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.     

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.     

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.     

Influence of rumen undegradable protein levels on feed intake and milk production of dairy cows

Twenty-seven dairy cows in midlactation were utilized in two experiments using 15 and 12 cows to determine effects of varying the delivery of ruminally undegraded protein on feed intake, milk production, and some rumen and plasma characteristics. In Experiment 1, cows consumed alfalfa silage ad libitum and one of three barley-based concentrates with either soybean meal (a rapidly rumen degraded protein source), corn gluten meal (a slowly degraded protein source), or an equal mixture of the two, fed at the rate of .36 kg/kg of milk produced. In Experiment 2, cows were fed total mixed diets based upon alfalfa silage, barley, and either soybean meal, corn gluten meal, or a mixture of soybean meal and whey powder (a protein source very rapidly degraded in the rumen). In sacco incubation procedures were used to estimate degradability of protein in all diets. All diets exceeded Agricultural Research Council recommendations for rumen degraded and undegraded protein as well as NRC recommendations for degraded protein. However, one to three of the six total diets, depending upon assumed ruminal turnover rates, did not meet NRC recommendations for undegraded protein. Production parameters, include DMI as well as milk yield and composition, were not influenced by diet in either experiment. Results do not support NRC recommendations for ruminally undegraded protein for midlactation dairy cows producing about 30 kg/d of milk and broadly support the lower recommendations of the Agricultural Research Council. Results also appear to question use of dietary energy intake to predict net rumen microbial protein yield.     

Effect of formic acid or formaldehyde treatment of alfalfa silage on nutrient utilization by dairy cows.

Third-cutting alfalfa with 37% DM was ensiled untreated or treated with either 2.8 g of formic acid/100 g of DM or .31 g of formaldehyde/100 g of DM and fed to lactating dairy cows in two experiments. Silage treated with formic acid had the lowest pH and concentrations of NPN, NH3, and total free AA. Both treatments decreased rumen in vitro protein degradability but did not affect in vitro rumen plus pepsin digestibility. In trial 1, part 1, 22 Holstein cows received a standard diet for 18 d postpartum and then were fed for 6 wk one of three diets containing 98% alfalfa silage DM. Although DMI was comparable, yields of milk, SCM, fat, protein, lactose, and SNF were higher when treated silages were fed. Plasma concentrations of branched-chain, essential, and total AA increased when formic acid-treated silage was fed. Rumen pH and concentrations of NH3 and VFA were similar for all diets. Rumen escape protein, estimated using 15N as a microbial protein marker, was increased more by formic acid than by formaldehyde treatment. In trial 1, part 2, supplementation with 4.8% fish meal increased concentration of milk protein and yields of milk, protein, lactose, and SNF. Milk urea concentration was higher on the untreated silage diet. Total tract apparent DM and N digestibilities were not affected by silage treatment, although fish meal decreased apparent DM digestibility. In trial 2, 80:20 alfalfa silage:ground corn diets were fed to 12 midlactation cows in a 3 x 3 Latin square study. Milk production was unaffected, but milk protein concentration and DMI were higher when treated silages were fed. Feeding treated silages increased plasma concentrations of branched-chain AA, essential AA, and total AA. Formaldehyde and especially formic acid treatment effectively improved utilization of nutrients in alfalfa silage by lactating dairy cows.     

Effect of type and level of dietary fat on rumen fermentation and performance of dairy cows fed corn silage-based diets

