High-retention membrane bioreactors for sugarcane vinasse treatment: Opportunities for environmental impact reduction and wastewater valorization.

Ethanol production has increased over the years, and Brazil ranking second in the world using sugarcane as the main raw material. However, 10-15 L of vinasse are generated per liter of ethanol produced. Besides large volumes, this wastewater has high polluting potential due to its low pH and high concentrations of organic matter and nutrients. Given the high biodegradability of the organic matter, the treatment of this effluent by anaerobic digestion and membrane separation processes results in the generation of high value-added byproducts such as volatile fatty acids (VFAs), biohydrogen and biogas. Membrane bioreactors have been widely evaluated due to the high efficiency achieved in vinasse treatment. In recent years, high retention membrane bioreactors, in which high retention membranes (nanofiltration, reverse osmosis, forward osmosis and membrane distillation) are combined with biological processes, have gained increasing attention. This paper presents a critical review focused on high retention membrane bioreactors and the challenges associated with the proposed configurations. For nanofiltration membrane bioreactor (NF-MBR), the main drawback is the higher fouling propensity due to the hydraulic driving force. Nonetheless, the development of membranes with high permeability and anti-fouling properties is uprising. Regarding osmotic membrane bioreactor (OMBR), special attention is needed for the selection of a proper draw solution, which desirably should be low cost, have high osmolality, reduce reverse salt flux, and can be easily reconcentrated. Membrane distillation bioreactor (MDBR) also exhibit some shortcomings, with emphasis on energy demand, that can be solved with the use of low-grade and residual heat, or renewable energies. Among the configurations, MDBR seems to be more advantageous for sugarcane vinasse treatment due to the lower energy consumption provided by the use of waste heat from the effluent, and due to the VFAs recovery, which has high added value.

Sugarcane vinasse as organo-mineral fertilizers feedstock: Opportunities and environmental risks.

Fertigation using sugarcane vinasse is expected in the sugar and alcohol industries; however, its indiscriminate practice can trigger soil salinization and contamination of water sources. This review article appraises the vinasse use as a precursor material in producing organo-mineral fertilizers. Vinasse use could be an alternative for the increased demand for organo-mineral fertilizers. In that case, the vinasse reuse would be maintained but through controlled practices and lower environmental impact. The state-of-art points to possible advantages associated with the vinasse conversion into organo-mineral fertilizers, such as ease of transport and handling, low variability in its composition, and lower risks of soil and water resources contamination. It has been summarized and critically discussed the past ten years (2011-2021, total number papers revised: 175) of research data about vinasse composition, along with the limitations to be overcome in the near future to enable the application of organo-mineral fertilizers. Possible nutrients supplementation beyond those already present in vinasse composition would depend on the crop requirement, and the impact on the soil biota and integrity should be better understood. The aspects discussed along the manuscript would be aligned with circular economy principles, converting a residue (vinasse) into a potential resource for agricultural activities, including sugar and alcohol industries. After all, although promising, obtaining organo-mineral fertilizers from vinasse must be empirically validated and its feasibility proven by comparative studies between fertigation and the use of organo-mineral fertilizers.

Efficacy of plants extracts from the Cerrado against adult female of Dermacentor nitens (Acari: Ixodidae).

Dermacentor nitens tick is commonly found in the equine auditory canal, where it causes economic losses due to its direct damage, causing blood spoliation, stress, transmission of pathogens, and predisposition to myasis and secondary bacterial infection in its hosts. In this study we evaluated the effect of ethanolic extracts of Cerrado plants on biological parameters of engorged females of D. nitens. Ethanolic extracts were prepared from the leaves of Schinopsis brasiliensis, Piptadenia viridiflora, Ximenia americana, and Serjania lethalis at 25-150 mg mL-1. Groups of 10 engorged adult females were treated with these extracts and compared with a control containing distilled water and another control with organophosphate, using five replicates for each group. Compared with the control with water, S. lethalis and X. americana extracts at 100 and 150 mg mL-1 significantly inhibited the posture ability. Differently, extracts of S. brasiliensis and P. viridiflora were the most effective in inhibiting larval hatching. Extracts of X. americana and P. viridiflora showed effective inhibition of reproductive parameters of the tick, presenting dose-dependent effect with IC90 78.86 and 78.94 mg mL-1, respectively. Theses effective extracts contained low condensed tannin levels and their HPLC chromatograms revealed the presence of flavonoids. The efficacies of P. viridiflora and X. americana extracts were higher than 90% indicating that these extracts are promising as alternative agents for D. nitens control.

