The aim of the present study was to determine the optimum dietary levels of krill phospholipids (KPL) for sea bream (Sparus aurata) larvae, and its influence on larval development and digestive enzymes activity. Larvae were fed five formulated microdiets with five different levels of KPL. Complete replacement of live preys with the experimental microdiets for seabream larvae produced high survival and growth rates, particularly in fish fed the highest levels of KPL. In the present study, increase in dietary KPL up to 120 g kg?1 (100 g kg?1 total PL) significantly improved larval survival and growth, whereas further increase did not improve those parameters. An increase in alkaline phosphatase, trypsin and lipase activity with the elevation of KPL up to 120 g kg?1 was also found denoting a better functioning of digestive system. Besides, there was a linear substrate stimulatory effect of dietary KPL on phospholipase A2 activity. Finally, increasing dietary KPL lead to better assimilation of n‐3 HUFA especially eicosapentaenoic acid, reflected in the higher content of these fatty acids in both neutral and polar lipids of the larvae. In summary, KPL were found to be an excellent source of lipids for seabream larvae. Optimum inclusion levels of this ingredient in microdiets to completely substitute live preys at this larval age were found to be 120 g kg?1 KPL. 相似文献
In previous studies, we observed dystrophic alterations in muscle of 48‐day‐old sea bass fed imbalanced docosahexaenoic acid (DHA) and vitamin E diets. To understand the whole pathological process associated with oxidative stress, a histological study was performed by feeding 14‐day‐old sea bass larvae with microdiets containing different ratios of DHA/vitamin E (1/150, 5/150 and 5/300) for a period of 21 days. Larvae fed diet 1/150 showed no lesions in contrast to larvae fed diets 5/150 and 5/300 where the highest incidence of muscle lesions and thiobarbituric acid reactive substances (TBARS) content was observed. Semithin sections revealed focal lesions consisting of degenerated fibres with hypercontracted myofilaments and extensive sarcoplasm vacuolization affecting both red and white muscle. Ultrathin sections of degenerating muscle fibres showed diffuse dilatation of sarcoplasmic reticulum, disorganized myofilaments and autophagic vacuoles containing myelin figures and dense bodies. Additionally, some macrophages were observed among injured fibres as numerous satellite cells. Results from the study agree with those obtained from previous work, proving the pathological potential of free radicals in sea bass larvae musculature. Moreover, high vitamin E inclusion could not completely protect cell membranes from free radicals action. 相似文献
There is a need for management strategies to control dominant perennial weeds and restore seminatural communities. We compared the effects of five weed control treatments on dense Pteridium aquilinum relative to an untreated experimental control over an 8‐year period with the aim of restoring acid grassland. The weed control treatments tested were as follows: cutting and bruising, both twice and thrice annually, and herbicide treatment (asulam in year 1 followed by annual spot retreatment of all emergent fronds). Pteridium aquilinum performance and plant species composition were monitored. Data were analysed using Bayesian mixed‐effect models and multivariate techniques. Cutting twice and thrice yearly and the asulam treatment all reduced frond density to zero; both bruising treatments were ineffective. The plant communities in the cut and asulam‐treated plots showed differences from the untreated and bruised plots; the asulam‐treated plots contained more ruderal species and the cut plots were more typical of acid grassland. Acid grassland recovery was fastest in the asulam‐treated plots, but the cut plots caught up after approximately 5 years. There were two important conclusions. First, an intractable weed like P. aquilinum can be eradicated and a vegetation more suited for grazing can be achieved by the continuous application of some treatments over many years. Here, success was achieved by cutting twice/thrice annually, or by a single asulam application followed by annual spot spraying of all emergent fronds for 8 years. Second, bruising, a treatment favoured by some conservation organisations, did not work and cannot be recommended. The use of long‐term, continuously applied treatments might be considered for all perennial weeds with large underground root/rhizome systems. 相似文献
The dry matter yield (DMY), in vitro organic matter digestibility (IVOMD) and crude protein (CP) content of eleven grasses were studied during the years 1992 to 1994 under mob grazing conditions. Offered and consumed dry forage do not differ significantly (P<0.05) among the highest yielding accessions Cynodon nlenfuensis PRPI 2341, Cynodon plectostachium PRPI 11487, and Cynodon dactylon cv. Tifton 85. However, the commercial Cynodon nlenfuensis PRPI 2341 was consistently the highest yielding accession both years. Among the other grasses, Digitaria eriantha showed the lowest levels of refused dry forage, thus presenting the best forage acceptability by grazing animals. Digitaria eriantha also showed the highest levels of IVOMD in both the short and the long day seasons. It is concluded that none of the evaluated Cynodon dactylon accessions from southern United Sates, nor the digitaria and brachiaria species adapted better