Nitrogen efficiency of dairy cattle : from protein evaluation to ammonia emission

Diet optimization contributes considerably to increased nitrogen efficiency of dairy cattle, resulting in reduced nitrogen losses. This thesis focuses on three themes: the potential advances in protein evaluation systems for ruminants, the relationship between dairy cow diet and ammonia emission and the opportunities to monitor ammonia emission from dairy cow barns by application of milk urea content as a practical indicator. Overall, the present work shows that farm management can be aimed at increased nitrogen efficiency of dairy cattle and reduced ammonia emission without compromising other sustainability objectives such as the integral ecological footprint, animal health and farm profitability. </p

Evaluation of an application for dynamic feeding of dairy cows

Dynamic feeding is an innovative application for concentrate feeding of dairy cows. Daily individual settings are derived from the actual individual milk yield response to concentrate intake. This response is estimated using an adaptive dynamic linear model. Optimal daily individual settings for concentrate supply are directed to achieve the maximum gross margin milk returns minus concentrate costs. This response curve plays a key role in the application. The response curve is derived from a mechanistic model for milk production and can also be established empirically from daily milk yield development during early lactation when concentrate supply increase is linear. A test application for dynamic feeding ran for several months in 2008 and results from 145 cows at one farm on 17 December 2008 have been used to demonstrate the variation in individual response. The gross margin, milk returns minus concentrate costs, varied from 2.52 to 26.32 €/day. The estimated response parameters provide insight in variation between individuals concerning the effects of concentrate and base ration intake on daily milk yield. Economical and nutritional aspects can be evaluated for each individual. Individual dynamic feeding towards an economic optimum indicates that excessive changes in individual bodyweighti can be prevented

Ammoniakemissie fors lager na voermaatregelen

De ammoniakemissie vanuit melkveestallen is aanzienlijk terug te dringen door de eiwitvoeding aan te scherpen. Via het melkureumgehalte is goed in beeld te brengen in welke mate de emissie afneemt

Goed voeren bespaart geld en mineralen

Verstandig gebruik van eigen ruwvoer en gerichte aankoop van aanvullend voer maken een efficiënte voeding mogelijk

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

De Marke scherpt voerbenutting aan via mestscore

Deze zogenaamde 'mestscore' heeft inmiddels bijgedragen aan een verdere aanscherping van de voerbenutting

Sturing melkureumgehalte op dierniveau via de voeding

Het Praktijkonderzoek Veehouderij voerde in de winterseizoenen van 1997-1998 en 1998-1999 een viertal voederproeven uit die antwoord moesten geven op de vraag of er variatie bestaat in het optimale melkureumgehalte tussen individuele dieren en in welke mate het melkureumgehalte van individuele dieren valt te sturen door middel van de voeding

Verantwoorde groei op triticale- en graskuil

Jongvee kan uitstekend gevoerd worden met een rantsoen van graskuil en triticale. Een gehele planten silage (GPS) van triticale bevordert een goede penswerking, terwijl graskuil zorgt voor een voldoende eiwitvoorziening