Skretting Boosts Flexibility In Formulating Trout Feed

The flexibility comes from the introduction of the Skretting MicroBalance concept into Optiline trout feeds, both the standard and high energy versions. This follows validation of the concept for trout by a series of trials at the Skretting Aquaculture Research Centre (ARC) facility in Mozzecane, Italy.

In three trials trout were raised on diets formulated according to the Optiline concept of having a consistent digestible nutrient content despite using distinctly different combinations of raw materials.

Application of the MicroBalance concept on top allowed further flexibility in formulation while growth rate and feed conversion ratios remained constant. The trials began in 2010 and ended in June 2011.

Feed digestibility and efficiency

In each trial we tested multiple MicroBalance Optiline formulations against a standard formulation, says researcher Leo Nankervis at Skretting ARC.

Each feed was given to trout in three tanks with 25 trout in each, making a total of 75 fish per feed per trial. The trials began with trout at 100200g and ended after two months when they were at typical harvest size, around 300500g. We ran three sets of trials to ensure we could achieve consistent results.

All 50 freshwater tanks at the Skretting trout research facility in Mozzecane are 400 litres in capacity, have independent photoperiod and feeding controls and are equipped with a feed waste collection system. This permits researchers to calculate feed conversion ratios with high accuracy. Additionally, transparent sedimentation columns allow the researchers to study the quality of the faeces, providing further clues on feed digestibility and efficiency.

Two Options

When raw material prices fluctuate widely we have two options, says Umberto Luzzana, Product Manager Skretting Southern Europe.

We can manufacture feed to a consistent formulation in terms of raw materials inclusion to provide consistent performance but with widely changing prices or we can adjust the formulation to moderate the impact of price spikes while still providing the same digestible nutrients. The challenge in taking the second option is that it requires a deep and detailed understanding of the nutritional requirements of the trout and of the digestible nutrient content of every raw material, in accordance with the Optiline concept."

"Skretting ARC has built a bank of information on these two aspects, for trout and for other species such as European sea bass and gilthead sea bream, where Optibass and Optibream have been proven to be successful feeds. MicroBalance is a further step. It is based on providing a correct balance of micronutrients, which allows further reduction in the dependency on individual raw materials and ensures that this increased flexibility can be achieved without reduction of fish performancegrowth, feed conversion, health and flesh quality."

"The enhanced flexibility from MicroBalance has already proved that it can save money for fish farmers with species such as salmon, sea bass and sea bream. Validation of MicroBalance in trout feeds is a further important step that provides a solid basis on which to defend economic efficiency at farm level while enhancing the sustainability of farming operations.