Effect of monensin and live-cell yeast supplementation on lactation performance, feeding behavior, and total tract nutrient digestibility by dairy cows

The objective of this study was to evaluate the effects of supplementing monensin (MON:19.8 g/Mg DM TMR) and Saccharomyces cerevisiae CNCM I-1077 (LCY: Saccharomyces cerevisiae CNCM I-1077; 1 × 1010 cfu/hd/d) on lactation performance, feeding behavior, and total-tract nutrient digestibility of high-producing dairy cows. Sixty-four multiparous Holstein cows (3.2 ± 1.5 lactations; 97 ± 16 DIM, and 724 ± 68 kg of BW at covariate period initiation) and 32 gate feeders were enrolled in a study with a completely randomized design and a 2 × 2 factorial arrangement. Cows and gate feeders were randomly assigned to treatments (16 cows and 8 gate feeds per treatment). Cows were allowed 2 wk to acclimate to feeding gates followed by a 2 wk covariate period. During the acclimation and covariate periods, all cows were fed a diet containing MON and LCY. Following the covariate period, cows were enrolled in a 10 wk treatment period during which cows were randomly assigned to 1 of 4 treatments: 1) a combination of MON and LCY (MON-LCY), 2) MON alone, 3) LCY alone, or 4) neither MON nor LCY (CON-CON). Data were analyzed using a mixed model with week as a repeated measure and fixed effects of MON, LCY, week, and all their interactions. Cow (treatment) was included as a random effect. The average covariate period value of each variable was used as a covariate. Three-way interactions were observed for DMI and feed efficiency. Dry matter intake decreased from wk 4-5 and 8-10 in MON-LCY cows compared with CON-CON. No treatment differences were observed for actual or component-corrected milk yield or milk components, except for a tendency for LCY to decrease milk fat yield. Feed efficiency was greater for MON-LCY relative to CON-CON in 4 of 10 weeks. Interactions between MON and LCY were observed for dry matter and organic matter digestibility, where both were lower for CON-CON than other treatments. Under the conditions of the present study, feeding dairy cows in a high feed bunk density a combination of MON and LCY can decrease intake and improve feed efficiency without affecting milk production or components. Additionally, monensin and live-cell yeasts may each improve total-tract digestibility based on improvements in dry matter and organic matter digestibility.

Effect of a genetically-modified corn hybrid with alpha-amylase and storage length on fermentation profile and starch disappearance of whole-plant corn silage and earlage

Two experiments were conducted to evaluate the effects of a genetically-modified corn hybrid with α-amylase expressed in the kernel (AMY) on fermentation profile, aerobic stability, nutrient composition, and starch disappearance of whole-plant corn silage (WPCS) and earlage. Both hybrids, AMY and its isogenic counterpart (ISO), were grown in 10 replicated plots (5 for WPCS and 5 for earlage). Samples of each plot were collected at harvest, homogenized, and divided into 5 subsamples which were randomly assigned to 5 storage lengths (0, 30, 60, 90 and 120 d). Both data sets (WPCS and earlage), were analyzed separately as a completely randomized block design in a factorial arrangement of treatments, with a model including the fixed effects of hybrid, storage length and their interaction and the random effect of block. Minor differences on fermentation profile were observed between AMY and ISO for WPCS and earlage. An interaction between hybrid and storage length was observed for DM losses in WPCS, where losses were similar at 30, 60 and 90 d, but lower for AMY compared with ISO at 120 d. No effect of hybrid was observed on yeast and mold counts for WPCS or earlage. Aerobic stability of WPCS was greater for AMY than ISO. For earlage, AMY had greater DM losses and aerobic stability than ISO. An interaction between hybrid and storage length was observed for ammonia-N in both WPCS and earlage, where ammonia-N was similar at 0 d but greater for AMY than ISO throughout later storage lengths. A similar interaction was observed for water-soluble carbohydrates (WSC) concentrations in WPCS, where ISO had greater WSC than AMY at 0 d but was similar throughout later storage lengths. Whereas AMY earlage had greater WSC concentration throughout storage length, but lesser magnitude after ensiling. Starch concentration was greater for AMY than ISO in WPCS and earlage. Greater starch disappearances at 0 h and 6 h were observed for ISO in WPCS and earlage. Minor effects on fermentation profile, microbial counts, aerobic stability and nutrient composition suggests that AMY can be ensiled for prolonged periods with no concerns for undesirable fermentation or nutrient losses. However, in situ starch disappearance was lower for AMY compared with ISO.

Effects of endosperm type and storage length of whole-plant corn silage on nitrogen fraction, fermentation products, zein profile, and starch digestibility

Zeins are commercially important proteins found in corn endosperms. The objective of this study was to evaluate the effect of altering zein levels in corn inbred lines carrying endosperm mutations with differential allelic dosage and analyze the effects on the composition, nutritive value, and starch digestibility of whole-plant corn silage (WPCS) at 5 storage lengths. Three inbred lines carrying 3 different endosperm modifiers (opaque-2 [o2], floury-2 [fl2], and soft endosperm-1 [h1]) were pollinated with 2 pollen sources to form pairs of near-isogenic lines with either 2 or 3 doses of the mutant allele for each endosperm modifier. The experiment was designed as a split-plot design with 3 replications. Pollinated genotype was the main plot factor, and storage length was the subplot-level factor. Agronomic precautions were taken to mimic hybrid WPCS to the extent possible. Samples were collected at approximately 30% dry matter (DM) using a forage harvester and ensiled in heat-sealed plastic bags for 0, 30, 60, 120, and 240 d. Thus, the experiment consisted of 30 treatments (6 genotypes × 5 storage lengths) and 90 ensiling units (3 replications per treatment). Measurements included nutrient analysis, including crude protein, soluble crude protein, amylase-treated neutral detergent fiber, acid detergent fiber, lignin, starch, fermentation end products, zein concentration, and in vitro starch digestibility (ivSD). The nutritional profile of the inbred-based silage samples was similar to hybrid values reported in literature. Significant differences were found in fresh (unfermented) sample kernels for endosperm vitreousness and zein profiles between and within isogenic pairs. The o2 homozygous (3 doses of mutant allele) had the highest reduction in vitreousness level (74.5 to 38%) and zein concentration (6.2 to 4.7% of DM) compared with the heterozygous counterpart (2 doses of mutant allele). All genotypes showed significant reduction of total zeins and α-zeins during progressive storage length. In vitro starch digestibility increased with storage length and had significant effects of genotype and storage length but not for genotype by storage length interaction, which suggests that the storage period did not attenuate the difference in ivSD between near-isogenic pairs caused by zeins in WPCS. Both total zeins and α-zeins showed a strong negative correlation with ivSD, which agrees with the general hypothesis that the degradation of zeins increases ruminal starch degradability. Homozygous o2 was the only mutant with significantly higher ivSD compared with the heterozygous version, which suggests that, if all other conditions remain constant in a WPCS systems, substantial reductions in endosperm α-zeins are required to significantly improve ivSD in the silo.

Effects of direct-fed microbial supplementation on performance and immune parameters of lactating dairy cows

We evaluated the effects of supplementing bacterial direct-fed microbial (DFM) on performance, apparent total-tract digestibility, rumen fermentation, and immune parameters of lactating dairy cows. One hundred fourteen multiparous Holstein cows (41 ± 7 DIM) were used in a randomized complete block design with an experiment comprising 14 d of a covariate (pre-experimental sample and data collection) and 91 d of an experimental period. Cows were blocked based on energy-corrected milk (ECM) yield during the covariate period and the following treatments were randomly assigned within each block: (1) control (CON), corn silage-based total mixed ration without DFM; (2) PRO-A, basal diet top-dressed with a mixture of Lactobacillus animalis and Propionibacterium freudenreichii at 3 × 109 cfu/d; and 3) PRO-B, basal diet top-dressed with a mixture of L. animalis, P. freudenreichii, Bacillus subtilis, and Bacillus licheniformis at 11.8 × 109 cfu/d. Milk yield, dry matter intake (DMI), and body weight were measured daily, while milk samples for component analysis were taken on 2 consecutive days of each week of data collection. Feces, urine, rumen, and blood samples were taken during the covariate period, wk 4, 7, 10, and 13 for estimation of digestibility, N-partitioning, rumen fermentation, plasma nutrient status and immune parameters. Treatments had no effect on DMI and milk yield. Fat-corrected milk (3.5% FCM) and milk fat yield were improved with PRO-B, while milk fat percent and feed efficiency (ECM/DMI) tended to increase with PRO-B compared with PRO-A and CON. Crude fat digestibility was greater with PRO-B compared with CON. Feeding CON and PRO-A resulted in higher total volatile fatty acid concentration relative to PRO-B. Percentage of neutrophils tended to be reduced with PRO-A compared with CON and PRO-B. The mean fluorescence intensity (MFI) of anti-CD44 antibody on granulocytes tended to be higher in PRO-B compared with CON. The MFI of anti-CD62L antibody on CD8+ T cells was lower in PRO-A than PRO-B, with PRO-A also showing a tendency to be lower than CON. This study indicates the potential of DFM to improve fat digestibility with consequential improvement in fat corrected milk yield, feed efficiency and milk fat yield by lactating dairy cows. The study findings also indicate that dietary supplementation with DFM may augment immune parameters or activation of immune cells, including granulocytes and T cells; however, the overall effects on immune parameters are inconclusive.

