Lactational performance,enteric gas emissions,and plasma amino acid profile of dairy cows fed diets with soybean or canola meals included on an equal protein basis

This study investigated the effects of feeding solvent-extracted canola meal (CM), extruded soybean meal (ESBM), or solvent-extracted soybean meal (SSBM) on an equivalent crude protein basis on performance, plasma AA profiles, enteric gas emissions, milk fatty acids, and nutrient digestibility in lactating dairy cows. Fifteen Holstein cows (95 ± 20 d in milk) were used in a replicated 3 × 3 Latin square design experiment with 3 periods of 28 d each. Treatments were 3 diets containing 17.1% CM, 14.2% ESBM, or 13.6% SSBM (dry matter basis). Vegetable oil was added (canola oil for CM or soybean oil for SSBM) to equalize the ether extract concentration of the diets. Rumen-protected Met was supplemented targeting digestible Met supply of 2.2% of metabolizable protein in all diets. Canola meal increased dry matter intake (DMI) by 5.9 and 8.9% in comparison with ESBM and SSBM, respectively. Milk urea nitrogen was lowest in CM, followed by SSBM, and was highest for ESBM. No differences were observed in feed efficiency, energy-corrected milk yield, and milk composition or component yields among treatments. Cows fed CM emitted less enteric CH₄ per kg of DMI compared with both ESBM and SSBM, but CH₄ emission intensity (CH₄ per kg of energy-corrected milk) was similar among treatments. In summary, replacement of ESBM or SSBM with CM, on an equal crude protein basis, in the diet of lactating dairy cows enhanced DMI, but yields of energy-corrected milk and milk components and feed efficiency were similar among treatments.     

The relative merit of ruminal undegradable protein from soybean meal or soluble fiber from beet pulp to improve nitrogen utilization in dairy cows

Early lactating dairy cows were used to determine whether the replacement of solvent-extracted soybean meal [SSBM; a source of rumen-degradable protein (RDP)] with expeller soybean meal (ESBM; a source of rumen-undegradable protein), or the replacement of high-moisture shelled corn (HMSC) with beet pulp (a source of soluble fiber) would be effective in improving efficiency of N usage for milk production. The study was designed as a replicated 4 × 4 Latin square with 21-d periods. Eight multiparous Holstein cows were fed, ad libitum, the following diets, which were based on alfalfa silage and HMSC, and formulated to be isocaloric: 1) basal diet without a protein supplement (negative control diet: NC); 2) NC supplemented with solvent-extracted SBM (diet SSBM); 3) NC supplemented with expeller SBM (diet ESBM); 4) SSBM in which unmolassed dried beet pulp replaced half of the HMSC (diet SSBMBP). Compared with diet NC, protein supplementation increased intake of organic matter and dry matter. Milk and milk protein yields were lower with NC but this diet resulted in the greatest efficiency of N usage for milk production (30% milk N/N intake). Supplementation with ESBM, a proven source of RUP, increased plasma concentrations of histidine and branched-chain amino acids, and reduced milk urea N concentration, but failed to improve the yields of milk or milk protein. Milk fat yield tended to decrease with RUP supplementation. Replacing part of HMSC with soluble fiber from beet pulp (SSBMBP) tended to decrease milk production compared with SSBM; the effect was due to a reduction in dry matter intake. There were no differences among diets SSBM, ESBM, or SSBMBP in urinary excretion of purine derivatives. Neither substitution of ESBM for SSBM nor partial replacement of HMSC with beet pulp altered the efficiency of N usage for milk production or manure N excretion.     

Effect of amount and ruminal degradability of soybean meal protein on performance of lactating dairy cows

Twenty-eight Holstein cows (4 with ruminal cannulas) were blocked by days in milk into 7 groups and then randomly assigned to 1 of 7 balanced 4 × 4 Latin square diet sequences. The diets contained [dry matter (DM) basis] 20% alfalfa silage, 35% corn silage, and 45% concentrate mainly from high-moisture corn and soybean meal. Diets differed in crude protein (CP) content and source of protein supplement: diet A) 15.6% CP, 3.7% solvent-extracted soybean meal (SSBM), 4.5% expeller soybean meal (ESBM); diet B) 16.6% CP, 9.6% SSBM, 0% ESBM; diet C) 16.6% CP, 4.6% SSBM, 5.9% ESBM; and diet D) 17.6% CP, 11.7% SSBM, 0% ESBM. Each experimental period consisted of 14 d for adaptation plus 14 d for collection of production data. Sampling of ruminal digesta and spot sampling of blood, feces, and urine was done on d 26 and 27 of each period. Planned contrasts compared included diet A vs. diet B, diet B vs. diet C, and diet B vs. diet D. There were no effects of diet on most of the production traits measured. However, milk yield tended to be higher for diet B vs. A. Trends were also detected for higher DM intake and weight gain and lower milk yield/DM intake in cows fed diet D vs. diet B. Milk lactose content was higher on diets A and C than on B. Ruminal NH₃ was higher on diet D vs. B, but other ruminal metabolites, apparent nutrient digestibility, and estimated bacterial CP synthesis did not differ across diets. Blood and milk urea-N were higher on diets C and D than on B; milk urea-N was higher on diet B than on A. Increasing dietary CP from 16.6% (diet B) to 17.6% (diet D) increased urinary N excretion by 54 g/d and reduced apparent N efficiency (milk N/N intake) by 2.5 percentage units, without altering yield. Under the conditions of this trial, milk production was not improved by feeding rumen-undegraded protein from ESBM or greater amounts of rumen-degraded protein from SSBM. Feeding more than 16.6% CP depressed N efficiency.     

