Silage treated with lactic acid bacteria inoculants has been reported to increase ruminal microbial biomass when tested in vitro. Therefore, we tested if alfalfa silage inoculated with Lactobacillus plantarum MTD-1 would improve ruminal N metabolism and increase milk production in high-producing dairy cows. Twenty-eight early lactation Holstein cows (8 ruminally cannulated) were blocked by DIM and milk production; animals were used in a double crossover design consisting of four 28-d periods. Animals in each block were randomly assigned to 2 treatments: a diet containing uninoculated alfalfa silage (control) and a diet containing alfalfa silage inoculated with L. plantarum MTD-1 (LP). Diets were formulated to contain 50% of alfalfa silage, 16% crude protein, and 25% neutral detergent fiber (dry matter basis). Milk production and dry matter intake were recorded in the last 14 d of each period. Milk samples were collected twice at both daily milkings on d 20, 21, 27, and 28 of each period. On d 22, omasal samples were collected from the cannulated animals over a period of 3 d to quantify ruminal digestibility and nutrient flows. Data were analyzed using mixed models of SAS 9.4 (SAS Institute). Compared to the control, cows receiving the LP treatment had greater milk production (40.4 vs. 39.6 kg/d) and lower milk urea nitrogen concentration (11.6 vs. 12.7 mg/dL), despite minor changes in energy-corrected milk. Milk lactose concentration was greater in the milk produced by cows fed the LP treatment, which reflected a tendency for increased milk lactose yield. Although milk true protein concentration was lower for cows in the LP treatment, milk true protein yield was the same on both control and LP treatments. Improvements in milk production of animals under the LP treatment were associated with greater organic matter truly digested in the rumen, especially ruminal neutral detergent fiber digestion. Minor changes were observed in total omasal microbial nonammonia N flow in cows receiving the LP treatment. Therefore, alfalfa silage treated with L. plantarum MTD-1 may improve ruminal fermentation and milk production; however, because of a lack of response in ruminal N metabolism, these changes did not result in greater energy-corrected milk in high-producing dairy cows.

Challenges to ensiling are coming from a wide spectrum. Faster harvest rates are making it more difficult to achieve target silage densities. Larger harvest equipment is increasing soil compaction and rural road issues. Older silos are too small and are overfilled, creating safety issues, or temporary piles are placed on bare ground permitting soil contamination. Mycotoxins and other pathogens in silages are still a problem. Global warming may affect the forage crops grown and crop characteristics as well as rates of silage fermentation and aerobic deterioration. Silage as an input to bio-refineries has an unclear future. Silage analysis is challenged by sampling and knowing what components truly predict nutritional value. The future holds many opportunities for both ensiling and silage research. Robotic harvesting will release more labour for silo packing, and there are opportunities to develop tools to estimate silage density during filling. Total mixed ration silages should allow more by-products in rations. The development of novel silage additives to improve silage hygiene or increase nutrient availability appears promising. Predicting the onset of aerobic deterioration with quick tests for lactate-assimilating yeasts or silage temperatures seems possible. Metabolomics and metabonomics, in addition to the microbiome tools in development, put us at the cusp of being able to see which microorganisms are active in the silo and rumen and what compounds of significance they are producing. This could lead to many advances in silage quality including reduced microbial toxins, better hygiene and improved utilization by livestock.

An overview was made of dry matter (DM) and quality losses that occur during the ensiling process from the field through the feeding phase. The aim was to review the relevant published literature of the last 15 yr focusing on developments achieved after the publication of the book Silage Science and Technology. This review discusses the factors affecting DM and quality losses in terms of field and pre-ensiling conditions, respiration and temperature at ensiling, fermentation patterns, methods of covering and weighting the silage cover, and management of aerobic deterioration. The possibility of reducing DM and quality losses during the ensiling process requires knowledge of how to measure losses on farm and establish the status of the silage during the feed-out phase, implementing the most effective management practices to avoid air exposure during conservation and reduce silage aerobic deterioration during feeding. The paper concludes with future perspectives and recommended management practices to reduce losses and increase efficiency over the whole ensiling process in view of increasing sustainability of the livestock production chain.

