Effects of dietary cottonseed meal protein levels on growth and feed utilization of Nile &lt;i&gt;tilapia, Oreochromis niloticus L&lt;/i&gt;

Nw Agbo,N Madalla,K Jauncey

doi:10.4314/jasem.v15i2.68495

Abstract

The nutritional suitability and cost effectiveness of cottonseed meal (CSM) as protein source in the diet of Nile tilapia (Oreochromis niloticus L.) with mean initial weight 4.24±0.20 g, was evaluated over a 56-day growth period. Four isonitrogenous (320 g kg-1), isolipidic (100 g kg-1) and isoenergetic (18 KJ g-1) test diets were formulated in which CSM protein replaced fish meal (FM) protein at levels of 0% (control), 25%, 50% and 75%. The control diet had FM as the sole protein source. The growth experiment was conducted in plastic tanks in a recirculation system each dietary treatment was in triplicate. After 56 days of feeding fish at 6% - 4% body weight per day, CSM protein replacements of 25% and 50% did not significantly (P

Highlights

With the increase in intensive aquaculture, demand for more efficient dry diets for fish is rising
In recent years intensification of Nile tilapia, Oreochromis niloticus production in Ghana and expansion of aquaculture has generated the need for development of suitable feeds
The use of fish meal at high levels in fish feeds is not feasible in Ghana because of its high price and limited supply, in contrast there is a large number of oilseed and cereal by-products available, a good example being cottonseed meal (CSM), which is cheap and readily available

Summary

MATERIALS AND METHODS

Fish were reared in plastic tanks (30 L) in a recirculation system which was supplied with aerated water at a flow rate of 1 L min-1 with temperature maintained at 27 ± 1oC. Diet formulation and preparation: Cottonseed meal (crude protein, 441.4 g kg-1) used in this study was obtained from commercial sources in Ghana fish meal (crude protein, 716.3 g kg-1) and wheat grain (crude protein, 95.2 g kg-1) were supplied by Ewos Ltd (Bathgate, UK). Four isonitrogenous (320 g kg-1 protein), isolipidic (100 g kg-1 lipid) and isoenergetic (18 KJ g-1) diets were formulated for this experiment (Table 1) to satisfy the nutrient requirements of Nile tilapia (NRC, 1993). The control diet was formulated with fish meal as the sole source of protein and this was replaced at different levels with CSM protein at inclusion levels of 25%, 50% and 75% (designated as CSM25, CSM50 and CSM75). Feeding rates were adjusted every week and the experiment lasted eight weeks (56 days)

Corn starch

RESULTS AND DISCUSSIONS

Trypsin inhibitors

Profit index