Validating the alkane pair technique to estimate dry matter intake in equids

Abstract

The estimation of dry matter intake (DMI) using the alkane pair technique has been validated in ruminants, but not in equids. The current paper reports the finding of three comparative validation studies carried out using a total of 12 cattle, 29 donkeys and 10 horses during which directly measured intake was compared to estimated intake using the alkane pair technique. Two methods were developed to dose the even chain alkanes that were used as external markers. Study I, carried out in Zimbabwe, compared the accuracy of estimated intake with measured intake in cattle and donkeys using hexatriacontane (C36) as the external marker. Studies II and III were carried out in the UK with horses and donkeys and compared the accuracy of estimated intake with measured intake using dotriacontane (C32) as the external marker. Study III also tested the effect on the accuracy of intake estimates of two marker dosing levels (mean daily dose of 224 mg per animal and 448 mg per animal) and two dosing frequencies (2× and 3× daily). Twice daily dosing of even-chain alkane at the lower dose level provided an estimate of DMI similar to that obtained by thrice daily dosing at this low level. The higher dose level given twice daily tended to produce large variation in faecal concentrations of dosed even-chain alkanes, this variation was reduced when dosing frequency was increased to thrice daily. The accuracy of estimated intake improved progressively as the number of faecal sampling days was increased from one to six with no significant difference between estimated intake based on day 5 or 6 of faecal sampling. The results of all three studies indicate that the alkane pair technique provides a robust method of estimating intake in equids with no significant difference between measured and estimated values in all but one case. Using C31 as an internal marker provided a more accurate estimated intake than using C33 as the internal marker in all cases. Faecal recoveries of alkanes in equids do not appear to show the same influence of carbon chain length that has been observed in ruminant studies. © 2007 Cambridge University Press

Comparison of long-chain fatty acids and alkanes as markers to estimate diet composition of equines and cattle consuming heathland vegetation species

“…Although to the authors' knowledge there are no published faecal recovery data of LCFA in equines, results obtained for alkanes in nonruminant species (Sehested et al, 1999;Ordakowski et al, 2001;Monks et al, 2005) showed absence of any systematic relationship between chain length and the faecal recovery. By contrast, Smith et al (2007) and Ferreira et al (2009b) observed an increase of alkane faecal recovery with alkane carbon-chain length in equids.…”

n-Alkane and long-chain alcohol recovery in moose (Alces alces), a browsing herbivore

“…These include very long-chain fatty acids (VLCFA), long-chain alcohols (LCOH), and n-alkanes. These hydrocarbons have been recently used for predicting diet composition of herbivores (Dove et al 1996;Ali et al 2005; Dove and Mayes 2006), measuring forage intake (Ferreira et al 2004;Dove and Mayes 2005;Smith et al 2007;Hu et al 2014), and digestive tract passage rate (Hatt et al 2002;Dove and Mayes 2006;Giraldez et al 2006). n-Alkanes, LCOHs, and VLCFAs can be readily extracted from plants using either a process of saponification and esterification (Dove and Mayes 2006) or accelerated solvent extraction (ASE; Carnahan et al 2013) , then analyzed using gas chromatography.…”

Use of n-alkanes for estimation of voluntary intake and digestibility in donkeys (<i>Equus asinus</i>)

“…The alkanes pair technique (APT) was recently, developed and validated in a variety of ruminant species to estimate DMI in grazing animals (Mayes et al, 1988). To a limited extent this method has also been validated in horses by Ordakowski et al (2001) and most recently in donkeys fed temperate grasses by Smith et al (2007). The APT uses a naturally occurring odd-chain alkane (usually C31 or C33) and a dosed adjacent even chain alkane (usually C32) to estimate DMI (Mayes and Dove, 2000).…”