MICRO-INGREDIENTS
Impact of phosphate sources on apparent P digestibility in juvenile Litopenaeus vannamei Jean-Gabriel Reynaud, Phosphea
Phosphorus (P) is an essential micromineral for fish as it contributes to skeleton and exoskeleton maintenance and formation. It is also involved in cellular energy production or in muscle tissue synthesis (NRC, 2011; Milián-Sorribes et al., 2021; Truong et al., 2022). P is mainly supplied by feeding as P concentration in water and phosphorus absorption through gills are low (Lall & Kaushik, 2021). Fishmeal is the main source of protein and phosphorus in aquafeed, but it is step-bystep replaced by plant protein ingredients due to the increase in its price and its lower availability (Morales et al., 2018). However, phosphorus coming from these raw materials is mainly in phytate form, a P-form less available for fish due to their low level of intestinal phytase (Milián-Sorribes et al., 2021; Truong et al., 2022). Dietary deficiency of P leads to several problems such as reduced growth, bone mineralization and fecundity or an increase FCR and fat flesh (Lall, 2002; Mabroke et al., 2013). Supplementation with inorganic feed phosphate (IFP), a common and stable source of phosphorus, is
Table 1. Water parameters, mean (s.d.)
Salinity (ppt)
34.7 (0.26)
Temperature (°C)
30.1 (0.27)
Dissolved oxygen (mg/L)
5.80 (0.22)
Dissolved oxygen (%)
86.9 (2.16)
pH
8.13 (0.09)
Alcalinity (mg CaCO3/L)
118.7 (5.75)
Amminia-N (mg/L)
0.15 (0.05)
Nitrite (mg/L)
0.15 (0.05)
nowadays a good solution to meet P requirements for fish (Morales et al., 2018). Several IFP exist on the market with different characteristics (P content, P water solubility, calcium content or pH). Thus, P digestibility and retention and P level released in the water can vary depending on IFP source (Lall, 2002; Hua & Bureau, 2006; Hossain & Yoshimatsu, 2014; Morales et al., 2018; Hossain et al., 2020). Today, there is still a lack of data on P requirements and digestibility data in fish in general and especially in crustaceans (Truong et al., 2022).
Table 2. Inorganic feed phospate inclusion and nutrient profile, mean (s.d.)
28
Negative CTRL
MCP
MAP
MSP
Inclusion rate (%)
-
1.20
1.00
1.10
Moisture (g/100g)
6.53 (0.19)
5.88 (0.09)
5.59 (0.24)
5.81 (0.25)
Crude protein (g/100g)
38.6 (0.31)
38.0 (0.21)
38.6 (0.34)
37.9 (0.25)
Lipid (g/100g)
7.29 (0.20)
7.48 (0.13)
7.41 (0.05)
7.57 (0.10)
Ash (g/100g)
3.55 (0.01)
4.23 (0.02)
4.00 (0.06)
4.15 (0.08)
P (mg/kg)
4,720 (14.1)
7,900 (113.1)
7,860 (14.1)
7,915 (49.5)
Ca (mg/kg)
1,805 (63.6)
3,675 (106.0)
1,755 (7.07)
1,820 (14.1)
Cr2O3 (g/100g)
0.40 (0.00)
0.40 (0.02)
0.42 (0.02)
0.42 (0.00)
Aquafeed: Advances in Processing & Formulation Vol 15 Issue 4 2023