Rodrigue V.C. Diogo

Resource use efficiency in urban and peri-urban sheep, goat and cattle enterprises.

Urban livestock husbandry receives growing attention given the increasing urban demand for livestock products. At the same time, little is known about the resource use efficiency in urban livestock enterprises and eventual negative externalities. In livestock production, feeds are an important resource whose nutrients are transformed into products (meat and milk) to generate financial return to the producer. The lack of knowledge on nutrient supply through feed might lead to oversupply with severe environmental impacts. In Niamey, a typical West African city and capital of the Republic of Niger, urban livestock production is constrained by feed scarcity, especially during the dry season. Here, the issue of resource use efficiency was studied in 13 representative and differently managed sheep/goat and cattle enterprises characterized by high and low feed inputs, respectively, during a period of 28 months. Nitrogen (N), phosphorus (P) and potassium (K) inflows into each farm through livestock feeds and outflows through manure were determined using a semi-structured questionnaire; interviews were accompanied by regular weighing of feed supplied and dung produced. Live weight gain (LWG) and efficiency of conversion of total feed dry matter offered (kg TDMO/kg LWG) were computed along with nutrient balances (NBs) per metabolic body mass (kg0.75). NBs (per kg0.75/day) in the high-input (HI) sheep/goat enterprises were +1762.4 mg N, +127.2 mg P and +1363.5 mg K and were significantly greater (P < 0.05) than those in low-input (LI) units (+69.1 mg N, -98.3 mg P and +16.5 mg K). In HI cattle enterprises, daily balances averaged +454.1 mg N, +40.1 mg P and +341.8 mg K compared to +34.4 mg N, -9.0 mg P and +68.3 mg K (P > 0.05) in LI cattle systems. All systems were characterized by poor conversion efficiencies of offered feed, which ranged from 13.5 to 46.1 kg TDMO/kg LWG in cattle and from 15.7 to 43.4 kg TDMO/kg LWG in sheep/goats. LWG in HI sheep/goats was 53 g/day in the rainy season, 86 g/day in the hot dry season and 104 g/day in the cool dry season, while HI cattle lost 79 g/day in the hot dry season and gained 121 g/day and 92 g/day in the cool dry and rainy seasons, respectively. The data indicate that there is nutrient wasting and scope for improvement of feeding strategies in Niameys livestock enterprises, which might also decrease nutrient losses to the urban environment.

Temporal and spatial changes of land use in rare metal mining areas of Rwanda

Abstract To analyse the effects of mining activities on land use and land cover changes in the Gatumba mining district of Rwanda, aerial photos from 1958, 1974 and 2009 were classified using segmentation approaches. Drastic land cover changes were observed in the study region with the highest mining activities in 1974. From 1958 to 1974, woodland decreased by 54% and cropland increased rapidly. From 1974 to 2009 the process reversed, with woodland increasing while cropland decreased by 51%. This was mainly due to enforced legal regulations of the Government of Rwanda to control land degradation and a decline of mining activities.