Effect of different diet pellet sizes on the growth of juvenile cobia (Rachycentron canadum)

ABSTRACT It is known that there is a close relationship between pellet feed size and fish growth. However, the magnitude of this relationship regarding an animals’ feed efficiency is not yet clear. Therefore, the present study conducted at the Virginia Tech - Virginia Seafood Agricultural Research and Extension Center (USA), investigated the effects of three different pellet feed sizes, 1.7mm (EP.1), 2.3 mm (EP.2) and 3.1 mm (EP.3), on the growth of Cobia (Rachycentron canadum) in a recirculating aquaculture system (RAS). Animals were farmed for 55 days in 77.5-liter tanks (6 fish with an initial density of 3.78 g L⁻¹) weighing approximately 41.83±1.24g. The results showed that during the 8-week culture period, there were no significant differences between the animal’s final weight over the different pellet feed sizes (EP.1 - 952.5±40.7g; EP.2 - 1014.5±26.6g; EP.3 - 1030.0±54.8g). However, biomass gain showed significant differences (EP.1 - 704.0±34+.3g; EP.2 - 763.0±27.8g; EP.3 -776.5±51.9g). Consequently, significant differences were also found in the feed conversion factors.

摘要：众所周知，颗粒饲料粒径与鱼类生长之间存在密切关联，但该关联对于动物饲料利用效率的影响程度尚不明确。本研究于美国弗吉尼亚理工大学-弗吉尼亚海鲜农业研究与推广中心（Virginia Tech - Virginia Seafood Agricultural Research and Extension Center）开展，旨在探究三种不同粒径的颗粒饲料——1.7mm（EP.1）、2.3mm（EP.2）及3.1mm（EP.3）——对循环水养殖系统（recirculating aquaculture system, RAS）中军曹鱼（Rachycentron canadum）生长性能的影响。试验于77.5升的养殖缸中进行，每缸投放6尾初始体质量约为41.83±1.24g的军曹鱼，初始养殖密度为3.78 g L⁻¹，养殖周期为55天。结果显示，在8周的养殖周期内，不同饲料粒径组的军曹鱼终体重无显著差异（EP.1组：952.5±40.7g；EP.2组：1014.5±26.6g；EP.3组：1030.0±54.8g）。但各组的生物量增重存在显著差异（EP.1组：704.0±34.3g；EP.2组：763.0±27.8g；EP.3组：776.5±51.9g）。因此，各组间的饲料转换系数也存在显著差异。