| China is a major exporter of tilapia farming and tilapia aquaculture species in China, and which plays a very important position. But in recent years, due to individual small tilapia farming, quality and safety, feed costs and water environment and other factors, the healthy development of tilapia industry subject to a certain degree of control. In view of this, the paper selection of important commercial fish farming tilapia (Oreochromis niloticu x O-aureus) as test subjects, freshwater ecosystems in the room for growth test. Comparison of different dietary calcium and phosphorus levels on the growth of hybrid tilapia status, physical function and deposition of mineral in the body, of tilapia dietary calcium and phosphorus on the tolerance to determine the aquatic Add the appropriate amount of feed.This study used body length2.30±0.12cm, weight3.02±0.06g physical health within the scope of tilapia, holding culture throughout the trial period is divided into two stages of the period and culture, including holding culture for7day culture period of60days. Test with4×3factorial design, completely randomized block, each set three levels of factor3, a total of12treatments, each set three repeat treatments. Feed the two factors are calcium and phosphorus ratio, calcium levels were added:0.1%,0.2%,0.4%,0.8%, P addition levels (2:1,1:1,1:2) are0.5×[Ca]%,1×[Ca]%,2×[Ca]%. Tests were carried out67days, test results are as follows:1. Growth:significantly affected tilapia body weight, weight gain, feed conversion ratio of dietary calcium and phosphorus levels; Dietary calcium and phosphorus ratio is1:2,which is on the best growth than the other calcium and phosphorus ratio. With adding calcium and phosphorus ratio1:2in the feed,0.4%added calcium is increased the level of tilapia the highest weight; with adding0.4%calcium level,0.8%of phosphorus levels on the maximum growth rate of tilapia. With adding calcium and phosphorus levels in the feed is0.4%and0.8%, it is the greatest impact on the final weight of tilapia, and feed coefficient of the lowest.2. Nutrition:in the Feed, regardlessly, the level of calcium and phosphorus added changed is no significantly effect to the crude protein, crude fat rate, water rate system in antiptia, but be significantly effect to increased tilapia ash, calcium and phosphorus content. Following the level of calcium added0.4%,ash content is lagerest, and with the no levels of phosphorus supplement, ash increased is not very obvious. With0.4%calcium level, the calcium content of the body is most affected, the level of phosphorus is0.8%of added P body highest;3. Physiological indicators:With ietary calcium and phosphorus levels, adding calcium and phosphorus ratio is1:2in the feed, adding0.4%calcium content of the highest level of serum calcium (3.58mmol/L),0.4%adding calcium content of the highest serum phosphorus level (4.68mmol/L);0.2%adding calcium level was the highest total bile acid (18.97mmol/L), adding the calcium and phosphorus calcium ratio2:1,0.1%added serum total protein level was the highest (56.33mmol/L); the calcium and phosphorus added ratio1:1,0.2%Ca added the maximum level of alanine aminotransferase (661.67U/L); with increased levels of dietary calcium and phosphorus added decreased cholinesterase activity, in the0.05%phosphorus adding level of cholinesterase activity maximum (2180.67U/L).4. Adding appropriate of calcium and phosphorus:Considering the growth rate of the best, Adding calcium and phosphorus ratio is1:2best fit in the feed;dietary calcium0.4%added level was calcium deposition largest, adding calcium levels appropriate to range from0.2%to0.8%. Adding dietary0.8%phosphorus level is the largest phosphate deposits, and add a level appropriate to the range of phosphorus0.4%～1.6%. |
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