Alternative Pasture Development System and Breeding Weight for Beef Heifers

Proper development of replacement beef heifers is critical and needs to be accomplished at lower costs without sacrificing reproductive performance. The current recommendations indicate heifers should reach approximately 65% of mature body weight (MBW) at breeding for successful reproduction (Patterson et al. 1992; NRC 1996). Meeting heifer maintenance and gestation nutrient requirements are getting more economically challenged for beef producers in western Canada. Therefore, producers are moving from drylot development systems where cattle are housed and fed in pens to the adoption of extensive grazing systems (Kelln et al. 2011) in field paddocks. Limited research has been conducted to determine whether inherent differences in development systems affect reproductive efficiency of heifers. The most commonly used extensive dormant season grazing system in western Canada is pasture grazing forage bales in field paddocks (Kelln et al. 2011). The objectives of this study were to determine: (1) the effects of developing heifers to a pre-breeding targeted body weight (BW) of either 55 or 62% MBW on dry matter intake (DMI), nutrient intake and reproductive efficiency; and (2) the effects of developing heifers in either field pasture paddocks (PG) or conventional drylot pens (DL) on development system cost over 2 seasons (2010-2012)

Understanding extreme quasar optical variability with CRTS: I. Major AGN flares

There is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present the results of a systematic search for major flares in AGN in the Catalina Real-time Transient Survey as part of a broader study into extreme quasar variability. Such flares are defined in a quantitative manner as being atop of the normal, stochastic variability of quasars. We have identified 51 events from over 900,000 known quasars and high probability quasar candidates, typically lasting 900 days and with a median peak amplitude of $\Delta m = 1.25$ mag. Characterizing the flare profile with a Weibull distribution, we find that nine of the sources are well described by a single-point single-lens model. This supports the proposal by Lawrence et al. (2016) that microlensing is a plausible physical mechanism for extreme variability. However, we attribute the majority of our events to explosive stellar-related activity in the accretion disk: superluminous supernovae, tidal disruption events, and mergers of stellar mass black holes.Comment: 25 pages, 18 figures, accepted for publication by MNRA

Lead in paint-contaminated residential soils with varying physicochemical properties from three large US cities: assessment of geochemical forms and recommendations on amendments for immobilization

Lead in yard soils has been recognized as the principal source of excess lead absorption among young children. The hazard imposed by soil lead is dependent on the geochemical forms of lead in soils. Soil properties such as pH, soil organic matter, clay, and carbonate content influence the geochemical forms of lead in soil. This study was conducted to investigate the correlation between soil properties and the geochemical speciation of lead in lead paint-contaminated residential soils from three major US cities. A comprehensive field survey was conducted, involving the collection of soils from ten houses in each of the cities: Baltimore, San Antonio, and Detroit. The influence of soil properties on geochemical speciation was analyzed to identify effective immobilization amendments for each soil type. Results showed that soils collected from San Antonio were slightly alkaline, whereas those from Baltimore were slightly acidic. Soils collected from Detroit were neutral to mildly alkaline in pH. San Antonio soils had relatively high soil salinity, high clay content, moderate to high soil organic matter (SOM), and high total carbon (TC). In contrast, soils collected from Baltimore had lower salinity and clay content, low SOM, and total carbon. Soils from Detroit exhibited relatively high salinity, clay, SOM, and TC contents. The average total soil lead concentrations were as follows; San Antonio 4,073 mg/kg, Baltimore 2,706 mg/kg, and Detroit 850 mg/kg. Geochemical speciation studies revealed significant differences in lead distribution among the studied soils. San Antonio soils exhibited high carbonate-bound and organic matter-bound fractions, while Baltimore soils had elevated soluble + exchangeable fractions. Detroit soils showed substantial lead in organic matter-bound fractions. Correlation analysis showed that the soil properties influencing exchangeable lead, were pH, total Al, and total Ca for San Antonio soils; pH and total P for Baltimore soils; and SOM and total Al for Detroit soils. Correlation analysis showed that there is a significant negative correlation (p \u3c 0.05) between exchangeable lead and total Al (r = −0.653), and total Ca (r = −0.438) for San Antonio soils; pH (r = −0.286) and total p (r = −0.314) for Baltimore soils; and SOM (r = −0.628) and total Al (r = −0.408) for Detroit soils. Based on these results, the best potential immobilization amendments for each of these cities were predicted

