Production of dairy cows fed distillers dried grains with solubles in low- and high-forage diets

The objective of the study was to investigate the effects of dietary forage and distillers dried grains with solubles (DDGS) concentration on the performance of lactating dairy cows. Twelve Holstein cows were blocked by parity and milk production and assigned to replicated 4 × 4 Latin squares with a 2 × 2 factorial arrangement of treatments. Diets were formulated to contain low forage [LF; 17% forage neutral detergent fiber (NDF)] or high forage (HF; 24.5% forage NDF) and DDGS at 0 or 18% of diet dry matter. The forage portion of the diet consisted of 80% corn silage and 20% alfalfa hay (dry matter basis). A portion of the ground corn and all of the expeller soybean meal and extruded soybeans from 0% DDGS diets were replaced with DDGS to formulate 18% DDGS diets. Overall, we found no interactions of forage × DDGS concentrations for any of the production measures. We observed no effect of diet on dry matter intake. Milk yield was greater when cows were fed LF diets compared with HF diets (43.3 vs. 41.5 kg/d). Milk fat concentration (3.03 vs. 3.38%) was lower for cows fed LF diets compared with HF diets, whereas protein concentration (3.11 vs. 2.98%) and yield (1.34 vs. 1.24 kg/d) were greater for cows fed LF diets compared with HF diets. Yields of fat, total solids, energy-corrected milk, and feed efficiency were not affected by diets. Cows partitioned equally for milk, maintenance, and body reserves. Replacing starch from ground corn and protein from soybean feeds with DDGS at either 17 or 24.5% of forage NDF concentration in the diet was cost-effective and did not affect the production performance of lactating dairy cows.     

Effects of replacing chopped alfalfa hay with alfalfa silage in a total mixed ration on production and rumen conditions of lactating dairy cows

The effects of replacing chopped alfalfa hay with alfalfa silage in a total mixed ration containing barley grain and corn silage on production and rumen conditions were investigated. Cows received three diets that all contained (dry matter basis) 38.5% barley grain-based energy supplement, 30.5% corn silage, 17.0% protein supplement, and 4.2% sunflower seeds. One diet contained (dry matter basis) 9.8% of chopped alfalfa hay and no alfalfa silage. One diet contained (dry matter basis) 4.9% chopped alfalfa hay and 4.9% alfalfa silage. One diet contained (dry matter basis) 9.8% of alfalfa silage and no chopped alfalfa hay. Contents of crude protein, neutral detergent fiber, acid detergent fiber, and starch, averaged across diets, were 16.7, 41.3, 21.1, and 24.4% DM, respectively, and did not differ significantly among diets. Replacing chopped alfalfa hay with alfalfa silage decreased the proportion of dietary DM passing through the 8-mm screen of the Penn State Particle Separator from 61.9 to 55.2% dry matter and significantly increased dietary physical effective NDF (peNDF) content, calculated as the NDF retained by the two screens of the Penn State Particle Separator, from 20.1 to 23.3% DM. Replacing chopped alfalfa hay with alfalfa silage also reduced dietary DM content, increased rumen pH from 6.27 to 6.47, reduced volatile fatty acid concentrations, numerically increased milk fat concentration and milk fat yield. Milk yield, milk protein concentration, dry matter intake, and rumen ammonia concentration were not affected.     

Effect of fat from whole soybeans on performance of dairy cows fed rations differing in fiber level and particle size.

Two trials were conducted with lactating dairy cows to determine effects on intake, performance, and chewing activity of supplemental fat in early lactation diets that differed in fiber level and particle size. In trial 1, whole raw soybeans were added at 11.6% of ration DM to alfalfa silage-based TMR containing either finely chopped silage or the same silage with 8.1% coarsely chopped alfalfa hay. Each combination of soybeans (0 or 11.6%) and silage (fine or hay added) was fed as an isocaloric, isonitrogenous TMR to eight Holstein cows in early lactation in a replicated Latin square design with 4-wk periods. Addition of soybeans decreased DMI for fine silage. With silage plus hay, soybean addition decreased milk yield and protein content but increased fat test so that FCM was unchanged. Silage plus hay promoted chewing activity with no interaction of forage particle size with fat addition on chewing activity. In trial 2, TMR based on alfalfa and corn silage contained either 25 or 29% NDF and 0 or 11.6% soybeans. Otherwise, trials 1 and 2 were similar. Soybean addition decreased DMI with low NDF diets. Addition of fat from soybeans had no effect on milk yield or composition, but low fiber decreased fat test and chewing activity. When .4 to .5 kg/d of supplemental fat from whole raw soybeans was fed, higher dietary NDF and larger particle size promoted greater intake with no effect on FCM yield.     

