Hay Crop Silage Research Articles

IN VITRO PROTEIN SOLUBILITY AND SOLUBILIZATION OF SELECTED FEEDSTUFFS FOR RUMINANT FEEDING

Protein solubility in mineral buffer, and protein degradability with bacterial protease, of condensed distillers solubles, distillers dried grains, brewers dried grains, raw, roasted and extruded soybeans, corn silage, haycrop silage, hay, corn gluten feed, multiage solulac and lactosy-urea (Ewoplus) were in­vestigated for use in ruminant feeding. The proteins of distillers dried grains, brewers dried grains, roasted and extruded soybeans and corn gluten meal were highly Insoluble in mineral buffer with average solubilities of 4.50%, 10.47%, 8.07%, 13.12% and 5.40% respectively. Lactosyl­urea (Ewoplus) was 100% soluble. The protease of streptomyces griseus was used to determine protein degradability. The degradable proteins of distillers grains, brewers grains, raw and roasted soybeans, and corn gluten meal were resis­tant to protease action. Extruded soybeans, distillers solubles, forage feedstuffs and Ewoplus were readily degradable.

Influence of a novel bm3 corn silage hybrid with floury kernel genetics on lactational performance and feed efficiency of Holstein cows

Dry matter intake, lactation performance, and chewing behavior of multiparous Holstein cows (n = 15) fed diets containing a novel bm3 corn silage hybrid with floury kernel genetics were compared with cows fed diets containing commercially available conventional and bm3 hybrids using a replicated 3 × 3 Latin square design with 28-d periods. Cows were housed in tiestalls, milked 3 times/d, and fed a total mixed ration containing 49.0% (dry matter basis) of (1) a conventional corn silage hybrid (CONV); (2) a brown midrib bm3 hybrid (BMR); or (3) a bm3 hybrid with floury kernel genetics (BMRFL). All diets contained 6.3% hay crop silage and 44.7% concentrate. Dietary nutrient composition averaged 32.7% neutral detergent fiber (NDF) and 26.3 starch (% of dry matter). Data were analyzed by ANOVA using the MIXED procedure in SAS (SAS Institute Inc., Cary, NC). The dry matter intake was greater for cows fed BMR (28.0 kg/d) compared with CONV (26.8 kg/d), whereas dry matter intake for cows fed BMRFL was intermediate (27.6 kg/d). Energy-corrected milk (ECM) yield was greater for cows fed BMR (50.3 kg/d) and BMRFL (51.8 kg/d) compared with CONV (47.2 kg/d). Milk fat yield was higher for cows fed BMRFL (1.87 kg/d) compared with CONV (1.74 kg/d) and BMR (1.80 kg/d). Milk protein yield was greater for cows fed BMR (1.49 kg/d) and BMRFL (1.54 kg/d) compared with CONV (1.36 kg/d). Milk urea-N was reduced for cows fed BMR (11.61 mg/dL) and BMRFL (11.16 mg/dL) compared with CONV (13.60 mg/dL). Feed efficiency (ECM/dry matter intake) was higher for cows fed BMRFL (1.87) compared with CONV (1.76) and BMR (1.79). Milk N efficiency was greatest for cows fed BMRFL (40.4%) followed by BMR (38.1%) and finally CONV (35.3%). Cows fed CONV chewed 5 min more per kilograms of NDF consumed than cows fed either of the BMR hybrids. No differences were observed among diets in apparent total-tract digestibility of NDF (58.1%) or starch (99.3%). Overall lactational performance was enhanced for cows fed diets containing both BMR and BMRFL hybrids versus CONV. In addition, feeding the BMRFL corn silage improved efficiency of component-corrected milk production and milk N efficiency compared with the CONV and BMR silages.

Okara as a protein supplement affects feed intake and milk composition of ewes and growth performance of lambs.

