Several microorganisms and one chemical preservative were tested for their effects on the fermentation and aerobic stability of corn silage. Whole-plant corn (one-half milk line, 31.3% dry matter) was ensiled in quadruplicate 20-L laboratory silos untreated or after the following treatments: Lactobacillus buchneri at 1 x 10(5) and 1 x 10(6) cfu/g of fresh forage; two different strains of L. plantarum, each at 1 x 10(6) cfu/g; and a buffered propionic acid-based product at 0.1% of fresh forage weight. After 100 d of ensiling, silage treated with L. buchneri (1 x 10(6) cfu/g) had a lower concentration of lactic acid compared with the untreated silage, but was similar to other treated silages. The silage treated with the high (1 x 10(6) cfu/g), but not the moderate rate (1 x 10(5) cfu/g) of L. buchneri also had a greater concentration of acetic acid (3.60%) and less yeasts (2.01 log cfu/g) when compared with other treatments (average of 1.88% acetic acid and 5.85 log cfu of yeasts/g). Silages treated with L. plantarums, the moderate rate of L. buchneri, and the chemical preservative took longer to heat than untreated silage when exposed to air, but improvements were numerically small (6.3 to 10.5 h). In contrast, silage treated with the high rate of L. buchneri never heated throughout a 900-h period of monitoring. Inoculating corn silage with 1 x 10(6) cfu/g of L. buchneri resulted in a more heterolactic fermentation and dramatically improved the aerobic stability of corn silage.

Whole-plant barley (39.4% dry matter) was treated with various chemical and biological additives to assess their effects on silage fermentation and aerobic stability. Treatments were untreated forage, forage treated with several amounts of Lactobacillus buchneri and enzymes (L. buchneri at 1 x 10(5), 5 x 10(5), and 1 x 10(6) cfu/g of fresh forage), forage treated with an inoculant containing (Lactobacillus plantarum, Pediococcus pentosaceus, Propionibacterium freudenreichii, and enzymes), or forage treated with a buffered propionic acid-based additive (0.2% of fresh weight). Sixty-nine d after ensiling, silages treated with L. buchneri and enzymes had lower pH, but had higher concentrations of acetic and propionic acids and higher concentrations of ethanol when compared with untreated silage. Silage treated with the multistrain inoculant containing L. plantarum had lower pH and higher concentrations of lactic acid, but lower concentrations of ammonia-N, neutral detergent fiber, and acid detergent fiber than did untreated silage. The addition of the buffered propionic acid additive resulted in silage with higher concentrations of lactic and acetic acid compared with untreated silage. Numbers of yeasts in all silages were low at silo opening (less than 3.0 log cfu/g) and were numerically the lowest in silages treated with L. buchneri but only treatment with the intermediate and high level of L. buchneri improved the aerobic stability of silage. Because of the altered fermentation pattern, inoculation with L. buchneri, when applied at equal to or more than 5 x 10(5) cfu/g, and enzymes improved the aerobic stability of barley silage.

We studied the effects of ammonia treatment on microbial populations during the fermentation of corn silage. We also compared the effects of ammonia to a preservative containing buffered propionic acid and other antifungal compounds on the fermentation and aerobic stability of corn silage. In the first experiment, whole-plant corn was ensiled without treatment or treated with ammonia-N to supply an additional 0.3% N (fresh-forage basis). The addition of ammonia immediately increased silage pH and had no effect on numbers of lactic acid bacteria, but delayed their growth compared with untreated silage. Numbers of enterobacteria declined more slowly, but numbers of yeasts and molds declined more quickly in silage treated with ammonia. During the early stages of ensiling, lactic acid increased more rapidly in untreated than in treated silage. The reverse was true for acetic acid concentrations. When exposed to air, growth of yeasts and molds was delayed in ammonia-treated silage. In a second experiment, various levels (0.1 to 0.3%, fresh weight) of ammonium-N or a preservative with buffered propionic acid were added to whole-plant corn and allowed to ensile for 106 d. Silage treated with ammonia had a greater ratio of L- to D-lactic acid than did other silages. Untreated silage was aerobically stable for 32.3 h, whereas the low (42 h) and moderate (52.7 h) concentrations of both additives numerically improved aerobic stability. High concentrations of ammonia-N (0.3%) or a buffered propionic acid preservative (0.3%), markedly improved the aerobic stability of corn silage (82 and 69 h for ammonia and propionic acid-treated silage, respectively).

BackgroundHookworms infect 730 million people in developing countries where they are a leading cause of intestinal blood loss and iron-deficiency anemia. At the site of attachment to the host, adult hookworms ingest blood and lyse the erythrocytes to release hemoglobin. The parasites subsequently digest hemoglobin in their intestines using a cascade of proteolysis that begins with the Ancylostoma caninum aspartic protease 1, APR-1.Methods and FindingsWe show that vaccination of dogs with recombinant Ac-APR-1 induced antibody and cellular responses and resulted in significantly reduced hookworm burdens (p = 0.056) and fecal egg counts (p = 0.018) in vaccinated dogs compared to control dogs after challenge with infective larvae of A. caninum. Most importantly, vaccinated dogs were protected against blood loss (p = 0.049) and most did not develop anemia, the major pathologic sequela of hookworm disease. IgG from vaccinated animals decreased the catalytic activity of the recombinant enzyme in vitro and the antibody bound in situ to the intestines of worms recovered from vaccinated dogs, implying that the vaccine interferes with the parasite's ability to digest blood.ConclusionTo the best of our knowledge, this is the first report of a recombinant vaccine from a hematophagous parasite that significantly reduces both parasite load and blood loss, and it supports the development of APR-1 as a human hookworm vaccine.

For 3 successive yr, whole-plant corn was ensiled in laboratory silos with low percentages of silage preservatives, the primary active ingredient of which was propionic acid. Preservatives were added to forage just prior to ensiling at rates of 0.1 to 0.2% of the fresh forage weight. In all 3 yr, treatments had minor effects on fermentation end products, except that the concentration of propionic acid was greater because of its addition. The mean low and high percentages of preservatives increased aerobic stability of the treated silages by 19 and 57 h, respectively, in Experiment 1 and by 17 and 38 h, respectively, in Experiment 2. In Experiment 3, aerobic stability was improved by > 90 h by preservatives (0.2% addition). In a lactation study, a total mixed ration (46% dry matter) was mixed without or with (0.2 or 0.3%) a stabilizer that was designed to prevent spoilage in the feed bunk. The high dose resulted in orts with a lower pH and temperature after 24 h in the feed bunk. However, dry matter intake and milk production were unaffected by treatments. Chemical preservatives based on propionic acid added at low rates did not affect fermentation but were effective in the reduction of heating in corn silage and in a total mixed ration.