The Importance of Some Sahelian Browse Species as Feed for Goats

Browse species contribute substantially to the availability of feed for livestock in the Sahelian zone of Burkina Faso. This study aimed to identify the most appreciated and utilized browse species, to evaluate their potential for fodder production and nutritive value, and to test the possibility of using them in intensive animal production. In the first experiment the behaviour of cattle, sheep and goats was studied and a survey was undertaken in the study area to estimate the indigenous knowledge of browse species and their utilisation by ruminants. In the second experiment, Acacia senegal, Guiera senegalensis and Pterocarpus lucens, species that were found to be well utilized, were studied by estimating the phenological variation over time and the edible biomass production, total and directly accessible to sheep (0.87 m), goats (1.65 m) or cattle (1.47 m). Biomass production was also estimated using dendrometric parameters. The chemical composition of biomass (leaves and green pods) was determined in the third experiment, followed by measurement of the voluntary intake and apparent digestibility of the leaves and pods (except for G. senegalensis) using goats. Their effect (except for A. senegal leaves) on growth, carcass characteristics and parasite resistance was evaluated in the fourth experiment, feeding the browses ad libitum with a fixed amount of bran and hay and compared with a control diet containing cottonseed cake. The farmers classified the browse species according to their availability, their nutritive value, and several other usages. The feeding activities of all animal species decreased from rainy to dry season, with the decline in fodder availability, while resting and ruminating activities were increasing at the same time. Cattle browsed (leaves and litter) during the whole the study period for around 5% of the time spent on pasture. Sheep and goats made a shift in their feeding activities from grazing to browsing (28% and 52% of the time spent on pasture, respectively, for sheep and goats) when the herbaceous biomass decreased. A. senegal, G. senegalensis and P. lucens started the foliation phase as soon as the rains started, while A. senegal lost leaves earlier. The proportion of accessible biomass was higher for G. senegalensis, but P. lucens had higher total edible biomass. Goats browsing at higher height had more edible biomass at their disposal than cattle and sheep, although the chemical composition was similar for biomass accessible by all three animal species. The crown diameter predicted well the total edible biomass production of the three browse species. The crude protein (CP) content was 114, 157 and 217 g/kg dry matter (DM) and the neutral detergent fibre content 604, 534 and 412 g/kg DM for G. senegalensis, P. lucens and A. senegal, respectively. The highest intake was of the P. lucens leaves diet (864 g) and the lowest of the G. senegalensis diet (397 g). Pods from A. senegal were more consumed than pods of P. lucens. The leaves of A. senegal and P. lucens had similar digestibilities of CP, while A. senegal pods had higher digestibility of all nutrients than P. lucens pods. Goats fed A. senegal pods showed higher growth rate (56 g/day) and the goats on P. lucens pods had the lowest (24 g/day). The carcass weight, dressing percentage and weight of the primal cuts were higher for goats fed A. senegal pods, P. lucens leaves and the control diet. In conclusion, A. senegal pods and P. lucens leaves can be recommended as supplemental feed to poor quality roughages.