A K Jafri

Dietary methionine requirement of fingerling Indian major carp,Cirrhinus mrigala(Hamilton)

Indian major carp, Cirrhinus mrigala fingerling (3.85 ± 0.50 cm, 0.50 ± 0.02 g) were fed isonitrogenous and isocaloric diets (40% CP, 4.28 kcal g−1, GE) containing casein, gelatin and crystalline amino acids with graded levels of L- methionine (0.50, 0.75, 1.00, 1.25, 1.50 and 2.00 g/ 100 g, dry diet) with 1.00% cystine fixed, to determine its dietary methionine requirement. A feeding trial was conducted in triplicate for six weeks. Diets were fed twice a day at 0800 and 1600 h at 5% of body weight/day. The ration size and feeding regime were worked out prior to the start of the feeding trial. Weight gain (158%) and food conversion ratio (1.45) were significantly (P < 0.05) higher in fish fed diet containing 1.00% methionine with 1.00% cystine fixed. Second degree polynomial regression analysis of the weight gain data indicated the dietary methionine requirement to be 1.20 g/100 g of dry diet, corresponding to 3.00% of dietary protein. Second degree polynomial regression analysis was also employed to determine the relationship between food conversion ratio (FCR) and dietary methionine levels which indicated that the best FCR occurred at approximately 1.20% dietary methionine level. Carcass composition of fish fed diet containing graded levels of methionine varied significantly (P < 0.05) except carcass ash content which showed insignificant (P > 0.05) differences among the dietary methionine levels.

Impact of Polyhouse Culture During Winter on Ovarian Maturity, Growth, Muscle, and Egg Composition of Carps

Abstract Impact of polyhouse culture was examined on ovarian maturity, growth, muscle and egg composition in two Indian major carps: rohu, Labeo rohitaand catla, Catla catla; and two Chinese carps: grass carp, Ctenopharyngodon idellaand silver carp, Hypophthalmichthys molitrixduring winter. Eight females (2+ years age group) of each species, were stocked in polyhouse and outdoor concrete tanks (250 m2), in duplicate. Results of the study revealed that polyhouse-cutured fishes, in general, exhibited better (P < 0.05) values for weight increment, gonadosomatic index, total number of eggs/fish, number of eggs/g body weight, and egg diameter. Proximate composition of muscle and eggs in fishes varied significantly with culture conditions. It was seen that Chinese carps attained maturity about two weeks earlier than the Indian major carps. The stage of oocyte maturation varied between fishes reared in the two culture systems. Polyhousecultured fishes possessed most oocytes (> 70%) at migrating germinal vesicle stage, while those reared in outdoor tanks exhibited these at the central germinal vesicle stage. An advancement in attainment of maturity was evident in these carps when grown in polyhouse during winter.