Additives have been available for enhancing silage preservation for decades. This review covers research studies published since 2000 that have investigated the efficacy of silage additives. The review has been divided into 6 categories of additives: homofermentative lactic acid bacteria (LAB), obligate heterofermentative LAB, combination inoculants containing obligate heterofermentative LAB plus homofermentative LAB, other inoculants, chemicals, and enzymes. The homofermentative LAB rapidly decrease pH and increase lactic acid relative to other fermentation products, although a meta-analysis indicated no reduction in pH in corn, sorghum, and sugarcane silages relative to untreated silages. These additives resulted in higher milk production according to the meta-analysis by mechanisms that are still unclear. Lactobacillus buchneri is the dominant species used in obligate heterofermentative LAB silage additives. It slowly converts lactic acid to acetic acid and 1,2-propanediol during silo storage, improving aerobic stability while having no effect on animal productivity. Current research is focused on finding other species in the Lb. buchneri group capable of producing more rapid improvements in aerobic stability. Combination inoculants aim to provide the aerobic stability benefits of Lb. buchneri with the silage fermentation efficiency and animal productivity benefits of homofermentative LAB. Research indicates that these products are improving aerobic stability, but feeding studies are not yet sufficient to make conclusions about effects on animal performance. Novel non-LAB species have been studied as potential silage inoculants. Streptococcus bovis is a potential starter species within a homofermentative LAB inoculant. Propionibacterium and Bacillus species offer improved aerobic stability in some cases. Some yeast research has focused on inhibiting molds and other detrimental silage microorganisms, whereas other yeast research suggests that it may be possible to apply a direct-fed microbial strain at ensiling, have it survive ensiling, and multiply during feed out. Chemical additives traditionally have fallen in 2 groups. Formic acid causes direct acidification, suppressing clostridia and other undesired bacteria and improving protein preservation during ensiling. On the other hand, sorbic, benzoic, propionic, and acetic acids improve silage aerobic stability at feed out through direct inhibition of yeasts and molds. Current research has focused on various combinations of these chemicals to improve both aerobic stability and animal productivity. Enzyme additives have been added to forage primarily to breakdown plant cell walls at ensiling to improve silage fermentation by providing sugars for the LAB and to enhance the nutritive value of silage by increasing the digestibility of cell walls. Cellulase or hemicellulase mixtures have been more successful at the former than the latter. A new approach focused on Lb. buchneri producing ferulic acid esterase has also had mixed success in improving the efficiency of silage digestion. Another new enzyme approach is the application of proteases to corn silage to improve starch digestibility, but more research is needed to determine the feasibility. Future silage additives are expected to directly inhibit clostridia and other detrimental microorganisms, mitigate high mycotoxin levels on harvested forages during ensiling, enhance aerobic stability, improve cell wall digestibility, increase the efficiency of utilization of silage nitrogen by cattle, and increase the availability of starch to cattle.

Dairy slurry is used commonly as an animal-sourced fertilizer in agronomic production. However, residual effects of slurry application on intake and digestibility of alfalfa (Medicago sativa L.) silage from subsequent harvests are not well known. The objective of this study was to determine if moisture concentration of alfalfa silage and timing of dairy slurry application relative to subsequent harvest affected intake and digestibility by sheep. Katahdin crossbred ewes (n = 18; 48 ± 5.3 kg) in mid-gestation were stratified by BW and allocated randomly in each of two periods to one of six treatments arranged in a two × three factorial arrangement. Treatments consisted of recommended (RM; 46.8%) or low (LM; 39.7%) moisture at baling after either no slurry application (NS), slurry application to stubble immediately after removal of the previous cutting (S0), or slurry application 14 d after removal of the previous cutting (S14). Silages were chopped through a commercial straw chopper, packed into plastic trash cans, and then offered to ewes within 4 d of chopping. Period 1 of the intake and digestion study consisted of a 14-d adaptation followed by a 7-d fecal collection period. Period 2 followed period 1 after a 4-d rest and consisted of an 11-d adaptation followed by 7 d of fecal collection. Ewes were housed individually in 1.4 × 4.3-m pens equipped with rubber mat flooring. Feces were swept from the floor twice daily, weighed, and dried at 50 °C. Ewes had ad libitum access to water and were offered chopped silage for a minimum of 10% refusal (DM). Blood samples were collected immediately prior to feeding, and 4 and 8 h after feeding on the day prior to the end of each period. Organic matter intake (g/kg BW) and OM digestibility tended (P < 0.10) to be, and digestible OM intake (g/kg BW) was reduced by slurry application. Lymphocytes (% of total white blood cells) were greater (P < 0.05) from LM vs. RM and from NS vs. S0 and S14. Red blood cell concentrations were greater (P < 0.05) from S14 vs. S0 and from S0 and S14 vs. NS. Serum urea N concentrations did not differ (P > 0.17) across treatments. Therefore, moisture concentration of alfalfa silage within the range used in this study may not affect voluntary intake or digestibility, but slurry application may have an effect on digestible OM intake. Also, moisture concentration of alfalfa silage and time of dairy slurry application may affect specific blood hemograms.

