| dc.description.abstract | Several feeding trials were conducted with juvenile hybrid striped (HSB) to determine potential effects of supplementing purified dietary nucleotides. The basal diet in these trials was formulated to contain approximately 40% protein and 10% lipid. Moreover, the nucleotide supplements were added to the basal diet at the expense of cellulose. Adenosine monophosphate (AMP), uridine monophosphate (UMP), cytidine monophosphate (CMP), guanosine monophosphate (GMP), and inosine monophosphate (IMP) were individually supplemented at 0.5% of diet and evaluated in a 9-week trial. Results showed significant enhancement of weight gain and innate immunity of fish fed the AMP-supplemented diet compared to those fed the basal diet. Furthermore, the effects of dietary AMP and IMP, each at 0.5% of diet, or combinations of both (equaling 1% of diet) were evaluated in a 9-week trial. No significant effects of AMP or IMP were observed on growth performance, whole-body composition or innate immunity; however, fish fed IMP had significant enhancement of lymphocyte proliferation compared to fish fed the basal diet. These dietary treatments were retained and evaluated for immune modulation prior to and after acute-stress challenge. Result indicated some of the dietary nucleotides provided significant enhancement of innate immunity at 0.5 h and 12 h post stress challenge, imposed by 1- minute air exposure, compared to those fed the basal diet. Supplementation of AMP at 0.5% of diet provided the greatest enhancement of innate immunity during post stress.
The minimum dietary AMP requirement was estimated based on weight gain responses in a two-slope broken-line model to be 0.5% of diet in a dose-response 8-week trial. Therefore, the AMP diet supplemented at 0.5% of dry weight was evaluated against the basal diet in four other trials. Dietary supplementation of AMP significantly improved apparent digestibility coefficients for organic matter and energy after a 4-week trial, trypsin enzymatic activity after a 8-week trial, innate immunity after a 6-week trial and acute stress challenge (air exposure), as reflected in anti-protease activity at 0.5 and 1 h after stress, and elevated plasma lysozyme and anti-protease activity after fish were subjected to chronic stress of high salinity for 4 weeks. Based on results from these various trials, this study demonstrated that an exogenous supply of AMP at 0.5% of diet was able to modulate immune responses under stressful conditions, and to a limited extent, improve growth performance, and nutrient digestibility of hybrid striped bass. | en |
