This article presents the results of studies of the chemical composition of the fish meat while using as a feed additive zeolite of Chankanay origin. The research was conducted during 2011-2013 at the Department of Veterinary-sanitary examination and hygiene of the Kazakh National Agrarian University and at the laboratory of JSC ‘Kazakh Academy of Nutrition’ LTD ‘NUTRITEST’. The material of study was the zeolitic tuff of Chankanay deposit (Almaty region) and two-year trout Oncorhynchus mykiss. For the research we used feed by recipes of GosNIORH - 12-80. The chemical composition of fish meat was determined by a set of methods: moisture by drying at 105 °C, fats by Soxhlet, total protein by modified Kjeldahl method (ISO 937:1974), and minerals by incineration in a muffle furnace. Calorie content of meat was determined by Alexandrov’s formula: X = C - (F+A) ´ 4.1 + F ´ 9.3. Fatty acid composition of fish meat was determined by gas-liquid chromatography. Thus, the results are the indirect evidence that zeolites added to primary diet for growing fish, do not adversely impact proteolytic enzyme systems of fish, that is, have no negative effect on fish organism.

Smoked sprats (Sprattus sprattus balticus) from the Baltic Sea are one of the most popular processed fish products in Latvia. The amount of catching and demand is annually increasing. For producers, it is important to provide stable quality throughout the year, which sometimes is challenging due to many factors. Smoked fish quality depends not only on the seasonality, but also on the applied technologies. The aim of the current study was to review research findings about factors affecting the smoked fish quality. The databases of Science Direct, Web of Science, Wiley Online Journals and Google Scholar were searched. The first parameter that affects quality of fish till processing is raw material, its catching place and season, as well as whether it is fresh or frozen fish, that includes not only microbiological parameters, but also physical and chemical changes in fish depending on the storage conditions. The second parameter is the applied pre-treatment methods (using salt, acids) before processing, which can improve fish texture and make better result for smoked fish. The third parameter is the used technology for the fish processing, heat treatment methods use of wood chips or liquid smoke, or adjustment of smoking conditions. These all together make a lot of sensorial and textural changes in the final product. If any of these parameters is changed during processing, they can affect the smoked fish quality. Therefore, to ensure constant quality of smoked fish, in-depth knowledge of parameters is extremely important.

The growth response of Tilapia fish (Oreochromis niloticus) to supplementation with fresh or dried leaves of a sweet variety of cassava was studied in 1 m deep ponds (each 4 m * 2.5 m * 1 m). Rice bran or rice bran mixed with cassava root meal was provided as the energy source (20-24% of feed DM), the mixed feed being given at the rate of 5% of fish LW. There were 30 fish per pond with average initial weight of 6 g per head. The treatments were arranged as a 2*2 factorial in a Completely Randomized Design (CRD) with 4 replicates. The first factor was cassava leaf processing (sun-dried or fresh); the second factor was energy source (rice bran or rice bran mixed with cassava root meal). The cassava leaves and roots were from a local “sweet” variety traditionally planted by farmers for human consumption. The experiment was conducted for 100 days. Daily gain in weight and length, and the ratio weight: length after 100 days of growth, did not differ among treatments. All the fish survived and there was no evidence of HCN toxicity. Water quality parameters were not affected by the treatments. There were no interactions between sources of protein and of energy. It is concluded that the feeding of cassava leaves with rice bran can be readily adopted by small scale farmers as both these feed resources are readily available in rural areas.