Neonatal calves are characterized by high morbidity and mortality rates, in part due to insufficient organ development (as of the gastrointestinal tract, GIT) and functioning of controlling systems. Time-point and amounts of ingested colostrum influence GTI development and function, and nutritional, immune, metabolic and endocrine status. Optimal amounts of ingested colostrum are not well defined, but ad libitum availability is expectedly best, such as when calves suckle their dam. Colostrum contains high amounts of nutritional and non-nutritional (bioactive) components. For several of the ingested colostral hormones and growth factors (insulin; insulin-like growth factors, IGFs) the GIT contains specific receptors that are affected by nutrition and exhibit ontogenetic changes. Supplementation of non-nutritional colostrum extracts (with high amounts of IGFs, insulin, lactoferrin and other growth factors), but not IGF-I alone, can slightly stimulate small intestinal development. The sum of all colostral components exerts optimal effects, but some factors are special importance.

Two lactation trials were conducted comparing the feeding value of silages made from birdsfoot trefoil (BFT, Lotus corniculatus L.) that had been selected for low (BFTL), medium (BFTM), and high (BFTH) levels of condensed tannins (CT) to an alfalfa silage (AS) when fed as the principal forage in total mixed rations. Diets also included corn silage, high-moisture shelled corn, soybean meal, soy hulls, and supplemental fat. In trial 1, 32 lactating Holstein cows were blocked by days in milk, assigned to treatment sequences in 8 balanced 4 × 4 Latin squares, and fed 50% dietary dry matter from AS or 1 of 3 BFT silages containing 0.6, 1.2, or 1.7% CT. Diets averaged 17.5 to 19.5% crude protein and 26% neutral detergent fiber on a dry matter basis. Data were collected over the last 2 wk of each 4-wk period. Intakes were 1.3 to 2.8 kg of dry matter/d greater on BFT than on AS and cows gained 0.5 kg of body weight/d on BFT diets while losing 0.14 kg of body weight/d on the AS diet; this resulted in greater milk per dry matter intake (DMI) on AS. Linear effects indicated true protein yield and milk urea nitrogen declined with increasing CT concentration and quadratic effects indicated DMI, energy-corrected milk, and fat yield were increased at intermediate CT concentration. True protein yield and apparent N-efficiency were greater, and milk urea nitrogen lower, on all BFT diets than on AS. In trial 2, 50 lactating Holstein cows were fed a covariate AS diet for 2 wk and then blocked by parity and days in milk and randomly assigned to 1 of 5 diets that were fed continuously for 12 wk. Diets contained (dry matter basis) 48% AS, 16% AS plus 32% of 1 of 3 BFT silages with 0.5, 0.8, or 1.5% CT, or 48% of an equal mixture of each BFT silage. Diets averaged 16.5% crude protein and 30% neutral detergent fiber. Intake and milk yield tended to be lower on AS than BFT, but body weight gains averaged 0.6 kg/d on all diets. Cows fed any of the BFT silages had reduced milk urea nitrogen and ruminal ammonia and reduced urinary N excretion. Feeding the BFT mixture reduced concentrations of milk true protein and milk urea nitrogen and depressed apparent nutrient digestibility. Among diets containing the individual BFT silages, linear reductions in DMI and yield of milk, fat, true protein, lactose, and SNF were observed with increasing CT concentration. By contrast, a previous trial with the same BFT populations showed that substituting BFTH silage containing 1.6% CT for AS in rations containing 60% silage dry matter had no effect on intake, increased yield of milk, energy-corrected milk and milk components, elevated protein use-efficiency, but with a more modest reduction in milk urea nitrogen and urinary N excretion. Silage analyses suggested that the inconsistent responses among trials were related to growth environment or ensiling effects that altered tannin-protein interactions in BFT silage. Differences in diet formulation among trials may have also influenced responses. Results from the current and previous trials indicate further work is needed to identify optimum tannin levels in forages.

