Dietary supplementation of cumin (Cuminum cyminum) preventing streptococcal disease during first-feeding of Mozambique tilapia (Oreochromis mossambicus)

This study was conducted to investigate the effect of dietary cumin (Cuminum cyminum) powder (CP) as a feed additive on growth performance and disease resistance during first-feeding of Mozamique tilapia (Oreochromis mossambicus). Five isonitrogenous (40% crude protein) and isocaloric (18.9 kj g-1) diets were formulated to contain 0 (control), 0.5, 1, 1.5, and 2.0% CP. In a 45-day feeding trial, 15 plastic tanks (21 L) were stocked with 40 fry (0.012 ± 0.001 g) each. After feeding experiment, fish were infected with Streptococcus iniae and mortalities were recorded. The second-order polynomial regression indicated that a dietary CP level of 1.14% provided the best survival rate challenge infection with S. iniae, growth performance and feed utilization. In conclusion, CP can be used as growth promoter to improve feed utilization and weight gain in tilapia fry, and it can be also used as an antimicrobial agent during first-feeding of O. mossambicus. Therefore, CP can be suggested as an alternative to antibiotics in controlling streptococcal disease in tilapia culture

A preliminary study of the effect of phytoadditive carvacrol on the trace elements (Cu, Mn and Zn) content in fish tissues

Phytoadditives have gained increasing interest as feed additives for fish. The aim of the present study was to determine whether selected dietary phytoadditive can influence the bioavailability of several trace elements (Cu, Mn and Zn), which play an important role in the physiological processes. The experiments were carried out at a commercial trout farm. A total of 420 juvenile rainbow trout (mean weight ± SD = 10.79±0.57), Oncorhynchus mykiss, were randomly allocated into four different treatments with three replicates each. Fish were kept in raceways (3X0.8X0.4 m) at 10±1°C with a natural photoperiod. Proper amount of carvacrol was sprayed on 1 kg of commercial trout diet to prepare four diets with 0 (Control, C0), 1 (C1), 3 (C3) and 5 (C5) carvacrol g/kg diet. Fish were fed to apparent satiation three times per day. The feeding trial lasted four weeks. Then, in different type of fish tissues (muscle, liver and pyloric caeca) from fish fed with diets enriched in carvacrol, beneficial elements (Cu, Mn and Zn) were analysed by atomic adsorption spectrophotometer. Results showed that the levels of Cu, Zn and Mn were especially significantly increase by C1 diet in all tissues (muscle, liver and pyloric caeca) except muscle and pyloric caeca Zn. The results of this experiment indicate that the carvacrol had the ability to potentiate the trace element retention. Although bioaccumulations of Cu, Zn and Mn in the muscle, liver and pyloric caeca are well demonstrated, the exact mechanisms of phytoadditives are still only partially understood. More investigations are required to detail the mechanisms involved in phytoadditives this enhancement