EFFECT OF DIETARY BAKER YEAST (SACCHAROMYCES
CEREVISIA) AS A FEED ADDITIVE ON GROWTH PERFORMANCE AND HEALTH STATUS OF NILE TILAPIA (OREOCHROMIS NILOTICUS).
Amal S. Hassan1 and Mohammed T. Shehab El-Din2
1Department of Fish Production and Aquaculture Systems, Central Laboratory for Aquaculture Research, Abbassa, Abo-Hammad, Sharkia, Egypt.
2Department of Fish Health, Sakha Aquaculture Research Unit, Central Laboratory for Aquaculture Research, Sakha, Kafr El-Shiekh, Egypt.
|Received 8/ 3/ 2016||
Accepted 15/ 4/ 2016
This study was carried out to evaluate the adding baker yeast (Saccharomyces cerevisae) as a feed additive on growth performance and health status of Nile tilapia, Oreochromis niloticus cultured in earthen ponds. Average of fish (20.8 g) fed on artificial diet (25% crude protein) enriched with baker yeast at levels of 0.0, 0.1, 0.2 and 0.3% (T1, T2, T3, and T4, respectively) in duplicates for 20 weeks. Each earthen pond (1 feddan) was stocked with 12000 fingerlings. The obtained results showed that the highest growth performance, survival and fish yield were obtained at T3, while T1 recorded the lowest fish growth, survival and production. Feed intake increased significantly, while FCR decreased significantly with increasing yeast levels in fish feed. Concerning the proximate chemical composition of whole-fish body, there were no significant differences in contents of dry matter and total lipids among the different treatments, while the highest protein and lowest ash contents were obtained at T3 and T4. The lowest protein and highest ash contents were found in T1. The economic evaluation revealed that optimum economic return was obtained at T3, which contained 0.2 % baker yeast. It is suggested that high fish mortality in T1 was due to the natural infection by pathogenic bacteria Flavobacterium columnare, which was isolated from different sites of skin ulcerations in fish. Many of the fish showed signs of hole-in-the head like lesions and some others exhibited severe form of saddle back like ulcer. These infections decreased as yeast levels incresaed suggesting that feeding yeast inhanced the fish resistance against F. columnare infection leading to high fish survivability. Based on the obtained results in this study it can be concluded that adding 0.2 % yeast to fish diet optimized Nile tilapia growth, survival, and production. Also, fish health against possible bacterial infection was improved when fed on a diet enriche with baker yeast.
Keywords: Nile tilapia, baker yeast, Probiotic,Fish performance, Fish health, Flavobacterium columnare.