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

The research investigates the use of long-chain alcohols (LCOH) as markers to estimate the diet combination of horses and cattle eating mixed grass and woody plants. Combining these markers with alkanes and long-chain fatty acids (LCFA) improved the accuracy of the estimated dietary intake and any errors in faecal recovery were accounted for to refine these estimates.

Understanding the Study

• The study involved 12 mature crossbreed mares and six non-lactating cows of the Asturiana de los Valles breed. Their diets varied in proportions of ryegrass (a common herbaceous plant species) and woody species (Ulex gallii and heather).
• The aim was to determine if long-chain alcohols (LCOH), when combined with other indicators, could be used to provide a more accurate estimate of the animals’ diet composition.
• The researchers also sought to understand how successfully these LCOH markers were recovered from the animals’ faeces. This is important as incomplete faecal recovery can cause underestimation or overestimation of the actual food intake.

Key Findings

• The results unveiled significant variance in LCOH profiles between plant species, suggesting that these markers provide unique information, in addition to the data available from other indicators, such as alkanes and LCFA.
• The LCOH markers were not entirely recovered in the faeces of either animal species. The recovery rate of these markers in cattle tended to increase in a linear manner with carbon-chain length, while in horses, it showed a curvilinear relationship.
• The combination of LCOH, LCFA, and alkanes provided more accurate estimates of the diet. Further, accounting for incomplete faecal recovery with corrections to the LCOH concentrations improved the estimation accuracy of the diet composition for both horses and cattle.

Implications of the Study

• The study findings underscore the importance of identifying and using multiple dietary markers to accurately assess the diet composition of grazing animals. This could enhance the understanding of livestock diet, essential for the development of better diet strategies for farm animals.
• While the study only focused on horses and one breed of cattle, the conclusions could be utilized to help other animal researchers and farmers better assess diet intakes for different grazing animals.
• As the method proposed gave more accurate estimates, it can be a potentially valuable tool for nutritional, ecological, and environmental studies related to livestock.