Energy sources for detritivorous fishes in the Amazon     

Araujo-Lima CA  Forsberg BR  Victoria R  Martinelli L 《Science (New York, N.Y.)》1986,234(4781):1256-1258

Detritivorous fishes form an important part of the ichthyomass in the Amazon basin. Most of these fishes are contained in the orders Characiformes and Siluriformes (catfishes). The Characiformes constitute more than 30% of the total fish yield in the Amazon basin, whereas the catfishes are of minor importance. Stable isotope data indicate that Characiformes species receive most of their carbon through food chains originating with phytoplankton, while the Siluriformes receive a significant part of their energy from other plant sources.  相似文献   

Influence of light environment and photoperiod on plasma melatonin and cortisol profiles in young domestic boars, comparing two commercial melatonin assays     

Andersson H  Lillpers K  Rydhmer L  Forsberg M 《Domestic animal endocrinology》2000,19(4):261-274

Eighteen crossbred boars, three siblings from each of six litters, were distributed randomly among three groups after weaning. The ‘Natural long-day’ group was housed in a standard room with windows, whereas the ‘Artificial long-day’ and ‘Artificial short-day’ groups were housed in light-sealed rooms and under an artificial light regimen (1400 lx). In spring (16–17 hr of light) plasma levels of melatonin and cortisol were measured in samples collected hourly for 24 hr. Two commercial melatonin radioimmunoassays with preassay diethyl ether extraction were compared. Only the assay from Bühlmann Laboratories AG showed low to undetectable melatonin levels during the light-phase and was used for further analysis. Dark-phase melatonin concentrations were higher than light-phase melatonin concentrations (P < 0.001). Dark-phase melatonin concentrations were higher in the ‘Natural long-day’ group than in the ‘Artificial long-day’ and the ‘Artificial short-day’ groups (P < 0.001). Sire had a significant effect on dark-phase melatonin concentrations (P < 0.01), but not on light-phase levels. Cortisol concentrations were higher during the light-phase than during the dark phase, and light-phase cortisol concentrations were higher in the ‘Natural long-day’ group than in the ‘Artificial long-day’ and the ‘Artificial short-day’ groups (P < 0.01). This study showed that peripubertal boars express a typical circadian melatonin rhythm under both artificial light regimens and in standard pig stable environment. Natural photoperiod and indoor lighting seem to interact in shaping the melatonin profile in standard stable environment. The great individual variation in the amplitude of the dark-phase melatonin levels could in this study be explained by the different sires.  相似文献   

Assessing Pearl Quality Using Reflectance UV-Vis Spectroscopy: Does the Same Donor Produce Consistent Pearl Quality?     

Mamangkey NG  Agatonovic S  Southgate PC 《Marine drugs》2010,8(9):2517-2525

Two groups of commercial quality ("acceptable") pearls produced using two donors, and a group of "acceptable" pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones) showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver) showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected with UV-Vis spectrophotometry. Nevertheless, this technique could have a role to play in developing less subjective methods of assessing pearl quality and in further studies of the relationships between pearl quality and that of the donor and recipient oysters.  相似文献   

Organic and inorganic selenium: I. Oral bioavailability in ewes     

Hall JA  Van Saun RJ  Bobe G  Stewart WC  Vorachek WR  Mosher WD  Nichols T  Forsberg NE  Pirelli GJ 《Journal of animal science》2012,90(2):568-576

