Abstract:
The botanical and chemical composition of diets consumed by ruminants is different from
the composition of plant species available in the rangeland or pastures on which they graze. Exploring
alternative and improving existing methods of estimating botanical composition (diet selection)
is imperative in advancing sustainable feeding practices in extensive production systems. The
ability to predict the intake and digestibility of the diet consumed is important in designing grazing
management for different feeding systems as well as supplementation strategies. This facilitates
the efficient use of feed resources for optimal animal performance. This review assesses the merits,
limitations, and potential advancements in techniques used to estimate botanical composition, forage
intake, and digestibility in ruminants. Supplements containing sufficient quantity and identifiable
n-alkanes can be used to determine the total forage intake in grazing ruminants without dosing
the animals with synthetic even-numbered n-alkanes. When the botanical composition, intake, and
digestibility of diet are estimated using internal markers, the results should be validated with those
of faecal near-infrared reflectance spectroscopy (NIRS) or plant cuticular compounds to enhance
the prediction accuracy. This should be done to determine the degree of error in the use of internal
markers. Conclusively, the use of internal markers with automated solver routine software is a
prudent approach to predicting botanical composition due to the analytical ease of the markers
involved and the associated model assumptions.