A possible close supermassive black-hole binary in a quasar with optical periodicity

Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic, can be due to a variety of physical mechanisms, and is well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report on the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302-102 with a mean observed period of 1,884 $\pm$ 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of $\sim9$ years. While the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution.Comment: 19 pages, 6 figures. Published online by Nature on 7 January 201

Accumulation pattern of total nonstructural carbohydrate in strawberry runner plants and its influence on plant growth and fruit production

The pattern of total nonstructural carbohydrate (TNC) accumulation in strawberry (Fragaria ananassa Duch.) nursery runner plants, cv. eCamarosaf, was determined for three growing seasons. Plant growth and fruit production patterns were also evaluated. The experiments were carried out on plants propagated in high latitude (41‹50' N) and high elevation (1292 m) nurseries in Siskiyou County, California. Plants were sampled beginning in late summer through early autumn and analyzed for dry mass (DM) and TNC. Plants from different digging dates were established in growth chambers (GC) at UC Davis or fruit evaluation plots in Irvine, California. In the nursery, TNC concentration in storage tissues increased steadily from the second week of September to the third week of October, and crown and root TNC concentration was positively correlated with the accumulation of chilling units (hours .7.2‹C). The root TNC concentration consistently increased from 6 to 10% DM from mid-September to the first week of October. Transplant growth and fruiting pattern were affected by digging date. Overall, the roots were more sensitive to chilling in terms of TNC accumulation, than the crowns. Therefore, roots would be the appropriate organ for assessing TNC status and potential digging dates of strawberry nursery runner plants early in the fall.Key words: Transplant, carbohydrate, chilling, growth analysis

Sequenced-Based Paternity Analysis to Improve Breeding and Identify Self-Incompatibility Loci in Intermediate Wheatgrass (Thinopyrum Intermedium)

Key Message Paternity assignment and genome-wide association analyses for fertility were applied to a Thinopyrum intermedium breeding program. A lack of progeny between combinations of parents was associated with loci near self-incompatibility genes. Abstract In outcrossing species such as intermediate wheatgrass (IWG, Thinopyrum intermedium), polycrossing is often used to generate novel recombinants through each cycle of selection, but it cannot track pollen-parent pedigrees and it is unknown how self-incompatibility (SI) genes may limit the number of unique crosses obtained. This study investigated the potential of using next-generation sequencing to assign paternity and identify putative SI loci in IWG. Using a reference population of 380 individuals made from controlled crosses of 64 parents, paternity was assigned with 92% agreement using Cervus software. Using this approach, 80% of 4158 progeny (n = 3342) from a polycross of 89 parents were assigned paternity. Of the 89 pollen parents, 82 (92%) were represented with 1633 unique full-sib families representing 42% of all potential crosses. The number of progeny per successful pollen parent ranged from 1 to 123, with number of inflorescences per pollen parent significantly correlated to the number of progeny (r = 0.54, p \u3c 0.001). Shannon’s diversity index, assessing the total number and representation of families, was 7.33 compared to a theoretical maximum of 8.98. To test our hypothesis on the impact of SI genes, a genome-wide association study of the number of progeny observed from the 89 parents identified genetic effects related to non-random mating, including marker loci located near putative SI genes. Paternity testing of polycross progeny can impact future breeding gains by being incorporated in breeding programs to optimize polycross methodology, maintain genetic diversity, and reveal genetic architecture of mating patterns