Effects of Graded Levels of Carbohydrate on Growth and Survival of Largemouth Bass, Micropterus salmoides

Excessive carbohydrates (CHO) in diets for largemouth bass (LMB), Micropterus salmoides, are suspected of accumulating glycogen in hepatocytes, which may result in liver dysfunction. This study evaluated the effect of graded levels of dietary CHO on growth, survival, and liver histology of LMB. One hundred feed‐trained advanced fingerling LMB (128.5 ± 21.5 g) were stocked into each of nine 3400 ‐ L polyethylene tanks. Tanks were randomly assigned one of three experimental diets containing different CHO levels (13, 19, or 25% of diet). The extruded diets were approximately isonitrogenous (42% crude protein) and isocaloric (3 kcal/g energy). There were three replicate tanks per dietary treatment. Bass were fed to apparent satiation twice daily for 148 d. Survival was significantly higher (P ≤ 0.05) for fish fed the 13 and 19% CHO diets (89 and 90%, respectively) compared to those fed the 25% CHO diets (82%). Average harvest weight of fish fed the 13% CHO diet (380 g) was significantly greater (P ≤ 0.05) than for fish fed other diets. Average harvest weight of fish fed the 19% CHO diet (347 g) was significantly greater (P ≤ 0.05) than for fish fed the 25% CHO diet (310 g). Specific growth rates (%/d) were significantly higher (P ≤ 0.05) in fish fed the 13 and 19% CHO diets than in fish fed 25% CHO diet. Feed conversion ratios for fish fed the 13 and 19% CHO diets (2.3 and 2.4, respectively) were both significantly lower (P ≤ 0.05) than in fish fed the 25% CHO diet (3.6). There were no significant differences (P > 0.05) in condition factor, protein efficiency ratio, hepatosomatic index, or liver glycogen concentration among fish fed the different experimental diets. Overall, mean blood glucose levels in fish fed the 13 and 19% CHO diets (61.0 and 71.2 mg/dL, respectively) were significantly lower (P ≤ 0.05) than in fish fed the 25% CHO diet (87 mg/dL). Histopathological examination of livers from fish fed the three diets was used to score the degree of vacuolization of hepatic tissues (0 = normal, 1 = slight, 2 = mild, 3 = moderate, and 4 = severe). Regression of vacuolization scores on dietary CHO levels was statistically significant (P ≤ 0.05) and indicated a direct positive relationship between liver vacuolization and dietary CHO level (R² = 0.57). These data indicate that LMB grow faster and use feeds more efficiently when CHO are maintained at <20% of diet. CHO levels >20% negatively impacted liver histology, but a liver tissue analyses did not document glycogen accumulation.     

ULTRASONOGRAPHY OF GASTRIC ULCERATION IN THE DOG

The clinical, ultrasonographic and, when available, histopathologic findings of gastric ulceration in 7 dogs were reviewed. The most common clinical signs were vomiting, hematemesis, melena, weight loss and anemia. Ultrasonographic features of gastric ulcer included local thickening of the gastric wall, possible loss of the 5-layer structure, the presence of a wall defect or "crater", fluid accumulation in the stomach and diminished gastric motility.The localized gastric thickening varied from 9 to 16 mm. The ulcer crater was often located in the center of the thickened site and appeared as a mucosal defect associated with persistent accumulation of small echoes, most likely representing microbubbles. In this preliminary study, there was no definitive ultrasonographic distinction between benign and malignant ulcers.     

In vitro activity of dicationic compounds against a North American foxhound isolate of Leishmania infantum

Canine leishmaniasis caused by Leishmania infantum is enzootic in the North American foxhound population. Currently available chemotherapy for canine leishmaniasis is not completely effective and relapses are common in treated dogs. Pentamidine and related aromatic diamidines possess broad spectrum antiprotozoal activity. The in vitro antileishmanial activities of 35 aromatic cationic molecules were determined, using pentamidine as the reference drug. The compounds were examined for activity against promastigotes of L. infantum isolated from a foxhound from Virginia. The compounds most active against Leishmania parasites were reversed amidines. Compound 9, a reversed amidine, exhibited the highest activity against L. infantum, with a 50% inhibitory concentration (IC(50)) of 0.0042 microM compared with 14.2 microM for pentamidine. Antileishmanial activities of nine compounds were at least 1000-fold higher relative to the reference drug. Results from this study indicate that several pentamidine-related compounds warrant further investigation as possible new agents for the treatment of canine leishmaniasis.     

Production Response of Freshwater Prawns Macrobrachium rosenbergii to Increasing Amounts of Artificial Substrate in Ponds

Abstract.— The response of freshwater prawns Macrobrachium rosenbergii to increasing amounts of artificial substrate was evaluated in ponds. Juvenile prawns (0.24 ± 0.13 g) were stocked into nine 0.04-ha ponds at 74,000/ha. Three control ponds received no artificial substrate while artificial substrate in the form of horizontal strips of polyethylene construction fence was added to the six treatment ponds to produce 40% or 80% increases in available surface area. Increasing availability of surface area produced a direct linear increase ( P < 0.05, r ²= 0.89) in total production with no significant change in average weight ( P > 0.05). There was an inverse linear relationship between available surface area and feed conversion ratios ( P < 0.01, r ² = 0.66) likely indicating increased availability of natural foods or reduced stress among animals. There was a direct linear increase in the percentage of females which achieved sexual maturity ( P < 0.01, r ²= 0.71) as the amount of added substrate was increased. Size and number of other sexual morphotypes were not significantly affected. These responses are consistent with those that would be expected if stocking densities were decreased. These data indicate that prawn production increases in direct relation to the amount of added substrate while utilizing feed more efficiently. The effect of substrate orientation on its functionality should be evaluated to allow further increases in substrate inclusion amounts for additional production intensification.     

