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  • 1
    Electronic Resource
    Electronic Resource
    The diet ingested by sheep grazing swards differing in white clover and perennial ryegrass content (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: A series of twenty-four swards containing different proportions of white clover (0·20-0·25) and perennial ryegrass were created by using different seed mixtures, herbicide applications and previous cutting Frequencies. These swards were used to study the diet of oesophageally-fistulated wether sheep which grazed the various swards for a 30-min period after 1, 2 and 3 weeks of regrowth.The proportion of white clover in the diet was generally greater than that in the sward. Fifty-seven percent of the variation in the proportion of white clover in the diet could be attributed to the proportion of white clover in the sward. White clover and perennial ryegrass leaf and stem were grazed to the same height and the proportion of white clover in the grazed horizon of the sward explained 83% of the variation in the proportion of white clover in the diet. The proportion of white clover in the diet was greater than the proportion in the grazed horizon of the sward in week 3 of regrowth, but not in weeks 1 and 2, and greater when the proportion of white clover in the grazed horizon was lower than 0·20. Both these observations were interpreted as indicating selection for white clover by the sheep within the grazed horizon.There was a positive and linear relationship between the depth of the grazed horizon and sward height which, together with the relationship between the proportion of white clover in the grazed horizon and in the diet, would allow the prediction of the proportion of white clover of the diet from the height and the white clover content of the grazed horizon of the sward.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1982.tb01598.x
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  • 2
    Electronic Resource
    Electronic Resource
    Variations in the surface characteristics of the sward and the short-term rate of herbage intake by calves and lambs (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 36 (1981), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The results are reported of an examination of detailed measurements on the ingestive behaviour of calves and lambs in response to variations in the surface characteristics of swards under strip-grazing and continuous stocking managements. It is shown that intake per bite and the short-term rate of herbage intake were both sensitive to the height of the surface horizon above ground level but, at least under strip-grazing management, not to variations in herbage density in the grazed horizon. The rate of biting was less sensitive to variations in sward conditions, particularly under strip-grazing.Both intake per bite and rate of intake were more sensitive to variations in grazing height under strip-grazing, where sward changes were rapid, than under continuous stocking, where they were slow. Under continuous stocking, ingestive behaviour was more sensitive to changes in sward conditions in lambs than in calves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1981.tb01538.x
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of haymaking strategies for cow-calf systems in the Salado Region of Argentina using a simulation model. 3. Exploratory risk assessment (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: Risk and cost estimates, calculated using a weather-driven farm simulation model, were used to evaluate the impact of different haymaking strategies in dryland cow-calf systems such as those in the Salado region of Argentina. Based on a 100-ha farm, each strategy was simulated using twenty sequences of 50 years of random weather. A risk-efficiency methodology was used, using calf live weight sold and considering the economic value of the live weight produced per year minus the cost of haymaking, as a simple measure of profit. The analysis highlighted both production and risk advantages in using hay, especially when a flexible hay management approach was implemented, although some haymaking strategies performed worse than not using hay. When calf live weight sold was considered alone, the risk-efficient set included strategies with large proportions of the areas being harvested (0.42–1.05; paddocks could be cut more that once a year in some of the strategies) and high proportions of hay not being used. The amount of hay for maximizing risk efficiency for profit was notably lower than that for maximizing cattle production. When haymaking costs were included, the proportion of area harvested for risk-efficient profit ranged from 0.28 to 0.52, depending on the target stocking rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2005.00494.x
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of haymaking strategies for cow-calf systems in the Salado Region of Argentina using a simulation model. 2. Incorporation of flexibility into the decision rules (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: In pastoral farming systems, pasture production normally exceeds demand in the spring–summer period. Consequently, conserving forage at this time for use during the following winter is a widespread practice. The objective of this study was to assess the possible advantages of incorporating flexibility into a calendar-based haymaking policy. A range of flexible haymaking strategies were simulated and compared against a calendar-based strategy by using a simulation model to estimate long-term performance of cow-calf farm systems under each strategy. The results suggest that controlling haymaking in a flexible fashion, basing the decisions of closing, releasing and cutting paddocks on a simple pasture budget, could give the system productive advantages over using a calendar-based approach. In terms of liveweight production per hectare, compared at the same area harvested, the flexible approach had higher average annual calf liveweight production (an increase of up to 0.15) and lower system variability [a reduction of 0.10 in the coefficient of variation (CV)] depending on the stocking rate. The results indicated that allocating more than 0.50–0.60 of the farm area to conservation would only be advantageous at very high stocking rates. In contrast to the calendar-based strategy, making more hay than required for the immediate next winter, where possible, can reduce system variability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2005.00493.x
