A Procedure for Measuring the Digestibility of Pasture Forage under Grazing Conditions

Reid, J. T.; Woolfolk, P. G.; Hardison, W.A.; Martin, Christian; Brundage, Adrienne; Kaufmann, R.W.

doi:10.1093/jn/46.2.255

Cited by 78 publications

(25 citation statements)

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“…Apart from their use as a measure of feeding value, digestibility data are becoming of particular use in determining forage intake in pasture studies. The feed/faeces ratio technique [Garrigus (11)], [Woodman (39)], the lignin ratio technique [Eorbes (8)] and the chromogen and methoxyl ratio techniques [Reid (26)] have been developed from data on the digestibility of forages. As more precise techniques are required, more accurate data on forage digestibility will be necessary.…”

Section: Discussionmentioning

confidence: 99%

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Studies on the Digestibility of Herbage

Raymond¹,

Harris²,

Harker³

1953

Grass and Forage Science

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Section: Discussionmentioning

confidence: 99%

“…(e) Chromogen. The method described by Reid et al (26) is followed, except that, to increase the accuracy of sampling of the fresh faeces, macerated faeces are used. Fifteen grm.…”

Section: Chemical Analysesmentioning

confidence: 99%

Studies on the Digestibility of Herbage

Raymond¹,

Harris²,

Harker³

1953

Grass and Forage Science

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“…They are expressed even in a stable nutritional environment (Kay 1979; Adam et al 1986 to maintain body energy throughout the year (Blaxter 1989 (Moen 1973(Moen , 1985 (Jiang 1993 Lignin content was determined using 72% stlfuric acid according to Goering and van Soest (1970). Chromogen determination followed the method of Reid et al (1953).…”

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confidence: 99%

Seasonal energy requirements of wapiti (Cervus elaphus) for maintenance and growth

Jiang¹,

Hudson²

1994

Can. J. Anim. Sci.

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“…This will introduce errors into the technique by an incorrect estimate of the concentration of tracer in the 'herbage grazed', and these may be most serious under range conditions, where stock may graze a number of different ecological units during the day, REID et al (27) have suggested that the need for pasture sampling for chromogen content may be obviated by calculating the chromogen content of 'herbage grazed' from the measured chromogen content in faeces collected, using the relationship:…”

Section: Discussionmentioning

confidence: 99%

“…A further requirement of 'indigestible plant tracer' techniques is the sampling of the sward by the experimenter to obtain a sample of herbage representative of that grazed by stock, SALTONSTALL (30), comparing the composition of a 'plucked' herbage sample with that of 'grazed' herbage (collected through a rumen fistula) has emphasized the difficulty of obtaining a truly representative sample, even under restricted pasture conditions. This will introduce errors into the technique by an incorrect estimate of the concentration of tracer in the 'herbage grazed', and these may be most serious under range conditions, where stock may graze a number of different ecological units during the day, REID et al (27) have suggested that the need for pasture sampling for chromogen content may be obviated by calculating the chromogen content of 'herbage grazed' from the measured chromogen content in faeces collected, using the relationship: However the precision of this estimate is probably less than appears from equation [3], because the values for 'chromogen in forage consumed' used in calculating the equation were calculated from the corresponding faecal chromogen values, assuming 100 per cent indigestibility of the chromogen, and were not obtained by actual measurement.…”

Section: Discussionmentioning

confidence: 99%

Studies in the Digestibility of Herbage

Raymond¹

1954

Grass and Forage Science

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The measurement of pasture output raises many problems, because harvesting is carried out by grazing stock, and yields cannot be measured directly, as with grains, roots, hay and silage. Pasture output is also a function of management, and seasonal yield is frequently of more importance than total annual yield.Methods used in pasture studies have been reviewed and recommendations made by a Committee on pasture research (17). These include the use of 'unit grazing days' [VINALL (35) ], total digestible nutrient output [KNOTT et al. (22)] and mowing techniques, as well as some of the techniques described below. While mowing methods frequently give good agreement with output measured as T.D.N.'s or Starch Equivalent, this is usually only found over prolonged grazing trials, when cumulative output figures are used. Thus LINEHAN et a/. (24) have shown that over a period of three years a clipping method has given an output 101 per cent of that obtained from animal data. During individual grazing periods, however, output from clippings varied from 66 to 252 per cent of animal output. This illustrates the difficulty of evaluation of output over short periods. Some of the reasons for this have been discussed by GREEN (13). who indicated the large numbers of herbage samples that are required to obtain an accurate measure of consumption, and stressed the importance of sampling herbage at a level lower than that to which stock will graze. However, under certain conditions and with the taking of large numbers of samples, useful output data can be obtained: thus WAITE et al.(36) have measured the output of'strip' grazing, under which the errors introduced by differential growth, discussed by LINEHAN (24) are largely eliminated. SEARS (31) has described a method in which herbage in 'protected' areas is plucked until it is similar in appearance to grazed areas, but here allowance for herbage growth during the grazing period is difficult, and the method is basically subjective. The use of a 'browse unit' method has been suggested for range conditions by COOK et al. (3).The use of animal output as a measure of pasture production requires considerable numbers of animals because of individual variations in maintenance and production requirements. Moreover it is uncertain how far standards for maintenance and production, obtained in indoor experiments, are strictly valid in the field. Its application to short grazing periods is doubtful: thus TAYLER (34) has indicated the difficulty in measurement of liveweight increase due to variations in 'fiir. Little is known also about the energy expenditure in grazing.In general, the precision of measurement of pasture output by mowing techniques or animal output data is inadequate and interest is now largely concerned with alternative methods of evaluation. Of these, methods involving collection and chemical analysis of faeces show promise, and are being widely studied. There appear to be two quite distinct approaches in use, namely the use of indigestible tracer substances in the feed and t...

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A Procedure for Measuring the Digestibility of Pasture Forage under Grazing Conditions

Cited by 78 publications

References 1 publication

Studies on the Digestibility of Herbage

Studies on the Digestibility of Herbage

Seasonal energy requirements of wapiti (Cervus elaphus) for maintenance and growth

Studies in the Digestibility of Herbage

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