Effects of grazing and precipitation on herbage production, herbage nutritive value and performance of sheep in continental steppe

Abstract

The present study highlights the effects of sheep grazing and precipitation on herbage and animal performance in a grazed steppe of Inner Mongolia. Experimental data were collected during grazing periods of four consecutive years (2005–2008), and effects were analysed across a gradient of seven grazing intensities. Variation in annual precipitation, reflected by the effect of ‘year’, was the major factor affecting herbage; i.e., the production and nutritive value of herbage increased with increasing precipitation. Herbage parameters were also affected by grazing intensity, as herbage production (HP) and herbage nutritive yields decreased, while herbage nutritive values increased with increasing grazing intensity. The grazing‐induced decrease in herbage nutritive yields suggests that decreases in HP offset the positive effect of grazing on the nutritive value. Liveweight gain (LWG) was predominantly affected by grazing intensity, as LWG per sheep and per ha decreased and increased, respectively, with increasing grazing intensity. However, responses varied among years: LWG per sheep was maximized by light grazing in the drought year and by moderate grazing the wet year. Our results showed that herbage shortage at high grazing intensities reduces LWG per sheep and thus diminishes responses in LWG per ha. Nevertheless, the highest grazing intensity provides highest animal production per ha in the short term; however, this is not sustainable in the mid‐ and long term because decreasing HP induces degradation processes. Based on our results, a reduction in grazing intensity that still provides 78% of the maximum LWG per ha meets the requirements of a sustainable grazing management.

Spatio-temporal patterns of herbage availability and livestock movements: A cross-border analysis in the Chinese-Mongolian Altay

“…It may therefore be concluded that the herd mobility patterns observed in the Altay-Dzungarian region is balanced for the seasonal variability in herbage quality (Yoshihara et al 2013). With values of approximately 0.05 to 2.5 kg DM of above-ground herbaceous biomass per kilogramme live weight and day, the herbage allowance in the study region was at the lower end of values reported for pastures in Inner Mongolia (0.7 to 26.4 kg DM per kilogramme live weight; Schönbach et al 2012;Bösing et al 2014). According to Lin et al (2011) who categorized herbage allowances (kg DM kg −1 live weight), the values obtained in our study correspond to the classes 'heavy grazing' and 'very heavy grazing' during all seasons.…”

“…These circumstances may be aggravated according to climate change predictions for the Altay-Dzungarian region that foresee an increase in the average annual temperature, more frequent and prolonged summer droughts and temporal shifts of precipitation from summer to winter (Angerer et al 2008;Lkhagvadorj et al 2013a;Hilker et al 2014;Liao et al 2014a). Moreover, herd management such as daily herding practices and grazing duration, livestock numbers and herd composition are known to affect the occurrence, frequency, distribution and growth of grassland species and thus herbage yield and its nutritive value (Briske et al 2003;Schönbach et al 2012;Kreutzmann 2013a;Lkhagvadorj et al 2013b;Hilker et al 2014).…”

“…Nonetheless, the observed herbage offers were relatively low compared with studies in similar climatic contexts elsewhere (Sankey et al 2009;Behnke et al 2011;Sasaki et al 2012;Tao et al 2013), whereas the nutritive values were relatively high and constant throughout the studied years. Especially the latter observation is surprising, as in Central Asia the nutritive value of natural vegetation varies strongly with season and has been reported to be particularly low during winter and early spring (Yoshihara et al 2008;Glindemann et al 2009;Olson et al 2010;Sasaki et al 2012;Schönbach et al 2012;Bösing et al 2014;Ding et al 2014;Ma et al 2014;Müller et al 2014). It may therefore be concluded that the herd mobility patterns observed in the Altay-Dzungarian region is balanced for the seasonal variability in herbage quality (Yoshihara et al 2013).…”

“…The summer pastures at the alpine belt are characterized by a delayed snow melt which retards vegetation growth and therefore prolongs the availability of young vegetation, similar in quality to the spring pastures (Bauer et al 2011). In addition, the Umbrisols prevailing in the summer pastures in both countries are relatively rich in organic carbon and nutrients, favouring high herbage yields and high CP concentrations (Fernández-Giménez and Allen-Diaz 2001;Schönbach et al 2012), which was particularly true for the Chinese summer pasture.…”

“…Despite marked differences between China and Mongolia, both countries struggle with designing effective rangeland strategies, policies and programmes that allow to sustain rangeland productivity on the basis of fine-tuned pasture management and planning for disaster mitigation (Addison et al 2012;Sasaki et al 2012;Schönbach et al 2012;Kreutzmann 2013a;Wang et al 2013;Hilker et al 2014;Khishigbayar et al 2015).…”