Evaluating the feeding value of wet okara as a protein supplement for lactating ewes with twin lambs was the objective. A 4 × 4 Latin square replicated 2× (4 sheep, 4 treatments, 4 periods per square; 2 squares) was conducted to examine the influence of concentrate mix (okara or not) and type of forage (silage or hay) on ewe milk composition and growth of their lactating lambs. Treatment periods were 14 days (7 days adaptation and 7 days collection). Ewes (55 to 74.8 kg BW) were fed 1 of 4 diets: wheat middling and corn concentrate with mixed grass hay (TSH), okara and corn with mixed grass hay (OSH), soybean and wheat middlings with hay crop silage (TSS), and okara and corn with hay crop silage (OSS). Ewes fed hay diets had lower forage dry matter intakes than ewes fed silage. Intake of okara supplement was higher (P < 0.05) with OSH (3.64 kg/d) than with OSS (1.70 kg/d). There was no difference in supplement intake between TSH and TSS. There were no differences among diets for lamb daily gains or in ewe milk compositions among the diets. Okara is an effective source of protein for lactating ewes and their twin lambs.

Partitioning variation in nutrient composition data of common feeds and mixed diets on commercial dairy farms

A large project involving commercial dairy farms was undertaken to identify important sources of variation in composition data of common feeds and mixed diets. This information is needed to develop appropriate sampling schedules for feeds and should reduce the uncertainty associated with the nutrient composition of delivered diets. The first subproject quantified sources of variation in the composition of corn and haycrop silages over a 2-wk period. Silages from 11 commercial dairy farms in Ohio and Vermont were sampled daily over a 14-d period. Most silages were sampled in duplicate each day, and all samples were assayed in duplicate. Total variance was partitioned into analytical, sampling, farm, and true day-to-day components. Farm was the largest source of variation, but within-farm variance was our primary interest. Sampling variance comprised 30 to 81% of within-farm variance depending on nutrient and type of silage. For dry matter, true day-to-day variation was the greatest source of variance, but for most other nutrients, sampling was the largest source of within-farm variation. The second subproject consisted of sampling feeds and total mixed rations (TMR) from 47 commercial dairy farms across the United States. Feeds and TMR were sampled monthly. Because samples were not assayed in duplicate, source of variation included farm, month, and residual (sampling plus analytical). For corn and alfalfa silages, month-to-month variation over a 12-mo period comprised about twice as much of the total within-farm variation as did day-to-day variation over a 14-d period in the first subproject. Although month-to-month variation was greater than sampling variation, sampling still accounted for 9 to 37% of the total within-farm variance for those 2 feeds. For TMR, sampling plus analytical variance accounted for approximately 40 to 70% of the total within-farm variance (depending on the nutrient). Variance components were estimated for several nutrients and for several common feeds. The contributions to total variance differed depending on feed and nutrient, but the information provided will help in determining whether on-farm samples should be taken and if so, how often. A major implication of this project is that sampling is a substantial source of variation in silages, concentrates, and TMR, and data from a single sample are likely not highly reliable.

Effects of corn-based reduced-starch diets using alternative carbohydrate sources on performance of lactating Holstein cows

