Kim Jauncey

Growth and protein utilization by juvenile catfish (Clarias gariepinus) fed dry diets containing co-dried lactic-acid-fermented fish-silage and protein feedstuffs.

Fish-silage (FS), prepared from lactic acid fermentation of whole tilapias, 5% sugar beet molasses and 2% Lactobacillus plantarum, was blended and co-dried with soybean meal (SBM), poultry by-product meal (PBM), hydrolysed feather meal (HFM) and meat and bone meal (MBM). The blends were evaluated as protein source (providing 50% of dietary protein) in dry diets (40% protein, 4·3 kcal g−1 gross energy) for juvenile catfish, Clarias gariepinus, fed at 4% body weight day−1 for 70 days. The fish-silage pellets maintained their shape during water immersion and their water stability was high and similar (P>0·05) to that of a reference diet. Clarias gariepinus fed on the different fish-silage diets showed some significant (P 0·05). Protein digestibility was reduced (P<0·05) in catfish fed diets containing FS: HFM while digestibility of energy content was lower (P<0·05) in those fed diets containing FS:SBM and these low values were responsible for the poor performance of catfish in both treatments. There were no effects among treatments on carcass composition, hepatosomatic index, histology of pancreas, liver and intestine tissues, or on haematocrit and haemoglobin contents. Fermented fish-silage codried with protein feedstuffs is a suitable protein supplement, which can provide up to 50% of dietary protein without affecting feed efficiency, fish growth or health.

Water stability, nutrient leaching and nutritional properties of moist fermented fish silage diets

Fermented fish silage was prepared from whole mixed-sex tilapia (Oreochromis niloticus), 15% molasses and 5% Lactobacillus plantarum starter culture and used as protein source in tilapia diets. Four alternative binders (carboxymethyl cellulose, corn starch, guar gum or wheat gluten) were incorporated in diets at 3% and their effects on water stability and nutrient leaching were determined. Water stability of the pellets showed that high physical stability of the pellets was maintained regardless of the binder used, and losses of total nitrogen were low (< 3%) on a per gram diet recovered basis. All-male O. niloticus fingerlings (mean weight, 48·9 g) were fed the appropriate diets at a rate of 5% of body weight per day, twice daily, for 30 days in a recirculated water system with water temperature maintained at 27°C. Apparent digestibility coefficients for dry matter, nitrogen or lipid in the diets were high and similar when carboxymethyl cellulose, corn starch or wheat gluten was used as the binder; but were reduced (P < 0·05) with guar gum.

Chemical and nutritional quality of raw, cooked and salted fish silages.

Abstract Fermented fish silages were prepared from whole tilapia ( Oreochromis niloticus ), molasses and Lactobacillus plantarum starter culture. The effects of cooking and addition of 5% salt on the proximate composition, various protein and lipid quality parameters were measured over a 30-day period of incubation at 30°C. The silages were stable during fermentation and storage, and no appreciable loss of nutrient contents was noted. The changes observed were increased degree of autolysis and ammonia production. Addition of salt or cooking of substrate before fermentation prevented continued protein hydrolysis by inhibiting the activity of endogenous autolyzing enzymes and decreased the formation of total volatile bases. The apparent digestibility of dry matter, of nitrogen and of the energy content of silage-based diets for tilapia was higher in both the cooked and salted fish silages than in the raw fish silage.

Chemical and nutritional quality of stored fermented fish (Tilapia) silage

Abstract Fermented fish silage was produced from minced tilapia ( Oreochromis niloticus ), 15% molasses and 5% Lactobacillus plantarum culture. Initially, batches of the fish silages were fermented at 5, 20, 30 or 35°C for 30 days. The pH declined rapidly at 20, 30 and 35°C but at 5°C, pH decline was slower. Protein solubilization (autolysis) in the fish silages was temperature-dependent as the non-protein nitrogen content (NPN) increased rapidly at higher temperatures. In a second experiment, fish silage was fermented at 30°C for 7 days after which autolysis was halted, then stored at 30°C for 180 days and analysed at intervals. The NPN attained a maximum of 51·4% of total nitrogen content after 180 days. Proximate composition of tilapia silages varied slightly during storage and there was a slight loss of tryptophan during fermentation and storage. The stored wet tilapia silages were blended with soybean meal (1:1, w/w) and dried. The nutritional value of co-dried tilapia silage as a dietary protein supplement for catfish ( Clarias gariepinus ) was studied in digestibility experiments. Although the protein quality of wet tilapia silage was reduced during storage, there were no differences ( P > 0·05) in the apparent protein digestibility coefficients of diets containing co-dried tilapia silages. It is suggested that autolysis in the stored tilapia silages had little effect on proten digestibility in the catfish.

