Although the concept of ensiling large-round or large-square bales dates back to the late 1970s, many refinements have been made to both equipment and management since that time, resulting in much greater acceptance by small or mid-sized dairy or beef producers. This silage preservation technique is attractive to producers for several reasons, but the primary advantage is a reduced risk of weather damage to valuable forage crops compared with preservation as dry hay. Most core principles for making high-quality precision-chopped silages also apply to baled silages; among these, establishing and subsequently maintaining anaerobiosis are priorities. For baled silages, these priorities are critical, in part because recommended moisture concentrations (45 to 55%) are drier, and particle length is much longer. These factors act to restrict the rate and extent of silage fermentation, often resulting in less production of desirable fermentation acids and a greater (less acidic) final pH. Within this context, preservation of baled silages can be improved by applying polyethylene (PE) film wraps promptly, using an appropriate number of PE film layers (6 to 8), selecting a storage site free of sharp objects or other debris, and by monitoring wrapped bales closely for evidence of puncture, particularly by birds or vermin. Under certain conditions, such as those in which the bale moisture of highly buffered forages exceeds the recommended range, the heterogeneous nature of baled silages coupled with a restricted rate and extent of fermentation may increase susceptibility to clostridial activity compared with precision-chopped forages ensiled at comparable moisture concentrations. To date, research evaluating inoculants or other additives designed to improve the fermentation of challenging forages or aerobic stability has been limited, but should not be discontinued. Development of PE film embedded with an oxygen-limiting barrier has yielded positive results in some trials; however, most differences between these novel formulations and reputable commercial PE film have been related to decreases in yeast and mold counts at the surface layer. Related assessments of fermentation or nutritive value determined on a whole-bale basis have been less conclusive. Baled silages can be produced successfully by adhering to straightforward management principles; as such, this form of silage production is likely to remain popular for the foreseeable future.

The frustrations of forage producers attempting to conserve high-quality alfalfa (Medicago sativa L.) silage during periods of unstable or inclement weather are widely known. Our objectives for this series of studies were to (1) assess indicators of ensilability, such as pH, buffering capacity, water-soluble carbohydrates (WSC), and starch for wilting alfalfa forages receiving no rainfall or damaged by simulated or natural rainfall events; (2) use these data as inputs to calculate the threshold moisture concentration that would prohibit a clostridially dominated fermentation; and (3) further evaluate the effects of rain damage or no rain damage on measures of forage nutritive value. Rainfall events were applied to wilting forages by both simulated and natural methods over multiple studies distributed across 4 independent forage harvests. Generally, simulated rainfall was applied to alfalfa under controlled conditions in which forages were relatively wet at the time of application, and subsequently were dried to final moisture endpoints under near ideal conditions within a constant temperature/humidity environmental chamber, thereby limiting postwetting wilting time to ≤21 h. As a result, indicators of ensilability, as well as measures of nutritive value, changed only marginally as a result of treatment. Consistently, reductions in concentrations of WSC and starch occurred, but changes in WSC were relatively modest, and postwetting concentrations of WSC may have been buoyed by hydrolysis of starch. When forages were subjected to natural rainfall events followed by prolonged exposure under field conditions, indicators of ensilability were much less desirable. In one study in which alfalfa received 49.3mm of natural rainfall over a prolonged (8-d) field-exposure period, fresh pH increased from 6.48 to 7.43 within all forages exposed to these extended, moist wilting conditions. Furthermore, sharp reductions were observed in buffering capacity (410 vs. 337 meq/kg of DM), WSC (6.13 vs. 2.90%), starch (2.28 vs. 0.45%), and clostridially dominated fermentation (62.7 vs. 59.4%). Based on these experiments, the potential for good fermentation is affected only minimally by single rainfall events applied to relatively wet forages, provided these events are followed by rapid dehydration; however, attaining acceptable silage fermentations with forages subjected to prolonged exposure under poor drying conditions is likely to be far more problematic.