Production effects of extruded soybean meal replacing canola meal in the diet of lactating dairy cows

This study investigated the effects of extruded soybean meal (ESBM) in comparison with canola meal (CM) fed on an equivalent crude protein (CP) basis on lactational performance and ruminal fermentation of dairy cows. Following a 2-wk covariate period, 48 Holstein cows averaging (±SD): 146 ± 46 d in milk (DIM) and 43 ± 7 kg/d milk yield (MY) were assigned 1 of 2 treatment diets in a randomized complete block design experiment, which included a 2-wk period for dietary treatment adaptation before experimental data were collected. Following the adaptation period, samples and experimental data were collected for a total of 7 wk. Cows were blocked based on parity, DIM, and MY. Treatment diets contained 15.8% CM (containing 41.2% CP) or 13.2% ESBM (with 48.7% CP) of total mixed ration dry matter (DM), with similar inclusion of other feed ingredients. The CM diet was supplemented with canola oil, whereas the ESBM diet was supplemented with soybean hulls to achieve similar ether extract and neutral detergent fiber contents between the diets. Urea and rumen-protected Met and Lys were added to both diets to meet or exceed cow recommendations. Whole-ruminal digesta samples were collected from 10 (5 per treatment) ruminally cannulated cows. Eight cannulated cows were removed during the last week of the experiment to participate in another study. Treatment did not affect DM intake and MY or energy-corrected MY of the cows. Energy-corrected MY, apart from experimental wk 5, was similar between treatments. Apart from experimental wk 3 and 7, milk fat concentration and yield were greater for cows fed ESBM compared with CM. In multiparous cows only, milk true protein yield was greater for cows fed CM compared with ESBM. Ruminal concentration of total volatile fatty acids and the molar proportion of acetate were greater for ESBM, and propionate and valerate were greater in cows fed CM. Acetate to propionate ratio was greater for cows fed ESBM versus CM diet. Compared with the CM diet, the ESBM diet increased plasma concentrations of Ile, Leu, and Phe but not the sum of essential AA. Apparent total-tract digestibility of acid detergent fiber was greater in cows fed ESBM relative to CM. In this experiment, CM and ESBM included on an equal CP basis in the diet of dairy cows, resulted in similar DM intake, MY, and feed efficiency.     

Effect of high-oleic-acid soybeans on production performance,milk fatty acid composition,and enteric methane emission in dairy cows

The objective of this study was to investigate the effect of 3 soybean sources differing in fatty acid profile and processing method on productivity, milk composition, digestibility, rumen fermentation, and enteric methane emission in lactating dairy cows. The soybean sources were conventional, high-linoleic-acid variety extruded soybean meal (ESBM; 8.7% ether extract with 15% oleic and 54% linoleic acids); extruded Plenish (DuPont Pioneer, Johnston, IA), high-oleic-acid variety soybean meal (EPSBM; 8.4% ether extract with 73% oleic and 8% linoleic acids); and whole, heated Plenish soybeans (WPSB; 20.2% ether extract). The study involved 15 Holstein cows in a replicated 3 × 3 Latin square design experiment with three 28-d periods. The inclusion rate of the soybean sources in the diet was (dry matter basis) 17.1, 17.1, and 7.4% for ESBM, EPSBM, and WPSB, respectively, which resulted in ether extract concentration of the diets of 3.99, 3.94, and 4.18%, respectively. Compared with ESBM, the Plenish diets tended to increase dry matter intake and decreased feed efficiency (but had no effect on energy-corrected milk feed efficiency). The Plenish diets increased milk fat concentration on average by 5.6% and tended to increase milk fat yield, compared with ESBM. The WPSB diet tended to increased milk true protein compared with the extruded soybean meal diets. Treatments had no effect on rumen fermentation and enteric methane or carbon dioxide emissions, except pH was higher for WPSB versus EPSBM. The Plenish diets decreased the prevalence of Ruminococcus and increased that of Eubacterium and Treponema in whole ruminal contents. Total-tract apparent digestibility of organic matter and crude protein were decreased by WPSB compared with ESBM and EPSBM. Compared with the other treatments, urinary N excretion was increased by EPSBM and fecal N excretion was greater for WPSB. Treatments had marked effects on milk fatty acid profile. Generally, the Plenish diets increased mono-unsaturated (mostly cis-9 18:1) and decreased polyunsaturated, total trans-, and conjugated linoleic fatty acids concentrations in milk fat. In this study, compared with conventional, high-linoleic-acid variety extruded soybean meal, the Plenish soybean diets increased milk fat concentration and tended to increase fat yield, decreased feed efficiency, and modified milk fatty acid profile in a manner expected from the greater concentration of oleic acid in Plenish soybean oil.     

