A study was conducted to examine the use of corn distillers’ by‐products in diets and the effects of additional dietary fat on channel catfish, Ictalurus punctatus, performance. Juvenile channel catfish (initial weight: 12.6 g per fish) were stocked in flow‐through aquaria and fed one of six practical diets for 9 weeks. Fish fed the control + fat diet consumed more diet and had higher feed efficiency ratio (FER) than fish fed the control diet, but weight gain was not significantly different between fish fed these two diets. Fish fed the diet containing 300 g kg−1 distillers dried grains with solubles (DDGS) consumed more diet and gained more weight, but had similar FER compared with fish fed the control + fat diet. The diet containing 200 g kg−1 high‐protein distillers grains (HPDDG) resulted in similar diet consumption, weight gain and FER as the control + fat diet. Fish fed the diet containing 100 g kg−1 distillers solubles (DS) consumed more diet, but had similar weight gain and FER compared with fish fed the 300 g kg−1 DDGS diet. The presence of distillers solubles in the diet (300 g kg−1 DDGS, 100 g kg−1 DS, 100 g kg−1 EDS diets) appears to increase diet consumption, weight gain, and FER over the control diets with or without additional fat.

A study was conducted with channel catfish, Ictalurus puntatus to determine apparent digestibility/availability coefficients of protein, amino acids, lipid and energy for alternative plant-protein feedstuffs: corn gluten feed, corn germ meal, distillers dried grains with solubles, and canola meal, compared with those for soybean meal. A 32%-protein, chemically defined diet containing 8% fish meal was used as the reference diet. Test diets consisted of 70:30 ratio of reference diet to test ingredient with chromic oxide (0.75% of the diet) as an inert indicator. Apparent digestibility/availability coefficients of protein, essential amino acids and energy in alternative protein feedstuffs tested were generally lower than those in soybean meal by channel catfish. Apparent digestibility coefficients of protein ranged from 75 to 87% and those of energy ranged from 52 to 59% for alternative feedstuffs. Lysine in alternative feedstuffs was 67-79%, methionine was 69-85% and cystine was 73-82% available to channel catfish. There were no significant differences in lipid ADCs among test feedstuffs (91.9-96.8%). Results from the present study can be useful in formulating cost-effective catfish feeds using these alternative feedstuffs.

The prices of soybean meal and corn—the two most commonly used, traditional feed ingredients in channel catfish diets—have increased dramatically in recent years. Using less‐expensive alternative feed ingredients to partially replace soybean meal and corn would reduce feed cost. The present study evaluated the use of corn gluten feed and cottonseed meal, two promising alternative feedstuffs, as replacements for soybean meal and corn in diets for pond‐raised channel catfish Ictalurus punctatus. Five isonitrogenous (28% crude protein) diets that used corn gluten feed and cottonseed meal (approximately 1:1 ratio) to replace 0, 25, 50, 75, or 100% of the soybean meal in the control diet were evaluated. The level of corn in the diet decreased as those of corn gluten feed and cottonseed meal increased. Stocker‐size channel catfish (mean initial weight = 0.175 kg/fish) were stocked into twenty 0.05‐ha earthen ponds at a rate of 14,830 fish/ha. Fish were fed once daily to apparent satiation over a growing season. Net yield, carcass and fillet yield, and fillet protein and fat levels decreased and the feed conversion ratio increased linearly as soybean meal replacement levels increased. These results demonstrate that a maximum of 50% of the soybean meal in channel catfish diets may be replaced (soybean meal was reduced from 51.4% to 25.7%) by a combination of corn gluten feed and cottonseed meal (up to 20% of each in the diet) without markedly affecting the physical quality of feed pellets, fish growth, processed yield, and body composition. The poor performance of diets containing high levels of corn gluten feed and cottonseed meal are probably a result of high fiber, low digestible energy, or both.Received June 1, 2010; accepted October 1, 2010

This study examined the use of corn gluten feed (CGF) and cottonseed meal (CSM) to partially replace soybean meal and corn in diets for pond‐raised hybrid catfish, Ictalurus punctatus×I. furcatus. Five 28% protein diets containing various combinations of CGF and CSM were evaluated. Fingerling hybrid catfish (mean initial weight: 45 g/fish) were stocked into 25, 0.04‐ha ponds at a rate of 14,826 fish/ha. Fish were fed once daily to apparent satiation for a 179‐d growing season. CGF at 30% of the diet (10% CSM) and a combination of CGF and CSM up to 25% each did not affect physical quality (percentages floatability and feed dust) of the diet. No significant differences were observed in total amount of diet fed, net yield, diet consumption, weight gain, feed conversion ratio (FCR), survival, and fillet proximate nutrient composition among fish fed various diets. Results show that hybrid catfish can utilize CGF at levels up to 30% of the diet (10% CSM), and a combination of CGF and CSM up to 25% each without significantly affecting growth, diet consumption, FCR, and fillet proximate nutrient composition. However, a combination of CGF and CSM at 20% each and above reduced carcass yield.

A study was conducted to examine the use of distillers grains with solubles (DDGS), ethanol extracted DDGS (EDDGS), and brewers yeast in channel cat¢sh, Ictalurus punctatus, diets. Diets containing these ingredients were compared with all-plant and ¢sh meal control diets. Juvenile channel cat¢sh (initial weight: 9.1 AE 0.2 g ¢sh À 1 ) were stocked in £ow-through aquaria and fed one of six practical diets for 8 weeks. Diets containing1% brewers yeast or 30% DDGS supported the same level of growth and feed e⁄ciency ratio (FER) as the diet containing 5% ¢sh meal. Ethanol extraction e¡ectively removed most of the fat and yellow pigments in DDGS. The diet containing 30% EDDGS resulted in signi¢cantly lower growth and FER compared with the diet containing DDGS. However, the weight gain of ¢sh fed the EDDGS diet was intermediate compared with ¢sh fed the all-plant control, ¢sh meal control, and 1% and 2% brewers yeast diets. The EDDGS could potentially be used at high levels as a substitution for soybean meal without causing yellow pigment deposition in cat¢sh £esh, provided that the ethanol extraction process is proven economical. Brewers yeast, used at 1^2% of the diet, appears to be e¡ective at improving weight gain and FER of channel cat¢sh over the all-plant diet.