Replacing chopped alfalfa hay with alfalfa silage in barley grain and alfalfa-based total mixed rations for lactating dairy cows

The effects of replacing chopped alfalfa hay with alfalfa silage in a fine barley grain and alfalfa-based total mixed ration (TMR) were evaluated. Diets contained (dry matter basis) 53.0% commercial energy supplement, 10.3% commercial protein supplement, and 9.7% corn silage. Diets varied in inclusion of chopped alfalfa hay and alfalfa silage, and contained either 20.0% chopped alfalfa hay and 7.0% alfalfa silage, 10.0% chopped alfalfa hay and 17.0% alfalfa silage, or 27.0% alfalfa silage. Contents of crude protein, neutral detergent fiber (NDF), acid detergent fiber, and minerals did not differ among diets. Replacing chopped alfalfa hay with alfalfa silage decreased dietary dry matter, and increased dietary soluble protein and physical effective NDF calculated as the proportion of dietary NDF retained by the 8- and 19-mm screens of the Penn State Particle Separator (peNDF(NDF)) from 13.3 to 15.6% DM. Replacing chopped alfalfa hay with alfalfa silage did not affect dry matter intake, rumen pH, rumen volatile fatty acids, blood lactate, milk fat, and milk protein percentage, but did decrease blood glucose, tended to increase blood urea, and numerically decreased milk yield and milk protein yield. A wider range in peNDF(NDF) and a higher inclusion of corn silage might have resulted in greater differences in rumen fermentation and milk production among diets. The pH of rumen fluid samples collected 4 h after feeding varied from 5.90 to 5.98, and milk fat percentage varied from 2.50 to 2.60% among diets. These values suggest that mild subacute ruminal acidosis was induced by all diets.     

Lactation performance and digestibility of forages and diets in dairy cows fed a hemicellulose extract

Inclusion of hemicellulose extract (HE) in cattle diets have shown potential for improving fiber digestibility and production efficiency. The objective of this research was to evaluate production and digestibility effects of a HE on midlactation cows. Twelve multiparous Holstein cows (142 ± 44 d in milk, 685 ± 19 kg of body weight) including 4 with ruminal fistula were used in a 2 × 2 Latin square design with 21-d periods. Cows were fed a control (CON) diet containing 55% forage [dry matter (DM) basis, 2/3 corn silage and 1/3 alfalfa hay] or a similar diet where 1.0% of the diet DM was replaced with HE (TRT). Dry matter intake averaged 27.1 and 26.9 kg/d, for CON and TRT respectively, and was not affected by addition of extract. The percentage of milk protein (3.40 vs. 3.29%) was greater, whereas the percentage of milk fat (3.91 vs. 3.80%) tended to be greater, for cows fed the CON compared with the TRT diet. Because of numerically greater milk production (38.8 vs. 39.2 kg/d) for cows fed the TRT diet, no differences were observed in component yields other than lactose (1.86 vs. 1.94 kg/d), which tended to be greater for cows fed the TRT ration. Treatment improved neutral detergent fiber (NDF) digestibility (38.6 vs. 48.1%) for the TRT diet compared with the CON diet but did not affect apparent total-tract DM (67.8 vs. 68.5%), crude protein (67.2 vs. 67.9%), acid detergent fiber (ADF; 37.1 vs. 43.3%), or starch (92.8 vs. 92.2%) digestibility. For in situ determinations, Dacron bags containing corn silage, alfalfa hay, and either the CON or TRT ration were incubated in triplicate in the rumens of the cannulated cows at 0, 3, 6, 9, 12, 24, and 48 h on d 18 of each period. Each total mixed ration was incubated only in cows assigned to the corresponding diet. For corn silage, the rate of disappearance of NDF (1.70 vs. 4.27%) and ADF (1.79 vs. 4.66%) increased for cows fed the TRT diet. For alfalfa hay, the disappearance of fraction A of DM, NDF, and ADF decreased and fraction B of DM and NDF increased with treatment. The rate of disappearance for DM (8.03 vs. 11.04%), NDF (6.30 vs. 10.28%), and ADF (5.52 vs. 9.19%) increased for the alfalfa hay in rumens of treated cows. For the total mixed ration, the disappearance of the A fraction of NDF and ADF increased for cows fed the TRT diet. Supplementing diets of lactating dairy cows with an HE has beneficial effects on fiber degradation characteristics and provides opportunities for improving animal performance.     

