The Use of Fecal Nitrogen as a Measure of Dry Matter Intake and of Digestibility of Organic Matter in Forage

Homb, T.; Breirem, K.

doi:10.2527/jas1952.113496x

Cited by 14 publications

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“…1 shows equations [2] and [10], and Fig. 2 equations [4] and [15]. It is seen that neither LANCASTER'S nor RI-ID'S equations coincide with those obtained in this study.…”

Section: Numbers Of Animalssupporting

confidence: 60%

“…of a predicted value is emphasized. 4. The use of the in digestibility coefficient to calculate herbage intake from faecal production in the field leads to errors higher than those apparent in the original estimate of digestibility.…”

Section: Numbers Of Animalsmentioning

confidence: 97%

“…The relevant comparisons are, for nitrogen, equations [2] and [10], and for chromogen [4] and [15] These equations are not ofthe same form, and are best compared graphically. Fig.…”

Section: Numbers Of Animalsmentioning

confidence: 99%

“…HOMB and BRIEREM (4), commenting on this technique, have implied that LANCASTER assumes nitrogen excretion per 100 grm. dry matter intake to be constant, whereas these authors show this to be positively correlated with per cent crude protein in the forage, the correlation depending on the type of forage.…”

Section: Introductionmentioning

confidence: 95%

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Studies in the Digestibility of Herbage

Raymond

Kemp

et al. 1954

Grass and Forage Science

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INTRODUCTIONIn the previous paper (Part III) the use of techniques which assume certain constituents in forage to be indigestible was discussed. These, together with the feed : faecal ratio techniques suffer from the main disadvantage that they require the sampling of a sward for 'herbage as grazed', which is a subjective operation. They also assume 100 per cent recovery in the faeces of herbage constituents such as lignin or ehromogen, while particular care must be taken in obtaining representative samples of faeces in the field.However the main error in these techniques lies in herbage sampling, and alternative methods which do not require this sampling are being investigated.Using data from indoor digestion experiments, RAYMOND (12) suggested that the composition of faeces produced by grazing stock might be used as an indirect measure of the composition of the herbage grazed. This showed a relationship between the nitrogen contents of herbage and the resulting faeces, % N in ash-free herbage = 0-28 i 0-85 x % N in ash-free faeces [1] and suggested that information on the nutritive value of herbage might be obtained from such relationships. Using similar data, LANCASTER (8, 9) proposed a general relationship between the digestibility of the organic matter in herbage and the nitrogen content of faeces produced:% digestibility of organic matter in herbage = 100(1 \ [2] \ % N in ash-free faeces/ Based on all the data, C ^ 0-76, but more precise estimates were obtained by using C ^ 0-67 for herbage feeds below 15 per cent crude protein and C = 0-80 for feeds above 15 per cent crude protein. HOMB and BRIEREM (4), commenting on this technique, have implied that LANCASTER assumes nitrogen excretion per 100 grm. dry matter intake to be constant, whereas these authors show this to be positively correlated with per cent crude protein in the forage, the correlation depending on the type of forage. However, as noted above, LANCASTER (8) made some allowance for the nitrogen content of the forage. FORBES (2) has proposed an equation taking full account of forage composition: ", , , , ,. , "" /% protein in herbagex % herbage dry matter digested =100 -I \ x \% protein in faeces/ (^100 -42-64 X (% protein in herbage -5%) \ [3] In this however the main advantage of the faecal index method has been lost, in that an estimate of the composition of 'herbage grazed' is required.In connection with their study ofthe use of chromogen as an 'indigestible tracer', REID et al. (16) have noted that an estimate of herbage digestibility can be made without measuring, directly 69 or indirectly, the chromogeti contetit of 'herbage grazed'. They proposed a relationship between herbage digestibility and the chromogen content ofthe resulting faeces: % digestibility of herbage D.M. = O'O168 X + 8-47 log X + 32-74 [4] where X = units chromogen/grm, dry faeces. (Standard error of estimate of digestibility = 0-44%).In a discussion ofthe use of faecal chemical analysis, RAYMOND (13) suggested a study ofthe correlation between herbage digestibility...

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“…1 shows equations [2] and [10], and Fig. 2 equations [4] and [15]. It is seen that neither LANCASTER'S nor RI-ID'S equations coincide with those obtained in this study.…”

Section: Numbers Of Animalssupporting

confidence: 60%

Section: Numbers Of Animalsmentioning

confidence: 97%

“…The relevant comparisons are, for nitrogen, equations [2] and [10], and for chromogen [4] and [15] These equations are not ofthe same form, and are best compared graphically. Fig.…”

Section: Numbers Of Animalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

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Studies in the Digestibility of Herbage

Raymond

Kemp

et al. 1954

Grass and Forage Science

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“…He suggested that the relationship might be used to estimate the intake of pasture. Although it was later shown that the value of y was not constant (Forbes, 1949;Woolfolk et al 1950;Homb & Brierem, 1952;Leroy, 1952;and Hutchinson & Porter, 1958), a number of workers have found that for particular pastures I is related in a highly significant manner to FN (Milford, 1957;Hutchinson, 1958;Osman, 1958;Fels, Moir & Rossiter, 1959;and Scaut, 1959).…”

Section: Basis Of Faecal Nitrogen-^intake Relationshipsmentioning

confidence: 94%

The use of faecal nitrogen as an index for estimating the consumption of herbage by grazing animals

Arnold

Dudziński

1963

J. Agric. Sci.

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Data from thirty-five digestibility trials with sheep in metabolism cages were used to investigate statistically the relationships between organic matter intake (I), faecal organic matter output (F), and the nitrogen concentration in faecal organic matter (N).The data fell easily into groups due to botanical or seasonal differences in the feed. These groups of data were homogeneous and provided highly significant linear equations of the forms I = bF + cFN and I = a + cFN. When compared these groups of data sometimes showed differences in slope, position or both. A quadratic expressionI = bF + cFN + dFN2was found to accommodate a majority of the data but to be less precise than I = a + cFN.A further expression incorporating N as an independent variable was also examined,I = a + cFN2 + eN.This expression, although far from being universally adequate, proved to be generally better than existing formulae. When applied to the data of Greenhalgh et. al. (1960), it substantially reduced heterogeneity between data for spring and data for summer pastures.Causes of variation in the relationship between organic-matter intake and nitrogen in faeces, and some of the hazards of extrapolation from empirical regression relations, are discussed.

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The estimation of the intake of grazing sheep I. Establishment of faecal nitrogen regressions

1962

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1. Regression equations for the ratio of organic matter (O.M.) feed intake to O.M. faecal output on faecal N%, and the N% in the O.M. intake on faecal N% were established over a 52-week period by feeding caged Corriedale wethers on pasture cut from a Wimmera rye-grass (Lolium rigidum Gaud.), subterranean clover (Trifolium subterraneum) sward in a Mediterranean-type environment.2. The regression equations and their application to grazing sheep together with the relation between O.M. intake and faecal N, are discussed.

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The Use of Fecal Nitrogen as a Measure of Dry Matter Intake and of Digestibility of Organic Matter in Forage

Cited by 14 publications

References 0 publications

Studies in the Digestibility of Herbage

Studies in the Digestibility of Herbage

The use of faecal nitrogen as an index for estimating the consumption of herbage by grazing animals

The estimation of the intake of grazing sheep I. Establishment of faecal nitrogen regressions

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