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ARS Home » Pacific West Area » Aberdeen, Idaho » Small Grains and Potato Germplasm Research » Research » Publications at this Location » Publication #224224
Title: The effect of protein source and vitamin premix on growth efficiency of rainbow trout, Oncorhynchus mykiss.

Author
item Barrows, Frederic
item Gaylord, Thomas
item SEALEY, WENDY - UNIV OF ID, HAGERMAN, ID
item SMITH, CHARLIE - BOZEMAN, MT
item PORTER, LUCAS - UNIV OF ID, HAGERMAN, ID

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2008
Publication Date: 7/15/2008
Citation: Barrows, F., Gaylord, T.G., Sealey, W.M., Smith, C.E., Porter, L. 2008. The effect of protein source and vitamin premix on growth efficiency of rainbow trout, Oncorhynchus mykiss.. Aquaculture 283:148-155.

Interpretive Summary: Trout diet formulations have changed considerably in the last 10 years due to changing ingredient markets, feed processing technologies, and faster growing strains of trout. The content of fish meal in the feeds has decreased over this time period due to economic, environmental, and sustainability issues. Feed processing method has also changed from compression pellets to the higher temperature and pressure method of cooking extrusion, which has been shown to reduce levels of some vitamins. The vitamin requirements of fish are affected by age and fish size and vitamins represent a small but significant portion of the cost of fish feed. For these reasons, a study was conducted to determine the effect of protein source and vitamin levels in extruded feeds on growth performance and nutrient retention. Two protein sources, fish meal and plant meals, were ech fed with each of 4 vitamin premixes containing the same vitamins but at different levels. The premixes were based upon reported requirements by the National Research Council (1993) but adjusted for losses due to extrusion processing and storage. Symptoms of a pantothenic acid deficiency were observed within 6 weeks for the fish fed the plant based, negative control diet (no vitamins added), and symptoms of a Vitamin E deficiency were observed for the trout fed the fish meal, negative control diet (no vitamins added). These treatments were terminated after 9 weeks. Comparing among the supplemented diets, vitamin premix did affect survival, feed intake, nutrient retention, liver size and blood values, but not weight gain. The vitamin levels recommended by National Research Council do not appear to be adequate for young, fast growing trout fed extruded feeds. Adjustment of individual vitamins in the premix to account for vitamin retention through the extrusion process will maintain levels in the final feed above target levels, and reduce vitamin costs relative to over-supplementation of all vitamins.

Technical Abstract: Trout diet formulations have changed considerably in the last 10 years due to changing ingredient markets, feed processing technologies, and faster growing strains of trout. The content of fish meal in the feeds has decreased over this time period due to economic, environmental, and sustainability issues. Feed processing method has also changed from compression pellets to the higher temperature and pressure method of cooking extrusion, which has been shown to reduce levels of some vitamins. The vitamin requirements of fish are affected by age and fish size and vitamins represent a small but significant portion of the cost of fish feed. For these reasons, a study was conducted to determine the effect of protein source and vitamin levels in extruded feeds on growth performance and nutrient retention. A 2 by 4 factorial treatment design was used with 2 protein sources, fish meal and plant meals, and 4 vitamin premixes containing the same vitamins but at different levels. Vitamin premixes included; 1) 100% of NRC (1993) recommendations (100). 2) the same profile but with each vitamin adjusted for extrusion losses independently, variable retention (VR) . 3) all vitamins adjusted to assume equal retention of 40% after extrusion (ER). 4) negative control with no vitamins added (None). Each of the 8 diets was fed to groups of 35 rainbow trout (4.8 g) in 150-L fiberglass tanks (5 replicate tanks per diet, except for the negative control diets with 3 replicates) for 15 weeks. Each tank was supplied with 6 L/min of untreated, constant temperature (14.5ºC), spring water. Symptoms of a pantothenic acid deficiency were observed within 6 weeks for the fish fed the plant based, negative control diet, and symptoms of a Vitamin E deficiency were observed for the trout fed the fish meal, negative control diet. These treatments were terminated after 9 weeks. Comparing among the supplemented diets, vitamin premix did affect survival, feed intake, PRE, ERE, hematocrit and HSI, but not weight gain or FCR. Body composition was affected by both protein source and vitamin premix. Vitamin retentions after extrusion were similar to reported values with the exception of Vitamin A, folic acid, and thiamin. The vitamin levels recommended by NRC do not appear to be adequate for young, fast growing trout fed extruded feeds. Adjustment of individual vitamins in the premix to account for vitamin retention through the extrusion process will maintain levels in the final feed above target levels, and reduce vitamin costs relative to over-supplementation of all vitamins.