Effects of Feeding Formate-Treated Alfalfa Silage or Red Clover Silage on Omasal Nutrient Flow and Microbial Protein Synthesis in Lactating Dairy Cows

Feeding alfalfa-grass or red clover-grass mixture baleage: Effect on milk yield and composition, ruminal fermentation and microbiota taxa relative abundance, and nutrient utilization in dairy cows

Our goal was to investigate the effect of diets containing baleages harvested from alfalfa-grass or red clover-grass mixture on production performance, ruminal fermentation and microbiota taxa relative abundance, milk fatty acid profile, and nutrient utilization in dairy cows. Twenty Jersey cows (18 multiparous and 2 primiparous) averaging (mean ± SD) 148 ± 45.2 days in milk and 483 ± 65.4 kg of body weight in the beginning of the study were used in a randomized complete block design with repeated measures over time. The experiment lasted 9 wk, with a 2 wk covariate period followed by 7 wk of data and sample collection (wk 4 and 7 used in the statistical analyses). Cows were fed diets containing (dry matter basis) 35% of a concentrate mash and the following forage sources: (1) 65% second- and third-cut (32.5% each) alfalfa-grass mixture baleages (ALF) or (2) 65% second- and third-cut (32.5% each) red clover-grass mixture baleages (RC). Diets did not affect dry matter intake, milk yield, and concentrations of milk fat and true protein. In contrast, milk fat yield tended to decrease and energy-corrected milk yield decreased with feeding RC versus ALF. The apparent total-tract digestibilities of dry matter, organic matter, and ash-free neutral detergent fiber, milk proportions of trans-10 18:1, cis-9,cis-12,cis-15 18:3, and total n-3 fatty acids, ruminal molar proportion of acetate, and plasma concentrations of Leu, Phe, and Val all increased in RC versus ALF. Diet × week interactions were found for several parameters, most notably ruminal molar proportions of propionate and butyrate, ruminal NH3-N, milk urea N, plasma urea N, and plasma His concentrations, urinary N excretion, enteric CH4 production, and all energy efficiency variables. Specifically, ruminal NH3-N and plasma urea N concentrations, urinary excretion of N, and CH4 production decreased in cows fed RC in wk 4 but not in wk 7. Milk urea N concentration decreased and that of plasma His increased with feeding RC during wk 4 and 7, although the magnitude of treatments difference varied between the sampling periods. Efficiency of energy utilization calculated as milk energy/metabolizable energy decreased and that of tissue energy/ME increased in RC versus ALF cows in wk 4, suggesting that ME was portioned toward tissue and not milk in the RC diet. Interactions were also observed for the relative abundance of the rumen bacterial phyla Verrucomicrobiota and Fibrobacterota, with cows offered RC showing greater values than those receiving ALF in wk 4 but no differences in wk 7. Several diet × week interactions were detected in the present study implying short-term treatment responses and warranting further investigations.

Effect of red clover isoflavones on hormone, immune, inflammatory, and plasma biochemistry in lactating dairy cows

This study was to conducted to investigate the effect of red clover isoflavones on the health indicated by immune status and blood biochemistry in dairy cows. Sixty-eight healthy Holstein lactating cows were randomly divided into four treatments (n = 17 per treatment) from 5 blocks according to milk yield using a randomized complete block design. No initial differences in parity (2.13 ± 1.21), days in milk (165 ± 21 d), and milk yield (33.93 ± 3.81 kg/d) between groups. Cows were fed the basal diet supplemented with 0, 2, 4, or 8 g/kg red clover extract (RCE) in diet (dry matter based). Feeding, refusal feed weights, and milk yield were recorded three consecutive days in weeks 0, 4, 8, and 12. Blood was collected from the tail vein of the cows on the last day of weeks 4, 8 and 12, 1 h after the morning feeding, and analyzed for hormones, immunoglobulins, inflammatory markers, and markers of liver and kidney activities. The dry matter intake was significantly decreased by 3.7% in the 8 g/kg group (P < 0.05). The fat-corrected milk yield was significantly higher in both of the 2 and 4 g/kg groups (P < 0.01). Plasma estradiol and prolactin showed a quadratic effect with increasing RCE levels, with the highest in the 4 g/kg group (P < 0.05). Plasma tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β levels decreased linearly with increasing dietary RCE levels. Plasma IL-18 levels showed a quadratic effect with increasing dietary RCE levels, with significantly lower levels in both of the 2 and 4 g/kg groups (P < 0.05). Plasma immunoglobulin A and D-lactic acid levels showed a quadratic effect with increasing dietary RCE levels, with significantly higher level in the 4 g/kg group (P < 0.05). The liver function and kidney activity makers were similar (P > 0.05). These results recommend the supplementation of RCE at a level from 2 to 4 g/kg DM.