Increases in grain prices have led to renewed interest in feeding reduced-starch diets to lactating dairy cows. An experiment was conducted to determine the effects of altering carbohydrate sources and reducing dietary starch on lactational performance, feeding behavior, and ruminal measures of Holstein dairy cows. Fifteen multiparous cows (6 ruminally cannulated) were blocked and assigned to 1 of 5 squares and used in a replicated 3×3 Latin square design with 21-d periods. Cows were fed 1 of 3 experimental diets: a control diet containing 20% brown midrib corn silage, 20% conventional corn silage, and 10% hay crop silage (CON); a reduced-starch high-forage diet containing 53% brown midrib corn silage and 10% hay crop silage (HFOR); and a reduced-starch diet containing the same forages as CON with partial replacement of corn meal by nonforage fiber sources (HNFFS). The CON diet contained (% of dry matter) 26.0% starch and 34.7% neutral detergent fiber (NDF), whereas the HFOR and HNFFS diets contained 21.4 or 21.3% starch and 38.3 or 38.0% NDF, respectively. Dry matter intake tended to be greater for cows fed the CON diet (28.2kg/d) compared with those fed the HFOR diet (27.2kg/d). Dry matter intake for cows fed the HNFFS diet was intermediate (27.7kg/d). Milk yield was greater for cows fed the CON diet (51.6kg/d) compared with those fed the HFOR diet (48.4kg/d), but milk fat content tended to increase for cows fed the HFOR diet (3.98%) compared with those fed the CON diet (3.66%). Consequently, fat-corrected and solids-corrected milk yields were unaffected by dietary treatments. Total chewing, eating, and rumination times were similar across all dietary treatments. Rumination time per kilogram of DM was greatest for the HFOR diet, intermediate for the HNFFS diet, and least for the CON diet, whereas rumination time per kilogram of NDF was greatest for the CON diet and least for the HNFFS diet. Mean ruminal pH, NH3-N (mg/dL), and total volatile fatty acid concentrations (mM) were similar across all dietary treatments. Molar proportion of ruminal acetate (mol/100mol) was increased for cows fed the HFOR diet compared with cows fed the CON diet. Microbial N yield measured by urinary purine derivatives was unaffected by dietary treatment. Reduced-starch diets containing greater amounts of high quality, highly digestible forage or nonforage fiber sources in place of corn meal resulted in similar fat-corrected or solids-corrected milk yield for high-producing dairy cows in the short term.

Effect of reducing dietary forage in lower starch diets on performance, ruminal characteristics, and nutrient digestibility in lactating Holstein cows

This experiment evaluated the effect of feeding a lower starch diet (21% of dry matter) with different amounts of forage (52, 47, 43, and 39% of dry matter) on lactational performance, chewing activity, ruminal fermentation and turnover, microbial N yield, and total-tract nutrient digestibility. Dietary forage consisted of a mixture of corn and haycrop silages, and as dietary forage content was reduced, chopped wheat straw (0–10% of dry matter) was added in an effort to maintain chewing activity. Dietary concentrate was adjusted (corn meal, nonforage fiber sources, and protein sources) to maintain similar amounts of starch and other carbohydrate and protein fractions among the diets. Sixteen lactating Holstein cows were used in replicated 4×4 Latin squares with 21-d periods. Dry matter intake increased while physically effective neutral detergent fiber (peNDF1.18) intake was reduced as forage content decreased from 52 to 39%. However, reducing dietary forage did not influence milk yield or composition, although we observed changes in dry matter intake. Time spent chewing, eating, and ruminating (expressed as minutes per day or as minutes per kilogram of NDF intake) were not affected by reducing dietary forage. However, addition of chopped wheat straw to the diets resulted in greater time spent chewing and eating per kilogram of peNDF1.18 consumed. Reducing dietary forage from 52 to 39% did not affect ruminal pH, ruminal digesta volume and mass, ruminal pool size of NDF or starch, ruminal digesta mat consistency, or microbial N yield. Ruminal acetate-to-propionate ratio was reduced, ruminal turnover rates of NDF and starch were greater, and total-tract digestibility of fiber diminished as dietary forage content decreased. Reducing the dietary forage content from 52 to 39% of dry matter, while increasing wheat straw inclusion to maintain chewing and rumen function, resulted in similar milk yield and composition although feed intake increased. With the lower starch diets in this short-term study, the minimal forage content to maintain lactational performance was between 39 and 43%.

