The ability of the n-alkane technique to estimate intake and diet choice of sheep

Rm, Lewis; Am, Magadlela; Ns, Jessop; Gc, Emmans

doi:10.1017/s1357729800059051

Cited by 20 publications

(10 citation statements)

References 17 publications

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“…Unfortunately, faecal recovery of short even-chain alkanes is incomplete, increasing as the carbon chain length becomes longer. 5,8,9 In the present study, average faecal recoveries were 77% (SEM 1.7), 81% (SEM 4.6), 101% (SEM 2.6), 92% (SEM 2.8) and 95% (SEM 2.1) for C 24 , C 26 , C 28 , C 30 and C 32 alkanes respectively. Except for C 28 , whose faecal recovery was unexpectedly high, the recovery rates of dosed alkanes in the present study were in agreement with those reported by other authors.…”

Section: Discussionsupporting

confidence: 51%

Effects of carrier matrix and dosing frequency on digestive kinetics of even‐chain alkanes and implications on herbage intake and rate of passage studies

Giráldez¹,

Lamb²,

López

et al. 2004

J Sci Food Agric

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An experiment was carried out to investigate the digestive kinetics of various even-chain alkanes adsorbed into different carrier matrices and to assess their potential use to estimate faecal output, herbage intake and rate of passage in goats. The carrier matrices (alkanes) tested were cellulose powder (C 24 and C 28 alkanes), paper bungs (C 26 alkanes), Gilson paper filters (C 30 alkanes) and shredded paper (C 32 alkanes). Effects of carrier matrix and dosing frequency (once or twice daily) on diurnal fluctuations of faecal marker concentrations were simulated by modelling the faecal excretion curves of each marker. C 32 alkanes adsorbed into shredded paper showed the longest transit time (TT ) and the slowest fractional outflow rate from a fast compartment (k 2 ) and consequently a greater total mean retention time (TMRT ) than the other markers. In contrast, both C 24 and C 28 alkanes absorbed into cellulose powder showed the fastest k 2 and the shortest TT and TMRT. Our results suggest that relative differences in rate of passage associated with different nutritional treatments can be investigated using even-chain alkanes as rate of passage markers for comparative studies. Faecal outputs measured or estimated using C 28 , C 30 or C 32 alkanes as external markers were not significantly (P > 0.05) different, but the accuracy of estimation was higher with C 28 and C 32 alkanes (r = 0.81 and 0.83 respectively). On average, faecal output was significantly (P < 0.05) overestimated by 31% (SEM 9.4) and 35% (SEM 11.2) with C 24 and C 26 alkanes respectively. There were no significant (P > 0.05) differences between observed and estimated herbage intakes when pairs C 31 /C 30 and C 33 /C 32 were used, this latter pair of alkanes giving the best prediction. With the other alkane pairs (C 25 /C 24 , C 27 /C 26 and C 29 /C 28 ), estimates were biased, although actual and predicted values were significantly (P < 0.05) correlated. The simulation study revealed that, when markers were dosed twice a day, there were no significant (P > 0.05) differences between even-chain alkanes in the amplitude of the diurnal fluctuation of their faecal concentrations. However, when the marker administration was as a single dose per day, C 32 alkane absorbed into shredded paper resulted in the narrowest range of variation, with no significant differences among the other carrier matrices.

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Section: Discussionsupporting

confidence: 51%

Effects of carrier matrix and dosing frequency on digestive kinetics of even‐chain alkanes and implications on herbage intake and rate of passage studies

Giráldez¹,

Lamb²,

López

et al. 2004

J Sci Food Agric

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“…These "fingerprints" have already been explored with success to estimate the proportions of different plant species and/or plant parts in mixtures of ten herbage species (Hoebee et al, 1998) and from faeces of different animal species fed up to five dietary components in sheep (Lewis et al, 2003, Valiente et al, 2003, Ferreira et al, 2006, goats (Brosh et al, 2003, Ferreira et al, 2005, cattle (Brosh et al, 2003;Ferreira et al, in press) and equines (Ferreira et al, in press) in indoor controlled studies.…”

