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  • 1
    Electronic Resource
    Electronic Resource
    Relationships between morphological and chemical characteristics of perennial ryegrass varieties and intake by sheep under continuous stocking management (2004)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 59 (2004), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Plots of five intermediate-heading varieties of perennial ryegrass (Lolium perenne L.) [AberDove, Belramo and Glen (diploid); Twins (tetraploid); and AberExcel (tetraploid hybrid)] were continuously stocked with sheep to maintain a target sward surface height of 40–50 mm. Daily dry matter (DM) intake was significantly different (F-value = 0·032) between the varieties, with the tetraploid hybrid AberExcel having the highest values for daily DM intake and intake rate during eating. Amongst the diploid varieties, intake rate tended to be higher for sheep grazing Glen. The varieties comprised a wide range in potential growth habit, from the relatively prostrate, highly tillered Glen to the more-erect AberExcel and there were differences between them in the vertical distribution of leaves within the sward canopy. The leaves of AberExcel weighed 3·6 mg DM cm−2 leaf area in contrast to the other varieties (4·3–5·3 mg DM cm−2 leaf area) resulting in a high leaf area index (LAI) in relation to the green leaf mass. Intake rate was not significantly correlated with extended tiller and sheath tube lengths, partition of herbage mass, number of tillers per square metre or LAI. However, canonical variates analysis showed that there were significant differences between the varieties for the morphological and chemical factors examined. Other factors also need to be explored to explain these differences in ingestive behaviour in order to identify plant traits that are correlated with herbage intake rate. These are needed for varieties destined for grazing use, both during the breeding programme and their subsequent evaluation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2004.00440.x
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  • 2
    Electronic Resource
    Electronic Resource
    Intake characteristics of perennial ryegrass varieties when grazed by yearling beef cattle under rotational grazing management (2005)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 60 (2005), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Four intermediate-heading perennial ryegrass (Lolium perenne L.) varieties, which in previous studies had been associated with high- or low-intake characteristics when swards containing them had been continuously stocked with sheep, were sown as monocultures. They were rotationally grazed, using 1-d paddocks, with core groups of four yearling Simmental × Holstein beef heifers in 2002 and 2003 and ingestive and ruminative behaviour, and sward factors, were measured. There were two diploid (Belramo and Glen) and one tetraploid (Rosalin) perennial ryegrass varieties and one tetraploid hybrid (Lolium × boucheanum Kunth) (AberExcel) variety. Intake rate (IR) was significantly higher in August 2003 for heifers grazing Glen than those grazing Belramo [27·5 vs. 20·6 g dry matter (DM) min−1; P = 0·019], but there were no significant differences between varieties in two other measurement periods. This is in contrast to previous results with sheep when IR were significantly higher for Glen than Belramo and for AberExcel than Rosalin. Total jaw movement rates during grazing were significantly higher for heifers on the tetraploid swards than those on the diploid swards (87·7 vs. 83·6 jaw movements min−1; P = 0·023) in September 2002. Ruminating time was significantly lower for heifers on the tetraploid swards than those on the diploid swards (453 vs. 519 min 24 h−1; P = 0·012) in July 2002. Digestibility of grass snips was significantly higher on the tetraploid than the diploid swards [697 vs. 680 g digestible organic matter (DOM) kg−1 DM; P = 0·042] in September 2003 and, within diploids, was significantly higher for Glen than Belramo (696 vs. 663 g DOM kg−1 DM; P = 0·014). There were significant differences in sheath tube and leaf lengths and in the population density of tillers between and within ploidies, which might have been expected to have influenced intake characteristics, but this was not generally found under rotational grazing with cattle. In order to separate the effects of defoliation interval from those of grazing style of the different ruminant species, it is suggested that grass variety evaluations using continuously stocked cattle swards are required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2005.00463.x
