ABC Four corners interview - specific discussion topics
20 October 2016
Skretting was interviewed in October by the Australian Broadcasting Corporation media program Four Corners for a report on the Tasmanian Salmon Industry. We have provided additional information on key feed topics discussed during the interview to provide some further clarification.
The Tasmanian Salmonid Growers Association website also has some further information available (click here to view). What is astaxanthin and why is it used in salmon feed?
Salmon naturally has a red/pink colour, due largely to a pigment called astaxanthin. It is produced in natural waterways by algae, yeast and bacteria. The pigment is passed on to crustaceans, such as shrimp or krill, when they eat these primary producers. Salmon then eat the crustaceans and retain the astaxanthin that they receive through their diet in the flesh and skin, where it provides vital antioxidant protection and improves robustness. It is also essential to the salmon natural reproductive cycle and can function as a pro-vitamin, being converted to vitamin A. Salmon are unable to make astaxanthin themselves, needing a dietary supply for these vital functions.
It is now possible to make the pigment directly, without the need to harvest wild crustaceans or cultivate organisms that produce astaxanthin. This form of the pigment is identical to that found in the wild food chain, and provides the same benefits to the fish. The ability to make an identical version of this nutrient increases the ability of the industry to sustainably grow without impacting other industries or depleting naturally occurring, but limited, resources. Is astaxanthin a chemical?
The term 'chemical' can be applied to anything with a known composition, including water. The term 'chemical' is commonly misused to make something appear 'unnatural' because of negative connotations related to chemical additives that are unrelated to natural substances and may be considered harmful. All substances of known composition are chemicals, including water, proteins, fatty acids, minerals and carbohydrates that make up the majority of living organisms.
Astaxanthin is a chemical with a known composition, like water, and can be synthesised. Synthesised astaxanthin has the same chemical composition as the astaxanthin found in wild salmon flesh, is approved for use as a feed additive, and has been declared safe for the human consumer by the exacting standards of the European Panel on Additives and Products or Substances used in Animal Feed (FEEDAP). Is astaxanthin harmful to humans?
No. In fact, there is a growing body of medical research that highlights astaxanthin as a valuable antioxidant for human health, and it is now included directly in nutraceutical products.
What colour would a salmon fillet be if astaxanthin is not included in the feed?
Given its health benefits in salmon feed, it is poor practice to make feeds for this species without astaxanthin, and it is not natural for salmon to be depleted of this nutrient. Salmon are not naturally white fleshed and thus farmed salmon are not naturally white fleshed. Salmon have experimentally been depleted of astaxanthin and the fillet appears similar to white-fleshed fish.
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