The protein and energy requirements of farmed South African abalone Haliotis midae L. cultured at optimal and elevated water temperatures

Abstract

Formulated abalone feeds used by the culture industry are believed to be unsuitable for use at elevated water temperatures (420 1C).The aim of this study was to develop a feed that could safely be fed to abalone cultured at elevated water temperatures by optimizing dietary protein/energy levels. Abalone (54.90 AE 0.08 mm; 28.99 AE 0.16 g) were cultured at either 18, 22 or 24 1C, and fed diets containing graded levels of protein (18^26%) and energy (11.6^16.2 MJ kg À 1 ). Abalone growth was temperature dependent, declining from 4.33 g month À 1 at 18 1C to 0.77 g month À 1 at 24 1C. Shell length and weight gain were independent of dietary protein, provided that the digestible energy content of the diet was not lower than 13.5 MJ kg À 1 . Dietary energy levels below 13.5MJ kg -1 resulted in signi¢cant reductions in shell growth, weight gain and increased mortality from 5% to 27%. Feed consumption of the 22% and 26% protein diets with 11.6 MJ kg À 1 was signi¢cantly higher (0.53 AE 0.04 and 0.55 AE 0.04% bd. wt. day À 1 respectively) compared with abalone fed the 16.2 MJ kg À 1 diets at the same protein levels (combined mean of 0.45 AE 0.04% bd. wt. day À 1 ) indicating that consumption was linked to energy requirement. The growth and mortality results suggest that abalone cultured at these temperatures have a dietary digestible energy requirement of at least 13.5 MJ kg À 1 .

Inclusion of Distillers Dried Grain as Partial Replacement of Wheat Flour and Soybean Meal in the Diet of Juvenile Abalone Haliotis discus hannai

“…The poor growth rate of abalone has generated the need for more research into optimal nutrition for successful cultures (Fleming et al, 1996), and nutritional demands must be met to produce more efficient cultures (Lee, 2004). Recently, abalone cultures have become increasingly dependent on formulated feeds because of constantly limited supplies of harvested seaweed (Green et al, 2011). A great demand exists for identifying cost-effective ingredients to produce a diet that can maintain abalone growth , and the replacement of soybean meal and wheat flour using more economical ingredients may be beneficial for minimizing feed costs.…”

Effects of wild and farm-grown macroalgae on the growth of juvenile South African abaloneHaliotis midaeLinnaeus

“…The protein contents of wild and farmed U. lactuca used in this study both meet the minimum percentage requirement proposed by Green et al (2011), suggesting that protein alone could not have accounted for the differences observed in the growth rates experienced from these diets. To account for these very different growth rates, we propose two, but not necessarily mutually exclusive, scenarios.…”

“…that portion of the feed gross energy available to the body after the energy costs from excretion have been removed (Fleming 1995b, Britz andHecht 1997). In H. midae, energy loss in the form of excretion has been recorded to range from being negligible (accounting for < 1 % of consumption; Barkai and Griffiths 1988), to a maximum of 15 % (Green et al 2011; determined from Table 1). Thus, the digestible energy from feed available to H. midae can be assumed to be approximately equal to, or very close to the gross energy content.…”

“…Thus, the digestible energy from feed available to H. midae can be assumed to be approximately equal to, or very close to the gross energy content. Bearing this variability in mind, and since Green et al (2011) did not test diets with energy levels between 13.5 and 11.6 MJ kg -1 , we would argue that the farmed U. lactuca probably met the minimum energy requirements for optimal H. midae growth.…”

“…Although studying larger abalone of an initial size of around 50 mm shell length, Green et al (2011) showed that the protein content of formulated feed for H. midae can be dropped as low as 18 % given that the digestible energy of the feed is not lower than13.5 MJ kg -1 . The digestible energy content of food is that portion of the energy that is available to the animal after taking into account the energy costs associated with excretion i.e.…”