Techniques Used to Determine Botanical Composition, Intake, and Digestibility of Forages by Ruminants

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.

Quantifying the Impact of Different Dietary Rumen Modulating Strategies on Enteric Methane Emission and Productivity in Ruminant Livestock: A Meta-Analysis

“…This evaluation should be accompanied by determining the threshold dosage and source of tannins supplied in separate pulse doses, using a range of carriers in addition to the general approach of including it in a total mixed ration. These carriers should be tailored to the specific feeding systems prevalent in different regions; for instance, grazing is the most common system of rearing ruminants in sub-Saharan Africa [ 30 ]. Therefore, the carriers should be situation specific or should cater for conditions prevalent in a specific area, or, if possible, a range of areas.…”

Estimating nutrient composition and polyphenol concentration using Near-Infrared Spectroscopy (NIRS) in tropical forages

“…Moreover, low-accuracy observations could be linked to insufficient aliphatic (-CH) groups in observed tropical forages (Parrini et al 2017). The structure of fat content varied, such as saturated and unsaturated fatty acids, monoand poly-chain fatty acids, and other triglyceride structures, including phospholipids (Pepeta et al 2022). Problems in CF could be addressed by the various tropical forage characteristics that contained high residual and solid lignin structures depending on the type, species, soil structure, and seasons (Bell et al 2018), showing the possibility for low accuracy in predicting CF content in forage.…”

“…Previous studies have used NIRS to estimate the chemical composition and digestibility of silage (Dias et al 2023;Zicarelli et al 2023), forage chemical composition and nutritive values, and chemical composition of feces (Andueza et al 2017). Another study also used this method for estimating the chemical composition of other feed sources and predicting their potential nutrient digestibility in ruminants and other livestock animals (Nieto-Ortega et al 2022;Pepeta et al 2022). Although chemical analysis using NIRS has shown accurate estimation in monogastric cereal feed with >0.97 predicted correlation values (Nieto-Ortega et al 2022), there is still a significant literature gap.…”

The Potential of Strategies Used to Mitigate Enteric Methane Emissions in Nutrition Studies of Ruminants: A Review

“…Dry matter intake is the principial variable influencing enteric methane emissions in ruminants (Ellis et al, 2007;Hristov et al, 2013) and grazing is the most common and economical system of feeding for herbivores (Pepeta et al, 2022). However, this system is unavoidable subject to seasonal variation of quantity and quality of pastures, which in turn affect production performance and carbon footprint of animals reared under this system.…”