Effects of Feeding Formate-Treated Alfalfa Silage or Red Clover Silage 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 blocked by days in milk and randomly assigned to replicated 4×4 Latin squares to quantify effects of nonprotein N (NPN) content of alfalfa silage (AS) and red clover silage (RCS) on omasal nutrient flows. Diets, fed as total mixed rations, contained 50% dry matter from control AS (CAS), ammonium tetraformate-treated AS (TAS), late maturity RCS (RCS1), or early maturity RCS (RCS2). Silages differed in NPN and acid detergent insoluble N (% of total N): 50 and 4% (CAS); 45 and 3% (TAS); 27 and 8% (RCS1); 29 and 4% (RCS2). The CAS, TAS, and RCS2 diets had 36% high-moisture shelled corn and 3% soybean meal, and the RCS1 diet had 31% high-moisture shelled corn and 9% soybean meal. All diets contained 10% corn silage, 27% neutral detergent fiber, and 17 to 18% crude protein. Compared with RCS, feeding AS increased the supply of rumen-degraded protein and omasal flows of nonammonia N and microbial protein, which may explain the improved milk yield observed in the companion lactation trial. However, omasal flow of rumen-undegraded protein was 34% greater on RCS. Except for Arg, omasal flows of individual AA, branched-chain AA, nonessential AA, essential AA, and total AA did not differ between cows fed AS vs. RCS. Within AS diets, no differences in omasal AA flows were observed. However, omasal flows of Asp, Ser, Glu, Cys, Val, Ile, Tyr, Lys, total nonessential AA, and total AA all were higher in cows fed RCS1 vs. cows fed RCS2. In this trial, there was no advantage to reducing NPN content of hay-crop silage.

Effects of Maturing Stage of Corn Hybrids on Silage Yield, Feeding Value for Dairy Cows and Milk Production in a Cold Region of Japan

This experiment was conducted to evaluate the effects of differently maturing corn hybrids on silage production and milk production per unit area in the northern part of Japan, where grain development occurs under decreasing ambient temperature. Both hybrids were harvested at the same time. The stages of maturity for the early-maturing hybrids (EH; 80 d relative maturity) and the midmaturing hybrids (MH; 93 d relative day) were early dent and late dough stage, respectively. The plant yields for MH were higher than those for EH. The dry matter (DM) content of MH was lower than that for EH, and the effluent loss for MH silage was greater than that for EH silage. Therefore, the DM yields of prepared silage per area were similar for both treatments. Twelve multiparous mid-lactation Holstein cows (58±13 days in milk) were fed diets based on EH or MH silage in a crossover design with two 3-week periods. Cows were fed 3 kg of hay crop silage (DM basis) and either EH or MH silage ad libitum, and concentrates were supplied to meet NRC requirement for dairy cows. Silage DM intake for EH was found to be higher (p<0.05) than that for MH (10.0 vs. 9.1 kg/day). Milk production and milk composition for EH were similar to those for MH. Feed efficiency per total feed intake was similar in both treatments, although the feed efficiency per concentrate intake tended to be higher for the EH than that for the MH diet. These results indicate that differences in maturation in corn hybrids affect the effluent production of silage and the silage intake of dairy cows. It may be advantageous to plant early hybrid corn with a reduction in effluent production of silage as well as a reduction in purchased feed costs for dairy cows under the climatic conditions of the northern part of Japan.

Bag Silo Densities and Losses

Bag silos made at three research farms in 2000 and 2001 were monitored at filling and emptying to determine densities and losses. A total of 47 bags (23 alfalfa, 1 red clover, 23 whole-plant corn) were made, and losses were calculated on 39 of the silos. Dry matter (DM) density ranged from 160 to 270 kg/m3. Dry matter density increased with DM content in hay crop silages on average 2.9 kg/m3-% DM, whereas the effect in corn silage varied by bagging machine. Density decreased with increasing particle size at 4.1 kg DM/m3 per mm. The operator and the bagging machine setup both affected density. A wide range (0% to 40%) of DM losses was observed. Average DM losses were 9.2% invisible plus uncollected losses and 5.4% spoilage losses, for a total loss of 14.6%. Six silos had excessive spoilage losses of more than 15% and total losses above 25% due to plastic integrity issues or overly dry silage (>40% DM) being fed out in warm weather. Invisible losses were reduced in high-porosity silages (where spoilage losses were exacerbated), greater in warm weather, and affected by emptying procedures. Spoilage losses in bags without plastic integrity issues were greater in dry silages, from emptying silos in warm weather, at lower feed-out rates, in bags stored for a long time, and if bags were emptied periodically rather than daily.