Section: Introductionmentioning

confidence: 99%

The use of n-alkanes to estimate diet composition of ruminants grazing on species diverse plant communities — Effect of feeding selectivity on diet composition estimates

et al. 2007

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The present study aimed to evaluate the effect of feeding selectivity (FS) within a dietary group comprising plant species with similar alkane profile, on the estimates of diet composition of goats, sheep and cows grazing on vegetation composed of gorseheathland with areas of improved pastures. Plant species collected in the field study were grouped in four dietary groups according to cluster analysis: D1 (Lolium perenne, Pseudarrhenatherum longifolium and Agrostis capillaris), D2 (Calluna vulgaris, Erica cinerea, Erica umbellata, Erica australis), while Erica arborea (D3) and Ulex gallii (D4) remained as individual components due to their distinct n-alkane profiles. The application of different levels of feeding selectivity (0, 5, 15, 30, 60, 90 and 100%) to the graminaceous species included in D1 group affected significantly (P b 0.05) the diet composition estimates as a result of the modification of the alkane pattern of the dietary group used in the calculations. However, this effect was not so evident within all ranges of FS and when evaluated in the heather species of D2 group. When L. perenne and C. vulgaris were removed from D1 and D2 dietary groups and treated as individual components, there was a decrease in the FS effect on the diet composition estimates. The results obtained show that dietary groups formed by multivariate statistical analysis should be used carefully as they could be sensitive to feeding selectivity, with consequently large effects on the estimates of diet composition. This effect will depend on the similarity in the alkane profile of the plant species that composed the dietary group.

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“…Therefore, the accuracy of diet estimates may change according to the n ‐alkanes present in the feed components (as well as with their concentrations) that the animals are eating. The majority of the studies with alkanes have been conducted with sheep and with vegetation where herbaceous species were dominant 11–13. The objective of the present work was to investigate the accuracy of using n ‐alkanes to estimate diet composition of goats when varying the proportions of browse and herb feeds in order to apply this technique to goats grazing mosaics of heather–gorse communities interspersed by patches of grass and clover.…”

Section: Introductionmentioning

confidence: 99%

Validation of the alkane technique to estimate diet selection of goats grazing heather–gorse vegetation communities

et al. 2005

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The effect of n-alkane faecal recovery on the accuracy of diet composition estimates, when increasing the number of diet components, was studied. Seven dietary treatments, composed of different proportions of herbaceous (Lolium perenne and Trifolium repens) and woody species (Erica umbellata, Erica cinerea, Calluna vulgaris, Erica arborea and Ulex gallii) were offered to 28 goats housed in metabolism crates. Diet composition was estimated from alkane concentrations in diet and faeces, with and without correction for incomplete faecal recoveries, using least-squares procedures and was compared with the known diet proportions. There were no significant differences between measured proportions of dietary components and those estimated with alkanes when applying the faecal recovery corrections. In contrast, the proportions calculated without faecal recovery correction differed significantly (p < 0.05) from the actual proportions, overestimating feeds with higher content of long-chain n-alkanes. The diet composition affected significantly the faecal recovery of alkanes if there were significant differences on in vivo digestibility. The n-alkane faecal recoveries decreased as the diet digestibility increased. The results obtained show that the application of the alkane methodology for grazing animals should be preceded by calculation of the actual alkane faecal recoveries for each type of vegetation community and experimental conditions.

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The ability of the n-alkane technique to estimate intake and diet choice of sheep

Cited by 20 publications

References 17 publications

Effects of carrier matrix and dosing frequency on digestive kinetics of even‐chain alkanes and implications on herbage intake and rate of passage studies

Effects of carrier matrix and dosing frequency on digestive kinetics of even‐chain alkanes and implications on herbage intake and rate of passage studies

The use of n-alkanes to estimate diet composition of ruminants grazing on species diverse plant communities — Effect of feeding selectivity on diet composition estimates

Validation of the alkane technique to estimate diet selection of goats grazing heather–gorse vegetation communities

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