EFFECTS OF REPLACEMENT OF SOYA BEAN (GLYCINE MAX. LINN) MEAL WITH SOYA BEAN OFFAL MEAL IN THE DIET OF NILE TILAPIA OREOCHROMIS NILOTICUS (LINNAEUS, 1758) FINGERLINGS

The study was conducted to investigate the effect of replacing soya bean meal with soya bean offal meal in the diet of Nile tilapia O. niloticus fingerlings and to determine its growth performance. Fifteen (15) plastic rearing tanks (30cm x 45cm x 35cm depth) were used for the experiment. Plastic rearing tanks were randomly assigned in three replicates to five treatments. Three hundreds (300) fingerlings of O. niloticus of mixed sexes and sizes of initial mean weight of (6.0±2.04a g) were stocked in fifteen (15) white rectangular plastic tanks of water holding capacity of 50 litres (30cm x 45cm and 35cm depth) with twenty (20) fingerlings per tank and water maintained at 40 litres level for a period of twelve (12) weeks. Soya bean Offal meal (SBOFFM) was used to replace Soya bean meal (SBM) at inclusion levels of 0%, 25%, 50%, 75% and 100% for Diet 1 to 5 respectively. T1- 24.82±0.72b CP, T2- 25.34±1.93a CP, T3- 24.75±1.01b CP, T4- 24.21± 0.43b CP and T5- 25.12±0.70a CP. Total growing period was 97 days (14 days of acclimatization and 83 days of feeding). The results obtained showed T2 (25.34±1.93a) (25%) inclusion Soya bean Offal had the highest Mean Weight Gain (MWG) of (21.97±4.29a g), Mean Length Gain (MLG) of (1.76±0.23a cm), Protein Efficiency Ratio (PER) of 0.867±0.5a g, Net Protein Utilization (NPU) of 150.35± 0.2a %, Feed Efficiency Ratio (FER) of 1.89±0.4a, Gross Feed Conversion Efficiency (GFCE) of  200.00±0.4a   and crude protein of O. niltocus carcass (38.1±0.20a g/100g DM). Feed Conversion Ratio (FCR) and Specific Growth Rate showed no significant difference (P≥0.05). Also, pH (1-12), Temperature (T°C), Dissolved Oxygen (DO) (mg/l), Electrical Conductivity (µ/S), and Total Dissolve Solute (TDS) (mg/l) showed no significant difference (P ≥0.05). The study results demonstrate that soybean offal meal could replace the soya bean meal in the diet of Nile tilapia without negative effects on growth, or on total production and even leading to high net economic returns as shown in the diets with 25% CP crude protein from plant source.

 

 

 

Figure 4.1: Cost and quantity of Feed ingredients used in Formulating of diets for O.niloticus  51

 

Appendix VI : Lateral view of O.niloticus after the experiment     75

As aquaculture production becomes more and more intensive in Nigeria, fish feed could be a significant factor in increasing the productivity and profitability of aquaculture as it accounts for at least 60 percent of the cost of fish production (Jamiu and Ayinla, 2003).The need to intensify the culture of the fish, so as to meet the ever increasing demand for fish has made it essential to develop suitable diets either in supplementary forms for ponds or as complete feed in tanks (Olukunle, 2006). For the purpose of nutritional and economic benefits, previous researchers have made attempts at increasing the use of non-conventional plant and animal materials to replace conventional feed ingredients like maize and fish meal in fish feed ration. Nigeria is the second largest producer of farm-raised tilapia in Africa, after Egypt (Fagbenro et al., 2010), however, her contribution to global output is just a meager 28,950 metric tons. One of the greatest advantage of tilapia for aquaculture is that they feed on a low trophic level. The members of the genus Oreochromis are all herbivorous, feeding on algae, aquatic plants, and other, detrital material (Agbo et al., 2015).

