Where
\(\text{TDM}_{p}\) is potential dry-matter production of pasture
(kg/ha/year)
\(\text{AE}_{p}\) is actual evapotranspiration (mm)
F is supper phosphate fertilizer level (for this study, F value =
0 since there is no fertilizer application in the rangeland of the study
location).
Carrying capacity of grasslands
In this study, 30% of the potential utilization rate of grassland used
as proposed by Cossins and Upton (1987)
while 20% use rate of bush/shrub, woodland and the dry forest were
adopted as recommended by Caltabiano
(2006) for Mulga pastures in southern Ethiopian rangeland. About 75%
of woodland, shrub/bush and dry forest flora of tropical Africa are
palatable of browse species for the animal
(Wickens, 1980). Therefore, 0.75
palatability rate of woody, shrub/bush and forest vegetation cover was
used.
The concept of tropical livestock unit (TLU) was used to compute the
carrying capacity of the rangeland. The TLU was used to convert all
livestock types into common denominator using the conversion factor of
0.7 for a cow in the herd, 0.1 for sheep, 0.08 for goat and 1.25 for a
camel. An animal weighing 250 kg with 6.25kg of daily dry matter intake
is considered as one tropical livestock unit
(Houérou & Hoste, 1977). Once the total
forage supply and utilization rate of the rangeland estimated, the
carrying capacity was determined. The information was presented as the
maximum number of animal that the system can carry (TLU/ha/year) and
areas required to graze/browse for specific herds (ha/TLU/years).
\begin{equation}
\mathbf{\text{CC\ }}\left(\mathbf{\text{kg\ of\ live\ weigh}}\mathbf{\ }\mathbf{\text{ha}}^{\mathbf{-}\mathbf{1}}\mathbf{\text{year}}^{\mathbf{-}\mathbf{1}}\right)\mathbf{=}\mathbf{\text{potential\ yield\ of\ TDM}}\mathbf{\ *}\mathbf{\text{usable\ rate\ }}\left(\mathbf{30\%}\right)\mathbf{*\ }\frac{\mathbf{100}}{\mathbf{(2.5*365)}}\nonumber \\
\end{equation}The stocking rate was also determined using a factor for grassland and
20% use factor for bush/shrub; woodland and forestland cover type,
which indicates the total number of livestock on the feeding area for a
specific period (TLU/ha/year).
\begin{equation}
\mathbf{\text{Stocking\ rate\ for\ the\ year\ in\ TLU}}\ \mathbf{\text{ha}}^{\mathbf{-}\mathbf{1}}\mathbf{\text{year}}^{\mathbf{-}\mathbf{1}}\mathbf{=\ }\frac{\mathbf{\text{TLU}}}{\mathbf{T}\mathbf{otal\ grazing/browsing\ area}}\ \nonumber \\
\end{equation}Household survey
The pastoral and agro-pastoral people perception data were collected
using semi-structured questionnaires regarding the interconnection of
climate and land use/cover change on livestock feed availability and
quality. The primary survey data were used to triangulate the
respondent’s perception with the interpretation of land use/cover and
meteorological data. The interviewed household heads were selected using
systematic random techniques, and the sample size was determined using
the simplified formula provided by Yamane
(1967) and Israel (1992) at a 95%
confidence interval and 7% precision level (sampling error). From the
total number of 2,441 livestock owner including camel, 198 household
heads were selected for interview. The interviews were conducted in a
face-to-face approach in the house of respondents, and some are
interviewed at public meeting places or occasionally in other places.
Furthermore, the available livestock feed resources were identified
during the group discussion made with the selected pastoral;
agro-pastoral and livestock feed experts of the study site
n = \(\frac{N}{{1-N(e)}^{z}}\)
where n is sample size, N = total household of selected kebels, e =
precesion level, z= 1.96 (at 95%).
where ni = assigned sample size of kebeles or wealth rank, n = Total
sample size, Ni = Household size of single kebeles or single wealth
group, N = Total household size
Sample Size = n =\(\frac{\mathbf{2441}}{\mathbf{1-2441(0.07)}^{\mathbf{1.96}}}\)