خبراء فى مجال الأسماك

الهيئة العامة لتنمية الثروة السمكية

1. INTRODUCTION

Tilapia is the main species cultured in Egypt on account of its fast growth rate, adaptability to a wide range of culture conditions and high consumer acceptability. Problems of seed supply together with the quality of the eggs and fry produced constitute one of the most important constraints on current and future aquacultural developments. Improvements of the appropriate culture conditions and managerial procedures for the broodfish are essential to produce reliably the numbers of eggs and fry required by grow-out farms.   Therefore, to achieve better management of broodstock, the effects of sex ratio, stocking density, size and age of broodfish, and feeding level on seed production of tilapia have been investigates (Siddiqui& Al-Herbi 1997; Siddiqui et al., 1997). The importance of broodfish nutrition has been well recognized (Luquet& Watanabe 1986) and the effect of different dietary protein levels (Santiago et al., 1983; Cisse 1988; Wee&Tuan 1988; DeSilva & Radampola 1990; Gunasekera et al., 1995, 1996 a,b; Ali, 2001) and lipid level (Santiago& Reyes 1993) on the reproductive performance of tilapia also have been investigated.

The feed additives have physiological and economic significance on farm animal and fish. They are added to the feed of fish to improve growth or reproductive performances and feed conversion or to control sexual development. They are commonly pharmaceutical derivatives. Although, good results were obtained with such substances, their use might have unfavorable effects (Public health hazards and/or environmental pollution). Therefore, recent efforts aim to use additive of natural origin.

          Medicinal and aromatic plants have been used as spices and medical additives. In recent years, these plants have received increasing attention as spices for human and additives in diets for animals. Spices are well known as appetizers and add flavor to otherwise insipid foods. Some of them posses antioxidant properties, antimicrobial and antibiotical activity (Mahran 1967; Boulos, 1983; Chand and Katoch, 1984; Sulliman et al., 1987; Senragle and Muller, 1990; Pradeep et al., 1991; Abd Rabo et al., 1992; El-Emary, 1993; Hanafy, 1995 Morsy, 1995).

          Considerable researches have been done on the evaluation of some feed additives of natural origin such as medicinal plants or its extractives in poultry nutrition (Ali et al., 1992;Abou-Egla et al., 1995; Hanafy, 1995; Karaly, 1995; Khalifah, 1995; Mandour et al., 1995; Morsy, 1995; Soliman et al., 1995), in ruminant nutrition (Sing and Taparia, 1992; Castro, et al., 1995; Zied, 1998; Abd El-Azeem, 1999). While, only few studies have been done on the use of such additives in fish nutrition as growth promoter (Nacario, 1983; Viola and Arieli, 1987; Ahmed and Matty, 1989; Santiago, 1991, Abd El-Maksoud et al., 1998a,b; 1999). However, there is no information in the literature showing the effect of Garlic or Fenugreek seeds as feed additives on reproductive and productive performance of Nile tilapia. Therefore, this study was conducted to evaluate the effect of Garlic and Fenugreek seeds as feed additives on reproductive and productive performance of Nile tilapia.

 

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