Although the essentiality of dietary Se for sheep has been known for decades, the chemical source and Se dosage for optimal health remain unclear. In the United States, the Food and Drug Administration (FDA) regulates Se supplementation, regardless of the source of Se, at 0.3 mg of Se/kg of diet (as fed), which is equivalent to 0.7 mg of Se/d or 4.9 mg of Se/wk per sheep. The objectives of this study were to evaluate the effects of Se source (inorganic vs. organic) and supplementation rate (FDA vs. supranutritional rates of 14.7 and 24.5 mg of Se/wk) on whole-blood (WB) and serum-Se concentrations. Mature ewes (n = 240) were randomly assigned to 8 treatment groups (n = 30 each) based on Se supplementation rate (4.9, 14.7, and 24.5 mg of Se?wk(-1)?sheep(-1)) and source [Na-selenite, Na-selenate (4.9 mg/wk only), and organic Se-yeast] with a no-Se control group (0 mg of Se/wk). Treatment groups were balanced for healthy and footrot-affected ewes. For 1 yr, ewes were individually dosed once weekly with 0, 4.9, 14.7, or 24.5 mg of Se, quantities equivalent to their summed daily supplementation rates. Serum- and WB-Se concentrations were measured every 3 mo in all ewes; additionally, WB-Se concentrations were measured once monthly in one-half of the ewes receiving 0 or 4.9 mg of Se/wk. Ewes receiving no Se showed a 78.8 and 58.8% decrease (P < 0.001) in WB- (250 to 53 ng/mL) and serum- (97 to 40 ng/mL) Se concentrations, respectively, over the duration of the study. Whole-blood Se decreased primarily during pregnancy (-57%; 258 to 111 ng/mL) and again during peak lactation (-44%; 109 to 61 ng/mL; P < 0.001). At 4.9 mg of Se/wk, Se-yeast (364 ng/mL, final Se concentration) was more effective than Na-selenite (269 ng/mL) at increasing WB-Se concentrations (P < 0.001). Supranutritional Se-yeast dosages increased WB-Se concentrations in a dose-dependent manner (563 ng/mL, 14.7 mg of Se/wk; 748 ng/mL, 24.5 mg of Se/wk; P < 0.001), whereas WB-Se concentrations were not different for the Na-selenite groups (350 ng/mL, 14.7 mg of Se/wk; 363 ng/mL, 24.5 mg of Se/wk) or the 4.9 mg of Se/wk Se-yeast group (364 ng/mL). In summary, the dose range whereby Se supplementation increased blood Se concentrations was more limited for inorganic Na-selenite than for organic Se-yeast. The smallest rate (FDA-recommended quantity) of organic Se supplementation was equally effective as supranutritional rates of Na-selenite supplementation in increasing WB-Se concentrations, demonstrating the greater oral bioavailability of organic Se.  相似文献   

Internationalization of the animal science undergraduate curriculum: a survey of its current status,barriers to its implementation and its value     

Forsberg NE  Taur JS  Xiao Y  Chesbrough H 《Journal of animal science》2003,81(4):1088-1094

The goal of this project was to identify the current level at which internationalization has been adopted as a theme in the North American animal science curriculum and to identify its value and the barriers to its implementation. We surveyed animal, dairy, and poultry science departments across Canada and the United States. One hundred twenty-four surveys were mailed and 60% were returned. Associations between aspects of internationalization and student outcomes (admission to veterinary and graduate schools and starting salaries) were examined. Although administrators strongly believed internationalization had value, implementation was limited. The most common practices included international content in core animal science classes, advising, international internships, and participation of faculty in international scholarly activities. Few departments have incorporated internationalization into their mission statements or developed a specific international-themed class, scholarships devoted to international activities, or roles for international students. Few departments reported participation of students in international programs. Barriers included finances and limited commitment from higher administration. Student outcomes were positively associated with faculty size, percentage of international faculty, the ratio of international students to the total student population, international content in core animal science classes, a specific international-themed class, availability of international internships, and exchange of class material internationally via the Internet. Departments that did not offer international opportunities had a negative association (r = -0.79) with starting salary, but these relationships may not be causal. Alternatively, progressive departments may attract and retain exceptional students. The analysis indicated an awareness of the value of international programs, positive impacts in student outcomes, and financial barriers to implementation.  相似文献   

The acute phase protein serum amyloid A (SAA) as an inflammatory marker in equine influenza virus infection   总被引：1，自引：0，他引：1  

Hultén C  Sandgren B  Skiöldebrand E  Klingeborn B  Marhaug G  Forsberg M 《Acta veterinaria Scandinavica》1999,40(4):323-333

The acute phase protein serum amyloid A (SAA) has proven potentially useful as an inflammatory marker in the horse, but the knowledge of SAA responses in viral diseases is limited. The aim of this study was to evaluate SAA as a marker for acute equine influenza A2 (H3N8) virus infection. This is a highly contagious, serious condition that inflicts suffering on affected horses and predisposes them to secondary bacterial infections and impaired performance. Seventy horses, suffering from equine influenza, as verified by clinical signs and seroconversion, were sampled in the acute (the first 48 h) and convalescent (days 11-22) stages of the disease, and SAA concentrations were determined. Clinical signs and rectal temperature were recorded. Secondary infections, that could have influenced SAA concentrations, were clinically suspected in 4 horses. SAA concentrations were higher in the acute stage than in the convalescent stage, and there was a statistically positive relationship between acute stage SAA concentrations and clinical signs and between acute stage SAA concentrations and maximal rectal temperature. Horses sampled early in the acute stage had lower SAA concentrations than those sampled later, indicating increasing concentrations during the first 48 h. There was a statistically positive relationship between convalescent SAA concentrations and degree of clinical signs during the disease process. The results of this investigation indicate that equine SAA responds to equine influenza infection by increasing in concentration during the first 48 h of clinical signs and returning to baseline within 11-22 days in uncomplicated cases.  相似文献   

Control of Ovarian Activity in Llamas (Lama glama) with Medroxyprogesterone Acetate   总被引：1，自引：0，他引：1  

