Available phosphorus (AP) requirement for tambaqui (Colossoma macropomum) was evaluated using different response parameters, and CT scanning was used to determine the adequacy of dietary P along with bone mineralization data. A total of 192 tambaqui juveniles (17 ± 0.85 g) were stocked into 24 70 L-tanks using randomized block design (different floors) with six treatments (1.3, 2.4, 4.8, 6.3, 7.8 and 8.8 g kg⁻¹ AP) and four replicates. Fish were fed ad libitum with six semi-purified diets containing graded levels of AP for 90 days. The dietary AP requirement was estimated using non-linear regression models. No mortality or apparent signs of P deficiency were observed. Increasing dietary AP levels improved all performance variables. Dietary P levels significantly affected bone density. The estimated P requirement for tambaqui was 6.3, 3.68, 5.0 and 6.91 g kg⁻¹ diet for improved weight gain, bone density, vertebrae mineralization and carcass mineral deposition, respectively. CT scanning allowed the visualization of bone structures affected by P deficiency and could predict the P requirement based on vertebrae mineralization. Additionally, blood chemistry parameters were significantly affected by the dietary P level, except for serum calcium. Thus, the use of 6.3 g kg⁻¹ AP in tambaqui diets can maintain normal growth and bone mineralization of juveniles from 17–150 g.

中文翻译：

---

一种利用 CT 扫描量化大牡蛎磷需求的新方法

使用不同的响应参数评估了 tambaqui ( Colossoma macropomum)的有效磷 (AP) 需求，并使用 CT 扫描确定膳食 P 的充足性以及骨矿化数据。总共 192 只 tambaqui 幼鱼 (17 ± 0.85 g) 被放养到 24 70 个 L 槽中，采用随机区组设计（不同楼层）进行六次处理（1.3、2.4、4.8、6.3、7.8 和 8.8 g kg ^-1AP）和四个重复。用六种含有分级水平 AP 的半纯化饲料随意喂鱼 90 天。使用非线性回归模型估计膳食 AP 需求。没有观察到死亡或明显的缺磷迹象。增加膳食 AP 水平可以改善所有性能变量。膳食 P 水平显着影响骨密度。tambaqui 的估计 P 需求量为 6.3、3.68、5.0 和 6.91 g kg ^-1分别用于改善体重增加、骨密度、椎骨矿化和胴体矿物质沉积的饮食。CT 扫描可以显示受 P 缺乏影响的骨骼结构，并可以根据椎骨矿化预测 P 需求。此外，除了血清钙外，血液化学参数受膳食 P 水平的显着影响。因此，在 tambaqui 日粮中使用 6.3 g kg ^-1 AP 可以维持 17-150 g 幼鱼的正常生长和骨矿化。