Ruminal pH and Digestibility Profiles During the Transition Period of the Dairy Cow

Three ruminally cannulated cows calving within 10 d of each other were fitted with indwelling ruminal pH probes 3 wk prior to expected calving dates. They were used to evaluate diurnal variation in ruminal pH pre- and post-partum and to determine the influence of daily high and low pH levels on ruminal digestion of feedstuffs. Each probe was connected to a data logger, and hourly measurements were made from 3 wk prepartum through 7 wk postpartum. Cows pre- and postpartum were fed a total mixed ration (TMR) once daily. In situ digestion of corn silage, haylage, and corn meal DM was determined for 6h prior to feeding (high pH) and then starting at 3h and continuing through 9h after feeding (low pH) for one week prior to expected calving date and for 1 and 3 wk postpartum. Weekly mean low pH was greater for cows during the prepar-tum period than during the postpartum period. There was a negative relationship between mean weekly low pH and time. Area under the curve for pH < 6 and 5.5 increased from -3 to 7 wk postpartum. In situ digestion of corn silage and haycrop silage was not affected by time pre- or postpartum or by ruminal pH. Corn meal digestion at 6h was higher at wk 1 prepartum than at wk 1 and 3 postpartum. Corn meal digestion was depressed by lower rather than higher ruminal pH. This study illustrates that there is a linear depression in ruminal pH starting 3 wk prepartum through 7 wk postpartum, suggesting that dairy cattle have a greater propensity for acidosis postpartum as intake increases. In addition, periods of low pH depressed digestibility of corn meal but not hay crop or corn silage, which suggests that energy availability may be lower.

Influence of particle size on the effectiveness of the fiber in corn silage.

This experiment evaluated the influence of particle size on the effectiveness of fiber in corn silage relative to that in hay crop, which consisted of mostly alfalfa silage. Fifteen multiparous Holstein cows were assigned to five treatments in each of 2 yr. The design was replicated but truncated 5 x 5 Latin squares with three 21-d periods in 1994 and four 21-d periods in 1995. The five diets (2-yr average, dry basis) were a basal, low fiber control with 12% neutral detergent fiber (NDF) from hay crop forage (60% of total diet NDF); a high fiber control with 22% NDF from hay crop forage (82% of total diet NDF); and three diets each containing 12% NDF from hay crop forage and 9% NDF from coarse corn silage, fine corn silage, or an equal mixture of the two. An increase in the forage content above the basal amount with either hay crop or corn silage increased rumination and total chewing time. No detectable differences in rumination, total chewing time, or milk fat concentration were detected among the corn silage diets. In yr 1, yield of milk components and dry matter intake were greater for cows fed the four low alfalfa diets, but there was no effect due to particle size of the corn silage. In yr 2, linear increases in milk, fat, and protein yields were observed as the mean particle size of the corn silage decreased. Reduction of corn silage particle size did not affect chewing behavior.

A Simple Method for the Analysis of Particle Sizes of Forage and Total Mixed Rations

A simple separator was developed to determine the particle sizes of forage and TMR that allows for easy separation of wet forage into three fractions and also allows plotting of the particle size distribution. The device was designed to mimic the laboratory-scale separator for forage particle sizes that was specified by Standard S424 of the American Society of Agricultural Engineers. A comparison of results using the standard device and the newly developed separator indicated no difference in ability to predict fractions of particles with maximum length of less than 8 and 19mm.The separator requires a small quantity of sample (1.4L) and is manually operated. The materials on the screens and bottom pan were weighed to obtain the cumulative percentage of sample that was undersize for the two fractions. The results were than plotted using the Weibull distribution, which proved to be the best fit for the data.Convenience samples of haycrop silage, corn silage, and TMR from farms in the northeastern US were analyzed using the forage and TMR separator, and the range of observed values are given.

