Using brown midrib 6 dwarf forage sorghum silage and fall-grown oat silage in lactating dairy cow rations

Double cropping and increasing crop diversity could improve dairy farm economic and environmental sustainability. In this experiment, corn silage was partially replaced with 2 alternative forages, brown midrib-6 brachytic dwarf forage sorghum (Sorghum bicolor) or fall-grown oat (Avena sativa) silage, in the diet of lactating dairy cows. We investigated the effect on dry matter (DM) intake, milk yield (MY), milk components and fatty acid profile, apparent total-tract nutrient digestibility, N utilization, enteric methane emissions, and income over feed cost. We analyzed the in situ DM and neutral detergent fiber disappearance of the alternative forages versus corn silage and alfalfa haylage. Sorghum was grown in the summer and harvested in the milk stage. Oats were grown in the fall and harvested in the boot stage. Compared with corn silage, neutral detergent fiber and acid detergent fiber concentrations were higher in the alternative forages. Lignin content was highest for sorghum silage and similar for corn silage and oat silage. The alternative forages had less than 1% starch compared with the approximately 35% starch in the corn silage. Ruminal in situ DM effective degradability was similar, although statistically different, for corn silage and oat silage, but lower for sorghum silage. Diets with the alternative forages were fed in a replicated 3 × 3 Latin square design experiment with three 28-d periods and 12 Holstein cows. The control diet contained 44% (DM basis) corn silage. In the other 2 diets, sorghum or oat silages were included at 10% of dietary DM, replacing corn silage. Sorghum silage inclusion decreased DM intake, MY, and milk protein content but increased milk fat and maintained energy-corrected MY similar to the control. Oat silage had no effect on DM intake, MY, or milk components compared to the control. The oat silage diet increased apparent total-tract digestibility of dietary nutrients, except starch, whereas the sorghum diet slightly decreased DM, organic matter, crude protein, and starch digestibility. Cows consuming the oat silage diet had higher milk urea N and urinary urea N concentrations. Milk N efficiency was decreased by the sorghum diet. Diet did not affect enteric methane or carbon dioxide emissions. This study shows that oat silage can partially replace corn silage at 10% of the diet DM with no effect on MY. Brown midrib sorghum silage harvested at the milk stage with <1% starch may decrease DM intake and MY in dairy cows.     

Dry matter and nutritional losses during aerobic deterioration of corn and sorghum silages as influenced by different lactic acid bacteria inocula

The economic damage that results from aerobic deterioration of silage is a significant problem for farm profitability and feed quality. This paper quantifies the dry matter (DM) and nutritional losses that occur during the exposure of corn and sorghum silages to air over 14 d and assesses the possibility of enhancing the aerobic stability of silages through inoculation with lactic acid bacteria (LAB). The trial was carried out in Northern Italy on corn (50% milk line) and grain sorghum (early dough stage) silages. The crops were ensiled in 30-L jars, without a LAB inoculant (C), with a Lactobacillus plantarum inoculum (LP), and with a Lactobacillus buchneri inoculum (LB; theoretical rate of 1 × 10⁶ cfu/g of fresh forage). The pre-ensiled material, the silage at silo opening, and the aerobically exposed silage were analyzed for DM content, fermentative profiles, yeast and mold count, starch, crude protein, ash, fiber components, 24-h and 48-h DM digestibility and neutral detergent fiber (NDF) degradability. The yield and nutrient analysis data of the corn and sorghum silages were used as input for Milk2006 to estimate the total digestible nutrients, net energy of lactation, and milk production per Mg of DM. The DM fermentation and respiration losses were also calculated. The inocula influenced the in vitro NDF digestibility at 24 h, the net energy for lactation (NE_L), and the predicted milk yield per megagram of DM, whereas the length of time of air exposure influenced DM digestibility at 24 and 48 h, the NE_L, and the predicted milk yield per megagram of DM in the corn silages. The inocula only influenced the milk yield per megagram of DM and the air exposure affected the DM digestibility at 24 h, the NE_L, and the milk yield per megagram of DM in the sorghum silages. The milk yield, after 14 d of air exposure, decreased to 1,442, 1,418, and 1,277 kg/Mg of DM for C, LB, and LP corn silages, respectively, compared with an average value of 1,568 kg of silage at opening. In the sorghum silages, the milk yield, after 14 d of air exposure, decreased to 1,226, 1,278, and 1,250 kg/Mg of DM for C, LB, and LP, respectively. When the estimated milk yield per megagram of harvested DM of corn and sorghum silage were related to mold count, it was shown that the loss of potential milk production occurred when the mold count exceeded 4 log cfu/g of silage, and it was almost halved when the mold count reached values greater than 8 log cfu/g of silage. Inoculation with L. buchneri, at a rate of 1 × 10⁶ cfu/g of fresh forage, enhanced the stability of the silage after exposure to air, and, consequently, contributed to maintaining the nutritional value of the harvested forage over time, for air exposure up to 7 d.     

