The present study was conducted to assess the effects of combined and singular dietary administration of PrimaLac® and potassium diformate (KDF) on growth performance, feed utilization, digestive enzymes activity, and some physiological parameters of rainbow trout (Oncorhynchus mykiss) juvenile. Three hundred sixty rainbow trout juveniles (25 ± 1.8 g) were randomly stocked in 300-L tanks (30 fish/tank), and fed three times daily on a basal diet (control), diets incorporated with 12 g kg⁻¹ KDF (FT₁), 1.5 g kg⁻¹ PrimaLac® (FT₂), and combination of 1.5 g kg⁻¹ probiotic and 12 g kg⁻¹ KDF (FT₃) in triplicates, for 8 weeks. At the end of feeding trial, growth performance, body composition, digestive enzymes, liver enzymes, and biochemical parameters were measured. Our results revealed that combined administration of PrimaLac® and KDF (FT₃) exhibited significantly higher weight gain and specific growth rate (SGR) compared to other groups (P < 0.05). Glucose and cortisol levels showed no significant differences between fish fed different test diets (P > 0.05). The highest lipase, protease and amylase activity were observed in group of fish fed FT₃ followed by FT₂ and FT₁. Besides, the diets FT₂ and FT₃ led to significantly lower of ALP, ALT, and AST compared to control group. The present results indicated that combined administration of PrimaLac® and KDF can be considered as a beneficial feed additive and growth promotor for O. mykiss juvenile.

中文翻译：

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日粮PrimaLac®和二甲酸钾（KDF）对虹鳟（Oncorhynchus mykiss）的生长性能和某些生理参数的综合和奇异作用。

本研究旨在评估PrimaLac®和二甲酸钾（KDF）的联合和单一饮食管理对虹鳟（Oncorhynchus mykiss）幼鱼的生长性能，饲料利用率，消化酶活性和一些生理参数的影响。将360只虹鳟鱼幼体（25±1.8 g）随机放养在300公升的水箱中（每只鱼30条鱼），并每天以基础饮食（对照）喂养3次，其中基础饮食为12 g kg ^-1 KDF（ FT ₁），1.5 g kg ^-1的PrimaLac®（FT ₂）以及1.5 g kg ^-1的益生菌和12 g kg ^-1的KDF（FT ₃），一式三份，持续8周。在喂养试验结束时，测量了生长性能，身体组成，消化酶，肝酶和生化参数。我们的结果表明，与其他组相比，PrimaLac®和KDF（FT ₃）联合给药表现出明显更高的体重增加和比生长速率（SGR）（P  <0.05）。饲喂不同测试日粮的鱼之间的葡萄糖和皮质醇水平无显着差异（P  > 0.05）。在饲喂FT ₃的鱼群中观察到最高的脂肪酶，蛋白酶和淀粉酶活性，其次是FT ₂和FT ₁。此外，饮食₂和₃与对照组相比，导致ALP，ALT和AST显着降低。本结果表明，PrimaLac®和KDF的联合给药可以被认为是有益的饲料添加剂和生长促进剂为O.虹鳟少年。