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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #169700
Title: PLASMA STEROID, CATHPSIN ACTIVITY AND EGG SIZE AND PROTEIN CONTENT DURING IN VIVO OOCYTE MATURATION IN FOUR STRAINS OF CHANNEL CATFISH BROODSTOCK

Author
item BARRERO, M - MISS. STATE UNIV.
item Small, Brian
item D'ABRAMO, L - MISS. STATE UNIV.
item KELLY, A - UNIV. OF S. ILLINOIS
item HANSON, L - MISS. STATE UNIV.

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/4/2004
Publication Date: 1/20/2005
Citation: Barrero, M., Small, B.C., D'Abramo, L.R., Kelly, A.M., Hanson, L.A. 2005. Plasma steroid, cathpsin activity and egg size and protein content during in vivo oocyte maturation in four strains of channel catfish broodstock. Proc. Aquaculture America 2005. p. 23.

Interpretive Summary:

Technical Abstract: The US catfish industry is beset by inefficiency, founded upon the low spawning success of female broodstock for the annual production of fingerlings. Current estimates of spawning success of females range from 20-30%. An understanding of the relationship of annual changes in physiological indices during a reproductive cycle to oocyte maturation and successful spawning in channel catfish (Ictalurus punctatus) may contribute to an accurate prediction of successful spawns. The objective of this study was to evaluate the effects of plasma steriod concentrations (estradiol and testosterone), egg size and protein degredation by cathepsins D, L and B on in vivo egg maturation in four strains of channel catfish. Groups of nine, 2-year old female channel catfish broodstock obtained from each of 4 different strains (NWAC103, D, C, and T) were tagged and stocked into four 0.04 ha earthen ponds (36 fish per pond, 9 fish per strain) in April. Blood and egg samples were collected from twelve fish in each pond (3 fish/strain) every month for 11 and 9 months, respectively, thereafter. No individual fish within a strain was subject to sampling more than once every four months. For all strains, mean plasma estradiol concentrations ranged from 0.02 to 0.29 ng/mL from June through December, and increased dramatically in January, peaking in February (3.4 to 3.7 ng/ml), and remained above 1.00 ng/mL through May. Mean plasma testosterone concentrations increased from May through September (0.03 to 1.23 ng/mL), decreased in October, and then increased and remained at approximately 1 ng/mL through April. Mean activities of cathepsins D and L steadily increased beginning in October and were highest in March, whereas the activity of cathepsin B was variable from month to month. Mean protein content of eggs was highest in October (3.08 to 3.795) when eggs appeared and decreased to levels of 0.54 to 2.14% for the remainder of the year (November through April) when eggs were present. From October to November the mean egg size increased by approximately 40%, to 1.0 - 1.4 mm, and remained at this size until May and June when size increased by approximately 75 - 100%. No noteworthy differences in the mean values of the physiological indices monitored were observed among the four strains during each month. This information should serve as a foundation to apply in the evaluation of the relative effectiveness of exogenous hormone treatments in increasing the spawning success of channel catfish and the channel catfish x blue catfish hybrid.