The use of yttrium oxide and the effect of faecal collection timing for determining the apparent digestibility of minerals and trace elements in Atlantic salmon (Salmo salar, L.) feeds.

摘要

The effectiveness of the external marker yttrium oxide (Y2O3) and sampling period for determining the apparent digestibility (AD) of minerals and trace elements within Atlantic salmon feeds were compared. Yttrium oxide was compared at inclusions of 0.01, 0.1, 1 and 10 g kg-1 wet weight of the feeds. Samples were analysed for a range of mineral and trace elements via inductively coupled plasma optical emission spectroscopy after wet decomposition with concentrated nitric acid. Feed marked with 1 g kg-1 provided the greatest recovery, and provided analytical values within an optimal range, and therefore, the effect of faecal sampling period on AD of mineral and trace element was then compared using the feed marked with 1 g kg-1 Y2O3. Faeces were collected over three different time periods within a 24 h period: 4x6 h, 2x12 h and 1x24 h. Magnesium, manganese, phosphorus, iron and chromium displayed significant differences in AD relating to sampling period. An inclusion level of 1 g kg-1 Y2O3 and faecal sampling over at least an 18 h period after feeding proved to be the most effective method of determining AD of mineral and trace element in Atlantic salmon feed.