Impacts of red clover and sainfoin silages on the performance, nutrient utilization and milk fatty acids profile of ruminants: A meta-analysis

Inclusion of plants rich in secondary metabolites into grass ensiling offers multiple benefits for ruminants, from improving productive performance to health-promoting effects as well as helping to reduce environment pollution. The present meta-analysis summarizes the dietary inclusion levels of red clover silage (RCS) and sainfoin silages (SS) as well as the types of silages fed to dairy cows and small ruminants. A total of 37 in vivo studies (26 articles in dairy cows and 11 articles in small ruminants) were aggregated after being strictly selected using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A mixed model methodology was used to examine our objectives. This method declares the subject 'study' as random effects and 'inclusion level' as fixed effects. Results indicated that RCS proportion was not associated with nutrient digestibility except for a quadratic effect (p < 0.05) on neutral detergent fibre digestibility. Higher RCS inclusion linearly increased (p < 0.05) nitrogen (N) intake but had no effect on dairy cows' production. Increasing RCS proportion altered milk fatty acid profile where the concentration of conjugated linolenic acid (CLA), C18:3 α-linolenic acid (ALA) and C18:0 linearly increased (p < 0.01). In small ruminants, SS proportion had no relationship with nutrient digestibility, N metabolism and growth performance (p > 0.05). However, a combination of dietary RCS + SS resulted in significantly higher (p < 0.05) CLA and ALA concentration in cow milk and average daily gain (ADG) in small ruminants compared to diets composed from either grass silage or alfalfa silage. Altogether, this meta-analysis highlights the synergistic effects of a combination of SS + RCS inclusion in improving milk fatty acids (FA) profile of dairy cows and ADG of small ruminants.

Diets for Dairy Cows with Different Proportions of Crude Protein Originating from Red Clover Silage versus Soybean Meal: Ruminal Degradation and Intestinal Digestibility of Amino Acids

The purpose was to assess the effect of exchanging crude protein (CP) of soybean meal (SBM) with red clover silage (RCS) in total mixed rations (TMR) on ruminal degradation and intestinal digestibility (ID) of essential amino acids (EAA). Four TMR and their individual feed components were studied. The TMR were composed of forage and concentrates (75:25), with proportions of RCS in TMR of 0.15, 0.30, 0.45, and 0.60 on a dry matter basis, resulting in diet groups RCS15, RCS30, RCS45, and RCS60, respectively. The ruminal degradation of EAA was determined using the nylon bag technique. For this, samples of TMR and their individual feed components were ruminally incubated for 16 h. The feed residues of TMR obtained after 16 h of incubation were used for the determination of ID of EAA using the mobile-bag technique. Increasing RCS and reducing SBM proportions linearly increased (p < 0.01) the in situ ruminal degradation of individual EAA from 75.5% to 83.5%. The degradation of EAA followed the trend of CP degradation among TMR, except for Cys that was lower (p < 0.05) than that of CP in RCS60 (79.7% vs. 86.3%). The degradation of EAA in individual feed ingredients not always corresponded to the degradation of CP and was feed dependent. Increasing the proportions of RCS in the TMR linearly reduced (p < 0.001) the ID of EAA (except for Ile) from 78.2% to 67.3%. However, the ID of EAA did not always reflect the ID of CP, and in general, the differences between the ID of CP and EAA increased as RCS increased in the TMR. The ID values of most of the EAA were similar (p > 0.05) to ID of CP in RCS15 and RCS30, while they mostly differed (p < 0.05) in RCS45 and RCS60, and being higher for EAA than CP (except for Cys that was lower than CP, p < 0.05). Similar trends were observed for intestinal absorbable AA, resulting in higher values (p < 0.05) of intestinal absorbable for all EAA than of CP in diet RCS60. In conclusion, increasing levels of RCS in TMR reduced the extent of EAA flow into the small intestine, the ID of EAA, and consequently the intestinal absorbable EAA. Therefore, accurate determination of metabolizable AA must be considered for optimal diet formulation when including high proportions of RCS in diets of high-producing dairy cows.