Full Lactation Response of Cows Fed Diets with Different Sources and Amounts of Fiber and Ruminal Degradable Protein

Twenty Holstein cows were fed diets based on a mix of haycrop silage (immature orchardgrass or immature alfalfa) and corn silage with a conventional concentrate (primarily ground ear corn and soybean meal) or a concentrate based on by-products (primarily soyhulls, fish meal, and corn gluten meal). Diets for periods 1 (7 to 134 DIM), 2 (135 to 234 DIM), and 3 (235 to 305 DIM) were 40: 10:50, 40:20:40, and 40:30:30 haycrop si1age:corn si1age:concentrate (DM basis), respectively. Dietary NDF ranged from 33 to 45%. The species of haycrop forage fed in combination with corn silage did not greatly affect milk production (mean = 28 kg/d), milk composition, nutrient digestibility, or DMI (expressed on a BW basis). Cows fed alfalfa gained more BW than those fed orchardgrass (.18 vs. .03 kg/d). Cows fed by-products produced similar amounts of milk, more milk fat (1.1 vs. .9 kg/d), and had higher DMI (21.4 vs. 19.6 kg/d) but lower BW gains (.03 vs. .18 kg/d) than those fed conventional concentrate. These data showed that a mix of high quality orchardgrass and corn silage is acceptable for dairy cows and that supplementation strategies are similar for diets based on orchardgrass and those based on alfalfa.

Influence of roughage and grain processing in high-concentrate diets on the performance of long-fed Holstein steers.

The effects of roughage source and timing of inclusion in high-concentrate diets on feedlot performance were evaluated in each of 2 yr with 144 and 120 long-fed Holstein steers, respectively. Roughage, when included in the diet, was delivered in a built-in-roughage (BIR) pellet supplying 15 and 6% roughage (percentage of DM) or hay crop silage (HCS) supplying 7 and 10% roughage (percentage of DM) for the growing and finishing periods, respectively. The six dietary treatments (two pens each) investigated were continuous whole corn and pelleted supplement (no added roughage; WSC-PEL); BIR with cracked corn either in the growing (BIR-G) or finishing (BIR-F) period with whole corn being fed with pelleted supplement when BIR was not part of the diet; BIR and cracked corn fed continuously (BIR-CONT); and two HCS treatments in which the corn was fed either whole (HCS-WSC) or cracked (HCS-CSC) for the entire feeding period. Replicates were slaughtered 4 and 3 wk apart for yr 1 and 2, respectively. Pooled daily gains (yr 1 and 2) for the entire trial (1.39 to 1.45 kg/d) were not different (P > .05). Daily DM and concentrate intakes were lower (P < .001) and gain efficiency was higher (P < .001) for the WSC-PEL than for the other treatments. Carcass characteristics were similar among treatments except for an improved yield grade (P < .02) for the HCS treatments over the BIR treatments. The WSC-PEL treatment was the most profitable (+/steer) and the BIR-CONT diet was the least profitable. The HCS treatments were the most profitable of the roughage treatments. A newly proposed intake prediction equation for feedlot cattle performed similarly to the 1984 NRC equation with long-fed Holstein steer calves.

Effects of Enzyme-Inoculant Systems on Preservationand Nutritive Value of Haycrop and Corn Silages

