How to cope with seasonal fluctuations on your farm


Trout are farmed on outdoor farms all over Europe. Although they are a cold-water species, as with all fish, and can withstand temperature variation of 0–20°C, the ideal temperature for trout growth is between 12–16°C. Below this range, their metabolism slows down, affecting fat digestion.

As the fish’s metabolism slows down, it can take up to a few days for trout to digest a meal. A high feed rate overloads the digestive tract, and the trout is less capable of digesting food efficiently. This leads to a poorer feed conversion ratio (FCR) and more excrement, which may be visible to the farmer as a higher degree of pollution.

In intensive trout farms and farms with restricted water availability, more pollution can often be detected during the winter. This happens because the digestive tract is not accustomed to handling much food. The enzymatic processes depend on the water temperature and take place at a low rate when the water is cold, especially when the water temperature sinks to 8°C and below.

On farms, growth is desirable year-round, including in the colder months. Feeds that Alltech Coppens offers solution to winter feeding problems do well in summer often fail to yield good winter results. One important reason for this is the fish’s change in essential fatty acid requirement compared to periods of higher water temperatures. With this in mind, fish need extra care at cold temperatures.

Four main challenges during cold water periods:

• Reduced appetite, decreased feed intake

• Slower metabolism and reduced fat digestion efficiency

• Maximum feeding can lead to pollution

• Altered fatty acid requirement

Improved fat-digestible formula:

It is vital to make feed highly attractive and palatable to the trout so that the fish immediately reacts when feeding starts. For this purpose, the R&D team at Alltech Coppens has done feed trials to investigate the fat digestion and palatability of different ingredients so that the right combinations can be created, in addition to meeting the special nutritional requirements during periods of cold water.

Alltech Coppens changes the fatty acid profile in its winter feeds in order to meet the needs of trout in cold water. Furthermore, measures are taken for better fat digestion and attention is paid to the palatability of the winter feeds to ensure a good feed intake. All this allows for much better performance and less pollution during the cold winter months.

Alltech Coppens feed matches the changed requirements of the fish to provide:

► Improved digestibility in cold water – less pollution

► Enhanced fat and protein utilisation

► Good feed intake – highly palatable

► Increased biomass – stronger fish, spending less energy on coping with temperature fluctuations

Alltech Coppens customers have now switched their entire production to Alltech Coppens feed.

We really got growth over the winter, over these challenging winter months, which we actually didn’t have at all before!’

Learn more at:


Keep up with us

Posted in ,
Fish Farmer cover July 2024

The July 2024 issue of Fish Farmer is out now