|Rawles, Steven - Steve|
Submitted to: Aquaculture Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/14/2004
Publication Date: 10/1/2004
Citation: Gaylord, T.G., Rawles, S.D., Gatlin, D.M. 2004. Amino acid availability from animal, blended, and plant feedstuffs for hybrid striped bass (Morone chrysops x M. saxatilis). Aquaculture Nutrition. 10(5):345-352. Interpretive Summary: Hybrid striped bass (HSB) farming is an emerging U.S. industry and faces increasing competition from foreign producers. Feed is the largest cost in fish farming. One obstacle to economical diets for HSB is a lack of data on nutrient digestibility from different feedstuffs. Experiments conducted at the H.K.D. Stuttgart National Aquaculture Research Center determined the availability of protein and individual amino acids - the building blocks of protein in feedstuffs for HSB. Three tested ingredients were by-products of meat processing. Four ingredients were commercial blends of meat by-products. Three ingredients were common plant crops, and one ingredient was a by-product of the brewing industry. Nutritionally complete diets containing a test ingredient were extruded like those fed on fish farms. Tanks of HSB were fed the diets for several days and feces were collected and analyzed to determine the amount of nutrients the fish digested. The amount of protein digested from fish solubles (a processing waste) was highest at 70%. Protein in blood meal and poultry by-product was also well digested at 63% and 55%. The digestibility of protein in the blended products ranged from 47% to 63%. About 43% protein in canola was digestible, 54% in Brewer's yeast, 69% in sunflower, and 80% of the protein in peanut meal. The availability of amino acids (AA's) in a given feedstuff did not always match its protein digestibility. For example, the availability of lysine, tyrosine, and phenylalanine in fish solubles (70% digestible protein) was low at 31%, 35%, and 44%, respectively. Among the tested animal and blended by-products, AA's in Pro-Pak 60 were most available. Amino acids in peanut meal were more available than those in the other plant products. These data will allow scientists and feed mills to formulate less expensive, yet nutritious, diets for HSB.
Technical Abstract: A pair of experiments was conducted to determine protein digestibility and amino acid availability to sunshine bass from commercially available animal protein feedstuffs, blended animal by-products and plant protein feedstuffs in extruded diets. The feedstuffs tested were blood meal, poultry by-product meal, fish solubles, Pro-Pak 60, Pro-Pak 65, ProCon 65RDB, and 60FMC for the animal protein feedstuffs and brewer's yeast, canola meal, peanut meal, and sunflower meal for the plant protein feedstuffs. Test diets consisted of a mixture of nutritionally complete reference diet and test ingredient. Triplicate tanks of fish were fed either reference and test diets for seven days prior to collection of feces by stripping. Apparent digestibility coefficients of protein (ADC-CP) in the animal products ranged from 47% for 60FMC to a high of 70% for fish solubles. Blood meal, poultry by-product meal, Pro-Pak 60, Pro-Pak 65, and ProCon had intermediate ADC-CPs of 63, 55, 63, 57, and 52%, respectively. ADC-CP for the protein in plant feedstuffs ranged from 43% for canola meal to 80% for peanut meal. Brewer's yeast, canola meal, and sunflower meal had intermediate ADC-CPs at 54, 43, and 69%, respectively. Apparent amino acid availability coefficients were variable across animal products and did not necessarily correlate to the ADC-CPs for a given feedstuff. Isoleucine availability was low in blood meal at 38% compared to 59% or better for the remaining amino acids. Lysine, tyrosine and phenylalanine availability from fish solubles was low at 31, 35, and 44%, respectively. Amino acid availability from Pro-Pak 60 was consistently higher across all amino acids for the animal products and blends tested. Of the plant products tested, peanut meal was the best performing feedstuff relative to amino acid availability.