Silas S.O. Hung

Nutrient partitioning in rainbow trout at different feeding rates

Effects of feed deprivation (FR=0.0), underfeeding (FR=0.3% feed/day), moderately restricted feeding (FR=1.0) and adequate feeding (FR=2.0) on nutrient partitioning in 10-month-old rainbow trout (Oncorhynchus mykiss) were studied in a 6-week growth trial at a water temperature of 15°C. Each treatment was administered to triplicate groups of individually tagged rainbow trout initially weighing 0.32 kg. Average body weight gains and feed efficiencies were significantly (P<0.05) affected by the different feeding rates. Increased feeding rates had little influence on body composition except percent carcass fat and visceral protein. Percent fat in liver, red muscle and white muscle increased significantly with increasing feeding rates. Plasma protein, insulin, glucagon, and glucagonlike peptides also increased significantly, while growth hormone decreased, but not significantly, with increasing feeding rates.

Optimum feeding rate of hatchery-produced juvenile white sturgeon (Acipenser transmontanus): at 20°C

Abstract A growth experiment was conducted to determine the optimum feeding rate for juvenile white sturgeon (Acipenser transmontanus) held at 20°C. Sturgeon were fed a purified diet from 0.5 to 4.0% (at 0.5% increments) body weight per day (BW/day) for 8 weeks. Analysis of variance showed that percent body weight increase (%BWI), feed gain ratio (FGR), final body weight, liver weight, condition factor, and whole body moisture and lipid content were significantly (P

Choline requirement of hatchery-produced juvenile white sturgeon (Acipenser transmontanus)

Abstract An 8-week growth experiment was conducted to determine the dietary protein requirement of hatchery-produced juvenile white sturgeon (Acipenser transmontanus). Twenty-five-week-old sturgeon with an initial body weight of 145.2±0.2 g (mean±SE, n=24) were fed 1.5% of their body weight per day one of the eight purified diets which contained from 20.0 to 52.7% crude protein. Protein of these diets was supplied with graded amounts of a protein mixture (casein:wheat gluten:egg white, 62:30:8). Percent body weight increase (%BWI), feed gain ratio, protein efficiency ratio, and productive protein value were significantly (P

Effect of starvation on some morphological and biochemical parameters in white sturgeon, Acipenser transmontanus

A 10 week study was conducted to determine the effect of starvation on morphological and biochemical parameters in subyearling white sturgeon. The fish were implanted with passive integrated transponder tags so that body weight change of individual fish could be determined. Ten fish were sampled once every 2 weeks. Carcass:body weight percentage, viscerosomatic index, hepatosomatic index, chemical composition of carcass and viscera, plasma glucose, protein and triacylglycerol, liver glycogen, and activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, malic enzyme, and NADP-dependent isocitrate dehydrogenase in liver tissue were measured from individual sturgeon, All parameters were significantly (P < 0.05) affected by duration of starvation. Furthermore, the results indicated that proportionally viscera lost more weight than carcass, and lipid of these tissues showed a higher reduction than protein in the 10 week starvation. This suggested that viscera was the preferred tissue over muscle, and lipid was the preferred nutrient over protein for mobilization in the subyearling white sturgeon starved for 10 weeks

Histological and histochemical changes in the digestive tract of white sturgeon larvae during ontogeny

Ontogenetic changes in digestive tract histology and digestive enzyme histochemistry were investigated 11 to 36 days post-hatch in white sturgeon Acipenser transmontanus larvae. From initiation of exogenous feeding (12 days post-hatch), larvae were fed a commercial salmonid diet for the ensuing 24 days. The digestive system of white sturgeon displayed a high degree of morphologic organization and functionality at the onset of exogenous feeding. An enhancement of digestive capacities occurred with transition to active feeding. On day 2 of feeding, there was a clear increase of alkaline phosphatase, aminopeptidase M, dipeptidyl peptidase IV, and γ-glutamyl transpeptidase activity in the brush border of the spiral intestine. This strong activity is an apparent confirmation of the importance of this segment of the intestine for protein digestion and nutrient absorption. The functional development of the pyloric intestine occurred on day 4 and was concomitant with an increase in the activity of brush border and cytoplasmic enzymes such as acetylcholinesterase, dipeptidyl peptidase II, α- and β-galactosidases. The absence of acetylcholinesterase, lactase, nonspecific esterase, and weak activity of exopeptidases and alkaline phosphatase in the anterior intestine suggests that this segment of the intestine may be less important in nutrient absorption than the pyloric and spiral intestines. The observed quantitative and qualitative differences in enzyme activity along the intestine indicate a high degree of specialization of each segment for specific digestive and absorptive processes.

