Abstract

The accuracy of the double η-alkane technique to estimate dry matter intake (DMI) of red deer (Cervus elaphus) fed fresh cut perennial ryegrass-based pasture (Lolium perenne cv Nui) and narrow-leaved plantain (Plantago lanceolata cv Ceres Tonic) was determined in a cross-over experiment involving five adult castrated stags housed in metabolism cages. A strong positive linear relationship between actual and estimated DMI was obtained for pasture when using both C31 and C33 (C31 R2 = 0.94; P < 0.01; C33 R2 = 0.92; P < 0.01) and plantain for C31 (R2 = 0.80; P < 0.04), but not for C33 (R2 = 0.49; P < 0.19). However, the predicted DMI of deer using the η-alkane technique was underestimated up to 27.6% for deer fed ryegrass-based pasture and overestimated up to 17.2% for deer fed plantain when compared with actual DMI. The discrepancies between actual and predicted DMI could have been partly due to a difference of 26% between faecal recovery rates of odd and even-chain alkanes with pasture feeding and 12% with plantain feeding. This suggests that the η-alkane technique may not be appropriate for estimating DMI of ruminants grazing New Zealand fresh forages, especially when comparisons between forage species are required.

NM, Swainson, SO Hoskin, H Clark, and M Krause

Proceedings of the New Zealand Society of Animal Production, Volume 65, Christchurch, 23-28, 2005