苜蓿放牧地生产性能与管理

苜蓿(Medicago sariva)放牧草地以其成本相对低、营养价值高、家畜生产性能优异而得到生产者的青睐.但用于干草的苜蓿不耐践踏,不适合放牧,而且家畜鼓胀病也限制其利用,因而使之成为苜蓿科研的新方向.有关放牧型苜蓿品种的选育以及家畜鼓胀病的管理研究,笔者将分别在其他文章中阐述.本文主要就苜蓿放牧地的管理(放牧方式、时间和强度)、合理利用及其对不同家畜生产性能的影响,以及目前育成的放牧型苜蓿品种进行综述,以期为苜蓿放牧的管理和利用提供参考.     

Use of Best Management Practices and Pasture and Soil Quality on Maryland Horse Farms

Agricultural operations, including horse farms, can contribute nonpoint source (NPS) pollution to surface water. The use of best management practices (BMPs) is the most effective way to prevent the movement of pollutants to surface water from nonpoint source pollution. Previous mailed survey studies have assessed the use of BMPs at the county and state level, but a visual assessment of horse farms is necessary to validate survey results. An observational field study was conducted to assess BMP use and soil and pasture quality and to create a model to predict soil erosion on Maryland horse farms. Fifty-one farms were selected based on stocking density (acres per horse [ac horse^-1]), farm use, and presence of water on property. All farms were visited from September through November 2009. In each pasture with grazing horses, the correct use of BMPs was assessed, grass height and vegetative cover were measured, and composite soil samples were collected. Less than half of the 18 assessed BMPs were being used by participants. Although most participants maintained the recommended vegetative cover and grass height, soil erosion was a major problem in pastures. Most farms had optimum soil nutrient concentrations (Ca, K, and P), excessive Mg values, and basic soil pH. Vegetative cover and grass height measurements were positively correlated with stocking density (r = 0.345, P < .0001; and r = 0.291, P < .0001, respectively). Farm use was the only variable that predicted soil erosion on farms (P = .006). Farms used for pleasure were least likely to have soil erosion, whereas farms used for breeding were more likely to have soil erosion (P = .0058). Despite the low-to-moderate adoption of BMPs, the maintenance of recommended vegetative cover and grass height as well as optimum values of soil nutrients indicated participating Maryland horse farms have a low potential for nutrient movement and NPS pollution.     

Long-Term Maize,Sorghum, and Millet Monoculture Effects on an Argentina Typic Ustipsamment

Maize, sorghum, and millet monoculture effects on soil properties of a Typic Ustip samment in the semiarid pampa of Argentina were evaluated after 27 years in a plot experiment. A permanent Eragrostis curvula pasture was used as a reference. Millet was the most destructive crop to the soil because it decreased dry aggregate stability by 10%, soil organic matter (OM) by 30%, extractable K by 20%, available P by 44%, inorganic P by 11%, available Fe by 20%, available Zn more than 90%, available Cu by 30%, and available Mn by 26%, and it increased wet aggregate instability by 75%. Grain sorghum was less destructive to the soil than millet because it only decreased OM by 30% and extractable K by 24%. All studied crops decreased the cation exchange capacity of the soil between 20 and 30%, the pH values, and the concentration of soil extractable Mg2+by 38 to 63%. Soil extractable Ca2+ was decreased 30% by the Eragrostis pasture and 40% by maize. The negative effect of millet and grain sorghum on OM was attributed to a low coverage of the soil with plant residues left by these crops as well as the long exposition of the bare soil during temperate and wet periods. Decreases of soil nutrient contents were attributed to plant uptake in all cases, except the Zn concentrations, which were related to variations on soil pH and phosphate concentrations. It was concluded that maize, the most commonly cultivated crop in the region studied, did not affect physical and chemical soil properties to a large extent. Conversely, millet had the most negative effect on physical and chemical properties of the soil.     