Feeding diets varying in forage proportion and particle length to lactating dairy cows: II. Effects on duodenal flows and intestinal digestibility of amino acids

A study was conducted to evaluate the effects of forage-to-concentrate (F:C) ratio and forage particle length (FPL) on intake, duodenal flow, and digestibility of individual AA in the intestine of lactating dairy cows. The experiment was designed as a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments using 4 lactating dairy cows (parity 2) with ruminal and duodenal cannulas. Low (35:65) and high (60:40) F:C ratios (dry matter basis) were combined with 2 FPL of alfalfa silage (short vs. long; 7.9 vs. 19.1 mm). Few interactions between F:C and FPL for duodenal flow and intestinal digestibility of AA occurred, but interactions were detected for intakes of several AA. Intake of essential AA and nonessential AA decreased with increasing F:C, and the intake of several individual AA increased or decreased with increasing FPL. Increasing F:C decreased duodenal flows of essential AA, nonessential AA, and microbial AA due to consistent decreased flows of most individual AA (except Glu). Degradability of most individual AA in the rumen was not affected by F:C ratio or FPL except that the degradability of His was greater with high than low F:C diets, and the degradability of Ser was greater with long versus short FPL diets. However, the degradability of individual AA within diet varied considerably. Overall, F:C ratio and FPL did not affect intestinal digestibility of AA and rumen undegradable protein AA, whereas the digestibility of individual AA in the intestine varied considerably regardless of dietary treatment. These results indicate that increasing F:C ratio decreased AA supply due to decreased flow of AA to the duodenum but altering FPL did not affect AA supply. The results also revealed the necessity to consider both the flows and digestibility of individual AA when optimizing ration formulation to meet AA requirements of dairy cows.

Predictions of ruminal outflow of essential amino acids in dairy cattle

The objective of this work was to update and evaluate predictions of essential AA (EAA) outflows from the rumen. The model was constructed based on previously derived equations for rumen-undegradable (RUP), microbial (MiCP), and endogenous (EndCP) protein outflows from the rumen, and revised estimates of ingredient composition and EAA composition of the protein fractions. Corrections were adopted to account for incomplete recovery of EAA during 24-h acid hydrolysis. The predicted ruminal protein and EAA outflows were evaluated against a data set of observed values from the literature. Initial evaluations indicated a minor mean bias for non-ammonia, non-microbial nitrogen flow ([RUP + EndCP]/6.25) of 16 g of N per day. Root mean squared errors (RMSE) of EAA predictions ranged from 26.8 to 40.6% of observed mean values. Concordance correlation coefficients (CCC) of EAA predictions ranged from 0.34 to 0.55. Except for Leu, all ruminal EAA outflows were overpredicted by 3.0 to 32 g/d. In addition, small but significant slope biases were present for Arg [2.2% mean squared error (MSE)] and Lys (3.2% MSE). The overpredictions may suggest that the mean recovery of AA from acid hydrolysis across laboratories was less than estimates encompassed in the recovery factors. To test this hypothesis, several regression approaches were undertaken to identify potential causes of the bias. These included regressions of (1) residual errors for predicted EAA flows on each of the 3 protein-driven EA flows, (2) observed EAA flows on each protein-driven EAA flow, including an intercept, (3) observed EAA flows on the protein-driven EAA flows, excluding an intercept term, and (4) observed EAA flows on RUP and MiCP. However, these equations were deemed unsatisfactory for bias adjustment, as they generated biologically unfeasible predictions for some entities. Future work should focus on identifying the cause of the observed prediction bias.