than the commercial accession Cynodon nlenfuensis PRPI 2341. Warm‐season perennial grasses are grown extensively in the southeastern United States. Among the grasses, one of the most widely grown is from the species Cynodon dactylon, commonly named bermudagrass (Eichhorn, 1984). The choice of a bermudagrass cultivar for establishment of pastures is an important decision for cattlemen seeking high weight gains of stocker steers throughout the warm grazing season of the southern United States (Greene et al., 1989). Selection of improved bermudagrass hybrids has dramatically increased forage yield over that of common bermudagrass. Improved forage quality has also resulted in improved performance of grazing animals fed harvested hybrid bermudagrass forage (Gates et al., 1989). Reports on average daily weight gains (ADG) of yearling steers grazing different bermudagrass hybrids varied between 0.68 to 0.79 kg animal‐1 day‐1 during the summer season of southern Louisiana (Faw et al., 1986). Hill et al. (1993) in Tifton, GA, found yearling ADG of 0.67 and 0.65 kg animal‐1 day‐1 for the recent bermudagrass releases Tifton 85 and Tifton 78, respectively. Forage quality dry matter yield and grazing performance support the hypothesis that Tifton 85 will likely become an important hay and grazing forage for the southern United States. In Puerto Rico, Cynodon nlenfuensis PRPI 2341 (stargrass) is at present the grass cultivar most frequently grown on dairy farms (Ramos‐Santana and Randel, 1996). Yearly ADG of 0.59 kg animal‐1 day‐1 has been reported for young steers grazing stargrass in the humid tropical zone of Puerto Rico (Vicente‐Chandler et al., 1983). At Ona, FL, lower ADG of 0.54 kg has also been obtained with stargrass (Mislevy, 1989). The objective of this paper is to compare the agronomic performance (dry matter yield and quality) of six of the most outstanding bermudagrass hybrids from the southern United States, with five tropical grasses from the cynodon, brachiaria, and digitaria genera under the tropical conditions of central Puerto Rico. 相似文献
Aims: To assess the inter-observer agreement for detecting bovine digital dermatitis (BDD) lesions in digital colour photographs of the hind feet of cows, which had been taken while the animals were standing to be milked, between two trained observers.
Methods: Thirty-six photographs were selected from a total of 184 photographs held by the first author (R1), who had classified them as negative (n=11) or positive (n=25) for BDD. They were delivered to a technician (R2) who had previously visually inspected cattle for BDD lesions, and who then recorded the photographs as being either BDD-positive or BDD-negative. The percentage agreement between R1 and R2, and two other inter-observer agreement statistics, Cohen’s κ and Gwet’s first-order chance correction agreement coefficient (AC1), were calculated. The cumulative membership probabilities of Cohen’s κ and Gwet’s AC1 were then calculated for different benchmark ranges of κ.
Results: The percentage agreement between R1 and R2 was 33/36 (92%), Cohen’s κ was 0.80 (95% CI=0.57–1.0) and Gwet’s AC1 was 0.86 (95% CI=0.69–1.0). Based on the cumulative membership probabilities for Gwet’s AC1, there was 75% probability that the two observers had almost perfect agreement (κ≥0.81). For both Cohen’s κ and Gwet’s AC1, there was >95% probability that the two observers had at least substantial agreement (κ≥0.61).
Conclusions: The two trained observers had at least substantial agreement in identifying from a digital photograph as to whether BDD lesions were present or absent. Therefore results from the two could be used interchangeably.
Clinical Relevance: Visual assessment for BDD lesions in the milking parlour can be subjective. However a high agreement between these two trained BDD inspectors means BDD prevalence reported from different regions in New Zealand by these two can be directly compared. 相似文献
BACKGROUND: Cerebrospinal fluid (CSF) is produced in the cerebral ventricles through ultrafiltration of plasma and active transport mechanisms. Evaluation of proteins in CSF may provide important information about the production of immunoglobulins within the central nervous system as well as possible disturbances in the blood-brain barrier. OBJECTIVE: The objective of this study was to measure the concentration and fractions of protein in CSF samples using a membrane microconcentrator technique followed by electrophoresis, and to compare the protein fractions obtained with those in serum. METHODS: CSF samples from 3 healthy dogs and 3 dogs with canine distemper virus infection were concentrated using a membrane microconcentrator having a 0.5 to 30,000 d nominal molecular weight limit (Ultrafree, Millipore, Billerica, MA, USA). Protein concentration was determined before and after concentration. Agarose gel electrophoresis was done on concentrated CSF samples, serum, and serial dilutions of one of the CSF samples. RESULTS: Electrophoretic bands were clearly identified in densitometer tracings in CSF samples with protein concentrations as low as 1.3 g/dL. The higher CSF protein concentration in dogs with distemper was mainly the result of increased albumin concentration. CONCLUSION: The microconcentrating method used in this study enables characterization of the main protein fractions in CSF by routine electrophoresis and may be useful for interpreting the underlying cause of changes in CSF protein concentrations. 相似文献