Development and assessment of novel endogenous markers in commercial aquafeeds to measure apparent digestibility in large Atlantic salmon (Salmo salar) on salmon farms

• Published in: Aquaculture Vol. 508; pp. 192 - 198
• Main Authors: Witkowski, Stephen J., Carter, Chris G., Grünenwald, Martin, Hadley, Scott, MacLeod, Catriona K.A., Townsend, Ashley T., Adams, Louise R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-06-2019
• Subjects: Apparent digestibility; Digestibility marker; Lutetium; Nitrogen; Protein; Digestibility marker; Apparent digestibility; Nitrogen; Lutetium; Protein
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2019.05.005

As salmon aquaculture continues to grow, understanding aquafeed conversion is imperative for making informed strategic growth planning and management decisions. Accurately measuring the apparent digestibility (AD) of commercial aquafeeds on farms requires greater understanding and method development, including the validation of one or more inert endogenous AD markers. Laboratory and commercial experiments assessed the potential of elements that naturally occur in aquafeeds as potential endogenous AD markers. Two commonly used and validated AD markers, acid insoluble ash (an endogenous marker) and ytterbium oxide (an exogenous marker) were compared using protein AD calculated from a range of endogenous elements. Using a Percentage Similarity Analysis, comparison of protein digestibility calculated with recognised AD markers demonstrated lutetium (Lu) was the most accurate endogenous AD marker. Identification of Lu as an effective endogenous AD marker in commercial salmon aquafeeds will facilitate the straightforward measurement of AD under commercial conditions. This work has important applications in salmon aquaculture where protein AD is fundamental to growth efficiency.
•The use of endogenous markers for calculating apparent digestibility for fish under commercial conditions was assessed.•No change to commercial practice or the commercial feed were required to use the endogenous markers tested.•The research is significant because factors that influence apparent digestibility under commercial aquaculture operations can be determined more easily.