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymes as silage additives 2. The effect of grass dry matter content on silage quality and performance in sheep (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 46 (1991), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Eight grass silages were made from two contrasting varieties of perennial ryegrass, four silages each from a late-cut early-maturing (high dry matter, HDM) variety and from an early-cut, late-maturing (low dry matter, LDM) variety. The grass was ensiled without additive (untreated), or with formic acid, or with one of two enzyme mixtures of hemicellulases and cellulases (enzyme 1 and enzyme 2) for a period of 130 d.Formic acid-treated silage had lower levels of lactic acid at both levels of dry matter than the other silages. Enzyme treatment of grass prior to ensilage resulted in reduced levels of cellulose, acid-detergent fibre and neutral-detergent fibre in LDM silages and lower acid-detergent fibre and neutral-detergent fibre in the HDM silages compared with the corresponding untreated and formic acid-treated silages. Voluntary intakes (g DM d−1) of untreated and enzyme-treated silages were significantly (P〈0·01) lower at both digestibilities compared with formic acid-treated silages (LDM: untreated, 982; formic, 1069; enzyme 1, 868; enzyme 2, 937; HDM: untreated, 931; formic, 1027; enzyme 1, 943; enzyme 2, 914). The organic matter, carbohydrate and nitrogen digestibility coefficients of LDM silages were significantly (P〈0·001) higher than those of HDM silages. There were no significant differences in any component digestibility related to silage additive.Comparison of digestibility coefficients for constituents of the LDM silages fed to sheep or steers showed no differences between species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1991.tb02222.x
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  • 4
    Electronic Resource
    Electronic Resource
    The intake and feeding value for young beef cattle of two cultivars of tetraploid Italian ryegrass when grazed or conserved by artificial dehydration or ensilage (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 37 (1982), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Two experiments were carried out to determine whether the differences in intake and feeding value previously shown between two grass cultivars when offered to ruminants as chopped artificially dehydrated (dried) material could also be demonstrated when the grasses were offered in other forms. Two cultivars of tetraploid Italian ryegrass (Lolium multiflorum), Sabalan and Tetila, were established in the same field in 1975. In 1976 they were grazed and conserved (two cuts of primary growth) as dried material or as silage.The composition of the herbage selected at pasture and conserved showed higher concentrations of normal detergent fibre and acid detergent fibre in the dry matter for Tetila than for Sabalan, but differences between cultivars in digestibility were small. In both grazing and winter feeding trials differences in voluntary intake between the two cultivars were not significant, but at pasture young beef cattle spent less time grazing and tended to spend more time ruminating on Tetila than Sabalan. There was no measure of animal performance at pasture but liveweight gain was 15% higher for Sabalan than Tetila when both were offered to young beef cattle as the sole feed of dried grass or of silage. The voluntary intakes of the three forms of feed were very similar, which in part reflected a similarity in digestibility. However, gains were lower for calves given silage than those given dried grass. This may have been due to a lower efficiency in the utilization of the nitrogeneous components of silage for tissue growth than those of dried grass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1982.tb01573.x
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  • 5
    Electronic Resource
    Electronic Resource
    Neuronal and glial cell types revealed by NADPH-diaphorase histochemistry in the retina of a teleost fish, the grass goby (Zosterisessor ophiocephalus, Perciformes, Gobiidae) (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 487-494 
    Details
    ISSN: 1432-0568
    Keywords: Key words Nitric oxide synthase ; Müller cell ; Horizontal cell ; Retinal ganglion cell ; Mosaic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The grass goby is a mud-burrowing fish with a rich retinal vasculature appropriate to its hypoxic habitat. NADPH-diaphorase histochemistry was performed on retinal sections and wholemounts to reveal cells that contain nitric oxide synthase and so may be presumed to synthesise nitric oxide, a gaseous intercellular messenger with many roles including vasodilation. Structures that were consistently stained by this method included cone ellipsoids, horizontal cells, Müller cells and their processes, large displaced ganglion cells in the inner nuclear layer (identified by their axons), large interstitial ganglion cells in the inner plexiform layer, and capillary endothelial cells. In wholemounts, horizontal cells were seen to form a regular pattern, contacting each other at their dendritic terminals. Some cells in the ganglion cell layer were weakly stained, but stained bipolar and amacrine cells were not seen. The diaphorase-positive large ganglion cells all formed large, sparsely branched dendritic trees, arborizing near the scleral border of the inner plexiform layer. The displaced and interstitial cells seemed to belong to distinct morphological types, the interstitial cells having smaller somata and trees. Analysis of their spatial distributions in one representative retina confirmed this: the displaced cells formed a highly regular mosaic with a mean spacing (nearest-neighbour distance) of 303 µm, whereas the interstitial cells formed a separate mosaic, almost as regular but with a smaller mean spacing of 193 µm, rising to 217 µm in a sample that excluded the area retinae temporalis. Spatial correlogram analysis showed that these two mosaics were spatially independent. Nitric oxide probably has many roles in the retina. The presence of its synthetic enzyme in Müller cells, which communicate with retinal blood vessels, is consistent with a role in the control of retinal blood flow. Its function in large, mosaic-forming retinal ganglion cells is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050297