Short communication: Substituting dry distillers grains with solubles and rumen-protected amino acids for soybean meal in late-lactation cows' diets based on corn silage or ryegrass silage.

Excess protein in dairy cattle diets increases production costs and contributes to environmental pollution. The objective of the present study was to evaluate the effect of feeding dry distillers grains with solubles (DDGS) supplemented with rumen-protected Lys and Met in place of solvent-extracted soybean meal on the performance of late-lactation cows. Two experiments were carried out, with each using 24 late-lactating dairy cows distributed among 4 pens. In trial 1, corn silage was the main forage source. Control (HP1) total mixed ration (TMR) contained 16.3% crude protein (CP) with soybean meal as the main protein source. Treatment TMR (LP1) had 13.7% CP when soybean meal was replaced with DDGS and rumen-protected Lys and Met. Forage in trial 2 was ryegrass silage; control TMR (HP2; 15.4% CP) contained soybean meal and rumen-protected Met, whereas treatment TMR (LP2; 13.8% CP) contained DDGS and rumen-protected Lys and Met. Trials were analyzed as crossover design using the MIXED procedure of SAS (SAS Institute Inc., Cary NC) with cow as sampling unit and pen as the experimental unit. Treatments were similar in dry matter intake (21.0 and 20.4 kg/cow per day for HP1 and LP1, respectively) and milk yield (20.7 and 20.5 kg/cow per day for HP1 and LP1, respectively) during trial 1. Milk composition was similar between treatments, averaging 4.22, 3.73, 4.54, and 9.15, respectively, for fat, protein, lactose, and solids nonfat. Milk urea nitrogen decreased from 17.2 mg/dL for HP1 to 9.93 mg/dL for LP1. In trial 2, no significant differences were observed for dry matter intake (21.4 and 20.9 kg/cow per day for HP2 and LP2, respectively), milk yield (28.1 and 26.6 kg/d for HP2 and LP2, respectively), fat yield (0.99 vs. 0.92 kg/d for HP2 and LP2, respectively), protein yield (0.94 vs. 0.86 kg/d for HP2 and LP2, respectively) and lactose yield (1.37 vs. 1.28 for HP2 and LP2, respectively). Milk urea nitrogen decreased from 9.88 mg/dL with HP2 to 6.39 mg/dL with the LP2 treatment. Milk N efficiency tended to be higher for LP treatments in trial 1, but not in trial 2. Low milk urea N suggested nitrogen losses to the environment may be lower when cows were fed diets based on DDGS in both trials. The studies indicated that DDGS with rumen-protected Lys and Met could substitute solvent-extracted soybean meal in low-protein corn silage- and ryegrass silage-based diets for late-lactation dairy cows averaging 20.6 or 27.4 kg of milk/d, respectively.

Antimutagenic action of the triterpene betulinic acid isolated from Scoparia dulcis (Scrophulariaceae).

The mutagenic and antimutagenic activities of triterpene betulinic acid {3b-3-hydroxy-lup-20(29)-en-28-oic} isolated from the roots of Scoparia dulcis (Scrophulariaceae) were analyzed using the somatic mutation and recombination test (SMART) in the wings of Drosophila melanogaster. The mutagenic potential of betulinic acid was evaluated at 3 different concentrations (1.64, 3.28, and 6.57 mM). Antimutagenic activity evaluation was performed by co-treatment trials in which the flies received betulinic acid at 3 different concentrations in addition to 10 mM pro-mutagenic urethane. The results demonstrated that betulinic acid was not capable of causing DNA damage. However, the frequency of small single spots, large spots, and twin spots was significantly reduced. In the high bioactivation cross, betulinic acid was significantly active and exerted enhanced antimutagenic activity, possibly as a desmutagen.

Effect of condensed corn distillers solubles concentration on lactation performance of Holstein cows.