Physical effectiveness of corn silage fractions stratified with the Penn State Particle Separator for lactating dairy cows

This study evaluated the physical effectiveness of whole-plant corn silage (CS) particles stratified with the Penn State Particle Separator, composed of 19- and 8-mm-diameter sieves and a pan, for lactating dairy cows. Eight Holstein cows (27.6 ± 2.8 kg/d of milk, 611 ± 74 kg body weight; 152 ± 83 d in milk) were assigned to two 4 × 4 Latin squares (22-d periods, 16-d adaptation), where one square was formed with rumen-cannulated cows. Three CS particle fractions were manually isolated using the 8- and 19-mm diameter sieves and re-ensiled in 200-L drums. The 4 experimental diets were (% dry matter): (1) CON (control): 17% forage neutral detergent fiber (NDF) from CS (basal roughage), 31.5% starch, and 31.9% NDF; (2) PSPan: 17% forage NDF from CS + 9% NDF from CS particles <8 mm, 25.9% starch, and 37.9% NDF; (3) PS8: 17% forage NDF from CS + 9% NDF from CS particles 8 to 19 mm, 25.5% starch, and 38.3% NDF; and (4) PS19: 17% forage NDF from CS + 9% NDF from CS particles >19 mm, 24.9% starch, and 38.8% NDF. Cows fed PS8 had greater dry matter intake and energy-corrected milk yield (22.4 and 26.9 kg/d, respectively) than cows fed CON (20.8 and 24.7 kg/d) and PS19 (21.2 and 24.8 kg/d), but no difference was detected between PSPan (21.6 and 25.8 kg/d) and other treatments. Milk fat concentration was greater for PS8 than CON, with intermediate values for PSPan and PS19. Milk fat yield was greater for cows fed PS8 than CON and PS19, and cows fed PSPan secreted more fat than CON cows but were not different from cows fed the other 2 diets. Cows fed CON had a lower meal frequency than cows fed PSPan, shorter meal and rumination times than PS8, and greater meal size and lower rates of rumination and chewing than the other 3 diets. Total chewing per unit of NDF was higher for PS8 than PSPan, although neither treatment differed from CON or PS19. Cows fed PS19 had higher refusal of feed particles >19 mm than cows fed CON and PSPan. The refusal of dietary NDF and undigested NDF in favor of starch were all greater for PS19 than on the other treatments. Cows fed PS19 had a greater proportion of the swallowed bolus and rumen digesta with particles >19 mm than the other 3 diets. Cows fed CON had the lowest ruminal pH and greatest lactate concentration relative to the other 3 diets. Plasma lipopolysaccharide was higher for cows fed CON and PSPan than for cows fed PS8 and PS19, and serum d-lactate tended to be lower on PSPan than for CON and PS8. In summary, the inclusion of CS fractions in a low-forage fiber diet (CON) reduced signs of ruminal acidosis. Compared with CS NDF <8 and >19 mm, CS NDF with 8- to 19-mm length promoted better rumen health and performance of dairy cows. These results highlight the importance of adjusting CS harvest and formulating dairy diets based on the proportion of particles retained between the 8- and 19-mm sieves.

Individual animal variability in rumination, activity, and lying behavior during the periparturient period of dairy cattle

The aim of the current study was to determine individual animal variability in rumination, activity, and lying behavior during the periparturient period within the context of dairy cattle nutrition, social, and physical environment. Holstein animals (nulliparous = 77, parous = 219) from one sand-bedded, freestall dairy in northwest Wisconsin were enrolled -17 d in milk (DIM, d 0 = calving), when they were fitted with an automated monitoring device (Hi-Tag, SCR Engineers Ltd.). At -11 DIM, animals were fitted with HOBO Pendant G Data Loggers. The HOBO Pendant G Data Loggers were fitted 6 d later because they were set up to collect data for 22 d (d -11 to 11), to avoid constant handling of the animals that could alter their behavior. Prepartum, nulliparous and parous animals were housed separately. Postpartum (1 to 17 ± 3 DIM), primiparous and multiparous cows were commingled. Samples of the total mixed ration were submitted for wet chemistry analysis and determination of physically effective NDF (peNDF). Temperature and humidity data were collected using RH Temp probes (HOBO Pro Series) installed in each of the pens, and the percentages of 30-min intervals within a day with temperature-humidity index ≥68 (PctTHI68) were calculated. Stocking density (cows per stall) during the pre- and postpartum periods were calculated daily. Prepartum data from nulliparous and parous animals were analyzed separately, and postpartum data from primiparous and multiparous animals were analyzed together. Prepartum, nulliparous and parous animals explained 83.9 and 64.5% of the variability in rumination, 70.7 and 60.9% of the variability in activity, and 38.1 and 63.6% of the variability in lying time, respectively. Postpartum, animal explained 49.7, 56.8, and 35.6% of the variability in rumination, activity, and lying time, respectively. Although stocking density, PctTHI68, peNDF, crude protein, and ether extract were associated with the variability in rumination, activity, and lying time, they explained ≤6.6% of the daily variability in these behaviors. We conclude that, within the conditions of the collaborating commercial herd, individual animal is the most important factor explaining daily variability in rumination, activity, and lying time.

Effects of exogenous amylolytic or fibrolytic enzymes inclusion on in vitro fermentation of lactating dairy cow diets in a dual-flow continuous-culture system

The objective of this study was to determine the effects of including exogenous amylolytic or fibrolytic enzymes in a diet for high-producing dairy cows on in vitro ruminal fermentation. Eight dual-flow continuous-culture fermentors were used in a replicated 4 × 4 Latin square. The treatments were control (CON), a xylanase and glucanase mixture (T1), an α-amylase mixture (T2), or a xylanase, glucanase, and α-amylase mixture (T3). Treatments were included at a rate of 0.008% of diet dry matter (DM) for T1 and T2 and at 0.02% for T3. All treatments replaced the equivalent amount of soybean meal in the diet compared with CON. All diets were balanced to have the same nutrient composition [30.2% neutral detergent fiber (NDF), 16.1% crude protein (CP), and 30% starch; DM basis], and fermentors were fed 106 g/d divided into 2 feedings. At each feeding, T2 was pipetted into the respective fermentor and an equivalent amount of deionized water was added to each fermentor to eliminate potential variation. Experimental periods were 10 d (7 d for adaptation and 3 d for sample collection). Composite samples of daily effluent were collected and analyzed for volatile fatty acids (VFA), NH₃-N, and lactate concentrations, degradability of DM, organic matter, NDF, CP, and starch, and flow and metabolism of N. Samples of fermentor contents were collected from each fermentor at 0, 1, 2, 4, 6, and 8 h after feeding to determine kinetics of pH, NH₃-N, lactate, and VFA concentrations over time. All data were analyzed using PROC GLIMMIX of SAS (SAS Institute Inc.), and the repeated variable of time was included for kinetics measurements. Treatment did not affect mean pH, degradability, N flow and metabolism, or the concentrations of VFA, NH₃-N, or lactate in the effluent samples. Treatment did not affect pH, acetate:propionate ratio, or the concentrations of lactate, NH₃-N, total VFA, acetate, propionate, butyrate, isobutyrate, valerate, or caproate. However, the concentration of total VFA tended to change at each time point depending upon the treatment, and T2 tended to have a greater proportion of 2-methylbutyrate and isovalerate than CON, T1, or T3. As 2-methylbutyrate and isovalerate are branched-chain VFA that are synthesized from branched-chain amino acids, T2 may have an increased fermentation of branched-chain amino acids or decreased uptake by fibrolytic microorganisms. Although we did not observe changes in N metabolism due to the enzymes, there could be changes in microbial populations that utilize branched-chain VFA. Overall, the tested enzymes did not improve in vitro ruminal fermentation in the diet of high-producing dairy cows.

