Edwin H. Robinson

Protein and energy requirements of juvenile red drum (Sciaenops ocellatus)

Abstract Two studies were conducted to evaluate the effects of different dietary levels of protein and energy on growth and body composition of juvenile red drum ( Sciaenops ocellatus ) grown in a low salinity environment. In each experiment, increased dietary energy resulted in decreased growth, protein efficiency ratio, protein retention, and feed utilization. Whole body lipid tended to increase with increasing dietary lipid. Data from experiment 1 indicated that 35% protein and 1.70 × 10 4 kJ/g were adequate for good growth and high quality body composition (i.e., low fat and high protein) in red drum reared at 22–26°C. Red drum in the second study, reared at 26–33°C, grew best when fed to satiation on a 44% protein diet at dietary energy levels of 1.54 × 10 4 and 1.72 × 10 4 kJ/g. In addition, higher levels of dietary carbohydrate and lipid were associated with an increased hepatosomatic index.

Dietary calcium and phosphorus requirements of Oreochromis aureus reared in calcium-free water

Abstract Two experiments were conducted to evaluate the dietary calcium and phosphorus requirements of fingerling Oreochromis aureus reared in calcium-free water. A casein basal diet was supplemented with graded levels of either calcium or phosphorus and fed for 12 weeks. Dietary calcium concentrations ranged from 0.17 to 1.00% and dietary phosphorus concentrations ranged from 0.20 to 1.00%. Weight gain and feed conversion data indicated that 0.70% dietary calcium was optimum for good growth. Whole-body, bone or scale minerals did not clearly reflect the calcium requirement as established by growth. Weight gain and feed conversion data indicated that 0.30% dietary phosphorus was adequate for good growth. However, bone ash, phosphorus, and calcium data indicated that 0.50% dietary phosphorus was required for normal bone mineralization.

Response of red drum to various dietary levels of menhaden oil

A study was conducted to evaluate the effects of feeding, varying levels of menhaden oil on weight gain, feed conversion, and whole-body proximate and fatty acid composition of red drum. The experiment was conducted utilizing a brackishwater (5–6 ppt) recirculating system which supplied water to a series of 40-l aquaria. Fish (1.8g) were stocked at a rate of 12 fish per aquarium (48 fish/treatment) and fed the appropriate diet twice a day for a period of 6 weeks. All diets contained 40% protein and an estimated digestible energy value of 15.4 kJ/g of diet. Dietary lipid levels ranged from 1.7 to 18.8%. Weight gain, feed conversion, and survival were best at dietary lipid levels of 7.4 and 11.2%. Fish fed the diet containing 18.8% lipid had lower weight gains and higher feed conversion ratios than fish fed lower levels of lipid. Whole-body lipid concentrations increased as dietary lipid increased up to 7.4% then decreased when dietary levels were elevated to 15% or greater. Whole-body fatty acids generally reflected dietary lipid, particularly in respect to the n3 polyunsaturated fatty acids.

Dietary calcium requirement of channel catfish Ictalurus punctatus, reared in calcium-free water

Abstract Two experiments were conducted to determine the dietary calcium requirement of fingerling channel catfish reared in calcium-free water. Triplicate random groups of fish were fed purified diets containing graded levels of calcium ranging from 0.17 to 0.85%. All diets contained 0.5% phosphorus. Feed was offered for a period of 11 or 12 weeks. Growth and feed efficiency indicated that the dietary calcium requirement for channel catfish, reared in calcium-free water, was approximately 0.45% of the dry diet. Vertebral bone calcium, phosphorus and ash remained relatively constant at all dietary calcium levels. Based on these data, it appears that channel catfish conserve bone calcium during periods of calcium inadequacy. Serum calcium did not reflect the requirement level as determined by growth.

Effects of feeding glandless or glanded cottonseed products and gossypol to Tilapia aurea

Abstract Seven isocaloric and isonitrogenous practical diets in which either glanded or glandless cottonseed products were substituted for soybean and/or peanut meals, and three purified diets containing graded levels of gossypol were fed to fingerling Tilapia aurea for a period of 10 weeks. Growth, feed conversion and survival data indicated that glanded and glandless cottonseed products were not as high in nutritive value for tilapia as are soybean and peanut meals. The inferior performance of fish fed cottonseed protein did not appear to be related to dietary gossypol. Carcass fatty acids generally reflected dietary fatty acids. An increase in palmitic and linoleic fatty acids was observed in fish fed fullfat, glandless cottonseed flour.