Forty-eight Holstein cows (32 multiparous and 16 primiparous) in mid to late lactation averaging 219±71 days in milk and 30.5±6.6 kg/d of 3.5% fat-corrected milk were used in a 56-d completely randomized design experiment to evaluate condensed corn distillers solubles (CCDS) inclusion in high-fiber total mixed rations (TMR). Inclusion rates evaluated were 0, 6.6, 13.2, and 19.8% CCDS as a percentage of dry matter (DM). Distiller solubles substituted for soybean meal, corn grain, and whole cottonseed such that diets were similar in protein (16.6%) and fat (4.50%). Water was added to 0, 6.6, and 13.2% CCDS treatments so that final TMR DM concentrations (47.8%) were similar across diets. The forage portion of the diet was kept constant at 19.6% annual ryegrass hay and 26.0% sorghum baleage. Diet in vitro true digestibility tended to increase as CCDS addition increased, but neutral detergent fiber digestibility trended lower in CCDS diets. Percent P (0.39, 0.55, 0.69, and 0.73%) and S (0.32, 0.35, 0.39, and 0.42%) in TMR increased as CCDS concentration increased. Milk yield (23.5, 24.7, 25.5, and 24.8 kg/d of 3.5% fat-corrected milk) was similar for control and CCDS diets. Milk fat (3.88, 3.73, 3.78, and 3.68%), protein (3.28, 3.27, 3.31, and 3.31%), and lactose (4.61, 4.66, 4.69, and 4.77) percentages were similar across diets. Milk urea nitrogen (16.60, 15.58, 15.43, and 14.75 mg/dL) declined with increasing CCDS addition. Animal activity, body weight, body condition scores, and locomotion scores were not influenced by CCDS. Day 28 poststudy locomotion scores were similar across diets. Ruminal acetate concentrations did not differ among diets, but propionate and butyrate concentrations were elevated in rumen fluid of cows receiving 19.6% CCDS. Although rumen fluid pH values were similar (6.5, 6.4, 6.3, and 6.2), the two highest CCDS diets exhibited depressed acetate:propionate ratios relative to controls. The results from this study indicate that CCDS may be included in high-fiber TMR for lactating dairy cows at up to nearly 20% of diet DM; however, caution is recommended because high CCDS P concentrations may create Ca:P imbalances and excess P may be introduced into the environment.

Protective effects of the antileishmanial extract of Tephrosia cinerea (L.) Pers. (Fabaceae) against cyclophosphamide-induced damage.

Tephrosia cinerea L. (Pers.) is a tropical species that exhibits antileishmanial activity in Leishmania amazonensis promastigote cultures and is commonly used to treat infections, inflammations, ulcers, nervous conditions, and diarrhea. However, no studies have investigated its effects on genetic material. Therefore, we evaluated the genotoxic potential, antigenotoxic potential, and cytotoxic effects of hydroalcoholic extracts of T. cinerea leaves. In an in vitro genotoxicity study, human peripheral blood leukocytes were treated for 3, 24 (comet assay), or 48 h (cell death assay) with 22, 44, or 88 µg/mL plant extract. In the in vivo assay, Swiss mice were treated with 500, 1000, or 2000 mg extract/kg body weight by intraperitoneal injection and were evaluated 24 h later. Antigenotoxicity was investigated in pre- and post-treatment assays in which the animals received the plant extract (2000 mg/kg) 24 h before or after receiving cyclophosphamide (50 mg/kg), respectively. The extract had no genotoxic effects in the in vitro or in vivo assays. However, the extract reduced apoptotic cell death and induced necrotic cell death at concentrations that presented leishmanicidal activity in vitro. The extract also had an antigenotoxic effect, reducing the levels of genomic damage that were caused by cyclophosphamide in Swiss mice by more than 80%.

Evaluation of genotoxic and cytotoxic effects of antileishmanial extract from Julocroton triqueter (Euphorbiaceae).

Julocroton triqueter extracts have antileishmanial activity; however, the effect on genetic stability has not been studied. We evaluated genotoxic and cell death induction potential (in vitro and in vivo) of J. triqueter var. triqueter hydroalcoholic extracts, as well as their antigenotoxic potential in vivo. The in vitro genotoxic studies were performed using human leukocytes at four different concentrations. For the in vivo tests, Swiss mice were treated with 125, 250 or 500 mg/kg of extract injected intraperitoneally. Antigenotoxic effects of the extract were measured before and after cyclophosphamide treatment. An absence of genotoxic effects was observed both in vitro and in vivo. In the antigenotoxic studies, no significant difference was observed between the treatments and the positive control, indicating that the extracts did not protect against damage caused by cyclophosphamide. Hydroalcoholic extracts of J. triqueter did not provoke DNA damage at concentrations and doses normally used for antileishmanial treatment; however, they reduced apoptotic cell death and induced necrotic cell death.

Forage conservation efficiency and lactation response to bahiagrass conserved as barn-stored hay, outdoor-stored hay, or baleage.