Growth and protein utilization by juvenile catfish (Clarias gariepinus) fed moist diets containing autolysed protein from stored lactic-acid-fermented fish-silage

Fermented fish-silage was prepared from whole tilapias, 15% molasses and 5% Lactobacillus plantarum starter culture and used as protein supplement in moist diets for juvenile catfish, Clarias gariepinus. Carboxymethyl cellulose, guar gum or wheat gluten was incorporated as alternative binder into diets at 2% and their effects on water stability and nutrient leaching were determined. The pellets maintained a high water stability regardless of the binder used, and losses of total nitrogen were low (<8%) on a per gram diet recovered basis. Apparent digestibility coefficients for dry matter, nitrogen or lipid in the diets were high and similar when carboxymethyl cellulose or wheat gluten was used as the binder; but were reduced (P<0.05) with guar gum. C. gariepinus (mean weight, 18.5±1.3 g) were fed silage diets at 5% of body weight/day, twice daily, for 70 days in a recirculated water system with water temperature maintained at 27°C. Growth was better or similar when some of the protein was supplied by silage stored for 15 or 30 days, respectively. Differences in growth and protein utilization were demonstrated, but there were no effects on body (fillet) composition. The results showed that incorporation of autolysed protein in fish diets did not reduce dietary quality of feed for C. gariepinus. No morphological deformities were observed It is concluded that fermented silage stored for 15 days is beneficial as protein supplement in aquafeeds.

The Potential of Groundnut (Arachis hypogaea L.) By-Products as Alternative Protein Sources in the Diet of Nile Tilapia (Oreochromis niloticus)

The nutritional suitability and cost effectiveness of groundnut cake (GNC) and groundnut husk (GNH) as protein sources in the diet of Nile tilapia (Oreochromis niloticus), mean initial weight 4.24 ± 0.20 g, was evaluated over a 56-day growth period. Five isonitrogenous (320 gkg−1), isolipidic (100 gkg−1), and isoenergetic (18 KJg−1) test diets were formulated in which GNC proteins replaced fish meal (FM) protein at levels of 25% and 50%, and GNH protein at 10% and 20%. The control diet had FM as the sole protein source. The growth experiment was conducted in plastic tanks in a recirculation system; each dietary treatment was in triplicate. After feeding fish at 4%–6% body weight per day, GNC and GNH protein replacements up to 50% and 20%, respectively, did not significantly (P < 0.05) affect growth and feed utilization. The study indicated that GNC and GNH protein could replace at least 50% and 20% of fish meal protein, respectively, in the diet of O. niloticus fingerlings without adversely affecting growth, feed efficiency, whole body composition, and nutrient digestibility. Generally the GN by-products-based diets were more cost-effective than the fish meal-based diet, particularly GNH replacing 20% fish meal protein.

Influence of a sodium formate/formic acid mixture on growth of juvenile common carp (Cyprinus carpio) fed different fishmeal replacement levels of detoxified Jatropha curcas kernel meal in practical, mixed diets

ABSTRACT Intensification of cyprinid production has resulted in substantial increases in aquafeed demand for these species and a requirement for studies on new protein sources. Increased availability of presscakes from biodiesel crops may help to meet this requirement. The suitability of detoxified Jatropha curcas kernel meal (JKM), in combination with a dietary organic acid/salt blend (NDF), was tested in practical diets for juvenile common carp (Cyprinus carpio). Four treatment diets contained between 0% and 13.5% fishmeal with the fishmeal protein replaced by JKM (0%, 30%, 70%, and 100%). Four further diets of the same composition but including 0.5% NDF were also prepared, and all diets were fed to carps for eight weeks. There were no statistical differences in growth between diets containing JKM and the control. Furthermore, addition of dietary NDF significantly improved final weights, specific growth rates, feed conversion ratios, and protein efficiency ratios. Body composition analysis showed a significant impact of dietary JKM inclusion on increasing body lipid content. The addition of NDF showed a tendency to lower body lipid content (P = 0.11). JKM is a suitable protein source in diets for carp, and the inclusion of 0.5% of NDF proved to be beneficial.