, copepods and rotifers are used for larval rearing by many researchers in controlled area (Awaïss et al., 1992). Artemia (live food) is the most used for certain marine species whose hatching, development and growth were realized in pond (Agadjihouèdé et al., 2011). Nevertheless, it remains less effective in fresh water fish larvae. Artemia as larvae food is inaccessible to rural fish farmers (Fiogbe et al., 2003). Indeed, its use doesn't always give good zootechnical performances to fresh water fishes. Zooplankton production in controlled area is carried out in many studies, by the way of phytoplankton production using different types of fertilizer (chemical, organic genuine vegetal or animal) (Adande et al., 2015). Chemical fertilizers (minerals) are the former used for phytoplankton production for the purpose of zooplankton production (Boyd et al., 2008) while organic fertilizers genuine vegetal or animal are the second used (Dalme et al., 2011). Between these two categories of fertilizer, the first type is dangerous to the environment and also expensive while the second type is less expensive and does not present any risk for the environment (Agadjihouèdé et al., 2011;Adande et al., 2017). These findings justify nowadays the easy use of organic...