A study was conducted to determine the effect of conserving bahiagrass as outdoor-stored hay (OSH), barn-stored hay (BSH), or baleage (BAL) on storage losses and lactation performance by Holstein cows. For baleage production, bahiagrass forage was cut and allowed to dry for 20 h in windrows, baled (1.2 × 1.4 m), and individually wrapped with white stretch film. Forage cut on the same day was dried to hay stage, baled (1.2 × 1.6 m round bales), and stored either outdoors (OSH) or in an enclosed hay barn (BSH). Bales were core sampled and weighed at harvest and again following a 6-mo storage period. At the end of the storage period, 30 multiparous mid-lactation Holstein cows [39.2 ± 5.6 kg of 3.5% fat-corrected milk and 142 ± 27 d in milk (DIM)] were stratified according to milk yield and DIM and randomly assigned to 1 of the 3 forage conservation treatments. Cows were trained to Calan feeding gates and were offered a common partial mixed ration in a 10-d covariate period followed by a 42-d treatment feeding period. Forage dry matter losses were highest for OSH, but were similar between BSH and baleage. Conservation method had little effect on poststorage crude protein levels, but acid detergent fiber and neutral detergent fiber concentrations were higher in OSH than in either BSH or BAL, which resulted in a 12.8% depression in net energy for OSH compared with the other treatments. Dry matter intake (20.5 vs. 22.1 kg/d) and milk yield (28.2 vs. 30.2 kg/d) tended to be lower for OSH than for BSH. Lactation performance was similar between BSH and BAL: 29.6 versus 28.7 kg/d of fat-corrected milk, respectively. No differences in milk composition, feed efficiency, body weight, or body condition score change related to conservation system were observed. In this study, dry matter losses and lactation performance from bahiagrass conserved as baleage were similar to that of similar forage stored indoors as hay, whereas hay stored outside resulted in less satisfactory forage quality.

Influence of calcium and phosphorus feeding on markers of bone metabolism in transition cows.

A study was carried out to verify the effect of Ca and P levels on production, digestibility, and serum bone metabolism biomarkers in dairy cows. Fifty-two nonlactating multiparous cows (>or=3 lactations) were confined in a free-stall barn approximately 20 d before calving. A standard close-up diet was fed to cows once daily until d 2 postpartum. Cows were randomly assigned to 1 of 4 dietary treatments arranged in a 2 x 2 factorial approach averaging 0.64% Ca for high Ca (HCa), 0.46% Ca for low Ca (LCa), 0.47% P for high P (HP), and 0.38% P for low P (LP) on a dry matter basis. Experimental diets were fed twice daily from 3 d in milk (DIM) until 31 DIM. Intake and milk yield were recorded daily. Milk samples were collected on d 28, 29, and 30 postpartum for components analyses. Blood samples were drawn 10 d before expected calving, at calving, and at 15 and 30 DIM for serum analyses of osteocalcin, a biomarker of bone accretion, and pyridinoline, a biomarker of bone resorption. Total fecal collection was conducted when cows in a block averaged 20 DIM. Intake and production traits were not significantly affected by any of the dietary treatments. Cows averaged nearly 21 kg/d dry matter intake and 44 kg/d milk yield from 6 to 31 DIM. There were no significant differences across treatments in body weight or body condition score loss. Phosphorus intake, P fecal output, P digestibility, and P apparent absorption were affected by dietary P content. Calcium intake was higher with HCa, but Ca fecal output, digestibility, and apparent absorption showed an interaction between dietary Ca and dietary P. Calcium fecal output was 100.6 g/d for cows fed HCaHP, intermediate for cows on the HCaLP diet (89 g/d), and similar among cows fed the 2 LCa diets (70 g/d with LCaHP and 75 with LCaLP). There was no significant effect of Ca or P on osteocalcin measurements. Pyridinoline concentrations were affected by dietary Ca levels and tended to have a significant dietary Ca x dietary P interaction. Phosphorus apparent digestibility occurred independently of dietary Ca levels. Results of this study suggest that more bone was mobilized in cows fed LCa diets, but excess dietary P caused greater and prolonged bone mobilization regardless of dietary Ca content.

Effect of scraping frequency in a freestall barn on volatile nitrogen loss from dairy manure.

