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The use of the alkane technique to estimate diet selection of sheep grazing grass–clover/heather–gorse vegetation communities
Author(s) -
Ferreira Luis MM,
Oliván Mamen,
Celaya Rafael,
Garcia Urce,
Rodrigues Miguel AM,
Osoro Koldo
Publication year - 2006
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2717
Subject(s) - lolium perenne , trifolium repens , calluna , grazing , herbaceous plant , composition (language) , biology , zoology , alkane , feces , botany , agronomy , ecology , poaceae , ericaceae , philosophy , biochemistry , catalysis , linguistics
The n ‐alkane technique was evaluated for estimating the diet composition of sheep grazing in heathlands. Six dietary treatments, composed by different proportions of herbaceous ( Lolium perenne and Trifolium repens ) and woody species ( Erica umbellata, Erica cinerea, Calluna vulgaris and Ulex gallii ) were offered to 24 sheep housed in metabolism crates. Diet composition was estimated from alkane concentrations in diet and faeces, by least‐squares procedures, using all available alkanes (C1) from C 25 to C 33 , or only those with higher concentration (C2): C 27 , C 29 , C 30 , C 31 and C 33 . Additionally, the effect of applying mean treatment faecal recoveries (R1), mean faecal recoveries of all experimental diets (R2) or no faecal recovery correction (R3) was studied in both selections of alkanes (C1 and C2). No significant differences were observed between the use of all alkane information (C1) or limited number of alkanes (C2) in the diet composition calculations. There were no significant differences between measured proportions of dietary components and those estimated with procedures R1 and R2. In contrast, the proportions calculated with R3 procedure differed significantly ( P < 0.05) from the measured proportions, overestimating feeds with higher content of long chain n ‐alkanes. The results indicate that correction of faecal alkane concentrations to allow for incomplete faecal recovery is necessary in order to obtain accurate estimates of diet composition, using mean treatment faecal recoveries (R1) or mean faecal recoveries of all experimental diets (R2). Copyright © 2006 Society of Chemical Industry