Hamda Azmat

Role of phytase supplementation in improving nutrient digestibility and growth performance for Labeo rohita fingerlings fed on canola meal-based diet

ABSTRACT The present feeding trial was conducted to assess the optimal level of phytase supplementation required for maximum nutrient absorption and growth performance of Labeo rohita fingerlings fed canola meal-based diet. A standard diet having 30.21% protein and an energy value of 4.26 kcalg−1 was used as reference diet. The experimental diet having similar protein and caloric density was formulated by using 70% reference diet and 30% of canola meal as test ingredient. This experimental diet was then divided into seven test diets and were supplemented by graded levels (0, 250, 500, 750, 1000, 1250 and 1500 FTU kg−1) of phytase enzyme. Chromic oxide was used in reference and test diets as an inert marker. Results showed that phytase supplementation at 750 FTU kg−1 level effectively increased apparent digestibility coefficients of crude protein (64%), crude fat (76%) and gross energy (68%) as compared to reference and other phytase-supplemented diets. The results of present study showed increased growth and feed performance of fingerlings in response to phytase supplementation. Maximum performance was obtained by the fish fed on test diet having 750 FTU kg−1 level. It was concluded that 750 FTU kg−1 level of phytase supplementation in canola meal-based diet is sufficient for increasing nutrient digestibility and growth performance of L. rohita fingerlings.

Effect of varying stocking density of bottom feeder fish Cirrhinus mrigala and Cyprinus carpio on growth performance and fish yield in polyculture system

The present project was planned to study gradual replacement of Cirrhinus mrigala with Cyprinus carpio and its impact on pond ecosystem. A total of 900 fishes belonging to six species viz. Catla catla, Labeo rohita, Cirrhinus mrigala, Ctenopharyngodon idella, Hypophythylmichthys molitrix and Cyprinus carpio were stocked in four earthen ponds. The dimensions of each pond were 220 × 198 × 7 feet length, breadth and depth. The stocking density in pond 1 (T1) was C. catla 150, L. rohita 200, C. mrigala 200, C. idella 150, H. molitrix 150 and C. carpio 50. The stocking density of C. mrigala and C. carpio in pond 2 (T2) was 150 and 100, in pond 3 (T3), 100 and 150 and in pond 4 (T4) it was 50 and 200, respectively while the stocking density of all the other four fish species remained constant in all the four ponds. All the fish were fed with a diet of 25.16% crude protein at 2% body weight. C. idella and C. mrigala showed maximum growth in T1, C. catla and H. molitrix in T2, L. rohita and C. carpio in T3. Maximum growth was observed in T3 followed by T4, T1 and T2. Among fish species C. idella and C. carpio showed higher growth rates than the rest of fish species. Our results reveal that in polyculture system stocking density of C. mrigala and C. carpio in a ratio of 1: 1.5 gives better results. Key words: Aquaculture, freshwater, phytoplankton, zooplankton, exotic fish.

Evaluation of Fish Health Status and Histopathology in Gills and Liver Due to Metal Contaminated Sediments Exposure

Health status of freshwater fish, Cirrhina mrigala was studied by qualitative and quantitative histopathological analysis, alterations in frequency/prevalence percentages (%) and histological alteration indices (HAI) in response to metal contaminated sediments of the River Ravi aquatic ecosystem. Histo-structures of gill and liver samples of fish were analyzed and comparison between the degree of damage of the alterations in fish organs was performed after exposure to metal contaminated sediments for 7, 14 and 28 days under semi-static water renewal bioassays. Histopathological studies revealed marked histological alterations in the gills and liver of exposed fish as compared to normal tissue structure observed in control fish. The frequency and prevalence percentages observed in 28-day exposed fish were significantly higher as compared to 7- and 14-day exposed fish. The order of frequency and prevalence percentage for gills and liver of exposed fish was as: 28-day > 14-day > 7-day. The highest prevalence percentages recorded were 83 and 80% as focal area of necrosis in gill and liver, respectively, after 28-day exposure. The lowest prevalence percentage observed in 7-day exposed Cirrhina mrigala was dilation of sinusoids (17%).

Nutritive evaluation of fish acid silage in Labeo rohita fingerlings feed

Viscera of various fish species was collected during local harvest at the Department of Fisheries and Aquaculture, Ravi Campus, University of Veterinary and Animal Sciences, Lahore pond facility. Acid silage was prepared by systematic applications of formic acid. The proximate analysis of the product revealed 5.16 ± 0.65% moisture, 32.17 ± 0.12% crude protein, 9.56 ± 0.14% lipids and 6.50 ± 0.32% ash contents. Total microbial aerobic plate count was 1.69 × 104± 0.06 × 103 cfu g−1 while the coliforms were recorded as 0.97 × 104± 0.02 × 103 cfu g−1. The pure silage was free of aflatoxins B1, B2 and G1 and G2; however, microbial load and aflatoxin values vary in different feed ratios. The feeding trial showed significant change in all three feeds prepared from different ratios of silage; nevertheless, feed containing 75% acid silage showed better growth in Labeo rohita fingerling diet when compared with its counterparts. Our studies suggest that the fish silage can be a cheaper and effective alternative to fishmeal in fish feeds, if carefully handled and properly processed. This is because fish silage is prepared from fish waste body viscera, which is utilized neither in human nor in animal feeds in the raw form. On the other hand, fishmeal is a main and expensive ingredient used in livestock and fish feeds. Utilization of fishmeal is on the rise while its production is on decline, which is continuously escalating its price. Furthermore, the manufacturing of fish silage is simple and requires relatively lesser inputs as compared to fishmeal manufacturing.