Effect of alfalfa forage preservation method and particle length on performance of dairy cows fed corn silage-based diets and tallow

A study was conducted to evaluate the effect of including alfalfa preserved either as silage or long-stem or chopped hay on DMI and milk fat production of dairy cows fed corn silage-based diets with supplemental tallow (T). Fifteen Holstein cows that averaged 117 DIM were used in a replicated 5 x 5 Latin square design with 21-d periods. Treatments (DM basis) were: 1) 50% corn silage:50% concentrate without T (CS); 2) 50% corn silage:50% concentrate with 2% T (CST); 3) 25% corn silage:25% short-cut alfalfa hay:50% concentrate with 2% T (SAHT); 4) 25% corn silage:25% long-cut alfalfa hay:50% concentrate with 2% T (LAHT); and 5) 25% corn silage:25% alfalfa silage:50% concentrate with 2% T (AST). Cows were allowed ad libitum consumption of a TMR fed 4 times daily. Diets averaged 16.4% CP and 30.3% NDF. Including 2% T in diets with corn silage as the sole forage source decreased DMI and milk fat percentage and yield. Replacing part of corn silage with alfalfa in diets with 2% T increased milk fat percentage and yield. The milk fat of cows fed CST was higher in trans-10 C18:1 than that of cows fed diets with alfalfa. No effect of alfalfa preservation method or hay particle length was observed on DMI and milk production. The milk fat percentage and yield were lower, and the proportion of trans-10 C18:1 in milk fat was higher for cows fed LAHT than for cows fed SAHT. Alfalfa preservation method had no effect on milk fat yield. Ruminal pH was higher for cows fed alfalfa in the diets, and it was higher for cows fed LAHT than SAHT. Feeding alfalfa silage or chopped hay appears to be more beneficial than long hay in sustaining milk fat production when 2% T is fed with diets high in corn silage. These results support the role of trans fatty acids in milk fat depression.     

Effect of replacing alfalfa silage with high moisture corn on nutrient utilization and milk production

Twenty-four multiparous lactating Holstein cows were blocked by days in milk and assigned to treatment sequences in a replicated 4x4 Latin square with 21-d periods. The four diets, formulated from alfalfa silage plus a concentrate mix based on ground high moisture ear corn, contained [dry matter (DM) basis]: 1) 20% concentrate, 80% alfalfa silage (24% nonfiber carbohydrates; NFC), 2) 35% concentrate, 65% alfalfa silage (30% NFC), 3) 50% concentrate, 50% alfalfa silage (37% NFC), or 4) 65% concentrate, 35% alfalfa silage (43% NFC). Soybean meal and urea were added to make diets isonitrogenous with equal nonprotein N (43% of total N). Intake of DM and milk yield indicated that adaptation was complete within 7 d of changing the diets within the Latin square. There were linear increases in apparent digestibility of DM and organic matter, and a linear decrease in neutral detergent fiber (NDF) digestibility with increasing dietary NFC. Solutions of significant quadratic equations yielded estimated maxima for intake of DM, organic matter, digestible organic matter, and NDF at, respectively, 37, 38, 43, and 27% dietary NFC. There were linear increases in yields of milk, protein, lactose, and solids not fat with increasing dietary NFC. Feed efficiency (milk/DM intake) yielded a quadratic response with a minimum at 27% dietary NFC. Maxima for milk fat content, fat yield, and fat-corrected milk yield were estimated to occur at, respectively, 30, 34 and 38% dietary NFC. In this short-term trial, maximal DM intake and fat-corrected milk yield indicated that the optimum concentrate for cows fed high moisture ear corn plus alfalfa silage as the only forage was equivalent to 37 to 38% dietary NFC; however, yields of milk, protein and solids not fat were still increasing at 65% dietary concentrate (43% NFC).     

Effect of applying bacterial inoculants containing different types of bacteria to corn silage on the performance of dairy cattle

This study examined the effect of applying different bacterial inoculants to corn silage at the time of ensiling on the performance of lactating dairy cows. Corn plants were harvested at 35% dry matter (DM), chopped, and ensiled in 2.4-m-wide bags after application of (1) no inoculant (CON); (2) Biotal Plus II (B2) containing Pediococcus pentosaceus and Propionibacteria freudenreichii; (3) Buchneri 40788 (BUC) containing Lactobacillus buchneri; or (4) Buchneri 500 (B500) containing Pediococcus pentosaceus and L. buchneri. All inoculants were supplied by Lallemand Animal Nutrition (Milwaukee, WI). Each of the 4 silages was included in separate total mixed rations consisting of 44% corn silage, 50% concentrate, and 6% alfalfa hay (DM basis). Fifty-two lactating Holstein cows were stratified according to milk production and parity and randomly assigned at 22 d in milk to the 4 dietary treatments. Cows were fed for ad libitum consumption and milked twice daily for 49 d. Dietary treatment did not affect intakes (kg/d) of DM (20.0), crude protein (CP; 3.7), neutral detergent fiber (NDF; 5.7), or acid detergent fiber (ADF; 3.6), or digestibility (%) of DM (73.9) or CP (72.4). However, NDF digestibility was lower in cows fed B2 compared with those fed other diets (45.3 vs. 53.0%). Consequently, cows fed B2 had lower digestible NDF intake (kg/d) than those fed other diets (2.5 vs. 3.0 kg/d). Dietary treatment did not affect milk yield (32.3 kg/d), efficiency of milk production (1.61), concentrations of milk fat (3.18%) and protein (2.79%), or yields of milk fat (1.03 kg/d) and protein (1.26 kg/d). Inoculant application to corn silage did not affect milk yield or feed intake of cows.     

