No abstract

Tilapias are becoming increasingly popular culture fish because of their superior culture adaptability. In recent years, there has been a great interest in the use of probiotics in fish aquaculture. The objectives of the present study were to evaluate the effect of dietary graded levels (0, 5, 10, and 15 g/kg commercial diet, referred to treatments numbers T1, T2, T3, and T4, for males and T5, T6, T7, and T8 treatments for females) of a new probiotic Hydroyeast Aquaculture(®) on hematological and biochemical parameters, serum sex hormones, and the reproductive efficiency parameters of the adult Nile tilapia Oreochromis niloticus for 8 weeks. Results revealed that high levels of probiotics diet, 15 g (T4, ♂) and 10 g (T7, ♀) probiotic/kg diet, significantly (P ≤ 0.05) enhanced the physiological responses (hematological as well as serum biochemical parameters) together with, reproductive performances (sex hormones, testes and sperm quality parameters, absolute and relative fecundity, and ovarian measurements). Therefore, it could be conclude that Hydroyeast Aquaculture(®) is useful at levels of 15 g (T4) and 10 g (T7)/kg diet in improving the reproductive efficiency of adult O. niloticus males and females, respectively. Thus, the use of Hydroyeast Aquaculture(®) may be economically important for fish hatcheries.

Chromium has been recognized as a new and important micro-nutrient, essential for both human and animal nutrition. This study was conducted to evaluate the appropriateness and/or the use of safety level of dietary chromium picolinate (Cr-Pic), and its effects on the physiological responses, the histometric characteristics, and the chemical analysis of dorsal muscles of mono-sex Nile tilapia, Oreochromis niloticus. A total of 420 fingerlings (28.00 ± 0.96 g) were randomly distributed into 21 fiberglass tanks representing seven treatments at a rate of 20 fish m−3. The control fish group (T1) was fed a Cr-Pic free basal diet. Other fish groups were fed the basal diet supplemented with 200 (T2), 400 (T3), 600 (T4), 800 (T5), 1000 (T6) and 1200 μg Cr-Pic kg−1 diet (T7). Diets were offered to fish at a feeding rate of 3% of life body weight for 12 weeks. Results revealed that blood hematological parameters (hemoglobin, red blood cells, packed cell volume, mean corpuscular hemoglobin concentration, blood platelets, and white blood cells lymphocytes); serum biochemical measurements (total testosterone, high density lipoprotein, total protein, albumin, and globulin); and the dry matter and crude protein of the fish dorsal muscles all have significantly increased (P ⩽ 0.05) in the T3 treatment compared with the other treatments. Meanwhile, no significant differences were found among all treatments with regard to the histometric characteristics. It can be concluded that Cr-Pic at 400 μg kg−1 diet (T3) seems to be the most appropriate level for O. niloticus fingerlings.

The objective of the present study was to determine the effects of dietary inclusion of different levels of pawpaw seeds powder (PSP) at different periods on the growth performance, survival rate, feed utilization and carcass composition of fry and fingerlings of Nile tilapia (Oreochromis niloticus). The experiment was divided into two periods; the first was feeding period of Nile tilapia fry with PSP for 71 days; and, the second was rearing period where the Nile tilapia fingerlings fed control diet (0 g/kg diet from PSP) for 84 days. Apparently-healthy 1200 Nile tilapia fry of one day old with an average initial body weight 0.012 g/fry were randomly distributed to 20 treatments. Each treatment was referred to three aquaria. The PSP was added to the basal diet at levels of 0, 2, 4, 6 and 8 g/kg diet for 15, 30, 45 and 60 days, different periods. The results of the first period showed no significant (P ≥ 0.05) differences in all growth performance parameters and feed conversion ratio (FCR) during all periods (15, 30, 45 and 60 day); however, different levels of PSP showed significant (P ≤ 0.01) improvement in all growth performance, survival (intervals SR and final SR) and feed utilization (FI and FCR) by increasing level of PSP till 6 g PSP/ kg diet, then significantly decrease (P ≤ 0.01) till 8 g PSP / kg diet. In case of the second period, all growth performance parameters and feed utilization (FI and FCR) gradually (P ≤ 0.01) improved with increasing feeding periods until 45 day, and then decreased with increasing feeding period (60 day). The interaction between levels of PSP and different periods of treatment indicated that 6 g PSP/kg diet for 45 day had the best (P ≤ 0.01) values of FW, TWG and ADG compared with other treatments. Thus, the results of this study lead to useful and safety recommended use of 6 g PSP /kg diet for 45 day, to be economic and efficient for fish farms.

Breast feeding results in lower aflatoxin exposure. Also, a strong association between aflatoxin exposure and impaired child's growth exists.