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

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

Replacing alfalfa silage with tannin-containing birdsfoot trefoil silage in total mixed rations for lactating dairy cows

Two lactation trials were conducted comparing the feeding value of silages made from birdsfoot trefoil (BFT, Lotus corniculatus L.) that had been selected for low (BFTL), medium (BFTM), and high (BFTH) levels of condensed tannins (CT) to an alfalfa silage (AS) when fed as the principal forage in total mixed rations. Diets also included corn silage, high-moisture shelled corn, soybean meal, soy hulls, and supplemental fat. In trial 1, 32 lactating Holstein cows were blocked by days in milk, assigned to treatment sequences in 8 balanced 4 × 4 Latin squares, and fed 50% dietary dry matter from AS or 1 of 3 BFT silages containing 0.6, 1.2, or 1.7% CT. Diets averaged 17.5 to 19.5% crude protein and 26% neutral detergent fiber on a dry matter basis. Data were collected over the last 2 wk of each 4-wk period. Intakes were 1.3 to 2.8 kg of dry matter/d greater on BFT than on AS and cows gained 0.5 kg of body weight/d on BFT diets while losing 0.14 kg of body weight/d on the AS diet; this resulted in greater milk per dry matter intake (DMI) on AS. Linear effects indicated true protein yield and milk urea nitrogen declined with increasing CT concentration and quadratic effects indicated DMI, energy-corrected milk, and fat yield were increased at intermediate CT concentration. True protein yield and apparent N-efficiency were greater, and milk urea nitrogen lower, on all BFT diets than on AS. In trial 2, 50 lactating Holstein cows were fed a covariate AS diet for 2 wk and then blocked by parity and days in milk and randomly assigned to 1 of 5 diets that were fed continuously for 12 wk. Diets contained (dry matter basis) 48% AS, 16% AS plus 32% of 1 of 3 BFT silages with 0.5, 0.8, or 1.5% CT, or 48% of an equal mixture of each BFT silage. Diets averaged 16.5% crude protein and 30% neutral detergent fiber. Intake and milk yield tended to be lower on AS than BFT, but body weight gains averaged 0.6 kg/d on all diets. Cows fed any of the BFT silages had reduced milk urea nitrogen and ruminal ammonia and reduced urinary N excretion. Feeding the BFT mixture reduced concentrations of milk true protein and milk urea nitrogen and depressed apparent nutrient digestibility. Among diets containing the individual BFT silages, linear reductions in DMI and yield of milk, fat, true protein, lactose, and SNF were observed with increasing CT concentration. By contrast, a previous trial with the same BFT populations showed that substituting BFTH silage containing 1.6% CT for AS in rations containing 60% silage dry matter had no effect on intake, increased yield of milk, energy-corrected milk and milk components, elevated protein use-efficiency, but with a more modest reduction in milk urea nitrogen and urinary N excretion. Silage analyses suggested that the inconsistent responses among trials were related to growth environment or ensiling effects that altered tannin-protein interactions in BFT silage. Differences in diet formulation among trials may have also influenced responses. Results from the current and previous trials indicate further work is needed to identify optimum tannin levels in forages.     

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.     

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.     

Forage intake,meal patterns,and milk production of lactating dairy cows fed grass silage or pea-wheat bi-crop silages

