Abstract:

The Bahima ethnic group of South Western Uganda formerly kept exclusively Ankole
cattle but has recently begun crossbreeding pure Ankole cattle with Holstein Friesian
bulls. Separate herds consisting of pure Ankole and crossbred animals are common.
Given the complexity presented by the emerging production system as well as the
well documented problems usually faced by crossbreds between temperate breeds
and tropical indigenous cattle, a study was undertaken the evaluate the long term
productivity of the emerging production system, identify its constraints and evaluate
some alternative management options. Sixteen farms were selected and data on a
number of parameters were collected. The study revealed that the pastoralists were
largely carrying out continuous grazing with minimal use of paddocks. Hyparrhenia
rufa, Brachiaria spp, Themeda triandra and Chloris gayana were identified as the
most important pasture species whereas Sporobolus pyramidalis and Cymbopogon
afronardus were the most unwanted plant species. Presence of high quality feed
(80%), limited shrubs/weeds (80%) and close proximity to the homestead (30%) were
the main factors considered when allocating cattle genotypes to their respective
grazing landscapes. Crossbred cattle were kept on medium or high quality pastures
whereas Ankole cattle were mostly kept on medium and low quality pastures.
Crossbred pasture had 0.17t/ha DM more than the range grazed by pure Ankole
cattle. The CP content in pastures grazed by pure Ankole (6.30%) was significantly
(P<0.05) lower compared to Ankole-Friesian crossbred grazed range (7.25%). NDF
content was relatively similar (72.82% vs. 69.77%) in both range types. The presence
of Brachiaria spp in the range offers an opportunity for being utilized as hay for
feeding as supplement during dry season. Using a stochastic dynamic simulation
model the dynamics of pastures grazed by Ankole cattle and their Holstein Friesian
crosses and the carrying capacity (CC) of the livestock grazing system was
determined. The overall annual forage production is 3905 ± 72kg/ha. The lowest CC
(5.65 ± 0.75ha/TLU) occurs in long dry season (June to August) while the highest CC
(1.41 ± 0.06ha/TLU) occurs in short rain season (September to November). Annual
carrying capacity ranges between 1.88 and 2.08ha/TLU with an overall mean of 1.95
± 0.04ha/TLU. Sixty three percent of the surveyed farms have stocking rates that are
higher than the CC throughout the year while the rest are overstocked
seasons of the year. The results indicate that CC is dynamic and its variability is
more pronounced within the year than between years. The major point of intervention
in regard to reduction of actual stocking rates could be done in May shortly before the
start of the long dry season. For Ankole pastoral system to be sustainable, the
stocking rate should not go below 1.41ha/TLU.
A comprehensive dynamic simulation model of Ankole pastoral system was
developed to provide a tool for developing and testing alternative management
options for their economic viability and ecological sustainability. The model linked
climate information with dynamic stochastic sub-models for pasture growth, animal
production and economic as well as farmers’ management policies. The model
outputs were compared with field data collected over 3 years. The relative prediction
error (RPE) values for body weight after weaning (7 to 18 months) across both breeds
ranged from 3% to 12% which is below the acceptable limit of 20% and means that
the model predicts post weaning growth with an average error of 7.5%. The model
predicted pasture production and milk yield across seasons with relative prediction
errors of 17.6% and 3.33% respectively. The graph shapes of actual and predicted
average daily milk yield as influenced by season (month of the year) were similar.
Because pasture growth and milk production predictions were acceptable, economic
projections can be made using the model to test different alternative management
options. Using the above model, alternative management options were evaluated that
included reduction on open period and shorter lactation length (1), optimum stocking
rates (2) and restricted breeding season (3). Economic analyses were conducted for
each of the options and some of their combinations. In scenario 1, the average
monthly and annual incomes were higher by 17.3% in the control scenario than in the
scenario 1. Though both scenario 1 and control group had relatively similar average
TLU, the herd value of scenario 1 was 23% higher than the control group. In scenario
2, the optimal stocking rate set at 1.5ha/TLU had a higher (by 2%) income compared
to the control group even though average stocking rate was less by 28.28TLU. Daily
milk yield in the Ankole-Friesian crossbred herd was generally higher (0.3kg) in the
restricted breeding scenario than the year round breeding. The reduction in the open period length for the Ankole herd marginally improved the monthly gross income
compared to the control group but both scenarios resulted in monthly net losses with
exception of a few months when more animals were sold. Adoption of restricted
breeding season would substantially improve the efficiency of the production system
due to more milk harvest as well as improved quality of the herd. The stocking rate
that is ecologically sustainable and economically viable for Ankole pastoral production
system has been found to be around 1.5ha/TLU. A stocking rate below 1ha/TLU is
economically viable but ecologically unsustainable whereas to a stocking rate above
2ha/TLU is ecologically sustainable but leads to under utilization of the rangeland. If
pastoralists are to adopt management methods aimed at reducing calving interval
among the pure Ankole cattle, the benefits would be realized after a period of three
years. Overall, the crossbred herds are much more economical that the pure Ankole
herds. Pastoralists are recommended to drastically reduce the herd sizes for Ankole
herds and only keep small numbers to address the social benefits (payment of
dowry).