An Overview of the Utilisation of Brewery By-Products as Generated by British Craft Breweries

There is a wide range of information available on by-product disposal methods used by large national breweries. However, little information is available on the methods of by-product disposal used by craft breweries. An investigation was carried out in which 200+ British craft brewers were contacted, of which 90 craft brewers provided basic information about their brewery operations and by-product disposal. Representatives of eleven breweries were interviewed to provide an in-depth case study of their by-product disposal methods. The research found that urban craft brewers use a wider range of disposal methods compared to rural craft brewers; urban brewers dispose of more waste through sewage and landfill, as well as using external companies, such as bio-recycling and anaerobic digester plants, whereas rural brewers have relationships with farmers who dispose of the by-products in various ways. Craft brewers tend to have a direct relationship with the by-product users. Even though they do not have all disposal options available to them which the large industrial breweries have, due to their small scale of by-product production, craft brewers appear to find alternative means of sustainability.

Compartmental flux andin situmethods underestimate total feed nitrogen as judged by the omasal sampling method due to ignoring soluble feed nitrogen flow

The objective of the present study was to estimate ruminal feed N outflow in lactating cows using the omasal sampling, compartmental flux orin situmethod. A total of five ruminally fistulated Finnish Ayrshire dairy cows were used in a 5 × 5 Latin square study with 21 d periods. Experimental silages of grass or red clover harvested at two stages of maturity in addition to a supplement of 9·0 kg concentrate/d were fed to the cows.In vivoomasal N flow was determined using the omasal sampling technique. Ruminalin situN flow was calculated from N intake and degradability (38 μm nylon bags). The samples of ruminal contents and faeces were divided into seven particle-size fractions by wet sieving; the concentrations of indigestible neutral-detergent fibre and N were used to calculate N flow in the compartmental flux method.In vivoomasal N flow was greater for the red clover silage diets than for the grass silage diets. The N flow calculated using the compartmental flux technique and that calculated using thein situtechnique were highly correlated, but both were less than and poorly correlated with thein vivoN flow. In bothin situand compartmental flux techniques, forage maturity increased the particle-associated N flow, with the increase being significantly greater for the red clover diets than for the grass silage diets. In conclusion, the compartmental flux andin situmethods described the N flow associated with the particle fractions rather than the total ruminal outflow of feed N.

Effects of feeding different linseed sources on omasal fatty acid flows and fatty acid profiles of plasma and milk fat in lactating dairy cows