This study investigated the feed intake, milk production, and plasma nutrient status in dairy cows fed inter-cropped pea-wheat (bi-crop) silages comprised of contrasting ratios of pea to wheat. Spring peas (cv. Magnus) and wheat (cv. Axona) sown at either high (75:25) or low (25:75) pea inclusion rates were harvested after 13 (Cut 1) or 15 (Cut 2) wk. Eighteen Holstein-Friesian cows between wk 9 and 10 of lactation were used in a cyclical changeover design with three 28-d periods. Cows were fed the bi-crop silages and 6 kg of concentrates or second-cut grass silage supplemented with 6 (GS6) or 9 (GS9) kg/d of concentrates. Forage intakes were higher when bi-crops were fed (10.3 to 11.4 kg dry matter [DM]/d) than when grass silage was fed (8.6 kg DM/d). Total DM intake was similar among cows fed the bi-crop silages and GS9 diets, but intakes for GS6 were at least 1.7 kg DM/d lower. Increasing the pea inclusion rate increased the crude protein (CP) content of the ration, but it did not enhance forage quality or animal performance. The rate of intake of the different forages was similar, so that the higher intakes of bi-crop silages were associated with more time spent at the feedbunk and an increased number of meals. Diet digestibility ranged from 531 to 650 g/kg, and the highest value was given by the Cut 1 bi-crop silage diet. Milk yield tended to be similar for cows fed the Cut 2 bi-crop and GS9 diets, and these values were at least 1.7 kg higher than those for cows fed on other treatments. Generally, the bi-crop diets resulted in higher milk fat contents and lower polyunsaturated fatty acid contents. Milk protein content was highest for cows fed the GS9 diet. Blood metabolite content was unaffected by treatment except for blood urea nitrogen content, which was higher in cows fed the bi-crop silages, reflecting reduced N-use efficiency with these diets. The study showed that pea-wheat bi-crop silages can be used to replace moderate-quality grass silage in dairy cow rations, but their role as alternatives to high-quality forages requires additional investigation.     

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.     

Methane production,digestion, ruminal fermentation,nitrogen balance,and milk production of cows fed corn silage- or barley silage-based diets

This study evaluated the effects of replacing barley silage (BS) with corn silage (CS) in dairy cow diets on enteric CH₄ emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio 60:40; dry matter basis) with the forage portion consisting of either barley silage (0% CS; 0% CS and 54.4% BS in the TMR), a 50:50 mixture of both silages (27% CS; 27.2% CS and 27.2% BS in the TMR), or corn silage (54% CS; 0% BS and 54.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of BS) also involved increasing the proportion of corn grain (at the expense of barley grain). Intake and digestibility of dry matter and milk production increased linearly as the proportion of CS increased in the diet. Increasing dietary CS proportion decreased linearly the acetate molar proportion and increased linearly that of propionate. Daily CH₄ emissions tended to respond quadratically to increasing proportions of CS in the diet (487, 540, and 523 g/d for 0, 27, and 54% CS, respectively). Methane production adjusted for dry matter or gross energy intake declined as the amount of CS increased in the diet; this effect was more pronounced when cows were fed the 54% CS diet than the 27% CS diet. Increasing the CS proportion in the diet improved N utilization, as reflected by decreases in ruminal ammonia concentration and urinary N excretion and higher use of dietary N for milk protein secretion. Total replacement of BS with CS in dairy cow diets offers a strategy to decrease CH₄ energy losses and control N losses without negatively affecting milk performance.     

Evaluation of pearl millet and field peas plus triticale silages for midlactation dairy cows.

A mixture of field peas and triticale was planted in spring, harvested as silage, and followed by a double crop of pearl millet, which also was harvested as silage. Eighteen Holstein cows were fed diets based on pea with triticale, pearl millet, or alfalfa plus corn silages. Dry matter digestibility of the pea with triticale diet was higher than for control (71.1 vs. 66.9%), but DM digestibility was not different between control and pearl millet diets. Milk production was not affected by diets containing pea with triticale or pearl millet compared with control diets (25.2, 23.2, and 24.5 kg/d). Cows fed pea with triticale produced milk with a higher concentration of fat (4.59 vs. 3.35%) and more FCM (27.3 vs. 22.1 kg/d) than those fed the control diet. However, cows fed the control diet gained more BW than those receiving pea with triticale or pearl millet diets. Partitioning of energy between body stores and milk production was different between cows fed pea with triticale and control diets; however, total energy use was not different (32.4 vs. 30.5 Mcal of NE(L)/d). Differences in energy partitioning may have been caused partly by differences in ruminal fermentation of the respective diets.     