The objective of this investigation was to evaluate the effect of scraping frequency (2x vs. 6x daily) on N volatilization from manure on the floor of a dairy free-stall barn. Three trials (crossover design) were conducted in the summers of 2001 and 2002, and in the winter of 2003. Nitrogen volatilization was estimated from the change in the N:P ratio in excreta at the time of excretion to the time when manure was scraped from the barn. Total N loss was considered a maximum estimate of NH3-N loss, because small amounts of nonammonia N may be volatilized. Nitrogen was determined after manure subsamples were lyophilized; P content was measured by direct current emission spectroscopy of ashed subsamples of manure. Lactating dairy cows were fed high-protein (18.5 to 19.3% crude protein), alfalfa-based diets. Average milk yield was 31.9 (SD = 7.4) kg/d. Scraping frequency had no effect on N loss in summer 2001. An average of 41% of excreted N, or 238 +/- 19.0 g of N/d per cow, was volatilized. For the trial in summer 2002, nitrogen volatilization was reduced from 50% of the excreted N with 2x to 46.7% with 6x, equivalent to 265 and 248 g of N lost/d per cow, respectively. Scraping had no effect on N volatilization during the winter trial. An average of 17.7% of excreted N was volatilized during the winter, equivalent to 109 +/- 11.0 g of N lost/d per cow. Scraping frequency of manure had little or no effect on N loss from manure in a freestall barn. Nitrogen loss during the winter was less than half of the loss during the summer.

Comparison of conventional linted cottonseed and mechanically delinted cottonseed in diets for dairy cows.

Performance of lactating dairy cows fed diets containing either mechanically delinted whole cottonseed (DWCS; 3.7% lint) or linted whole cottonseed (LWCS; 11.7% lint) was measured. Forty primiparous (86 +/- 39 d in milk) and 40 multiparous (88 +/- 30 d in milk) cows were fed a total mixed ration containing 13% (dry matter basis) DWCS or LWCS in two blocks of 112 d (n = 53 and 27, respectively). Other total mixed ration ingredients (dry matter basis) were corn silage (28.1%), alfalfa silage (23%), high moisture shelled corn (27.8%), soybean meal (1.8%), expeller soybean meal (1.8%), blood meal (2%), and mineral-vitamin supplements (2.5%). Dry matter intake and milk yield were measured daily and milk composition every other week. Fecal grab samples were taken during wk 3 and 13 of each block to estimate excretion of intact whole cottonseeds. Milk yield, 3.5% fat-corrected milk, energy-corrected milk, milk composition and dry matter intake were not affected by whole cottonseed source. Body condition score tended to increase more with DWCS (0.22 vs. 0.11) for primiparous cows, although this was not reflected in body weight change. Dry matter digestibilities, based on indigestible ADF, were 63.5 and 64.8% for the DWCS and LWCS diets. It was calculated that 2.5 and 1.5% of the consumed seeds were excreted as whole cottonseeds in feces with the DWCS and LWCS diets, respectively. Although statistically significant, treatment differences in the proportion of intact seeds in the fecal DM would have little nutritional consequence. Mechanically delinted WCS performed as well as LWCS for all of the cow performance and milk composition variables measured.

Reproductive performance of dairy cows fed two concentrations of phosphorus.

The objective of this study was to determine the effect of dietary P concentrations of 0.37 (recommended) or 0.57% (excess; dry matter basis) on reproductive performance. At calving, Holstein cows were randomly assigned to 1 of 2 dietary treatments (n = 134 for 0.37% P and n = 133 for 0.57% P). Cows were fitted with a radiotelemetric transmitter (50 d in milk [DIM]) to record mounting activity during estrus and bred to natural estrus from 50 to 100 DIM, then to synchronized estrus (Ovsynch protocol) after 100 DIM. Weekly ultrasonography was performed from 50 DIM until pregnancy was diagnosed (-30 d after artificial insemination). Pregnancy was confirmed approximately 60 d after artificial insemination (artificial insemination). Weekly blood samples were analyzed for progesterone concentrations. Days to first increase (>1 ng/ml) in progesterone, days to first estrus detected by radiotelemetry, days to first service detected by herd personnel, and conception rate at first service did not differ between the recommended and excess P groups, respectively. Similarly, conception rate at 30 d, days open, pregnancies lost from 30 to 60 d, multiple ovulation rate, and the incidence of anovulatory condition at 71 DIM did not differ between these groups. The mean duration of estrus was 8.7 +/- 0.5 and 8.7 +/- 0.7 h, and the average number of mounts per estrus was 7.4 +/- 0.5 and 7.8 +/- 0.5 for a total mounting time during estrus of 25.8 +/- 1.8 and 24.5 +/- 1.6 s for cows fed the recommended and excess P diet, respectively. Phosphorus treatment had no detectable effect on reproductive performance.