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in plant population density, composition and sward structure of a hill pasture during a pastoral fallow (1997)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 52 (1997), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Appropriate pre-sowing methods for the introduction of improved forage legume and grass germplasm are an important issue for hill pasture improvement in New Zealand. A pastoral fallow, which involves not defoliating pasture for a period generally from late spring/early summer to autumn, could create a potentially favourable environment for introducing improved germplasm. A field study was conducted on two aspects (shady and sunny) of moist, low-fertility hill country with or without added fertilizer (phosphorus and sulphur) in the southern North Island of New Zealand, to investigate the changes in plant population density and sward structure during a full or partial pastoral fallow, compared with a rotationally grazed pasture. A 7-month (October to May) pastoral fallow dramatically decreased the densities of grass tillers by 72% (P 〈 0·01), white clover (Trifolium repens L.) growing points by 87% (P 〈 0·01) and other species by 87% (P 〈 0·05). The decline in tiller density by pastoral fallow was enhanced on the shady aspect. Fertilizer application increased white clover growing-point density on the shady aspect (P 〈 0·05) and grass tiller density on the sunny aspect (P 〈 0·05). Decreased plant density during pastoral fallowing was attributed to aboveground biomass accumulation, which altered sward structure, leading to interplant competition and mortality by self-thinning and completion of the life cycle of some matured plants. The plant size-density relationship during pastoral fallowing in this mixed-species sward followed the serf-thinning rule, particularly when the calculation was based on all plant species rather than grass alone. There was no significant (P 〉 0·05) difference in final plant population density between the 7-month pastoral fallow and a shorter term (October to December) pastoral fallow. It is concluded that pastoral fallowing effectively reduced the plant population density and altered sward structure of a hill pasture. Such changes create a more favourable environment for the introduction of improved forage species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1997.tb02349.x
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  • 6
    Electronic Resource
    Electronic Resource
    The effects of change in herbage mass on rates of herbage growth and senescence in mixed swards (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 39 (1984), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A study was conducted to determine the influence of a change in herbage mass on rates of herbage growth (G), senescence (S) and net production of green herbage (NP) in swards of Lolium perenne L., Poa annua L. and Trifolium repens L. under continuous stocking with sheep. Swards were maintained at either high (1700–1900 kg OM ha−1; H) or low (700–900 kg OM ha−1; L) herbage mass from April to 20 August. From 20 August to 13 September half of the L sward was permitted to grow until a herbage mass similar to that of the H sward was achieved (LH), and at the same time half of the H sward was grazed down until a herbage mass similar to that of the L sward was achieved (HL). The other half of each sward was held at constant mass (LL and HH). Estimates of G, S and NP were obtained for each plant species over a 2-week period from 17 September to 1 October and estimates of species population densities were also made.The combined species rates of G and S per unit area were highest in treatment LH and lowest in treatment HL, whilst the rates for the LL and HH swards were intermediate. The rate of NP was similar in the LL, HH and LH treatments (34.5, 29.3, 33.6 ± 6.2 kg DM ha−1d−1) but was lower in the HL sward (100 ± 6.2). The effects of alteration of herbage mass on individual tiller or stolon G and S rates were rapid but population density changes were slower.Within the limited conditions of this trial it was not possible to increase NP by manipulation of herbage mass under continuous stocking management but the results indicate that NP can be reduced in the short term if a sward of high herbage mass and low population density is grazed hard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1984.tb01672.x
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  • 7
    Electronic Resource
    Electronic Resource
    The development and use of equipment for the automatic recording of ingestive behaviour in sheep and cattle (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 36 (1981), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A description is given of equipment designed to be fitted to either sheep or cattle, and to record automatically information on the jaw movements associated with both grazing and ruminating, movements of the head in plucking mouthfuls of herbage, and the time spent in grazing. The equipment has been successfully tested against alternative visual and mechanical methods of measuring grazing behaviour.The use of modified equipment in detailed studies has shown (a) that the maximum acceleration of the head in a longitudinal plane when plucking mouthfuls of herbage was twice as great in sheep as in cattle and in the sheep, but not in the cow, increased as sward height decreased; and (b) that the ratio of jaw movements to head movements was always greater than unity in both sheep and cattle, and was greater on tall than on short swards in two out of three comparisons. The rate of biting was significantly lower on tall than on short swards.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1981.tb01545.x