Effects of an exogenous protease on the fermentation and nutritive value of corn silage harvested at different dry matter contents and ensiled for various lengths of time

The objective of this experiment was to evaluate the effects of adding an experimental protease to corn plants harvested at different maturities on silage fermentation and in vitro ruminal starch digestibility (IVSD). Corn plants were harvested at maturities resulting in plants with 31 or 40% dry matter (DM). Plants were chopped, kernel processed, and treated with (1) only a 0.1 M phosphate buffer (pH 5.5, 5% vol/wt of fresh forage), (2) buffer with protease to obtain a final concentration of 20 mg of protease/kg of wet forage, and (3) buffer with protease to obtain a final concentration of 2,000 mg of protease/kg of wet forage. Treated forages (about 500 g) were ensiled in nylon-polyethylene pouches and stored between 21 and 23°C for 0, 45, 90, and 150 d. Data were analyzed as a 2 × 3 × 4 factorial arrangement of treatments, with the main effects of harvest DM, dose of protease, days of ensiling, and their interactions. The treatment with the highest dose of protease resulted in more robust fermentations across harvest DM with higher concentrations of lactic and acetic acids compared with untreated silage. Concentrations of soluble protein (% of crude protein) increased with time of ensiling, regardless of DM content at harvest. However, averaged over both harvest DM contents, it increased by 37% for silages treated with the high dose of protease compared with an average 11% increase for untreated silages and silage treated with the low dose of protease, between d 0 and 45. Averaged over both harvest DM contents, the concentration of soluble protein peaked in silages treated with the high dose of protease after 45 d of ensiling, whereas it peaked at d 90 in untreated silages and silage treated with the low dose of protease. Similar changes occurred in the concentration of NH₃-N due to length of ensiling and treatment with protease. In fresh forages, the concentration of starch for early- and late-harvested forages was similar, but IVSD was lower in the latter. After 45 d of ensiling, IVSD was highest in both early- and late-harvested silages that were treated with the high level of protease. After 150 d of ensiling, IVSD was similar among silages treated with protease, regardless of DM at harvest. Treating corn plants with a high dose of an experimental protease at harvest accelerated proteolysis during ensiling, resulting in corn silages with levels of IVSD after 45 d of ensiling that were only obtained in untreated corn silages after 150 d of ensiling.     

Production of lactating dairy cows fed alfalfa or red clover silage at equal dry matter or crude protein contents in the diet

Two Latin square trials, using 21 or 24 multiparous lactating Holstein cows, compared the feeding value of red clover and alfalfa silages harvested over 2 yr. Red clover silages averaged 2 percentage units lower in crude protein (CP) and more than 2 percentage units lower in neutral detergent fiber and acid detergent fiber than did alfalfa silage. In trial 1, diets were formulated to 60% dry matter (DM) from alfalfa, red clover silage, or alfalfa plus red clover silage (grown together); CP was adjusted to about 16.5% by adding soybean meal, and the balance of dietary DM was from ground high moisture ear corn. Nonprotein N in red clover and alfalfa-red clover silages was 80% of that in alfalfa silage. Although DM intake was 2.5 and 1.3 kg/d lower on red clover and alfalfa plus red clover, yield of milk and milk components was not different among diets. In trial 2, four diets containing rolled high moisture shelled corn were formulated to 60% DM from alfalfa or red clover silage, or 48% DM from alfalfa or red clover silage plus 12% DM from corn silage. The first three diets contained 2.9% soybean meal, and the red clover-corn silage diet contained 5.6% soybean meal; the 60% alfalfa diet contained 18.4% CP, and the other three diets averaged 16.5% CP. Nonprotein N in red clover silage was 62% of that in alfalfa silage. Intake of DM was about 2 (no corn silage) and 1 kg/d (plus corn silage) lower on red clover. Yield of milk and milk components was not different among the first three diets; however, yields of milk, total protein, and true protein were higher on red clover-corn silage with added soybean meal. Replacing alfalfa with red clover improved feed and N efficiency and apparent digestibility of DM, organic matter, neutral detergent fiber, acid detergent fiber, and hemicellulose in both trials. Net energy of lactation computed from animal performance data was 18% greater in red clover than alfalfa. Data on milk and blood urea and N efficiency suggested better N utilization on red clover.     