Effects of feeding dairy cows protein supplements of varying ruminal degradability

Twenty-five (10 ruminally cannulated) Holstein cows averaging 82 +/- 34 d in milk were assigned to 5 x 5 Latin squares (21-d periods) and fed diets supplemented with one of four different proteins to assess effects on production, ruminal metabolism, omasal flow of N fractions, and degradation rates of protein supplements. Total mixed diets contained (dry matter basis) 44% corn silage, 22% alfalfa silage, 2% urea, and 31% concentrate. Five concentrate mixes were fed: 31% high-moisture shelled corn (HMSC; basal); 9% solvent soybean meal (SSBM), 22% HMSC; 10% expeller soybean meal (ESBM), 21% HMSC; 5.5% blood meal (BM), 25.5% HMSC; and 7% corn gluten meal (CGM), 24% HMSC. Diets averaged, respectively, 15.8, 19.1, 19.7, 20.3, and 19.3% crude protein. Feeding the basal diet reduced intake and yield of milk, fat-corrected milk (FCM), and all milk components compared to the protein-supplemented diets. Milk yield was higher for cows fed ESBM and CGM, fat yield was higher for cows fed SSBM and CGM, but FCM and protein yields were not different among cows fed supplemental protein. Based on omasal sampling, mean in vivo estimates of ruminal degradation rate for the crude protein in SSBM, ESBM, BM, and CGM was, respectively, 0.417, 0.179, 0.098, and 0.051/h (computed using passage rates observed for the small particle phase; mean = 0.14/h), and 0.179, 0.077, 0.042, and 0.026/h (computed using a passage rate of 0.06/h). The in vivo degradation rate computed for SSBM at a passage rate = 0.06/h was similar to that estimated using the inhibitor in vitro method. However, in vivo degradation rates computed at passage rate = 0.06/h for ESBM, BM, and CGM were about two, four, and three times more rapid than those estimated by inhibitor in vitro. Experimental proteins fed in this trial will be used as standards for developing in vitro methods for predicting rates of ruminal protein degradation.     

Rumen fermentation and intestinal supply of nutrients in dairy cows fed rumen-protected soy products

Four multiparous lactating Holstein cows that were fistulated in the rumen and duodenum and that averaged 205 d in milk were used in a 4 × 4 Latin square design to evaluate the practical replacement of solvent-extracted soybean meal (SSBM) with soy protein products of reduced ruminal degradability. On a dry matter (DM) basis, diets contained 15% alfalfa silage, 25% corn silage, 34.3 to 36.9% corn grain, 19.4% soy products, 18.2% crude protein, 25.5% neutral detergent fiber, and 35.3% starch. In the experimental diets, SSBM was replaced with expeller soybean meal (ESBM); heated, xylose-treated soybean meal (NSBM); or whole roasted soybeans (WRSB) to supply 10.2% of the dietary DM. Intakes of DM (mean = 20.4 kg/d), organic matter, and starch were unaffected by the source of soy protein. Similarly, true ruminal fermentation of organic matter and apparent digestion of starch in the rumen and total tract were not altered by treatments. Intake of N ranged from 567 (WRSB) to 622 g/d (ESBM), but differences among soy protein supplements were not significant. Compared with SSBM, the ruminal outflow of nonammonia N was higher for NSBM, tended to be higher for ESBM, and was similar for WRSB. The intestinal supply of nonammonia nonmicrobial N was higher for NSBM and WRSB and tended to be higher for ESBM than for SSBM. However, no differences were detected among treatments when the flow to the duodenum of nonammonia nonmicrobial N was expressed as a percentage of N intake or nonammonia N flow. The ruminal outflow of microbial N, Met, and Lys was not altered by the source of soy protein. Data suggest that partially replacing SSBM with ESBM, NSBM, or WRSB may increase the quantity of feed protein that reaches the small intestines of dairy cows. However, significant improvements in the supply of previously reported limiting amino acids for milk production, particularly of Met, should not be expected.     

