2.5.3 Calculating the harvest rate
In this study, the rate of energy acquisition by grazers is quantified
using the product of the harvest rate, as described by Holling’s disc
equation (a type II functional response), and the energy content of the
harvested resources (Brown et al., 2017). The formula for this
calculation is given as
\begin{equation}
H=\frac{\text{αER}}{(1+\alpha R)}\nonumber \\
\end{equation}where\(\ \alpha\) represents the probability of encounter, ℎ denotes
handling time, R symbolizes resource abundance, and E signifies the
energy yield per unit of food. Considering the relatively small size of
the grazing plots (2 hectares), it is assumed that each herbivore
individual encounters resources with uniform probability. However, total
resource availability varies, as the number of sheep units differs
across plots (Fig. 2c). Consequently, the resource abundance per plot
(\(R_{\text{plot}}\)) is modified to:
\begin{equation}
R_{\text{plot}}=\frac{1}{\text{SU}}R\nonumber \\
\end{equation}Here, E is represented by the crude protein percentage (CP%) of
herbage, and resource abundance is indicated by the above-ground biomass
(measured in grams). The handling time (ℎ) is quantified through the use
of tagged sensors that record foraging time (in seconds). This leads to
the revised equation:
\begin{equation}
H=\frac{ER_{\text{plot}}}{(1+R_{\text{plot}})}\nonumber \\
\end{equation}