A Simulative Study on Effects of Climate Warming on Nutrient Contents and In Vitro Digestibility of Herbage Grown in Qinghai-Xizang Plateau

The increasing trend of air temperature along with the climate warming has been accepted gradually by scientists and by the general public. Qinghai_Xizang Plateau, a unique geographic unit due to high_altitude climate, is one of the most susceptible regions to climate warming. Its ecosystem is very fragile and sensitive to climate change. In order to get a better understanding of the impacts of climate warming on the nutrient contents of herbage grown in Qinghai_Xizang Plateau, a simulative study was implemented at Daban Moutain by using temperature differences resulted from sites selected at different altitudes and nutrient contents and in vitro digestibility were determined for assessing the quality of the grown herbage. There were significant downtrends in crude protein (CP), ether extract (EE) and nitrogen free extract (NFE) contents of herbage along with the increase of temperature. It had a positive correlation between temperature and content of acid detergent fibre (ADF), acid detergent lignin (ADL) in herbage. In vitro digestibility of herbage decreased along with the increase of temperature. The results of this study indicated that climate warming significantly influence nutrient contents and in vitro digestibility of herbage grown in Qinghai_Xizang Plateau. It is suggested that the future climate warming especially the gradual rise of the night temperature could cause negative effect on herbage quality grown in Qinghai_Xizang Plateau by decreasing CP, EE, and NFE contents and increasing some indigestible ingredients such as crude fibre (CF), neutral detergent fibre (NDF), ADF, and ADL. This, consequently, decreases the ruminant assimilation ability.

Perspectives and Challenges of Italian Catalogue of Herbage Varieties

In Mediterranean countries forage crops and temporary grasslands are the most important supply even if severe moisture stress is common. In Italy, forage systems are various and differently located from North to South of the mainland due to strong influence by rainfall distribution. Grasses and grazing cover 3.4 million ha of Italian utilized agricultural area （UAA） while alternated grassland and grass meadows cover 1.9 million ha. Most of grasslands are located in hilly and mountainous areas and are important for reducing erosion. Italy has a great longitudinal extension which accounts for a great variety of climate systems and soils： the northern regions have a humid subtropical climate and differ greatly from the south part that fits the Mediterranean climate profile. During the last 100/150 years the Italian climate has become warmer and drier showing an increase of erratic precipitation intensity. The future of breeding of forage grasses and legumes should be focused on higher nutrient use efficiencies and increased sustainability. New applications of genomics and bioinformatics will allow advanced breeding strategies. Over the past 15 years breeders have displayed a constant interest in forage species while a greater interest has risen in turfgrass varieties. Seed production of Italian herbages does not cover the requirements of the market. More specific value for cultivation and use （VCU） tests might be an effective means to improve the screening of candidate varieties. The goal is the selection of varieties able to withstand the stress of climate change, have better water and nitrogen use efficiency and resilience of vegetation cover.

Effects of rainwater harvesting on herbage diversity and productivity in degraded Aravalli hills in western India

Over-exploitation and rural growth have severely damaged native vegetations of Aravalli hills in Rajasthan, India. This study was conducted to evaluate the effects of different restoration practices （i.e., rainwater harvesting （RWH） and planting of tree seedlings） on improve- ment in soil water and nutrients and growth and biomass of herbaceous vegetation. Contour trench （CT）, Gradonie （G）, Box trench （BT）, V-ditch （VD） and a control were imposed on 75 plots （each of 700 m 2 ） in natural slope gradient defined as 10%, 10% 20% and 20% slopes in 2005. Each plot had three micro-sites of 1-m 2 at up （USP）, middle （MSP） and lower （LSP） part of the plot for observation in 2008. The existed gradient （due to soil texture and topographic features） of soil pH, EC, SOC, NH 4 - N, NO 3 -N and PO 4 -P in June 2005 between 20% to 10% slopes were decreased in 2008 after applying RWH techniques. Such improvement in soil status promoted vegetation growth and biomass in higher slope gra- dients. Soil water, species diversity and herbage biomass increased from USP to LSP, and RWH techniques had positive role in improving SOC, nutrients, vegetation population, evenness and growth at MSP. Despite of lowest SWC, regular rain and greater soil water usage enhanced green and dry herbage biomasses in 10% 20% and 20% slopes, compared with 10% slope. The highest diversity in CT treatment was related to herbage biomass, which was enhanced further by highest concentrations of SOC and PO 4 -P. Further, CT treatment was found to be the best treat- ment in minimizing biomass variance in different slopes. Conclusively, soil texture and topographic features controlled soil water and nutrients availability. Rainwater harvesting techniques increased soil water storage and nutrient retention and also enhanced vegetation status and biomass by minimizing the effects of hillslopes. Thus depending upon the site conditions, suitable RWH technique could be adopted to increase herb- age biomass while rehabilitating the degraded hills.

