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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 39 (1984), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The performances of a rising-plate meter and a single-probe electronic capacitance meter were compared for estimating the herbage mass of irrigated pastures both before and after grazing by dairy cows. Mean CV for the rising plate meter and the single-probe meter were 12.7% and 13.3% respectively when herbage mass was measured before grazing, and 21.8% and 15.4% respectively immediately after grazing. These coefficients of variation indicate that while the performance of the two meters was similar when herbage mass was measured before grazing, the single-probe meter was a more precise instrument for estimating herbage mass after grazing.Trampling of herbage prior to measurement had a major effect on the regressions of both meters; the regression intercept was increased by 2800 kg dry matter (DM) ha−1 for the rising-plate meter and by 2580 kg DM ha−1 for the single-probe meter. The slopes of the graphs, however, remained unchanged.It was concluded that while the single-probe meter performed better than the rising-plate meter for estimating the mass of post-grazing herbage when trampling was negligible, the large effect that trampling had on the post-grazing calibration regressions precluded both instruments from general use in dairy cattle research. This indicates that another technique is required in circumstances in which pastures are heavily trampled.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 38 (1983), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Information about the grazing behaviour and the return of dung to pasture by lactating dairy cows was collected from stocking rate experiments in northern Victoria. Grazing behaviour was observed for 24-h periods in mid-summer in two years. Grazing time increased as herbage allowance decreased to about 32 kg DM cow−1 d−1 but as herbage allowance decreased further grazing time also decreased. A herbage allowance of 32 kg DM cow−1 d−1 corresponded to a stocking rate of about 5.5 cows ha−1. This effect of herbage allowance on grazing time may have been confounded by herbage mass, however. Rumination time of the cows increased by 003 h for each kg increase in herbage allowance while resting time was not affected by treatment.The effects of stocking rate on some of the characteristics of faecal output were measured for a 3-d period in mid-summer. The number of pats deposited per cow daily declined by 0.66 for each unit increase in stocking rate. The fresh weight of dung also declined as stocking rate increased by 0.16 kg per unit of stocking rate. While the values for the amounts of dung deposited on the pasture by the cows at the lower stocking rates are similar to many of those reported in the literature, this study has quantified the way in which stocking rate may influence this in one instance. Furthermore, provided that some measure of herbage intake is made when measurements of dung excretion are performed, it is suggested that estimates of in vivo digestibility can be obtained.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 40 (1985), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Pasture variables measured in eight experiments at Kyabram, Victoria were used to quantify factors influencing the consumption of irrigated pastures grazed by dairy cows. In addition, whether intake prediction equations based on sward characteristics could be developed and applied in the field was also considered.Herbage intake (DMI) was positively related to herbage allowance (HA) in all cases; however, the increase in daily DMI achieved for every additional kg herbage offered to a cow ranged from 015 to 0·35 kg. Herbage intake was also consistently related to residual herbage (RH). For every additional tonne herbage dry matter (DM) ha−1 remaining after grazing, each cow consumed increased daily amounts of herbage ranging from 3·2 to 5·1 kg DM. However, of the other pasture variables, herbage mass (HM), pasture type (PT) and digestibility of the herbage DM on offer (DMD) influenced herbage intake less consistently.When the data from all experiments were included together, DMI was influenced by sward characteristics in the following manner: 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:01425242:GFS31:GFS_31_mu1"/〉 where LW = live weight of the cow (kg) and DE = duration of experiment (d).When RH was considered instead of HA, only 61% of the variability in intake was accounted for compared to 80% when HA was considered: 〈displayedItem type="mathematics" xml:id="mu2" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:01425242:GFS31:GFS_31_mu2"/〉 In both of these equations, two variables other than the sward characteristics were significant; these were LW and DE. The significance of these variables in these relationships are discussed together with the possibility of using them for predicting DMI in other environments. However, it is concluded that they do not have general applicability and it is suggested that they may be useful only in the environment in which they were generated.
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  • 4
    Publication Date: 1983-02-01
    Description: Herbage intake by grazing dairy cows can be estimated by measurements on the pasture ('t Mannetje, 1978) or by measurements on the animal (Raymond, 1969; Corbett, 1978). Of the sward sampling techniques, the difference method, based on pre- and post-grazing sampling, has the greatest potential for providing valid estimates of herbage intake, but only when grazing periods are short and stocking densities are relatively high (Pigden & Minson, 1969). Estimates of intake by measurements on the animal are made by the faecal output-indigestibility ratio technique (Raymond, 1969; Corbett, 1978). The most widely used marker for the determination of faecal output is chromic oxide (Cr2O3).
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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