Using plant wax markers to estimate diet composition and intakes of mixed forages in sheep by feeding a known amount of alkane-labelled supplement
E. Charmley A C and H. Dove BA Agriculture and Agri-Food Canada, Crops and Livestock Research Centre, Nappan, Nova Scotia B0L 1C0, Canada. Current address: CSIRO Livestock Industries, PO Box 5545, Rockhampton Mail Centre, Qld 4702, Australia.
B CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.
C Corresponding author. Email: ed.charmley@csiro.au
Australian Journal of Agricultural Research 58(12) 1215-1225 https://doi.org/10.1071/AR07187
Submitted: 15 May 2007 Accepted: 20 August 2007 Published: 17 December 2007
Abstract
The feeding of known amounts of supplements to grazing animals can be accomplished relatively easily. If the supplement and the other diet components have distinctive profiles of cuticular wax n-alkanes, then the supplement intake and the alkane profiles of the supplement, other dietary components and faeces can be used to estimate the proportions and hence intakes of several forages by the grazing animal. However, this method requires knowledge of recoveries of n-alkanes in faeces. Twenty four wethers were fed one of four diets comprising equal combinations of 1, 2, 3 or 4 forages. Forages used were subterranean clover, phalaris, annual ryegrass and wheat straw. Forages were chopped using a chaff cutter and fed with solvent-extracted cottonseed meal (CSM) labelled with beeswax and synthetic C28 alkane to provide a characteristic alkane profile. Faecal grab samples were taken from sheep from 14 to 23 days after administration of an intra-ruminal controlled-release device (CRD) containing 1 g of each of C32 and C36 alkane. Total faeces were collected from half the sheep on each treatment in order to measure alkane recoveries in individual sheep. Faecal concentrations of the n-alkanes C25 to C31 and C33 were corrected for recovery using the individual sheep value, the treatment mean or the grand mean for all four treatments. Dietary compositions were then estimated from corrected faecal concentrations of n-alkanes using a least-squares procedure and, together with the known supplement intakes, were used to estimate the intakes of all other diet components. Estimates from this ‘labelled supplement’ method were compared with the amounts fed or those estimated using the alkanes derived from the CRD. The labelled supplement method accurately and precisely estimated dietary component proportions and intake for all treatments when measured recoveries for individual sheep were used. Precision declined when recovery was based on estimated recoveries for treatment means or the grand mean. Estimates of intake based on dietary C33 and the measured release rates of C32 or C36 alkanes from the CRD did not differ from measured intakes. Estimates based on the C32 : C31 alkane pair over-estimated intake. Estimates of whole-diet digestibility based on the various ways of estimating intake were all very close to the digestibilities calculated from directly-measured intakes and faecal outputs. It is concluded that the feeding of a known amount of supplement can be successfully used to estimate dietary proportions and hence intakes of diet components, in mixed diets with up to five ingredients, but this approach requires estimates of faecal alkane recovery.
Additional keywords: beeswax, controlled-release device, cottonseed meal, phalaris, ryegrass, subterranean clover, wheat straw.
Acknowledgments
We thank Kim Kleven for her skilled technical assistance. The work was conducted while the senior author was a Visiting Scientist in CSIRO Plant Industry, Canberra.
Boadi DA,
Moshtaghi Nia SA,
Wittenberg KM, McCaughey WP
(2002) The n-alkane profile of some native and cultivated forages in Canada. Canadian Journal of Animal Science 82, 465–469.
Bugalho MN,
Dove H,
Kelman WM,
Wood JT, Mayes RW
(2004) Plant wax alkanes and alcohols as herbivore diet composition markers. Journal of Range Management 57, 259–268.
Charmley E,
Ouellet DR,
Veira DM,
Michaud R,
Duynisveld JL, Petit HV
(2003) Estimation of intake and digestibility of silage by beef steers using a controlled release capsule of n-alkanes. Canadian Journal of Animal Science 83, 761–768.
Chen W,
Scott JM,
Blair GJ, Lefroy RDB
(1999) Using plant cuticular alkanes to study plant-animal interactions on pastures. Canadian Journal of Animal Science 79, 553–556.