Aims: To assess the effect of two additives on alfalfa silage and on in vitro ruminal fermentation when using ruminal inocula from high feed-efficient (HE) and low feed-efficient (LE) lactating cows.Methods and Results: First-and second-cut alfalfa was harvested at 40% bloom stage, treated with control (no additive), Lactobacillus plantarum (LP) or formic acid (Formic), ensiled in 1 +/- 0 l minisilos, and fermented for 60 days. Fermented alfalfa was incubated in vitro for 24 h using ruminal inoculum from HE and LE lactating cows. The pH was lower in alfalfa silage treated with LP and Formic, and produced lower ammonia-N than did the control. In vitro true dry matter digestibility (IVTDMD) was higher with ruminal inoculum from HE than LE cows, but there was no consistent effect of treated alfalfa on microbial biomass yield and in vitro volatile fatty acids.Conclusions: The IVTDMD was numerically greater with ruminal inoculum from higher feed-efficient cows although statistical significance was only demonstrated with the first-cut alfalfa. However, treated alfalfa silage did not show the effect expected on in vitro microbial biomass yield.Significance and Impact of the Study: The feed efficiency of cows used as a source of ruminal inocula may affect IVTDMD and be a source of variation across in vitro runs. Differences in ruminal fermentation between cows of different feed efficiency could help to explain differences in milk yield and other parameters of dairy cattle performance.

Silages made from birdsfoot trefoil (BFT) containing 3 levels of condensed tannins (CT) were compared with alfalfa silage (AS) as the principal forage in the diets of lactating dairy cows. Thirty-five multiparous and 15 primiparous Holstein cows were fed a covariate diet for 2 wk and then blocked by parity and DIM and randomly assigned to 1 of 5 diets in a trial of randomized complete block design. Experimental diets were fed as total mixed ration for 12 wk and contained 48% (DM basis) AS or 16% AS plus 32% BFT with low CT (BFTL), normal CT (BFTN), or high CT (BFTH) or a mixture with equal DM from all 3 BFT silages. The BFTL, BFTN, and BFTH contained 5.1, 8.4, and 14.8 g CT/kg DM, respectively. The balance of dietary DM was fed as corn silage, high-moisture shelled corn, soybean meal, soy hulls, Energy Booster®, and macro- and trace minerals plus vitamins A, D, and E. Diets were formulated to 16.5% CP and 30% NDF. Statistical analyses were performed using the mixed procedures of SAS; results are in Table 0630. Intake and yield of milk, ECM, true protein, lactose, and SNF were greater on BFTL and BFTN than on AS and BFTH, whereas the BFT mix was intermediate. Apparent N efficiency also was numerically higher on BFTL and BFTN than on the other 3 diets; MUN was lower on all BFT diets than on AS. These results suggest that CT concentrations of approximately 5 to 8 g/kg DM in BFT improve utilization of forage nutrients for milk production.