Effects of Aspergillus oryzae prebiotic on animal performance, nutrients digestibility, and feeding behavior of backgrounding beef heifers fed with either a sorghum silage- or a byproducts-based diet

Eighty-four Angus crossbred heifers (13 ± 1 mo of age, 329.5 ± 61.92 kg of body weight [BW]) were used in a generalized randomized block design with a 2 × 2 factorial arrangement of treatments. The factors evaluated were: 1) diet type (whole plant sorghum silage [SS] vs. byproducts-based [BP]), and 2) feed additive: Aspergillus oryzae prebiotic (AOP; 2 g/d) vs. Negative control (CTL; 0 g/d), resulting in four treatments: sorghum silage-control (SC), sorghum silage-AOP (SA), byproducts-control (BC), and byproducts-AOP (BA). Heifers were stratified by body weight (BW), randomly assigned to treatments (21 heifers per treatment) and housed in 12 pens equipped with two GrowSafe feed bunks each to measure individual dry matter intake (DMI). After a 14-d adaptation, BW was measured every 14 d for 56 d. Chewing activity was monitored through collar-mounted HR-Tags (heat-related tags). Following the performance period, apparent total tract digestibility was measured in 40 heifers, using indigestible neutral detergent fiber as a marker. Heifers fed with the BP diets had greater DMI (2.92% vs. 2.59% of BW, P < 0.01) and average daily gain (ADG; 1.16 vs. 0.68 kg, P ≤ 0.01) than heifers fed with SS diets. Compared with BP-fed animals, heifers consuming the SS diets had 23 more visits/d to the feed bunks (P ≤ 0.01), consumed 53% less dry matter on each visit (P ≤ 0.01), and spent 39% more min chewing/d and 63% more min chewing/kg of DMI (P ≤ 0.01). However, chewing measured in min/kg of neutral detergent fiber intake was not affected by treatment (average 111.3 min/kg of NDF intake). Feeding AOP improved gain:feed (GF) by 15% in BP-fed heifers (0.120 vs. 0.104 kg/kg; P < 0.05). Inclusion of AOP increased organic matter digestibility (OMD) in SS diets (55.88% vs. 49.83%; P < 0.01), whereas it decreased OMD in BP diets (61.67% vs. 65.77%; P < 0.05). In conclusion, ADG and GF of BP-fed heifers was greater than SS-fed heifers, and GF was greater with AOP supplementation in BP-fed heifers. Improvement in GF in BP-fed heifers was likely not related to differences in nutrient digestibility as AOP inclusion did not enhance digestibility in the BP diet. Additionally, the effects of the AOP inclusion appear to be diet-dependent, where the 15% improvement in GF by AOP occurred in heifers fed with the more fermentable diet. Therefore, further research should explore the mechanisms responsible for the observed improvements in growth performance when feeding AOP to BP-fed heifers.

Effect of microbial inoculation and storage length on the fermentation profile and nutritive value of high-moisture corn ensiled at two different dry matter concentrations

The objective of this experiment was to evaluate the effect of microbial inoculation and storage length on the fermentation profile and nutrient composition of high-moisture corn (HMC) ensiled at two different dry matter (DM) concentrations. High-moisture corn was harvested when kernel DM concentrations were approaching 65% as-fed, and either left undried (HMC65; 67.6% DM) or dried at 40°C to approximately 70% DM (HMC70; 71.0% DM), and then ensiled in quadruplicate vacuum pouches untreated (CON) or after one of the following inoculant treatments: 6.36 × 10 5 cfu of Lentilactobacillus buchneri DSM 12856, Lactiplantibacillus plantarum DSM 12836, and Pediococcus acidilactici DSM 16243 per g of HMC (LBLP); or 3.0 × 10 5 cfu of L. buchneri DSM 12856, Lentilactobacillus diolivorans DSM 32074, and P. acidilactici DSM 16243 per g of HMC (LBLD). Vacuum pouches were allowed to ferment for 7, 14, 28, or 56 d. A three-way interaction was observed (P = 0.01) for the pH of HMC, where CON for HMC70 was greatest across storage lengths and HMC65 treatments generally had a lower pH than other treatments. Concentrations of total acids were greater (P = 0.001) in HMC65 than HMC70 and greater (P = 0.001) in HMC treated with LBLP and LBLD than CON. An interaction between DM concentration, microbial inoculation, and storage length was observed (P = 0.05) for concentrations of acetic acid. At 14 d, acetic acid concentrations were greater in HMC65 treated with LBLD than other treatments. Likewise, at 56 d, concentrations of acetic acid were greatest in HMC65 treated with LBLD, followed by HMC70 treated with LBLD. An interaction between DM concentration, microbial inoculation, and storage length was observed (P = 0.05) for 7-h starch disappearance (starchD). Across all DM concentration and inoculant treatment combinations, starchD increased with increasing storage length. StarchD was also generally greater for HMC65 treatments compared to HMC70, with small differences among inoculants. Results suggest that microbial inoculation can improve fermentation of HMC by increasing the production of antifungal acetic acid, but that DM concentration at ensiling remains a primary determinant of HMC fermentability.

Effects of season, variety type, and trait on dry matter yield, nutrient composition, and predicted intake and milk yield of whole-plant sorghum forage

Sorghum forage is an important alternative to high-quality forage in regions where climatic and soil conditions are less desirable for corn production for silage and producing comparable nutritive value is challenging. The objective of this experiment was to assess the effects of season (spring vs. summer), sorghum variety type (forage sorghum vs. sorghum-sudangrass), and trait [brown midrib (BMR) vs. non-BMR] on dry matter (DM) yield, nutrient composition, and predicted intake and milk yield of whole-plant sorghum forage grown in Florida from 2008 to 2019. Whole-plant sorghum forage was harvested at a targeted 32% of DM, and each year, spring (April) and summer (July) trials were established. A total of 300 forage sorghum and 137 sorghum-sudangrass hybrids were tested for a total of 437 hybrids, of which 199 hybrids contained the BMR trait and 238 were non-BMR. An interaction between season and sorghum variety type was observed for DM yield. Dry matter yield was greater for the spring season than the summer season, with sorghum-sudangrass outperforming forage sorghum only during the spring season. In addition, BMR hybrids had a lower DM yield than non-BMR hybrids, regardless of season and variety type. An interaction between season and trait was observed for predicted neutral detergent fiber digestibility after 30 h of incubation in rumen fluid (NDFD_30h). Predicted NDFD_30h was greater for BMR sorghum in comparison to non-BMR sorghum, but BMR sorghum had slightly greater predicted NDFD_30h when grown in the spring than summer, whereas no seasonal differences were found for predicted NDFD_30h across non-BMR sorghum. An interaction between season, variety type, and trait was observed for predicted dry matter intake at 45 (DMI₄₅), 55 (DMI₅₅), and 65 (DMI₆₅) kg of milk/d. Predicted DMI₄₅ and DMI₅₅ were greater for spring BMR forage sorghum than for spring and summer non-BMR sorghum-sudangrass and were greater for spring BMR forage sorghum than for summer BMR sorghum-sudangrass. Predicted DMI₆₅ was greater for BMR forage sorghum in comparison to all non-BMR hybrids in the spring. Additionally, spring BMR forage sorghum was greater than summer sorghum-sudangrass regardless of trait. An interaction between season and sorghum variety type was observed for milk yield per megagram of forage. Milk yield per megagram of forage was greatest for spring forage sorghum. Sorghum variety type and trait selection are crucial to minimize differences in forage nutritive value of sorghum forage between seasons and improve the performance of high-producing dairy cows.

Effects of sucrose and lactose as partial replacement to corn in lactating dairy cow diets. A review

Carbohydrates are one of the three macronutrients that provides energy in diets and are classified by their structures. Starch is a nonstructural carbohydrate and polysaccharide made of glucose monomers used for storage in plant cells. When starch makes up greater than 30% of the DM in diets there can be adverse effects on NDF digestibility due to decreases in ruminal pH. Sugars are water soluble carbohydrates that consist of monosaccharide and disaccharide units. Sugars ferment faster than starch because microorganisms in the rumen can ferment carbohydrates at different rates depending on their structure; however, this has not been shown to have negative effects on the ruminal pH. Sources of sugars such as molasses (sucrose) or whey (lactose) can be included in the diet as a partial replacement for starch in dairy cow diets. The purpose of replacing starch with sugars in a diet would be to add differing sources of carbohydrates in the diet to allow for continual fermentation of carbohydrates by the microorganisms in the rumen. It has been seen in studies and previous literature that the partial replacement of starch with sugars has the potential to maintain the ruminal environment and milk yield and composition in dairy cows without reducing NDF digestibility. The objective of this review is to evaluate the effects of partially replacing starch with sugars in dairy diets and its implication on ruminal fermentation, nutrient utilization, milk production, and feeding replacement strategy.

