A 10‐week growth trial was performed to evaluate the effects of feeding rate on growth performance, nutrient partitioning, and to determine the optimum feeding rate for young‐of‐the‐year white sturgeon. Three tanks with 30 fish per tank each were assigned to five feeding rates, 0.4–2.0% body weight per day (BW day?1). Weight gain significantly (P <0.05) increased with increasing feeding rate up to 1.2% BW day?1. Feed efficiency exhibited an inverse relationship to weight gain. Hepatosomatic and gonadal‐fat‐body (GFB)‐somatic indices were significantly affected by feeding rate, and the lowest values were observed at 0.4% BW day?1. The increased feeding rate significantly affected whole‐body and carcass lipid and moisture contents. Protein gain in the carcass, but not in the GFB, was significantly influenced by feeding rate. Lipid gain in the carcass and GFB was also significantly affected by feeding rate. Four regression models were tested for the estimation of optimum feeding rate, including one‐slope straight broken‐line, two‐slope straight broken‐line, quadratic broken‐line and quadratic models. Adjusted coefficient of correlation and corrected Akaike information criterion were used to compare model performance. The quadratic broken‐line model was chosen as the best based on the criteria. The estimated optimum feeding rate for young‐of‐the‐year white sturgeon (360 g) is 1.5% BW day?1. 相似文献
This study aimed to determine the effect of synbiotic (Biomin IMBO) as feed additive on beluga (Huso huso) juvenile with an average body weight of 26.45 ± 0.19 g. Experimental diets at which supplemented with 1.0, 2.0 and 4.0 g synbiotic per kg of feed were fed to beluga juvenile, whereas the control group was fed with no synbiotic. After the feeding trial for 8 weeks, growth performance, survival, lactobacillus bacterial count, blood indices and immunity were tested. Even though, some growth performance and feed utilization parameters including WG, SGR and FCR were improved in group fed with 2.0 g kg?1 synbiotic; however, there were no significant differences (P >0.05) in growth and feeding parameters between juveniles fed control and synbiotic supplementation diets. In terms of intestinal microbiota, there were no significant differences in total and lactic acid bacteria among treatments (P >0.05). In addition, there were no significant differences of RBC counts, haematocrit, monocyte, lymphocyte, neutrophil, serum glucose and serum total protein levels between the treatment groups (P >0.05), but group 2 and 4 g kg?1 synbiotic showed a significant difference (P <0.05) in WBC counts and haemoglobin, respectively. Furthermore, alternative complement activity (ACH50) and serum total immunoglobulin (Ig) were significantly increased in 2.0 g kg?1 synbiotic fed fish (P <0.05); however, it did not change the lysozyme activity, significantly (P >0.05). These results indicate that synbiotic improves immunity of beluga sturgeon without detrimentally impacting the growth performance, modulates intestinal microbiota and basic haematological parameters assessed. Thus, we suggest that 2.0 g kg?1 level of synbiotic may be used as an immunity promoter for beluga sturgeon juvenile. 相似文献
The present work describes the development by response surface methodology of a method for manganese and iron determination by flame atomic absorption spectrometry (FAAS) in cereal flours, which is based on microwave assisted extraction. The optimization process was performed using two level fractional factorial designs (24-1) and Doehlert design matrix. Four variables such as irradiation power, time, temperature and concentration of nitric acid were regarded as factors in the optimization. Results of two level fractional factorial designs with 10 runs for manganese and iron extraction, based on the Pareto chart, demonstrated that the factors irradiation power, time and temperature are statistically significant, and concentration of nitric acid is not significant. Then, a Doehlert design was carried out in order to determine the optimum conditions for the procedure through response surface study. The working conditions were established as a compromise between optimum values found for each analyte. These values were 87.0°C, 573.0 W and 40.0 min, for temperature, irradiation power and time, respectively. The accuracy of the optimized procedure was evaluated by analysis of certified reference material. The procedure proposed was applied for the determination of iron and manganese in cereal flours. 相似文献
An 8-week feeding trial was conducted to compare the effects of supplementing (0.7 mg kg?1) different dietary selenium (Se) sources including organic [selenomethionine (SeMet)], inorganic [sodium selenite (Na2SeO3)], and nanoparticulate Se (nano-Se) on physiological responses of common carp, Cyprinus carpio juveniles (9.7?±?0.1 g). Basal diet without Se supplementation used as control. Fish fed nano-Se supplemented diet had the highest weight gain (97.2?±?10.8%) and feed efficiency ratio (42.4?±?0.8%). Intestinal villi height was significantly taller in fish fed nano-Se diet than in the control group in both foregut and midgut sections. Serum glutathione peroxidase and superoxide dismutase activities were significantly higher in nano-Se and SeMet groups than in control and sodium selenite groups. Fish fed Se-supplemented diets had greater red blood cell counts and hematocrit and hemoglobin values than the control group (P?<?0.05). Nano-Se and SeMet groups showed a significant increase in white blood cell counts, neutrophil percentage, and serum lysozyme activity than the other groups. Fish fed nano-Se diet had the highest serum hemolytic activity, total immunoglobulin, and total protein and albumin contents, as well as the lowest serum total cholesterol and low density lipoprotein levels (P?<?0.05). Overall, significant improvements in growth performance, feed utilization, intestinal morphology, and hemato-immunological and serum biochemical parameters of common carp juveniles suggest nano-Se as an efficient source for providing dietary Se in this species. 相似文献
The effect of the dietary incorporation of drumstick, Moringa oleifera, leaf meal (MOL; 0, 5, 10 and 15%) on the growth, feed utilization, some skin mucus and systemic immune parameters and intestinal immune-related gene expression in gilthead seabream (Sparus aurata) specimens. The experiment lasted 4 weeks. The results revealed that MOL can be incorporated in S. aurata diet up to 10% with no significant negative effect on growth and feed utilization. However, there was a significant decrease with MOL at a level of 15% after 2 weeks of feeding. The systemic immune status of fish fed with the different levels of MOL showed an improvement in head kidney leucocyte phagocytosis, respiratory burst and peroxidase activities. Also, serum humoral components, including protease, ACH50 and lysozyme activities and IgM level, increased with MOL inclusion especially at the 5% level. MOL at 5% improved skin-mucosal immunity such as protease, antiprotease, peroxidase and lysozyme activities. Moreover, the feeding of MOL revealed an upregulation of the intestinal mucosal immunity genes (lyso and c3), tight junction proteins (occludin and zo-1) and anti-inflammatory cytokines (tgf-β) with a downregulation of pro-inflammatory cytokine (tnf-α). Therefore, it is recommended to incorporate MOL in S. aurata diets at a level of 5% for the best immune status or 10% for the high growth performance and acceptable immune surveillance.