The objective of this study was to investigate the effects of tallow and choice white grease (CWG) fed at 0, 2, and 4% of the diet dry matter (DM) on rumen fermentation and performance of dairy cows when corn silage is the sole forage source. Fifteen midlactation Holstein cows were used in a replicated 5 x 5 Latin square design with 21-d periods. Treatments were 0% fat (control), 2% tallow, 2% CWG, 4% tallow, and 4% CWG (DM basis). The forage:concentrate ratio was 50:50, and diets were formulated to contain 18% crude protein and 32% neutral detergent fiber (DM basis). Cows were allowed ad libitum consumption of diets fed twice daily as total mixed rations. Cows fed supplemental fat had lower DM intake and produced less milk and milk fat than cows fed the control diet. Feeding 4% fat reduced milk production and milk fat yield relative to feeding 2% fat. Treatments had little effect on the concentration of trans-octadecenoic acids in milk fat. Total trans fatty acids were poorly related to changes in milk fat percentage. Ruminal pH and total volatile fatty acids concentration were not affected by supplemental fat. The acetate:propionate ratio, NH3-N, and numbers of protozoa in the rumen were significantly decreased when fat was added to the diets. Source of dietary fat did not affect rumen parameters. There was no treatment effect on in situ corn silage DM and neutral detergent fiber disappearance. Including fat in corn silage-based diets had negative effects on milk production and rumen fermentation regardless of the source or level of supplemental fat.     

Effects of particle size of alfalfa-based dairy cow diets on chewing activity,ruminal fermentation,and milk production

Effects offorage particle size measured as physically effective NDF and ratio of alfalfa silage to alfalfa hay of diets on feed intake, chewing activity, particle size reduction, salivary secretion, ruminal fermentation, and milk production of dairy cows were evaluated using a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. The diets consisted of 60% barley-based concentrate and 40% forage, comprised either of 50:50 or 25:75 of alfalfa silage:alfalfa hay, and alfalfa hay was either chopped or ground. Various methods were used to determine physically effective NDF content of the diets. Cows surgically fitted with ruminal and duodenal cannulas were offered ad libitum access to these total mixed diets. The physically effective NDF content of the diets was significantly lower when measured using the Penn State Particle Separator than when measured based on particles retained on 1.18-mm screen. Intake of DM was increased by increasing the ratio of silage to hay but was not affected by physically effective NDF content of diets. Eating time (hours per day) was not affected by the physically effective NDF content of diets, although cows spent more time eating per unit of DM or NDF when consuming high versus low alfalfa hay diets. Ruminating time (hours per day) was increased with increased physically effective NDF content of the diets. Rumen pH was affected more by changing dietary particle size than altering the ratio of silage to hay. Feeding chopped hay instead of ground hay improved ruminal pH status: time during which ruminal pH was above 6.2 increased and time during which ruminal pH was below 5.8 decreased. Milk production was increased by feeding higher concentrations of alfalfa silage due to increased DM intake, but was not affected by dietary particle size. Feed particle size, expressed as mean particle length or physically effective NDF was moderately correlated with ruminating time but not with eating time. Although physically effective NDF and chewing time were not correlated to mean rumen pH, they were negatively correlated to the area between the curve and pH 5.8, indicating a positive effect on reducing the risk of acidosis. Milk fat content was correlated to rumen pH but not to physically effective NDF or chewing activity. These results indicate that increasing physically effective NDF content of the diets increased chewing activity and improved rumen pH status but had limited effect on milk production and milk fat content.     

Effects of rearing diet, age at freshening, and lactation feeding system on performance

This two-phase trial involved 83 Holstein heifers. The rearing phase consisted of two diets (alfalfa silage plus corn grain for ad libitum intake vs. corn silage plus urea for ad libitum intake) and two breeding age groups (13 vs. 16 mo). The lactation phase compared the above treatments plus two lactation feeding systems: concentrate fed individually to production versus a TMR. The heifers were assigned randomly to the rearing phase at 7 wk of age and fed their respective diets until 14 d prepartum. They were placed on preassigned lactation diets 14 d prepartum and remained on the lactation phase for 550 consecutive d. Daily gains and height at the withers were similar between forage groups during the first half of the rearing phase; in the second half, the heifers fed alfalfa silage were taller at the withers. Those fed corn silage consumed less DM and CP throughout the rearing phase and gained more BW than the heifers fed alfalfa in the latter half. There were no differences in daily gain or DMI between the breeding age groups. In the lactation phase, the group fed alfalfa for ad libitum intake consumed more DM and gave more milk during the first 90 d of lactation than heifers fed corn silage. However, after 90 d the difference in cumulative milk production was not significant. There were no differences in milk production. FCM, or DMI between breeding age groups. The cows fed concentrate consumed more DM and gave more milk during the first 90 d of lactation. By 550 d, there were no differences. Feeding high levels of corn silage can cause heifers to have lower DMI in early lactation. These differences tend to disappear during the second lactation.     

