中华民国时期西北地区牧草资源研究刍考

中华民国西北地区的牧草资源研究代表了当时中国牧草科技领域的最高水平，但目前相关考证研究较少。为此，采用文献考证和历史分析法，以现存的近代报刊为主要资料来源，开展文献整理、甄别和考察分析，并结合现代牧草科技成果总结归纳。结果表明,学界及少数政府人士开展的西北地区牧草资源的调查研究大致以20世纪30年代初为始，其中植物学学者调查区域集中在陕西省，主要方法为牧草的植物学分类和植物特性研究，水土保持学学者的调查区域包括陕甘青等沿黄省份，目的为搜集到利于水土保持的优质草种，畜牧学学者的调查关注点则是牧草的分布、品种、品质、贮藏等方面。牧草引进是西北地区的另一项主要工作和成就，以王栋和叶培忠等为代表的学者们运用西方试验科学的理论方法持续开展了牧草试种或栽培试验。同时，西北地区还在牧草资源的育种、保藏、营养及配合饲喂等试验研究上有所开拓，其中很多研究为当时国内唯一。此外，西北地区的牧草科技推广也有所发展，但总体上以资源调查和栽培、育种、保藏等实验为主。     

几种禾本科牧草开花结实特性的研究

本文研究了波碱草等6种中国北方常见禾本科牧草的开花结实特性，描述了植物的开花形态，花器变化等特征，讨论了小花开花顺序，开花持续期以及结实率等特性对种子生产的影响和作用。     

Some challenges and opportunities for grazing dairy cows on temperate pastures

Grazing plays an important role in milk production in most regions of the world. In this review, some challenges to the grazing cow are discussed together with opportunities for future improvement. We focus on daily feed intake, efficiency of pasture utilization, output of milk per head, environmental impact of grazing and the nutritional quality to humans of milk produced from dairy cows in contrasting production systems. Challenges are discussed in the context of a trend towards increased size of individual herds and include limited and variable levels of daily herbage consumption, lower levels of milk output per cow, excessive excretion of nitrogenous compounds and requirements for minimal periods of grazing regardless of production system. A major challenge is to engage more farmers in making appropriate adjustments to their grazing management. In relation to product quality, the main challenge is to demonstrate enhanced nutritional/processing benefits of milk from grazed cows. Opportunities include more accurate diet formulations, supplementation of grazed pasture to match macro- and micronutrient supply with animal requirement and plant breeding. The application of robotics and artificial intelligence to pasture management will assist in matching daily supply to animal requirement. Wider consumer recognition of the perceived enhanced nutritional value of milk from grazed cows, together with greater appreciation of the animal health, welfare and behavioural benefits of grazing should contribute to the future sustainability of demand for milk from dairy cows on pasture.     

Responses of herbage P,Ca, K and Mg content and Ca/P and K/(Ca + Mg) ratios to long‐term continuous and discontinued cattle grazing on a rough fescue grassland

Herbage minerals affect performance of grazing cattle. We investigated the response of herbage P, K, Ca and Mg contents and Ca/P and K/(Ca + Mg) ratios to long‐term stocking rate, continuous vs. discontinued grazing practice, and sampling year. Cattle had been stocked at 2·4 and 4·8 animal unit months ha^?1 since 1949. Exclosures were installed in April 1998. Herbage samples were collected near peak herbage mass in 2001, 2003, 2008 and 2012 and analysed for mineral content. Mineral contents were similar between the two stocking rates, but were lower (P < 0·05) under discontinued than continuous stocking, with the exception of similar P contents. The content of P and K in herbage was higher and the content of Ca and Mg was lower (P < 0·05) in years with greater precipitation and lower temperatures. Herbage mineral content, with the exception of P, exceeded minimum recommended levels for cattle. Given the low P content in herbage (0·74–1·19 g kg^?1) and high Ca/P ratios during the dry and hot year (of 2001), a dietary P supplement should be considered for cattle grazing rough fescue grassland in drought years. The low K/(Ca + Mg) ratios (<2·2) suggest there is little risk of grass tetany in cattle grazing on this grassland.     

Antimony and Arsenic Uptake by Plants in an Abandoned Mining Area

Abstract

The degree of antimony (Sb) and arsenic (As) pollution and their bioavailability in mining‐affected grassland soils were determined. Antimony and As concentrations in aboveground parts of plants, collected in three consecutive years, were measured to investigate their uptake capacity, food chain contamination, and ecological risks. Total Sb and As contents in soils ranged from 60 to 230 mg/kg and from 42 to 4530 mg/kg, respectively, indicating a high degree of pollution of soils. The mobile fractions of Sb (0.02–0.27% of the total Sb content) and As (0.02–0.70% of the total As content) in soils, which reflect the plant‐available portion, are extremely low compared to total Sb and As contents in soils. The Sb and As contents in plants were also very low in both study areas. This lower accumulation of Sb and As in the plants is attributed to the low bioavailability of Sb and As in mine soils. Antimony and As contents in some plants were lower than the controls, and the concentrations in some plants were slightly higher than the normal grass mean level but were less than the phytotoxic or toxic levels for human or livestock consumption. The results of this study demonstrate that the plants growing in these mining areas, which have evolved As and Sb tolerance and detoxification capacity, can be cultivated to phytostabilize the metalloid‐contaminated mining sites.     