The aim of this experiment was to study the effects of feeding different linseed sources on omasal fatty acid (FA) flows, and plasma and milk FA profiles in dairy cows. Four ruminally cannulated lactating Holstein-Friesian cows were assigned to 4 dietary treatments in a 4×4 Latin square design. Dietary treatments consisted of supplementing crushed linseed (CL), extruded whole linseed (EL), formaldehyde-treated linseed oil (FL) and linseed oil in combination with marine algae rich in docosahexaenoic acid (DL). Each period in the Latin square design lasted 21 d, with the first 16 d for adaptation. Omasal flow was estimated by the omasal sampling technique using Cr-EDTA, Yb-acetate, and acid detergent lignin as digesta flow markers. The average DM intake was 20.6 ± 2.5 kg/d, C18:3n-3 intake was 341 ± 51 g/d, and milk yield was 32.0 ± 4.6 kg/d. Milk fat yield was lower for the DL treatment (0.96 kg/d) compared with the other linseed treatments (CL, 1.36 kg/d; EL, 1.49 kg/d; FL, 1.54 kg/d). Omasal flow of C18:3n-3 was higher and C18:3n-3 biohydrogenation was lower for the EL treatment (33.8 g/d; 90.9%) compared with the CL (21.8 g/d; 94.0%), FL (15.5 g/d; 95.4%), and DL (4.6 g/d; 98.5%) treatments, whereas whole-tract digestibility of crude fat was lower for the EL treatment (64.8%) compared with the CL (71.3%), FL (78.5%), and DL (80.4%) treatments. The proportion of C18:3n-3 (g/100 g of FA) was higher for the FL treatment compared with the other treatments in plasma triacylglycerols (FL, 3.60; CL, 1.22; EL, 1.35; DL, 1.12) and milk fat (FL, 3.19; CL, 0.87; EL, 0.83; DL, 0.46). Omasal flow and proportion of C18:0 in plasma and milk fat were lower, whereas omasal flow and proportions of biohydrogenation intermediates in plasma and milk fat were higher for the DL treatment compared with the other linseed treatments. The results demonstrate that feeding EL did not result in a higher C18:3n-3 proportion in plasma and milk fat despite the higher omasal C18:3n-3 flow. This was related to the decreased total-tract digestibility of crude fat. Feeding FL resulted in a higher C18:3n-3 proportion in plasma and milk fat, although the omasal C18:3n-3 flow was similar or lower than for the CL and EL treatment, respectively. Feeding DL inhibited biohydrogenation of trans-11,cis-15-C18:2 to C18:0, as indicated by the increased omasal flows and proportions of biohydrogenation intermediates in plasma and milk fat.

A meta-analysis of the effects of dietary protein concentration and degradability on milk protein yield and milk N efficiency in dairy cows

Data sets from North American (NA, 739 diets) and North European (NE, 998 diets) feeding trials with dairy cows were evaluated to investigate the effects of dietary crude protein (CP) intake and ruminal degradability on milk protein yield (MPY) and efficiency of N utilization for milk protein synthesis (MNE; milk N / N intake) in dairy cows. The NA diets were based on corn silage, alfalfa silage and hay, corn and barley grains, and soybean meal. The NE diets were based on grass silage, barley and oats grains, and soybean and rapeseed meals. Diets were evaluated for rumen-degradable and undegradable protein (RDP and RUP, respectively) concentrations according to NRC (2001). A mixed model regression analysis with random study effect was used to evaluate relationships between dietary CP concentration and degradability and MPY and MNE. In both data sets, CP intake alone predicted MPY reasonably well. Addition of CP degradability to the models slightly improved prediction. Models based on metabolizable protein (MP) intake predicted MPY better than the CP or the CP-CP degradability models. The best prediction models were based on total digestible nutrients (TDN) and CP intakes. Similar to the MPY models, inclusion of CP degradability in the CP (intake or concentration) models only slightly improved prediction of MNE in both data sets. Concentration of dietary CP was a better predictor of MNE than CP intake. Compared with the CP models, prediction of MNE was improved by inclusion of TDN intake or concentration. Milk yield alone was a poor predictor of MNE. The models developed from one data set were validated using the other data set. The MNE models based on TDN and CP intake performed well as indicated by small mean and slope bias. This meta-analysis demonstrated that CP concentration is the most important dietary factor influencing MNE. Ruminal CP degradability as predicted by NRC (2001) does not appear to be a significant factor in predicting MPY or MNE. Data also indicated that increasing milk yield will increase MNE provided that dietary CP concentration is not increased, but the effect is considerably smaller than the effect of reducing CP intake.