Effect of cutting height, microbial inoculation, and storage length on fermentation profile and nutrient composition of whole-plant corn silage

This study aimed to evaluate the effects of cutting height, heterofermentative microbial inoculants, and storage length on the fermentation profile and nutrient composition of whole-plant corn silage. The experiment was a completely randomized design with a 2 (cutting height) × 3 (microbial inoculation) × 5 (storage length) factorial arrangement of treatments. Corn forage was harvested at two cutting heights: either 25 cm (REG) or 65 cm (HI). Then, forage was inoculated with one of three microbial inoculants: 1) 300,000 CFU/g of fresh forage of Pediococcus acidilactici DSM 16243, Lentilactobacillus buchneri DSM 12856, and L. diolivorans DSM 32074 (LBLD; Bonsilage Speed inoculant, Provita Supplements Inc., Mendota Heights, MN), 2) 500,000 CFU/g of fresh forage of Lactiplantibacillus plantarum DSM 12837 and Lentilactobacillus buchneri DSM 16774 (LPLB; Bonsilage Corn + WS inoculant, Provita Supplements Inc., Mendota Heights, MN), or 3) distilled water (CON). Lastly, forage was randomly assigned to ferment for 5, 7, 14, 28, or 56 d of storage in vacuum-sealed bags. Silage pH was affected by a three-way interaction (P = 0.01), where CON treatments decreased continually over time while LPLB and LBLD began to increase at later storage lengths. Acetic acid concentration was greater (P = 0.001) in LPLB and LBLD than CON silage after 56 d of storage. Silage treated with LBLD did not have detectable levels of propionic acid (P &gt; 0.05), although 1-propanol concentration was greater (P = 0.001) in LBLD treatments after 56 d of storage. The concentrations of total acids and acetic acid were greater (P = 0.01 and P = 0.001, respectively) for REG silage compared to HI. Additionally, HI silage had greater (P = 0.001 and P = 0.001, respectively) concentrations of dry matter (DM) and starch, while neutral detergent fiber (aNDF) and lignin concentrations were lower (P = 0.001 and P = 0.001, respectively) in HI silage compared to REG silage. Lastly, HI silage had a greater (P = 0.001) NDF digestibility than REG silage. The results of this study demonstrate that increasing cutting height can improve nutrient composition of whole-plant corn silage. Additionally, results demonstrate heterofermentative microbial inoculants can be used to shift silage fermentation to the production of lactic and acetic acids.

Effects of partially replacing dietary corn with molasses, condensed whey permeate, or treated condensed whey permeate on ruminal microbial fermentation

Corn is a feedstuff commonly fed to dairy cows as a source of energy. The objective of this study was to evaluate whether partially replacing dietary corn with molasses or condensed whey permeate, in lactating dairy cow diets in a dual-flow continuous culture system, can maintain nutrient digestibility by ruminal microorganisms. Furthermore, this study evaluated whether treating condensed whey permeate before feeding could aid the fermentation of the condensed whey permeate in the rumen. Eight fermentors were used in a 4 × 4 replicated Latin square with 4 periods of 10 d each. The control diet (CON) was formulated with corn grain, and the other diets were formulated by replacing corn grain with either sugarcane molasses (MOL), condensed whey permeate (CWP), or treated condensed whey permeate (TCWP). Diets were formulated by replacing 4% of the diet dry matter (DM) in the form of starch from corn with sugars from the byproducts. Sugars were defined as water-soluble carbohydrates (WSC) in the rations. The fermentors were fed 52 g of DM twice daily of diets containing 17% crude protein, 28% neutral detergent fiber, and 45% nonfiber carbohydrates. Liquid treatments were pipetted into each fermentor. After 7 d of adaptation, samples were collected for analyses of volatile fatty acids (VFA), lactate, and ammonia, and fermentors' pH were measured at time points after the morning feeding for 3 d. Pooled samples from effluent containers were collected for similar analyses, nutrient flow, and N metabolism. Data were statistically analyzed using Proc MIXED of SAS version 9.4 (SAS Institute Inc.); fixed effects included treatment and time, and random effects included fermentor, period, and square. The interaction of treatment and time was included for the kinetics samples. The TCWP and MOL treatments maintained greater fermentor pH compared with CWP. Total VFA concentration was increased in CWP compared with MOL. The acetate:propionate ratio was increased in TCWP compared with CON, due to tendencies of increased acetate molar proportion and decreased propionate molar proportion in TCWP. Lactate concentration was increased in MOL. Digestibility of WSC was increased in the diets that replaced corn with byproducts. The partial replacement of 4% of DM from corn starch with the sugars in byproducts had minimal effects on ruminal microbial fermentation and increased pH. Treated CWP had similar effects to molasses.

Lactational performance of dairy cows in response to supplementing N-acetyl-l-methionine as source of rumen-protected methionine

The objective of this experiment was to evaluate the effects of supplementing a rumen-protected source of Met, N-acetyl-l-methionine (NALM), on lactational performance and nitrogen metabolism in early- to mid-lactation dairy cows. Sixty multiparous Holstein dairy cows in early lactation (27 ± 4.3 d in milk, SD) were assigned to 4 treatments in a randomized complete block design. Cows were blocked by actual milk yield. Treatments were as follows: (1) no NALM (control); (2) 15 g/d of NALM (NALM15); (3) 30 g/d of NALM (NALM30); and (4) 45 g/d of NALM (NALM45). Diets were formulated using a Cornell Net Carbohydrate and Protein System (CNCPS) v.6.5 model software to meet or exceed nutritional requirements of lactating dairy cows producing 42 kg/d of milk and to undersupply metabolizable Met (control) or supply incremental amounts of NALM. The digestible Met (dMet) supply for control, NALM15, NALM30, and NALM45 were 54.7, 59.8, 64.7, and 72.2 g/d, respectively. The supply of dMet was 88, 94, 104, and 115% of dMet requirement for control, NALM15, NALM30, and NALM45, respectively. Milk yield data were collected, dry matter intake (DMI) was measured daily, and milk samples were collected twice per week for 22 wk. Blood, ruminal fluid, urine, and fecal samples were collected during the covariate period and during wk 4, 8, and 16. Data were analyzed using the GLIMMIX procedure of SAS (SAS Institute) using covariates in the model for all variables except body weight. Linear, quadratic, and cubic contrasts were also tested. Treatments did not affect DMI, milk yield, and milk component concentration and yield; however, feed efficiency expressed as milk yield per DMI and 3.5% fat-corrected milk per DMI were quadratically affected, with greater response observed for NALM15 and NALM30 compared with control. Acetate proportion linearly increased, whereas propionate proportion linearly decreased with NALM supplementation. Blood urea nitrogen linearly decreased with NALM supplementation. Total plasma essential AA concentrations were quadratically affected, as greater values were observed for control and NALM45 than other treatments. Plasma Met concentration was quadratically affected as lower levels were observed with NALM15, whereas Met concentrations increased with NALM45 compared with control. Nitrogen utilization efficiency and apparent total-tract nutrient digestibility were not affected by treatment. Supplementation of NALM at 15 or 30 g/head per day resulted in the greatest improvements in feed efficiency without affecting N metabolism of early- to mid-lactation dairy cows.

