Leading Australian Atlantic salmon farmer Tassal recently completed trials to compare feeds with low levels of fishmeal and conventional feeds.
Results showed no difference between the conventional 22-percent fishmeal feed and a 15-percent fishmeal feed made using Skretting’s MicroBalanceTM concept. An 8-percent fishmeal feed also performed well enough for Tassal to consider this as a commercial option for grower feeds in 2011.
Tassal has a strong interest in sustainability, having appointed Linda Sams, Chief Sustainability Officer to the executive management team and a sustainability team reporting to her.
“When we explained the MicroBalanceTM concept to Tassal, they were keen to test it in their own farming conditions,” says Rhys Hauler, Nutritionist and Product Manager with Skretting Australia. “We prepared two Optiline grower feeds for the trials, using the MicroBalanceTM concept. This enables us to make feeds where fishmeal levels are much lower than usual by providing alternative proteins with a range of micronutrients conventionally derived from fishmeal. One Optiline feed had 15 percent fishmeal and the other only 8 percent, both using a combination of local land animal proteins and local vegetable proteins. They were compared with an Apollo formulation with 22 percent fishmeal over a 74-day feeding period for the 15-percent formulation and 56 days with the 8-percent product.”
Several indicators were monitored. These included relative feed index and relative growth index (RGI), using Tassal’s own models, also biological and economic feed conversion ratios and mortality. Growth rates of fish in both trials were exceptional – significantly exceeding growth of all previous seasons at Tassal. “With the 15-percent formulation trial there were no statistically significant differences in any of these indicators apart from growth and that favoured the Optiline feed, which showed an RGI of 1.54 versus 1.45 for the Apollo formulation,” says Hauler. Similarly there were no statistical differences in any indicators comparing the 8 percent fishmeal Optiline diet, with some observations that favoured the Optiline diet.
Linda Sams adds, “Fishmeal is a limited resource and a key sustainability focus for Tassal and the Optiline diet means we can reduce fishmeal content without affecting the performance of our fish. This in turn supports Tassal’s objective of meeting world best practice with regard to marine resource use.”