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  • 6
    Electronic Resource
    Electronic Resource
    A pattern of optic axons in the normal goldfish tectum consistent with the caudal migration of optic terminals during development (1983)
    Springer
    Experimental brain research 52 (1983), S. 147-151 
    Details
    ISSN: 1432-1106
    Keywords: Optic axons ; Normal development ; Synaptic plasticity ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Optic axons were cut in the goldfish optic nerve or tectum, filled with horseradish peroxidase and traced in tectal wholemounts. Many of them ran in conspicuous fascicles which curved across the tectum. Axons from central nasal retina, which ran in the most rostral fascicles, turned abruptly as they left these fascicles; ran caudally in a diffuse, parallel array for up to half the tectal length; and passed beneath more caudal fascicles to innervate the caudal half-tectum. Axons from peripheral nasal retina ran in the most caudal fascicles and terminated near their turning-points. Axons from temporal retina entered the tectum at its rostral margin and ran caudally from their points of entry to innervate the rostral halftectum. The resultant pattern was entirely consistent with the proposal that a slow caudal migration of optic terminals compensates during normal development for disparate modes of retinal and tectal growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237159
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  • 7
    Electronic Resource
    Electronic Resource
    A sharp retinal image increases the topographic precision of the goldfish retinotectal projection during optic nerve regeneration in stroboscopic light (1987)
    Springer
    Experimental brain research 68 (1987), S. 319-328 
    Details
    ISSN: 1432-1106
    Keywords: Retinotectal projection ; Topography ; Correlated activity ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Locally-correlated neural activity appears to play a key role in refining topographically mapped projections. The retinotectal projection of the goldfish normally regains a high degree of spatial precision after regeneration of a cut optic nerve, but it fails to do so if retinal ganglion cell activity is blocked by tetrodotoxin, or if local correlations in activity are masked by the synchronizing effect of stroboscopic light. A sharp retinal image is not normally needed for a sharp map because local correlation occurs even in darkness or diffuse light, but the possibility that a sharp image might restore local correlation and sharpen the map in stroboscopic light, though taken into account in earlier experiments, has not previously been tested. The precision of the retinotectal map was therefore studied, by retrograde transport of WGA-HRP from a standard tectal injection site and quantitative analysis of the labelled ganglion cell distribution, after regeneration of a cut optic nerve for 83–84 days in either continuous stroboscopic light or normal diurnal light. The lens of the eye was either ablated to blur the retinal image or sham-operated. Two different strobe flash patterns used in previous experiments were also compared. With the lens ablated, stroboscopic light impaired map refinement significantly, confirming previous results. A rapid, irregular flash pattern averaging about 5 Hz was rather more effective than a regular 1 Hz pattern. With the lens intact, however, neither pattern had any detectable effect. The significant gain in precision resulting from a sharp retinal image in these circumstances suggests that common mechanisms could underlie both the internal refinement of the retinotectal map and such directly experience-sensitive processes as the experimental realignment of binocular maps in the frog Xenopus, and of auditory and visual maps in the barn owl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248798
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  • 8
    Electronic Resource
    Electronic Resource
    Tectal paths of regenerated optic axons in the goldfish: Evidence from retrograde labelling with horseradish peroxidase (1983)
    Springer
    Experimental brain research 51 (1983), S. 433-442 
    Details
    ISSN: 1432-1106
    Keywords: Optic axons ; Regeneration ; Optictectum ; Retrograde tracing ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To compare the distributions of normal and regenerated optic axons in the goldfish tectum, small groups of axons crossing the rostromedial tectum were cut and filled with horseradish peroxidase which subsequently revealed the retinal locations of their somata. In normal fish, the peroxidase-filled ganglion cells were virtually confined to a narrow arc spanning the ventronasal quadrant of the retina. In fish with regenerated visual projections (50–736 days after optic nerve transection, optic nerve crush or deflection of optic axons to the ipsilateral tectum) the filled cells were distributed across the full extent of the retina from centre to periphery and were less rigidly confined within appropriate quadrants. The absence of any detectable arc of filled cells in the ventronasal quadrant after regeneration showed that few, if any, of the regenerated axons followed their original paths across the tectum. Quantitative analysis of local cell distributions indicated that axons were re-routed independently rather than in groups. Nevertheless, axons consistently displayed a crude bias towards appropriate tectal regions, even in ipsilateral tecta where the relative positions of these regions are inverted. These results imply that regenerating optic axons are widely scattered by the effects of surgery. They may subsequently show preferences for appropriate central paths but with a resolution too low to define much more than the orientation of the retino-tectal map. Since there is both anatomical and electrophysiological evidence that regenerated optic terminal arborizations eventually adopt a precise retinotopic arrangement, this arrangement must chiefly reflect ordering mechanisms which act in the final stages of axon growth or synapsis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237880
