During the summer period, grazing cattle therefore have to invest time to select herbage and are also forced to use overripe parts of the pasture. As a result, performance of the individual animal decreases (Baumont et al. 2000). Towards the end of the grazing period, in late summer/autumn, the relation CB-5083 purchase between herbage on offer (standing crop) and intake by the grazing cattle synchronizes again. At this time, the variability in quality and sward height is reduced, causing less need for the animal

to select. This will allow, weather conditions permitting, a moderate increase in animal performance during that period. Overall, preferred patches are defoliated very frequently and experience the same pressure as on pastures with high grazing intensity. However, other pasture areas are hardly influenced by the animals during long parts of the grazing season. Here, competition between species will drive diversity development. Usually, farmers would choose to cut or mulch surplus vegetation at the end of a grazing season. Fig. 1 Schematic overview of the phases of developments and of the interactions of grazing cattle and sward structure

under conditions of selective grazing on extensively grazed grassland The type of grazing animal has important implications for phytodiversity, especially due to different feeding preferences. The mechanical prerequisites for selective grazing and their differences between animal species Thalidomide have already been discussed above. Requirements of the animals for energy and quality further determine their influence on the vegetation. Impacts due to treading and excretion vary between species. Treading is especially important where Selleck SB525334 a lot of weight is carried on a small area or where animals are very

mobile. Apart from small differences in nutrient retention between animal species, excretion mainly differs with respect to the amounts excreted at a given time and the distribution of excreta patches. Thus, depending on the size of the pasture, Selleck Cyclosporin A horses may show latrine behaviour, excreting always at the same points (Lamoot et al. 2004), while cattle may distribute excreta more evenly over the pasture area (White et al. 2001). This has implications for the nutrient return to the plants and mining of nutrients versus accumulation at other places. Interestingly, the choice of the breed, apart from size and weight restrictions, seems generally to be of less importance in cattle (Fraser et al. 2007; Isselstein et al. 2007), but effects have been reported for sheep and goats (Osoro et al. 2007, 2002). Larger breeds might achieve better performance rates but have higher requirements for maintenance (protein, energy, minerals etc.). Different effects of grazers on swards are sometimes utilized in co-grazing. Thus, grazing by goats has been found to have positive effects on following sheep grazing, as the proportion of clover in the pasture increased (del Pozo et al. 1998).