Dove H
(1992) Using the n-alkanes of plant cuticular wax to estimate the species composition of herbage mixtures. Australian Journal of Agricultural Research 43, 1711–1724.
| Crossref | GoogleScholarGoogle Scholar |
Dove H, Mayes RW
(1991) The use of plant wax alkanes as marker substances in studies of nutrition in herbivores: a review. Australian Journal of Agricultural Research 42, 913–952.
| Crossref | GoogleScholarGoogle Scholar |
Dove H, Mayes RW
(1996) Plant wax components: a new approach to estimating intake and diet composition in herbivores. The Journal of Nutrition 126, 13–26.
| PubMed |
Dove H, Mayes RW
(2005) Using n-alkanes and other plant wax components to estimate intake, digestibility and diet composition of grazing/browsing sheep and goats. Small Ruminant Research 59, 123–139.
| Crossref | GoogleScholarGoogle Scholar |
Dove H,
Mayes RW,
Lamb CS, Ellis KJ
(2002a) Factors influencing the release rate of alkanes from an intra-ruminal, controlled-release device, and the resultant accuracy of intake estimation in sheep. Australian Journal of Agricultural Research 53, 681–696.
| Crossref | GoogleScholarGoogle Scholar |
Dove H, Moore AD
(1995) Using a least-squares optimization procedure to estimate botanical composition based on the alkanes of plant cuticular wax. Australian Journal of Agricultural Research 46, 1535–1544.
| Crossref | GoogleScholarGoogle Scholar |
Dove H,
Scharch C,
Oliván M, Mayes RW
(2002b) Using n-alkanes and known supplement intake to estimate roughage intake in sheep. Animal Production in Australia 24, 57–60.
Dove H,
Wood JT,
Simpson RJ,
Leury BJ,
Ciavarella TA,
Gatford KL, Siever-Kelly C
(1999) Spray-topping annual grass pasture with glyphosate to delay loss of feeding value during summer. III. Quantitative basis of the alkane-based procedures for estimating diet selection and herbage intake by grazing sheep. Australian Journal of Agricultural Research 50, 475–485.
| Crossref | GoogleScholarGoogle Scholar |
Elwert C, Dove H
(2005) Estimation of roughage intake in sheep using a known daily intake of a labelled supplement. Animal Science 81, 47–56.
| Crossref | GoogleScholarGoogle Scholar |
Elwert C,
Dove H, Rodehutscord M
(2008) Faecal alkane recoveries in multi-component diets and subsequent estimates of diet composition in sheep. Animal 2, 125–134.
Ferreira LMM,
Oliván M,
Garcia U,
Rodrigues MAM, Osoro K
(2005) Validation of the alkane technique to estimate diet selection of goats grazing heather-gorse vegetation communities. Journal of the Science of Food and Agriculture 85, 1636–1646.
| Crossref | GoogleScholarGoogle Scholar |
Ferreira LMM,
Oliván M,
Rodrigues MAM,
Osoro K,
Dove H, Dias-da-Silva A
(2004) Estimation of feed intake by cattle using controlled-release capsules containing n-alkanes or chromium
sesquioxide. Journal of Agricultural Science, Cambridge 142, 225–234.
| Crossref | GoogleScholarGoogle Scholar |
Lee GJ
(2004) Comparison of physical separation and alkane concentrations to estimate the species composition of herbage samples from a pastoral environment. Animal Production in Australia 25, 116–119.
Lewis RM,
Magadlela AM,
Jessop NS, Emmans GC
(2003) The ability of the n-alkane technique to estimate intake and diet choice of sheep. Animal Science 77, 319–327.
Lin L-J,
Luo H-L,
Zhang Y-J, Shu B
(2007) The effects, in sheep, of dietary plant species and animal live weight on the faecal recovery rates of alkanes and the accuracy of intake and diet composition estimates obtained using alkanes as faecal markers. Journal of Agricultural Science, Cambridge 145, 87–94.
| Crossref | GoogleScholarGoogle Scholar |
Mayes RW,
Lamb CS, Colgrove PM
(1986) The use of dosed and herbage n-alkanes as markers for the determination of herbage intake. Journal of Agricultural Science, Cambridge 107, 161–170.
Salt CA,
Mayes RW, Elston DA
(1992) Effects of season, grazing intensity and diet composition on the radiocaesium intake by sheep on re-seeded hill pasture. Journal of Applied Ecology 29, 378–387.
| Crossref | GoogleScholarGoogle Scholar |
Sibbald AM,
Davidson GC, Mayes RW
(2000) Effect of dosing regime on intake estimation using the n-alkane technique in sheep fed pelleted grass meal. Journal of the Science of Food and Agriculture 80, 1206–1210.
| Crossref | GoogleScholarGoogle Scholar |
Smith DG,
Mayes R, Raats JG
(2001) Effects of species, plant part, and season of harvest on n-alkane concentrations in the cuticular wax of common rangeland grasses from southern Africa. Australian Journal of Agricultural Research 52, 875–882.
| Crossref | GoogleScholarGoogle Scholar |
Unal Y, Garnsworthy PC
(1999) Estimation of intake and digestibility of forage-based diets in group-fed dairy cows using alkanes as markers. Journal of Agricultural Science, Cambridge 133, 419–425.
| Crossref | GoogleScholarGoogle Scholar |
