Exploring basic biochemical constituents in the body tissues of South African abalone Haliotis midae reared in shore-based mariculture systems

The study quantifies the effects of season, age and feeding regime on glucose, glycogen, proteins and lipids in abalone Haliotis midae tissues, and to assess water loss during simulated live export. Abalone of two age classes, younger (similar to 30 months old) and older (similar to 38 months old), were subjected to four dietary regimes: two single feeds, kelp and an artificial feed, and two rotational feeding regimes utilising kelp and the artificial feed in varying ratios. Total protein, free glucose, glycogen and total lipid content were determined in the digestive gland and foot/adductor muscle. One subset of older animals, from each feeding treatment, was subjected to water content analysis by drying. Subsets of older and younger animals were subjected to a simulated live export trial to determine mass loss. Digestive gland tissue proved to be of little value for routine monitoring. Muscle glucose, muscle lipid and muscle protein concentrations were affected by month and age. Muscle glycogen concentration was affected by month, age and feeding regime. During simulated export trials, animals lost on average 15% body mass, being significantly higher (p < 0.01) in younger compared to older animals. Feeding regime did not influence susceptibility to mass loss during export. Animal age influenced the biochemical composition and export performance of abalone.