Intake, Energy Expenditure and Methane Emissions of Grazing Dairy Cows at Two Pre-Grazing Herbage Masses

A grazing experiment was undertaken to assess the effects of two levels of herbage mass (HM) on herbage DM intake (DMI), fat and protein corrected milk yield (FPCM), grazing behaviour, energy expenditure (HP), and methane emissions (CH4) of grazing dairy cows in spring. Treatments were a low HM (1447 kg DM/ha;LHM) or a high HM (1859 kg DM/ha;HHM). Pasture was composed mainly of cocksfoot (Dactylis glomerata) and lucerne (Medicago sativa), offered at a daily herbage allowance of 30 kg DM/cow, above 5 cm. Eight multiparous Holstein cows were used in a 2 × 2 Latin Square design in two 10-day periods. Despite the differences in pre-grazing HM between treatments, OM digestibility was not different (P = 0.28). Herbage mass did not affect DMI or FPCM. Grazing time was not different between treatments, but cows had a greater bite rate when grazing on LHM swards. However, HP did not differ between treatments. Daily methane emission (per cow), methane emission intensity (per kg FPCM) and methane yield (as percentage of gross energy intake) were not different. The lack of effect of the amount of pre-grazing HM on energy intake, confirms that the difference between HM treatments was beyond the limits that impose extra energy expenditure during grazing.

Effect of Weed Control on Establishment and Herbage Production in Dwarf Napiergrass

Weed control is a crucial factor for maintaining establishment and herbage production in dwarf variety of late-heading type （DL） napiergrass （Pennisetum purpureum Schumach） in southern Kyushu, Japan. This study was aimed to verify the weeding-effect on dry matter （DM） production in the farm level and to examine the effect of several weed control, i.e. mixed sowing of annual setaria （abbreviated as S）, which has no regrowth ability after stem-elongation, paper-mulching （as P） and hand-weeding （as ＋W）, compared with no-weeding （as -W） on DM yield and quality of DL napiergrass in two years. Weed control practices significantly （P 〈 0.05） promoted several plant growth attributes in DL napiergrass, compared with no-weeding both in the farm and experimental levels. Paper-mulchidng （P-W or P＋S-W） had highest yields among several practices in both years. Setaria-sowing ha a partially mitigating effect of weed damage on DM production of DL napiergrass, while additive DM gain from setaria could compensate the yield decrease in DL napiergrass and reduce herbicide cost. Neither digestibility nor crude protein was affected by any weed control in either year. Thus, paper-mulching and annual setaria-sowing could be effective alternative practices for weed control of this species.

Estimation of herbage intake and digestibility of grazing sheep in Zhenglan Banner of Inner Mongolia by using n-alkanes

To reveal the seasonal dynamics of herbage intake, diet composition and digestibility and clarify the relationship of those with herbage nutrient and botanical composition of grazing sheep in Zhenglan Banner of Inner Mongolia, the n-alkane technique was used to test in sheep grazed during June, August and December. The results showed that the sheep mainly ate Fringed sagebrush, Stipa krylovii and Carex in proportions of 33.5,17.9 and 21.2%, respectively, in spring. In summer, the sheep consumed cleistogenes,Potentilla tanacetifolia, Thyme, etc; the intake of Fringed sagebrush, Carex and Stipa declined. In winter,Fringed sagebrush accounted for 50.1% of herbage intake, and the intakes of Cleistogenes and Stipa krylovii increased to 15.3 and 18.4%, respectively. Herbage intake by the sheep in spring was 1.8 kg DM/d, and digestibility was 71.4%. Herbage intake and digestibility decreased slightly to 1.7 kg DM/d and 68.4%during the summer, respectively and decreased significantly to 1.2 kg DM/d and 36.4% in winter. There were significant correlations between diet composition and CP content in winter, diet composition and botanical composition in summer. A highly positive correlation between herbage intake and digestibility was observed in grazing sheep.