Effect of dietary phosphorus on performance of lactating dairy cows: milk production and cow health.

The objective of this study was to measure cow response to feeding of two dietary concentrations of P, one of which was close to recent National Research Council requirements, and the other of which was well in excess of the requirement. Diets containing 0.37 or 0.57% P (dry basis) were fed to Holstein cows for the first 165 d of lactation, and occasionally longer until cows were confirmed pregnant approximately 60 d after insemination. At calving, cows were randomly assigned to experimental diets. The number of cows completing a minimum of 165 d of lactation was 123 for the 0.37 and 124 for the 0.57% P groups. Cows were housed in a stanchion barn and fed one of two transition diets, each formulated to contain one of the P treatments for the first 3 wk of lactation, and then cows were moved to a free-stall barn where the experimental diets were group fed. Milk production, milk fat, and milk protein averaged 35.1 kg/d, 3.92%, and 2.90% for the 0.37% P diet, and 34.9 kg/d, 3.98%, and 2.91% for the 0.57% P diet. None of these measures were different between treatments. Blood serum P concentrations on d 50 and 100 of lactation averaged 6.1 and 6.2 mg/dL for the 0.37% P diet, and 6.8 and 6.9 mg/dL for the 0.57% P diet. No treatment differences were detected in milk production, cow health, or body condition score.

Produçäo de leite de vacas alimentadas com alta proporçäo de forragem em dietas / Feeding high forage diets to lactating dairy cows

Vinte e duas vacas primíparas e 26 multíparas da raça Holandesa foram distribuídas em três tratamentos em um delineamento inteiramente ao acaso. As dietas testadas consistiram de duas proporçöes forragem:concentrado, 55:45 (RCS) e 75:25 (RCSH), para silagem de milho comum, e 75:25 (BMR) para outra dieta baseada no híbrido bm3. Näo houve interaçäo entre tratamentos e ordem de lactaçäo. A proporçäo silagem de alfafa:silagem de milho na porçäo forrageira da dieta foi de 47,7:53,3. A ingestäo (kg/dia) de matéria seca e de proteína bruta foi superior para BMR e RCS (19,5 e 19,5; 3,41 e 3,42, respectivamente) em relaçäo à ingestäo para RCSH (17,6 e 3,14), enquanto que a de fibra em detergente neutro foi maior para BMR (6,61) e menor para RCSH e RCS (6,08 e 5,40, respectivamente). O consumo de fibra em detergente ácido (kg/dia) foi maior para BMR e RCSH (4,88 e 4,73) e menor para RCS (4,02). A produçäo de leite foi superior para o tratamento com maior proporçäo de concentrados (35,7kg/vaca/dia), seguida pelo tratamento BMR (34,1kg/vaca/dia) e finalmente por RCSH, com a menor produçäo (32,1kg/vaca/dia). O teor de gordura no leite foi superior nos tratamentos com alto conteúdo de forragem na dieta, enquanto que a porcentagem de proteína seguiu padräo oposto. O híbrido bm3, em dieta contendo alta proporçäo de forragem, foi eficiente em manter o nível de desempenho de vacas de alta produçäo em comparaçäo à dietas com relaçöes forragem:concentrado normal ou alta e baseadas em híbridos contendo diferente genética de milho

Influence of mechanical processing on utilization of corn silage by lactating dairy cows.

We conducted three experiments to determine the influence of mechanical processing on corn silage utilization by lactating dairy cows. Total mixed rations contained either unprocessed or processed corn silage harvested between 1/4 and 3/4 milk line. In trial 1, 12 multiparous Holstein cows were used in a replicated double switchback design with 21-d periods. Intake of dry matter (DM) was increased 1.2 kg/d by processing, but milk yield was unaffected. Processing did not affect apparent total-tract DM digestibility, but processing tended to lower starch and corn excretion in feces and reduced concentration of sieved corn kernel particles in feces. In trial 2, 42 Holstein cows were used in an 18-wk randomized complete-block design. Intake of DM and milk yield were unaffected by processing, but milk fat percent was increased 0.35 percentage units by processing. Processing tended to increase total-tract digestibility of starch, but reduced organic matter, crude protein, and neutral detergent fiber digestibilities. In trial 3, 30 Holstein cows were used in a 15-wk randomized complete block design. There was no influence of mechanical processing on intake or lactation performance in this trial. Despite indications of increased starch digestion in two trials and increased DM intake in one trial, effects of processing corn silage on lactation performance were minimal with corn silage at the maturity and moisture contents used in these trials.