A comparison of in situ and in vitro methods to estimate in vivo fermentable organic matter of forages in ruminants

Farmers in five districts of north-eastern Uganda were interviewed to generate information on sweet potato production and constraints, with emphasis on damage by millipedes. Participatory rural appraisal methodology was used to interview 148 farmers. The peak period of planting sweet potato was from the end of May till the beginning of July in order to produce dried form food (amukeke) for storage in the dry season, which sets in around November. Vine cuttings were usually planted on mounds and weeding was mostly done only once. Osukut, Araka Red and Araka White were the most popular varieties. Many respondents obtained planting material from volunteer plants. Separation of plots over time and in space was often not practised. Sweet potato crop rotations were diverse. Millet, groundnut and maize were commonly grown after sweet potato. Cassava, sweet potato, groundnut and maize are host crops for millipedes and were often grown in succession. Millipede incidences were not statistically different for the three agro-ecological zones of north-eastern Uganda, but depended on the frequency of millipede hosts (including sweet potato) in the crop rotations. Groundnut planted after sweet potato had high levels of millipede attack. Millipede incidence was often associated with the incidence of weevils. The results of this inventory show that most farmers consider millipedes as a pest of sweet potato and other major food and cash crops, but that many farmers lack the knowledge to control them

Estimation of the duodenal flow of microbial nitrogen in ruminants based on the chemical composition of forages: a literature review

The objective of this study was to evaluate the estimation of the duodenal flow of microbial nitrogen (N) in ruminants fed forage only, per kilogram of dry matter (DM) intake, which is the yield of microbial protein (YMP). The estimation was based on the chemical composition of forages. A data file of 62 observations was collected from in vivo studies on cattle and sheep fed diets with forage only. A statistical analysis of YMP was conducted with neutral detergent fibre (NDF), crude protein (CP), non structural carbohydrates (NSC), group of forage species (legumes or grasses), method of conservation, physical form of presentation, level of DM intake, animal species, methodology and references as parameters. After a stepwise regression, CP was significant and the most important predictor. NSC or the method of conservation had an extra effect on YMP. On the basis of these three parameters the best fit equations were found and the influence of all parameters on YMP were discussed. Using the data file of this study, the prediction of YMP from the PDI-system was also validated. The statistics of the validation of the PDI prediction were similar to the statistics of the equations from this study. In conclusion, the chemical composition of forages, with or without the method of conservation, is a poor indication for the duodenal flow of microbial N (g $\cdot$kg -1 DM intake) in ruminants fed diets with forages only