L. Kung

The effects of Lactobacillus buchneri with or without a homolactic bacterium on the fermentation and aerobic stability of corn silages made at different locations

Whole-plant corn (31 to 39% dry matter) from several locations was chopped, treated with nothing (U), Lactobacillus buchneri 40788 (4 x 10(5) cfu/g; LB), or L. buchneri (4 x 10(5) cfu/g) and Pediococcus pentosaceus (1 x 10(5) cfu/g; LBPP), and packed into quadruplicate 20-L silos to determine their effects on silage fermentation and aerobic stability after 120 d of storage. The experiment was a randomized complete block design with main effects of treatment (T), block (location; L), and T x L interaction. Dry matter recovery was different among locations but unaffected by T. The population of lactic acid bacteria was greater in LB and LBPP than in U, and the opposite was true regarding the population of yeasts. Numbers of L. buchneri (colony-forming unit equivalents), determined by a real-time quantitative polymerase chain reaction, were higher in 4 of 5 locations for LB and LBPP compared with U (T x L interaction) with an average 6.70 log cfu/g for LB and LBPP versus 4.87 log cfu/g for U. Silages inoculated with LB and LBPP had higher silage pH and higher concentrations of acetic acid and 1,2 propanediol but lower concentrations of ethanol and water-soluble carbohydrates; there was a T x L interaction for all these variables. Aerobic stability was improved by LB and LBPP (mean of 136 h) compared with U (44 h), but there was an interaction between T x L. In general, locations with the highest population of L. buchneri had the largest increases in acetic acid and, consequently, the greatest improvements in aerobic stability. The addition of L. buchneri 40788 alone or with P. pentosaceus resulted in similar effects on silage fermentation and aerobic stability, but the effects were variable among locations, suggesting that unidentified factors; for example, in the field or on the forage crop, may alter the effectiveness of microbial inoculation.

A Blend of Essential Plant Oils Used as an Additive to Alter Silage Fermentation or Used as a Feed Additive for Lactating Dairy Cows

A blend of essential plant oils was evaluated for its effects on silage fermentation and animal performance. In the first experiment, the blend of essential oils was mixed with freshly chopped whole-plant corn to achieve a concentration of 0, 40, or 80 mg of active product per kilogram of fresh forage weight. Whole-plant corn was also mixed with a buffered propionic acid-based product at 0.2% of fresh forage weight. The blend of essential oils did not affect the populations of yeasts, molds, lactic acid bacteria, or enterobacteria; the fermentation end products; or the aerobic stability of the corn silage. Addition of the buffered propionic acid additive moderately reduced the production of acids during fermentation and resulted in a small reduction in the numbers of yeasts after ensiling, but did not affect aerobic stability. In a second experiment, 30 Holstein cows (4 primiparous and 26 multiparous) averaging 118 +/- 70 d in milk and producing 38 +/- 16 kg of milk/d were fed a total mixed ration, once daily, that consisted of (on a DM basis) 25% corn silage, 15% alfalfa silage, 10% alfalfa hay, and 50% concentrate. One-half of the cows were fed a blend of essential oils that was mixed directly into their total mixed ration to provide 1.2 g/cow per d for 9 wk. Cows fed the essential oils ate 1.9 kg more dry matter/d and produced 2.7 kg more 3.5% fat-corrected milk/d than did cows fed the control diet. The percentages of milk fat and protein, the somatic cell count numbers, and the concentrations of milk urea nitrogen were unaffected by treatment. Feed efficiency, change in body weight, and change in body condition scoring were also similar between treatments. After 12 h of incubation, the addition of a moderate dose and a high dose of essential oils to in vitro ruminal fermentations had no effect on the concentration of total VFA compared with the control treatment. However, they decreased the molar proportions of acetic, butyric, and valeric acids and increased the proportion of propionic acid. The blend of essential oils evaluated in this study altered in vitro ruminal fermentation and improved animal performance when fed directly to cows, but it did not affect the fermentation or aerobic stability of corn silage.

