Effect of continuous v. daytime grazing on feed intake and growth of sheep grazing in a semi-arid grassland steppe

Abstract

In the Inner Mongolian steppe, China, sheep generally graze during daytime and are kept in yards overnight. Hence, nutrients are not returned to the grassland, which might reduce its long-term productivity. Furthermore, the restricted grazing time may limit forage intake and thus the performance of sheep. The aim of this study was therefore to evaluate the impact of continuous 24-h grazing (CG) v. the common daytime grazing (DG) on herbage mass (HM), feed quality, feed organic matter intake (OMI) and live weight gain (LWG) of sheep in the Inner Mongolian steppe. Experiments were carried out from July to September, between 2005 and 2007 on two 2-ha plots per grazing treatment. Each month, the external faecal marker titanium dioxide (TiO 2 ) was orally administered to six sheep per plot on 10 consecutive days. Faecal grab samples were obtained from day 6 to 10 and analysed for CP concentrations to estimate digestibility of organic matter (dOM). Faecal TiO 2 concentrations were used to determine the total faecal output and hence OMI of sheep. Concomitant to faeces collection, HM and quality, as well as LWG of the animals were measured. HM and herbage quality did not differ between treatments. However, as the season progressed, concentrations of NDF, ADF and ADL increased, whereas HM and CP concentrations declined. HM and herbage quality parameters differed between years according to the annual precipitation. dOM was similar in CG (0.577) and DG (0.572) sheep, but it decreased from July (0.583) to September (0.558) and differed between years. Accordingly, the OMI of sheep was similar for both treatments across the entire grazing season and all study years. Although mean LWG differed between months and years, it was identical in CG (101.5 g/day) and DG sheep (101.8 g/day). Additional time on pasture during night does not increase feed intake or animal performance. Positive effects of a nutrient reflux on grassland productivity and herbage quality when animals remained on the plots overnight were not found, most likely because of the fact that sheep crowded together in one corner of the plots during darkness and faecal and urinary excretions were thus not evenly distributed across the entire pasture. Considering the risk of animal theft as well as the importance of sheep manure as fuel, the common penning of sheep at night seems to be an adequate management practice for pastoralists in the Inner Mongolian steppe.

Herd Size-Dependent Effects of Restricted Foraging Time Allowance on Cattle Behavior, Nutrition, and Performance

“…Therefore we propose that when forage quality is generally high across the range, cattle are able to meet their daily nutrient requirements much faster and thus increasing grazing time allowance under such conditions may be less effective in altering their food intake and performance. In addition, our findings differed from the findings of Muller et al (2011), who found no beneficial effect of 24-h grazing on food intake and performance of sheep in a Mongolian grassland system. However, it is important to note that daytime grazing duration was much longer (14-16.5 h) in the study of Muller et al (2011) than in our study (8-9 h).…”

“…In addition, our findings differed from the findings of Muller et al (2011), who found no beneficial effect of 24-h grazing on food intake and performance of sheep in a Mongolian grassland system. However, it is important to note that daytime grazing duration was much longer (14-16.5 h) in the study of Muller et al (2011) than in our study (8-9 h).…”

An increase in livestock density increases forage nutritional value but decreases net primary production and annual forage nutritional yield in the alpine grassland of the Qinghai-Tibetan Plateau

“…The FNV of the four species decreased with time, while forage maturation accelerated after June, which was also reported in previous studies (Bailey, 2004;Mekuria & Aynekulu, 2013). As species stop growing, maturation and lignification set in, with an increase in cellulose, hemicellulose and lignin and a decrease in cellular substances, such as proteins (Müller et al, 2014). These patterns are associated with a decrease in ME, IVTD and CP and an increase in NDF.…”

The Genome Landscape of Tibetan Sheep Reveals Adaptive Introgression from Argali and the History of Early Human Settlements on the Qinghai–Tibetan Plateau

“…They live and migrate closely with humans, providing a wide variety of raw sources for items such as food, clothing, fuel, transportation, and religious totems and ornaments for the indigenous population (i.e., Tibetan people) (Xian 2005; Chen et al. 2006; Peng 2010; Müller et al. 2012; Liu et al.…”