Grazing effects on the nutritive value of dominant species in steppe grasslands of northern China

Abstract

BackgroundForage nutritive value plays an important role in livestock nutrition and maintaining sustainable grassland ecosystems, and grazing management can affect the quality of forage. In this study, we investigated the effects of different grazing intensities on the nutritive values of Leymus chinensis (Trin.) Tzvelev, Artemisia spp. and Carex duriuscula C. A. Mey in the steppes of China during the growing seasons from 2011 to 2013. Five grazing management treatments were implemented: (1) rest grazing in spring, heavy grazing in summer and moderate grazing in autumn (RHM), (2) rest grazing in spring, moderate grazing in summer and heavy grazing in autumn (RMH), (3) heavy grazing though all seasons (HHH), (4) heavy grazing in spring and summer and moderate grazing in autumn (HHM) and (5) continuous moderate grazing in all seasons (MMM).ResultsThere were significant effects of year, season, treatment, and year × season and year × treatment interactions only on the crude protein of L. chinensis (P < 0.05). The crude protein concentrations of L. chinensis in the plots of constant high grazing pressure (HHH) and reduced grazing pressure in the last grazing stage (HHM) were higher than with deferred grazing (RMH and RHM, P < 0.05) in spring from 2011 to 2012. For Artemisia spp. and C. duriuscula, the crude protein concentration in HHH was higher than that in RMH (P < 0.05) in the summer of 2011. There were no significant differences (P > 0.05) for ether extract, neutral detergent fiber, acid detergent fiber and Ca concentration for any of the grasses in spring and summer from 2011 to 2013 under the different grazing management treatments.ConclusionsThe nutritive value of L. chinensis was more responsive to grazing disturbance than Artemisia spp. and C. duriuscula, and heavy grazing maintained a relatively high crude protein content in all species. Seasonal and interannual seasonal differences in grazing management combinations were two of the most important factors in determining the variability of forage nutritive value, including crude protein, ether extract, neutral detergent fiber, acid detergent fiber and calcium, for L. chinensis, Artemisia spp. and C. duriuscula. We suggest that moderate grazing should be adopted to ensure the quality and yield of forage and promote the sustainable development of animal husbandry.

Effects of mowing regimes on forage yield and crude protein of Leymus chinensis (Trin.) Tzvel in Songnen grassland

“…The CP concentration of pDMY of L. chinensis was halved from 10.79% to 4.86%, and the pDMY was doubled, which resulted in a similar pCPY and cCPY for June 1 vs. August 15 initial mowing treatments. This was consistent with previous studies that the DM yield of L. chinensis was generally negatively related to its nutritive value in various initial mowing time treatments (Donaghy et al, 2008;Zhai et al, 2018). In this study, nutritive value of rDMY of L. chinensis increased as initial mowing time was delayed from May 15 to September 1.…”

Temporal variations of herbage production and nutritive value of three grasslands at different elevation zones regarding grazing needs and welfare of ruminants

“…The abovementioned variations are considered to be among the most important constraints of livestock production (Ngwa et al, 2000) and their evaluation is essential in extensive (grazing-based) production systems. Grazing affects the quantity and quality of herbage in grasslands (Zhai et al, 2018) and subsequently the behavior and welfare of free-ranging livestock (Kilgour et al, 2012). Animals during grazing are able to select the preferred forage species and to avoid the toxic ones, express their natural behavior and maintain their health (Villalba et al, 2010;Charlton and Rutter, 2017).…”

Grazing intensity gradient inherited from traditional herding still explains Mediterranean grassland characteristics despite current land-use changes

“…Sheep tend to graze earlier (in autumn) in fenced sites (Supplementary Table 1), whereas traditional herding only begins at the end of winter/beginning of spring. Along with grazing intensity, grazing season is also recognized to be of great importance, with effects differing by season (Zhai et al, 2018). Moreover, sheep also tend to graze longer in fenced sites, as the farmers indicated during our interviews.…”