The Effect of Silage Cutting Height on the Nutritive Value of a Normal Corn Silage Hybrid Compared with Brown Midrib Corn Silage Fed to Lactating Cows

A brown midrib (BMR) hybrid and a silage-specific non-BMR (7511FQ) hybrid were harvested at a normal cut height leaving 10 to 15 cm of stalk in the field. The non-BMR hybrid was also cut at a greater height leaving 45 to 50 cm of stalk. Cutting high increased the concentrations of dry matter (+4%), crude protein (+5%), net energy for lactation (+3%), and starch (+7%), but decreased the concentrations of acid detergent fiber (-9%), neutral detergent fiber (-8%), and acid detergent lignin (-13%) for 7511FQ. As expected, the BMR corn silage was 30% lower in lignin concentration than 7511FQ. After 30 h of in vitro ruminal fermentation, the digestibility of neutral detergent fiber for normal cut 7511FQ, the same hybrid cut high, and the normal cut BMR hybrid were 51.7, 51.4, and 63.5%, respectively. Twenty-seven multiparous lactating cows were fed a total mixed ration composed of the respective silages (45% of dry matter) with alfalfa haylage (5%), alfalfa hay (5%), and concentrate (45%) (to make the TMR isocaloric and isonitrogenous) in a study with a 3 x 3 Latin square design with 21-d periods. Milk production was greater for cows fed the BMR hybrid (48.8 kg/d) compared with those fed the normal cut 7511FQ (46.8 kg/d) or cut high (47.7 kg/d). Dry matter intake was not affected by treatment. Feed efficiency for cows fed the BMR silage (1.83) was greater than for those fed high-cut 7511FQ (1.75), but was not different from cows fed the normal cut 7511FQ (1.77). Cows fed the BMR silage had milk with greater concentrations of lactose but lower milk urea nitrogen than cows on other treatments. Harvesting a silage-specific, non-BMR corn hybrid at a high harvest height improved its nutritive content, but the improvement in feeding value was not equivalent to that found when cows were fed BMR corn silage.

The effects of hybrid, maturity, and length of storage on the composition and nutritive value of corn silage

The objective of this study was to evaluate the effect of hybrid, maturity at harvest [dry matter (DM) content], and length of storage on the composition and nutritive value of corn silage. The plants used in this study included a normal (NORM) and a brown midrib (BMR) hybrid, harvested at 32 or 41% DM and ensiled for various lengths of time (0 to 360 d) without inoculation. Measurements included nutrient analysis, fermentation end products, in vitro digestion of NDF (NDF-D, 30 h), and in vitro digestion of starch (7h). The concentration of acetic acid increased with length of storage for all treatments, specifically increasing as much as 140% between d 45 to 360 for 32% DM BMR silage. Small changes in lactic acid and ethanol were noted but varied by DM and hybrid. When averaged across maturities and length of storage, compared with NORM, BMR silage was lower in concentrations of lignin, crude protein, neutral detergent fiber, and acid detergent fiber, but higher in starch. On average, NDF-D of both hybrids was not affected by length of storage between 45 and 270 d. The NDF-D was markedly greater for BMR than NORM after all times of storage. Increasing maturity at harvest generally did not affect the NDF-D of NORM, with the exception that it was slightly lower for the more mature plants at 270 and 360 d. In contrast, the NDF-D of BMR was lower in more mature silage by approximately 5 percentage units from 45 to 360 d. The concentration of starch for 32% DM NORM was lower (21%) than other treatments (31±3%; mean±SD) at harvest. This finding was probably the cause for starch digestibility to be highest in 32% DM NORM samples atd 0 (about 80%) and lower (65 to 68%) for other treatments. Concentrations of soluble N and ammonia-N increased with length of storage, indicating that proteolytic mechanisms were active beyond 2 to 3 mo of storage. The in vitro digestion of starch generally increased with length of storage, probably as a result of proteolysis. Although active fermentation occurs for only a relatively short time in the silo, many metabolic processes remain active during long-term storage. Changes in the nutritive value of corn silage during storage should be accounted for during ration formulations.

