Hayland conversion to wheat production in semiarid eastern Montana: tillage, yield and hay production comparisons

When converting grass- and haylands to cultivated crop production, care must be taken to conserve and maintain soil resources while considering economic issues. Methods of breaking sod can have a bearing on erosivity, physical and chemical properties of soils, and cost of production. Our objective was to compare three methods of converting crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.] hayland to wheat (Triticum aestivum L.) production vs. leaving the land for hay production. We initiated a study in 1990 on Dooley sandy loam (fine-loamy, mixed Typic Argiboroll) near Froid in semiarid eastern Montana, USA. Plots, replicated three times, were 12- by 30-m oriented east to west on a north-facing slope. We converted sod to cultivated crop production by: (1) moldboard plow, (2) toolbar with sweeps, (3) herbicides (no-till). Plots were fallowed until spring 1991 and then seeded to spring wheat each of the next four years. All wheat plots were fertilized with 224 kg ha⁻¹ of 18-46-0 in 1991 and 1992, and 34 kg ha⁻¹ nitrogen as 34-0-0 in 1993 and 1994. Grass was either fertilized same as wheat or not fertilized. Wheat yields averaged 2540 kg ha⁻¹ on tilled treatments and 2674 kg ha⁻¹ on no-till. Fertilized grass consistently out-yielded unfertilized, and averaged 3.2 Mg ha⁻¹ vs. 1.8 Mg ha⁻¹. Toolbar with sweeps had highest economic return of US$169.48 ha⁻¹ to pay for land, labor, and management. Moldboard plow had US$162.05 ha⁻¹. Because of herbicide costs, no-till only returned US$148.64 ha⁻¹. Unfertilized grass hay returned US$67.68 ha⁻¹ and fertilized grass hay, US$97.95 ha⁻¹. Results may be tempered because our wheat yields were high: a 2016 kg ha⁻¹ wheat yield would have returned the same as fertilized grass. Before converting grass- and hay-lands to small grains production, consideration must be given to such variables as sod conversion methods, management practices, labor requirements, market conditions, total precipitation and its temporal distribution, soil conditions, growth environment, soil conservation, and economics.     

A long-snouted predatory dinosaur from africa and the evolution of spinosaurids

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.     

Tracking the long-term decline and recovery of an isolated population

Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens.     

The effect of life history events on carcass merit and price of cull dairy cows

Cull dairy cows contribute almost 10% of national beef production in the United States. However, different factors throughout the life of dairy cows affect their weight and overall body condition as well as carcass traits, and consequently affect their market price. Therefore, the objectives of this study were: (1) to assess relationships between price ratio and carcass merit of cull dairy cows sold through several sites of an auction market and (2) to investigate the effect of animal life history events and live weight on sale barn price (BP) and price ratio (as a measure of relative price), as an indicator of carcass merit. Data from 4 dairy operations included 3,602 cull dairy cow records during the period of 2015 to 2019. Life history events data were collected from each dairy operation through Dairy Comp software; live weight and price were obtained periodically from the auction market, and the carcass data were provided by a local packing plant. Cow price in dollars per unit of live weight ($/cwt) and price ratio were the 2 outcome variables used in the analyses. Price ratio was created aiming to remove seasonality effects from BP (BP divided by the national average price for its respective month and year of sale). The association between price ratio and carcass merit traits was investigated using canonical correlation analysis, and the effect of life history events on both BP and price ratio was inferred using a multiple linear regression technique. More than 70% of the cows were culled in the first 3 lactations, with an average live weight of 701.5 kg, carcass weight of 325 kg, and dressing percentage of 46.3%. On average, cull cows were sold at $57.0/cwt during the period considered. The canonical correlation between price ratio and carcass merit traits was 0.76, indicating that price ratio reflected carcass merit of cull cows. Later lactations led to lower BP compared with cows culled during the first 2 lactations. Injury, and leg and feet problems negatively affected BP. Productive variables demonstrated that the greater milk production might lead to lower cow prices. A large variation between farms was also noted. In conclusion, price ratio was a good indicator of carcass merit of cull cows, and life history events significantly affected sale BP and carcass merit of cull cows sold through auction markets.     

Transstadial and intrastadial experimental transmission of Ehrlichia canis by male Rhipicephalus sanguineus

The acquisition and transmission of rickettsial pathogens by different tick developmental stages has important epidemiological implications. The purpose of this study was to determine if male Rhipicephalus sanguineus can experimentally acquire and transmit Ehrlichia canis in the absence of female ticks. Two trials were performed where nymphal and male R. sanguineus were simultaneously acquisition fed on the same infected donor hosts, and transstadially or intrastadially exposed male ticks were fed on separate pathogen-free dogs as a test for transmission. A single-step p30-based PCR assay was used to test canine and tick hosts for E. canis infections before and after tick feeding. E. canis was detected after either intrastadial or transstadial passage in male ticks, the organism remained detectable in both tick groups after transmission feeding, and both tick groups transmitted the rickettsia to susceptible dogs. Infection of dogs via tick feeding resulted in milder clinical signs and lower antibody titers than intravenous inoculation of carrier blood, but further investigation is needed to understand the mechanisms responsible for this observation. These results demonstrate that male R. sanguineus can take multiple feedings, and that they can both acquire and transmit E. canis in the absence of female ticks. This tick development stage could be important in transmission of E. canis, and perhaps related pathogens, between vertebrate hosts under natural and experimental conditions.     

Cotton response to short-term waterlogging imposed with a water-table gradient facility

Waterlogging of field-grown plants can occur either when the surface of slowly permeable soils is inundated or when the water-table rises so that part or all of the root zone is saturated. The effects of short-term waterlogging on field crop growth and yield have not been well quantified. To study these effects, a sloping, repacked slab of soil underlain by an impermeable membrane was constructed. The sloping plot (45 m long × 6 m wide × 0.6 m deep) was flooded by introducing water through a drainage network and gravel bed so that a gradient of water-table depth ranging from 0.1 m above to 0.66 m below the soil surface was obtained. Cotton (Gossypium hirsutum cv. Deltapine 61) was grown in the facility and the responses of plants to two periods of flooding were monitored. Soil matric potential and oxygen partial pressure data indicated that plants were subjected to a continuum of conditions ranging from complete inundation to no water-table within the root zone.The first flooding event began 82 days after sowing just prior to the main flowering period. Plants with more than 55% of their root system below the water table showed decreased leaf growth about 3–4 days after the flooding started with visible wilt symptoms and decreased leaf water potential observed on days 7 and 8 of flooding. In the second flooding event (131 days after sowing), plants showed no signs of waterlogging stress apart from reduced leaf growth despite 16 days of flooding. Plant growth response was probably more the result of reduced nutrient status (mostly nitrate) rather than a water deficit stress effect with some plant acclimatization between the first and second flooding event. Seed cotton yield data indicated that the observed stress during the first flooding event may have promoted reproductive growth in plants where the short-term water-table was greater than 0.2 m below the soil surface.