ABAH BI OFLUX
is bet ween 600 t o 800 µm and if t his is assum ed t o be so in aquafeeds, t hen m ore t han half of t he m illed Rhizoclonium m eal in t he present st udy w ould be less t han ideal. Furt her reduct ion in size could be done by put t ing back t o t he m ill t hose t hat did not pass t he 710 µm siev e size. The ideal size seem ed t o be t hose t hat are ret ained on 710 µm siev e size (i. e. t he m edium - sized part icles show n in Figure 3) w it h a GMD of 0. 65 µm and a GSD 1. 54 ( Table 2) ; t he lat t er index indicat es t he size v ariabilit y . This signified t hat m ost of part icles of t he Rhizoclonium grind w ere in t he sizes close t o t heir m edian size (i. e. GMD) and t hat t he uniform it y of part icle size w as good; also it s frequency of dist ribut ion alm ost follow ed a norm al dist ribut ion curv e. The fine- sized part icle in t he m odified m eal ( Figure 4) show ed t hat 80% of t he part icles w ere at 0. 15 m m , v ery fine part icles t hat m ight cont ribut e t o t he undesirable fines in t he final pellet product .
Figure 1. Part icle size dist ribut ion in unm odified Rhizoclonium m eal.
Figure 3. Part icle size dist ribut ion in m edium - sized Rhizoclonium m eal.
Figure 4. Part icle size dist ribut ion in fine- sized Rhizoclonium m eal.
There w ere part icle size ( PS) effect s on t he phy sical charact erist ics of t he Rhizoclonium
m eal as show n in Table 1. The im plicat ion of t his effect is t hat part icle size could det erm ine t he phy sical charact erist ics of a feed raw m at erial used in form ulat ing a feed regardless of it s prox im at e v alues. The final feed form ulat ed w it h t he sam e feed raw m at erial m ay yield different phy sical charact erist ics because of v ariat ions in PS lev els being used. The seaweed m eal ex hibit ed higher bulk densit y ( BD) at t he unm odified and at coarse PS t han at t he m edium and fine PS. This indicat es t hat even t hough t he crude fiber of t he m at erials m ay rem ain t he sam e, t heir densit ies could be m anipulat ed t o suit t he desire of t he feed form ulat or, wit h possible ult im at e effect s on t he perform ance of aquacult ure species. The relat ionship of t he PS (i.e. GMD) and BD is reflect ed in Table 3 show ing a v ery high correlat ion ( Pearson’s r= 0. 95) bet w een t he t w o phy sical indices.
Rhizoclonium m eal w as v ery m ark ed as reflect ed in Table 2 w here t he Pearson’s r w as Pearson product - m om ent correlat ion coefficient of t he biophy sical charact erist ics
dist ribut ion curv e. There w ere PS effect s on t he phy sical charact erist ics of t he
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Received: 09 Apr il 2015. Accept ed: 29 May 2 015. Published on line: 07 June 2 015. Aut hor s:
Mar j Gem Belgica Bunda, Univer sit y of t he Philipppines Visayas, College of Fisher ies and Ocean Sciences, I nst it ut e of Aquacult ur e, Philippines, Miagao, I loilo 50 23, e- m ail: m er ope012@gm ail. com
Bar r y Leonar d Malt o Tum bokon, Univer sit y of t he Philippines Visayas, Nat ional I nst it ut e of Molecular Biology and Biot echnology, Philippines, Miagao, I loilo 50 23, e- m ail: bt um bokon@gm ail. com
August o Er um Ser r ano Jr . , Univer sit y of t he Philippines Visayas, Nat ional I nst it ut e of Molecular Biology and Biot echnology, Philippines, Miagao, I loilo 5 02 3, e- m ail: ser r ano. gus@gm ail. com
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