Parity, body condition score (BCS), and dry matter intake (DMI) data of 699 Holsteins fed 49 different diets during the final 3 wk of gestation (prefresh transition period) were compiled from 16 experiments conducted at eight universities. The objectives of this study were to determine the effects of animal and dietary factors on DMI and to elucidate interactions between animal and dietary factors and among dietary factors on DMI during the prefresh transition period. Animal factors examined were parity and BCS, whereas dietary factors examined were rumen undegradable protein (RUP), rumen degradable protein (RDP), neutral detergent fiber (NDF), and ether extract (EE). DMI decreased 32% during the final 3 wk of gestation, and 89% of that decline occurred during the final week of gestation. Day of gestation, animal factors, and dietary factors accounted for 56.1, 19.7, and 24.2% of explained variation in DMI, respectively, and R2 of this linear multivariable model was 0.18. Cows had higher DMI than heifers. DMI decreased linearly as BCS, RUP, and NDF increased, decreased quadratically as EE increased, and increased quadratically as RDP increased. Moreover, the magnitude of DMI depression as animals approached parturition was affected by characteristics of animals and dietary nutrient composition. There were significant parity x EE, BCS x NDF, RUP x NDF, RDP x NDF, NDF x EE, and RUP x EE interactions on DMI. In conclusion, parity, BCS, and concentrations of organic macronutrients in diets affected DMI during the prefresh transition period, and the magnitude of DMI depression as animals approached parturition.

Boreal black spruce forests typically have a dense ground cover of bryophytes. The two main bryophyte groups in boreal black spruce forests, feathermoss and Sphagnum, have ecophysiological characteristics that influence the biogeochemical cycles of black spruce forests differently. The objective of this study was to examine the environmental controls of ground cover composition and net primary production (NPP) of feathermoss and Sphagnum in a boreal black spruce forest in central Saskatchewan. The fraction of Sphagnum ground cover was positively correlated to canopy photosynthetically active radiation (PAR) transmittance (r =0.48, P=0.03), but the fraction of feathermoss ground cover was negatively correlated to canopy PAR transmittance in plots where Sphagnum was present (r=0.87, P<0.0001). Sphagnum presence was inversely correlated (P=0.0001) to water table index, defined as water table depth relative to the peat layer, while feathermoss occurred in a wider range of microenvironments. Average NPP for 1998 was more than three times greater for Sphagnum (77 g C m year) than feathermoss (24 g C m year), but the average bryophyte NPP for 1998 was 25 g C m year because feathermoss was the dominant ground cover. The large, but differing, peat carbon content of Sphagnum- versus feathermoss-dominated boreal forests and peatlands necessitates the need to accurately quantify fraction ground cover. Additional validation of the empirical models between environmental variables and fraction ground cover of bryophytes is necessary, but the reported relationships offer an approach to model carbon dynamics of bryophytes in boreal forests and peatlands.

Dysplastic hips in young dogs were significantly improved by JPS.

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Analytical methods that predict the endurance of structural wood members in a fire are based on the reduction of the cross section of the member caused by wood being charred. To define the charring rate in terms of more fundamental properties, empirical models were established. Eight species were tested for charring rates and material properties. Regression analysis was used to develop the models. The predictor variables for the initial factorial design included density, moisture content, treatability, and hardwood-softwood classification. The addition of char contraction simplified the model and reduced the predictor variables to the char contraction factor, density, and moisture content. Our results show the importance of surface recession and moisture content to wood charring.

This study examined the effects of carbon dioxide (CO2)-, ozone (O3)-, and genotype-mediated changes in quaking aspen (Populus tremuloides) chemistry on performance of the forest tent caterpillar (Malacosoma disstria) and its dipteran parasitoid (Compsilura concinnata) at the Aspen Free-Air CO2 Enrichment (FACE) site. Parasitized and non-parasitized forest tent caterpillars were reared on two aspen genotypes under elevated levels of CO2 and O3, alone and in combination. Foliage was collected for determination of the chemical composition of leaves fed upon by forest tent caterpillars during the period of endoparasitoid larval development. Elevated CO2 decreased nitrogen levels but had no effect on concentrations of carbon-based compounds. In contrast, elevated O3 decreased nitrogen and phenolic glycoside levels, but increased concentrations of starch and condensed tannins. Foliar chemistry also differed between aspen genotypes. CO2, O3, genotype, and their interactions altered forest tent caterpillar performance, and differentially so between sexes. In general, enriched CO2 had little effect on forest tent caterpillar performance under ambient O3, but reduced performance (for insects on one aspen genotype) under elevated O3. Conversely, elevated O3 improved forest tent caterpillar performance under ambient, but not elevated, CO2. Parasitoid larval survivorship decreased under elevated O3, depending upon levels of CO2 and aspen genotype. Additionally, larval performance and masses of mature female parasitoids differed between aspen genotypes. These results suggest that host-parasitoid interactions in forest systems may be altered by atmospheric conditions anticipated for the future, and that the degree of change may be influenced by plant genotype.

A field study evaluated the stopping characteristics of vehicles 2.5 to 5.5 s upstream of signalized intersections at the start of a yellow interval, a region typically considered drivers' indecision zone or dilemma zone. Characteristics included brake-response times for first-to-stop vehicles, deceleration rates for first-to-stop vehicles, distinguishing characteristics and prediction of first-to-stop versus last-to-go events, and distinguishing characteristics and prediction of red-light-running events. Consumer-grade video cameras temporarily installed at four high-speed and two low-speed intersections in the Madison, Wisconsin, area recorded dilemma zone vehicles. Several factors were measured for each last-to-go (n = 435) and first-to-stop (n = 463) vehicle in each lane during each yellow interval, including approach speed; distance upstream at start of yellow; brake-response time; deceleration rate; vehicle type; headway; tailway; action of vehicles in adjacent lanes; presence of side-street vehicles, pedestrians, bicycles, or opposing vehicles waiting to turn left; flow rate; length of yellow interval; and cycle length. The observed 15th, 50th, and 85th percentile brake-response times for first-to-stop vehicles were 0.7, 1.0, and 1.6 s, respectively; their observed deceleration rates were 7.2, 9.9, and 12.9 ft/s2, respectively. Vehicles were more likely to go through than to stop under the following conditions: shorter estimated travel time to intersection at start of yellow; longer yellow interval; the subject was a heavy vehicle (truck, bus, recreational vehicle); absence of side-street vehicles, bicycles, pedestrians, and opposing left-turn vehicles; and presence of vehicles in adjacent lanes that went through. Heavy vehicles were more likely than passenger vehicles to run a red light. Vehicles were more likely to run a red light when vehicles in adjacent lanes that also went through were present and when side-street vehicles, bicycles, pedestrians, and opposing left-turn vehicles were absent.

No abstract