The use of triticale (X Triticosecale Wittmack) in dairy-cropping systems has expanded greatly in recent years, partly to improve land stewardship by providing winter ground cover. Our objective was to establish relationships relating indices of nutritive value with growth stage or accumulated growing degree days >5°C for triticale forages grown in central Wisconsin. Replicated 3.7-m × 9.1-m plots were established following removal of corn for silage (fall 2015) and soybeans (fall 2016) and then harvested at various growth stages the following spring. Plants were assigned a numerical growth stage based on a linear staging system suitable for use as an independent regression variable. Response variables [e.g., dry matter (DM) yield, indices of nutritive value, and parameters from in vitro DM disappearance kinetics] were regressed on growth stage and growing degree days using linear, quadratic, cubic, or quartic models. For spring 2016, the mean DM yield at the boot stage (3,804 kg of DM/ha) was only 30% of that observed at the soft dough stage of growth (12,642 kg of DM/ha). Although yields were reduced during spring 2017, primarily due to spring flooding, the relationship between respective yields at these growth stages was similar (1,453 vs. 5,399 kg of DM/ha). Regressions of DM yield (kg/ha) on growth stage for 2016 were explained by a cubic model (Y = 0.0663x3 - 9.44x2 + 595x - 9,810) compared with a simple linear response for 2017 (Y = 103x - 3,024); in both cases, coefficients of determination were very high (R2 ≥ 0.934). Many nutritional and in vitro DM disappearance characteristics were affected by the juxtaposition and balance of 2 generally competing factors: (1) increased concentrations of structural plant fiber coupled with concurrent lignification as plants matured and (2) the accumulation of highly digestible carbohydrate during seed head development. A comparison of respective energy yields between the boot and soft dough stages of growth for 2016 (2,488 vs. 8,141 kg of total digestible nutrients/ha) and 2017 (1,033 vs. 3,520 kg of total digestible nutrients/ha) suggests that yields of energy are greater at soft dough stage and are mostly driven by DM yield. An informed harvest management decision for lactating cows may still favor a boot-stage harvest because of superior nutritional characteristics, a need to plant double-cropped corn expeditiously, or both. Harvest timing of triticale forages for other livestock classes would appear to be more flexible, but prioritizing a subsequent double crop may reduce the effects on DM yield to a secondary consideration.

The objectives were to nutritionally induce or blunt ruminal acidosis in young calves and to compare indicators of rumen and systemic health. Ten bull calves (n = 5/diet) were ruminally cannulated at 3 wk of age and received milk replacer and 1 of 2 calf starter diets that were designed to cause (AC; pelleted, 42.7% starch, 15.1% neutral detergent fiber, 57.8% nonfiber carbohydrates) or blunt (BL; texturized, 35.3% starch, 25.3% neutral detergent fiber, 48.1% nonfiber carbohydrates) ruminal acidosis. Mean birth weight was 38.7 ± 1.3 kg. Body weight and calf starter intake were measured weekly. Rumen contents were sampled at -8, -4, 0, 2, 4, 8, 12, and 24 h relative to starter feeding during wk 6, 8, 10, 12, 14, and 16 of age. Blood was collected from the jugular vein during the same weeks for complete blood cell count, blood pH, and partial pressures of oxygen and carbon dioxide. Rate of starter consumption was assessed during wk 16. Marker systems were used to estimate liquid passage and volatile fatty acid absorption rates. Calves were slaughtered at 17 wk, and rumen tissue was collected and assessed for papillae length, width, and degree of tissue degradation. Mean ruminal pH ± standard error was 5.37 ± 0.24 and 5.63 ± 0.24 for AC and BL calves, respectively. Lowest pH values were observed the week after weaning. Total ruminal volatile fatty acid concentrations were 131.5 and 124.8 ± 2.4 mM in AC and BL calves, respectively, and increased with age and time after feeding. Dry matter intake was lower in AC calves at wk 4 and remained lower through wk 16. Rate of starter consumption was also lower in AC calves at wk 16. Body weight also was also lower for AC calves from wk 5 through 16. Blood hemoglobin and hematocrit were lower in AC calves, but other blood characteristics were not different. Rumen volume increased with age and tended to be greater in BL calves. Passage rate and papillae length and width were not different between diets, but AC calves experienced a greater degree of tissue degradation. Ruminal acidosis symptoms in calves appear similar to those in adult cattle, and the etiology of the disease seems to follow similar mechanisms. It is clear from this study that symptoms can be moderated by diet, but further research is needed to determine whether symptoms can be nutritionally prevented or whether calves that experience ruminal acidosis are more susceptible to the disease as adults.