Effect of source of rumen-degraded protein on production and ruminal metabolism in lactating dairy cows

Twenty-eight (8 with ruminal cannulas) lactating Holstein cows were assigned to seven 4 x 4 Latin squares in a 16-wk trial to study the effects on production and ruminal metabolism of feeding differing proportions of rumen-degraded protein (RDP) from soybean meal and urea. Diets contained [dry matter (DM) basis] 40% corn silage, 15% alfalfa silage, 28 to 30% high-moisture corn, plus varying levels of ground dry shelled corn, solvent- and lignosulfonate-treated soybean meal, and urea. Proportions of the soybean meals, urea, and dry corn were adjusted such that all diets contained 16.1% crude protein and 10.5% RDP, with urea providing 0, 1.2, 2.4, and 3.7% RDP (DM basis). As urea supplied greater proportions of RDP, there were linear decreases in DM intake, yield of milk, 3.5% fat-corrected milk, fat, protein, and solids-not-fat, and of weight gain. Milk contents of fat, protein, and solids-not-fat were not affected by source of RDP. Replacing soybean meal RDP with urea RDP resulted in several linear responses: increased excretion of urinary urea-N and concentration of milk urea-N, blood urea-N, and ruminal ammonia-N and decreased excretion of fecal N; there was also a trend for increased excretion of total urinary N. A linear increase in neutral detergent fiber (NDF) digestibility, probably due to digestion of NDF-N from lignosulfonate-treated soybean meal, was observed with greater urea intake. Omasal sampling revealed small but significant effects of N source on measured RDP supply, which averaged 11.0% (DM basis) across diets. Increasing the proportion of RDP from urea resulted in linear decrease in omasal flow of dietary nonammonia N (NAN) and microbial NAN and in microbial growth efficiency (microbial NAN/unit of organic matter truly digested in the rumen). These changes were paralleled by large linear reductions in omasal flows of essential, nonessential, and total amino acids. Overall, these results indicated that replacing soybean meal RDP with that from urea reduced yield of milk and milk components, largely because of depressed microbial protein formation in the rumen and that RDP from nonprotein-N sources was not as effective as RDP provided by true protein.

Effects of Different Protein Supplements on Omasal Nutrient Flow and Microbial Protein Synthesis in Lactating Dairy Cows

Eight ruminally cannulated Holstein cows that were part of a larger lactation trial were used in 2 replicated 4 x 4 Latin squares to quantify effects of supplementing protein as urea, solvent soybean meal (SSBM), cottonseed meal (CSM), or canola meal (CM) on omasal nutrient flows and microbial protein synthesis. All diets contained (% of dry matter) 21% alfalfa silage and 35% corn silage plus 1) 2% urea plus 41% high-moisture shelled corn (HMSC), 2) 12% SSBM plus 31% HMSC, 3) 14% CSM plus 29% HMSC, or 4) 16% CM plus 27% HMSC. Crude protein was equal across diets, averaging 16.6%. The CSM diet supplied the least rumen-degraded protein and the most rumen-undegraded protein. Microbial nonammonia N flow was similar among the true protein supplements but was 14% lower in cows fed urea. In vivo ruminal passage rate, degradation rate, and estimated escape for the 3 true proteins were, respectively, 0.044/h, 0.105/h, and 29% for SSBM; 0.051/h, 0.050/h, and 51% for CSM; and 0.039/h, 0.081/h, and 34% for CM. This indicated that CSM protein was less degraded because of both a faster passage rate and slower degradation rate. Omasal flow of individual AA, branched-chain AA, essential AA, nonessential AA, and total AA all were lower in cows fed urea compared with one of the true protein supplements. Among the 3 diets supplemented with true protein, omasal flow of Arg was greatest on CSM, and omasal flow of His was greatest on CSM, intermediate on CM, and lowest on SSBM. Lower flows of AA and microbial nonammonia N explained lower yields of milk yield and milk components observed on the urea diet in the companion lactation trial. These results clearly showed that supplementation with true protein was necessary to obtain sufficient microbial protein and rumen-undegraded protein to meet the metabolizable AA requirements of high-producing dairy cows.

