ABSTRACT

A high price for milk during the era of milk quotas has encouraged dairying systems with high inputs of chemical fertilisers, concentrate feeds and mechanised methods for maize silage production at the expense of grazing and the use of grassland. These trends were largely reinforced firstly by the convenience of managing herds indoors particularly with cows calving in autumn and fed with maize silage and secondly by the inability of grazing to maximise individual milk yield. As a result, the number of cows kept indoors for all or part of the herbage growing season has increased considerably in many European countries (Van den Pol-van Dasselaar et al., 2008) and the productivity of milk per cow has dramatically increased. Today, high genetic merit Holstein cows are able to produce more than 10 000 kg milk per lactation in high-input farming systems, but it is not feasible to produce such amount of milk from the cows by keeping them to grazing alone (Kolver and Muller, 1998). Similar trends have also been observed for beef and sheep meat production, although less marked than for dairy production. The productivity per hectare of land used in Europe has also increased, at least when the land virtually imported with soybean meal is not considered. Consequently, the area of grassland in Europe has been

significantly reduced during the last 30 years. According to Eurostat (2010a,b), in the EU-6, these losses are estimated at about 7.1 million ha between 1967 and 2007 that is, about 30% of the value recorded in 1967, and this reduction in grassland area has been tightly correlated with the reduction in the total number of cows (Peyraud and Peeters, 2016), which in turn is a consequence of the increase in milk yield per cow in the context of the milk quota system. However, these changes have had major drawbacks due to the decrease in associated ecosystem services provided by permanent grassland (MEA, 2005; Peeters, 2008; Huguenin-Elie et al., 2017); the opening of N cycles, leading to the degradation of water quality in regions specialising in intensive livestock production (Peyraud et al., 2014); and increased dependency of European livestock on soya imports (Galloway et al., 2008).