Effects of increasing protein level on the performance, enzyme activity and body composition of the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879)

Abstract

A six-week growth trial was performed to estimate the dietary protein requirements for maximum growth of juvenile Brazilian sardine (Sardinella brasiliensis) based on growth performance, feed utilization, body composition and digestive enzyme activity.Six isoenergetic diets were formulated to contain protein levels that increased from 250 to 500 g/kg. Each diet was randomly assigned to triplicate groups of 160 fish with mean initial body weight of 0.93 ± 0.13 g, which were fed four times a day to apparent satiation. Growth tended to increase with the increase in the dietary protein level up to 400 g/kg. Total protein intake was indirectly correlated to apparent protein utilization. No significant differences in whole-body composition were found between fish fed the different protein levels. Acid protease and neutral lipase activities did not show significant differences among the different protein dietary groups. Alkaline protease activity increased in fish fed up to 350 g/kg of protein and amylase activity in fish fed up to 400 g/kg. Using polynomial regression, 367 g/kg was estimated to be the optimum dietary protein requirement for maximum weight gain of juvenile Brazilian sardines. K E Y W O R D Sbrazilian sardine, digestive enzymes, feed, protein requirement, Sardinella brasiliensis

Effect of dietary protein levels on the growth, enzyme activity, and immunological status of Culter mongolicus fingerlings

“…The results of this study showed that the 100% survival of C. mongolicus fingerlings, indicating an adaptation to a wide range of dietary protein levels. These findings are similar to these of previous studies on Brazilian sardine [8], Rhamdia quelen [13], Nibea diacanthus juveniles [17], Dabry's sturgeon juveniles [54], bluegill sunfish juveniles [55], and juvenile marbled spinefoot rabbit fish [56]. These results suggest that dietary protein levels may not be a determinant factor of the mortality.…”

“…than the values reported for the fingerlings of similar sizes, such as those of Sardinella brasiliensis, 36.77% [8], Horabagrus brachysoma, 39.10% [60] and Lepomis macrochirus, 41.51% ~42.37% [55]. However, it is similar to the dietary protein requirements for some commonly cultured carnivorous species, viz., Salmo salar (48%) and Oncorhynchus mykiss (48%) [3].…”

“…However, excessive protein content may have no further benefits for individual growth and may even induce growth retardation due to the higher energy cost of extra protein metabolism [3,57,58]. Similar tendencies were found in several other fish species, such as the Brazilian sardine [8], juvenile bluegill sunfish [55], and juvenile red spotted grouper [59]. The optimum dietary protein requirement for C. mongolicus is about 49%.…”

“…In contrast, excessive protein cannot be fully digested and causes the accumulation of toxic nitrogen in the body, which restrains the activity of trypsin [67,68]. Various studies have reported that lipase activity was the same across different dietary protein treatments because of the constant lipid content in the diet of some species, such as Pseudoplatystoma corruscans [69], Labeo rohita fingerlings [61], and Sardinella brasiliensis [8]. In the present study, we found that lipase activity showed a similar trend of variability to that of trypsin.…”

“…Protein is broken down into smaller molecules in the gastrointestinal tract, which secrete fluids, electrolytes, and digestive enzymes that allow the absorption and utilization of free amino acids [4]. Dietary protein deficiency results in retarded growth and poor health [5][6][7][8]. On the other hand, excessive dietary protein can promote ammonia excretion and increase utilization of energy for amino acid catabolism, leading to water pollution and retarded growth [9,10].…”