Steeds meer inzicht in de celwand. Oogsttijdstip, groeiomstandigheden en ras bepalen celwandverteerbaarheid maïs

Na jaren van veredeling op het kolfaandeel in de maisplant krijgt nu ook de celwandverteerbaarheid van de restplant meer aandacht. Waarom is de ene celwand wel verteerbaar en de andere niet? Onderzoek door ASG en Wageningen UR moet nieuwe inzichten geven voor verdere veredelin

Modelling Animal Systems Paper: Update of the Dutch protein evaluation system for ruminants: the DVE/OEB2010 system

In the current Dutch protein evaluation system (the DVE/OEB1991 system), two characteristics are calculated for each feed: true protein digested in the intestine (DVE) and the rumen degradable protein balance (OEB). Of these, DVE represents the protein value of a feed, while OEB is the difference between the potential microbial protein synthesis (MPS) on the basis of available rumen degradable protein and that on the basis of available rumen degradable energy. DVE can be separated into three components: (i) feed crude protein undegraded in the rumen but digested in the small intestine, (ii) microbial true protein synthesized in the rumen and digested in the small intestine, and (iii) endogenous protein lost in the digestive processes. Based on new research findings, the DVE/OEB1991 system has recently been updated to the DVE/OEB2010 system. More detail and differentiation is included concerning the representation of chemical components in feed, the rumen degradation characteristics of these components, the efficiency of MPS and the fractional passage rates. For each chemical component, the soluble, washout, potentially degradable and truly non-degradable fractions are defined with separate fractional degradation rates. Similarly, fractional passage rates for each of these fractions were identified and partly expressed as a function of fractional degradation rate. Efficiency of MPS is related to the various fractions of the chemical components and their associated fractional passage rates. Only minor changes were made with respect to the amount of DVE required for maintenance and production purposes of the animal. Differences from other current protein evaluation systems, viz. the Cornell Net Carbohydrate and Protein system and the Feed into Milk system, are discussed

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