Improper dietary protein to carbohydrate ratio causes abnormal visceral fat deposition, hampering gonadal development and breeding performance in Labeo Catla female

Abstract

The availability of balanced diet is critical for reproductive success in fish. A feeding trial on Labeo catla females was carried out in earthen pond to assess the effect of different dietary protein to carbohydrate ratio on gonad maturation and breeding performance. Three feed D-I (Feed-I), D-II (Feed-II) and D-III (Feed-III) were formulated with varying ratio of Ground Nut Oil Cake (GNOC) and rice bran (2:1, 1:1 and 1:2) and fed for 120 days. To assess the gonad maturation events, GSI VSI, breeding, fatty acid analysis, sex hormone profiling, cholesterol, triglyceride and histological examinations were conducted. Fish groups fed with D-III exhibited the highest VSI and visceral fat (VF) deposition, followed by those fed with D-I, whereas groups fed with D-II showed significantly lower levels (P<0.05). The result of GSI was completely opposite to values of VSI. Ovarian histology showed less number of mature oocytes in D-I & D-III treatments and more mature oocytes in D-II. Breeding results showed that fishes fed with D-I and D-III hampered gonad maturation whereas fish fed with D-II responded towards spawning, fertilization, and hatching. Increased levels of testosterone, estradiol, and vitellogenin (Vtg) were observed in the D-II fed group whereas increased level of progesterone was observed in D-I fed group followed by D-II and D-III. Serum cholesterol was higher in the D-III and D-I group. Visceral fat accumulation prior to ovarian maturation is a normal phenomenon in this species which serves as a lipid reservoir required for the later transfer to the gonad as yolk or is utilized as an energy source for gonad maturation. However higher level of protein or carbohydrate in the diet disrupted normal gonad maturation and lead to abnormal visceral fat accumulation, sex steroid level, failure in spawning response and seed production.