Third-crop mixed grass-legume forage and corn were ensiled in 70-tonne bunker silos to evaluate the effects of a commercial carbohydrase enzyme-inoculant mixture (220 ml/tonne) and an experimental enzyme-inoculant mixture (264 ml/tonne) on silage fermentation and composition, ruminal degradation, and milk production. Twelve Jersey and 24 Holstein early lactation cows were fed one of four TMR at 32.5:32.5:35.0 haycrop silage:corn silage:concentrate (DM basis) containing a combination of treated and untreated silages from d 2 to 100 of lactation. Bunker silages were incubated twice in situ in fistulated cows in each dietary treatment to determine rates of DM and NDF degradation. Treatment of haycrop silage significantly reduced silage pH and acetic acid concentration and increased titratable acidity, lactic acid concentration, lactate: acetate ratio, and DM and NDF disappearances after 24h of ruminal incubation. Treated haycrop silage increased DMI:BW ratio and daily production of milk, milk protein, and SNF of early lactation cows. Application of the experimental mixture to corn silage did not change silage fermentation or composition, except that the concentration of NH3 was reduced. Enzyme-treated corn silage did not improve DMI and slightly reduced daily milk production in early lactation cows.

Dietary Protein Degradability Effects on Plasma and Milk Urea Nitrogen and Milk Nonprotein Nitrogen In Holstein Cows

Fifteen multiparous, midlactation Holstein cows were used in a 5 × 5 Greco-Latin square to investigate the effects of various amounts of ruminally degradable and undegradable protein on plasma urea and milk urea N and NPN constituents. Diets were designed to provide the following percentage of degradable and undegradable protein relative to NRC requirements: diet A, 80, 80%; diet B, 100, 100%; diet C, 120, 80%; diet D, 100, 120%; and diet E, 120, 120%. All cows were fed for ad Libitum intake a TMR consisting of 47% corn silage, 18% haycrop silage, and 35% concentrate (DM basis). Concentrate consisted of various amounts of dry corn plus soybean, fish, and blood meals to alter the degradability of protein. In situ measurements were used to determine grain protein degradability. Plasma urea N was increased across diets A to E, respectively: 8.2, 14.8, 16.5, 17.8, and 20.7 mg/dl. The within-cow coefficient of correlation between plasma and milk urea N was .88. The intake of undegradable protein elevated plasma and milk urea N to a similar extent as intake of degradable protein. Multiple regression analysis across all diets revealed a negative relationship of energy intake on plasma urea N. Diet significantly influenced milk true protein yield for diets A to E, respectively: .73, 30, .73, .78, and .81 kg/d. Milk true protein yield was influenced by milk yield, undegradable protein, and energy intake. Milk NPN concentration increased across diets A to E, respectively: 28.7, 33.9, 35.6, 36.8, and 39.8 mg/dl. The increase in milk NPN concentration across diets was attributed largely to an increase in the urea component of milk NPN.

Weekly Balancing Crude Protein in Diets for Holstein Cows Throughout Lactation Using One Versus Two Grains

Holstein cows (n = 72, 28 primiparous) were fed for ad libitum intake a forage mixture (corn and haycrop silages, 63:37 DM) and a 71:29 ratio of two grain mixtures (13.8 and 36.2% CP, DM basis) at 1 kg/2.5kg of the previous day's milk during 1 to 28 DIM (covariate period). Thereafter, rations were balanced and adjusted for energy and CP weekly based on monthly DHI data, forage analyses, and NRC requirements. Cows were blocked by parity (1 vs. >1) and assigned randomly to receive one grain (blend of 13.8 and 36.2% CP grains, herd mean) or two grains according to individual needs. Daily yields of milk, 4% FCM, SCM. and resulting intakes of grain were higher for cows fed two grains, but the increase in daily DMI and the decreases in daily forage intake and SCM:grain ratio were not significant. Fewer pluriparous cows (3 vs. 8 out of 19) on the two-grain treatment conceived after first service, but overall services per conception (1.97) were equal. Percentage of cows with SCC below linear score 4 (91%) was equal between treatments. Means adjusted by covariate 4% FCM resulted in more modest treatment effects. Advantage of two-grain versus one-grain treatment for milk per day was 7.7% for parity 1 and only 1.6% for parities >1; corresponding responses (nonsignificant) for 4% FCM were 2.8 and 4.3, respectively. Forage DMI depressions on two-grain treatment were not significant. When covariate-adjusted means were used, the advantage in income over feed cost for individualized feeding of CP was $106 and $36/yr per cow in parities 1 and >1 when cows produced 8209kg (313 DIM) and 8527kg (320 DIM) of milk, respectively.