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.     

Response of lactating dairy cows to diets containing wet corn gluten feed or a raw soybean hull-corn steep liquor pellet

We evaluated effects of wet corn gluten feed (WCGF) and a novel product (SHSL) containing raw soybean hulls and corn steep liquor on performance and digestion in lactating dairy cows. In Experiment 1, 46 multiparous Holstein cows were assigned to control (C), WCGF (20% of diet DM), or SHSL (20% of diet DM). Diets were fed as a total mixed ration beginning after calving. The C diet contained (dry matter [DM] basis) 30% alfalfa hay, 15% corn silage, 32% corn, 9.3% whole cottonseed, 4.4% solvent soybean meal (SBM), and 3.3% expeller SBM. The WCGF replaced 10% alfalfa hay, 5% corn silage, and 5% corn grain, while expeller SBM replaced solvent SBM to maintain diet rumen undegradable protein. The SHSL replaced 10% alfalfa hay, 5% corn silage, 3% solvent SBM, and 2% corn. Dietary crude protein averaged 18.4%. Milk, energy-corrected milk (ECM), DM intake (DMI), and ECM/DMI were similar among diets during the first 13 wk of lactation. During wk 14 through 30 postpartum, WCGF and SHSL improved milk, ECM, milk component yield, and ECM/DMI. In Experiment 2, 6 cows were used to evaluate digestibility and rumen traits. Dry matter intake and total tract digestibilities of DM, fiber, and crude protein were not different among diets. Diets did not affect ruminal liquid dilution rate, pH, or concentrations of total volatile fatty acids or ammonia, but acetate:propionate was higher for C (3.38) than for WCGF (2.79) or SHSL (2.89). The WCGF and SHSL products can serve as alternative feedstuffs in diets fed to lactating dairy cattle.     

The influence of fat and hemicellulose on methane production and energy utilization in lactating Jersey cattle

Feeding fat to lactating dairy cows may reduce methane production. Relative to cellulose, fermentation of hemicellulose is believed to result in less methane; however, these factors have not been studied simultaneously. Eight multiparous, lactating Jersey cows averaging (±SD) 98 ± 30.8 d in milk and body weight of 439.3 ± 56.7 kg were used in a twice-replicated 4 × 4 Latin square to determine the effects of fat and hemicellulose on energy utilization and methane production using a headbox-type indirect calorimetry method. To manipulate the concentration of fat, porcine tallow was included at either 0 or 2% of the diet dry matter. The concentration of hemicellulose was adjusted by manipulating the inclusion rate of corn silage, alfalfa hay, and soybean hulls resulting in either 11.3 or 12.7% hemicellulose (dry matter basis). The resulting factorial arrangement of treatments were low fat low hemicellulose (LFLH), low fat high hemicellulose (LFHH), high fat low hemicellulose (HFLH), and high fat high hemicellulose (HFHH). Neither fat nor hemicellulose affected dry matter intake, averaging 16.2 ± 1.18 kg/d across treatments. Likewise, treatments did not affect milk production, averaging 23.0 ± 1.72 kg/d, or energy-corrected milk, averaging 30.1 ± 2.41 kg/d. The inclusion of fat tended to reduce methane produced per kilogram of dry matter intake from 24.9 to 23.1 ± 1.59 L/kg, whereas hemicellulose had no effect. Increasing hemicellulose increased neutral detergent fiber (NDF) digestibility from 43.0 to 51.1 ± 2.35%. Similarly, increasing hemicellulose concentration increased total intake of digestible NDF from 6.62 to 8.42 ± 0.89 kg/d, whereas fat had no effect. Methane per unit of digested NDF tended to decrease from 64.8 to 49.2 ± 9.60 L/kg with increasing hemicellulose, whereas fat had no effect. An interaction between hemicellulose and fat content on net energy balance (milk plus tissue energy) was observed. Specifically, increasing hemicellulose in low-fat diets tended to increase net energy balance, but this was not observed in high-fat diets. These results confirm that methane production may be reduced with the inclusion of fat, whereas energy utilization of lactating dairy cows is improved by increasing hemicellulose in low-fat diets.     

