ABSTRACT
This study was conducted to elucidate the impact on the growth and feed availability of rockfish (Sebastes schlegeli) from including jack mackerel meal (JMM) in feeds which otherwise substitute 20% fish meal (FM) with chicken by-product meal (CBM). Six formulated feeds were designed to be isonitrogenous and isolipidic. Specifically, 55% FM was included in the control (Con) diet. In the Con diet, 20% FM was substituted by CBM, and then the graded levels (0, 20, 40, 60, and 80%) of JMM were included instead of FM, named as the C20J0, C20J20, C20J40, C20J60, and C20J80 diets, respectively. Five hundred and forty juvenile rockfish (initial weight of 11.2 g) were assigned to 18 tanks. All experimental feeds were fed to triplicate groups of rockfish twice daily for 8 weeks. Superior weight gain, specific growth rate (SGR), and feed intake of rockfish fed the C20J60 and C20J80 diets compared to rockfish fed the Con and C20J0 diets were observed. However, the feed utilization, biological indices, proximate composition, amino acid profiles, and blood chemistry of the rockfish were not affected by the dietary treatments. The slightly but not significantly higher economic profit index and growth performance were obtained in the C20J60 diet compared to the C20J80 diet. In conclusion, the C20J60 diet was the most recommendable treatment based on the improvement in growth performance (weight gain and SGR) and feed intake of rockfish, and the highest economic return to farmers.
ABSTRACT
This experiment was performed to assess the substitution impact of fish meal (FM) with tuna by-product meal (TBM) in feeds on growth and feed availability of the early stage of juvenile rockfish (S. schlegeli). Six experimental feeds were prepared to be isonitrogenous and isolipidic. Fifty-five percent of FM was contained in the control (Con) diet. In the Con diet, 20, 40, 60, 80, and 100% FM were replaced by TBM, named the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. A total of 540 early-stage juvenile rockfish averaging 2.4 g was divided into 18 tanks and hand-fed to satiation for 56 days. Weight gain and feed consumption of rockfish fed the TBM20 and TBM40 diets were comparable to rockfish fed the Con diet. The specific growth rate (SGR) of rockfish fed the Con diet was comparable to rockfish fed the TBM20, TBM40, and TBM60 diets. Feed efficiency, biometric indices, hematological parameters, proximate composition, and amino acid profiles of rockfish were not impacted by dietary treatments. The economic profit index (EPI) of the Con, TBM20, and TBM40 diets were higher than that of all other diets. FM up to 40% could be substitutable with TBM in the diets of rockfish without deteriorating weight gain and feed consumption, but producing the highest EPI.
ABSTRACT
Dietary inclusion effect of feed ingredients showing high feeding attractiveness to rockfish on the growth, feed utilization, condition factor (CF) and whole body composition of fish was investigated. Three hundred sixty juvenile rockfish were randomly distributed into 18 50-L flow-through tanks (twenty fish per tank). Six experimental diets were prepared: the control (Con) diet containing 55% anchovy meal, and 5% anchovy meal in the Con diet was replaced with an equivalent amount of jack mackerel, sardine, Pollack, squid and shrimp meals, referred to as the JM, SM, PM, SQM and SHM diets, respectively. Each diet was assigned in triplicate and hand-fed to satiation twice daily for 8â¯weeks. Weight gain (20.7⯱â¯0.03), amount of feed supply (20.1⯱â¯0.05) and CF (1.50⯱â¯0.002) of rockfish fed the JM diet were greater than those of fish fed all other diets, followed by the SM (20.3⯱â¯0.04, 19.5⯱â¯0.08 and 1.48⯱â¯0.003), PM (19.9⯱â¯0.09, 19.2⯱â¯0.05 and 1.47⯱â¯0.003), SQM (19.5⯱â¯0.06, 18.8⯱â¯0.07 and 1.45⯱â¯0.002), SHM (19.0⯱â¯0.12, 18.3⯱â¯0.09 and 1.44⯱â¯0.001) and Con diets (17.8⯱â¯0.07, 17.2⯱â¯0.05 and 1.43⯱â¯0.005). However, feed efficiency, protein efficiency ratio and protein retention was not affected by the experimental diets. The proximate composition of the whole body of fish, except for ash content was not affected by the experimental diets. In conclusion, the greatest weight gain, amount of feed supply and CF of rockfish were obtained in the JM diet, followed by the SM, PM, SQM, SHM and Con diets, in order.
Subject(s)
Animal Feed/analysis , Body Composition , Feeding Behavior , Perciformes/physiology , Animals , Diet , Perciformes/growth & developmentABSTRACT
The cDNA nucleotide sequence of genome segment B encoding the VP1 protein was determined for the aquatic birnavirus GC1 isolated from the rockfish Sebastes schlegeli in Korea. The VP1 protein of GC1 contains a 2,538 bp open reading frame, which encodes a protein comprising 846 amino acid residues that has a predicted MW of 94 kDa. The sequence contains 6 potential Asn-X-Ser/Thr motifs. Eight potential Ser phosphorylation sites and 1 potential Tyr phophorylation site were also identified. GC1 contains the Leu-Lys-Asn (LKN) motif instead of the typical Gly-Asp- Asp (GDD) motif found in other aquatic birnaviruses. We also identified the GLPYIGKT motif, the putative GTPbinding site at amino acid position 248. In total, the VP1 regions of 22 birnavirus strains were compared for analyzing the genetic relationship among the family Birnaviridae. Based on the deduced amino acid sequences, GC1 was observed to be more closely related to the infectious pancreatic necrosis virus (IPNV) from the USA, Japan, and Korea than the IPNV from Europe. Further, aquatic birnaviruses containing GC1 and IPNV have genogroups that are distinct from those in the genus Avibirnaviruses and Entomo-birnaviruses. The birnavirusstrains were clustered into 5 genogroups based on their amino acid sequences. The marine aquatic birnaviruses (MABVs) containing GC1 were included in the MABV genogroup; the IPNV strains isolated from Korea, Japan, and the USA were included in genogroup 1 and the IPNV strains isolated primarily from Europe were included in genogroup 2. Avibirnaviruses and entomobirnaviruses were included in genogroup 3 and 4, respectively.
Subject(s)
Animals , Amino Acid Sequence , Base Sequence , Birnaviridae/classification , Capsid Proteins/chemistry , Cell Line , Fishes/virology , Korea , Molecular Sequence Data , PhylogenyABSTRACT
Black rockfish (Sebastes schlegeli) is an important mariculture species in Korea. The production of this fish is drastically declined due to bacterial diseases, particularly streptococcosis caused by Lactococcus garvieae. The bacterial surface characteristics of SJ7 and TY6 were found to have capsule but not NB13 and YS18. The experiential evaluation of L. garvieae pathogenicity, the capsular isolates showed high cumulative mortality i.e. SJ7 (100%) and TY6 (60%) compared to non-capsular isolates. Based on this result the capsular isolates L. garvieae were highly suspected as the causative agent of streptococcosis in rockfish.
