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The objective of this experiment was to examine effects of adding 2 exogenous fibrolytic enzymes (EFE) to the total mixed ration (TMR) on the performance of lactating dairy cows (experiment 1) and the kinetics of ruminal degradation of the diet (experiment 2). Twelve EFE had been screened in a series of in vitro assays that identified the most potent EFE and their optimal doses for increasing the digestibility of bermudagrass. In experiment 1, 66 Holstein cows (21 ± 5 d in milk) were grouped by previous milk production and parity (45 multiparous and 21 primiparous) and assigned randomly to 1 of the following 3 treatments: (1) control (CON, untreated), (2) Xylanase Plus [2A, 1 mL/kg of TMR dry matter (DM); Dyadic International, Jupiter, FL], and (3) a 75:25 (vol/vol) mixture of Cellulase Plus and Xylanase Plus EFE (3A, 3.4 mL/kg of TMR DM; Dyadic International). The EFE were sprayed twice daily onto a TMR (10% bermudagrass silage, 35% corn silage, 5% alfalfa-orchardgrass hay mixture, and 50% concentrates; DM basis) and fed for a 14-d training and covariate period and a 70-d measurement period. Experiment 2 aimed to examine the in situ DM ruminal degradability and ruminal fermentation measurements of the diets fed in experiment 1. Three ruminally fistulated lactating Holstein cows were assigned to the diets. The experiment had a 3 × 3 Latin square design with 23-d periods. In experiment 1, application of 2A increased intakes (kg/d) of DM (23.5 vs. 22.6), organic matter (21.9 vs. 20.9), and crude protein (3.9 vs. 3.7) and tended to increase yields (kg/d) of fat-corrected milk (41.8 vs. 40.7) and milk fat (1.48 vs. 1.44). In particular, 2A increased milk yield (kg/d) during wk 3 (41.2 vs. 39.8, tendency), 6 (41.9 vs. 40.1), and 7 (42.1 vs. 40.4), whereas 3A increased milk yield (kg/d) during wk 6 (41.5 vs. 40.1, tendency), 8 (41.8 vs. 40.0), and 9 (40.9 vs. 39.5, tendency). In experiment 2, EFE treatment did not affect ruminal DM degradation kinetics or ruminal pH, ammonia-N, and volatile fatty acid concentration. Application of 2A to the bermudagrass-based TMR increased DM intake and milk production, implying that this EFE could be used to increase the performance of lactating dairy cows fed diets containing up to 10% bermudagrass. [ABSTRACT FROM AUTHOR]

Emissions from distant source areas are often imagined to provide a steady background to the emissions of whatever local sources are being studied. As part of Project MOHAVE in summer 1992, several air mass markers and an injected stack tracer were measured hourly near the Grand Canyon. Observed haze events generally coincided with transients in methylchloroform and water vapor, which we interpret as endemic tags for air from southern California and the subtropics. The results depict a dynamic regional background. [ABSTRACT FROM AUTHOR]

A commercial assay (Amplified Mycobacterium tuberculosis Direct Test, Gen Probe) which combines transcription-mediated amplification of target rRNA with amplicon detection by a chemiluminescent DNA probe for the rapid detection of Mycobacterium tuberculosis in sputum was evaluated. The test was applied to consecutively collected, NALC/NaOH processed sputum sediments from two laboratories (H and L), each serving a different population of patients with pulmonary tuberculosis. Results were compared to those of fluorochrome staining and culture. A total of 760 specimens obtained from 246 patients were used for the study. The test was positive in 141 of 144 (98 %) specimens that were fluorochrome-positive and culture-positive for Mycobacterium tuberculosis. Fifteen of 31 specimens that were fluorochromenegative, culture-positive were also assay-positive. A total of 312 specimens (100 patients) from laboratory H (prevalence = 10 %) and 448 specimens (146 patients) from laboratory L (prevalence = 34 %) were analyzed. Compared to culture, test sensitivity, specificity, positive predictive and negative predictive values were 65 %, 99 %, 94 % and 97 %, respectively, for laboratory H and 93 %, 99 %, 99 % and 97 %, respectively, for laboratory L. If the results were analyzed on the basis of at least one concordant result between the amplification assay and culture in three sputum samples per patient, then the sensitivity, specificity, positive and negative predictive values for identifying infected patients was 70 %, 99 %, 87 % and 97 %, respectively, for laboratory H, and 100 %, 98 %, 96 % and 100 %, respectively, for laboratory L. [ABSTRACT FROM AUTHOR]