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.     

Partial replacement of corn silage with whole-plant soybean and black oat silages for dairy cows

This study aimed to evaluate the effects of partially replacing corn silage (CS) with whole-plant soybean silage (SS) or black oat silage (OS) on nutrient intake and digestibility, in vitro neutral detergent fiber degradability of silages, feeding behavior, rumen fermentation, and performance of dairy cows. Twenty-four lactating Holstein cows (6 of which were rumen-cannulated) with 32.5 ± 4.92 kg/d milk yield, 150 ± 84.8 days in milk, and 644 ± 79.0 kg of body weight were used in a 3 × 3 Latin square design to evaluate the following treatments: (1) corn silage diet (CSD): using corn silage as the only forage source in the diet [48% dietary dry matter (DM)]; (2) whole-plant soybean silage diet (SSD): SS replacing 16% of corn silage from CSD; and (3) black oat silage diet (OSD): OS replacing 16% of corn silage from CSD. The inclusion of OS and SS decreased intakes of DM, organic matter, and crude protein. Corn silage had the greatest in vivo effective degradability of DM, and SS had the least effective degradability of neutral detergent fiber. The OSD treatment decreased milk and protein yields, whereas SSD increased rumen ammonia nitrogen concentration compared with the other diets. Cows fed OSD exhibited a greater preference for feed with small particles (<4 mm) compared with those fed SSD. Cows fed treatments containing either SS or OS at the expense of CS had increased rumination and chewing activities. Although replacing CS with OS and SS reduced feed intake, SS had no effect on productive performance of 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.     

Effects of feeding alfalfa hay on chewing, rumen pH, and milk fat concentration of dairy cows fed wheat dried distillers grains with solubles as a partial substitute for barley silage

The objective of this study was to determine the effects of feeding alfalfa hay on chewing activity, rumen fermentation, and milk fat concentration of dairy cows fed wheat-based dried distillers grains with solubles (DDGS) as a partial replacement of barley silage. Thirty lactating Holstein cows (220 ± 51 DIM), 6 of which were ruminally cannulated, were used in a 3 × 3 Latin square design with 21-d periods. Cows were fed a control diet [CON; 50% barley silage and 50% concentrate mix on a dry matter (DM) basis], a diet in which barley silage was replaced with DDGS at 20% of dietary DM (DG), or a diet in which barley silage was replaced with DDGS and alfalfa hay at 20 and 10% of dietary DM, respectively (DG+AH). All diets contained approximately 20% crude protein. Compared with the CON diet, cows fed DG and DG+AH diets respectively had greater DM intake (20.1 vs. 23.1 and 22.7 kg/d); yields of milk (24.5 vs. 27.3 and 28.1 kg/d), milk protein (0.88 vs. 0.99 and 1.01 kg/d), and milk lactose (1.11 vs. 1.24 and 1.29 kg/d); and body weight gain (0.25 vs. 1.17 and 1.23 kg/d). However, compared with cows fed the CON diet, cows fed the DG and DG+AH diets respectively had lower chewing time (38.3 vs. 30.7 and 31.5 min/kg of DM intake), mean rumen pH (6.11 vs. 5.88 and 5.84), and minimum rumen pH (5.28 vs. 5.09 and 5.07) and a greater duration that rumen pH was below 5.8 (7.3 vs. 11.2 and 12.0 h/d). However, these response variables did not differ between cows fed the DG and DG+AH diets. Milk fat concentration differed among the 3 diets (3.92, 3.60, and 3.38% for CON, DG, and DG+AH, respectively), but milk fat yield was not affected by treatment. These results indicate that partially replacing barley silage with DDGS can improve productivity of lactating dairy cows but may decrease chewing time, rumen pH, and milk fat concentration, and that dietary inclusion of alfalfa hay may not alleviate such responses.     

