Growth and feed utilization of gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>, L.) fed to satiation and restrictively at increasing dietary energy levels

Three isoproteic (47% protein) diets were formulated to contain graded levels of crude fat (diet D16:16%, diet D24: 24% and diet D32: 32%). Each diet was fed to satiation in three and to 80% satiation in two replicate groups of gilthead sea bream (Sparus aurata), having an initial body weight of 72–74 g. The trial lasted 81 days. Groups fed to satiation showed higher final body weight (FBW; 238.8–252.3 g vs. 218.0–229.3 g) and daily growth index (DGI; 2.49–2.65%/day vs. 2.27–2.34%/day) than those fed to 80% satiation. Feed intake was significantly different both for feeding level and for diet composition. Fish fed to satiation had higher feed conversion rate (FCR) compared to the 80% satiation groups (1.33–1.44 vs. 1.13–1.17; P ≤ 0.001). Within satiation groups, FCR was significantly lower in fish fed D16 compared to fish fed D32 (1.33 vs. 1.44, P ≤ 0.05), whereas no statistical differences were found within the 80% satiation groups. The increase in dietary lipid level did not improve growth performance, feed efficiency and protein utilization but decreased gross lipid efficiency. Conversely, a reduction in ration from satiation to 80% satiation decreased DGI, thus improving FCR. Feed costs were influenced by dietary energy level and feeding ratio, the lowest energy diet at 80% satiation being the most profitable combination among the variables.     

The influence of different levels of dietary vitamin E on sea bass Dicentrarchus labrax flesh quality

Sea bass Dicentrarchus labrax fillet quality was investigated after feeding with four diets (A, B, C or D) containing different levels of dietary vitamin E (139 mg kg^–1, 254 mg kg^–1, 493 mg kg^–1 and 942 mg kg^–1, respectively). Six-hundred and eighty fish (mean initial weight 208 g) were equally divided into four 20 m³ tanks and fed for 87 days. Filtered seawater with a temperature ranging from 18.2 to 26.3 °C was supplied continuously. At the end of the experiment, fish were stored at 1 °C for 12 days. At one, three, six, nine and 12 days, 20 fish per group were processed for proximate composition, vitamin E and induced thiobarbituric acid reactive substances (TBARs) analyses. No significant differences in proximate composition were registered between groups. The flesh lipid content ranged from 88.0 g kg^–1 (group B) to 96.8 g kg^–1 (group A). Vitamin E fillet content was significantly different between groups, reaching levels of 98.0, 150.7, 225.2 and 302.0 μg g^–1 lipids for group A, B, C and D, respectively. Induced TBARs values were statistically different only for group A compared with the other groups. No significant variations were registered in relation to preservation time. Because of the positive influence of vitamin E on seafood quality and the correlation between its dietary level and flesh deposition, the α-tocopherol content of the diet should be well above fish minimum requirements.     

Effect of prolonged branched-chain amino acid supplementation on metabolic response to anaerobic exercise in standardbreds

This study investigated the effect of prolonged BCAA supplementation on metabolic response to a 1600m run on treadmill in Standardbred trotters. Four trained Standardbreds were divided into two groups and assigned in a 2×2 Latin square design. Both groups were fed and exercised similarly: one group received an oral amino acids supplement (12 g leucine, 9 g isoleucine and 9 g valine) 30 minutes prior to exercise and immediately after, the other group received a placebo. The horses received the supplement 3 days per week for 5 weeks. In the last week horses performed an anaerobic exercise test on an inclined (3.5%) high-speed treadmill. The exercise consisted of a 15 minute warm-up phase immediately followed by a 1600 m run at maximal speed (heart rate > 200 beats/min). Blood samples were collected pre-exercise, after exercise and during recovery (10 min, 30 min, and 24 h), and analyzed for lactate, ammonia, total protein, urea, uric acid, creatinine, free fatty acids (FFA), creatine kinase (CK), lactate dehydrogenase (LDH), aspartate amino transferase (AST). Heart rate was continuously recorded during exercise and recovery. No statistical differences between the groups were observed for all the considered parameters. Nevertheless, BCAA supplementation resulted in a higher plasma ammonia and urea concentrations as reported in previous studies in humans and rats. These data suggest that a BCAA supplementation are not effective in enhancing performance in healthy and well-fed horses.     

Application of a constant blood withdrawal method in equine exercise physiology studies.

The aim of the present study was to test a constant blood withdrawal method (CBWM) to collect blood samples from horses during treadmill exercise. CBWM was performed in 4 Standardbreds and 5 Haflinger horses. A peristaltic pump was used to control blood aspiration from an i.v. catheter via an extension line. Blood was collected using an automatic fractions collector, with a constant delay time between the drawing of blood and sample collection. Blood withdrawal using CBWM was made during a treadmill standardised exercise test (SET). A blood flow of 12 m/min was used and samples collected every 60 s during the entire period of exercise. The volume of blood collected in each sample tube was 12.1+/-0.2 ml, with a delay time of mean +/- s.d. 25.3+/-0.8 s. Plasma lactate kinetics based on measurement of lactate in each fraction showed an exponential increase during the first 13 min of exercise (10.5 min of SET and 2.5 min recovery). The peak plasma lactate concentration was observed between 2.5 and 5.5 min after the end of SET. CBWM permits the kinetics of lactate and other blood-borne variables to be studied over time. This method could be a valuable aid for use in studying equine exercise physiology.     