An estimate of the dietary calcium requirement of fingerling Tilapia aurea reared in calcium-free water

Abstract Seven isocaloric and isonitrogenous semi-purified diets which contained graded levels of calcium ranging from 0.17 to 3.20% were fed to fingerling Tilapia aurea for a period of 11 weeks. The fish were maintained in a flow-through aquarium system supplied with calcium-free well water. Growth, feed conversion and bone composition data indicated that between 0.17 and 0.65% dietary calcium was adequate for optimum growth and normal bone mineralization.

Optimum Ratio of Dietary Protein to Energy for Red Crayfish (Procambarus clarkii)

Abstract Six experimental diets were formulated with protein-to-energy (P:E) ratios ranging from 57 to 160 mg protein/kcal. The diets, which were fed to juvenile red crayfish, contained either 20, 30, or 40% crude protein and 2.5 or 3.5 kcal of total energy per gram of diet. As dietary energy increased, growth of crayfish fed the 30% protein diets decreased, but growth of crayfish fed the 40% protein high-energy diets increased. In general, the percentage of body protein (wet weight) decreased as dietary energy increased. Crayfish fed low-energy (low-fat) diets had lower percentages of body fat. Also, body fat tended to decrease as dietary protein increased. Best growth and protein deposition were observed in crayfish fed a diet with a P:E ratio of 120 mg protein/kcal; this diet contained 30% crude protein and 2.5 kcal/g dietary energy.

Evaluation of Glanded and Glandless Cottonseed Products in Catfish Diets

Abstract Seven isocaloric and isonitrogenous diets in which either glanded or glandless cottonseed products were substituted for soybean and/or peanut meals, were fed to age-0 channel catfish Ictalurus punctatus for a period of 10 weeks. All diets were supplemented with lysine HCl. Based on growth, feed conversion and survival data defatted, glandless cottonseed flour supplemented with lysine appears to be an adequate protein for use in channel catfish diets. Growth of fish fed either glanded cottonseed meal or fullfat, glandless cottonseed flour was depressed when compared to fish fed defatted, glandless cottonseed flour as the sole plant protein source. Whole body fatty acid patterns reflected dietary fat composition.

Vitamin D studies with channel catfish (Ictalurus punctatus) reared in calcium-free water

Abstract 1. 1. Various levels and forms of vitamin D were fed to channel catfish (Ictalurus punctatus) in rearing water containing 0.0 mg/1 calcium; an experimental system in which fish must rely on a dietary source of calcium. 2. 2. Based on weight gain data, the dietary requirement for vitamin D from these studies appeared to be 250–500 I.U./kg as either cholecalciferol or ergocalciferol. 3. 3. Plasma K, 25-OHD, and 24,25-(OH)2D levels indicated a dietary requirement of 20001.U./kg as cholecalciferol. 4. 4. The discrimination in use of relatively high levels of ergocalciferol appeared to be related to further hydroxylation of the 25-hydroxymetabolite. 5. 5. Effects on calcium and phosphorus levels were not affected by levels or form of the vitamin and emphasize the differences between aquatic and terrestrial vertebrates.

Comparison of Practical Catfish Feeds Containing 26 or 30% Protein

Abstract Channel catfish (Ictalurus punctatus) were grown in 0.04-hectare earthen ponds and fed practical diets containing either 26 or 30% crude protein. Experimental diets were formulated to contain similar protein : energy ratios, the proper levels of essential amino acids, and a minimal amount of fish meal. Fish were stocked at a density of 7,413 fish!hectare and fed for 119 d at rates that gradually declined from 5% of body weight per day. Weight gain, survival, feed conversion ratio, dressout percentage, and proximate composition of edible tissue were not significantly different between dietary treatment groups. Based on these results, it appears that a feed containing 26% protein from a combination of high-quality sources and having the proper protein: energy ratio is adequate for channel catfish reared in ponds at low to moderate densities.