Deformed Larvae (deformed + larva)

Distribution by Scientific Domains


Selected Abstracts


A balanced amino acid diet improves Diplodus sargus larval quality and reduces nitrogen excretion

AQUACULTURE NUTRITION, Issue 5 2009
M. SAAVEDRA
Abstract Fish larvae present high amino acid requirements due to their high growth rate. Maximizing this growth rate depends on providing a balanced amino acid diet which can fulfil larval amino acid nutritional needs. In this study, two experimental microencapsulated casein diets were tested: one presenting a balanced amino acid profile and another presenting an unbalanced amino acid profile. A control diet, live feed based, was also tested. Trials were performed with larvae from 1 to 25 days after hatching (DAH). Microencapsulated diets were introduced at 8 DAH in co-feeding with live feed and at 15 DAH larvae were fed the microencapsulated diets alone. Results showed a higher survival for the control group (8.6 ± 1.3% versus 4.2 ± 0.6% and 3.2 ± 1.8%) although dry weight and growth were similar in all treatments. The proportion of deformed larvae as well as the ammonia excretion was lower in the group fed a balanced diet than in the unbalanced or control groups (38.3% deformed larvae in control, 30% in larvae fed unbalanced diet and 20% on balanced diet group). Furthermore, larvae fed the microencapsulated diets presented higher docosahexaenoic acid and arachidonic acid levels. This study demonstrates that dietary amino acid profile may play an important role in larval quality. It also shows that balanced microencapsulated diets may improve some of the performance criteria, such as skeletal deformities, compared to live feeds. [source]


Development of deformities at the vertebral column in Diplodus sargus (L., 1758) early larval stages

AQUACULTURE RESEARCH, Issue 7 2010
Margarida Saavedra
Abstract One of the bottleneck problems of Diplodus sargus farming is a high incidence of skeletal deformities at the vertebral column. In this study, the pattern of vertebral deformities were determined in three different larval batches from 2 to 30 days after hatching (DAH). During this period, 60 larvae per spawn were observed at 2, 8, 13, 15, 18, 21, 23, 25, 27 and 30 DAH and the different types and frequency of vertebral column malformations were registered. Deformities started from 8 to 13 DAH, when the percentage of deformed larvae rose from approximately 5% to 40%. At 15 DAH, skeletal malformations had frequencies up to 80% of the observed larvae. Serious malformations such as kyphosis, scoliosis and lordosis were observed at 18 DAH but seldom in percentages higher than 15%. Vertebral fusions and compressions especially affected the preurostyle region. Abnormal shape vertebrae were more frequent between vertebrae 15 and 21. Other malformations observed were hypertrophic vertebrae, more common in the trunk and caudal regions, reaching percentages higher than 50% in the former. This study has useful information concerning skeletal malformations at the vertebral column of D. sargus larvae, as it identifies the main deformities observed and the ages of highest incidence. [source]


Vertebral deformity in cultured Atlantic cod larvae: ontogeny and effects on mortality

AQUACULTURE RESEARCH, Issue 14 2009
Velmurugu Puvanendran
Abstract The effects of different egg incubation densities on the incidences of vertebral deformities in Atlantic cod larvae were investigated. Cod eggs were incubated at four different densities, 3, 6, 12 and 48 mL eggs L,1, of water. When all the eggs hatched, larvae were reared in 30 L glass aquaria. Larval samples were taken at 0, 14, 42 and 56 days post hatch (dph) for deformity analysis. Larval samples were stained using bone and cartilage staining methods to determine vertebral deformity. Incubation densities did not have any significant effects on vertebral deformities in Atlantic cod larvae. However, the incidence of larval vertebral deformity was high at hatch and decreased as the larvae grew older until 42 dph, indicating selective mortality of deformed larvae during this period. Larvae at 56 dph, however, showed an increase in the incidence of vertebral deformity, indicating a possible nutritional or prey-type effect. To our knowledge, no studies have documented the occurrence of variable patterns in vertebral deformities in cod at various developmental stages. Overall, our results suggest that broodstock husbandry, genetics and/or nutrition could play a major role in causing vertebral deformities in Atlantic cod at hatch; however, nutrition and prey type may play a major role during metamorphosis. [source]