Effects of lignocellulolytic enzymes on the fermentation profile, chemical composition, and in situ ruminal disappearance of whole-plant corn silage

The objective of this study was to examine the enzyme activities of an enzymatic complex produced by Pleurotus ostreatus in different pH and the effects of adding increased application rates of this enzymatic complex on the fermentation profile, chemical composition, and in situ ruminal disappearance of whole-plant corn silage (WPCS) at the onset of fermentation and 30 d after ensiling. The lignocellulolytic enzymatic complex was obtained through in vitro cultivation of P. ostreatus. In the first experiment, the activities of laccase, lignin peroxidase (LiP), manganese peroxidase, endo- and exo-glucanase, xylanase, and mannanase were determined at pH 3, 4, 5, and 6. In the second experiment, five application rates of enzymatic complex were tested in a randomized complete block design (0, 9, 18, 27, and 36 mg of lignocellulosic enzymes/kg of fresh whole-plant corn [WPC], corresponding to 0, 0.587, 1.156, 1.734, and 2.312 g of enzymatic complex/kg of fresh WPC, respectively). There were four replicates per treatment (vacuum-sealed bags) per opening time. Bags were opened 1, 2, 3, and 7 d after ensiling (onset of fermentation period) and 30 d after ensiling to evaluate the fermentation profile, chemical composition, and in situ dry matter and neutral fiber detergent disappearance of WPCS. Laccase had the greatest activity at pH 5 (P < 0.01), whereas manganese peroxidase and LiP had the greatest activity at pH 4 (P < 0.01; P < 0.01). There was no effect of the rate of application of enzymatic complex, at the onset of fermentation, on the fermentation profile (P > 0.21), and chemical composition (P > 0.36). The concentration of water-soluble carbohydrate quadratically decreased (P < 0.01) over the ensiling time at the onset of fermentation, leading to a quadratic increase of lactic acid (P = 0.02) and a linear increase of acetic acid (P = 0.02) throughout fermentation. Consequently, pH quadratically decreased (P < 0.01). Lignin concentration linearly decreased (P = 0.04) with the enzymatic complex application rates at 30 d of storage; however, other nutrients and fermentation profiles did not change (P > 0.11) with the enzymatic complex application rates. Addition of lignocellulolytic enzymatic complex from P. ostreatus cultivation to WPC at ensiling decreased WPCS lignin concentration 30 d after ensiling; however, it was not sufficient to improve in situ disappearance of fiber and dry matter.

Effect of Lactobacillus hilgardii, Lactobacillus buchneri, or their combination on the fermentation and nutritive value of sorghum silage and corn silage

The objective of this study was to determine the effect of inoculation with Lactobacillus hilgardii with or without Lactobacillus buchneri on the fermentation, chemical composition, and aerobic stability of sorghum and corn silage after 2 ensiling durations. Sorghum forage was harvested at 27% dry matter (DM; experiment 1), and different corn hybrids were harvested at late (43.8% DM; experiment 2) or normal maturity (34% DM; experiment 3). All harvested forages were chopped and ensiled in quadruplicate in vacuum-sealed nylon-polyethylene bags (40 × 61 cm) for 30 and 90 d after treatment with (1) deionized water (uninoculated) or (2) L. buchneri (1.5 × 10⁵ cfu/g of fresh weight; LB); (3) L. hilgardii (1.5 × 10⁵ cfu/g of fresh weight; LH); or (4) L. buchneri and L. hilgardii (1.5 × 10⁵ cfu/g of fresh weight of each inoculant). Data for each experiment were analyzed separately accounting for the 2 × 2 × 2 factorial treatment arrangement. Inoculating sorghum forage with LB or LH separately increased acetate and 1,2 propanediol concentration, tended to increase DM loss, reduced lactate concentration and the lactate-to-acetate ratio, and increased aerobic stability after 90 but not after 30 d of ensiling. Inoculating late-harvested corn silage with LB or LH separately increased and decreased DM loss, respectively, increased 1,2 propanediol concentration, reduced lactate-to-acetate ratio and yeast counts but did not affect aerobic stability. Inoculating normal-harvested corn silage with LH reduced DM loss and increased 1,2 propanediol concentration and yeast counts; LB reduced lactate concentration, lactate-to-acetate ratio, and total acids. Either inoculant alone increased aerobic stability after 30 or 90 d. The main benefit of combining LB with LH was prevention of increases in DM losses by LH or LB separately. No improvement in aerobic stability resulted from applying LH instead of LB separately or from combining them. Application of LB or LH separately improved aerobic stability of sorghum silage after 90 d and normal-harvested corn silage after 30 or 90 d but did not affect that of late-harvested corn silage.

Effects of Microbial Inoculation and Storage Length on Fermentation Profile and Nutrient Composition of Whole-Plant Sorghum Silage of Different Varieties

This study aimed to assess the effects of a heterofermentative microbial inoculant and storage length on fermentation profile, aerobic stability, and nutrient composition in whole-plant sorghum silage (WPSS) from different varieties. Experiment 1, a completely randomized design with a 2 × 3 factorial treatment arrangement, evaluated microbial inoculation [CON (50 mL distilled water) or LBLD (Lactobacillus plantarum DSM 21762, L. buchneri DSM 12856, and L. diolivorans DSM 32074; 300,000 CFU/g of fresh forage)] and storage length (14, 28, or 56 d) in forage WPSS. The LBLD silage had lower pH compared to CON, and greater concentrations of succinic acid, ethanol, 1,2-propanediol (1,2-PD), 1-propanol, 2,3-butanediol and total acids. After 56 d, lactic acid concentration was greater for CON, while acetic acid and aerobic stability were greater in LBLD silage. Experiment 2, a completely randomized design with a 2 × 3 factorial treatment arrangement, evaluated effects of microbial inoculation (same as experiment 1) and storage length (14, 28, or 56 d) in WPSS of three varieties [forage sorghum (Mojo Seed, OPAL, Hereford, TX), sorghum-sudangrass (Dyna-gro Seed, Fullgraze II, Loveland, CO, United States), or sweet sorghum (MAFES Foundation Seed Stocks, Dale, MS State, MS)]. The LBLD forage sorghum had greater acetic acid and 1,2-PD concentrations at 56 d and 28 d, respectively, but lower concentrations of propionic acid at 56 d and butyric acid at 14 and 28 d. Additionally, WSC concentration was greater for CON than LBLD at 28 d. Furthermore, CON sweet sorghum had greater lactic acid, propionic acid, and butyric acid concentrations. However, greater acetic acid and 1,2-PD were observed for LBLD sweet sorghum. The CON sweet sorghum had greater concentration of WSC and yeast counts. The CON sorghum sudangrass had greater lactic and butyric acid concentrations than LBLD at 14 d, but lower acetic acid and 1,2-PD concentrations at 56 d. Yeast counts were greater for CON than LBLD sorghum sudangrass silage. Overall, results indicate inoculation of WPSS with Lactobacillus plantarum DSM 21762, L. buchneri DSM 12856, and L. diolivorans DSM 32074 improves heterofermentative co-fermentation allowing the accumulation of acetic acid concentration and increasing antifungal capacities and aerobic stability of WPSS.

Meta-analysis of effects of inoculation with Lactobacillus buchneri, with or without other bacteria, on silage fermentation, aerobic stability, and performance of dairy cows

A meta-analysis of 158 peer-reviewed articles was conducted to examine effects of inoculation with Lactobacillus buchneri (LB)-based inoculants (LBB) that did or did not include homolactic or obligate heterolactic bacteria on silage fermentation and aerobic stability. A complementary meta-analysis of 12 articles examined LBB inoculation effects on dairy cow performance. Raw mean differences between inoculant and control treatment means weighted by inverse variance were compared with a hierarchical effects model that included robust variance estimation. Meta-regression and subgrouping analysis were used to identify effects of covariates including forage type, application rate (≤10⁴, 10⁵, 10⁶, or ≥ 10⁷ cfu/g as fed), bacteria type (LB vs. LB plus other bacteria), enzyme inclusion, ensiling duration, and silo type (laboratory or farm scale). Inoculation with LBB increased acetate (62%), 1, 2 propanediol (364%) and propionate (30%) concentration and aerobic stability (73.8%) and reduced lactate concentration (7.2%), yeast counts (7-fold) and mold counts (3-fold). Feeding inoculated silage did not affect milk yield, dry matter intake, and feed efficiency in lactating dairy cows. However, forage type, inoculant composition, and dose effects on silage quality measures were evident. Inoculation with LBB increased aerobic stability of all silages except tropical grasses. Adding obligate homolactic or facultative heterolactic bacteria to LB prevented the small increase in DM losses caused by LB alone. The 10⁵ and 10⁶ cfu/g rates were most effective at minimizing DM losses while aerobic stability was only increased with 10⁵, 10⁶, and ≥ 10⁷ cfu/g rates. Inoculation with LBB increased acetate concentration, reduced yeast counts and improved aerobic stability but did not improve dairy cow performance.