Influence of fiber degradability of corn silage in diets with lower and higher fiber content on lactational performance,nutrient digestibility,and ruminal characteristics in lactating Holstein cows

The effect of neutral detergent fiber (NDF) degradability of corn silage in diets containing lower and higher NDF concentrations on lactational performance, nutrient digestibility, and ruminal characteristics in lactating Holstein cows was measured. Eight ruminally cannulated Holstein cows averaging 91 ± 4 (standard error) days in milk were used in a replicated 4 × 4 Latin square design with 21-d periods (7-d collection periods). Dietary treatments were formulated to contain either conventional (CON; 48.6% 24-h NDF degradability; NDFD) or brown midrib-3 (BM3; 61.1% 24-h NDFD) corn silage and either lower NDF (LNDF) or higher NDF (HNDF) concentration (32.0 and 35.8% of ration dry matter, DM) by adjusting the dietary forage content (52 and 67% forage, DM basis). The dietary treatments were (1) CON-LNDF, (2) CON-HNDF, (3) BM3-LNDF, and (4) BM3-HNDF. Data were analyzed as a factorial arrangement of diets within a replicated Latin square design with the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) with fixed effects of NDFD, NDF, NDFD × NDF, period(square), and square. Cow within square was the random effect. Time and its interactions with NDFD and NDF were included in the model when appropriate. An interaction between NDFD and NDF content resulted in the HNDF diet decreasing dry matter intake (DMI) with CON corn silage but not with BM3 silage. Cows fed the BM3 corn silage had higher DMI than cows fed the CON corn silage, whereas cows fed the HNDF diet consumed less DM than cows fed the LNDF diet. Cows fed the BM3 diets had greater energy-corrected milk yield, higher milk true protein content, and lower milk urea nitrogen concentration than cows fed CON diets. Additionally, cows fed the BM3 diets had greater total-tract digestibility of organic matter and NDF than cows fed the CON diets. Compared with CON diets, the BMR diets accelerated ruminal NDF turnover. When incorporated into higher NDF diets, corn silage with greater in vitro 24-h NDFD and lower undegradable NDF at 240 h of in vitro fermentation (uNDF240) allowed for greater DMI intake than CON. In contrast, for lower NDF diets, NDFD of corn silage did not affect DMI, which suggests that a threshold level of inclusion of higher NDFD corn silage is necessary to observe enhanced lactational performance. Results suggest that there is a maximum gut fill of dietary uNDF240 and that higher NDFD corn silage can be fed at greater dietary concentrations.     

Effect of supplemental tallow on performance of dairy cows fed diets with different corn silage:alfalfa silage ratios

A study was conducted to investigate the response to supplemental tallow of lactating cows fed basal diets with different alfalfa silage:corn silage ratios. We postulated that supplemental tallow will have decreasing negative effects on rumen fermentation, dry matter intake (DMI), and milk fat percentage as the dietary ratio of alfalfa silage:corn silage is increased. Eighteen Holstein cows averaging 134 +/- 14 d in milk were used in a replicated 6 x 6 Latin square design with 21-d periods. Treatments were arranged as a 2 x 3 factorial with 0 or 2% tallow (DM basis) and three forage treatments: 1) 50% of diet DM as corn silage, 2) 37.5% corn silage and 12.5% alfalfa silage, and 3) 25% corn silage and 25% alfalfa silage. Cows were allowed ad libitum consumption of a total mixed ration. Diets were formulated to contain 18% crude protein and 32% neutral detergent fiber. No fat x forage treatment interactions were observed. Fat supplemented cows had lower DMI and produced more milk with less milk fat content relative to non-supplemented cows. Concentration of trans-octadecenoic acids was higher in milk fat of tallow-supplemented cows. Tallow supplementation had no effect on ruminal pH and acetate:propionate ratio, but tended to decrease total volatile fatty acid (VFA) concentration in the rumen. Increasing the proportion of alfalfa silage increased DMI, milk fat percentage, and milk fat yield regardless of the fat content of the diet. Total VFA concentration and acetate:propionate ratio in the rumen were increased in response to higher levels of alfalfa in the diets. These results suggest that replacing corn silage with alfalfa silage did not alleviate the negative response of dairy cows to tallow supplementation at 2% of diet DM.     

A pelleted combination of raw soyhulls and condensed corn steep liquor for lactating dairy cows

An experiment was conducted to evaluate the effect of a pelleted combination of raw soyhulls and condensed corn steep liquor on performance and plasma metabolites when fed to replace a portion of the grain and forage in diets for lactating dairy cows. The raw soybean hull-corn steep liquor pellet (SHSL) contained 24.2% crude protein, 8.7% rumen undegradable protein, 28.9% acid detergent fiber, 36.7% neutral detergent fiber, and 2.5% ether extract (% of dry matter, [DM]). Eighteen multiparous Holstein cows were assigned to one of three diets in a replicated 3 x 3 Latin square design with 28-d periods. Cows were blocked by pretreatment body weight and energy-corrected milk (ECM) and assigned to control, SHSL (20.7% of diet DM), or pelleted raw soybean hulls ([PSH] 14.3% of diet DM). The SHSL product replaced 6.2% alfalfa hay, 3.7% corn silage, 6.6% corn, and 3.3% soybean meal (SBM), and 1.7% expeller SBM replaced solvent SBM in order to maintain dietary levels of rumen undegradable protein. PSH replaced 6.2% alfalfa hay, 3.7% corn silage, and 5.1% corn. Diet crude protein (%) and energy density (Mcal/kg NEL) were 16.6 and 1.64, 16.3 and 1.65, 17.1 and 1.63 for control, SHSL, and PSH, respectively. Cows fed PSH consumed more DM than cows fed control, with the intake of cows fed SHSL being intermediate. SHSL and PSH increased ECM, milk protein, and solids-notfat and showed higher concentrations of milk and plasma urea N and total alpha-amino N in plasma than the control diet. Furthermore, feeding SHSL tended to improve the ratio of ECM to DM intake. There was no effect of diet on concentrations of total essential and nonessential amino acids in plasma. These production data suggest SHSL can replace a portion of the forage, grain, and SBM in diets for lactating dairy cows without decreasing lactational performance.     