An outdoor pot experiment was conducted in 2014/2015 growing season at Giza Agricultural Research Station to evaluate powdery mildew (PM) severity on 18 flax lines. The tested lines were divided into two distinct groups. The first group included 12 highly resistant lines (HRLs). Disease severity on these lines ranged from 1 to 10%. The second group included 6 highly susceptible lines (HSLs) where disease severity ranged from 90–100%. Levels and activities of phenols, alkaloids, proteins, proline, polyphenol oxidase and peroxidase significantly increased in the infected leaves of the HRLs, compared with the HSLs. Of these components, phenols and peroxidase showed the highest increases in the HRLs (102.34 and 199.33%, respectively). These results indicate that the tested biochemical components have roles to play in flax defense against PM through a variety of mechanisms. The results also suggest that phenols or peroxidase in infected leaves could be used in breeding programs to select resistant lines at early stage of PM development. 相似文献
Feed has been reported as a vehicle for transmission of Salmonella enterica in cattle and several lines of evidence suggest that feed can be a vehicle for transmitting Escherichia coli O157:H7 as well. To show whether microbial contamination of feeds could contribute to the populations of S. enterica and E. coli O157:H7 on a farm, we compared isolates from feed samples to bovine fecal isolates from the same farm using pulsed-field gel electrophoresis (PFGE). Four of 2365 component feed samples (0.2%) and 1 of 226 feed mill samples (0.4%) were positive for E. coli O157:H7. Twenty of 2405 (0.8%) component feed samples and none of 226 feed mill samples were positive for Salmonella. PFGE profiles from E. coli O157:H7 isolated from a component feed sample closely resembled that from a fecal isolate collected later from the same farm, and a similar observation was made of a Salmonella Tyhpimurium isolate from component feed on another farm. There were indistinguishable PFGE profiles from component feed Salmonella Tyhpimurium DT104 isolates and fecal isolates from the same farm. These results provide evidence for a role of cattle feed in transmission of E. coli O157:H7; S. enterica; cattle-bacteria. 相似文献
ABSTRACT Resistance of mature berries of grapevine cultivars and selections to postharvest infection by Botrytis cinerea was assessed. Little or no resistance existed in most popular table grape Vitis vinifera cultivars, except in moderately resistant 'Emperor' and 'Autumn Black'. Highly resistant grapes were V. rotundifolia, V. labrusca, or other complex hybrids. Morphological, anatomical, and chemical characteristics of 42 genetically diverse cultivars and selections with various levels of resistance to B. cinerea were examined to determine which features were associated with resistance. We quantified the (i) density of berries within a cluster; (ii) number of pores and lenticels on the berry surface; (iii) thickness and number of cell layers in the epidermis and external hypodermis; (iv) amount of cuticle and wax; (v) berry skin protein content; (vi) total phenolic content of the skin before and after B. cinerea inoculation; and (vii) catechin and trans- and cis-resveratrol contents of the skin before and after inoculation. The number of pores was negatively correlated with resistance. Highly resistant cultivars had few or no pores in the berry surface. The number and thickness of epidermal and hypodermal cell layers and cuticle and wax contents were positively correlated with resistance. Other characteristics evaluated were not associated with resistance. trans-Resveratrol and cis-resveratrol were induced by B. cinerea inoculation only in sensitive and moderately resistant cultivars and selections. 相似文献
Photolysis of isoxaben [N-[3-(1-ethyl-1-methylpropyl)isoxazol-5-yl]-2,6-dimethoxybenzamide] in dilute aqueous solutions, adsorbed on silica gel plates, has been investigated under natural and simulated solar light conditions. Eight photoproducts were isolated and identified by spectroscopic methods. Photo-decomposition with sunlight led to the formation of three isomers, dimethoxy-benzonitrile and dimethoxybenzamide as major photoproducts. The rearrangement has been shown to proceed in two photochemical steps by way of an azirine and a non-identified photoproduct as stable intermediates. The azirine rearranges almost quantitatively to an oxazole and rearranges back to the starting isoxaben. 相似文献