Short communication: An evaluation of the effectiveness of Lactobacillus buchneri 40788 to alter fermentation and improve the aerobic stability of corn silage in farm silos

The objective of this study was to determine if the effects of inoculation with Lactobacillus buchneri 40788 were detectable when applied to whole-plant corn stored in farm silos. Corn silage was randomly sampled from farms in Wisconsin, Minnesota, and Pennsylvania, and was untreated (n = 15) or treated with an inoculant (n = 16) containing L. buchneri 40788 alone or this organism combined with Pediococcus pentosaceus during May and June 2007. Corn silage that was removed from the silo face during the morning feeding was sampled, vacuum-packed, and heat sealed in polyethylene bags and shipped immediately to the University of Delaware for analyses. Silage samples were analyzed for dry matter (DM), nutrient composition, fermentation end-products, aerobic stability, and microbial populations. The population of L. buchneri in silages was determined using a real-time quantitative PCR method. Aerobic stability was measured as the time after exposure to air that it took for a 2 degrees C increase above an ambient temperature. The DM and concentrations of lactic and acetic acids were 35.6 and 34.5, 4.17 and 4.85, and 2.24 and 2.41%, respectively, for untreated and inoculated silages and were not different between treatments. The concentration of 1,2-propanediol was greater in inoculated silages (1.26 vs. 0.29%). Numbers of lactic acid bacteria determined on selective agar were not different between treatments. However, the numbers of L. buchneri based on measurements using real-time quantitative PCR analysis were greater and averaged 6.46 log cfu-equivalents/g compared with 4.89 log cfu-equivalent for inoculated silages. There were fewer yeasts and aerobic stability was greater in inoculated silages (4.75 log cfu/g and 74 h of stability) than in untreated silages (5.55 log cfu/g and 46 h of stability). This study supports the effectiveness of L. buchneri 40788 on dairy farms.

An evaluation of exogenous enzymes with amylolytic activity for dairy 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.

Effect of physical damage to ears of corn before harvest and treatment with various additives on the concentration of mycotoxins, silage fermentation, and aerobic stability of corn silage.

We studied the effects of damaging ears of corn in the field prior to harvest and the use of various additives on the production of selected mycotoxins, silage fermentation, and aerobic stability of whole plant corn. In experiment 1, ears of corn were undamaged or were slashed with a knife 7 d before harvesting, exposing damaged kernels to the environment. Corn plants were harvested (about 35% DM) and treated in a 2 × 2 factorial arrangement of treatments. Treatments were undamaged or damaged plants, untreated or treated with Lactobacillus buchneri 40788 (400,000 cfu/g of fresh forage) and Pediococcus pentosaceus (100,000 cfu/g). Damaging ears prior to harvest increased the amount of fumonisin but decreased the amount of starch in harvested corn plants. After ensiling, corn silage made from plants damaged before harvest had lower starch but greater concentrations of deoxynivalenol and fumonisin than silage made from plants that were undamaged. Microbial inoculation resulted in fewer yeasts and lower concentrations of zearalenone in silage when compared to uninoculated silage. Inoculated silage also had more acetic acid and 1,2-propanediol than did uninoculated silage. In experiment 2, ears of corn were undamaged or were slashed with a knife 27 d or 9 d before harvesting for corn silage. Whole plants were harvested at about 36% DM in a 2 × 3 factorial arrangement of treatments. Factors were time of damaging the ears (27 d, 9 d, or no damage) relative to harvest and no additive or 0.1% (fresh weight) potassium sorbate. Damaging plants 9 d prior to harvest did not affect the concentrations of deoxynivalenol, fumonisin, and zearalenone in plants at harvest. However, concentrations of deoxynivalenol and fumonisin were increased in fresh forage that had ears damaged at 27 d when compared to corn plants that were undamaged. Corn plants damaged for 27 d prior to harvest also had a lower concentration of starch than corn damaged for 9 d but was higher in acid detergent fiber than other treatments. The addition of potassium sorbate at harvest had no effect on the concentrations of mycotoxins in the resulting silage, but concentrations of mycotoxins were still greatest in silage made from plants that were damaged the longest prior to harvest (27 d). Silages treated with potassium sorbate had fewer yeasts and molds than silages without the additive. Damaging ears of corn before harvest had no effects on the aerobic stability of silages in both experiments. In contrast, the addition of the inoculant and potassium sorbate improved aerobic stabilities of silages when compared to untreated silages. These studies showed that physical damage to ears of corn prior to harvest can result in the production of mycotoxins in the field. This finding suggests that producers should test corn silage for mycotoxins prior to feeding especially if the forage has been subjected to physical damage prior to ensiling.

