Indoor Versus Outdoor Calf Rearing at Three Weaning Ages

In order to be profitable, a dairy herb must have good heifers to meet replacement needs. According to USDA (51), these needs are substantial because 25% of the cows in an average herd must be replaced each year as they no longer return a profit. Meeting these herd replacement needs has long been a serious problem of the dairyman. Nation-wide calf loss estimates ranged between 8 and 25% with an estimated annual loss to the industry of $50 million (10). South Dakota dairymen are not immune to these mortality losses and some studies (28, 52) indicate that their losses may be higher than the national averages. The fluctuating climate of the upper Midwest is such that an adequate housing system design to meet calf needs is hard to define. Previous preliminary studies at South Dakota State University showed some advantage of rearing calves in individual portable outside pens rather than in the conventional enclosed calf barn used by most dairymen in the state. This study was initiated to determine some of the advantage an outdoor rearing system held over the conventional indoor rearing system, and to determine the most economical and most efficient age to wean a calf from whole milk, whether it be in an indoor or outdoor system

Will the U.S. productivity resurgence continue?

U.S. productivity growth has accelerated in recent years, despite a series of negative economic shocks. An analysis of the sources of this growth over the 1995-2003 period suggests that the production and use of information technology account for a large share of the gains. The authors project that during the next decade, private sector productivity growth will continue at a rate of 2.6 percent per year, a significant increase from their 2002 projection of 2.2 percent growth.Productivity ; Information technology

Projecting productivity growth: lessons from the U.S. growth resurgence

Following the 1995-2000 period of more rapid output growth and lower inflation in the United States, economists have strenuously debated whether improvements in economic performance can be sustained. The recession that began in March 2001 intensified the debate, and the economic impacts of the events of September 11 have yet to be fully understood. Both factors add to the considerable uncertainties about future growth that currently face decision makers in both the public and private sectors. ; In this article, the authors analyze the sources of U.S. labor productivity growth in the post-1995 period and present projections for both output and labor productivity growth for the next decade. Despite the 2001 downward revisions to U.S. gross domestic product and software investment, the authors show that information technology (IT) played a substantial role in the U.S. productivity revival. The article then outlines a methodology for projecting trend output and productivity growth. The base-case projection puts the rate of trend productivity growth at 2.21 percent per year over the next decade with a range of 1.33 to 2.92 percent, reflecting fundamental uncertainties about the rate of technological progress in IT-production and investment patterns. The central projection is only slightly below the average growth rate of 2.36 percent during the 1995-2000 period.Productivity ; Technology ; Economic development

Density Distribution of Fish in the Presence of Whales at the Admiralty Inlet Landfast Ice Edge

Hydroacoustic techniques were used to search for fish beneath landfast sea ice in Admiralty Inlet, Northwest Territories, Canada, when narwhal (Monodon monoceros) and beluga whales (Delphinapterus leucas) were congregating at the ice edge in the mouth of the inlet. Fish, presumably Arctic cod (Boreogadus saida), were distributed in the water column within four general layers or zones; near the ice undersurface, about 40 m deep, about 80-100 m deep, and about 150-200 m deep. The distribution of the first three layers roughly corresponded with the distribution of larger zooplankters, also estimated hydroacoustically. We recorded higher densities immediately below the ice than farther down in the water column. Maximum density in both regions occurred about 10 km from the ice edge. Fish density was low in the immediate vicinity of the ice edge. The distribution of fish underneath the landfast ice of Admiralty Inlet is postulated to have been influenced by the distribution of zooplankton, their principle food source, rather than by the presence of whales.

Classification of the Alaskan Beaufort Sea Coast and estimation of carbon and sediment inputs from coastal erosion

A regional classification of shoreline segments along the Alaskan Beaufort Sea Coast was developed as the basis for quantifying coastal morphology, lithology, and carbon and mineral sediment fluxes. We delineated 48 mainland segments totaling 1,957 km, as well as 1,334 km of spits and islands. Mainland coasts were grouped into five broad classes: exposed bluffs (313 km), bays and inlets (235 km), lagoons with barrier islands (546 km), tapped basins (171 km) and deltas (691 km). Sediments are mostly silts and sands, with occasional gravel, and bank heights generally are low (2–4 m), especially for deltas (<1 m). Mean annual erosion rates (MAER) by coastline type vary from 0.7 m/year (maximum 10.4 m/year) for lagoons to 2.4 m/year for exposed bluffs (maximum 16.7 m/year). MAERs are much higher in silty soils (3.2 m/year) than in sandy (1.2 m/year) to gravelly (−0.3 m/year) soils. Soil organic carbon along eroding shorelines (deltas excluded) range from 12 to 153 kg/m2 of bank surface down to the water line. We assume carbon flux out from depositional delta sediments is negligible. Across the entire Alaskan Beaufort Sea Coast, estimated annual carbon input from eroding shorelines ranges from –47 to 818 Mg/km/year (Metric tones/km/year) across the 48 segments, average 149 Mg/km/year (for 34 nondeltaic segments), and total 1.8×105 Mg/year. Annual mineral input from eroding shorelines ranges from −1,863 (accreting) to 15,752 Mg/km/year, average 2,743 Mg/km/year, and totals 3.3 ×106 Mg/year