Effects of Vegetation Cover, Grazing and Season on Herbage Species Composition and Biomass: A Case Study of Yabello Rangeland, Southern Ethiopia

The Yabello rangeland is a semi-arid area in Borana, Ethiopia that is facing great degradation challenges. Increasing infestation of vegetation cover, over grazing and high seasonal variation have significantly affected the herbage composition and biomass in the Yabello rangeland. This study focused on assessing the effect of vegetation cover, grazing and season on both herbage composition and biomass in the Yabello rangeland. An experiment was conducted using randomized plots of 1m×1m. Sites were selected based on vegetation cover type and grazing variation, and seasonal impacts were also assessed. Data on herbage composition, height and mass with respect to those parameters were analyzed using SAS statistical software version 9.1(SAS Institute, 2001) and Microsoft Excel. A total of 26 grass species were recorded and Chloris roxburghiana Chrysopogon aucheri and Chrysopogon aucheri grass species showed the highest average single species cover height and biomass production, for all the sites among all parameters. As a result, those grass species are highly recommended for the rehabilitation of degraded rangeland in the study area. This study also showed that vegetation cover type grazing and seasonal variation were the key factors in determining herbage species composition, height and biomass production. Finally, we recommended that sustainable management which controls bush vegetation cover and balances grazing levels is essential for sustainable herbage production and biodiversity conservation in the area.

Research Progress of Grassland Feed-animal Balance at Home and Abroad

Feed-animal balance is the key technique on the grassland ecosystem management,and attracts widespread attention in the world.Many studies have been conducted by former researchers,and most of their efforts were intended to keep the balance of feed-animal.However,there are still much more issue needed to be studied in details on the face of grassland degeneration and animal husbandry sustainable development.The author analyzed the feed-animal balance research progress,including the concept of stocking rate and its practical management techniques,especially on the stocking rate calculation methods.In addition,the social and economy effects on feed-animal balance were also discussed during the progress of improving the development of pastoral economy.In order to achieve feed-animal balance more effectively,it was concluded that the focus must be shift from only on animal number to the grassland quality,and it's necessary to strengthen market tax control.

Sward Structural Characteristics and Performance of Beef Heifers Reared under Rotational Grazing Management on Campos Grassland

This study aimed to evaluate the effect of two rest intervals on structural sward characteristics and productive performance of beef heifers reared on Campos grassland managed on rotational grazing. The treatments were two intervals between grazing of 375 and 750 DD (degree days), based on thermal cumulative sum for leaf expansion of native grasses belonging to two functional groups. The experimental design was a randomized complete block design with two treatments and three replications. The tested animals were beef heifers with initial age of 12 months and average weight of 185.2 ± 17.4 kg. Measures in the pasture were: herbage mass, mass of green leaf blades, stem mass, dead material mass and green leaf allowance. The 750 DD rest interval presented higher herbage mass (24%), higher green herbage mass and 19% more leaves in the canopy. This rest interval also presents a high proportion of dead material and stems in the sward structure. In the other way, the 375 DD rest interval presents better chemical characteristics, with 20% more crude protein in the hand plucking samples. Heifers’ dry matter intake was similar between the rest intervals (2.04% of live weight) and the bite mass was also similar (0.22 g DM per bite) but the animal performance was higher in the 375 DD rest interval. The stocking density showed similarity between treatments with an average of 875 kg/LW/ha. The live weight gain per area was higher in 40 kg/LW/ha (P = 0.117) for 375 DD rest interval, reaching 251 kg/LW/ha produced over the 149 experimental days. Based on these results, we can conclude that the treatment of shortest interval between defoliation gave the highest gain individual animals in warm seasons.

Productivity and Grazing Behavior of Ewes with Single or Twin Lambs Raised in Mixed Italian Ryegrass/White Clover Pasture in Southern Brazil

The aim of this study was to compare the area production and grazing behavior of single- and twin-rearing ewes kept on a mixed Italian ryegrass/white clover pasture. The herbage allowance was maintained at 12 kg DM/100kg live weight during the experiment, by continuous variable stocking management for 112 days (4 periods of 28 days). We measure the live weight gains, the area production and the body condition score of ewes and lambs. Animal behavior was observed on four occasions during which we evaluated whether the lambs were grazing near to or far from their mother. Live-weight output from the ewes and lambs, and net output (ewes and lambs) were calculated. Results showed that being irrespective of birth type, ewes had similar mean daily weight gains, although ewes with twin lambs presented a mean lower body condition score. Ewes live weight output/ha did not differ significantly among birth types, but twin lambs produced 98.2 kg (45%) more live weight gain/ha. Total net live-weight output (ewes + lambs) was 121.5 kg greater for twins than for singles. Ewes with twin lambs spent more time grazing and ruminating. Lambs increased the time they spent grazing in each successive period. Single lambs spent significantly longer time grazing within 12 m of their dams (near grazing). Analysis of far grazing times by the broken line method showed that growing lambs rapidly increase the time spent far grazing up to a live weight of 20.3 kg in both birth types, which occurs at 95.3 and 115.9 days of age for single and twins, respectively. The results indicate that twin lambs are more productive than singles, when evaluated per area unit of pasture.