Wet corn gluten feed as a supplement for lactating dairy cattle and growing heifers

A lactation trial and a heifer growth trial were conducted to evaluate use of wet corn gluten feed by dairy herds. Twelve multiparous and 4 primiparous Holsteins were assigned to 4 x 4 Latin squares blocked according to previous production or parity. Animals received increasing amounts of wet corn gluten feed, up to 36% of ration DM, in place of a dry corn and soybean meal concentrate mixture. Each kilogram of wet corn gluten feed DM replaced .9 kg concentrate DM. Diets were based on ensiled forage with 33% of forage DM from wilted alfalfa silage and the remainder from corn silage. Forage and supplement were fed separately. Milk production, composition, and DM intake were not affected by increased feeding of wet corn gluten feed. Higher producing cows performed well on this feed. Wet corn gluten feed was generally acceptable when fed separately, but two animals refused sizable portions when fed the highest amount. Wet corn gluten feed can be utilized in traditional stall feeding of dairy cattle, and individual feeding should allow better management of this feed resource by limiting the amount offered to cattle that find it unpalatable. Wet corn gluten feed is also an adequate supplement for raising dairy replacements, allowing more rapid utilization of this perishable feed resource by the dairy herd.     

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.     

Influence of corn silage hybrid type on lactation performance by Holstein dairy cows

The primary objective of this study was to determine lactation performance by dairy cows fed nutridense (ND), dual-purpose (DP), or brown midrib (BM) corn silage hybrids at the same concentration in the diets. A secondary objective was to determine lactation performance by dairy cows fed NutriDense corn silage at a higher concentration in the diet. One hundred twenty-eight Holstein and Holstein × Jersey cows (105 ± 38 d in milk) were stratified by breed and parity and randomly assigned to 16 pens of 8 cows each. Pens were then randomly assigned to 1 of 4 treatments. Three treatment total mixed rations (TMR; DP40, BM40, and ND40) contained 40% of dry matter (DM) from the respective corn silage hybrid and 20% of DM from alfalfa silage. The fourth treatment TMR had ND corn silage as the sole forage at 65% of DM (ND65). A 2-wk covariate adjustment period preceded the treatment period, with all pens receiving a TMR with equal proportions of DP40, BM40, and ND40. Following the covariate period, cows were fed their assigned treatment diets for 11 wk. nutridense corn silage had greater starch and lower neutral detergent fiber (NDF) content than DP or BM, resulting in ND40 having greater energy content (73.2% of total digestible nutrients, TDN) than DP40 or BM40 (71.9 and 71.4% TDN, respectively). Cows fed BM40 had greater milk yield than DP40, whereas ND40 tended to have greater milk yield and had greater protein and lactose yields compared with DP40. No differences in intake, component-corrected milk yields, or feed efficiency were detected between DP40, BM40, and ND40. Milk yield differences may be due to increased starch intake for ND40 and increased digestible NDF intake for BM40 compared with DP40. Intake and milk yield and composition were similar for ND40 compared with BM40, possibly due to counteracting effects of higher starch intake for ND40 and higher digestible NDF intake for BM40. Feeding ND65 reduced intake, and thus milk and component yields, compared with ND40 due to either increased ruminal starch digestibility or increased rumen fill for ND65. Nutridense corn silage was a viable alternative to both DP and BM at 40% of diet DM; however, lactation performance was reduced when nutridense corn silage was fed at 65% of DM.     