Enteric methane emission,milk production,and composition of dairy cows fed 3-nitrooxypropanol

This study examined the effect of 3-nitrooxypropanol (3-NOP), an investigational substance, on enteric methane emission, milk production, and composition in Holstein dairy cows. Following a 3-wk covariate period, 48 multi- and primiparous cows averaging (± standard deviation) 118 ± 28 d in milk, 43.4 ± 8 kg/d milk yield, and 594 ± 57 kg of body weight were blocked based on days in milk, milk yield, and enteric methane emission and randomly assigned to 1 of 2 treatment groups: (1) control, no 3-NOP, and (2) 3-NOP applied at 60 mg/kg feed dry matter. Inclusion of 3-NOP was through the total mixed ration and fed for 15 consecutive weeks. Cows were housed in a freestall barn equipped with a Calan Broadbent Feeding System (American Calan Inc., Northwood, NH) for monitoring individual dry matter intake and fed ad libitum once daily. Enteric gaseous emissions (methane, carbon dioxide, and hydrogen) were measured using 3 GreenFeed (C-Lock Inc., Rapid City, SD) units. Dry matter intake, cow body weight, and body weight change were not affected by 3-NOP. Compared with the control group, 3-NOP applied at 60 mg/kg feed dry matter decreased daily methane emission, emission yield, and emission intensity by 26, 27, and 29%, respectively. Enteric emission of carbon dioxide was not affected, and hydrogen emission was increased 6-fold by 3-NOP. Administration of 3-NOP had no effect on milk and energy-corrected milk yields and feed efficiency, increased milk fat and milk urea nitrogen concentrations, and increased milk fat yield but had no other effects on milk components. Concentration of C6:0 and C8:0 and the sum of saturated fatty acids in milk fat were increased by 3-NOP. Total trans fatty acids and the sum of polyunsaturated fatty acids were decreased by 3-NOP. In this experiment, 3-NOP decreased enteric methane daily emission, yield, and intensity without affecting dry matter intake and milk yield, but increased milk fat in high-producing dairy cows.     

Replacing human-edible feed ingredients with by-products increases net food production efficiency in dairy cows

Global demand for food is increasing, and use of large amounts of potentially human-edible feedstuffs for dairy cows is an important concern. The present study examined whether feeding a by-product-based concentrate combined with high-quality grass silage to high-producing dairy cows affected feed intake and milk production compared with a conventional diet, as well as the effect on efficiency of human food production. In a changeover experiment with four 21-d periods, 24 dairy cows in mid-lactation were offered 9.6 kg of dry matter per day with 1 of 4 concentrates and high-quality grass silage ad libitum. The control concentrate was based on cereal grain (wheat, oat, and barley) and soybean meal, whereas the 3 by-product-based concentrates contained sugar beet pulp in combination with mainly heat-treated rapeseed meal, distillers grain, or a mixture of both. All diets were formulated to be isoenergetic and isonitrogenous. The cows had 10-fold higher starch intake when fed the control diet than when fed the by-product-based concentrates. Silage intake (13 kg of dry matter/d) and milk production (33 kg of energy-corrected milk/d) were not affected by the change in diet. Therefore, replacing cereals and soybean meal with human-inedible by-products in a high-quality forage diet to dairy cows increased net food protein production substantially without lowering milk production.     

Peas can replace soybean meal and corn grain in dairy cow diets

The objective of this experiment was to investigate the effect of a partial substitution of soybean meal and corn grain with field peas in dairy cow diets on intake, milk yield and composition, nutrient digestibility, and urinary and fecal N losses. Twenty-four lactating Holstein cows were blocked into 2 groups based on parity, days in milk, and milk yield at the end of a 2-wk covariate period. Cows within group were randomly assigned to 1 of 2 treatments: control and pea diets. Approximately 45% of the corn grain and 78% of the soybean meal in the control diet were replaced with 15% (dry matter basis) field peas in the experimental diet. The peas used in the trial contained 25% crude protein and an estimated 1.98 Mcal of net energy for lactation/kg. The experiment continued for 70 d. Dry matter intake (25.9 and 26.3 kg/d; control and pea diets, respectively), milk yield (35.4 and 35.6 kg/d), 4% fat-corrected milk yield (33.0 and 34.6 kg/d), milk fat (3.54 and 3.76%) and protein (3.00 and 2.99%) content and yields, and milk N efficiency (26 and 24%) were not affected by diet. Concentration of milk urea nitrogen was also not affected by treatment (14.3 and 15.0 mg/dL, respectively). Intake of organic matter and N were not affected by diet, but intake of neutral detergent fiber was lower and that of starch greater with the control diet. Total tract apparent digestibility of starch was lower (92.1 vs. 88.3%, respectively) and that of dry matter and organic matter tended to be lower with the pea compared with the control diet. Urinary and fecal N losses were not different between the 2 diets. Panel evaluation of milk from the 2 diets indicated no differences in the organoleptic characteristics of milk. This experiment demonstrated that field peas could be safely fed to high-producing dairy cows at a 15% inclusion rate, replacing soybean meal and corn grain. At this inclusion rate, no effects on milk yield or milk composition were observed.     

