Content and pattern of n-alkanes in some native forage species from NE Mendoza, Argentina

ALLEGRETTI, L.; EGEA, V.; BAKKER, M.L.; PAEZ, S.; SARTOR, C.

BIOCELL

Año: 2008

0327-9545

Estimates of intake and diet composition to understand the foraging behaviour of Criollo goats in the rangelands of NE Mendoza are required but scarce. The n-alkanes present in forages may be used as markers to estimate diet composition. The objective of this preliminary study was to analyse the content and pattern of n-alkanes in some native forage species, to evaluate its potential to estimate diet composition in goats. Six species: Prosopis flexuosa (PF), Capparis atamisquea (CA), Atriplex lampa (AL), Mimosa ephedroides (ME), Bulnesia retama (BR), Tricomaria usillo (TU) were collected in March 2007, plant parts (current season´s leaves, stems or fruits) were analysed for odd n-alkane (C23 to C35) content (mg.kgDM-1) by capillary GC, and the pattern of n-alkanes (% of each in total) was calculated. The patterns of n-alkanes had some contrasts among species and plant parts. More abundant n-alkanes in all species were C27, C29, C31 and C33; but C29 was high in ME fruits (72%), PF stems (70%) and leaves (61%) and TU leaves (61%), stems (54%) and fruits (52%), C31 in BR stems and fruits (74%) and ME stems (54%), and C33 in CA leaves and stems (68%). CA had also a comparatively high proportion of C35 (8%), which is a rare finding in forages. AL had C27, C29 and C33 accounting for ca. 25-30% of total each. A comparatively high proportion of the even n-alkane C28 (to confirm) in PF would allow the use of this compound as an extra marker to separate this species from others. n-alkanes present in forages may be used as markers to estimate diet composition. The objective of this preliminary study was to analyse the content and pattern of n-alkanes in some native forage species, to evaluate its potential to estimate diet composition in goats. Six species: Prosopis flexuosa (PF), Capparis atamisquea (CA), Atriplex lampa (AL), Mimosa ephedroides (ME), Bulnesia retama (BR), Tricomaria usillo (TU) were collected in March 2007, plant parts (current season´s leaves, stems or fruits) were analysed for odd n-alkane (C23 to C35) content (mg.kgDM-1) by capillary GC, and the pattern of n-alkanes (% of each in total) was calculated. The patterns of n-alkanes had some contrasts among species and plant parts. More abundant n-alkanes in all species were C27, C29, C31 and C33; but C29 was high in ME fruits (72%), PF stems (70%) and leaves (61%) and TU leaves (61%), stems (54%) and fruits (52%), C31 in BR stems and fruits (74%) and ME stems (54%), and C33 in CA leaves and stems (68%). CA had also a comparatively high proportion of C35 (8%), which is a rare finding in forages. AL had C27, C29 and C33 accounting for ca. 25-30% of total each. A comparatively high proportion of the even n-alkane C28 (to confirm) in PF would allow the use of this compound as an extra marker to separate this species from others.