Effect of replacing corn silage with annual ryegrass silage on nutrient digestibility,intake, and milk yield for lactating dairy cows

Twenty Holstein cows were used in an 8-wk randomized block design study to determine the effects of replacing corn silage with ryegrass silage on nutrient intake, apparent digestion, milk yield, and milk composition. The 8-wk trial consisted of a 2-wk preliminary period followed by a 6-wk collection period. Experimental diets were formulated to provide 55.5% of the total dry matter (DM) as forage. Ryegrass silage was substituted for 0, 35, 65, and 100% of DM provided by corn silage. Dietary concentrations of neutral detergent fiber (NDF) and acid detergent fiber (ADF) increased as ryegrass silage replaced corn silage. Intake of DM and crude protein (CP) was similar for all treatments, but intake of NDF and ADF increased linearly as ryegrass silage replaced corn silage. Apparent digestibility of DM declined linearly, whereas digestibility of CP increased linearly as ryegrass silage replaced corn silage. Apparent digestibility of NDF and ADF was highest for the diets in which ryegrass or corn silages provided all of the forage, resulting in a quadratic response. Dry matter intake was not different among treatments. Yield of milk, fat, and protein increased as ryegrass silage replaced corn silage. No differences were observed for body weight change, body condition score, and serum urea nitrogen concentration, but serum glucose concentration increased with increasing dietary proportion of ryegrass silage. These results indicate that substituting ryegrass silage for a portion or all of the corn silage in diets fed to lactating dairy cows can improve yield of milk and components.     

Short communication: Production performance and nutrient digestibility of lactating dairy cows fed diets with and without addition of a live-yeast supplement

The objective of this study was to evaluate the use of a live-yeast product when feeding relatively high-forage diets to high-producing cows in mid lactation. Eight primiparous [607 ± 43 kg of body weight (BW) and 130 ± 16 d in milk (DIM) at the beginning of the experiment] and 16 multiparous (706 ± 63 kg of BW and 137 ± 22 DIM at the beginning of the experiment) Holstein cows were blocked by parity and DIM, and randomly assigned to 1 of 2 diets (control vs. yeast) for a 12-wk period according to a randomized complete block design. The formulated diets contained 50.4% corn silage, 10.4% alfalfa hay, and 39.2% concentrate. The yeast diet was formulated to provide approximately 5.4 × 10¹¹ cfu/d of Saccharomyces cerevisiae (BeneSacc; Global Nutritech Biotechnology LLC, Richmond, VA). Total-tract nutrient digestibility was estimated using 240-h undigested neutral detergent fiber (NDF) as an internal marker. Supplementing live yeast to lactating dairy cows did not affect dry matter intake (25.0 kg/d), milk yield (38.6 kg/d), milk fat concentration (4.78%), milk fat yield (1.83 kg/d), milk protein concentration (3.09%), milk protein yield (1.18 kg/d), milk lactose concentration (4.79%), milk lactose yield (1.84 kg/d), BW gain (?0.05 kg/d), or body condition score gain (0.16 units). The digestibility of dry matter was greater for the control treatment than for the yeast treatment (69.3 and 67.1%, respectively), but the digestibilities of crude protein (61.5%), NDF (40.5%), and starch (98.6%) were not affected by treatment. In conclusion, supplementation of live yeast did not affect production performance or nutrient digestibility of high-producing cows in mid lactation. The reasons for the lack of effect are not clear, but an evaluation of interactions between yeast and rumen buffer supplementation is warranted.     

