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Feeds which are typically formulated with an excess of protein are usually due to one of two reasons: either the protein is not very digestible so more has to be added to meet amino acid requirements, or excess protein is added because specific essential amino acid requirements are not known.

The excess protein provides a large margin of safety so that there will be less chance that essential amino acids are limiting in the diet. It is not economical or necessary to increase the total protein content of a feed to a point where excessive amounts of many amino acids are included in an attempt to meet the requirement for one or more of the essential amino acids that are shortest in supply.

A diet should be formulated based on digestible amino acid values of feed ingredients and an ideal protein.

The excess nitrogen excreted as ammonia by fish may have a negative impact on the environment because it is a major contributor to water pollution.

Because every species of fish and the individual proteins within each species has its own unique amino acid composition, the ideal situation would be to formulate a low protein feed that would minimize nitrogen excretion and at the same time meet all requirements for essential amino acids.

Today, in other species such as poultry and swine, this is done routinely since synthetic essential amino acids (e.g., methionine, lysine, threonine) are commercially available, and these animals utilize these synthetic amino acids efficiently.

A better understanding of the dietary nutrient requirements of cultured fish species and a continual search for accessible, highly digestible proteins to replace expensive fishmeal is essential. This approach coupled with applying the ideal protein concept in the formulation of fish feeds can greatly ameliorate nitrogen pollution arising from fish production systems and increase profitability.

The catfish and trout farms, which account for the vast majority of the food-fish produced in the United States, already have greatly reduced their use of fishmeal in feeds, to a total of around 5% in catfish diets, and a total of 20% in trout diets.

More information on the ideal protein concept is available here.

This material is drawn from document FA144, one of a series of the Department of Fisheries and Aquatic Sciences, University of Florida, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences. First Published: March 2007. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.

A new barley that benefits the environment as well as farm animals has been developed by Agricultural Research Service (ARS) scientists and their colleagues.

“Clearwater” hulless barley is rich in the kinds of phosphorus–an essential nutrient–that pigs, fish and other single-stomached, or “monogastric,” animals can use.

That’s unlike grain from conventional barleys, which contains more of the phytate type of phosphorus, the kind that monogastric animals find difficult to digest. Indigestible phosphorus, leached from manure, can sometimes end up polluting groundwater or streams.

Clearwater builds upon decades of research by plant geneticists Victor Raboy, Phil Bregitzer and others at the ARS Small Grains and Potato Germplasm Research Unit at Aberdeen, Idaho.

Raboy uses conventional plant-breeding procedures to chemically tweak seeds’ phosphorus makeup. The work has paved the way for low-phytate barleys, such as Clearwater and a hulled type called “Herald,” as well as low-phytate rice, corn and soybeans.

Bregitzer, Raboy and ARS plant geneticist Don Obert collaborated in the Clearwater research with Idaho Agricultural Experiment Station co-researchers Juliet Windes and James Whitmore. A recent article in the Journal of Plant Registrations contains more details.

Clearwater yields are about the same as those of other niche-market barleys, according to Bregitzer. One such market–aquaculture feeds–is already being explored. Approximately 46,000 pounds of Clearwater were shipped to Vietnam earlier this year by the U.S. Grains Council of Washington, D.C., and the Idaho Barley Commission to test Clearwater as a feed ingredient for farm-raised fish. ARS researchers at Hagerman, Idaho, and Bozeman, Mont., will begin similar investigations with farm-raised rainbow trout this month.

The Idaho Agricultural Experiment Station’s Foundation Seed Program at Kimberly has offered Clearwater seed for sale since late 2007. Researchers and plant breeders can contact Bregitzer to obtain, at no charge, small supplies of Clearwater or any of several other feed, food and malting barleys that have resulted from ARS and Experiment Station barley breeding research.

The lab is also conducting some research in innovative feed for trout. Additional information on this is available here.

Sea lice pose a huge health threat to both wild and farmed fish. Researchers have investigated the efficacy of a treatment for sea lice in wild sea trout.

Sea lice are important exoparasites of fish, both in the wild and in aquaculture.

These tiny crustaceans can lower the fitness of the fish and indirectly cause fatalities due to open lesions that prevent the fish from maintaining its osmotic, or salt/water balance. If infection rates are severe, the parasites can feed on the fish at higher than the growth rate. It follows then that developing stock are more prone to this distressing phenomenon due to their small size.

To investigate means of tackling this disease, wild sea trout were tagged with Passive Integrated Transponder tags (PIT tags). Fish are therefore identifiable and traceable using a tag scanner on recapture of the fish.

There were two groups, one treated with a prophylactic substance designed to control the parasite and the others untreated. The experiment took place in the north-west of Scotland.

It was discovered that the treatment had a significant effect on the condition factor of treated fish. Indices of condition indicated that the fish that received the prophylactic suffered less growth constraints whilst in open sea.

Possible subsequent effects on growth and survival to sexual maturity could have significant implications on stock conservation due to the direct relationship between fecundity and size in the female.

Control of this parasite is important, not only for farmed stocks, but also for wild stocks as farming situations are thought to act as sources of infection for this pest. Further research could well bring about more effective controls and superior management of our natural and farmed fish stocks.

More on this approach to sea lice control is available via this link.

Magnar Benjaminson, a Masters student from the Department of Administration and Organisation theory at the University of Bergen, Norway has taken note of the activities of the Finfish.org community and has sought your help. He is seeking to gain a better understanding of learning processes in aquaculture and explains his field of study below….

Norwegian salmon farming has a very long and troublesome history. The commercial part of this history is not very long though. Commercial salmon, and trout, farming in Norway before the 1960-70s had more the character of a hobby than of a commercial branch. But since then, Norwegian salmon farming has grown and become the largest and most significant national salmon producing branches of the World. The way to success was mainly build by a number of stubborn, hardworking and adventurous entrepreneurs. This is at least the way history will see it, but it is a fact that the success would be almost impossible without them.

These entrepreneurs had some things in common, besides the personal abilities I mentioned before. They were always experimenting with new production constructions, locations, types of food, etc. The result was a lot of failures, but also some significant cases of success. The innovations made by these entrepreneurs have been vital for salmon farming to become a Industry. And behind these innovations, there has been a lot of learning.

In Norway innovation has become a must for most companies, including the companies in the salmon farming branch. But there is less fuzz about the underlying processes of innovation; learning. As far as I can see there has been no research on this subject in this branch, a branch which was build up by these processes. I found out that someone has to find out whether learning has been totally neglected in this branch, or if it’s just not very much attention on the subject.

My thesis will try to recover learning processes in one of the leading farmed salmon suppliers in Norway, Bremnes Seashore. My main research issues are 1) the processes attached to acquiring new technology(or knowledge), 2) the learning processes taking place inside the organization and 3) how cooperation with/relations to other companies can result in learning processes. In addition to these questions I will focus on which level is engaged in the learning processes, the continuity of these processes and comparison over time(5 years or so).

I’m in a early stage of my work and I’m very happy if anyone is interested in commenting or giving me some feedback on this.

Magnar may be reached via his email.