Abstract
A 6-week feeding strategy experiment was conducted to investigate the effects of time-dependent protein restriction and subsequent recovery on shrimp. Diets with protein levels of 43 and 36% were used as adequate and restricted diets, respectively. Shrimp with an initial body weight of 6.52 ± 0.46 g were given four feeding strategies: feeding on an adequate diet for six weeks (T1, the control), having protein-restricted diet in weeks 1 and 4 (T2), being given a protein-restricted diet in weeks 1, 3, and 5 (T3), and having protein-restricted diet in weeks 1, 2, 4, and 5 (T4). WG, SGR, FE, and PER of shrimp in T1–T3 showed no significant difference (P > 0.05), these indicators of T4 were significantly reduced (P < 0.05). No significant differences were found in digestive enzyme activities of shrimp among all treatments (P > 0.05). Crude protein content of shrimp muscle in T4 was lower than that of T1–T3. The expression level of tor in T4 was lower than that in other treatments, while 4e-bp was higher than that of other treatments. To balance saving on feeding cost and growth performance, giving the shrimp a protein-restricted diet for 1 week with subsequent refeeding (T2 and T3) is suitable for shrimp under high-density conditions.
Highlights
The success of culturing shrimp depends on maximizing the cost-effectiveness of production
If excess protein is provided, it will be metabolized as an energy source rather than used for growth, and excess protein may increase the excretion of nitrogen into the aquatic environment, reducing water quality and growth performance (Ali et al, 2003; Dong et al, 2013)
At the end of the feeding experiment, the growth-related parameters in all experiments were affected by different feeding strategies (P < 0.05, Table 4)
Summary
The success of culturing shrimp depends on maximizing the cost-effectiveness of production. It is very popular to use plant protein instead of fish meal or to increase the level of lipids or carbohydrates in the diet to spare dietary protein (Ding et al, 2015; GarcíaOrtega et al, 2016; Xie et al, 2016; Salas-Leiton et al, 2018; Mock et al, 2019). Compared with these dietary protein management strategies, the use of protein-restricted feeding to improve protein utilization has attracted the attention of aquatic nutritionists
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