王牌鹅种——昌图豁鹅

昌图豁鹅起源于辽宁省昌图县。此鹅种是当地人们经过多年的群选群育以及县、乡、村三级选育场和扩繁场提纯复壮培育而成 ,该鹅具有生长快 ,适应性强 ,宜放牧 ,体型小 ,繁殖力强 ,产蛋量高 ,抗病力强 ,耐粗饲 ,饲料报酬高 ,羽毛洁白 ,肉质鲜嫩 ,商品价值高等优点 ,现已在国内外享有很高的声誉。昌图豁鹅以草食为主 ,饲养简单 ,不需特殊设备。饲养昌图豁鹅确实是一项投资小、产出高、见效快的致富项目。具体介绍如下。1　外貌特征　昌图豁鹅体型小 ,呈长方型 ,体质健壮 ,结构匀称、紧凑细密。羽毛全白色 ,头较小 ,眼呈三角形。在上眼睑边缘上…     

Sediment Load in Runoff Under Laboratory and Field Simulated Rainfall

Soil erosion is one of the most important problems in the Loess Plateau of China affecting sustainable agriculture. Near Luoyang (Henan Province, China), field plots were constructed to measure soil erosion rates under conventional tillage practices using field-simulated rainfall.Field rainfall experiments were carried out to compare previous results from laboratory rainfall simulations on the same soil for interrill conditions. Although in the laboratory experiments, a strong correlation was found betweenthe stream power of the runoff water and the unit sediment load, this sediment transport equation overestimated the field rainfall simulation results. Another sediment transport equation derived by Nearing et al. for rill erosion was in better agreement with the results of the field experiments, although it also overestimated these values. The measured sediment load values during the field rainfall simulations were also lower than those found during field experiments on the same soil but with a loosened surface layer. This difference indicates the importance of soil physical condition of surfce like soil structure and aggregate size, which may contribute to the discrepancy between the field and laboratory experiment results.     

提高奶牛繁殖率的主要途径

目前，奶牛作为畜牧业的一个新兴产业正处于迅速发展阶段，然而，奶牛养殖户所饲养的部分奶牛繁殖率偏低，主要表现为母牛产犊后发情推迟、情期受胎率低等，严重制约了奶牛业的快速发展。因此，奶牛饲养者必须高度重视影响母牛繁殖率的各种因素，并采取有效措施，充分提高奶牛的繁殖性能，以便获得最大的经济效益。