Evaluation of growth, feed utilization, and economics of hybrid tilapia, Oreochromis niloticus×Oreochromis aureus, fed diets containing different protein sources in combination with distillers dried grains with solubles

A feeding trial was conducted in aquaria with juvenile hybrid tilapia (Oreochromis niloticus×Oreochromis aureus) to evaluate the use of different protein sources in combination with distillers dried grains with solubles (DDGS). Twelve 110‐L glass aquaria were stocked with 28 juvenile (2.7±0.5‐g) hybrid tilapia per aquarium. Three replicate aquaria were randomly assigned to each of the four dietary treatments. Diets were isonitrogenous and isocaloric. The control diet contained 12% fish meal and 41% soybean meal as the primary protein sources (Diet 1). Each experimental diet contained 30% DDGS by weight, in combination with 8% fish meal and 34% soybean meal (Diet 2), 26% meat and bone meal (MBM), and 16% soybean meal (Diet 3), or 46% soybean meal alone (Diet 4). Fish were fed to apparent satiation twice a day for 10 weeks. There were no significant differences (P>0.05) in average weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) among tilapia fed Diets 1, 2, and 3. Fish fed Diet 4 had significantly lower (P<0.05) average weight gain, SGR, and PER than fish fed Diets 1 and 3. Relative cost per unit weight gain for Diets 1, 2, and 3 were statistically similar (P>0.05), while cost per unit weight gain for Diet 4 was significantly higher (P<0.05) than other diets. Diet 3 represented approximately a 20% cost savings compared with the control diet, with no reduction in growth. This study indicates that diets without fish meal containing 30% DDGS in combination with MBM and soybean meal provide good growth in tilapia. A diet without animal protein did not support acceptable growth.     

Nutritional evaluation of an improved soybean meal as a fishmeal replacer in the diet of Pacific white shrimp,Litopenaeus vannamei

A 12‐week growth trial was conducted to assess an improved soybean meal (ISBM) in the diet of Pacific white shrimp (PWS). Four isonitrogenous and isolipidic experimental diets were formulated: the control diet (ISBM‐0) contained 30% fishmeal (FM) and three test diets (ISBM‐33, ISBM‐66 and ISBM‐100) were formulated by gradually replacing FM on an isonitrogenous basis. Groups of PWS (3.2 g mean initial weight) were fed their respective experimental diets three times per day. Production performance of PWS was unaffected by diet, except the final weight of shrimp‐fed ISBM‐66 diet was significantly lower than those fed ISBM‐0. Whole‐body moisture was significantly higher and protein was significantly lower in PWS‐fed ISBM‐100 versus shrimp‐fed ISBM‐0. PWS‐fed ISBM‐66 had significantly higher oleic acid than shrimp‐fed ISBM‐0 and linolenic acid versus shrimp‐fed ISBM‐0 and ISBM‐100. The lowest linoleic acid and n‐6 polyunsaturated fatty acids levels were found in shrimp‐fed ISBM‐100. Based on second‐degree polynomial regression analysis of final weight and weight gain, the estimated optimum levels of ISBM to replace FM in PWS diets are 89.13% and 95.56% respectively. Overall, results indicate alternative, sustainable, plant‐based protein sources such as ISBM may potentially replace FM in PWS diets.     

Cross-sectional imaging techniques in veterinary ophthalmology

Ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) are useful, complementary cross-sectional imaging modalities of the eye and orbit. High-resolution US provides excellent morphological information of ocular structures but offers limited information on the periocular tissues. CT and MRI provide valuable morphologic and topographic images of both ocular and periocular structures, thereby giving a more complete picture of the pathological process. US can be performed on awake patients, whereas CT and MRI require general anesthesia. In addition, US equipment is readily available and less costly than CT or MRI units. Fine-needle aspirations and biopsies under US or CT guidance can also be performed. This article reviews the technique and normal findings of ocular and orbital structures as displayed in each of these imaging modalities. Representative clinical cases are presented to illustrate the interpretation principles as well as to provide an illustrative reference for common ocular and orbital changes.     

Total replacement of fish meal by soy bean meal, with various percentages of supplemental L-methionine, in diets for blue catfish, Ictalurus furcatus (Lesueur)

A 12-week feeding trial was conducted in aquaria with juvenile (8.9 g) blue catfish, Ictalurus furcatus (Lesueur), to examine effects of totally replacing fish meal with a high (65%) percentage of soy bean meal (SBM) in prepared diets. Five isonitrogenous (35% protein) and isocaloric (10.5 kJ digestible energy g^?1 of diet) diets were formulated. Diet 1 was similar to a high-quality commercial channel catfish diet, containing 15% fish meal and 42% SBM. Diets 2-5 contained 0% fish meal and 70% SBM with various amounts (0.0%. 0.3%, 0.6% and 0.9%) of L-methionine added. After 12 weeks, individual weight, weight gain, survival, specific growth rate, feed conversion ratio, protein efficiency ratio and food intake were not significantly different (P > 0.05) among treatments and averaged 36 g, 302%, 100%, 1.6% day^?1. 2.4,1.3, and 3.4% body weight, respectively. Whole-body compositions of fish were not significantly different (P > 0.05) among treatments and averaged 75%, 61% and 27% for percentage moisture, protein and fat, respectively. These data suggest that a diet with an all-plant protein source (SBM) can totally replace fish meal in a diet for blue catfish, without adverse affects on weight gain or body composition, when the dietary protein level is 35% and fish are fed to satiation.