Ruminal degradability and lysine bioavailability of soybean meals and effects on performance of dairy cows

Evaluations of 4 soybean meal (SBM) products were conducted in 3 experiments. The 4 products were 1) solvent SBM (SSBM), 2) SSBM treated with 0.05% baker's yeast and toasted at 100°C (YSBM), 3) expeller SBM (ESBM), and 4) lignosulfonate-treated SBM (LSBM). Multiparous Holstein cows (n = 32; 152 ± 63 d in milk; body weight = 708 ± 77 kg; producing 41 ± 7 kg/d of milk at the beginning of the study) were used in a 4 × 4 Latin square design with 28-d periods to investigate cow responsiveness to supplemental ruminally undegradable protein (RUP) from the SBM products. Dietary treatments were formulated by substituting all of the SSBM and part of the ground corn with YSBM, ESBM, or LSBM to yield isonitrogenous diets. Diets were formulated to provide adequate ruminally degradable protein, but deficient RUP and metabolizable protein supplies. No differences among dietary treatments were observed for dry matter intake, body weight gain, milk and component yields, or efficiency of milk production. The lack of response to changes in SBM source was likely due to an adequate RUP and metabolizable protein supply by all the diets. In situ ruminal degradations of YSBM and LSBM were slower than those of SSBM or ESBM; thus, RUP contents of YSBM and LSBM were greater than those of SSBM or ESBM. The RUP of all SBM products had similar small intestinal digestibility. Available Lys contents, estimated chemically or by using a chick growth assay, were less for YSBM and LSBM than for SSBM or ESBM, suggesting deleterious effects of processing on Lys availability in YSBM and LSBM.     

Inclusion of brown midrib dwarf pearl millet silage in the diet of lactating dairy cows

Brown midrib brachytic dwarf pearl millet (Pennisetum glaucum) forage harvested at the flag leaf visible stage and subsequently ensiled was investigated as a partial replacement of corn silage in the diet of high-producing dairy cows. Seventeen lactating Holstein cows were fed 2 diets in a crossover design experiment with 2 periods of 28 d each. Both diets had forage:concentrate ratios of 60:40. The control diet (CSD) was based on corn silage and alfalfa haylage, and in the treatment diet, 20% of the corn silage dry matter (corresponding to 10% of the dietary dry matter) was replaced with pearl millet silage (PMD). The effects of partial substitution of corn silage with pearl millet silage on dry matter intake, milk yield, milk components, fatty acid profile, apparent total-tract digestibility of nutrients, N utilization, and enteric methane emissions were analyzed. The pearl millet silage was higher in crude protein and neutral detergent fiber and lower in lignin and starch than the corn silage. Diet did not affect dry matter intake or energy-corrected milk yield, which averaged 46.7 ± 1.92 kg/d. The PMD treatment tended to increase milk fat concentration, had no effect on milk fat yield, and increased milk urea N. Concentrations and yields of milk protein and lactose were not affected by diet. Apparent total-tract digestibility of dry matter decreased from 66.5% in CSD to 64.5% in PMD. Similarly, organic matter and crude protein digestibility was decreased by PMD, whereas neutral- and acid-detergent fiber digestibility was increased. Total milk trans fatty acid concentration was decreased by PMD, with a particular decrease in trans-10 18:1. Urinary urea and fecal N excretion increased with PMD compared with CSD. Milk N efficiency decreased with PMD. Carbon dioxide emission was not different between the diets, but PMD increased enteric methane emission from 396 to 454 g/d and increased methane yield and intensity. Substituting corn silage with brown midrib dwarf pearl millet silage at 10% of the diet dry matter supported high milk production in dairy cows. When planning on farm forage production strategies, brown midrib dwarf pearl millet should be considered as a viable fiber source.     

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 × 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, from most to least effective, was in the order CM > SSBM > CSM.     