Ingestion of energy, protein and amino acids from pasture by grazing European wild boar (Sus scrofa L.) in a semi-extensive production system

The aim of the study was to determine the apparent consumption of dry matter (DM), gross energy (GE), crude protein (CP) and amino acids (AA) from pasture by European wild boar in a pastoral system. Two pasture-types were used, one consisting predominantly of Lolium perenne L. and the other predominantly of Plantago lanceolata L. The study was conducted in Spring and repeated in Summer. Twelve purebred European Wild Boar of 18.8 ± 0.8 kg (mean ± sem) with nose rings were randomly grouped into six pairs. Each day of the 19-day study, a pair of animals was placed into each of three areas of a pasture strip (1.4 × 6.3 m per area) from each pasture type from 8:30 h until 16:30 h, after which the animals entered a barn and had free access to a commercial diet for 45 min, with each pasture strip being grazed once. Pasture samples were taken on days 4 to 19 from each grazed area pre- and post-grazing and the DM content of these samples was used to calculate DM consumption of the animals. Additional pasture samples were collected and analysed for gross energy, crude protein and amino acids. The wild boar consumed (mean + SEM) 418 ± 72.2 and 210 ± 38.3 g of DM per day in the L. perenne paddock during Spring and Summer, respectively, and 550 ± 85.9 and 226 ± 44.8 g DM per day in the P. lanceolata paddock during Spring and Summer, respectively. The amount of DM, energy, crude protein and amino acids that the animals consumed varied markedly between days, but did not significantly differ in amount between the L. perenne and P. laceolata paddocks. However, the consumptions were significantly lower in Summer than in Spring. It is estimated that the wild boar would have satisfied somewhat less than 90 and 45% of their daily maintenance digestible energy requirements through consumption of pasture when grazing the L. perenne paddock in Spring and Summer, respectively.     

Evaluation of Eucalyptus Camaldulensis (river GUM) and Chamaecytisus Proliferu (Tagasaste) for salinity control by agroforestry

Components of the soil water balance were measured over a three year period for Eucalyptus camaldulenis and Chamaecytisus proliferus, species commonly used for revegetation in Western Australia, and compared with water balance components for pasture. Marked seasonal trends in evapotranspiration were observed for all species with maxima occurring in the wet months, and minima occurring in summer when rainfall was low and evaporative demand high. in each year of study, annual evapotranspiration and soil water depletions were greater for both tree species than for the pasture, due to the greater extraction of soil water at depth. Upward movement of water from the saturated zone was also found to be greater beneath the deeper rooted perennials than beneath pasture.     

Impact of protection and free grazing on sand dune vegetation in the Rajasthan Desert,India

In the Thar (Rajasthan) Desert of India, sand dunes and sandy plains dominate the landscape. Livestock raising and marginal land cultivation are the main occupations. Owing to the high growth rates of human and livestock populations and a decrease in pasture area and its primary productivity, these lands bear acute grazing pressure. Average rainfall is low and vegetation growth is restricted to the short rainy season of two to four months duration. Often there are years of lower than normal rainfall. In these circumstances, fenced areas, established to stabilize formerly active sand dunes, are increasingly opened to grazing to prevent high stock mortality during droughts. This study was conducted in four fenced and one open site, representative of the region's different vegetation types and grazing pressures. The impact of 2 and 5 per cent free grazing pressure on protected sand dune vegetation density and cover was tested in the two fenced sites. The vegetation data for grazed sites are compared with those for the two ungrazed fenced (protected) and one unfenced (open) site subjected to unlimited grazing pressure throughout the year. The vegetation sampling was carried out by the qaudrat and line-transect method before and after grazing from November 1984 to October 1986. It shows a significant reduction in the density and cover of many palatable species and an increase of unpalatable plants. The effect of vegetation degradation is greater in the unfenced area. The low grazing pressure on the fenced sand dunes sites can still cause drastic changes in the vegetation density and cover. Protection resulted in reduced sand erosion and enhanced growth of palatable plants in the fenced sites under similar climatic and edaphic conditions to the unfenced sites. The grazing pressure in the unfenced areas remains high to extreme during the year, due to low land productivity and high feed demand. The regeneration rate is very slow under the constant (3rd to 5th degree) overgrazing. Low intensity grazing pressure on the fenced sites during droughts can cause heavy utilization and mortality of palatable vegetation.