Two experiments were conducted to evaluate the effects of ensiling time and microbial inoculation on N fractions and starch digestibility in either well-processed corn shredlage (SHRD; Exp. 1; 76% of starch passing through a 4.75-mm screen, 39.3% DM, and 32.2% amylase-treated NDF) or late-maturity corn silage (Exp. 2; 48.0% DM and 22.9% amylase-treated NDF). For Exp. 1, unfermented SHRD was allocated into 24 samples of 600 g each and randomly assigned to 6 treatments in quadruplicate. Treatments were a combination of SHRD noninoculated (CON) or inoculated at the recommended inoculation rate (1X; 5 × 104 cfu of Lactobacillus plantarum, Lactobacillus casei, Streptococcus faecium, and Pediococcus per gram of fresh whole-plant corn) or twice the recommended inoculation rate (2X; 10 × 104 cfu/g of fresh whole-plant corn) of a microbial inoculant and ensiled for 30 or 120 d. Exp. 2 used the same experimental methodology except for evaluating treatments within late-maturity corn silage rather than SHRD. In Exp. 1, DM and starch concentrations were unaffected by treatments. Although not affected by inoculation, content of CP increased from 30 to 120 d of ensiling. Measurements of pH were reduced from 3.96 at 30 d to 3.88 after 120 d. Concentrations of lactate and ethanol were similar but acetate and total acids were greater after 120 d. Ammonia-N concentration and starch digestibility increased from 30 to 120 d. Fermentation profile, including ammonia-N, and starch digestibility of SHRD were unaffected by inoculation. In Exp. 2, ensiling time did not affect concentrations of DM, CP, and starch. However, DM and starch contents were 2.5 and 3.4 percentage units greater for 2X than other treatments. Concentrations of lactate and total acids were greater for CON and 1X than 2X. Propionate and ethanol concentrations tended to be greater for CON than other treatments. Despite the lower ammonia-N concentration for 2X, starch digestibility was unaffected by microbial inoculation. Greater lactate, acetate, and total acid concentrations after 120 d of ensiling were observed. Reductions in pH and ethanol concentration were also observed for 120 d compared with 30 d. Late-maturity corn silage fermented for 120 d had greater ammonia-N (5.4 vs. 4.0% of CP) and starch digestibility (66.7 vs. 61.7% of starch) compared with 30 d. Ammonia-N concentration and starch digestibility were greater after 120 d of fermentation in both experiments, suggesting that extended ensiling time is advantageous in both scenarios. Inoculation with lactate-producing bacteria, however, did not improve starch digestibility in either experiment.

The primary goal in harvesting and ensiling a crop is to preserve as nearly as possible the quantity and quality of the crop at the time of cutting. Depending on climate, forages may be mown, laid on the stubble in a swath, and then allowed to wilt in the field prior to chopping and ensiling. Most forages that are wilted are cut with a mower-conditioner. The mowing operation is most frequently done via a reciprocating cutterbar or a rotary disk. Plant respiration causes the most significant physiological or metabolic loss during the wilting process, and some respiration loss is unavoidable. Proteolysis is the other major plant enzyme activity occurring during wilting. Proteases in the plant hydrolyze plant proteins into peptides, free amino acids, and amides. Rainfall during wilting has a variety of effects on a crop and its subsequent ensilability.

In many parts of the world, conserved forage is an essential component of ruminant diets during those intervals when fresh crops are unavailable. A. J. G. Barnett subdivided the process of ensiling into four principal phases of different length and intensity, which cannot be separated precisely from each other. When silage is used as a feed source on a farm, several events take place that have relevance to the number of clostridial spores in silage and milk. During mowing and harvesting of a silage crop, contamination of the crop by soil particles, which contain clostridial spores, is unavoidable. The microbial population of standing or freshly harvested forage crops is considerably different from that found during the process of silage fermentation or in the final product. Most inoculants consist exclusively of homofermentative or facultatively heterofermentative lactic acid bacteria because these are the most efficient producers of lactic acid.

The effects of below-freezing temperatures on silage fermentation are poorly understood. Recently, several studies have evaluated the efficacy of producing fall-grown oat (Avena sativa L.) as an emergency silage crop within central Wisconsin; this late-season forage option is attractive because the yield potential is good, and these forages also may accumulate significant amounts of sugar following frost events. 'Vista' oat from two field sites was harvested at the boot (Experiment 1) or early-heading (Experiment 2) stages of growth, and then baled and ensiled in plastic film on 15 Nov. 2013. Bales were sampled over the winter and spring, concluding with a final sampling date of 15 May. Generally, there was little evidence of silage fermentation before internal bale temperatures exceeding 32 degrees F, which occurred on 15 and 13 April for Experiments 1 and 2, respectively. During the final month of sampling, the respective pH of these silages declined to 4.61 and 5.71 for Experiments 1 and 2, and substantial amounts of ethanol were produced in each case (5.82 and 4.85%); however, lactic acid production was much greater for Experiment 1 (4.82%) than for Experiment 2 (1.63%). Silage fermentation within both experiments likely included significant activity by anaerobic yeasts, which metabolize sugars, thereby yielding ethanol and CO2. These results indicate that silage fermentation can be delayed until spring by below-freezing temperatures within the ensiled forage mass, and the high sugar content of these oat forages (>= 21.0%) can encourage the production of ethanol, likely through activity of anaerobic yeasts.