The effect of Lactobacillus buchneri 40788 or Lactobacillus plantarum MTD-1 on the fermentation and aerobic stability of corn silages ensiled at two dry matter contents

Whole-plant corn was harvested at 33 (normal) and 41% (moderately high) dry matter (DM) and ensiled in quadruplicate 20-L laboratory silos to investigate the effects of Lactobacillus buchneri 40788 (LB) or L. plantarum MTD-1 (LP) alone, or in combination, on the fermentation and aerobic stability of the resulting silage. Aerobic stability was defined as the amount of time after exposure to air for the silage temperature to reach 2°C above ambient temperature. The chopped forage was used in a 2 × 2 × 2 factorial arrangement of treatments: normal and moderately high DM contents, LB at 0 (untreated) or 4 × 10⁵ cfu/g of fresh forage, and LP at 0 or 1 × 10⁵ cfu/g. After 240 d of ensiling, corn silage harvested at the moderately high DM had higher pH, higher concentrations of ethanol, and more yeasts compared with the silage ensiled at the normal DM content. Inoculation with LB did not affect the concentration of lactic acid in silages with a moderately high DM, but decreased the concentration of lactic acid in the silage with normal DM. Higher concentrations of acetic acid were found in the silage treated with LB compared with those not treated with this organism. Inoculation with LP increased the concentration of lactic acid only in the silage with the normal DM content. The concentration of acetic acid was lower in silage treated with LP with a moderately high DM content, but greater in the silage treated with LP with the normal DM content when compared with silages without this inoculant. Appreciable amounts of 1,2-propanediol (average 1.65%, DM basis) were found in all silages treated with LB regardless of the DM content. The addition of L. buchneri increased the concentration of NH₃-N in silages but the addition of L. plantarum decreased it. Aerobic stability was improved in all silages treated with LB, with greater aerobic stability occurring in the silage with moderately high DM compared with silage with normal DM content. Inoculation with LP had no effect on aerobic stability. There were no interactions between L. buchneri and L. plantarum for most fermentation products or aerobic stability of the silages. This study showed that inoculating whole-plant corn with L. buchneri 40788 or L. plantarum MTD-1 has different beneficial effects on the resulting silage. There appear to be no major interactions between these organisms when added together to forage. Thus, there is potential to add both organisms simultaneously to improve the fermentation and aerobic stability of corn silage.     

Effect of feeding a corn hybrid selected for leafiness as silage or grain to lactating dairy cattle

A leafy corn hybrid was compared to a grain corn hybrid as silage and high moisture grain to evaluate dry matter intake, milk yield, and milk composition. Sixteen multiparous Holstein cows averaging 97 DIM were used in a feeding trial based on 4 x 4 Latin squares with 21-d periods. Each of four diets contained (dry basis) 8% chopped hay, 42% corn silage, 11% high moisture corn grain, 10% whole, fuzzy cottonseed, and 29% protein concentrate. One diet used leafy corn as both high moisture grain and silage. A second diet contained grain corn hybrid (control) as both high moisture grain and silage. A third diet contained leafy corn for high moisture grain and control corn for silage and the fourth diet used control corn for high moisture grain and leafy corn for silage. Cows fed diets containing leafy silage produced more milk and milk protein and ate more DM than cows fed control silage. The corn hybrid used for high moisture grain did not influence milk yield or composition. Dry matter intake was greater for cows fed the diet containing both leafy high moisture grain and leafy silage than for cows fed both control high moisture grain and control silage, but milk yield and composition were not different. When fed as silage, the leafy corn hybrid used in this experiment supported greater DMI as well as higher milk and protein yields when compared to the grain corn hybrid.     

Performance of dairy cows fed annual ryegrass silage and corn silage with steam-flaked or ground corn

Twenty-four lactating Holstein cows were used in a 6-wk randomized block design trial with a 2 × 2 factorial arrangement of treatments to determine the effects of feeding ground corn (GC) or steam-flaked corn (SFC) in diets based on either annual ryegrass silage (RS) or a 50:50 blend of annual ryegrass and corn silages (BLEND). Experimental diets contained 49.6% forage and were fed as a total mixed ration once daily for 4 wk after a 2-wk preliminary period. No interactions were observed among treatments. Cows fed BLEND consumed more dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) than those fed RS, but total-tract digestibility of OM, NDF, and ADF was greater for RS than for BLEND. No differences in nutrient intake were observed among treatments during wk 4 when nutrient digestibility was measured, but digestibility of DM and OM was greater for SFC than for GC. Cows fed BLEND tended to produce more energy-corrected milk than those fed RS, resulting in improved efficiency (kg of milk per kg of DM intake). When diets were supplemented with SFC, cows consumed less DM and produced more milk that tended to have lower milk fat percentage. Yield of milk protein and efficiency was greatest with SFC compared with GC. Blood glucose and milk urea nitrogen concentrations were similar among treatments, but blood urea nitrogen was greater for cows fed GC compared with those fed SFC. Results of this trial indicate that feeding a blend of annual ryegrass and corn silage is more desirable than feeding diets based on RS as the sole forage. Supplementing diets with SFC improved performance and efficiency compared with GC across forage sources.     