Effects of the chop lengths of alfalfa silage and oat silage on feed intake, milk production, feeding behavior, and rumen fermentation of dairy cows

Effects of chop length (shorter: 6 mm, or longer: 19 mm) of alfalfa silage and oat silage were determined in 16 mid-lactation Holstein cows, 4 of which were rumen cannulated, using a replicated 4 × 4 Latin square design with a 2 × 2 arrangement of treatments. Experimental periods were 21 d long and consisted of 14 d of adaptation and 7 d of sampling. Cows received a total mixed ration containing [dry matter (DM) basis] 42.0% barley grain-based energy supplement, 10% protein supplement, and 24% of DM longer chop or shorter chop alfalfa silage and 24% of DM longer chop or shorter chop oat silage. Rumen pH was measured continuously, and rumen liquid flow rates were determined in rumen-cannulated cows. Feeding behavior was determined by videotaping, and meal patterns were determined by continuously weighing the feed in the bunk of 8 cows. Reducing the chop length of alfalfa silage and oat silage reduced the average geometric particle length from 14.2 to 10.9 mm and from 13.4 to 10.4 mm, respectively. Reducing the alfalfa chop length did not affect feed intake, whereas reducing the oat silage chop length increased DM intake from to 19.4 to 21.2 kg/d. Reducing the chop lengths of alfalfa silage and oat silage chop length did not affect milk production, rumen fermentation, feeding behavior, meal patterns, and blood metabolites. Daily milk yield, milk fat percentage, and milk protein percentage averaged 36.1 kg/d, 3.00%, and 3.16%, respectively, across diets. The low milk fat percentages suggest that the diets induced subacute ruminal acidosis. This was also substantiated by the rumen pH, which was below 5.6 for more than 122 min/d for all diets. The onset of subacute ruminal acidosis despite apparently adequate dietary neutral detergent fiber content and particle size distribution as well as the long duration of chewing might be attributed to sorting against long feed particles.     

Effect of wet or dry corn gluten feed on nutrient digestibility and milk yield and composition.

A 22-wk trial was conducted to determine variations in nutrient concentrations of wet and dry corn gluten feed and their effect on nutrient digestibility and milk yield and composition. Holstein cows (n = 48) were blocked at parturition by parity and assigned randomly within block to one of three diets. All cows were fed a control TMR containing corn silage, ground corn, and commercial concentrate plus 2.3 kg/d of alfalfa hay during the 2-wk adjustment period. Thereafter, control diet was fed as wet or dry corn gluten feed substituted for 27% of dietary DM supplied by the control diet. Each cow received TMR for ad libitum consumption. Variations in nutrient concentrations of corn gluten feed were observed throughout the trial. The coefficient of variation was highest for ADIN, and standard deviation was highest for NDF. Intake of CP and NDF and apparent digestibility of DM were greatest when wet or dry corn gluten feed was fed. No differences in DMI, milk yield, and percentages of milk protein, lactose, or SNF were observed, but milk fat percentage was lowest when dry corn gluten feed was fed. Results indicate that corn gluten feed can replace 27% of dietary DM without altering milk yield, but new deliveries should be sampled regularly and amounts fed adjusted to compensate for varying nutrient concentrations.     

Impact of feeding a raw soybean hull-condensed corn steep liquor pellet on induced subacute ruminal acidosis in lactating cows

We used four ruminally cannulated, multiparous Holstein cows (690 kg; 21 kg/d milk) in a 2-period crossover design to determine the impact of feeding a raw soybean hull-corn steep liquor pellet (SHSL) on induced subacute ruminal acidosis (SARA) in lactating cows. Cows were fed control [30% alfalfa hay, 15% corn silage, 34% corn, 9% whole cottonseed, 5% soybean meal (SBM)] or SHSL (20% of diet DM) diets as TMR. SHSL replaced 6.2% alfalfa hay, 3.7% corn silage, 6.6% corn, and 3.3% SBM. Periods were 15 d (10 d adaptation, 2 d for prechallenge measures, and 3 d of SARA challenge). Cows were fed once daily at a common DMI dictated by the cow consuming the least. Cows were fasted 12 h before the first SARA challenge. For each of the three SARA challenges, cows were offered 75% of their daily diet at 0600 h. The remaining 25% of diet DM was replaced by ground corn, which was mixed with the orts that remained 2 h after feeding and placed into the rumen. Ruminal pH declined linearly with time after feeding, and this decrease was greater during the SARA challenges. Ruminal lactate increased linearly with repeated SARA challenges. Concentrations of total ruminal VFA increased linearly after feeding, and increases were greater when cows were challenged. No differences were observed due to SHSL inclusion. The model induced SARA, but partial replacement of alfalfa, corn silage, corn, and SBM by SHSL did not influence responses to SARA challenges.     

