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.
Application of direct polymerase chain reaction assays for Campylobacter fetus subsp. venerealis and Tritrichomonas foetus to screen preputial samples from breeding bulls in cow-calf herds in western Canada.
The primary objectives of this study were to estimate the prevalence of Campylobacter fetus subsp. venerealis (Cfv) and Tritrichomonas foetus in breeding bulls from a sentinel cohort of cow-calf herds in western Canada and to estimate the association between positive test status and non-pregnancy. The final objective was to evaluate the application of these tests when: i) screening bulls in the absence of a recognized problem with reproductive performance, and ii) testing for diagnosis of poor pregnancy rates. The crude apparent bull prevalence for Cfv was 1.1% [95% confidence interval (CI): 0.5% to 2.1%; 8/735] and herd prevalence was 2.6% (95% CI: 0.3% to 9.0%; 2/78). The crude apparent bull prevalence for T. foetus was < 0.001% (95% CI: 0.0% to 0.5%; 0/735) and herd prevalence was < 0.001% (95% CI: 0.0% to 4.6%; 0/78). Cows from herds where at least 1 bull was test positive for Cfv were 2.35 times more likely (95% CI: 1.01% to 5.48%; P = 0.047) to not be pregnant than those with no positive bulls. Polymerase chain reaction (PCR) testing of preputial material collected into phosphate-buffered saline (PBS) was recommended for screening for T. foetus when the pre-test probability of infection was > 1%. The same test for Cfv was not recommended for screening moderate- and low-risk herds due to the high risk of false positives. Tests for both T. foetus and Cfv can be used to investigate herds with reproductive problems when also ruling out other risk factors. Regardless of the type of test used, however, 3 negative tests are required to rule out infection in high-risk situations.
Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca  2% (n=9 ) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.