Effects of exogenous α-amylases, glucoamylases, and proteases on ruminal in vitro dry matter and starch digestibility, gas production, and volatile fatty acids of mature dent corn grain

Two separate experiments were carried out to evaluate the effects of incremental doses of 10 exogenous endo-acting α-amylase and exo-acting glucoamylase; 1LAT (bacterial α-amylase), 2AK, 3AC, 4Cs4, 5Trga, 6Afuga, 7Fvga, and 10Tg (fungal α-amylases, glucoamylases, and α-glucosidase), 8Star and 9Syn (fungal amylase-mixtures; experiment 1) and three exogenous proteases; 11P14L, 12P7L, and 13P30L (bacterial proteases; experiment 2) on in vitro dry matter digestibility (IVDMD) and in vitro starch digestibility (IVSD) of mature dent corn grain using a batch culture system. Incremental doses of the exogenous enzymes (0, 0.25, 0.50, 0.75, and 1.00 mg/g of dried substrate) were applied directly to the substrate (0.5 g of ground corn, 4 mm) in sextuplicate (experiment 1) or quadruplicate (experiment 2) within F57 filter bags, which were incubated at 39 °C in buffered rumen fluid for 7 h. Rumen fluid was collected 2-3 h after the morning feeding from three lactating dairy cows and pooled. Cows were consuming a midlactation total mixed ration (TMR; 1.60 Mcal/kg DM and 15.4%; net energy of lactation and crude protein, respectively). Three independent runs were carried out for each experiment. Data were analyzed as a randomized complete block design using run as the blocking factor. Dose was used as a fixed factor while run was considered a random factor. Linear, quadratic, and cubic orthogonal contrasts were also tested. In experiment 1, enzymes 2AK, 3AC, and 10Tg did not increase (P > 0.10) IVDMD and IVSD, whereas 0.25 mg of enzymes 1LAT, 5Trga, and 8Star increased (P < 0.01) IVDMD by 23%, 47%, and 62% and IVSD by 35%, 41%, and 58%, respectively, compared with the control. Enzymes 4Cs4, 6Afuga, 7Fvga, and 9Syn linearly increased IVDMD and IVSD (P < 0.01). Greatest increases in IVDMD (82.9%) and IVSD (85.9%) resulted with 1 mg of 6Afuga compared to control. In experiment 2, the lowest dose of exogenous proteases 11P14L and 12P7L increased (P < 0.01) IVDMD by 98% and 87% and IVSD by 57% and 64%, respectively, whereas the highest dose of 13P30L increased (P = 0.02) IVDMD by 44.8% and IVSD by 30%, relative to the control. In conclusion, IVSD and IVDMD were increased by one α-amylase, certain glucoamylases, and all proteases tested, with the glucoamylase 6Afuga in experiment 1 and the neutral protease 12P7L in experiment 2, increasing IVDMD and IVSD to the greater extents. Future in vivo studies are required to validate these findings before these enzyme additives can be recommended for improving the digestibility of mature dent corn grain.

Effect of kernel processing and particle size of whole-plant corn silage with vitreous endosperm on dairy cow performance

Kernel processing and theoretical length of cut (TLOC) of whole-plant corn silage (WPCS) can affect feed intake, digestibility, and performance of dairy cows. The objective of this study was to evaluate for lactating dairy cows the effects of kernel processing and TLOC of WPCS with vitreous endosperm. The treatments were a pull-type forage harvester without kernel processor set for a 6-mm TLOC (PT6) and a self-propelled forage harvester with kernel processor set for a 6-mm TLOC (SP6), 12-mm TLOC (SP12), and 18-mm TLOC (SP18). Processing scores of the WPCS were 32.1% (PT6), 53.9% (SP6), 49.0% (SP12), and 40.1% (SP18). Twenty-four Holstein cows (139 ± 63 d in milk) were blocked and assigned to six 4 × 4 Latin squares with 24-d periods (18 d of adaptation). Diets were formulated to contain 48.5% WPCS, 15.5% citrus pulp, 15.0% dry ground corn, 9.5% soybean meal, 6.8% low rumen degradability soybean meal, 1.8% calcium soap of palm fatty acids (FA), 1.7% mineral and vitamin mix, and 1% urea (dry matter basis). Nutrient composition of the diets (% of dry matter) was 16.5% crude protein, 28.9% neutral detergent fiber, and 25.4% starch. Three orthogonal contrasts were used to compare treatments: effect of kernel processing (PT6 vs. SP6) and effect of TLOC (particle size; SP6 vs. SP12 and SP12 vs. SP18). Cows fed SP6 produced 1.2 kg/d greater milk yield with no changes in dry matter intake, resulting in greater feed efficiency compared with PT6. Cows fed SP6 also produced more milk protein (+36 g/d), lactose (+61 g/d), and total solids (+94 g/d) than cows fed PT6. The mechanism for increased yield of milk and milk components involved greater kernel fragmentation, starch digestibility, and glucose availability for lactose synthesis by the mammary gland. However, cows fed SP6 had lower chewing time and tended to have greater levels of serum amyloid A compared with PT6. Milk yield was similar for SP6 and SP12, but SP12 cows tended to have less serum amyloid A with greater chewing time. Cows fed SP18 had lower total-tract starch digestibility and tended to have lower plasma glucose and produce less milk compared with cows fed SP12. Compared with PT6, feeding SP6 raised linear odd-chain FA concentration in milk. Similarly, a reduction of these same FA occurred for SP12 compared with SP6. Cows fed SP6 had greater proportion of milk C14:1 and C16:1 compared with PT6 and SP12. Lesser trans C18:1 followed by greater C18:0 concentrations were observed for SP12 and PT6 compared with SP6, which is an indication of more complete biohydrogenation in the rumen. Under the conditions of this study, the use of a self-propelled forage harvester with kernel processing set for a 12-mm TLOC is recommended for WPCS from hybrids with vitreous endosperm.

Effects of processing, moisture, and storage length on the fermentation profile, particle size, and ruminal disappearance of reconstituted corn grain

Our objective was to examine the effects of processing, moisture, and anaerobic storage length of reconstituted corn grain (RCG) on the fermentation profile, geometric mean particle size (GMPS), and ruminal dry matter disappearance (DMD). Dry corn kernels were ground (hammer mill, 5-mm screen) or rolled, then rehydrated to 30%, 35%, or 40% moisture, and stored for 0, 14, 30, 60, 90, 120, or 180 d in laboratory silos. Rolled corn had an increased GMPS compared with ground corn (2.24 and 1.13 mm, respectively, at ensiling). However, there was a trend for an interaction between processing and moisture concentration to affect particle size, with GMPS increasing with increased moisture concentration, especially in ground corn. Longer storage periods also slightly increased GMPS. Processing, moisture, and storage length interacted to affect the fermentation pattern (two- or three-way interactions). Overall, pH decreased, whereas lactic acid, acetic acid, ethanol, and NH3-N increased with storage length. RCG with 30% moisture had less lactic acid than corn with 35% and 40% moisture, indicating that fermentation might have been curtailed and also due to the clostridial fermentation that converts lactic acid to butyric acid. Ensiling reconstituted ground corn with 30% of moisture led to greater concentrations of ethanol and butyric acid, resulting in greater DM loss than grain rehydrated to 35% or 40% of moisture. Ammonia-N and in situ ruminal DMD were highest for reconstituted ground corn with 35% or 40% of moisture, mainly after 60 d of storage. Therefore, longer storage periods and greater moisture contents did not offset the negative effect of greater particle size on the in situ ruminal DMD of rolled RCG. Nonetheless, RCG should be ensiled with more than 30% moisture and stored for at least 2 mo to improve the ruminal DMD and reduce the formation of ethanol and butyric acid.

Graduate Student Literature Review: Current perspectives on whole-plant sorghum silage production and utilization by lactating dairy cows

The purpose of this literature review is to evaluate current research into and understanding of whole-plant sorghum silage production and the effect of feeding whole-plant sorghum silage on lactation performance of dairy cows. Sorghum's drought tolerance, water efficiency, and low cost of production make it an intriguing crop in areas where whole-plant corn silage production may be limited. Currently, urban land encroachment and reduced water availability have increased social and economic pressures on farms to improve crop production efficiency. As these challenges become more prevalent, greater reliance on sorghum can be expected because of its ability to produce high dry matter yields while maintaining nutritive value, even under less-than-ideal growing conditions. Moreover, whole-plant sorghum silage provides both physically effective fiber and energy through fiber and grain fractions. Advancements in sorghum genetics and mechanical processing have the potential to alleviate common challenges associated with whole-plant sorghum silage supplementation, such as increased neutral detergent fiber and decreased neutral detergent fiber digestibility, starch concentration, and starch digestibility. These nutritive challenges must be overcome for whole-plant sorghum silage to be a viable alternative to whole-plant corn silage.

