Grazing experiment at Schothorst Feed Research
A grazing experiment was carried out at Schothorst Feed Research from June until September 2016. This experiment is part of a larger project were the main research topic is the combination of grazing and reduction of ammonia emissions. This project was financed by the Ministry of Economic Affairs and executed in collaboration with NMI-Agro.
Currently, there is a lot of attention for whether dairy cows get access to pasture or not. Farmers in the Netherlands can receive a bonus for the milk of cows which have access to pasture for at least 6 hours per day and 120 days a year. Ammonia emissions from dairy farms can also be reduced when cows have access to pasture. Ammonia emission is difficult to measure, especially with cows on pasture. NMI-Agro developed an ammonia emission model to predict the ammonia emission based on ration components, period access to pasture, animal features and housing features.
In this experiment 48 cows had either 5 or 10 hours access to pasture and received two different concentrate strategies: Control or Synchronous. In the Synchronous feeding treatment, energy and protein from concentrate was divided over the day to synchronize energy and protein fermentation in the rumen. The effects of grazing duration and synchronisation on milk production and composition was followed for 17 weeks. Also 20 cows were equipped with activity sensors to the neck and leg.
In ration optimisation grass intake from pasture is often an unknown factor. In this experiment, NMI-Agro conducted, together with students, a lot of measurements on grass intake and grass quality. In 14 measurement periods of 3, 4 or 5 days grass yield before grazing and after grazing was measured and grass intake was calculated. The grass intake data will be compared to the behavioural data from the neck sensor to study the potential of predicting grass intake from activity sensors. Also several sensors to estimate grass yield and nitrogen content were tested, for example, the pasture height meter and CropScan. All these measurements asked for a lot of labour and flexibility, because with grazing we have to deal with the weather conditions.
Next to the grazing experiment, a digestibility trial was carried out to measure DM, CP, ZET and NDF digestibility. The rations from pasture were fed to individual cows trough Calan gates and cows had either 5 or 10 hours access to fresh cut grass. At this moment, data is processed and prepared for statistical analyses or model optimization. The results of the grazing experiment will be used to optimize our advice concerning grazing, production and ammonia emission.