Proximate composition and dry matter digestibility of Ulva lactuca in the black tiger shrimp Penaeus monodon

Proximate composition of both the raw dried powder and protein concentrate of Ulva lactuca in in vivo assays of apparent digestibility of dry matter (ADMD) and apparent digestibility of ingredient (ADI) was conducted to measure the bioavailability of raw Ulva powder (URDP) and Ulva protein concentrate (UPC) as a feed ingredient in the diet of the black tiger shrimp Penaeus monodon. UPC contained almost three times more crude protein than RDUP but contained more than half of the ash content. Crude fat, moisture and NFE differed only slightly between the two Ulva forms. The major biochemical component in both UPC and RDUP was nitrogen-free extract assumed to be digestible carbohydrates. The ADMD of the test diet containing UPC was significantly higher (98.76 %) than that of the RDUP (71.53 %) while the ADI of UPC was significantly higher (99.13 %) than that of the RDUP (71.17 %). ADI is one of the good indicators of the quality of feed ingredients and can be used to select ingredients for shrimp feeds. P. monodon appeared to have the capacity to effectively digest Ulva lactuca in either raw dried powdered form or a powder protein concentrate as ingredients that might have very different nutritional qualities, which may reflect the natural preference and omnivorous generalist-type feeding behavior of this shrimp. The information obtained in this study will aid in the formulation of cost-effective diets for the black tiger shrimps.