Abstract
Four experiments were conducted to develop cost-effective feed for freshwater prawn (Macrobrachium rosenbergii) and Nile tilapia (Oreochromis niloticus) by inclusion of sunflower cake (SFC), substituting expensive fish meal and conventional plant protein sources like soybean meal and mustard oilcake. Experiment-I was conducted to test the effectiveness of SFC for freshwater prawn feed. Four isonitrogenous (~30% crude protein) and iso-caloric (388 - 402 kcal) diets were formulated. Diet-1 as control was formulated with conventional protein sources; Diet-2, Diet-3 and Diet-4 were formulated by inclusion of 30, 40 and 50% SFC respectively, substituting fishmeal and plant proteins used in Diet-1. After 100 days, all diets containing SFC (30-50% inclusion) showed better growth, carcass quality and economic performances trend compared to control diet-1 (P>0.05). Higher mean production (572.89 ± 62.99 kg/ha) with Diet-4 containing 50% SFC, demonstrated best FCR (2.56 ± 0.24), SGR (1.18 ± 0.05) and PER (1.14 ± 0.10) values. Highest income, gross margin and benefit cost ratio (BCR) per hectare from prawn were US$ 5,759, US$ 2,623 and 1.84 respectively achieved with Diet-4, which was also the cheapest among four diets. In experiment-II, Diet containing 50% SFC (Diet-3) was tested against two commercial feeds (Diet-1 and Diet-2) and nonsignificant (P>0.05) growth, carcass quality and economic performances were observed. Higher production (563.33 ± 39.50 kg/ha) was achieved with Diet-3, followed by Diet-1 and Diet-2. Diet-1 displayed better FCR (2.18 ± 0.10) followed by Diet-3 (2.28 ± 0.18); Diet-3 achieved better SGR (1.18 ± 0.03) and PER (1.31 ± 0.10) compared to other diets. Highest income, gross margin and BCR per hectare from prawn US$ 6,139, US$ 2,995 and 1.84 respectively were found in Diet-3. Experiment-II suggests that the feed containing SFC up to 50% can be equally efficient like any commercial feeds. Overall, feed with 50% SFC inclusion appeared to be most cost-effective diet for prawn with no statistically significant differences in growth, flesh quality or economics. In experiment-III, four isonitrogenous (~26% crude protein) and isocaloric (354 - 376 kcal) diets were formulated for Nile tilapia. Among the diets, Diet-1 referred as control; Diet-2, Diet-3 and Diet-4 containing 30, 40 and 50% SFC respectively and 15% yellow maize inclusion, where fishmeal, soybean meal and mustard oilcake used in Diet-1 were partially replaced. After 100 days, all diets with SFC inclusion showed better growth, carcass quality and economic performances compared to control diet (P>0.05). Better production (4,437.55 ± 62 kg/ha) with Diet-3, followed by Diet-2, Diet-4 and Diet-1. Diet-3 demonstrated better FCR (1.37 ± 0.05), SGR (1.04 ± 0.01) and PER (2.25 ± 0.08). Highest income, gross margin and BCR per hectare from tilapia were US$ 6,258, US$ 2,332 and 1.59 respectively achieved with Diet-3. Diet-3 containing 40% SFC appeared to be most cost-effective, which suggests strong potential of SFC as substitute for conventional protein sources in tilapia feed. In experiment-IV, Diet-3 containing 40% SFC inclusion was tested with two commercial feeds (Diet-1 and Diet-2) demonstrated no significant difference (p>0.05) of growth, carcass quality and economic performances but cheapest Diet-3 achieved better gross margin. Highest production (6,234.31 ± 465.76 kg/ha) was achieved with Diet-1 followed by Diet-3 (6,044.55 ± 257.25 kg/ha) and Diet-2. Tilapia fed with Diet-1 displayed better FCR (1.41 0.09) and SGR (1.55 ± 0.03) followed by Diet-3 (1.42 ± 0.06) and (1.54 ± 0.02) respectively. Diet-1 demonstrated highest total income US$ 8,792/ha, however, highest gross margin US$ 2,881/ha and BCR 1.51 were achieved with the cheapest Diet-3. The results suggested that, tilapia feed formulated using SFC inclusion up to 40% or possibly more could be cost-effective and comparable to any commercial feeds. The experiments suggest that sunflower cake could be substituted against fishmeal and other plant proteins without negative consequences in performance, but potentially producing cost savings and a sustainable alternative. All feeds containing sunflower cake demonstrated reduced cost of production for prawn by 8.58% to 27.15% and for tilapia 20.79% to 32.38% compared to feeds without SFC. Further research is needed to investigate effectiveness of higher SFC concentrations and optimal balance of those ingredients.