Growth and feed utilization in two strains of gibel carp, Carassius auratus gibelio: paternal effects in a gynogenetic fish

Gibel carp (Carassius auratus gibelio Bloch) is a natural gynogenetic fish which requires sperm of the same or related species to activate egg develop ment. The eggs of one gibel carp were divided into two batches. One batch w as 'fertilized' with sperm from gibel carp (strain DD), and the other 'fert ilized' with sperm from red common carp (Cyprinus carpio red variety) (stra in DR). The juveniles were transferred to the laboratory 36 days post-hatch . Triplicate groups of each strain were fed a formulated diet at either 3% or satiation ration for 8 weeks. At both the restricted and satiation ratio ns, specific growth rate was significantly higher in strain DR than in stra in DD. At the 3% ration, there was no significant difference in feeding rat e or feed conversion efficiency between the two strains. At the satiation r ation, strain DR had a significantly lower feeding rate but higher feed con version efficiency than strain DD. At the satiation ration, strain DR had a significantly lower intake protein, but higher recovered protein than stra in DD. There was no significant difference in faecal protein loss between t he two strains. At the 3% ration, strain had no significant effects on inta ke protein, faecal protein or recovered protein. Neither faecal energy loss nor recovered energy was affected by strain or ration. At both the 3% and satiation ration, final body contents of dry matter and lipid were signific antly lower in strain DR than strain DD, while there was no significant dif ference in protein and energy content between the two strains at either rat ion level. The results suggested that gibel carp 'fertilized' with sperm of common carp grew faster than those 'fertilized' with sperm of gibel carp t hrough increased feed conversion efficiency and protein retention.