No abstract

Six isocaloric test diets, based on fishmeal-groundnut oil cake and containing 350-600 g kg-' protein at 50 g kg-' incremental levels were fed to snakehead, Chunna Striatu (Bloch), fry at a rate of 10% of body weight per day under laboratory conditions to determine the effect of varying level of dietary protein on the growth response. On the basis of percentage weight gain, daily weight gain, specific growth rate and daily tissue protein deposition, the dietary protein requirement of fry was found to be 550 g kg-' when fish meal was used as the major source of protein. There was a significant increase in carcass protein and a significant decrease in ash content with progressive dietary protein substitution. Fry fed with high protein diets tended to have lower carcass lipid contents and higher moisture contents.

Three isonitrogenous (320 g kg−1 crude protein, casein and gelatine) semi‐purified diets with 80 (L8), 130 (L13) and 180 (L18) g kg−1 lipid (sunflower oil at increasing levels and cod liver oil fixed at 50 g kg−1) at three digestible energy levels (12 096, 13 986 and 15 876 kJ kg−1 dry weight) and were tested, in triplicate, on rohu fingerlings (3.2 ± 0.08 g) at two different temperatures (21 and 32 °C). Fish were fed to apparent satiation, twice daily, at 09.00 and 15.00 h, 7 days a week for 56 days. Maximum growth was obtained at a lipid level of 80 g kg−1 (L8) at 21 °C (439.37%) and 130 g kg−1 (L13) at 32 °C (481.8%). In general growth rate was higher at 32 °C than at 21 °C at all lipid levels. Tissue monounsaturated fatty acid (MUFA) contents decreased with increasing lipid level at 32 °C, but the reverse occurred at 21 °C. At 21 °C, Polyunsaturated fatty acid (PUFA) level increased significantly (P > 0.05) over initial values, but was affected insignificantly by dietary lipid level. At 32 °C, fish fed diet L13 had more n‐3 fatty acid (FA) in liver and muscle than the other two dietary groups while at 21 °C, both liver and muscle FA profiles exhibited significant change (P > 0.05) in n‐3 and n‐6 FA content which corresponded to variation in percent addition of dietary lipid. However, n‐3/n‐6 ratio was higher for fish fed diet L13 at 32 °C and diet L8 at 21 °C and may be correlated with fish growth.

Abstract:Six iso-energetic (352 kcal gross energy/100 g feed) and iso-nitrogenous (32% crude protein) experimental diets containing one of the four algae (Anabaena cylindrica, AN; Nostoc salbasa, NS; Spirulina platensis, SP; Westleopsis prolifica, WS) as the major dietary ingredient (40% of the total composition) or algal meal mixture with supplemental protein (AMM+PS) or only algal meal mixture (AMM) were tested against a control diet to find out the suitability of algal meal to develop practical diet for rohu fingerling. The experimental fish of average weight 2.0 ± 0.1 g were fed at a rate equaling 4% of body wt/day for 8 weeks at an experimental temperature of 28 ± 2°C. Significant (p<0.05) enhancement in growth rate was observed in the groups fed with WS (571%) followed by the groups fed with NS (517.6%) and SP (502.8%) as compared to that of the groundnut oil, rice bran and soybean meal based control diet (406.4%). Fingerlings fed with algal meal mixture (AMM) gained least (255.2%). Diet with WS performed well in terms of FCR, PER, HSI, MR and CF when AMM showed least efficiency. Fish fed with SP showed better protein utilization (ANPU%) as compared to the other dietary groups. Carcass protein was not affected by any diet. The MUFA and PUFA of liver and PUFA of muscle increased over the initial value fed with control and experimental diets. But the MUFA of muscle with these diets are less than the initial. The SFA content in all diets of both the tissues is either same or less than initial value except with AMM diet. The total n-3PUFA in liver increased with all diets over the initial value. But this increase in muscle was observed only with AN, NS, WS and AMM+PS diets. The n-6PUFA of liver and muscle remained either same or increased with all diets over initial value. This study showed that individual algal diets gave better result in growth performance and PUFA content. Among all the algal diets WS found to be the best.

The study was undertaken to examine the capability of carbohydrate to spare protein in the diet of fringed lipped carp, Labeo fimbriatus (2.93 g±0.15). Three semi-purified experimental diets of iso-caloric nature were formulated having three graded levels of protein (27, 23 and 19% CP) and three levels of carbohydrate (26, 31.5 and 37% CHO). Accordingly, the treatments were designated as T1 (27% CP and 26% CHO), T2 (23% CP and 31.5% CHO) and T3 (19% CP and 37% CHO), where the experimental diet T1 served as the reference diet. The fish were reared in 200 l fibre reinforced plastic (FRP) tanks under continuous aeration with one third water exchanged daily. After 90 days of feeding trial, it was noticed that the percentage weight gain and specific growth rate (SGR) of 27% protein fed group (209.5±0.74% and 1.26±0.15%) and 23% protein fed group (204.8±0.52% and 1.24±0.13%) were not significantly different (p>0.05). Similarly, the results of feed performance like feed conversion ratio (FCR) among 27% protein fed group (2.24±0.11) and 23% protein fed group (2.29±0.14) did not vary significantly (p>0.05). On the other hand, the protein efficiency ratio (PER) and protein productive value (PPV) of 23% protein fed group (1.87±0.11 and 28.34±0.36) did not vary significantly (p>0.05) with the 19% protein fed group (1.93±0.12 and 27.65±0.32). The carcass protein (CP) and lipid (as ether extract,EE) content of 27% protein fed group and 23% protein fed group were not significantly different (p>0.05). Results of this study indicate that the CP level in the diet of fringed-lipped carp L. fimbriatus can be reduced from 27 to 23% by proportionately increasing carbohydrate level from 26 to 31.5% without compromising growth and also without any adverse physiological effect.