Interpretive Summary: An investigation of links between metabolic rate and feed efficiency in European sea bass Dicentrarchus labrax

By Anne Zinn

A paper recently published in the Journal of Animal Science investigated the links between metabolic rate and feed efficiency in the European sea bass Dicentrarchus labrax, a major species in European mariculture. Aquaculture represents a promising source of sustainable animal protein for the growing human population, but a major factor in the significant cost of feeding the fish and the environmental impact. In addition, improving feed efficiency through selective breeding is key for sustainable finfish aquaculture but its evaluation at the individual level is technically challenging. An alternative to rearing finfish in large groups is to rear individuals singly, but this method is extremely time-consuming and laborious, which impacts application on a large scale. 

The present study, the first to assess whether individual metabolic rate is a predictor of individual feed efficiency in farmed fish, investigated whether individual routine metabolic rate was a predictor of individual feed efficiency in the European sea bass Dicentrarchus labrax. It was hypothesized that fish with greater metabolic rates may compensate by consuming more dietary energy than others when fed ad libitum, but would be unable to do so on a fixed ration.

Results demonstrated variation among European sea bass populations regarding oxygen consumption, in addition to the well-known effect of temperature on this trait. Between temperatures and among populations, fish with a lower oxygen consumption were more efficient, but at the individual level, no significant correlation was found. Although the results provided evidence of an association between metabolic rate and feed efficiency, routine metabolic rate was not a predictor of individual feed efficiency. Further research is required to fully understand the link between individual feed efficiency and oxygen consumption in fish. 

The full paper can be found on the Journal of Animal Science webpage.