M.A. Aba    M.A. Quiroga  N. Auza  M. Forsberg  H. Kindahl 《Reproduction in domestic animals》1999,34(6):471-476

Contents Progesterone and progestogens have proved to be effective in controlling follicle development and synchronization of ovarian activity in different species. In this study, vaginal sponges containing 120 mg medroxyprogesterone acetate were used to synchronize ovarian activity in llamas and to predict the time when a mature follicle will be present. Plasma concentrations of oestradiol-17β and progesterone were measured to determine follicle and corpus luteum development. The sponges were kept in the vagina for 9 days. Six days after sponge withdrawal, ovulation was induced by either GnRH injection (n = 4), mating with a vasectomized male (n = 8) or mating with an intact male (n = 10). Plasma progesterone concentrations varied between animals until day 6 after insertion of the sponges. Thereafter, progesterone levels remained close to the detection limit of the assay until ovulation was induced. The mean oestradiol-17β plasma concentration reached its lowest value 3–4 days after insertion of the sponges. Thereafter, concentrations increased and reached peak levels at day 6 after withdrawal of the sponges. All animals ovulated and developed a corpus luteum with a normal life span after the ovulatory stimulus. Blood samples were collected frequently after mating to evaluate the endocrine response to copulation. Plasma concentrations of PGF_2α metabolite and cortisol increased in parallel after copulation. The metabolite concentrations returned to basal levels 3–4 h after mating whereas the cortisol concentrations remained elevated for about 12 h after copulation The luteinizing hormone secretory pattern resembled that reported when llamas with a mature ovulatory follicle were mated. In conclusion, the protocol evaluated in this study was shown to be useful for the synchronization of ovarian activity and for predicting the time when an ovulatory follicle will be present in llamas.  相似文献   

Carbon sources of Amazonian fisheries   总被引：1，自引：0，他引：1  

E. Benedito-Cecilio  C. A. R. M Araujo-lima  B.R. Forsberg  & M.M. Bittencourt  L. C. Martinelli 《Fisheries Management and Ecology》2000,7(4):305-315

Variation in the seasonal and spatial isotopic composition of plant C₄ (aquatic macrophytes) and C₃ (forest, C₃ aquatic macrophytes and algae), and that of fish [ Prochilodus nigricans Agassiz, Mylossoma duriventre (Cuvier), Colossoma macropomum (Cuvier), Semaprochilodus insignis (Schomburgk) and S. taeniurus Steindachner in the Amazon floodplain were analysed to test whether the fisheries deliver plant carbon to the population of Manaus in the same proportion as it is available in the floodplain. The contribution of C₄ plants was significantly lower in ¹³C during the season of high water levels and increased toward the west of the basin. Mylossoma duriventre and C. macropomum changed δ¹³C levels, while the δ¹³C of P. nigricans and C. macropomum shifted spatially. The contribution of C₄ to the fisheries yield was small. C³ plants (excluding phytoplankton) also contributed less than expected. This was explained by the importance of detritivores to the yield of the fisheries and the dependence of these species on algal carbon.  相似文献   

Ammonia excretion rates from post-smolt Atlantic salmon, Salmo salar L., in land-based farms     

O I Forsberg 《Aquaculture Research》1996,27(12):937-944

Empirical data on ammonia excretion rates were compiled from several published and unpublished growth studies on post-smolt Atlantic salmon, Salmo salar L. Fish in all studies were fed to satiation with commercially produced high-energy diets (ME = 18–19 MJ kg^-1) with a protein content of 40–45%. About 35 ± 3% (mean SE) of the nitrogen supplied to fish was excreted as total ammonia (TAN = NH₃-N + NH₄⁺-N). The results of a linear regression analysis of N intake to N excretion demonstrated, however, that TAN excretion rates could be divided into two components: TAN_excretion [g N kg fish^-1 day^-1] = 0.036 + 0.26 N_intake [g N kg fish^-1 day^-1]. The intercept of the regression equation indicates that the endogenous TAN excretion rates in post-smolts could be estimated as 36 mg TAN kg fish^-1 day^-1, and about 26% of the nitrogen supplied to the fish was excreted postprandially. This postprandial TAN excretion was lower than that from other salmonid species fed low-energy diets. The daily maximum TAN excretion rate was about 43% higher than daily mean values, which agree with several studies. The ammonia quotient (A.Q.) measured was independent of the nitrogen supplied, and was calculated as 0.112. The outputs from the present model were compared to those from other ammonia excretion models.  相似文献   

The risks and benefits of re-consent     

Forsberg JS  Hansson MG  Eriksson S 《Science (New York, N.Y.)》2011,332(6027):306; author reply 306

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