A field investigation of the economic impact of respiratory disease in feedlot calves

A trial involving 512 beef calves was conducted in a commercial research feedlot to determine the effect of bovine respiratory disease (BRD) on performance parameters and carcass characteristics. Two hundred and fifty-six calves that were deemed to be “sick” (S) from BRD were allocated to 16 pens and 256 calves that were considered to be “well” (W) were allocated to another 16 pens. The outcome variables that were measured included average daily gain (ADG), daily dry matter intake (DDMI), dry matter intake to gain ratio (DM:G), BRD treatment rate, death loss, carcass traits, and net profit per pen.

The data were partitioned into several time intervals including processing (P) to day −1, day 0 to day 27, day 28 to day 55, day 56 to day 83, day 84 to day 111, day 112 to day 139, day 140 to slaughter, day 0 to slaughter (0-Slaugh), and processing to slaughter (P-Slaugh). However, the most important interval was from processing to slaughter.

For the interval P-Slaugh, there were no significant (p≥0.05) differences between the S and W groups with respect to ADG and DM:G. Also, for the interval 0-Slaugh, the DDMI was similar for both groups. There were no significant (p≥0.05) differences between the S and W groups for carcass weight, average fat, grade fat, rib eye area, marbling score, cutability estimate, or carcass grade distribution.

The BRD treatment rates in the S and W groups were 6.6% and 4.7%, respectively. The mortality rates in the S and W groups were 0.78% and 0.39%, respectively. Also, there were no deaths attributable to BRD in either group.

In the economic model, there was no significant (p≥0.05) difference between the S and W groups with respect to net profit per pen.

We conclude that this trial did not validate the concept that BRD impacts performance parameters, because a sufficient disease challenge was not present. However, this study provides several observations that will enhance the experimental design of future studies that attempt to quantify the total economic impact of BRD.

     

FUSARIUM-ID v. 1.0: A DNA Sequence Database for Identifying Fusarium

One of the greatest impediments to the study of Fusarium has been the incorrect and confused application of species names to toxigenic and pathogenic isolates, owing in large part to intrinsic limitations of morphological species recognition and its application. To address this problem, we have created FUSARIUM-ID v. 1.0, a publicly available database of partial translation elongation factor 1-alpha (TEF) DNA sequences, presently representing a selected sample of the diversity of the genus diversity, with excellent representation of Type-B trichothecene toxin producers, and the Gibberella fujikuroi, Fusarium oxysporum and F. solani species complexes. Users can generate sequences using primers that are conserved across the genus, and use the sequence as a query to BLAST the database, which can be accessed at http://fusarium.cbio.psu.edu, or in a phylogenetic analysis. Correct identification of a known species in these groups often can be performed using this gene region alone. This growing database will contain only vouchered sequences attached to publicly available cultures. In the future, FUSARIUM-ID will be expanded to include additional sequences, including multiple sequences from the same species, sequences from new and revised species, and information from additional genes.     

Punch planting, flame weeding and stale seedbed for weed control in row crops

Punch planting is introduced as a new method to reduce weeds within rows in organically grown crops. In this method a hole is punched in the soil, and a seed is dropped into it, without seedbed preparation and soil disturbance outside the hole. In 2 years, punch planting with flame weeding, normal planting with flame weeding and normal planting without flame weeding were compared in fodder beet for five planting dates. Each planting date represented a lag‐period since establishment of the stale seedbed. Over all planting times and years, punch planting with flame weeding reduced intra‐row weed densities by 30% at the two to four leaf stage of fodder beet compared with normal drilling with flame weeding. Punch planting with flame weeding also reduced intra‐row weed densities by 50% compared with normal drilling without flame weeding. In general, there was no improved performance of punch planting with flame weeding over years by later planting, but delayed planting reduced intra‐row weed densities significantly. Over 2 years, 240 day degrees Celsius (4 weeks) planting delay reduced intra‐row weed densities in the range of 68–86% depending on plant establishment procedure. Punch planting with flame weeding offers a promising method of weed control in organic farming.     

Quantitative assessment of the treescape and cityscape of Nanjing,China

The urban landscape is by nature the result of many cultural and natural factors and processes. Cityscape associated with land attributes and human activities expresses a city's social and economic functions. Treescape in the form of species composition, tree dimension and tree performance echoes ecological and environmental functions. The cityscape can be denoted by urban factors, such as tree growing-space condition, tree management regime, human activities and planting history. The hypothesis that the cityscape plays a key role in molding the treescape is tested. Nanjing, an east China city notable for its high tree coverage, is chosen as the study area. A quantitative method has been developed to assess the relationship between cityscape and treescape. Based on statistical analyses on the surveyed results of 6527 trees and related cityscape attributes, this paper explores the pertinent patterns and underlying factors of treescape variations. Species composition has the strongest association with cityscape. Roadside and factories have lower species diversity. Residential and industrial land uses show smaller tree dimension. Trees in residential, commercial, heavy industrial land-uses perform below par. A three-way classification has been developed to examine the effects of urban factors on treescape at different cityscape scales. At the small scale, a well-vegetated groundcover will ensure better tree performance and a lower management burden. The medium-scale cityscape (land-use and habitat) is preferred in the study of treescape attributes and their spatial variations, and is suitable for urban tree planning and management. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of Sowing Date, Host Cultivar, and Race of Fusarium oxysporum f. sp. ciceris on Development of Fusarium Wilt of Chickpea

ABSTRACT Microplots experiments were carried out at Córdoba, southern Spain, from 1986 to 1989 to determine the effects of sowing date in the management of Fusarium wilt of chickpea as influenced by virulence of the pathogen race and by cultivar susceptibility. A total of 108 epidemics of the disease were described, analyzed, and compared to assess the degree of disease control. The epidemics were characterized by five curve elements: final disease intensity index (DII), standardized area under DII progress curve, time to epidemic onset, time to inflection point (t(ip)), and the DII value at t(ip), the last two parameters being estimates from the Richards function adjusted by nonlinear regression analysis. The structure of Fusarium wilt epidemics was examined by conducting multivariate principal components and cluster analyses. From these analyses, three factors accounting for 98 to 99% of the total variance characterized the DII progress curves and provided plausible epidemiological interpretations. The first factor included the t(ip) and the time to disease onset and can be interpreted as a positional factor over time. This factor accounted for the largest proportion of the total variance and may, therefore, be considered as the main factor for analysis of Fusarium wilt epidemics. The second factor concerns the standardized area under DII progress curves and the final DII of the epidemics. The third factor identified the uniqueness of the estimated value for the point of inflection of the DII progress curve over time. Our results indicate that for each year of experiment epidemic development was related mainly to the date of sowing. Thus, for chickpea crops in southern Spain, advancing the sowing date from early spring to early winter can slow down the development of Fusarium wilt epidemics, delay the epidemic onset, and minimize the final amount of disease. However, the net effect of this disease management practice may also be influenced, though to a lesser extent, by the susceptibility of the chickpea cultivar and the virulence and inoculum density of the Fusarium oxysporum f. sp. ciceris race.