Effect of dietary cobalt supplementation on the population growth of rotifer Brachionus rotundiformis

Abstract

KEY WORDS: Chlorella, cobalt, culture, rotifer, vitamin B 12 .All forms of animals require inorganic elements or minerals for their normal and healthy life processes. Therefore, many minerals play an important role in animal nutrition, including aquatic animals like fish. 1 Cobalt (Co) is known as a constituent mineral of vitamin B 12 (VB 12 ), having cyanocobalamin (C 63 H 88 CoN 14 O 14 P) as a representative compound. VB 12 is a type of water soluble vitamin, which is essential for maintaining normal and healthy physiological conditions for both terrestrial and aquatic animals. VB 12 can be manufactured only by microorganisms like gut bacteria, and natural sources are entirely of animal origin. Therefore, it is a common technique for fish farmers to add Co compounds as a material for synthesizing VB 12 in the gut and enhance the dietary value of the fish feed by satisfying their VB 12 requirement. 1-3 In zooplankton, the function of VB 12 for promoting growth performance was previously investigated in rotifer. 4-7 However, no study has been conducted so far on the supplemental effect of Co for zooplanktons including rotifer, despite its importance in aquaculture. In this paper, the authors preliminarily investigated the supplemental effect of Co compound into rotifer feed for enhancing its production performance.Marine rotifer Brachionus rotundiformis (mean lorica length ± standard deviation [SD] of matured individual: 192.5 ± 13.8 µm) was used for the experiment. The stock-cultured rotifer was inoculated into triplicated 850 mL glass bottles (working volume: 800 mL) at densities of 240 ind/mL. The rotifer was cultured under natural photoperiod at 30°C with ordinary aeration in full seawater condition (salinity 33 psu). As rotifer feed, VB 12 -free Chlorella vulgaris cultured in the laboratory using 5 L jar-fermentors were supplied. The cultured Chlorella was centrifuged to the concentration of 10 10 algal cells/ mL and stored at 5°C until used for the experiment. The Chlorella concentrate was fed once a day in the morning at a ratio of 50 000 algal cells/rotifer per day, based upon the optimum feeding ratio reported in previous papers. [8][9][10][11] The VB 12 contents of VB 12 -free Chlorella and sea water used for the experiment were confirmed to be 0.0 pg/mL by bioassay using Lactobacillus delbrueckii. 2 The supplemental effect of dietary Co compound was investigated as follows. As the Co source, cobalt (II) sulfate heptahydrate: CoSO 4 ·7H 2 O was used. The concentration of dietary Co compound was decided from a preliminary experimental result: 4-day-batch trial with duplicate treatment, 238.3, 939.8 and 582.1 ind/mL were obtained as the mean final densities of the rotifers from 250 ind/mL inoculum for 0, 0.01 and 1.0 mg/mL Co supplemented feed groups, respectively (unpubl. data, T Higuchi 2002). Co compound was dissolved into distilled water and mixed into Chlorella concentrate to establish the dietary concentrations of 0, 0.001, 0.01 and 0.1 mg/mL, and fed to the rotifers. Also, acute toxicity of the co...

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“…However, Vibrio concentration increased when rotifer fed 75% Beaker's yeast substituted diet. These results could be related to vitamin B 12 and protein content of Saccharomyces cerevisiae as previously reported in other studies (Lubzens, Tandler, & Minkoff, 1989;Ferreira, Pinho, Vieira, & Tavarela, 2010 (Yoshimatsu, Higuchi, Zhang, Fortes, Tanaka, & Yoshimura, 2006). Fatty acid composition of rotifer and artemia were improved by enrichment products in our study.…”

Preliminary Trials on the Effect of Lighting for the Population Growth of the Rotifer, Brachionus plicatilis

“…Recently we reported the dietary supplementation of a water-soluble cobalt compound (cobalt (II) sulfate heptahydrate: CoSO 4 7H 2 O) also effectively enhanced the population growth of the S-type rotifer B. rotundiformis 23 . Cobalt (II) sulfate heptahydrate is a cheap compound easy to obtain in the market and used as a common and safe trace mineral food additive for many livestock and cultured fish in many countries 7 .…”

“…The concentration of cobalt compound was decided based on a previous experimental result: i.e. 0.1 mg/L culture water/day 23 . Cobalt compound was dissolved into freshwater in advance and trickled into culture water when feed was given in the morning.…”

“…In aquaculture relevancy, the function of VB 12 for enhancing population growth performance of rotifers was studied and reported previously 8,17,30,31 . Recently we found a cobalt compound (cobalt (II) sulfate heptahydrate: CoSO 4 7H 2 O) supplementation to rotifer feed also effectively enhanced the population growth of the S-type rotifer B. rotundiformis 23 . We also experienced lately that lighting of the rotifer culture tank practically stabilized the culture and improved its production performance.…”

Influence of Temperature and Salinity on the Growth and Size of the Rotifer Brachionus plicatilis and B. rotundiformis

“…plicatilis 250-300 µm large-type B. rotundiformis 160-220 µm small-type 100-140 µm ultra smalltype strain , , , (Minkoff et al, 1983, Yoseda et al, 2003. rotifer (Lubzens andMinkoff, 1988, Stelzer, 2002) ( Snell et al, 1983, Park and Hur, 1996a, Yoshimatsu et al, 2006 25-27 (Lubzens and Minkoff, 1988, Cabrera et al, 1993, Kobayashi et al, 2009), 4-35 psu strain (Walker, 1981, Park and Hur, 1996b, Tomoda et al, 2011. Pascual and Yúfera (1983) …”