Effects of timing of palmitic acid supplementation on production responses of early-lactation dairy cows

The objective of our study was to evaluate the effects of timing of palmitic acid (C16:0) supplementation on production responses of early-lactation dairy cows. Fifty-two multiparous cows were used in a randomized complete block design experiment. During the fresh period (FR; 1–24 d in milk) cows were assigned to either a control diet containing no supplemental fat (CON) or a diet supplemented with C16:0 (palmitic acid, PA; 1.5% of diet dry matter). During the peak (PK) period (25–67 d in milk) cows were assigned to either a CON diet or a PA (1.5% of diet dry matter) diet in a 2 × 2 factorial arrangement of treatments considering the diet that they received during the FR period. During the FR period, we did not observe treatment differences for dry matter intake or milk yield. Compared with CON, PA increased the yield of 3.5% fat-corrected milk by 5.30 kg/d, yield of energy-corrected milk (ECM) by 4.70 kg/d, milk fat content by 0.41% units, milk fat yield by 280 g/d, and protein yield by 100 g/d. The increase in milk fat associated with the PA treatment during the FR period occurred due to an increase in yield of 16-carbon milk fatty acids (FA) by 147 g/d (derived from both de novo synthesis and extraction from plasma) and preformed milk FA by 96 g/d. Compared with CON, PA decreased body weight (BW) by 21 kg and body condition score (BCS) by 0.09 units and tended to increase BW loss by 0.76 kg/d. Although PA consistently increased milk fat yield and ECM over time, a treatment × time interaction was observed for BW and BCS due to PA inducing a greater decrease in BW and BCS after the second week of treatments. Feeding PA during the PK period increased milk yield by 3.45 kg/d, yield of 3.5% fat-corrected milk by 4.50 kg/d, yield of ECM by 4.60 kg/d, milk fat content by 0.22% units, milk fat yield by 210 g/d, protein yield by 140 g/d, and lactose yield by 100 g/d but tended to reduce BW by 10 kg compared with CON. Also, during the PK period we observed an interaction between diet fed in the FR and PK periods for milk fat yield due to feeding PA during the PK period increasing milk fat yield to a greater extent in cows that received the CON diet (+240 g/d) rather than the PA diet (+180 g/d) during the FR period. This difference was associated with the yield of preformed FA because feeding PA during the PK period increased the yield of preformed milk FA only in cows that received the CON diet during the FR period. In conclusion, feeding a C16:0 supplement to early-lactation cows consistently increased the yield of ECM in both the FR and PK periods compared with a control diet. For some variables, the effect of feeding C16:0 was affected by timing of supplementation because milk yield increased only during the PK period and BW decreased to a greater extent in the FR period. Regardless of diet fed in the FR period, feeding a C16:0 supplement during the PK period increased yields of milk and milk components.     

Field bean inclusion in the diet of early-lactation dairy cows: Effects on performance and nutrient utilization

The European livestock sector has a significant deficit of high-quality protein feed ingredients. Consequently there is interest in using locally grown protein grain crops to partially or completely replace imported protein feeds in dairy cow rations. Field bean (FB; Vicia faba) has been identified as a locally grown crop with significant potential. The current study was designed to examine the effects of FB on cow performance and nutrient utilization in the diet of early-lactation dairy cows, including high levels of FB (up to 8.4 kg/cow per day). The experiment used 72 dairy cows in a 3-treatment continuous design (from calving until wk 20 of lactation). All cows were given ad libitum access to a mixed ration comprising grass silage and concentrates [45:55 on a dry matter (DM) basis]. Concentrates offered contained either 0, 349, or 698 g of FB/kg of concentrate (treatments FB0, FB-Low, and FB-High, respectively), with FB completely replacing soybean meal, rapeseed meal, maize gluten, and wheat in the concentrate for the FB-High treatment. Following completion of the 20-wk experiment, ration digestibility, nutrient utilization, and methane (CH₄) production were measured using 4 cows from each treatment. Neither silage DM intake, total DM intake, nor milk yield were affected by treatment. Cows on FB0 had a higher milk fat content than those on FB-High, and cows on FB0 and FB-Low had higher milk protein contents than did those on FB-High. Field bean inclusion increased the degree of saturation of milk fat produced. Milk fat yield, milk protein yield, and milk fat plus protein yield were higher with FB0 than with either FB-Low or FB-High. Treatment had no effect on the digestibility of DM, organic matter, nitrogen (N), gross energy, or neutral detergent fiber, whereas digestibility of acid detergent fiber was higher with FB0 than with FB-High. Neither the efficiency of gross energy or N utilization, nor any of the CH₄ production parameters examined, were affected by treatment. Similarly, none of the fertility or health parameters examined were affected by treatment. The reduction in milk fat observed may have been due to the higher starch content of the FB-High diet, and the reduction in milk protein may have been due to a deficit of methionine in the diet. It is likely that these issues could be overcome by changes in ration formulation, thus allowing FB to be included at the higher range without loss in performance.     