Throughout the Southern Great Plains, wheat is managed frequently as a dual-purpose crop, but this production paradigm is not necessarily applicable throughout other regions of the United States, and a wider array of management options can be considered for forage-only uses of cereal grains. Our objectives were to assess the fall-growth potential of wheat (Triticum aestivum L.), triticale (X Triticosecale Wittmack), and oat (Avena sativa L.) cultivars in Wisconsin, and then to further evaluate and compare the fiber composition and TDN of these fall-grown forages. For 2006, yields of DM for all cultivars increased quadratically (P ≤ 0.048) over fall harvest dates, reaching a maximum of 3,967 kg/ha for Ogle oat. All oat cultivars exhibited stem elongation and also displayed a collective 2 to 1 yield advantage over vegetative wheat cultivars on the final (October 30) harvest date. Growing conditions were more favorable during 2007, and yields were improved for all cultivars. Yields of DM for all cultivars increased quadratically (P ≤ 0.021) across harvest dates, and oat cultivars maintained the identical 2 to 1 yield advantage over wheat cultivars (6,275 vs. 3,203 kg/ha) that was observed for 2006. Triticale exhibited yields intermediate between oat and wheat during both years. Concentrations of NDF increased quadratically (P ≤ 0.012) across harvest dates for all cultivars during both years of the experiment; however, these increases occurred primarily between mid September and early October with limited responses thereafter. Oat and triticale cultivars had greater (P < 0.001) concentrations of NDF than wheat cultivars on 5 of 6 harvest dates throughout the experiment. Estimates of TDN exhibited various polynomial responses to harvest date during 2006, but the magnitude of these changes was relatively small. During 2007, TDN declined linearly (P ≤ 0.038) for grain-type oat, but no relationship with harvest date was observed for other cultivars (P ≥ 0.072), including forage-type oat. Although TDN estimates generally were relatively static across harvest dates, the concentrations of truly digestible components constituting the total TDN pool were quite fluid. Generally, reductions of truly digestible CP were offset by increases in truly digestible nonfiber carbohydrate, truly digestible fiber, or both. The relatively stable energy densities for cereal-grain cultivars observed across harvest dates suggest that a broad window of opportunity exists for usage, including a single harvest as silage. Copyright © 2010. American Society of Animal Science .

Dairy cattle often make poor use of protein when offered diets comprising high proportions of alfalfa (Medicago sativa L.) hay or silage because nonprotein N formed during forage conservation and ruminal fermentation exceeds requirements for rumen microbial protein synthesis; however, condensed tannins (CT) may reduce proteolysis in the silo and in the rumen, thereby potentially improving the efficiency of crude protein (CP) use in ruminant diets. Two harvests, yielding 12 hays and 12 silages made from alfalfa and birdsfoot trefoil (Lotus corniculatus L.) that varied in concentrations of CT, were evaluated for in situ disappearance kinetics of CP in 6 ruminally cannulated lactating Holstein dairy cows (627 ± 56.3 kg). Prior to conservation, alfalfa contained no detectable CT, whereas CT in fresh lyophilized birdsfoot trefoil ranged from 1.16 to 2.77% of dry matter, as determined by a modified acetone-butanol-HCl assay. Percentages of CP remaining at each incubation time were fitted to nonlinear regression models with or without a discrete lag time. Effective ruminal disappearance of CP (rumen-degradable protein, RDP) was calculated by 3 procedures that included (1) no discrete lag (RDPNL), (2) discrete lag (RDPL), and (3) discrete lag with a lag adjustment (RDPLADJ). Regardless of the calculation method, RDP declined linearly with increasing CT concentrations (R(2)=0.62 to 0.97). Generally, tests of homogeneity showed that conservation type (hay or silage) or harvest (silage only) affected intercepts, but not slopes in regressions of RDP on CT. A positive relationship between lag time and CT suggests that the RDPLADJ approach may be most appropriate for calculating RDP for legumes containing tannins. With this approach, regression intercepts were mainly affected by conservation method, and RDPLADJ averaged 77.5 and 88.7% of CP for hay and silage, respectively, when no CT was present. Greater estimates of RDP for silages were related to extensive proteolysis in laboratory silos resulting in conversions of protein into nonprotein N forms, which readily washed out of Dacron bags. When RDPLADJ and CT were expressed on a CP basis, regression slopes indicated that each unit of CT protected 0.61 units of CP from ruminal degradation in hays and silages. Applying this relationship to a typical mid-maturity forage legume containing 21% CP suggests that a CT concentration of 3.8% of DM would be required to reduce RDP from 81% to a 70% target considered optimal for improving protein utilization and milk yields by dairy cattle.