| Environmental stress can break the harmony relationship between environment andshrimps, causing the physiological disorder of the shrimps. We selected some typicalenvironmental stress factors including stocking density, starvation, ammonia nitrogen andfeeding frequency in super-intensive culture conditions, and studied the effects of thesestress factors on behavior, growth, metabolism, biochemical composition, energy budgetand non-special immunity factors (phenoloxidase-PO, catalsse-CAT, superoxidedismutase-SOD, malondialdehyde-MDA) in Macrobrachium rosenbergii and Litopenaeusvannamei. The main results are as follows.1) Effects of stocking densities on behavior and energy budget in Macrobrachiumrosenbergii The experiment was conducted to determine the effects of stocking densities(30, 60, 90, 150 individuals-m-2) on behavior and energy budget in Macrobrachiumrosenbergii. The results showed that the movement frequency, aggressive acts number,oxygen consumption and ammonia excretion rate were increased with increasing stockingdensities. Energy budget was allocated less to the growth in high density group than in lowgroup, while those to the metabolism and excretion were increased.2) Effects of starvation stress on behavior in Macrobrachium rosenbergii Theinfluences of starvation (0, 1, 3, 6, 9 days) on the locomotion, aggression, feeding andterritory behavior of Macrobrachium rosenbergii were investigated. The results indicatedthat the movement frequency increased first, then decreased, but the aggressive actsnumber decreased significantly. After the shrimps were refed, feeding frequency andterritory behavior enhanced first, and then slowed down with starvation time extension.3) Effects of ammonia-N stress on behavior, growth and physiological activity inLitopenaeus vannamei To study the effects of ammonia-N stress on behavior, growth,energy budget and non-special immunity factors in Litopenaeus vannamei, fourammonia-N levels of 0.05 (the control), 1.0, 2.5 and 5.0 mg·L-1 were designed. Asammonia-N concentration increase, the specific growth rate, activity levels,swimming-walking distance, PO activity and CAT activity decrease gradually, while SODactivity and MDA level increased. Energy budget was allocated less to the growth with theincreasing of ammonia-N concentrations, while that to the metabolism was increased. Theresults performed that ammonia-N stress could result in declining activity levels,decreasing the food ingestion and energy utilization efficiency, and damaging non-specific immune functions in shrimps.4) Effects of stocking densities on behavior, growth and physiological activity inLitopenaeus vannamei Effects of stocking densities stress on behavior, growth andphysiological activity in Litopenaeus vannamei were investigated. The results showed thatthe movement frequency, swimming-walking distance, oxygen consumption and ammoniaexcretion rate were increased with increasing stocking densities. Energy budget wasallocated less to the growth in high density group than in low group, while those to themetabolism and excretion were increased. The CAT activity and MDA level for density of80 ind·m-2～160 ind·m-2 were increased gradually with increasing stocking densities andtimes, but PO activity and SOD activity increased first after stress, then droped. It isconsidered that higher densities lead to higher energy consumption and lower immuneactivities in shrimps.5) Effects of starvation stress on behavior in Litopenaeus vannamei A 12-day trialwith video-based movement analysis system was conducted to investigate behaviors inLitopenaeus vannamei on starvation and satiation. The results showed that: 1) during Day1 to Day 4, the movement frequency in day time and swimming-walking speed of fastedshrimps had no significant difference from fed shrimps. 2) during Day 5 to Day 8, themovement frequency in day time was significantly higher in fasted shrimps than in fedshrimps. 3) during Day 9 to Day 12, the diurnal movement frequency andswimming-walking speed of fasted shrimps were significantly lower than those of fedshrimps. Under the starved condition, shrimps decreased activity levels for energy saving.And 6) Effects of feeding frequency on behavior and immune function in Litopenaeusvannamei The experiment was conducted for 30 days in order to determine the effectsof different feeding frequencies (over-feeding 1, 2 and 6 times per day respectively) onbehavior, growth and non-special immunity factors in Litopenaeus vannamei. The specificgrowth rate, activity levels and swimming-walking distance increased progressively asfeeding frequency increased. When feeding 1 time per day, the activities of PO, CAT andSOD of the shrimp declined with the time, but MDA level increased. During theexperiment, the values four indexes of shrimp with feeding 2 times per days were noobvious change. When feeding 6 times per day, the activities of PO, CAT, SOD and MDAlevel of the shrimp rose slowly.
|
PDF Full Text Request