Supplemental diets are usually much less expensive than complete diets and usually high in carbohydrates as well as increasing productivity (Abu et.al., 2010). Tilapia exhibit their best growth rates when they are fed a balanced diet that provides a proper mixture of protein, carbohydrates, lipids, vitamins, mineral and fibre. Krome et.al. (2016) provided excellent reviews that examined the details of tilapia nutrition. The nutritional requirements are slightly different for each species and more importantly vary with life stages. Fry and fingerlings require a diet higher in protein, lipids, vitamins and minerals and lower in carbohydrates as they are developing muscle, internal organs and bone with rapid growth. Sub-adult fish need more calories from fat and carbohydrates for basal metabolism and a smaller percentage of protein for growth. Adult fish need even less protein, however the amino acids that make up that protein need to be available (Agbo et al., 2015). Corn, wheat, rice and a number of agricultural products are typical carbohydrate sources (Agbo et al., 2015). The ratio of energy, lipids and carbohydrates to the proteins available in the diet are often critical measures. Ng and Romano (2013) provided a comprehensive review of carbohydrate and fiber utilization in tilapia. Vitamins and minerals are critical to proper nutrition in tilapia and considerable research has been conducted to determine these requirements (Agbo et al., 2015). Specific nutritional needs vary with species, age of fish, production system, and salinity. According to FAO (2006), fish supplies from capture fisheries will therefore, not be able to meet the growing global demand for aquatic food. There is need for a viable alternative fish production system that can sufficiently meet this demand, and aquaculture fits exactly into this role (Abu et al., 2010). Precocious breeding and high cost of feed are among the militating factors to tilapia production. Although, there has been breakthrough in checking the precocious breeding of tilapia through genetically modified parent stock and administration of Methyl-testosterone (MT) feed, availability of cost effective and highly potent feed still remains a major constraint to tilapia culture.

Fish feed account for about 60% of recurrent cost of aquaculture operation (Eyo, 2013). Expensive feeds could negatively affect the profitability of fish farming through incapacitating the expansion of farms to increase production and consequently, low yield in term of quality and quantity of fishes (Gabriel et al., 2007). Aquaculture has traditionally relied on products from industrial fisheries; namely fish meal and oil which are most expensive global resource. The global fish meal price has increased more than two fold in recent years (FAO, 2013). In Asia alone, the production of fish feed increased from 40% in 2000 to 60% in 2008 while the fish meal consumption for tilapia increased from 0.8 million tons to 1.7 million tons during same period (Tacon and Metian, 2015). Despite the increase in fish feed prices, the farm gate prices of aquaculture products have remained static, literally impinging on the economic viability of thousands of small-scale producers that form the backbone of the aquaculture sector (Rana, 2009). Indeed, the increasing price of feed ingredients (fish meal, fish oil and cereal), energy and transportation costs have complicated the availability of aqua-feeds to many fish farmers worldwide. This global phenomenon could influence small-scale producers to change businesses and/or result to poverty, vulnerability and loss of livelihood especially in developing countries (Rana, 2009). Fish feeds account for the highest operational costs in aquaculture with protein being the most expensive diet (Munguti et al., 2012). Fish Meal (FM) is the most expensive protein source in aquaculture feeds (Amaya et al., 2007). Fish require high proportion of protein in their diet because they metabolize protein as energy source (Aladetohun and Sogbesan, 2013).The development of commercial aqua-feeds has been traditionally based on fish meal as the main protein source with high protein content and balanced Essential Amino Acid (EAA) profile (Agbo et al.,2015).

The need to increase food production for the ever-increasing population of people in the world including Nigeria cannot be over emphasized. To solve these problems there is the need to exploit any available food resources. The most important food content that promotes growth and good health is protein. Sources of protein readily available apart from poultry are fish and plant proteins resources. Since fish feed account for 60% of recurrent cost of aquaculture operation, therefore this research may reduce the economic burden to the aquaculturist through finding °cheap and available protein supplement (Omeru and Solomon, 2016). The efficiency of production and growth of fish in the cultural system depends on feeding complete feed at levels not exceeding the dietary requirement of the fish (Krome et al. 2014) .The choice of O .niloticus among other fish species was due to availability of the species in almost all freshwater bodies in Nigeria and also it is among the commonest accepted fish in our local markets. Nile tilapia is highly culturable of a high fecundity, which make it breed even in captivity (FAO, 2013). Oreochromis niloticus is highly palatable. Nile tilapia is among few fish species that are cultured by many aqua-culturists, this is because it is disease resistant, could be cultured in small water bodies and is a good converter of feeds (FAO, 2013).

To replace the soya bean meal with soya bean offal meal in the diet of Oreochromis niloticus.