The Effects of Live Transport on Metabolism and Stress Responses of Abalone (Haliotis iris)

Abstract

The New Zealand abalone industry relies mostly on the export of processed products to distant Asian markets, notably China. Over the past five years, live export of high quality abalone from New Zealand has proven successful. However, transport of live animals is associated with multiple stressors that affect survival and meat quality at the end of the transport phase. Better understanding of transport-derived stress is needed to improve transport conditions and recovery at destination to ensure high product quality and safety throughout the supply chain. To this end, we applied an untargeted GC-MS-based metabolomics approach to examine the changes in metabolite profiles of abalone after a 2-day transport event and subsequent water re-immersion for 2 days. The results revealed alterations of many metabolites in the haemolymph and muscle of post-transported abalone. Decreased concentrations of many amino acids suggest high energy demands for metabolism and stress responses of transported abalone, while increases of other amino acids may indicate active osmoregulation and/or protein degradation due to oxidative stress and apoptosis. The accumulation of citric acid cycle intermediates and anaerobic end-products are suggestive of hypoxia stress and a shift from aerobic to anaerobic metabolism (resulting from aerial exposure). Interestingly, some features in the metabolite profile of reimmersed abalone resembled those of pre-transported individuals, suggesting progressive recovery after reimmersion in water. Evidence of recovery was observed in the reduction of some stress biomarkers (e.g., lactic acid, succinic acid) following reimmersion. This study revealed insights into the metabolic responses to transport stress in abalone and highlights the importance of reimmersion practices in the supply chain of live animal exports.

Keywords: GC–MS; abalone; live transportation; metabolomics; resuscitation; stress responses.

Figure 1

Effects of transport and re-immersion on normalised metabolite profiles of abalone haemolymph. (A) PLS-DA score plots. (B) Relative abundance of metabolites with VIP scores greater than 1.0. (C) Heatmap of 29 metabolites that differed among treatments. The colour bars in the PLS-DA VIP score plot and heatmap show the relative abundance of metabolites (stronger blue: lower abundance; stronger red: higher abundance).

Figure 2

Effects of transport and re-immersion on the metabolite profiles of abalone muscle tissues. (A) PLS-DA score plots. (B) Relative abundance of metabolites with VIP scores greater than 1.0. (C) Heatmap of 26 metabolites that were different among treatments. The colour bars in the PLS-DA VIP score plot and heatmap show the relative abundance of metabolites (stronger blue: lower abundance; stronger red: higher abundance).