In the recent decades, global production of farmed tilapia has grown exponentially. Further expansion and intensification of tilapia farming bring some challenges including raising feed cost and environmental impact. These specific challenges are directly related to feed composition and nutritional quality, and need to be addressed by formulating diets more efficiently. Swine and poultry industry have made significant advancements in precision nutrition approach by formulating diets on digestible nutrient basis, following ideal protein concept and metabolizable or net energy system. Feed cost is largely influenced by dietary protein levels and sources. Quality of the dietary protein is determined by its amino acid composition and digestibility in relation to the requirements of fish. Efficient use of various protein sources and improvements in protein utilization require more precise understandings of raw material digestibility and amino acid requirements of tilapia. This paper aims to give an overview of data generated on nutrient digestibility of raw materials and the amino acid requirements of Nile tilapia.
Considerable work have been done on the raw material digestibility of tilapia in the past years. Our recent work (G. Konnert and K. Masagounder 2017) critically reviewed 46 papers published on raw material digestibility. Over the years, improvements have been made on standardizing methodology for determining nutrient digestibility of raw materials in fish. Considering this, we carefully evaluated and excluded data that may have produced erroneous values. Finally, our summary data included amino acid digestibility of 24 raw materials derived from 10 papers, and crude protein and energy digestibility of 35 raw materials pooled from 15 papers. Briefly, raw materials such as fish meal, soybean meal, soy protein concentrate, and corn gluten meal showed very high (>90%) apparent digestibility coefficients (ADC) for protein and amino acids. Amino acid ADC values were generally good (80-90%) for poultry byproduct meal and canola meal, while those for raw materials such as meat and bone meal and feather meal showed high variability.
On the amino acid requirements of Nile tilapia, several studies (n >20) have been published. Studies have largely focused on juvenile stages of tilapia and showed high variability in the requirement data. Variability of data may be related to factors including genetic improvements, feed quality, nutrient digestibility, model used, experimental conditions, among others. Recently, factorial model was applied to generate amino acid recommendations for different stages of tilapia by incorporating data on amino acid gain, maintenance needs and utilization for growth. Furthermore, based on the contribution of natural food, and their amino acid profile, amino acids recommendations were also suggested for different farming system. Overall, these data can be used to formulate more efficient tilapia diets, leaving a positive impact on sustainable growth of tilapia production.