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Three trials, with classical experimental designs for in vivo digestibility studies, were conducted to determine the apparent digestibility coe⁄cient (ADC) of protein (ADCp), lipid (ADCl), energy (ADCe) and amino acids (AA) in selected animal by-products fed to European sea bass, Dicentrarchus labrax (Trial 1), gilthead sea bream, Sparus aurata (Trial 2), and turbot, Psetta maxima (Trial 3). In each trial, ¢ve experimental diets [including a reference diet (RD)] where ¢sh meal (FM) was used as the sole protein source were fed ad libitum to the ¢sh for a period of 4 weeks. Test diets were based on the FM RD and obtained by replacing 30% of the RD with a category III designated European animal by-products (¢t for human consumption), namely: steam hydrolysed feather meal (HFM), enzyme-treated feather meal (EFM), poultry meat meal (PMM) and spray-dried haemoglobin meal (SDHM). Faecal material was collected using the 'Guelph system' , and nutrient and energy digestibility coe⁄cients were related to the measurement of chromic oxide (Cr 2 O 3 ) incorporated into the diet at a rate of 0.5%. Without any exception, FM diets yielded the best digestibility values for all macro-nutrients and by all ¢sh. Among the test ingredients, ADCp was consistently higher for PMM and SDHM in the three species (85.5%, 91.1% in sea bass;79.2%, 82.8% in sea bream; and 78.4%, 74.8% in turbot). Conversely, ADCp of HFM and EFM were less e⁄ciently digested (67.2%, 68.2% in sea bass; 21.5%, 21.7% in sea bream; and 46.6%, 36.0% in turbot). However, the novel processing method applied to feather meal did not considerably in£uence the digestibility of most of the nutrients in this feedstu¡. The current investigation yielded valuable numerical ADC for EAA considered to be of prime importance in generating balanced diet formulations.

The early life history is described and compared in the estuarine callianassid shrimp species Lepidophthalmus sinuensis from the Caribbean coast of Colombia and L. louisianensis from the northern Gulf of Mexico, on the basis of laboratory larval cultures and wild plankton collections. Both species have an abbreviated larval development of 2 zoeal stages usually transcended within 3-4 days, with that of L. sinuensis being the shorter and exhibiting greater advancement in the zoeal stages. Development in both species is markedly shorter and morphologically more advanced than in comparable callianassid species for which stages have been described, including most of those known to have only 2 zoeal stages. Larval duration in Lepidophthalmus is nearest that of the ecologically comparable Callianassa s.l. kraussi from southern Africa and suggests possible convergence in early developmental strategies. On the basis of presently known larval histories, genera allied to Lepidophthalmus within the Callichirinae appear to either have long larval histories of 5 zoeal stages, or, if of 2 stages, to bear a morphological resemblance as zoeae to comparable stages in some of the non-Callichirinae. The decapodid (first postlarval) stage is imaginal in form and exhibits burrowing behavior, though appendage development is far short of adult form. Successive early postlarval development and behavior beyond this stage remains unknown. Detailed illustrations of zoeal and decapodid stages are provided to support comparative discussions and for use in larval identifications.

The burrowing ghost shrimp Lepidophthalmus sinuensis Lemaitre and Rodrigues and Lepidophthalmus bocourd (A. Milne Edwards) have significant impacts on pond‐based culture of penaeid shrimp. Marked abbreviation of the larval cycle, an adaptation for estuarine retention in wild populations, favors accumulation of recruits into the same substrates as the parental population where densities of these burrowers sometimes exceed 650 individuals/m2. Higher densities of burrowing shrimp appear to correlate with lower yields of penaeid shrimp because of oxygen requirements by the thalassinids and also bioturbation effects. Rich sources of organic materials in highly reduced pond substrates can be readily exploited by Lepidophthalmus species due to their physiological adaptations to low oxygen concentrations. Bioturbation and ventilatory movement of water through burrowed sediments by ghost shrimp move reduced nutrients into the water column with potential toxic effects on penaeids. Ultimately, activities of these estuarine burrowers oxidize benthic sediments and cycle nutrients into the water column, the negative impacts of which are probably restricted to aquaculture settings.

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