Effects of various compounds on in vitro ruminal fermentation and production of sulfide.

We evaluated the effect of several compounds on their ability to reduce the production of sulfide in in vitro ruminal fermentations, when sulfur content of the diet was 1% (dry matter basis). Excess sulfur increased (p 50% when cultures were treated with monensin. Interactions between methanogens and sulfate-reducing organisms may be responsible for this finding. Several compounds have the ability to reduce ruminal sulfide production without negative effects on ruminal fermentation.

Effect of a microbial inoculant (Ecosyl™ and/or a glycopeptide antibiotic (vancomycin) on fermentation and aerobic stability of wilted alfalfa silage

First cutting alfalfa was wilted (420 g dry matter kg−1) and was untreated (control) or treated with a microbial inoculant (Ecosyl™, Lactobacillus plantarum), a glycopeptide antibiotic (vancomycin, 50 or 150 ppm), or combinations of inoculant and antibiotic before ensiling. Microbial inoculation increased initial counts of lactic acid bacteria from approximately 3.5 to 4.9 log10 cfu g−1 forage. Inoculation markedly improved fermentation as evident by lower silage pH (P < 0.01), acetic acid (P < 0.05) and NH3-N (P < 0.05) contents and greater amounts of lactic acid after 56 days of ensiling. Inoculation also caused a rapid decrease in coliform bacteria and yeasts and molds. Treatment with vancomycin resulted in an immediate decrease in coliform bacteria and a tendency for lower yeast and molds throughout ensiling. Antibiotic-treated silage also had a lower silage pH (P < 0.01) relative to control silage in the early, but not the later stages of ensiling. Other aspects of fermentation were not consistently improved by vancomycin. Silages treated with both inoculant and antibiotic had fermentations similar to silages treated only with the inoculant. No additive effects of inoculant and antibiotic were detected. The pH of control silage and silage treated only with inoculant was stable up to 4 days of aerobic exposure. However, silage treated with inoculant plus antibiotic had a reduced aerobic stability as pH increased to above pH 6, and total yeasts and molds were more than 6.5 log10 cfu g−1 silage after 4 days of aerobic exposure.

Rumen fermentation and nutrient digestion in cattle fed diets varying in forage and energy source

Abstract Four Holstein steers, each fitted with a rumen fistula and duodenal t-shaped cannula, were used in a 4 × 4 Latin square design to measure the rumen fermentation and digestibility of the following diets: (1) alfalfa hay and barley; (2) alfalfa hay and ground corn; (3) corn silage and barley; (4) corn silage and corn. All diets contained 50% forage and 50% concentrate on a dry matter (DM) basis, with a minimum of 10% of the DM as alfalfa hay. Diets based on alfalfa hay had more organic matter digestion in the rumen and total digestive tract than those containing corn silage. Diets containing corn as the major concentrate energy source had less ruminal starch digestion and a greater flow of organic matter to the duodenum than diets containing barley. Total tract digestion of nitrogen (N) was greater for barley than corn diets, but was similar between forage sources. Neither the forage nor concentrate energy source affected bacterial protein synthesis. Rumen pH was higher and ammonia-N was lower in alfalfa than barley diets. In addition, rumen acetate was higher and rumen propionate was lower, resulting in a greater acetate-to-propionate ratio in alfalfa diets.