Effect of microbial inoculation and particle size on fermentation profile, aerobic stability, and ruminal in situ starch degradation of high-moisture corn ensiled for a short period

Dairy farmers are often challenged with the need to feed high-moisture corn (HMC) after less than 30 d of fermentation. The objective this study was to assess the effects of microbial inoculation and particle size on fermentation profile, aerobic stability, and ruminal in situ starch degradation of HMC ensiled for a short period. High-moisture corn was harvested, coarsely ground (3,798 ± 40 µm, on average) or finely ground (984 ± 42 µm, on average), then ensiled in quadruplicate vacuum pouches untreated (CON) or with the following treatments: Lactobacillus plantarum CH6072 at 5 × 10⁴ cfu/g and Enterococcus faecium CH212 at 5 × 10⁴ cfu/g of fresh forage (LPEF); or Lactobacillus buchneri LB1819 at 7.5 × 10⁴ cfu/g and Lactococcus lactis O224 at 7.5 × 10⁴ cfu/g (LBLL). Silos were allowed to ferment for 14 or 28 d. Ruminal in situ starch degradation increased when HMC was finely ground. In addition, in situ starch degradation was greater and aerobic stability increased approximately 5-fold with LBLL compared with CON and LPEF. An interaction between microbial inoculation and storage length occurred for lactic acid. At 14 d, concentrations of lactic acid were greatest in LPEF and lowest in LBLL. Lactic acid concentrations increased from 14 to 28 d with CON and LPEF, but decreased with LBLL. At 28 d, concentrations of lactic acid were lower in LBLL compared with CON and LPEF. An interaction between particle size, microbial inoculation, and storage length occurred for acetic acid and ammonia-N. At 14 and 28 d, acetic acid concentrations were greatest in finely ground LBLL followed by coarsely ground LBLL. Ammonia-N concentrations increased across all treatments from 0 to 28 d. At 14 and 28 d, concentrations of ammonia-N were greatest in finely ground LBLL and lowest in coarsely ground CON and coarsely ground LPEF. Results from this study suggest that L. buchneri LB1819 can produce acetic acid in as little as 14 d, and that by 28 d, it has the potential to improve the aerobic stability of HMC. Additionally, results indicate that L. buchneri LB1819 has the potential to improve ruminal degradation of starch by 28 d of storage. Finally, results confirm enhanced fermentation and improved ruminal starch degradation with finely ground HMC by 28 d of storage.

Symposium review: Technologies for improving fiber utilization

The forage lignocellulosic complex is one of the greatest limitations to utilization of the nutrients and energy in fiber. Consequently, several technologies have been developed to increase forage fiber utilization by dairy cows. Physical or mechanical processing techniques reduce forage particle size and gut fill and thereby increase intake. Such techniques increase the surface area for microbial colonization and may increase fiber utilization. Genetic technologies such as brown midrib mutants (BMR) with less lignin have been among the most repeatable and practical strategies to increase fiber utilization. Newer BMR corn hybrids are better yielding than the early hybrids and recent brachytic dwarf BMR sorghum hybrids avoid lodging problems of early hybrids. Several alkalis have been effective at increasing fiber digestibility. Among these, ammoniation has the added benefit of increasing the nitrogen concentration of the forage. However, few of these have been widely adopted due to the cost and the caustic nature of the chemicals. Urea treatment is more benign but requires sufficient urease and moisture for efficacy. Ammonia-fiber expansion technology uses high temperature, moisture, and pressure to degrade lignocellulose to a greater extent than ammoniation alone, but it occurs in reactors and is therefore not currently usable on farms. Biological technologies for increasing fiber utilization such as application of exogenous fibrolytic enzymes, live yeasts, and yeast culture have had equivocal effects on forage fiber digestion in individual studies, but recent meta-analyses indicate that their overall effects are positive. Nonhydrolytic expansin-like proteins act in synergy with fibrolytic enzymes to increase fiber digestion beyond that achieved by the enzyme alone due to their ability to expand cellulose microfibrils allowing greater enzyme penetration of the cell wall matrix. White-rot fungi are perhaps the biological agents with the greatest potential for lignocellulose deconstruction, but they require aerobic conditions and several strains degrade easily digestible carbohydrates. Less ruminant nutrition research has been conducted on brown rot fungi that deconstruct lignocellulose by generating highly destructive hydroxyl radicals via the Fenton reaction. More research is needed to increase the repeatability, efficacy, cost effectiveness, and on-farm applicability of technologies for increasing fiber utilization.

Silage review: Silage feeding management: Silage characteristics and dairy cow feeding behavior

Feeding environment and feed accessibility influence the dairy cow's response to the ration and forage composition. Fiber content, physical form, and fermentability influence feeding behavior, feed intake, and overall cow metabolic and lactational responses to forage. It is possible to vary eating time of lactating dairy cattle by over 1 h/d by changing dietary silage fiber content, digestibility, and particle size. Optimizing silage particle size is important because excessively long particles increase the necessary chewing to swallow a bolus of feed, thereby increasing eating time. Under competitive feeding situations, excessively coarse or lower fiber digestibility silages may limit DMI of lactating dairy cows due to eating time requirements that exceed available time at the feed bunk. Additionally, greater silage particle size, especially the particles retained on the 19-mm sieve using the Penn State Particle Separator, are most likely to be sorted. Silage starch content and fermentability may influence ruminal propionate production and thereby exert substantial control over meal patterns and feed consumption. Compared with silage fiber characteristics, relatively little research has assessed how silage starch content and fermentability interact with the feeding environment to influence dairy cow feeding behavior. Finally, voluminous literature exists on the potential effects that silage fermentation end products have on feeding behavior and feed intake. However, the specific mechanisms of how these end products influence behavior and intake are poorly understood in some cases. The compounds shown to have the greatest effect on feeding behavior are lactate, acetate, propionate, butyrate, ammonia-N, and amines. Any limitation in the feeding environment will likely accentuate the negative response to poor silage fermentation. In the future, to optimize feeding behavior and dry matter intake of silage-based diets fed to dairy cattle, we will need to consider the chemical and physical properties of silage, end products of silage fermentation, and the social and physical components of the feeding environment.

Effect of ensiling time on fermentation profile and ruminal in vitro starch digestibility in rehydrated corn with or without varied concentrations of wet brewers grains

The objective of this study was to evaluate the effect of rehydrating and ensiling dry ground corn (DGC) with varying concentrations of wet brewers grain (WBG) on fermentation profile and ruminal in vitro starch digestibility (ivSD; 7-h incubations on dried and 4-mm ground samples). Samples of DGC and WBG were weighed separately and mixed into 100% WBG (WBG); mixture of DGC and WBG targeting 60 (RC60), 65 (RC65), or 70% (RC70) of dry matter (DM); and DGC rehydrated with distilled water targeting for 70% of DM (REH). Samples were ensiled in vacuum-sealed bags and allowed to ferment for 0, 1, 3, 7, 14, and 28 d. The experiment consisted of 30 treatments (5 mixtures of DGC and WGB × 6 ensiling time points) and 120 mini-silos (4 silos per treatment). All samples were analyzed for fermentation profile and water-soluble carbohydrates. Except for WBG, samples from 0 and 28 d were analyzed for ivSD. Content of DM was greater for REH (70.0%), followed by RC70 (69.2%), RC65 (63.9%), RC60 (58.4%), and WBG (17.5%) on d 0, with a slight decrease (1 to 2 percentage units) observed for all treatments until 28 d. Measurements of pH were highest for REH (6.19) and lowest for WBG (4.68) on 0 d, but all other treatments were lower than WBG on 14 and 28 d (3.83 vs. 4.14, on average). Except for WBG, all treatments had a gradual increase in lactic acid concentration from 0 to 28 d. In contrast, butyric acid gradually increased from 0 (0.25%) to 28 d (2.16% of DM) in WBG but not the other treatments. Fermentation patterns were related to water-soluble carbohydrates concentration, which was greater for all treatments except WBG from 0 (1.41% on average vs. 0.38% of DM, respectively) to 28 d (0.37% on average vs. 0.19% of DM, respectively). Except for RC60, greater ivSD was observed for all treatments on 28 than 0 d, but magnitude of the difference was greater for REH and RC70 (14.5 percentage units on average). Rehydration and ensiling of DGC with WBG resulted in adequate fermentation and enhanced starch digestibility.