Corn Silage Partially Replacing Short Alfalfa Hay to Optimize Forage Use in Total Mixed Rations for Lactating Cows

We theorized that adding corn silage to a total mixed ration with alfalfa hay as the sole dietary forage would improve nutrient intake and chewing activity and thereby improve rumen fermentation and milk production. The objective of this research was to determine the effects of partial replacement of short alfalfa [physically effective (pe) neutral detergent fiber (NDF) >1.18 mm (peNDF_>1.18) = 33.2%] with corn silage (CS, peNDF_>1.18 = 51.9%) in yellow grease-supplemented total mixed rations on feed intake, chewing behavior, rumen fermentation, and lactation performance by dairy cows. Four multiparous (138 ± 3 d in milk) and 4 primiparous (115 ± 10 d in milk) Holstein cows were used in a 4 × 4 Latin square design experiment with four 21-d periods. Each period had 14 d of adaptation and 7 d of sampling, and parity was the square. Treatments were diets [dry matter (DM) basis] with 1) 40% alfalfa hay (ALF), 2) 24% alfalfa hay + 16% CS (CS40), 3) 20% alfalfa hay + 20% CS (CS50), and 4) 16% alfalfa hay + 24% CS (CS60). Diets had a forage-to-concentrate ratio of 40:60 on a DM basis. Cows had greater intake of DM and thus greater intakes of net energy for lactation, NDF, and peNDF when CS partially replaced alfalfa hay. Replacing alfalfa hay with CS increased daily eating and chewing times in all cows, and increased rumen pH at 4 h postfeeding in multiparous cows. Apparent total-tract digestibility coefficients for crude protein (CP) and NDF were not different among cows fed ALF, CS40, and CS50, but were lower for CS60 than for ALF. Energy-corrected milk yield was greater for CS40 and CS60 than for ALF. Milk protein yield was increased when CS replaced 40, 50, and 60% of alfalfa hay. Milk lactose was greater only for CS60, but milk lactose yield was greater for CS50 and CS60 than for ALF. Milk percentage and yield of fat did not differ among treatments. Therefore, CS partially replacing short alfalfa hay increased DM intake, consequently increased net energy for lactation and physically effective fiber intakes, and thus, improved milk and milk protein and lactose yields.     

Performance of dairy cows fed diets with similar proportions of undigested neutral detergent fiber with wheat straw substituted for alfalfa hay,corn silage,or both

This study evaluated the effects of feeding diets that were formulated to contain similar proportions of undigested neutral detergent fiber (uNDF) from forage, with wheat straw (WS) substituted for corn silage (CS), alfalfa hay (AH), or both. The diets were fed to lactating dairy cows and intake, digestibility, blood metabolites, and milk production were examined. Thirty-two multiparous Holstein cows (body weight = 642 ± 50 kg; days in milk = 78 ± 11 d; milk production = 56 ± 6 kg/d; mean ± standard deviation) were used in a randomized block design with 6-wk periods after a 10-d covariate period. Each period consisted of 14 d of adaptation followed by 28 d of data collection. The control diet contained CS and AH as forage sources (CSAH) with 17% of dietary dry matter as uNDF after 30 h of incubation (uNDF₃₀). Wheat straw was substituted for AH (WSCS), CS (WSAH), or both (WSCSAH) on an uNDF₃₀ basis, and beet pulp was used to obtain similar concentrations of NDF digestibility after 30 h of incubation (NDFD₃₀ = 44.5% of NDF) across all diets. The 4 diets also contained similar concentrations of net energy for lactation and metabolizable protein. Dry matter intake was greatest for WSCS (27.8 kg/d), followed by CSAH (25.7 kg/d), WSCSAH (25.2 kg/d), and WSAH (24.2 kg/d). However, yields of milk, 3.5% fat-corrected milk (FCM), and energy-corrected milk did not differ, resulting in higher FCM efficiency (kg of FCM yield/kg of dry matter intake) for WSAH (1.83) and WSCSAH (1.79), followed by CSAH (1.69) and WSCS (1.64). Milk protein percentage was greater for CSAH (2.84%) and WSCS (2.83%) than for WSAH (2.78%), and WSCSAH (2.81%) was intermediate. The opposite trend was observed for milk urea nitrogen, which was lower for CSAH (15.8 mg/dL), WSCS (15.8 mg/dL), and WSCSAH (17.0 mg/dL) than for WSAH (20 mg/dL). Total-tract NDF digestibility and ruminal pH were greater for diets containing WS than the diet without WS (CSAH), but digestibility of other nutrients was not affected by dietary treatments. Cows fed WSAH had less body reserves (body weight change = −13.5 kg/period) than the cows fed the other diets, whereas energy balance was greatest for those fed WSCS. The results showed that feeding high-producing dairy cows diets containing different forage sources but formulated to supply similar concentrations of uNDF₃₀ while maintaining NDFD_30, net energy for lactation, and metabolizable protein constant did not influence milk production. However, a combination of WS and CS (WSCS diet) compared with a diet with CS and AH improved feed intake, ruminal pH, total-tract NDF digestibility, and energy balance of dairy cows.     

