Whole-plant corn was harvested at 33 (normal) and 41% (moderately high) dry matter (DM) and ensiled in quadruplicate 20-L laboratory silos to investigate the effects of Lactobacillus buchneri 40788 (LB) or L. plantarum MTD-1 (LP) alone, or in combination, on the fermentation and aerobic stability of the resulting silage. Aerobic stability was defined as the amount of time after exposure to air for the silage temperature to reach 2 degrees C above ambient temperature. The chopped forage was used in a 2 x 2 x 2 factorial arrangement of treatments: normal and moderately high DM contents, LB at 0 (untreated) or 4 x 10(5) cfu/g of fresh forage, and LP at 0 or 1 x 10(5) cfu/g. After 240 d of ensiling, corn silage harvested at the moderately high DM had higher pH, higher concentrations of ethanol, and more yeasts compared with the silage ensiled at the normal DM content. Inoculation with LB did not affect the concentration of lactic acid in silages with a moderately high DM, but decreased the concentration of lactic acid in the silage with normal DM. Higher concentrations of acetic acid were found in the silage treated with LB compared with those not treated with this organism. Inoculation with LP increased the concentration of lactic acid only in the silage with the normal DM content. The concentration of acetic acid was lower in silage treated with LP with a moderately high DM content, but greater in the silage treated with LP with the normal DM content when compared with silages without this inoculant. Appreciable amounts of 1,2-propanediol (average 1.65%, DM basis) were found in all silages treated with LB regardless of the DM content. The addition of L. buchneri increased the concentration of NH(3)-N in silages but the addition of L. plantarum decreased it. Aerobic stability was improved in all silages treated with LB, with greater aerobic stability occurring in the silage with moderately high DM compared with silage with normal DM content. Inoculation with LP had no effect on aerobic stability. There were no interactions between L. buchneri and L. plantarum for most fermentation products or aerobic stability of the silages. This study showed that inoculating whole-plant corn with L. buchneri 40788 or L. plantarum MTD-1 has different beneficial effects on the resulting silage. There appear to be no major interactions between these organisms when added together to forage. Thus, there is potential to add both organisms simultaneously to improve the fermentation and aerobic stability of corn silage.

A meta-analysis was conducted to examine potential empirical relationships between dietary cation-anion difference (DCAD) (Na + K - Cl) and the response of lactating dairy cows. The database was developed from 12 studies published between 1984 and 1997 that included a total of 17 trials, 69 dietary treatments, and 230 cows. Results indicated that DCAD affected performance of lactating dairy cows. Maximum milk yield and feed intake were reached when DCAD was 34 and 40 meq/100 g of feed dry matter, respectively. Blood pH and HCO3 concentrations increased with DCAD, indicating an improved acid-base balance of lactating dairy cows. Changes in urinary pH and urinary excretion of Na, K, and Cl were consistent with varying DCAD, thus dietary acidity or alkalinity. The effects of DCAD were likely mediated via modification of acid-base status in the cows.

An experimental (7B) and a commercial (AMA) formulation of enzymes, both primarily with alpha-amylase activity, were evaluated for activity at various pH values, stability in ruminal fluid, the potential to improve in vitro ruminal fermentations, and the potential to improve production performance of lactating cows. When incubated (40 degrees C) in buffer with a pH between 5.4 and 6.0, 7B had about 10 to 25 times greater amylase activity than AMA, and enzyme activity in this range increased by 100% for 7B, whereas activity decreased by about 26% for AMA. Both formulations maintained enzyme activity when they were incubated in in vitro ruminal fermentations for 24 h. After 6 h of ruminal in vitro fermentation, additions of 7B resulted in linear increases in apparent total volatile fatty acid production for flint and dent corn but had no effect on floury corn. In a lactation trial, 28 Holstein cows (68 +/- 31 d in milk, 46.9 +/- 9.1 kg of milk/d) were fed a total mixed ration (TMR) supplemented with nothing (CON), a low dose of 7B [7BL, 0.88 mL/kg of TMR dry matter (DM)], a high dose of 7B (7BH, 4.4 mL/kg of TMR DM), or AMA (0.4 g/kg of TMR DM). The experiment was conducted as a 4. 4 Latin square design with 21-d periods. Cows fed 7BL, 7BH, and AMA ate similar amounts of DM, and cows fed the latter 2 diets consumed more DM than did cows fed CON. Cows fed 7BL produced more milk than cows fed CON and 7BH, but produced similar amounts to cows fed AMA. The production of 3.5% fat-corrected milk was greater from cows fed 7BL and AMA compared with cows fed CON. The percentages of milk fat and milk protein were unaffected by treatment. Total-tract digestion of DM and organic matter were greater for cows fed 7BL compared with those fed CON. The addition of exogenous amylase enzymes to the diets of lactating dairy cows has the potential to improve animal productivity.

The ecology of the uncultured, but large and morphologically conspicuous, rumen bacterium Oscillospira spp. was studied. Oscillospira-specific 16S rRNA gene sequences were detected in North American domestic cattle, sheep from Australia and Japan, and Norwegian reindeer. Phylogenetic analysis of the sequences obtained allowed definition of three operational taxonomic units within the Oscillospira clade. Consistent with this genetic diversity, we observed atypical smaller morphotypes by using an Oscillospira-specific fluorescence in situ hybridization probe. Despite the visual disappearance of typical large Oscillospira morphotypes, the presence of Oscillospira spp. was still detected by Oscillospira-specific PCR in the rumen of cattle and sheep. These observations suggest the broad presence of Oscillospira species in various rumen ecosystems with the level, and most likely the morphological form, dependent on diet. An ecological analysis based on enumeration of the morphologically conspicuous, large-septate form confirms that the highest counts are associated with the feeding of fresh forage diets to cattle and sheep and in two different subspecies of reindeer investigated.Morphologically unique, large bacteria of the genus Oscillospira, which have not been grown in pure culture yet, can be routinely detected microscopically in the rumen contents of cattle and sheep (11,18). A number of Oscillospira spp. are responsive to the advent of green pastures and fluctuate seasonally (13, 17) (see also Table 1). The only species of Oscillospira described in Bergey's Manual of Systematic Bacteriology (8) is Oscillospira guilliermondii, and this entry refers to the original morphological description by Chatton and Perard in 1913. Warner (34) proposed that at least two strains or species be included in the Oscillospira group based on cell diameter and the tendency to form spores as the main characteristic differences. This implies that there are different morphological forms or species related to different diets or in different gut ecosystems.Detection and identification of microbial populations are the most basic prerequisites for microbial ecology studies. Over the last decade, several molecular techniques have been developed that when applied to the rumen microbiota have revealed enormous microbial diversity not recognized previously because of limitations and biases inherent in the cultivation approach (24,(30)(31)(32)37). The cultivation-independent approach provides technology for detection and monitoring of microorganisms such as Oscillospira, for which growth requirements are unknown and undetermined. The only requirement for the development of molecular detection techniques is the availability of a marker molecule. Fortunately, several 16S rRNA gene sequences have recently been retrieved from this large bacterium isolated by flow cytometric sorting (39), and this enabled the design of various molecular probes for detection and monitoring. We designed and validate here PCR and PCR-denaturing gradient gel electroph...