Estimation of Digestibility of Grazed Pasture from Fæces Nitrogen

Lancaster, Robert

doi:10.1038/163330b0

Cited by 45 publications

(42 citation statements)

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“…During this study the relationships between herbage digestibility and both nitrogen and chromogen, as used by LANCASTER (8,9) and REID (16) respectively have been investigated, and it is possible to compare our regressions with theirs. 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.…”

Section: Numbers Of Animalsmentioning

confidence: 99%

“…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:…”

Section: Introductionmentioning

confidence: 97%

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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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Section: Numbers Of Animalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Studies in the Digestibility of Herbage

Raymond

Kemp

et al. 1954

Grass and Forage Science

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“…The chemical information contained in faeces is inherently representative of the consumed diet and is related to intake and digestibility. Using faecal indices to elucidate dietary attributes has long been practised (faecal N; Lancaster, 1949) and is still in use: in a recent study of sheep grazing a sward of Pennisetum americanum, David et al (2014) found that the faecal concentration of N and NDF explained 98% of the variation in organic matter (OM) intake.…”

Section: Introductionmentioning

confidence: 99%

Faecal near-IR spectroscopy to determine the nutritional value of diets consumed by beef cattle in east Mediterranean rangelands

Landau

Dvash

Roudman

et al. 2016

animal

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Rapid assessment of the nutritional quality of diets ingested by grazing animals is pivotal for successful cow-calf management in east Mediterranean rangelands, which receive unpredictable rainfall and are subject to hot-spells. Clipped vegetation samples are seldom representative of diets consumed, as cows locate and graze selectively. In contrast, faeces are easily sampled and their near-IR spectra contain information about nutrients and their utilization. However, a pre-requisite for successful faecal nearinfrared reflectance spectroscopy (FNIRS) is that the calibration database encompass the spectral variability of samples to be analyzed. Using confined beef cows in Northern and Southern Israel, we calibrated prediction equations based on individual pairs of known dietary attributes and the NIR spectra of associated faeces ( n = 125). Diets were composed of fresh-cut green fodder of monocots (wheat and barley), dicots (safflower and garden pea) and natural pasture collected at various phenological states over 2 consecutive years, and, optionally, supplements of barley grain and dried poultry litter. A total of 48 additional pairs of faeces and diets sourced from cows fed six complete mixed rations covering a wide range of energy and CP concentrations. Precision (linearity of calibration, R 2 cal, and of cross-validation, R 2 cv) and accuracy (standard error of cross-validation, SEcv) were criteria for calibration quality. The calibrations for dietary ash, CP, NDF and in vitro dry matter digestibility yielded R 2 cal values >0.87, R 2 cv of 0.81 to 0.89 and SEcv values of 16, 13, 39 and 31 g/kg dry matter, respectively. Equations for nutrient intake were of low quality, with the exception of CP. Evaluation of FNIRS predictions was carried out with grazing animals supplemented or not with poultry litter, and implementation of the method in one herd over 2 years is presented. The potential usefulness of equations was also established by calculating the Mahalanobis ( H) distance to the spectral centroid of a calibration population of 796 faecal samples collected throughout 2 years in four herds. Seasonal trends in pasture quality and responses to management practices were identified adequately and H < 3.0 for 98% of faecal samples collected. We conclude that the development of FNIRS equations with confined animals is not only unexpensive and ethically acceptable, but their predictions are also sufficiently accurate to monitor dietary composition (but not intake) of beef cattle in east Mediterranean rangelands.Keywords: nutrition, beef cattle, NIRS, monitoring, decision-making ImplicationsMarket globalization and climate changes threaten beef cattle grazing on east Mediterranean rangelands. Profitability requires adequate stocking rate and timely supplementation. Clipped samples of vegetation are seldom representative of the consumed diet. We present a methodology that obviates the need to obtain representative diet samples, based on the hypothesis that faeces contain ample information on diets consumed. We show ...

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“…Thus the equations proposed by Watson (35), Forbes (II, 12) and Lancaster (20) will have considerable validity, being based on data obtained by these workers. Errors are hkely, however, in the use of these equations by other workers, because the experimental techniques of the latter may vary from those of the original authors.…”

Section: (D) Age Of Animalsmentioning

confidence: 97%

“…The correlation of digestibility with crude fibre has been proposed by Axellson (3) and Hallsworth (15) and with lignin by Forbes (11,12). More general relations have been suggested by Mitchell (22) using protein and by Lancaster (20) using crude fibre, cellulose and lignin. Schneider (28) has shown that the use of such regressions can give a prediction error variance 25-40 per cent lower than when ' average ' digestion coefficients are used.…”

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confidence: 92%

The Problem of Measuring the Nutritive Value of Herbage

Raymond¹

1951

Grass and Forage Science

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As emphasis in modem grassland thought is placed increasingly on herbage quality (7), our inability to measure the feeding value of a sample of herbage, without recourse to a digestibility experiment, becomes more evident. This has been emphasized by Orampton (5); Mitchell (22) has suggested that the most promising approach to this problem is in the use of equations which relate the digestibility of a feed (in this case herbage) to its chemical composition.Watson (36) in 1936 suggested that for a limited range of swards the digestibility (from which they estimated the Starch Equivalent) of the herbage dry-matter could be estimated from its crude protein content. Similar regressions on crude protein have been suggested by Boyd (4) and Forbes (10). The correlation of digestibility with crude fibre has been proposed by Axellson (3) and Hallsworth (15) and with lignin by Forbes (11, 12). More general relations have been suggested by Mitchell (22) using protein and by Lancaster (20) using crude fibre, cellulose and lignin. Schneider (28) has shown that the use of such regressions can give a prediction error variance 25-40 per cent lower than when ' average ' digestion coefficients are used.The present paper considers the methods by which such relationships are established, and the likely limitations of the present approach to the problem, in view of the errors that are possible in these methods. In developing a suitable equation, the digestibilities and chemical compositions of a wide range of herbage samples must be measured. The validity of such an equation will depend on the reliability of these data, and we must thus consider how they are obtained, and how accurate they are likely to be.

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Estimation of Digestibility of Grazed Pasture from Fæces Nitrogen

Cited by 45 publications

References 4 publications

Studies in the Digestibility of Herbage

Studies in the Digestibility of Herbage

Faecal near-IR spectroscopy to determine the nutritional value of diets consumed by beef cattle in east Mediterranean rangelands

The Problem of Measuring the Nutritive Value of Herbage

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