Influence of formaldehyde-treated soybean meal on milk production

Forty-eight Holstein cows were fed one of four diets containing 12.5% crude protein (negative control); 15.5% crude protein with untreated soybean meal; 15.5% crude protein with formaldehyde (.3%)-treated soybean meal; or 18% crude protein (positive control). Diets were 60% concentrate, 22% corn silage, 14% alfalfa hay, and 4% beet pulp (dry matter). Data were collected during the first 200 d of lactation. Dry matter intake, milk, and milk component yields did not differ among cows fed the untreated soybean meal, treated soybean meal, and positive control diets. Cows fed negative control diet consumed less dry matter and produced less milk than cows fed the other diets. Milk protein yield was lower for cows fed the negative control diet compared with the other diets. Nonprotein nitrogen content of milk increased as dietary protein increased.     

Effects of replacing wheat starch with glycerol on methane emissions,milk production,and feed efficiency in dairy cows fed grass silage-based diets

To lower the effect of climate change from cattle production, we should aim at decreasing their enteric methane emissions per kilogram of milk or meat. Glycerol may be absorbed through the rumen epithelium and would consequently be less available to microbes in the rumen. Glycerol could thus supply dairy cows with energy for milk production without contributing much to methane production. This study evaluated the effect of replacing wheat starch with glycerol on milk production, feed intake, and methane emissions. Twenty-two Swedish Red cows in mid lactation were used in a switch-back, change-over experiment with 3 periods of 21 d. The 2 dietary treatments consisted of a total mixed ration based on (g/kg of dry matter) grass silage (605), rapeseed meal (120), and barley (70) and either wheat starch or refined glycerol (200) fed ad libitum. The glycerol diet resulted in higher dry matter intake (21.6 vs. 20.1 kg/d) and methane emissions (482 vs. 423 g/d) compared with the diet containing wheat starch, whereas no difference was found in energy-corrected milk yield (28.4 vs. 29.7 kg/d). These results indicate that when glycerol is mixed with the feed, it is available to rumen microbes to a larger extent than initially assumed. Compared with wheat starch, adding refined glycerol (200 g/kg of dry matter) to the feed of dairy cows does not seem to have the potential to decrease enteric methane emissions.     

Effect of dietary fat supplementation on methane emissions from dairy cows fed wheat or corn

Diets that contain high proportions of either wheat or supplementary fat have been individually reported to reduce enteric methane production. The objective of this research was to determine the effect of dietary fat supplementation on methane emissions and milk yield from cows fed diets containing either corn or wheat grains. It was hypothesized that cows fed a diet containing wheat would produce less methane and have lower methane yield (methane per kg of dry matter intake; MY) than cows fed a diet containing corn and that methane mitigation from fat supplementation would occur irrespective of the type of grain in the basal diet. The experiment involved 32 Holstein-Friesian dairy cows allocated to 1 of 4 treatment groups (n = 8) and individually fed different diets restricted to approximately 90% of their mean ad libitum intake measured during a covariate period. All animals were offered 11.5 kg of dry matter/d of alfalfa hay, 1.8 kg of dry matter/d of solvent-extracted canola meal, and 1 of 4 dietary supplements. Dietary supplements were 8 kg of dry matter/d of either corn or wheat, or these same treatments with the addition of 0.8 kg of canola oil. In this 5-wk experiment, d 1 to 7 served as the covariate period, d 8 to 14 as the transition period, d 15 to 28 as the adaptation period, and d 29 to 35 as the experimental period. Cows were fed their full treatment diets from d 15 to 35 during which time milk production and feed intake were measured daily. During d 29 to 35, methane production was measured for individual cows daily using the sulfur hexafluoride tracer method. The resulting averages for milk production and feed intake were analyzed by analysis of covariance with factorial grain by fat as treatment structure, animal as the unit within blocks, and the corresponding milk production or feed intake covariate averages as principal covariate. Data on milk fatty acids, ruminal fluid data on pH, ammonia, volatile fatty acids, protozoa, and methane were analyzed by ANOVA using the same treatment and blocking structures excluding the principal covariate. Cows fed a diet containing wheat had greater MY than cows fed a diet containing corn. Irrespective of the type of grain in the diet, increasing the fat concentration from 2 to 6% dry matter reduced MY. It is concluded that the grain component in the basal diet does not affect the mitigating effects of dietary fat supplements on MY.     