Effects of feeding rate on growth performance of white sturgeon (Acipenser transmontanus) larvae

Four 1-week trials were conducted to determine the effects of feeding rates on growth performance and body proximate composition of white sturgeon larvae during each of the first 4 weeks after initiation of feeding. Feeding rates (% body weight day(-1)) were 10, 20, 30, 40, 50, and 60 for trial I; 5, 10, 15, 20, 25, and 30 for trial II; and 2.5, 5.0, 7.5, 10.5, 12.5, and 15.0 for trials III and TV Four tanks with 200 larvae each were randomly assigned to each of the six feeding rates. Average initial body weights of the larvae were 49, 94, 180, and 366 mg, respectively, for trials I-IV. The larvae were kept at 19-20 degreesC in circular tanks and fed continuously one of two commercial salmonid soft-moist feeds using automatic feeders. Proximate composition (%) of the feeds for trials I-III and IV were 13.9 and 14.9 moisture, 52.5 and 50.0 crude protein, 10.3 and 12.9 crude fat, and 8.1 and 8.7 ash, respectively. Except mortality in trial I, gain per food fed in trial III, and body ash in all trials, growth performance and body composition were significantly (Pl0.05) affected by all feeding rates. Broken line analysis on specific growth rates indicated the optimum feeding rates of white sturgeon larvae to be 26%, 13%, 11%, and 6% body weight day-respectively, for weeks 1, 2, 3, and 4 after initiation of feeding

Effect of feeding rate and water temperature on growth of juvenile white sturgeon (Acipenser transmontanus)

Abstract A 2×4 factorial experiment was conducted for 8 weeks to determine the effect of feeding rate and water temperature on the growth performance of 30-g-size white sturgeon. Body weight increase (BWI) and feed efficiency (FE) were significantly (P

Dietary effects on tissue composition, oogenesis and the reproductive performance of female rainbow trout (Oncorhynchus mykiss).

Washburn, B.S., Frye, D.J., Hung, S.S.O., Doroshov, S.I. and Conte, F.S., 1990. Dietary effects on tissue composition, oogenesis and the reproductive performance of female rainbow trout (Oncorhynchus mykiss). Aquaculture, 90: 179-195. One hundred and eighty 2-year-old female rainbow trout brood&h were fed a low protein, high carbohydrate (LP), intermediate protein and carbohydrate (IP), or a high protein, low carbohydrate (HP) diet for 9 months to determine the effect of the diets on ovarian development, body proximate composition, and reproductive performance. Dietary treatment did not have any effect on the histomorphology of ovarian development. However, during vitellogenesis (July until November), fish fed different diets had significantly different body and carcass weights, plasma glucose, and plasma vitellogenin levels. Although there were some differences between the three treatments in the proximate composition of gonads, liver, and gastrointestinal tract during the reproductive cycle, no consistent pattern was seen. At spawning, LP fish retained a higher amount of lipid in the ovaries and gastrointestinal tract than the other two groups. Although the egg proximate composition was the same regardless of diet, eggs from fish fed the LP and IP diets had significantly higher survival (P-z 0.05 ) to the eye-up stage, hatchability, and relative fecundity than HP fish.

Growth, lipogenesis and liver composition of juvenile white sturgeon fed different levels of D-glucose

Abstract Juvenile white sturgeon (Acipenser transmontanus) were fed different levels (0, 7, 14, 21, 28, 35%) of dietary D-glucose for 8 weeks. Fish fed diets with greater than 7% D-glucose had significantly (P

Effect of feeding strategy and carbohydrate source on carbohydrate utilization by white sturgeon (Acipenser transmontanus) and hybrid tilapia (Oreochromis niloticus X O-aureus)

Two 8-week growth trials were conducted to determine the effect of continuous (CF) versus 2 meals day(-1) (MF) feeding and 30% starch versus 30% glucose diets on the carbohydrate utilization of 9.0-g white sturgeon and 0.56-g hybrid tilapia. The two trials were conducted under similar conditions except that sturgeon were kept at 18.5 degrees C in a flow-through system and tilapia were kept at 26 degrees C in a recirculating system. Significantly (P less than or equal to 0.05) higher specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), body lipid content and liver glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) activities were observed in the CF than MF sturgeon. Only SGR, FE and PER were higher in sturgeon fed the starch than the glucose diets. Only higher liver G6PDH and malic enzyme (ME) activities were observed in the CF than MF tilapia but higher SGR, FE, PER and liver G6PDH, 6PGDH and ME activities were observed in tilapia fed the starch diet than those fed the glucose diet. This suggested that carbohydrate utilization by sturgeon was more affected by feeding strategy whereas tilapia was more affected by carbohydrate source. Furthermore, white sturgeon can utilize carbohydrates better than hybrid tilapia regardless of feeding strategy and carbohydrate source.