N- en P-excretie melkvee: achtergronden en bronnen voor de berekening

Abstract

De balansmethode om de N-en P-excretie van melkkoeien te berekenen 2.1 Balansberekening als basis 2.2 N en P opname 2.2.1 Kwantificering van de voeropname 2.2.2 Voederbehoefte berekening op basis van de totale netto VEM-behoefte 2.2.3 Voerverbruik en voersamenstelling 2.3 Vastlegging in dierlijke producten 2.3.1 Vastlegging van N en P in melk 2.3.2 Vastlegging dierlijke weefsels

Sensitivity analysis of WUM for calculating mineral excretion : wvaluation of variation in starting values of WUM model on the excretion of nitrogen (N), phosphorus (P) and total potential ammonia nitrogen (TAN) from farm animals in the Netherlands

“…The excretion in the WUM model for dairy cows is not very sensitive to variation in body composition. The same conclusion was drawn earlier by Zom & Kasper (2019). Nonetheless, the data for body composition is quite outdated (Appendix 4).…”

“…In this situation, the extra intake of N and P, that is fully excreted, is a relatively large part of the basal excretion. This conclusion is supported by Zom & Kasper (2019). Similarly, according to the uncertainty analysis performed in by CBS, feed intake and feed composition are relatively uncertain components as it depends not only on animal production levels, but also on the type of farming system (Van Bruggen & Gosseling, 2012).…”

“…Bannink, 2010;Hollander et al, 2014). It was recommended earlier to improve the calculations for VEM requirements (Zom & Kasper, 2019). Since the development of the NEL system, other models have been developed with the aim of estimating feed intake, such as e.g.…”

“…In conclusion, the current estimation error of 2% is fairly good for a model. However, because of the existence of specific feed intake models, the importance of feed intake for the calculation of excretion of N, P, and TAN, as well as the advice of Zom & Kasper (2019), it is prudent to further investigate potential improvement of the estimation of intake in the WUM for this important animal category.…”

Monitoring van methaan-, ammoniak- en lachgasemissies uit melkveestallen : Praktijkmetingen in de periode oktober 2018-oktober 2020

“…Binnen een gewichtsrange van 600 tot 750 kg, kan de emissie 5% hoger of lager uitvallen dan bij een gewicht van 670 kg. Het gehanteerde gemiddelde gewicht van melkgevende dieren is gebaseerd op Zom & Kasper (2019). Gewichtsvariaties binnen een bedrijf zullen niet leiden tot een systematische over-of onderschatting van de CO2 productie.…”