Performance of goats and sheep under communal grazing in Botswana using various growth measures

We conducted a survey to evaluate the growth of goats and sheep under communal grazing, and to determine the relationship between weight, heart girth, shoulder height, and body condition score in Kweneng, Central and Kgalagadi districts, Botswana. The same animals were measured on two separate occasions, approximately one month apart, to allow growth rates to be recorded. Significant differences in growth rates between the three case study districts were found for both goats and sheep. Amongst the goats measured, gains in height and weight were significantly greater in the Kweneng district, while gains in heart girth measurement were greatest in the Central district. In the case of sheep, weight gain was significantly higher in the Central and Kgalagadi districts, increases in girth measurement were significantly higher in the Central district, and shoulder height gain was significantly greater in the Kweneng district. Statistical tests were used to determine the relationships between animal weight and the other measures taken for goats and sheep. Heart girth in both goats and sheep was shown to be a significant predictor of weight across all three districts. Likewise, shoulder height proved to be a statistically significant predictor of animal weight for both goats and sheep, across each district. The data therefore suggest that heart girth and shoulder height have potential to act as proxy measurements of weight in both goats and sheep, potentially providing smallholder farmers with a cost-effective way of estimating small-stock productivity

Bush Encroachment Mapping for Africa: Multi-Scale Analysis with Remote Sensing and GIS

Bush encroachment (BE) describes a global problem severely affecting savanna ecosystems in Africa. Invasive species and woody vegetation spread out in areas where they are not naturally occurring and suppress endemic vegetation, mainly grasses. Livestock is directly affected by decreasing grasslands and inedible invasive species which are a result of the process of BE. For many small scale farmers in developing countries livestock represents a type of insurance particular in times of crop failure and droughts. Among that, BE is also becoming an increasing problem for crop production. Studies on the mapping of BE have so far only focused on smaller regions using high-resolution data and aerial photography. But they rarely provide information that goes beyond the local or national level. In our project, we aimed at a continental-wide assessment of BE. For this, we developed a process chain using a multi-scale approach to detect woody vegetation for the African continent. The resulted map was calibrated with field data provided by field surveys and experts in Southern and Eastern Africa. Supervised classification linked field data of woody vegetation, known as BE, to the respective pixel of multi-scale remote sensing data. The regression technique was based on random forests, a machine learning classification and regression approach programmed in R. Hotpots of woody vegetation were further overlaid with significant increasing Normalized Difference Vegetation Index (NDVI) trends which can refer to BE. Secondly, the probability of BE occurrence based on possible identified causes such as fire occurrence, mean annual precipitation rates, soil moisture, cattle density and CO2 emissions was analyzed. By this, possible areas for BE occurrence based on their pre-conditions and risk factors were identified. This approach includes multiple datasets derived from earth observation data to detect BE – a severe and ongoing global problem – at the continental level. Within the study´s duration of seven months, a method to upscale field data to a larger level could be developed. Nevertheless, improvement is needed to provide a reliable continental map on BE. Especially the integration of more field data will be needed which is currently under consideration. The identification of woody vegetation and the probability of its occurrence can help to prevent further ecosystem degradation. Moreover, sustainable land management strategies in these areas can be focused to support pastoralists and their livelihoods in rural areas