Cow attributes, herd management, and reproductive history events associated with the risk of nonpregnancy in cow-calf herds in Western Canada.
To identify herd management and cow characteristics associated with the reproductive success of cow-calf herds in Western Canada, 33,391 beef cows were followed from the beginning of the breeding season in 2001 through pregnancy testing in 2002. Breeding management and cow-level risk factors such as age, body condition score (BCS), and previous reproductive history, were measured through a series of herd visits by project personnel and records maintained by the herd owner. Pregnancy status was measured in 205 herds in the fall of 2001 and again in 200 herds in the fall of 2002. Cows least likely to be pregnant in the fall of the year were 10 years old or older, exposed to a bull less than 84 days, had a BCS ≤5 of 9 at pregnancy testing, <5 of 9 before calving, and lost condition between calving and the start of the breeding season, or had a prebreeding BCS <5 of 9 with a loss of condition between breeding and pregnancy testing. Other factors identified that decreased the likelihood of pregnancy in at least one of the 2 years included being a heifer or being a cow exposed to breeding after her first calf, and using a single bull on breeding pasture. Cows vaccinated for bovine viral diarrhea virus and infectious bovine rhinotracheitis and bred on community pastures were more likely to be pregnant than cows that were not vaccinated and bred on community pastures. Cows bred on community pastures that were not vaccinated were also less likely to be pregnant than cows that were not on community pastures regardless of vaccination status. Calving-associated events such as twin birth, Cesarean section or malpresentation, problems such as uterine prolapse or retained placentas, abortion or calf death within 1 hour after birth, or calving late after the start of the breeding season, were also associated with fewer pregnancies after accounting for all other factors.
Risk of Nonpregnancy, Risk of Disposal for Pregnant Cows, and Duration of the Calving Interval in Cow-Calf Herds Exposed to the Oil and Gas Industry in Western Canada
To determine potential associations between emissions from oil and gas field facilities and the reproductive success of cow-calf herds in Western Canada, researchers followed approximately 33,000 beef cows from the beginning of the breeding season in 2001 through pregnancy testing in 2002. They prospectively measured exposure to sulfur dioxide, hydrogen sulfide, and volatile organic compounds (VOCs) by using data from passive air monitors installed in pastures and linked to the locations of individual animals. They used the density of oil and gas well sites surrounding each pasture as an additional measure of exposure. The researchers measured the risk of nonpregnancy in cattle in 205 herds in fall 2001 and 200 herds in fall 2002, and they determined the interval between the dates of calving in 2001 and 2002 for all cows calving in both years from 202 herds. The risk of disposal in pregnant cows was measured as the risk of removal from inventory for any reason other than nonpregnancy between pregnancy testing in 2001 and calving in 2002. There was no evidence that exposure to sulfur dioxide or VOCs measured as benzene and toluene increased the odds of nonpregnancy or disposal for pregnant cows. Density of oil and gas well sites was not related to the odds of nonpregnancy in either 2001 or 2002 or the odds of disposal for pregnant cows. During the first month after bull contact, exposures to increasing concentrations of sulfur dioxide, VOCs measured as toluene, and the density of oil and gas well sites were also not associated with an increase in the 2001-2002 breeding-to-calving interval. However, there was an estimated 3.0-day increase in the breeding-to-calving interval for mature cows exposed to benzene concentrations in the highest quartile of exposure (> 0.236 μg/m3) compared with those cows exposed to benzene concentrations in the lowest quartile of exposure (< 0.082 μg/m3).
LABORATORY AND FIELD TESTING OF SEED SPACING UNIFORMITY FOR SUGARBEET PLANTERS
Five planter configurations were evaluated for seed spacing uniformity at three field speeds using a seed 
location method in the field and a laboratory method involving an opto-electronic sensor system. Planter seed spacing 
uniformity was described using the Coefficient of Precision (CP3) measure. Results showed that CP3 measures 
determined using the laboratory test method were significantly different from those determined using the field test method. 
This indicated the laboratory test method cannot be used to predict planter seed spacing uniformity in the field. Seed 
spacing uniformity determined in laboratory tests was higher than, or equal to, seed spacing uniformity determined in 
field tests. This indicated the laboratory test method may be useful to screen out planters or planter units with poor 
uniformity of seed metering. Field testing of the planters that perform well in laboratory tests must be conducted to 
adequately determine the seed spacing uniformity of those planters in the field. Results from laboratory and field tests 
could be useful in determining areas for improvement of planters or planter units.