By: Dr Mustapha ABA, Aquaculture Researcher, Fish Nutrition. Morocco.
Research into aquaculture broodstock nutrition is gaining importance with the increasing use of domesticated and genetically selected stocks for aquaculture. Feed quality plays an important role in aquaculture production, as it is a major determinant of animal growth and reproductive efficiency and therefore the profitability of the aquaculture business.
Adequate diets are essential for egg development, spawning, follicle formation, ovarian tissue formation, embryo growth and development. Foods must be formulated to meet the nutritional needs of the broodstock, an essential factor in achieving the desired quality of gametes and larvae. For these reasons, aquaculturists and feed manufacturers must give more importance to the feeding of fish spawners in aquaculture, hence the need for high quality nutrient supplementation, especially at the beginning of gonadal development period.
Many studies of aquatics organisms have used physical, biological, or biochemical parameters as indicators of broodstock reproductive performance and egg quality .
In aquaculture, the broodstock nutrition is one of the most important constituents for many cultured fish species , they have unpredictable and variable reproductive performance is an important limiting factor for maturation, fecundity, and survival of larvae.
Research into fish broodstock nutrition is gaining importance with the increasing use of domesticated and genetically selected stocks for aquaculture.
Egg quality and spawning performance were related to the nutritional state of the broodstock and suboptimal nutrition effects the availability of essential biochemical constituents required for gametogenesis and reproductive control.
Given the increasing importance of domestication in aquaculture, there is a need for an increased focus on the role of nutrition in broodstock and maturation performance and in increasing larval survival and quality will be fundamental to obtaining optimal performance from domesticated stocks.
The improvement of maturation performance and larval production remains a key goal in improving the efficiency of production systems.
Among fish’s dietary components, such as proteins and lipids, have been implicated in various reproduction-related processes, such as gonadal maturation, gamete quality, and spawning perfor-mances.
Thus, broodstock diets should be formulated to ensure all essential nutrients requirements are met for the fish species being cultured.
Proteins and lipids stand out as the most important nutrients for formation of body tissues . Moreover, both nutrients play a major role in reproduction, since they have a direct influence on embryonic development .
Therefore, the development of broodstock feeds rests with there requirements in this stade.
- Role of broodstock nutrition on fish embryo development
Le régime alimentaire des géniteurs, contenant tous les nutriments essentiels affecte le développement de l’embryon, améliore la morphologie de l’œuf et taux d’éclosion. Plusieurs études ont montré que le développement de l’embryon est affecté par les taux des acides gras et les vitamines E, Cet A.
- Role of Broodstock nutrition on larval quality
Seed quality improves with the increase in the quality of the nutrition of the broodstock. The diet rich in unsaturated fatty acids increases the percentage of live larvae after yolk resorption and improves larvae’ weights and their ability to resist osmotic shock.
- The feed has a direct Role of broodstock nutrition and on fish fecundity
Fertility is defined as the total number of eggs produced by each fish expressed either in terms of eggs per spawning or eggs per body weight.
Several studies have shown that fertility is affected by a nutritional deficiency of lipids and unsaturated fatty acids.
- Lipids are the most studied macronutrient in terms of broodstock nutrition.
One of the major nutritional factors that has been significantly affect reproductive performance in fish is the dietary essential fatty acid content.
Most fish species preferentially utilize lipids to provide energy for somatic growth but they are also a source of essential fatty acids (EFA) required for the formation of cell membranes that are vital for successful larval development. It is therefore important that the correct EFA are provided, in excess of requirement levels, to allow the production of robust and healthy larvae.
In this context, the fish feed must require more content of lipids in order to satisfy the energy needs but also the production needs of quality gametes and larvae. Several studies have shown a close relationship between lipids and the fatty acid composition of the broodstock diets and the gametes and larvae produced by these broodstock.
- Requirements of Proteins and Amino-Acids in Broodstock Nutrition
Proteins are the most important nutrient in fish nutrition because they are the building blocks of the animal body at all stages of development and are responsible for the formation of enzymes and hormones. In addition, proteins are present in fish egg protein such as lipoproteins, hormones….and enzymes, determining egg quality and, therefore, fish production on a large scale.
Several studies have shown that a high protein diet provided to the spawning stock accelerates gonadal maturation in fish, a high egg survival rate, an influence on gonadal maturation in fish and food in the body.