| In recent years,the growing feeding cost and high feeding quantity in the Hybrid tilapia aquaculture result in the problem of aquaculture water eutrophication pressure rising,sediment quantity of culture pond increasing,effective aquaculture space being compressed.Researching the effect of different feeding rate and feeding frequency on growth benefits,aquaculture water quality and sediment quantity of the Hybrid tilapia under the artificial ecological environment(stocking size:22.14±5.33 g,time:60 days),to explore the optimal feeding rate and feeding frequency of the Hybrid tilapia,provide scientific basis for a healthy and sustainable development of the Hybrid tilapia aquaculture.1.Within the scope of feeding rate 2%?8%,the rate of weight gain and rate of body length gain first increased and then decreased with the increasing of feeding rate.The rate of weight gain and rate of body length gain were the highest at 4%group,which were 79.36±3.31%and 16.40±0.06%,the rate of weight gain and rate of body length gain were the lowest at 2%group,which were 66.17±2.20%and 12.61±0.06%;The rate of body length gain at 4%group was very significantly higher than that of 2%group,6%group,8%group(P<0.01).2.The feed coefficient increased with the increasing of feeding rate,the unit cost first decreased and then increased with the increasing of feeding rate.The feed coefficient was the lowest at 2%group which was 0.98±0.03,the highest at 8%group which was 3.64±0.30,the feed coefficient at 2%group was significantly lower than that of 6%group,8%group(P<0.05);The unit cost of was the lowest at 4%group which was 17.95±0.12 yuan/kg,the highest at 8%group which was 28.25±0.21 yuan/kg.3.The rate of body length gain first increased and then decreased with the increasing of feeding frequency.The feed coefficient and the unit cost of first decreased and then increased with the increasing of feeding frequency.Compared with 2 times/day group,1 times/day group and continual feeding group,the rate of body length gain,feed coefficient and the unit cost were 16.72±0.09%,1.40±0.18 and 17.55±1.57 yuan/kg at the 2 times/day and no feeding 1 day in 4 days group,the rate of body length gain was up 39.33%,97.40%and 113.81%;feed coefficient was down 12.50%,19.54%and 50.70%;the unit cost was down 1.00%,8.92%and 29.54%.Compare to 1 times/day group,the rate of body length gain increased very significantly at 2 times/day group(P<0.01),the feed coefficient decreased no significantly at 2 times/day group(P>0.05);compare to 2 times/day group,the rate of body length gain increased very significantly at 2 times/day and no feeding 1 day in 4 day group(P<0.01),the feed coefficient increased no significantly at 2 times/day and no feeding 1 day in 4 day group(P>0.05);compare to 2 times/day group,the rate of body length gain decreased very significantly at continual feeding group(P<0.01),the feed coefficient increased significantly at continual feeding group(P<0.05).4.The quality of aquaculture water got bad with the increasing of feeding rate.To evaluate the quality of aquaculture water by the average content of NH3-N,NO2-N and TP,the 2%group were the best which were 0.22 ± 0.05 mg/L,0.15±0.03 mg/L and 0.19±0.05 mg/L,the 8%group were the worst which were 0.92 ±0.05 mg/L,0.34 ±0.05 mg/L and 0.51±0.03 mg/L.Compare to the 2%group,the average content of NH3-N of 4%group increased very significantly(P<0.01),compare to the 4%group,the average content of NH3-N of 6%group increased significantly(P<0.05),compare to the 6%group,the average content of NH3-N of 8%group increased no significantly(P>0.05).The Hybrid tilapia(The average weight:22.14±5.33g)aquaculture in small Cement pond,the 4%group could keep the ? grade water quality and the highest rate of body length gain.5.The quality of aquaculture water got bad with the increasing of feeding frequency,the content of NH3-N,NO2-N and TP at 2 times/day and no feeding 1 day in 4 days group were the best which were 0.16±0.05 mg/L,0.10±0.03 mg/L and 0.19±0.04mg/L.Compared to 1 times/day,2 times/day and continual feeding,the content of NH3-N was down 58.97%,61.90%and 85.71%.Compare to the 2 times/day group,the NH3-N of 2 times/day and no feeding 1 day in 4 days group decreased significantly(P<0.05),compare to the 1 times/day group,the NH3-N of 2 times/day group increased no significantly(P>0.05),compare to the 2 times/day group,the NH3-N of continual feeding group increased significantly(P<0.05).2 times/day and no feeding 1 day in 4 days group of feeding frequency could eased the pressure of the water environment and did not slow the Hybrid tilapia growth relatively.6.The sediment weight increased with the increasing of feeding rate.The sediment weight(dry weight)and sediment thickness were the lowest at the 2%group which were 18.95 ±0.95 g and 0.0006±0.00 cm/d,they were the highest at the 8%group which were 138.88 ±0.66g and 0.0047 ±0.00cm/d;The very significant increase on sediment weight between all groups(P<0.01).The service life of aquaculture pond at the 2%group was 1.92 times that of 4%group,3.66 times that of 6%group,7.30 times that of 4%under the condition of no outside sediment enter into the aquaculture water by flushing or changing water.7.the sediment weight increase with the increasing of feeding frequency.The sediment weight(dry weight)and sediment thickness were the lowest at the 1 time/day group which were 23.36 ± 1.02g and 0.0008 ±O.OOcm/d,they were the highest at the continual feeding group which were 44.38 ±0.86g and 0.0015 ±0.00 cm/d;The service life of aquaculture pond at the 1 time/day group was 1.13 times that of 2 times/day group,1.50 times that of 2 times/day and no feeding 1 day in 4 days group,1.88 times that of continual feeding group under the condition of no outside sediment enter into the aquaculture water by flushing or changing water.Above all,different feeding rate and feeding frequency have significant effect on the growth,benefit,quality of aquaculture water and the sediment of aquaculture pond.The 4%group of feeding rate and 2 times/day and no feeding 1 day in 4 days group of feeding frequency was the best,it was benefit to the balance between growth,the quality of aquaculture water and the aquaculture benefit,it can also be benefit to healthy and sustainable development of the Tilapia aquaculture. |
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