Assessment of very long-chain fatty acids as complementary or alternative natural fecal markers to n-alkanes for estimating diet composition of goats feeding on mixed diets1

Abstract

This study aimed to assess the use of very long-chain fatty acids (VLCFA) as an alternative or a complement to n-alkane markers for estimation of diet composition of goats fed 7 different diets, composed of different proportions of herbaceous (Lolium perenne and Trifolium repens) and heathland woody species (Erica umbellata, Erica cinerea, Calluna vulgaris, Erica arborea, and Ulex gallii), in a metabolism study. Diet composition was estimated from VLCFA (i.e., C(22) to C(34)) and alkane (i.e., C(25) to C(33)) concentrations in diet and feces, by least squares procedures. For all plant species VLCFA concentrations were greater than their alkane concentrations, especially for the herbaceous species and U. gallii. In general, fecal recovery of both markers was incomplete and increased in a curvilinear (P < 0.001) fashion with carbon-chain length. The plants comprising the diets had a significant effect (P < 0.001) on fecal recovery of VLCFA and alkanes. Diet composition estimates based on VLCFA alone were less accurate (P = 0.013) than those obtained using alkanes alone. Combination of VLCFA and alkane data resulted in the most accurate (P < 0.05) estimates, indicating an increase on the discriminatory power among plant species. Use of uncorrected fecal marker concentrations provided the poorest estimates of diet composition, and use of individual recovery data and mean fecal recovery data of the dietary treatment yielded the most accurate ones. Results obtained in this study show that VLCFA have potential to be used as diet composition markers along with alkanes.

Application of long-chain alcohols as faecal markers to estimate diet composition of horses and cattle fed with herbaceous and woody species

“…For cattle, a positive association between CCL and LCOH FR was found. A similar trend was observed for horses and cattle when using LCFA (Ferreira et al, 2010) and alkanes (Ferreira et al, 2007 and2009a), and also in other ruminant species when studying LCOH (Ali et al, 2004;Dove and Charmley, 2008), LCFA (Ali et al, 2004;Ferreira et al, 2009b and and alkanes (Dove and Mayes, 2005;Ferreira et al, 2005 and2009a;Charmley and Dove, 2007). These data indicated that markers behave differently in the gastro-intestinal tract of ruminant and nonruminant species, and suggest that the disappearance of those with the shorter carbon-chain in the gut of ruminants occurs to a greater extent than in non-ruminants.…”

“…It should be pointed out that the superiority of LCOH markers found in this study, may be situation dependent and the selection of one type of marker should also be based on the marker concentrations in the possible diet components and its capability of discriminating between them (Ferreira et al, 2012), discarding types of marker with very low concentrations in plant species within the diets. It is usually suggested that markers with very low concentrations have greater measurement errors in their analytical determination (Dove and Mayes, 2005) and their utilization may result in less accurate estimates of diet composition (Charmley and Dove, 2007;Ferreira et al, 2009b).…”

“…Thus, their application may result in less accurate estimations of both diet selection and feed intake (Ferreira et al, 2007). To overcome these limitations, other epicuticular wax components such as long-chain fatty acids (LCFA) (Ali et al, 2005;Ferreira et al, 2009b;Lin et al, 2009), and long-chain fatty alcohols (LCOH) (Ali et al, 2004;Ferreira et al, 2012 and2015) have been suggested as additional markers to estimate diet composition of small ruminants. In fact, their utilization may increase the accuracy of estimates by providing additional discriminatory information to that supplied by alkanes.…”

The potential use of n-alkanes, long-chain alcohols and long-chain fatty acids as diet composition markers: indoor validation with sheep and herbage species from the rangeland of Inner Mongolia of China

“…The accuracy of diet composition estimates as a whole was assessed using the Kulczynski similarity index (KSI), which calculates the overlap between observed and estimated diet composition using different markers and different sets of faecal recovery correction, as follows (Kerbs, 1989;Ferreira et al, 2009a):…”

“…To date, these studies have been conducted by feeding known mixtures of two to five components to livestock, based on alkanes alone (Charmley and Dove, 2007;Lin et al, 2007;Ferreira et al, 2009b), and different combinations of alkanes and alcohols (Dove and Charmley, 2008) or alkanes and acids (Ferreira et al, 2009a). Moreover, the studies for evaluating the potential use of alkanes, alcohols and acids as diet composition markers were based on even more simple diets with three components (Ali et al, 2005;Lin et al, 2009b).…”