Water Partitioning and Intake Prediction in Dry and Lactating Holstein Cows

Data from four energy and N balance trials with lactating Holstein cows (n = 329) and one trial with dry cows (n = 60) were used to predict free water intake and water-related traits. Lactating cows were between 36 and 159 DIM and, individually, were allowed ad libitum water and forage (corn silage without or with wilted haycrop silage) plus concentrates; dry cows accessed ad libitum water and single forages (grass, clover, or alfalfa, as hays or as wilted silages, or corn silage) varying in maturity. Intake of DM per day and dietary DM percentage were significant and positively related predictors of free water intake in dry and lactating cows. Daily milk yield (range 16 to 52 kg/d) was related linearly to water consumption (.60 L/kg of milk), and season effect in lactating cows was curvilinear; peak water intake was in late June and nadir in late December. Ration CP percentage (DM basis) affected free water intake only in dry cows; 1 unit of increase resulted in an increase of about 1 kg/d in water intake between 12 and 13% CP. As ration moisture dropped from 70 to 40%. free water intake increased about 7 L/d in dry cows, but this was accompanied by a drop of 15 L/d in total water intake (free plus feed water). Free water intakes were predicted with R2 of .64 and .69 in dry and lactating Holstein cows, respectively. Fecal water and urine outputs also were predicted. We found no significant relationship between DM content of the diet and the resulting ad libitum intake in either dry or lactating cows.

Influence of Intake of Rumen Undegradable Protein on Milk Production of Late Lactation Holstein Cows

Twenty Holstein cows, in late lactation, were assigned to five equal groups in an orthogonal design to determine effects of a rapidly rumen degraded protein source (canola meal) low in estimated rumen undegradable protein substituted for a slowly rumen degraded protein source (corn gluten meal) high in rumen undegradable protein on feed intake, milk production, and milk composition. Cows were fed total mixed rations based upon barley silage, haycrop silage, barley grain, and supplemental protein in three 4-wk periods, subsequent to a 4-wk covariate period. In situ rumen incubation of extreme diets and estimation of intermediate diets indicated that all diets exceeded Agricultural Research Council (United Kingdom) recommendations for rumen degradable and undegradable protein as well as NRC recommendations for rumen degradable protein. However, two to four diets, dependent upon assumed ruminal turnover rates, did not meet NRC recommendations for undegradable protein. Dry matter intake and milk yield were not influenced by substitution of canola meal with corn gluten meal to increase dietary undegradable protein content. Daily yield and milk percent of lactose, fat, and protein were not influenced by substitution. Results do not support NRC recommendations to supplement diets based upon these ensiled forages and barley grain for late lactation cows with protein sources resistent to rumen degradation. Results broadly support lower amounts of rumen undegraded protein recommended by the Agricultural Research Council.

Sodium Bicarbonate for Early Lactation Cows Fed Corn Silage or Hay Crop Silage-Based Diets

To compare the effects of NaHCO3 in diets based on different forage sources, 16 Holstein cows, in a split-plot design, were assigned at 2 d postpartum to a total mixed diet of either 30% hay crop silage:70% concentrate or 40% corn silage:60% concentrate (dry basis) that contained 0 or 1.25% NaHCO3. Over the first 6 wk postpartum, NaHCO3 increased milk fat percentage in cows fed the corn silage-based diet. During wk 2 through 6 postpartum, NaHCO3 increased milk yield with the hay crop silage-based diet and tended to decrease milk yield with the corn silage-based diet. Sodium bicarbonate increased digestion of NDF with both forages and increased excretion of urinary nitrogen with the corn silage-based diet. Responses to NaHCO3 by cows in early lactation may depend on the nature of the dietary forage component.