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Context In grazed grassland, the per area output of animal-source products usually declines with decreasing stocking rates because of lower herbage utilisation efficiency. Consequently, nutrient export is larger with increased stocking intensity, which should decrease the productivity in the long term. However, little information is available on long-term productivity of extensive grasslands under varied stocking intensities receiving no input. Aims The effect of stocking intensity was investigated in a long-term grazing trial over 16 years of production. We hypothesised that, despite minimal nutrient export under grazing, no reduction in productivity occurs over long-term periods, but expected an interaction between stocking intensity and year. Method The net pasture productivity was determined in terms of animal performance assessed from Fleckvieh cows grazing in a randomised block design with three replicates in three different stocking intensities (moderate, lenient, and very lenient, corresponding to stocking rates of 1.1, 0.7, and 0.5 livestock unit/ha.year respectively), recorded from 2005 to 2020. Metabolisable energy in GJ/ha.year (MEtotal) provided by the pasture and the livestock unit grazing days/ha.year (LUGD, 1LU = 500 kg) were calculated on the basis of liveweight measurements. Key results The interaction of year and treatment significantly affected LUGD (F = 16.85, d.f. = 30, P < 0.0001) and MEtotal (F = 12.81, d.f. = 30, P < 0.0001) and indicated a cyclic trajectory with increases and decreases in performance over the study years. Overall, the moderate stocking intensity led to and maintained significantly higher performance than did very lenient grazing of up to 60% and 55% in LUGD and MEtotal respectively. However, structural equation modelling indicated a negative temporal trend irrespective of stocking intensity. Conclusions On the basis of existing data of herbage quality and botanical composition from the same experiment, this trend was likely to be a result of nutrient redistribution within pastures that probably changed the botanical composition and grass sward productivity in conjunction with drier years towards the end of this study period. Implications This study showed that productivity in low-input grassland under continuous grazing declines over time irrespective of stocking intensity. Productivity decline in all treatments implies tradeoffs for farmers grazing at lower stocking intensities.

Extensively grazed semi-natural grasslands contribute to a wide range of ecosystem services, including the preservation of biodiversity and provision of livestock feed. Depending on the grazing intensity, cattle are set in motion to fulfill their nutritional needs. In this way, they influence the vegetation composition, while at the same time the foraging behavior is affected by the vegetation. A better understanding of the relationship between grazing intensity and animal behavior is an essential component for strategies to improve the value of semi-natural grasslands and for gaining insights for the development of smart farming technologies. The long-term cattle grazing experiment “FORBIOBEN” with its replicated three paddock-scale (1 ha) grazing intensities [moderate (M), lenient (L), very lenient (VL)] was used to investigate the movement behavior of suckler cows during four grazing periods between 2017 and 2020. For this, pregnant suckler cows (Fleckvieh) were equipped with Vectronics GPS Plus (VECTRONIC Aerospace GmbH, Berlin) collars, which recorded the position of the animals at defined time intervals. The main outcomes were that with an increase in the grazing intensity, the herbage on offer declined and, consequently the herbage allowance. However, the spatial heterogeneity of the herbage on offer decreased with increasing grazing intensity (M &lt; VL) which means that the amount of available herbage was lower but more evenly distributed under moderate grazing. Further, there was a tendency that the moderate grazing intensity was associated with the highest effort of walking compared to lenient and very lenient grazing in three out of four grazing periods. We found a strong (p &lt; 0.001) negative correlation among walking distance vs. herbage variability across all treatments × periods. Consequently, the grazing intensity itself was not a good predictor of walking distances which were mainly a result of the available herbage, its distribution or heterogeneity. Future smart farming livestock management systems will, therefore, likely require interfaces with the grassland growth rates and heterogeneity benchmarks if decisions based on livestock movement should be reliable.

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