Effects of processed duckweed (Lemna paucicostata) meals as protein sources in Oreochromis niloticus (Linnaeus, 1758) diets

Abstract

Effects of processed duckweed meals as a replacement for toasted soybean meal in the diets of Oreochromis niloticus fingerlings were evaluated. Sun-dried and blanched duckweed meals were used to replaced toasted soybean meal in at 25, 50, 75, and 100% each. Feed Solution Software (version 2022) was used to formulate nine iso-nitrogenous diets at 32% crude protein. 27 Hapa nets of 1 m2 each were used for the feeding trials for six months. Ten fingerlings of Oreochromis niloticus were stocked per Hapa and fed 5% body weight three times per day. The best mean weight gain (460.59 g), viscerosomatic index (9.90) and feed conversion ratio (1.82) were recorded in the fish fed 75% blanched duckweed meal while the fish fed 100% sun-dried duckweed meal and 100% blanched duckweed meal recorded the poor mean weight gain, viscerosomatic index and feed conversion ratio of 401.69 g and 394.03 g, 6.49 and 6.36, 2.06 and 2.10, respectively. The cost-benefit evaluation revealed that 75% blanched duckweed meal gave the highest net profit (₦3,682) and lowest incident cost (₦6.49). This study revealed that soybean meal can be replaced with 75% blanched duckweed meal in the diet of Oreochromis niloticus without any inauspicious effects on the growth and nutrient utilization, and will reduce the cost of production and maximize profit.