Ryegrass or alfalfa silage as the dietary forage for lactating dairy cows

Renewed interest exists in using grass forages to dilute the higher crude protein (CP) and lower digestible fiber present in legumes fed to lactating dairy cows. A 3 x 3 Latin square feeding study with 4-wk periods was conducted with 24 Holstein cows to compare ryegrass silage, either untreated control or macerated (intensively conditioned) before ensiling, with alfalfa silage as the sole dietary forage. Ryegrass silages averaged [dry matter (DM) basis] 18.4% CP, 50% neutral detergent fiber (NDF), and 10% indigestible acid detergent fiber (ADF) (control) and 16.6% CP, 51% NDF, and 12% indigestible ADF (macerated). Alfalfa silage was higher in CP (21.6%) and lower in NDF (44%) but higher in indigestible ADF (26%). A lower proportion of the total N in macerated ryegrass silage was present as nonprotein N than in control ryegrass and alfalfa silages. Diets were formulated to contain 41% DM from either rye-grass silage, or 51% DM from alfalfa silage, plus high moisture corn, and protein concentrates. Diets averaged 17.5% CP and 28 to 29% NDF. The shortfall in CP on ryegrass was made up by feeding 7.6% more soybean meal. Intake and milk yields were similar on control and macerated ryegrass; however, DM intake was 8.3 kg/d greater on the alfalfa diet. Moreover, feeding the alfalfa diet increased BW gain (0.48 kg/d) and yield of milk (6.1 kg/d), FCM (6.8 kg/d), fat (0.26 kg/d), protein (0.25 kg/d), lactose (0.35 kg/d), and SNF (0.65 kg/d) versus the mean of the two ryegrass diets. Both DM efficiency (milk/DM intake) and N efficiency (milk-N/N-intake) were 27% greater, and apparent digestibility was 16% greater for DM and 53% greater for NDF and ADF, on the ryegrass diets. However, apparent digestibility of digestible ADF was greater on alfalfa (96%) than on ryegrass (average = 91%). Also, dietary energy content (estimated as net energy of lactation required for maintenance, milk yield, and weight gain) per unit of digested DM was similar for all three diets. Results of this trial indicated that, relative to ryegrass silage, feeding alfalfa silage stimulated much greater feed intake, which supported greater milk production.     

Interaction of molasses and monensin in alfalfa hay- or corn silage-based diets on rumen fermentation, total tract digestibility, and milk production by Holstein cows

Sugar supplementation can stimulate rumen microbial growth and possibly fiber digestibility; however, excess ruminal carbohydrate availability relative to rumen-degradable protein (RDP) can promote energy spilling by microbes, decrease rumen pH, or depress fiber digestibility. Both RDP supply and rumen pH might be altered by forage source and monensin. Therefore, the objective of this study was to evaluate interactions of a sugar source (molasses) with monensin and 2 forage sources on rumen fermentation, total tract digestibility, and production and fatty acid composition of milk. Seven ruminally cannulated lactating Holstein cows were used in a 5 × 7 incomplete Latin square design with five 28-d periods. Four corn silage diets consisted of 1) control (C), 2) 2.6% molasses (M), 3) 2.6% molasses plus 0.45% urea (MU), or 4) 2.6% molasses plus 0.45% urea plus monensin sodium (Rumensin, at the intermediate dosage from the label, 16 g/909 kg of dry matter; MUR). Three chopped alfalfa hay diets consisted of 1) control (C), 2) 2.6% molasses (M), or 3) 2.6% molasses plus Rumensin (MR). Urea was added to corn silage diets to provide RDP comparable to alfalfa hay diets with no urea. Corn silage C and M diets were balanced to have 16.2% crude protein; and the remaining diets, 17.2% crude protein. Dry matter intake was not affected by treatment, but there was a trend for lower milk production in alfalfa hay diets compared with corn silage diets. Despite increased total volatile fatty acid and acetate concentrations in the rumen, total tract organic matter digestibility was lower for alfalfa hay-fed cows. Rumensin did not affect volatile fatty acid concentrations but decreased milk fat from 3.22 to 2.72% in corn silage diets but less in alfalfa hay diets. Medium-chain milk fatty acids (% of total fat) were lower for alfalfa hay compared with corn silage diets, and short-chain milk fatty acids tended to decrease when Rumensin was added. In whole rumen contents, concentrations of trans-10, cis-12 C_18:2 were increased when cows were fed corn silage diets. Rumensin had no effect on conjugated linoleic acid isomers in either milk or rumen contents but tended to increase the concentration of trans-10 C_18:1 in rumen samples. Molasses with urea increased ruminal NH₃-N and milk urea N when cows were fed corn silage diets (6.8 vs. 11.3 and 7.6 vs. 12.0 mg/dL for M vs. MU, respectively). Based on ruminal fermentation characteristics and fatty acid isomers in milk, molasses did not appear to promote ruminal acidosis or milk fat depression. However, combinations of Rumensin with corn silage-based diets already containing molasses and with a relatively high nonfiber carbohydrate:forage neutral detergent fiber ratio influenced biohydrogenation characteristics that are indicators of increased risk for milk fat depression.