Effect of forage to concentrate ratio and intake level on utilization of early vegetative alfalfa silage by dairy cows.

Two experiments were conducted to measure the effects of intake and forage: grain ratio on utilization of early maturity alfalfa silage in dairy cows. In Experiment 1, diets with three forage: concentrate ratios (percentage of silage, percentage NDF): low (56, 28.3), medium (71, 31.0), or high (86, 33.4) were fed ad libitum to six lactating, ruminally cannulated cows in a replicated 3 x 3 Latin square. The same diets were then fed at 1.3 x maintenance intake to six gestating dry cows. Dairy milk yield and percentage and yield of milk protein and casein were higher for cows fed the low silage diet than for cows receiving other treatments. Fat percentage and yield were not different among diets. Lactating cows consumed more DM on low silage (23.0 kg/d) than on medium or high silage diets (21.4 kg), but NDF intake as percentage of BW was higher for the high silage diet. Digestibility of DM in the lactating (70.7, 69.9, and 67.5% for low, medium, and high) and dry cows (76.7, 73.5, and 69.0%, respectively) decreased as the level of silage increased. Depression in digestibility was greater as dietary concentrate increased. Cows fed the high silage diet had a faster fractional passage rate of solids and higher rumen fill. Digestion of concentrate cell walls appeared to be depressed more than alfalfa cell walls as intake increased.     

Effect of low level monensin supplementation on the production of dairy cows fed alfalfa silage

Effectiveness of low level monensin supplementation on N utilization in lactating dairy cows fed alfalfa silage was assessed using 48 multiparous Holsteins. Cows were fed a covariate diet [% of dry matter (DM): 56% alfalfa silage, 39% ground high moisture corn, 3% soybean meal, 1% ground corn, 1% vitamin-mineral supplements] for 2 wk, then grouped by days in milk into blocks of 4. Cows were randomly assigned within blocks to 1 of 4 diets that were fed for 10 wk: 1) control (covariate diet), 2) control plus 3% fish meal (replacing DM from high moisture corn), 3) monensin (10 mg/kg DM), and 4) monensin plus 3% fish meal. Diets 1 and 3 averaged 16.7% crude protein (25% from free AA in alfalfa silage); diets 2 and 4 averaged 18.5% crude protein. Monensin intake averaged 16 mg/d on diets 1 and 2 (due to contamination) and 248 mg/d on diets 3 and 4. There was no effect of fish meal or monensin on DM intake. However, weight gain and yield of milk, protein, and SNF increased with fish meal feeding, indicating metabolizable protein limited production. Feeding monensin increased blood glucose but reduced yield of 3.5% fat-corrected milk, milk fat content and yield, and milk protein content and yield. Apparent N efficiency was greatest on monensin (diet 3) but lowest on monensin plus fish meal (diet 4). Fish meal reduced blood glucose concentration and apparent N efficiency, and increased concentrations of milk and blood urea. Monensin increased ruminal propionate concentration and decreased concentration of acetate and butyrate and acetate:propionate in ruminally cannulated cows fed the experimental diets. However, these changes were small, suggesting that too little monensin was fed. Fish meal reduced ruminal total amino acid (AA) but monensin did not alter ruminal NH(3) or total AA. Both fish meal and monensin increased NH(3) formation from casein AA using ruminal inoculum from the cannulated cows. There was no evidence from this trial that feeding 250 mg of monensin per day to lactating cows improved N utilization by reducing ruminal catabolism of the large amounts of free AA in alfalfa silage.