Experimental shrimp diet with low levels of vegetable protein and lipids produced acceptable results
Most aquafeed manufacturers use expensive squid meal, fishmeal, and marine fish oils to meet protein requirements in their products. However, recent research has shown that vegetable and terrestrial animal proteins and oils could be used to successfully replace marine proteins and oils in feeds for many aquatic species, including penaeid shrimp.
In late 2001, the authors conducted a 69-day grow-out trial in outdoor ponds at the OceanBoy Farms facility in Labelle, Florida, USA to compare the performance of various aquafeeds. OceanBoy is engaged in applied research to increase protein levels from vegetable sources in its shrimp feeds.
The diets were tested at varying stocking densities, ranging 33 to 138 shrimp per square meter. Animals used in the study were first reared for 21 days in a greenhouse nursery system and then moved to 12 outdoor, 1-ha, plastic-lined ponds with strong aeration and zero water exchange.
Dissolved oxygen, pH, salinity, and temperature were monitored twice daily. Ammonia, nitrite, and nitrate levels were monitored weekly. All water-quality parameters measured remained within acceptable levels.
Four diets were used in the study. Table 1 shows proximate analyses of the feeds described below.
- Diet 1: Experimental OceanBoy formulation with low levels of vegetable protein and lipids, and standard vitamin and enzyme input.
- Diet 2: Feed with lipids of vegetable origin and protein from vegetable and marine sources (OceanBoy formulation).
- Diet 3: Formulation provided by Dr. Allen Davis of Auburn University in Auburn, Alabama, USA with poultry meal instead of fishmeal and fish oil for palatability.
- Diet 4: Formulated by Robins McIntosh (formerly with Belize Aquaculture Ltd.), this diet contained medium levels of marine proteins and oils.
McMahon, Proximate analysis of selected feeds, Table 1
Table 2 summarizes survival, growth, feed conversion and stocking density after 69 days of culture. As shown in the table, diet 4 produced the highest mean final weight (10.40 grams), followed by 6.97 grams for diet 3, 6.23 grams for diet 2, and 5.40 grams for diet 1. Diets 3 and 4 produced survival results of about 87 percent, closely followed by diet 2 and then diet 1 at 73 percent. The lowest feed conversion ratio (1.17) was obtained with diet 2.
McMahon, Summary of survival, growth, feed conversion, Table 2
The study of feed performance showed that an experimental diet with low levels of vegetable protein and lipids, although ranking last in growth and survival among the diets tested, still produced acceptable results. Feed protein requirements can effectively be reduced and vegetable protein sources increased in shrimp feeds.
(Editor’s Note: This article was originally published in the April 2002 print edition of the Global Aquaculture Advocate.)
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