枣园间种牧草对树上天敌功能团的影响及其作用评价

对枣园间种牧草对树上天敌功能团的影响及其作用评价进行系统研究.结果表明:两类枣园树上天敌功能团的多样性与优势度系数有明显(P＜0.05)差异,枣园种草对树上天敌功能团的演替产生一定的作用,枣树不同发育阶段中,天敌功能团的群落参数随物候而改变;枣园种草对于受化学农药干扰的天敌功能团种群的恢复与重建有促进作用;根据Sn/Sp、Ei/Pi和ds/dm3种指数的大小,评价了枣园天敌功能团对害虫的控制作用,发现种草园的天敌功能团对枣树害虫的控制能力要比未种草枣园强;相关性测定表明:天敌群落学的研究中可以用功能团替代物种.     

Clearcutting Brazilian caatinga: assessment of a traditional forest grazing management practice

Clearcutting is a common practice for removing woody vegetation in the semiarid tropics of northeast Brazil. The prevalent belief is that clearing increases carrying capacity for livestock by increasing herbaceous vegetation, yet little empirical evidence exists to support or refute the contention. We investigated the implications to small ruminant nutrition of clearcutting in the semiarid tropics of northeast Brazil. We found that biomass of herbaceous species increased sixfold following cutting of trees, but much of this increase was in the form of poorly palatable stem. The large supply of leaf litter from woody species that was typical of uncleared areas during the dry season was replaced by persistent green foliage on coppicing trees the year following clearing. This green foliage may enhance the nutritional quality of the diets of sheep and goats foraging on cleared areas during the dry season.     

Pasture floristic composition in different Eucalyptus species plantations in some parts of northern Guinea savanna zone of Nigeria

In view of the recurrent drought and human population pressures which have drastically reduced the density of pasture species within the Nigerian savannas, the nomadic herdsmen rely mostly on silvipastoralism, grazing their herds in Eucalyptus plantations. In this study, the population of understorey forage and non-forage speicies and the relative light intensities on the forest floors of two Eucalyptus species, viz: E. citridodora, and E. camaldlensis were compared with those of open savanna lands at Kabama, Samaru and Guga, all within the Northern Guinea savanna zone.At normal 3 m by 3 m spacing between trees, the herbages were fewer in the plantations and the E. citridora plantation had only about half the number of species observed under E. camaldlensis in the same and other sites despite similarities in light intensity levels in all the plantations. This information forms a guideline in using eucalyptus silvo-pastoral farms.     

Fodder grass productivity and soil fertility changes under four grass+tree associations in Kerala, India

Adapted tree+grass combinations make a valuable contribution to forage production in the Indian peninsula, but knowledge of the interactive effects between trees and grasses on their production is limited. We, therefore, conducted a field experiment involving combinations of four trees and grasses, besides monospecific grass controls, for seven years, to investigate grass productivity in association with leguminous and non-leguminous multipurpose trees (MPT) having disparate canopy architecture, and to assess the end-of-rotation soil fertility changes. Post rotation changes in herbage productivity were evaluated by growing teosinte (Zea mexicana) for three years. The four MPTs were Acacia auriculiformis, Ailanthus triphysa, Casuarina equisetifolia and Leucaena leucocephala. Grasses included Pennisetum purpureum (hybrid napier), Brachiaria ruziziensis (congo signal), Panicum maximum (guinea grass) and teosinte. Lower tree branches were pruned from fifth year. Understorey herbage production increased until three years in all tree+grass combinations, but declined subsequently, as tree crowns expanded. Overall, casuarina among MPTs, and hybrid napier and guinea grass among forage crops, were more productive than others. Pruning MPTs generally favoured greater herbage production. Understorey light levels for acacia, ailanthus, casuarina and leucaena were 17, 60, 55 and 55% of that in the open at five years. During the post-rotation phase, MPT plots were characterised by higher soil nutrient capital and consequently teosinte yields were higher than in the treeless control treatment. All previous tree-grass combinations showed an increasing trend till two years after MPT felling. Yield levels declined subsequently, despite at variable rates. Careful selection of the tree and grass components is, therefore, crucial for optimising herbage productivity in silvopastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of herbage intake on goat performance in the mediterranean type natural pastures

This study aimed at identifying changes in natural pastures during the grazing season and investigating the effects of these changes on pasture feeding potential for high yielding dairy goats. During the study, 12 dairy goats were grazed on a 1.5 ha natural pasture for three months from April to June in 2003, 2004 and 2005. The goats were fed 0.5 kg/day of concentrate as a supplement during the grazing season. Botanical composition, herbage production and intake, crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents of the pasture were determined. Live weight, milk yield, milk dry matter (DM) and fat content of the goats were monitored. The data were analyzed using a linear model, which evaluated the effects of grazing seasons in each year. Based on the three-year average, 87% of pasture was herbaceous plants and the remaining was shrubs in DM basis with Cistus creticus , Quercus ithaburensis , Pistacia atlantica and Asparagus acutifolius being the major shrub species. The herbage yield in June was significantly lower than in other months in all years ( P  = 0.001). In all experimental years, the CP content of the pasture decreased but the structural carbohydrates increased as the grazing season proceeded. While live weight was not affected by grazing periods except for 2004 ( P  = 0.001), milk yield significantly decreased with advancing grazing period ( P  = 0.001). The results of the present study indicate that natural pasture has a supportive effect in April and May on the milk yield of lactating goats which are in mid-lactation, and suggested that supplementary feeding is required in consecutive grazing periods.