Economic damage caused by spittlebugs (Homoptera: Cercopidae) in Colombia: A first approximation of impact on animal production in Brachiaria decumbens pastures

Using a simulation model as an analysis tool, the economic impact of spittlebugs in pastures of Colombia was quantified in terms of animal production. Three levels of abundance (10, 25, 50 adults/m2 ) and farm area affected (25, 50, 100%) were evaluated using data obtained in Brazil for Notozulia entreriana (Berg) on Brachiaria decumbens Stapf. The model considered dual-purpose production systems in two contrasting ecosystems: (1) the dry tropics, characterized by a well defined, 6-month rainy season and (2) the humid tropics, characterized by uniform rainfall distribution throughout the year. Compared to healthy pastures, stocking rate, milk and meat productivity decreased 1-8, 8-34 and 38-54%, respectively, at low, intermediate and high abundance levels, depending on farm area infested. The cost of producing milk and meat increased 0-4, 3-16 and 18-30% at the same infestation levels, causing net income to decrease 3-16, 17-69 and 67-100%. At the regional level, economic damage in the 1,140,000 ha sown to grasses susceptible to spittlebugs in the humid tropics of Colombia ranged from US$7-25, 28-36 and 39-47 million/yr. In the 4,720,000 ha of susceptible grasses in the dry tropics, economic damage was US$33-118, 132-175 and 228-273 million/yr. The investment required to develop grass varieties resistant to spittlebugs and adapted to soils with low to intermediate fertility (US$6 million over 12 yr) is low compared with the economic damage caused by spittlebugs in Colombia, and therefore presents a major economic incentive for support of research on varietal improvement and spittlebug management

Simulation of costs and benefits of supplementing milking cows with legumes during the dry season in two hillside regions of Nicaragua

Objectives of this study were to compare costs and expected benefits of feed supplementation in cattle with alternative shrub legumes during the dry season using as a case study the hillsides of Central Nicaragua. The information used was gathered in a survey of 32 farms in the states of Boaco and Chontales in Central Nicaragua. The survey was designed to determine herd structure, land use patterns, milk and beef production, and use of inputs for animal nutrition, in order to estimate production, reproductive parameters and employment of family/contracted labor, as well as indicators of profitability of the alternatives under study. To calculate the economic return to the investment in alternative forages, a simulation model that applies optimization techniques through linear programming, implemented as a spreadsheet, was used to perform an ex ante evaluation of the costs and benefits of different land use alternatives and of interactions between technological components and biological productivity. The model compares the costs and benefits of the traditional feeding system versus an improved feeding system. The traditional system consists of grazing naturalized pastures (Hyparrhenia rufa) during the rainy season. In the dry season producers supplement the herd with small areas of king grass (Pennisetum spp.). The improved feeding system consists of establishing forage legumes for dry season feeding as a supplement to replace king grass during the dry season. Supplements to evaluate are the shrub legume Calliandra calothyrsus as partial replacement of the herbaceous high quality legume Vigna unguiculata, commonly known as Cowpea. Under the new feeding system, herd size can be increased by 60% due in part to the increase in stocking rate as well as to the increase in the quality of the diet offered with higher protein content. This increase in herd size raises both milk and beef output that generates an increase in farm income by 1.8 times more (i.e., from $1,314/farm/yr to$2,386). The economic return to family labor is increased by 20% to $ 5.26/day equivalent to 2.3 times higher than the local wage rate. The adoption of Vigna (Cowpea) after the harvest of maize/beans and a shrub legume as Calliandra to replace king grass seem to have the potential to significantly improve the productivity in smallholder farms. with the resulting increase in the economic return to family labor