Optimizing the Proportions of Plant Protein Ingredients in the Diet of Juvenile Blunt Snout Bream,Megalobrama amblycephala

An 8‐wk feeding trial was conducted to evaluate the influence of different proportions of dietary plant ingredients on the growth of juvenile blunt snout bream, Megalobrama amblycephala. A 2 × 3 factorial arrangement was set for this trial with three ratios of cottonseed meal (CSM) and canola meal (CM) (2:1, 1:1, or 1:2) and three proportions of soybean meal (SBM) (2, 1, or 0). The results showed that the specific growth rate and protein efficiency ratio both significantly decreased with decreasing amounts of SBM in the diets of blunt snout bream (P < 0.05), while the feed efficiency ratio and feed intake increased significantly (P < 0.05). Meanwhile, the growth performance and feed utilization were shown to improve with increasing amounts of CSM, although the effects were not significant (P > 0.05). The interaction of these two factors had no effect on either growth or feed utilization (P > 0.05). Diet composition was not seen to affect body composition (P > 0.05). The ratio of CSM to CM significantly affected gut amylase activity, liver alanine aminotransferase content, and plasma cholesterol levels (P < 0.05). The interaction between the two main effects significantly influenced the plasma glucose level (P < 0.05). Therefore, the suitable proportion of plant feed for blunt snout bream should include high levels of SBM and CSM, with a SBM : CSM : CM ratio of 2:2:1.