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  • 8
    Electronic Resource
    Electronic Resource
    Variations in herbage mass and digestibility, and the grazing behaviour and herbage intake of adult cattle and weaned calves (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 36 (1981), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Two experiments are described in which groups of lactating cows, non-lactating cattle and weaned calves grazed a sequence of swards varying in maturity and herbage mass under strip grazing management at a daily herbage allowance of 60 g dry matter per kg live weight. Lactating cows ate 43% and 76% more herbage than non-lactating cattle of similar weight in the two experiments but herbage OM intakes per unit live weight by the calves and lactating cows were similar.Variations in diet digestibility and herbage intake in the lactating and non-lactating cattle with changes in sward conditions were similar. In the first experiment the calves were experienced grazers; the variation in the digestibility of the herbage selected was less in the calves than the adult cattle, but the variation in herbage intake was greater. The calves in the second experiment were younger, and they were inexperienced grazers; their ability to increase herbage intake in response to changing sward conditions was poorer than that of adult cattle, though variations in diet digestibility were similar in all classes.The practical implications of these results are discussed briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1981.tb01537.x
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  • 9
    Electronic Resource
    Electronic Resource
    Comparison of haymaking strategies for cow-calf systems in the Salado Region of Argentina using a simulation model. 1. Effect of herbage mass at cutting and cow stocking rate under a rigid system of 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: A simulation model was used to compare the long-term performance of cow-calf farm systems under different haymaking strategies on a 100-ha farm. In the simulation, farm management was based on that which had been developed on Reserva 6, an experimental cow-calf farm established in 1966 at Instituto Nacional de Tecnología Agropecuaria-Balcarce Experimental Station, Argentina, where different technologies, including haymaking, have been adapted and applied in order to increase productivity of cow-calf systems in the Salado Region of Argentina. The management of the system is based on a restricted mating season (2 months), early weaning (5–7 months of age) and forage conservation. The simulations showed that the effect of using hay with respect to the strategy without hay, in terms of calf liveweight (LW) production per hectare, was greatest at the cow numbers that maximized production (290–320 cows) with a proportionate increase of 0.25. On the other hand, the advantage of using hay was smallest when the herbage mass at cutting for hay was 6 t dry matter (DM) ha−1, particularly when more than 0.50 of the farm area was allocated to haymaking. The differences among the haymaking policies increased with cow numbers, especially at high herbage masses at cutting for hay. The analysis also suggested that the LW production per hectare of cow-calf farms would be maximized by harvesting 0.40–0.50 of the total farm area and aiming to cut hay at a herbage mass of 4 t DM ha−1 and with medium quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.2005.00492.x
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  • 10
    Electronic Resource
    Electronic Resource
    Regrowth, morphology and persistence of Grasslands Puna chicory (Cichorium intybus L.) in response to grazing frequency and intensity (1997)
    Oxford, UK : Blackwell Science Ltd
    Grass and forage science 52 (1997), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Effects of different grazing frequencies and intensities on herbage production (on both a unit pasture and individual plant basis) and on persistence of chicory (Cichorium intybus L. cv. Grasslands Puna) were studied at Palmerston North, New Zealand (latitude 40°23′S) from November 1994 to November 1995. Three experiments were conducted on the same chicory stand, sown on 12 May 1994. The main grazing experiment had two grazing intensities, hard-lax grazing (50- to 100-mm stem stubble to mid-January, and thereafter 100- to 150-mm stem stubble) and lax grazing (100- to 150-mm stem stubble), and three grazing frequencies (1-, 2- or 4-week intervals). A subsidiary plant survival experiment compared the survival of 120 marked plants in ungrazed and grazed treatments. A late autumn grazing experiment examined the effects on plant persistence in the following spring. The greatest herbage mass (leaf + stem) resulted from the 4-week grazing frequency [9640 ± 874 kg dry matter (DM) ha−1], in which stem mass was reasonably low (1270 ± 410 kg DM ha−1), but was significantly higher in the 4-week grazing frequency than 1- and 2-week grazing frequencies (P 〈 0·01). Grazing intensity had no significant effect except on the average stem mass of individual plants when the hard-lax intensity gave a lower stem mass (P 〈 0·01). There were no interactions between grazing frequency and intensity in herbage mass. Plant density declined by 35% over the growing season with the decline unaffected by grazing intensity or frequency during the season. Grazing in late autumn resulted in approximately 27% less plants the following spring. It was concluded that grazing management through the growing season cannot be used to improve persistence without compromising leaf growth rate, but that avoidance of grazing late autumn will improve the persistence of chicory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2494.1997.00051.x
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