Effect of adding clay with or without a Saccharomyces cerevisiae fermentation product on the health and performance of lactating dairy cows challenged with dietary aflatoxin B1

The study was conducted to examine the effect of supplementing bentonite clay with or without a Saccharomyces cerevisiae fermentation product (SCFP; 19 g of NutriTek + 16 g of MetaShield, both from Diamond V, Cedar Rapids, IA) on the performance and health of dairy cows challenged with aflatoxin B₁ (AFB₁). Twenty-four lactating Holstein cows (64 ± 11 d in milk) were stratified by parity and milk production and randomly assigned to 1 of 4 treatment sequences. The experiment had a balanced 4 × 4 Latin square design with 6 replicate squares, four 33-d periods, and a 5-d washout interval between periods. Cows were fed a total mixed ration containing 36.1% corn silage, 8.3% alfalfa hay, and 55.6% concentrate (dry matter basis). Treatments were (1) control (no additives), (2) toxin (T; 1,725 µg of AFB₁/head per day), (3) T + clay (CL; 200 g/head per day; top-dressed), and (4) CL+SCFP (CL+SCFP; 35 g/head per day; top-dressed). Cows were adapted to diets from d 1 to 25 (predosing period) and then orally dosed with AFB₁ from d 26 to 30 (dosing period), and AFB₁ was withdrawn from d 31 to 33 (withdrawal period). Milk samples were collected twice daily from d 21 to 33, and plasma was sampled on d 25 and 30 before the morning feeding. Transfer of ingested AFB₁ into milk aflatoxin M₁ (AFM₁) was greater in T than in CL or CL+SCFP (1.65 vs. 1.01 and 0.94%, respectively) from d 26 to 30. The CL and CL+SCFP treatments reduced milk AFM₁ concentration compared with T (0.45 and 0.40 vs. 0.75 µg/kg, respectively), and, unlike T, both CL and CL+SCFP lowered AFM₁ concentrations below the US Food and Drug Administration action level (0.5 µg/kg). Milk yield tended to be greater during the dosing period in cows fed CL+SCFP compared with T (39.7 vs. 37.7 kg/d). Compared with that for T, plasma glutamic oxaloacetic transaminase concentration, indicative of aflatoxicosis and liver damage, was reduced by CL (85.9 vs. 95.2 U/L) and numerically reduced by CL+SCFP (87.9 vs. 95.2 U/L). Dietary CL and CL+SCFP reduced transfer of dietary AFB₁ to milk and milk AFM₁ concentration. Only CL prevented the increase in glutamic oxaloacetic transaminase concentration, and only CL+SCFP prevented the decrease in milk yield caused by AFB₁ ingestion.

Effect of ensiling time and exogenous protease addition to whole-plant corn silage of various hybrids, maturities, and chop lengths on nitrogen fractions and ruminal in vitro starch digestibility

The objective of this study was to evaluate the effects of ensiling time and exogenous protease addition on soluble CP (% of CP), ammonia-N (% of N), and ruminal in vitro starch digestibility (ivSD) of whole-plant corn silage (WPCS) from 3 hybrids, 2 maturities, and 2 chop lengths. Samples from 3 nonisogenic hybrids [brown midrib containing the bm3 gene mutation (BM3), dual-purpose (DP), or floury-leafy (LFY)] at 2 harvest maturities [2/3 kernel milk line (early) or 7d later (late)] with 2 theoretical lengths of cut settings (0.64 or 1.95cm) on a forage harvester were collected at harvest, treated with or without exogenous protease, and ensiled in triplicate in vacuum heat-sealed plastic bags for 0, 30, 60, 120, and 240d. Thus, the experiment consisted of 120 treatments (3 hybrids × 2 maturities × 2 chop lengths × 2 protease treatments × 5 time points) and 360 mini-silos (3 replications per treatment). Vitreousness, measured by dissection on unfermented kernels on the day of harvest, averaged 66.8, 65.0, and 59.0% for BM3, DP, and LFY, respectively. A protease × maturity interaction was observed with protease increasing ivSD in late but not early maturity. Ensiling time × hybrid interactions were observed for ammonia-N and soluble CP concentrations with greater values for FLY than other hybrids only after 120d of ensiling. Ensiling time × hybrid or protease × hybrid interactions were not observed for ivSD. Measurements of ivSD were greatest for FLY and lowest for BM3. Length of the ensiling period did not attenuate negative effects of kernel vitreousness or maturity on ivSD in WPCS. Results suggest that the dosage of exogenous protease addition used in the present study may reduce but not overcome the negative effects of maturity on ivSD in WPCS. No interactions between chop length and ensiling time or exogenous protease addition were observed for ivSD.

Effects of corn-based diet starch content and corn particle size on lactation performance, digestibility, and bacterial protein flow in dairy cows

An experiment was conducted to determine the effects of dietary starch content in corn-based diets and corn particle size on lactation performance, nutrient digestibility, and bacterial protein flow in dairy cows using the omasal and reticular sampling technique. Eight ruminally cannulated lactating multiparous Holstein cows were used in a replicated 4×4 Latin square design with a 2×2 factorial arrangement of treatments. Treatments were fine (FG; mean particle size=552µm) and coarse (CG; 1,270µm) ground dry shelled corn in normal- (NS) and reduced- (RS) starch diets fed as total mixed rations. The NS and RS rations contained 27 and 18% starch (dry matter basis), respectively, and were formulated by partially replacing corn with soy hull pellets. Mean dry matter intake was unaffected by treatment (23.2kg/d). Cows fed NS diets produced 1.9kg/d more milk and 0.06kg/d more milk protein compared with cows fed RS diets. Cows fed NSFG and RSCG diets produced more fat-corrected milk than did cows fed NSCG and RSFG diets. Milk urea concentration was decreased for cows fed NS diets (12.4mg/dL) compared with RS diets (13.5mg/dL). Ruminal digestibility of neutral detergent fiber (NDF; % of NDF intake) determined by the omasal sampling technique was increased in cows fed RS diets compared with NS diets (43.4 vs. 34.9%), and total-tract digestibility of NDF (% of NDF intake) was increased in cows fed RS diets compared with those fed NS diets (50.1 vs. 43.1%). Ruminal digestibility of starch (% of starch intake) determined by the omasal sampling technique was greater in cows fed NS diets compared with those fed RS diets (85.6 vs. 81.6%). Total-tract starch digestion was increased in cows fed RS diets compared with those fed NS diets (96.9 vs. 94.6%) and in cows fed FG diets compared with those fed CG diets (98.0 vs. 93.5%). Bacterial protein flow was unaffected by treatment. The omasal and reticular sampling techniques resulted in similar treatment effects for nutrient flow and digestibility, although nutrient flow was lower and nutrient digestibility was greater in cows when sampled by the omasal technique compared with the reticular technique. Cows fed FG diets had greater ruminal propionate, lower acetate:propionate ratio, and lower pH. Feeding NS diets increased milk and protein yields and feeding finely ground corn increased ruminal propionate concentration.

Effect of feed restriction on reproductive and metabolic hormones in dairy cows

The objective of this trial was to evaluate the effects of feed restriction (FR) on serum glucose, nonesterified fatty acids, progesterone (P4), insulin, and milk production in dairy cows. Eight multiparous Holstein cows, 114 ± 14 d pregnant and 685 ± 39 kg of body weight, were randomly assigned to a replicated 4 × 4 Latin square design with 14-d periods. During the first 8 d of each period, cows in all treatments were fed for ad libitum feed intake. Beginning on d 9 of each period, cows received 1 of 4 treatments: ad libitum (AL), 25% feed restriction (25 FR), 50% feed restriction (50 FR), and 50% of TMR replaced with wheat straw (50 ST). Daily feed allowance was divided into 3 equal portions allocated every 8h with jugular blood samples collected immediately before each feeding through d 14. In addition, on d 12 of each period, blood samples were collected before and at 60, 120, 180, 240, 300, 360, 420, and 480 min after morning feeding. The conventional total mixed ration and total mixed ration with straw averaged 15.1 and 10.8%, 32.1 and 50.5%, and 26.8 and 17.0% for concentrations of crude protein, neutral detergent fiber, and starch, respectively. Cows that were feed and energy restricted had reduced dry matter intake, net energy for lactation intake, circulating glucose concentrations, and milk production, but greater body weight and body condition score losses than AL cows. Circulating concentrations of insulin were lower for cows fed 50 FR (8.27 μIU/mL) and 50 ST (6.24 μIU/mL) compared with cows fed AL (16.65 μIU/mL) and 25 FR (11.16 μIU/mL). Furthermore, the greatest plasma nonesterified fatty acids concentration was observed for 50 ST (647.7 μ Eq/L), followed by 50 FR (357.5 μEq/L), 25 FR (225.3 μEq/L), and AL (156.3 μEq/L). In addition, serum P4 concentration was lower for cows fed AL than cows fed 50 ST and 25 FR. Thus, FR reduced circulating glucose and insulin but increased P4 concentration, changes that may be positive in reproductive management programs.