Effect of substituting soybean meal and canola cake with grain-based dried distillers grains with solubles as a protein source on feed intake,milk production,and milk quality in dairy cows

The growth of the bioethanol industry is leading to an increase in the production of coproducts such as dried distillers grains with solubles (DDGS). Both corn-based DDGS and grain-based DDGS (gDDGS; defined as originating from grain sources such as barley, wheat, triticale, or a mix, excluding corn) appear to be relevant sources of feed and protein for dairy cows. To date, most of the studies investigating DDGS have been performed with corn-based DDGS. The objectives of this study were to determine the effects of the proportion of gDDGS in the diet on feed intake, milk production, and milk quality. The present experiment involved 48 Holstein cows in a replicated 3 × 3 Latin square design with 3 grass-based dietary treatments consisting of 4, 13.5, and 23% gDDGS on a dry matter (DM) basis (L, M, and H, respectively) as a replacement for a concentrate mix. The concentrate mix consisted of soybean meal, canola cake, and beet pulp. Dry matter intake and energy-corrected milk yield were not affected by the proportion of gDDGS in the diet. Daily milk yield decreased with the H diet compared with the L and M diets. The percentage of fat in milk was higher when cows were fed the H diet compared with the L and M diets, whereas milk fat yield was not affected by dietary treatment. The M diet had a higher percentage of protein in milk compared with the L and H diets. Milk protein yield was similar for the L and M diets; however, it decreased for the H diet. Milk taste was not affected by the proportion of gDDGS in the diet or when milk was stored for 7 d. Linoleic acid and conjugated linoleic acid cis-9,trans-11 in milk increased with increasing proportion of gDDGS. To conclude, gDDGS can replace soybean meal and canola cake as a protein source in the diet of dairy cows. Up to 13.5% of the diet may consist of gDDGS without negatively affecting milk production, milk quality, or milk taste. When gDDGS represents 23% of dietary DM, milk production is reduced by 1.6 kg/d, whereas energy-corrected milk production is numerically reduced by 1 kg.     

Replacing soybean meal with okara meal: Effects on production,milk fatty acid and plasma amino acid profile,and nutrient utilization in dairy cows

Okara meal is a byproduct from the production of soymilk and tofu and can potentially replace soybean meal (SBM) in dairy diets due to its high crude protein (CP) concentration and residual fat. The objective of this study was to investigate the effects of replacing SBM with okara meal on feed intake, yields of milk and milk components, milk fatty acid (FA) profile, nutrient utilization, and plasma AA concentration in lactating dairy cows. Twelve multiparous (65 ± 33 d in milk) and 8 primiparous (100 ± 35 d in milk) organically certified Jersey cows were paired by parity or days in milk, and within pair, randomly assigned to treatments in a crossover design with 21-d periods (14 d for diet adaptation and 7 d for data and sample collection). Diets were fed as total mixed ration formulated to be isonitrogenous and isofibrous and contained (dry matter basis) 50% mixed, mostly grass baleage, 2% sugarcane liquid molasses, 2% minerals-vitamins premix, and either (1) 8.1% SBM, 10% soyhulls, and 27.9% ground corn (CTRL); or (2) 15% okara meal, 8% soyhulls, and 23% ground corn (OKR). Dietary CP, ash-free neutral detergent fiber, and total FA averaged 15.4, 35.3, and 3.08% for CTRL and 15.9%, 36.3%, and 3.74% for OKR, respectively. Substitution of SBM with okara meal did not alter dry matter intake but increased intakes of CP and ash-free neutral detergent fiber. Additionally, no significant differences between treatments were observed for yields of milk and milk components, and concentrations of milk fat, lactose, and total solids. However, milk true protein concentration was lower in cows fed OKR (3.76%) versus CTRL (3.81%). Both milk urea N (8.51 vs. 9.47 mg/dL) and plasma urea N (16.9 vs. 17.8 mg/dL) concentrations decreased with OKR relative to the CTRL diet, respectively. Compared with CTRL, feeding OKR lowered the milk proportions of total odd-chain FA, de novo FA, and mixed FA and increased those of preformed FA, total n-6 FA, and total n-3 FA. The milk proportions of trans-10 18:1, trans-11 18:1, and cis-9,trans-11 18:2 were greater with feeding OKR versus the CTRL diet. The apparent total-tract digestibility of nutrients, urinary excretion of total purine derivatives (uric acid plus allantoin), and total N were not affected by treatments. Except for plasma Leu, which was lower in OKR compared with the CTRL diet, no other significant changes in the plasma concentrations of AA were observed. The plasma concentration of carnosine was lowest in cows receiving the OKR diet. Overall, our results revealed that okara meal can completely replace SBM without negatively affecting production and nutrient digestibility in early- to mid-lactation Jersey cows. Further research is needed to assess the economic feasibility of including okara meal in dairy diets, as well as the amount of okara meal that maximizes yields of milk and milk components in dairy cows in different stages of lactation.