Intestinal metabolism of weaned piglets fed a typical United States or European diet with or without supplementation of tributyrin and lactitol

The aim of the study was to investigate the effects of supplementation of a microencapsulated blend of tributyrin and lactitol (TL) to a standard European (EU) diet without antibiotic growth promoters on intestinal metabolism and mucosa development of weaned piglets and to compare it with a standard US diet containing animal proteins, zinc oxide, copper sulfate, and carbadox. Ninety piglets weaned at 21 d were divided into 3 dietary groups consisting of 5 replicates each: 1) US diet supplemented with 55 mg/kg of carbadox, and 2.5% each of plasma proteins and spray-dried blood cells in the first phase, 3,055 mg/kg of Zn in the first and second phases, and 180 mg/kg of Cu in the third phase; 2) EU diet based on vegetable proteins and no antibiotics; and 3) the same EU diet supplemented with 3,000 mg/kg of microencapsulated TL. The study was divided into 3 phases: 0 to 7, 8 to 21, and 22 to 35 d. On d 7, 21, and 35, animals were weighed, and feed consumption and efficiency were determined. On d 14 and 35, one pig per pen was killed, and the intestinal contents and mucosa from the proximal, middle, distal jejunum and the ileum were sampled. Intestinal wall sections were fixed for histological analysis, and intestinal content was used for VFA, ammonia, and polyamine analysis. Throughout the study (d 0 to 35), the US diet had greater ADG and ADFI than the EU diet (P < 0.05). The EU diet supplemented with TL tended to have 11% greater ADG (P = 0.17). Feeding the EU diet caused a reduction in proximal and middle jejunum villi length by 10% (P < 0.05) and an increase in crypt size in proximal jejunum (P < 0.05) compared with the US diet, probably due to an increased rate of cell loss and crypt cell production. The TL supplementation resulted in longer villi along the jejunum and less deep crypts in the proximal jejunum (+15.9 and -8.9%, respectively; P < 0.05) than the unsupplemented EU diet. The TL diet increased the concentrations of cadaverine and putrescine in the small intestine (P < 0.05) and seemed to increase cadaverine, histamine, putrescine, and spermine in the large intestine by 1.5- to 10-fold compared with the US or EU diet. In conclusion, although the US diet had a greater effect on growth performance and mucosal trophic status than the EU diets, the supplementation with slowly released TL seemed to be an effective tool to partially overcome the adverse effects of vegetable protein diets.     

Enteroendocrine profile of α-transducin immunoreactive cells in the gastrointestinal tract of the European sea bass (Dicentrarchus labrax)

In vertebrates, chemosensitivity of nutrients occurs through the activation of taste receptors coupled with G-protein subunits, including α-transducin (G_αtran) and α-gustducin (G_αgust). This study was aimed at characterising the cells expressing G_αtran immunoreactivity throughout the mucosa of the sea bass gastrointestinal tract. G_αtran immunoreactive cells were mainly found in the stomach, and a lower number of immunopositive cells were detected in the intestine. Some G_αtran immunoreactive cells in the stomach contained G_αgust immunoreactivity. Gastric G_αtran immunoreactive cells co-expressed ghrelin, obestatin and 5-hydroxytryptamine immunoreactivity. In contrast, G_αtran immunopositive cells did not contain somatostatin, gastrin/cholecystokinin, glucagon-like peptide-1, substance P or calcitonin gene-related peptide immunoreactivity in any investigated segments of the sea bass gastrointestinal tract. Specificity of G_αtran and G_αgust antisera was determined by Western blot analysis, which identified two bands at the theoretical molecular weight of ~45 and ~40 kDa, respectively, in sea bass gut tissue as well as in positive tissue, and by immunoblocking with the respective peptide, which prevented immunostaining. The results of the present study provide a molecular and morphological basis for a role of taste-related molecules in chemosensing in the sea bass gastrointestinal tract.     

Digestive enzyme inhibitors and storage pest resistance in cowpea (Vigna unguiculata) seeds

Summary Amylase and trypsin inhibitors are proteins which inhibit digestive enzymes. The loss of the activity of these enzymes produces a reduction of starch and protein digestion. Amylase and trypsin inhibitor activity have been investigated in seeds of 20 cowpea lines in trying to establish their role in the storage pest resistance. A broad variation has been observed for both the inhibitors. Correlation analysis between inhibitor levels and extent of attack has shown that neither amylase nor trypsin inhibitors can separately explain the resistance to Callosobruchus maculatus (F.). Lines bruchid resistant in fact, have high levels of both inhibitors. Conversely lines with low levels of amylase and trypsin inhibitors are bruchid susceptible. The breeding for high contents of both amylase and trypsin inhibitors can be an effective way to obtain lines with resistance to storage pest.     

Enzyme polymorphism in faba bean (Vicia faba L. minor) accessions. Genetic interpretation and value for classification

Three isozyme sytems glutamate oxaloacetate transaminase (GOT), superoxide dismutase (SOD), and malic enzyme (ME) have been analysed electrophoretically to study the diversity within and between 33 faba bean (V. faba L. type minor) accessions. For comparison, two cultivars (Vesuvio and Talo) were included in the study. Further objective of this study was to classify populations into genetic similar groups. SOD and GOT showed large variation, while ME presented minor change. Principal components, hierarchical cluster, and canonical discriminant analyses produced five groups with significant differences among them. The alleles with low frequency played a significant role in the discrimination. It was concluded that more detailed investigations regarding genetic aspects of enzyme diversity are needed to support the data here reported. This revised version was published online in July 2006 with corrections to the Cover Date.