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ผู้เขียน หัวข้อ: United States; Texas--Texas A&M--Molasses as a Carbon Source  (อ่าน 2704 ครั้ง)
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« เมื่อ: เมษายน 12, 2007, 09:43:48 PM »



Two studies were conducted using the Pacific white shrimp Penaeus vannamei to evaluate the effect of carbon supplementation on selected water quality indicators and shrimp performance in the nursery and the growout phases using limited water discharge with molasses as a carbon addition.

A preliminary nursery study was conducted in four 40 m3 greenhouse-enclosed raceways stocked with 12-day-old postlarvae at a density of 1,800 m3 and were fed 45% crude protein feed. Molasses (24% carbon) was used for carbon supplementation to provide 6 grams of carbon for each 19 grams of total ammonia nitrogen (TAN) in the water and started 32 days after stocking, shortly after the TAN level had risen to over 3 milligrams per liter. The data suggest that molasses addition resulted in rapid reduction of TAN and nitrite nitrogen and could be used to prevent buildup of these compounds.

The growout study was carried out using twenty 7.8 m3 tanks stocked with juvenile shrimp at a density of 81 m3. Shrimp were fed a commercial diet (30% crude protein, Rangen, Inc., Buhl, Idaho, USA). Feed rations were determined based on assumed growth of one a gram week, a feed conversion ratio of 1.5 and a weekly mortality rate of 0.5%. Molasses additions, at five levels, were started 26 days post stocking to provide 0%, 50%, 100% and 150% of the theoretical carbon level needed for bacteria to assimilate the TAN from the feed. The fifth treatment was based on the actual level of TAN in the tanks and was adjusted daily on an as needed basis. The data suggest that under the condition of this study, addition of molasses did not result in a significant effect on water quality or on shrimp performance.

The present work was aimed only at the effect of molasses addition to low protein diets (30%). Molasses was added only as means to reduce TAN and nitrite nitrogen and not as feed replacement. Based on final growth indicators additional molasses had no effect on the shrimp under the condition of this study.

This study demonstrated that molasses could be used as a tool to prevent increases in TAN and nitrite during the nursery and growout phases of the Pacific white shrimp, Penaeus vannamei, under limited water discharge. There was no significant difference due to molasses addition on shrimp performance in the nursery phase. Similarly, no significant effect was observed for water quality or shrimp performance in the growout phase when the shrimp were fed a low protein diet under limited water discharge when culture water was supplemented with various levels of molasses.

Source: Aquaculture Engineering. Use of molasses as carbon source in limited discharge nursery and growout systems for Litopenaeus vannamei. Tzachi M. Samocha (Texas Agricultural Experiment Station, Shrimp Mariculture Research Facility, 4301 Waldron Road, Corpus Christi, TX 78418 USA), Susmita Patnaik, Mike Speed, Abdul-Mehdi Au, Josh M. Burger, Rodrigo V. Almeida, Zarrein Ayub, Margasanto Harisanto, Ami Horowitz and David L. Brock, Volume 36, Issue 2, Page 184, March 2007.
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