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  • 9
    Electronic Resource
    Electronic Resource
    Topographic refinement of the regenerating retinotectal projection of the goldfish in standard laboratory conditions: a quantitative WGA-HRP study (1986)
    Springer
    Experimental brain research 63 (1986), S. 409-420 
    Details
    ISSN: 1432-1106
    Keywords: Retinotectal projection ; Regeneration ; Topography ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The topographic precision of the regenerating retinotectal projection of the goldfish was studied between 18 and 524 days (at 20° C) after optic nerve cut, using retrograde transport of wheatgerm agglutinin conjugated to horseradish peroxidase (WGA-HRP) from one of two standardized tectal injection sites. All labelled ganglion cells in each flat-mounted retina were plotted individually, and their degree of dispersion was assessed by a statistical method based on distance to nearest neighbour. Labelled cells in normal fish were clustered tightly, covering on average only 1.3% of the retina. Early in regeneration (18–28 days) they were widely dispersed, covering up to 75.2%, and they did not begin to form recognizable clusters at appropriate sites until about 35 days after nerve cut. Between 18 and 70 days, the proportion of retina covered by labelled cells fell dramatically, halving about every 14 days. Between 70 and 524 days, no further reduction could be demonstrated: overall, clusters remained significantly larger than normal, though a few individual retinae were virtually normal. Several others, labelled from similar single injections between 56 and 524 days after nerve cut, showed pairs of cell clusters; a sign that persistent errors in topography are common. The very wide initial scatter of labelled cells reflects a striking lack of ‘goal-directedness’ in regenerative axon growth. Extensive branching in the optic nerve, tract and tectum, for which there is already evidence, must contribute to this. Though uptake of some WGA-HRP by non-synaptic growth cones cannot be ruled out, other evidence for mislocated functional synapses at early stages encourages us to favour ‘trial and error’ synapse formation as the likely basis of map refinement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236860
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  • 10
    Electronic Resource
    Electronic Resource
    Impaired refinement of the regenerated retinotectal projection of the goldfish in stroboscopic light: a quantitative WGA-HRP study (1986)
    Springer
    Experimental brain research 63 (1986), S. 421-430 
    Details
    ISSN: 1432-1106
    Keywords: Retinotectal projection ; Topography ; Correlated activity ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The retinotectal projection of the goldfish was studied after regeneration of a cut optic nerve in stroboscopic light, constant light or diurnal light, with the lens removed to blur the retinal image. Retrograde transport of wheatgerm agglutinin, conjugated to horseradish peroxidase, from a standard tectal injection site was used to measure the topographic precision of the projection. The dispersion of labelled retinal ganglion cells, which reflects this precision, was assessed by a method based on distance to nearest neighbour. In normal fish treated similarly, these cells are known to be clustered into about 1% of the retinal area. Early in regeneration, however, they are widely dispersed. The projection map then re-acquires its precision over two or three months. In diurnal light, lens ablation had no effect on refinement of the regenerated map. Constant light increased the number of labelled cells but also had no significant effect on the map. But in stroboscopic light with a continuous pseudorandom pattern of flash intervals (average rate 4.8 Hz), much less refinement was seen. Even after 70–98 days of regeneration, labelled cells remained scattered, on average, over 20% of the retinal area. These retinae were indistinguishable by several criteria from those obtained in diurnal light after only 32–39 days. Mislocated axon terminals, which are largely eliminated during the second and third months of regeneration in diurnal light, evidently persist much longer in stroboscopic light that synchronizes ganglion cell activity across the retina. These results, like previous ones obtained by blocking the transmission of activity to the tectum, support a model of map refinement based on correlation in the firing of neighbouring neurons, which may have wide application within the nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236861
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