Effects of Different Protein Supplements on Milk Production and Nutrient Utilization in Lactating Dairy Cows

Sixteen (8 ruminally cannulated) multiparous and 8 primiparous lactating Holstein cows were used in 6 replicated 4 x 4 Latin squares to test the effects of feeding supplemental protein as urea, solvent soybean meal (SSBM), cottonseed meal (CSM), or canola meal (CM) on milk production, nutrient utilization, and ruminal metabolism. All diets contained (% of DM) 21% alfalfa silage and 35% corn silage plus 1) 2% urea plus 41% high-moisture shelled corn (HMSC), 2) 12% SSBM plus 31% HMSC, 3) 14% CSM plus 29% HMSC, or 4) 16% CM plus 27% HMSC. Crude protein was equal across diets, averaging 16.6%. Intake and production were substantially reduced, and milk urea, blood urea, and ruminal ammonia were increased on urea vs. the diets supplemented with true protein. Although intake was lower in cows fed SSBM compared with CM, no differences were observed for milk yield among SSBM, CSM, and CM. Yields of fat and protein both were lower on CSM than on CM, whereas SSBM was intermediate. Milk urea and milk protein contents also decreased when CSM replaced SSBM or CM. Diet did not affect ruminal volatile fatty acids except that isobutyrate concentration was lowest on urea, intermediate on CSM, and greatest on SSBM and CM. Urinary excretion of urea N and total N was greatest on urea, intermediate on SSBM and CM, and lowest on CSM. Apparent N efficiency (milk N/N intake) was lower on the CSM diet than on the SSBM diet. Overall, production and N utilization were compromised when the diets of high-yielding dairy cows were supplemented with urea rather than true protein and the value of the true proteins.

Effects of Feeding Formate-Treated Alfalfa Silage or Red Clover Silage on the Production of Lactating Dairy Cows

In trial 1, 15 Holsteins were fed 3 total mixed rations (TMR) with 33% neutral detergent fiber in 3 x 3 Latin squares (28-d periods). Two TMR contained (dry matter basis): 40% control alfalfa silage (CAS) or 40% ammonium tetraformate-treated alfalfa silage (TAS), 20% corn silage (CS), 33% high-moisture shelled corn (HMSC), 6% solvent soybean meal (SSBM), and 18% crude protein (CP); the third TMR contained 54% red clover silage (RCS), 6% dried molasses, 33% HMSC, 6% SSBM, and 16.3% CP. Silages differed in nonprotein N (NPN) and acid detergent insoluble N (ADIN; % of total N): 50 and 4% (CAS); 45 and 3% (TAS); 27 and 8% (RCS). Replacing CAS with TAS increased intake, yields of milk, fat-corrected milk, protein, and solids-not-fat, and apparent dry matter and N efficiency. Replacing CAS with RCS increased intake and N efficiency but not milk yield. Replacing CAS or TAS with RCS lowered milk urea N, increased apparent nutrient digestibility, and diverted N excretion from urine to feces. In trial 2, 24 Holsteins (8 ruminally cannulated) were fed 4 TMR in 4 x 4 Latin squares (28-d periods). Diets included the CAS, TAS, and RCS (RCS1) fed in trial 1 plus an immature RCS (RCS2; 29% NPN, 4% ADIN). The CAS, TAS, and RCS2 diets contained 36% HMSC and 3% SSBM and the RCS1 diet contained 31% HMSC and 9% SSBM. All TMR had 50% legume silage, 10% CS, 27% neutral detergent fiber, and 17 to 18% CP. Little difference was observed between cows fed CAS and TAS. Intakes of DM and yields of milk, fat-corrected milk, fat, protein, lactose, and solids-not-fat, and milk fat and protein content were greater on alfalfa silage vs. RCS. Blood urea N, milk urea N, ruminal ammonia, and total urinary N excretion were reduced on RCS, suggesting better N utilization on the lower NPN silage. Apparent N efficiency tended to be higher for cows fed RCS but there was no difference when N efficiency was expressed as kilograms of milk yield per kilogram of total N excreted.