Effects of feeding grass or red clover silage cut at two maturity stages in dairy cows. 2. Dry matter intake and cell wall digestion kinetics

This study examined the effects of red clover or grass silages cut at 2 stages of growth on feed intake, cell wall digestion, and ruminal passage kinetics in lactating dairy cows. Five dairy cows equipped with rumen cannulas were used in a study designed as a 5 × 5 Latin square with 21-d periods. Diets consisted of early-cut and late-cut grass and red clover silages and a mixture of late-cut grass and early-cut red clover silages offered ad libitum. All diets were supplemented with 9 kg/d of concentrate. Ruminal digestion and passage kinetics were assessed by the rumen evacuation technique. Apparent total-tract digestibility was determined by total fecal collection. The silage dry matter intake was highest when the mixed forage diet was fed and lowest with the early-cut red clover diet. Delaying the harvest tended to decrease DMI of grass and increase that of red clover. The intake of neutral detergent fiber (NDF) and potentially digestible NDF (pdNDF) was lower but the intake of indigestible NDF (iNDF) was higher for red clover diets than for grass diets. The rumen pool size of iNDF and the ratio of iNDF to pdNDF in the rumen contents were larger, and pool sizes of NDF and pdNDF were smaller for red clover than for grass silage diets. Outflow of iNDF and the ratio of iNDF to pdNDF in digesta entering the omasal canal were larger, and the outflow of pdNDF was smaller for red clover than for grass silage diets. The digestion rate (k_d) of pdNDF was faster for red clover diets than for grass silage diets. Delaying the harvest decreased k_d for grass but increased it for red clover silage diets. Observed differences in fiber characteristics of red clover and grass silages were reflected in ruminal digestion and passage kinetics of these forages. The low intake of early-cut red clover silage could not be explained by silage digestibility, fermentation quality, or rumen fill, but was most likely related to nutritionally suboptimal composition because inclusion of moderate quality grass silage improved silage intake. Increasing the maturity of ensiled red clover does not seem to affect silage dry matter intake as consistently as that of grasses.     

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.     

Production performance,nutrient digestibility,and milk fatty acid profile of lactating dairy cows fed corn silage- or sorghum silage-based diets with and without xylanase supplementation

The objective of this study was to evaluate the effects of supplementing xylanase on production performance, nutrient digestibility, and milk fatty acid profile in high-producing dairy cows consuming corn silage- or sorghum silage-based diets. Conventional corn (80,000 seeds/ha) and brown midrib forage sorghum (250,000 seeds/ha) were planted, harvested [34 and 32% of dry matter (DM), respectively], and ensiled for more than 10 mo. Four primiparous and 20 multiparous Holstein cows were randomly assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments and 19-d periods. Treatment diets consisted of (1) corn silage-based diet without xylanase, (2) corn silage-based diet with xylanase, (3) sorghum silage-based diet without xylanase, and (4) sorghum silage-based diet with xylanase. The xylanase product was supplemented at a rate of 1.5 g of product/kg of total DM. Corn silage had higher concentrations of starch (31.2 vs. 29.2%), slightly higher concentrations of crude protein (7.1 vs. 6.8%) and fat (3.7 vs. 3.2%), and lower concentrations of neutral detergent fiber (36.4 vs. 49.0%) and lignin (2.1 vs. 5.7%) than sorghum silage. Xylanase supplementation did not affect DM intake, milk yield, milk fat percentage and yield, milk protein percentage and yield, lactose percentage and yield, and 3.5% fat-corrected milk yield. Cows consuming corn silage-based diets consumed 13% more DM (28.8 vs. 25.5 kg/d) and produced 5% more milk (51.6 vs. 48.9 kg/d) than cows consuming sorghum silage-based diets. Milk from cows consuming sorghum silage-based diets had 16% greater fat concentrations (3.84 and 3.30%) than milk from cows consuming corn silage-based diets. This resulted in 8% greater fat yields (1.81 vs. 1.68 kg/d). Silage type did not affect milk protein and lactose concentrations. Xylanase supplementation did not affect nutrient digestibility. Cows consuming corn silage-based diets showed greater DM (77.3 vs. 73.5%), crude protein (78.0 vs. 72.4), and starch (99.2 vs. 96.5%) digestibilities than cows consuming sorghum silage-based diets. In conclusion, xylanase supplementation did not improve production performance when high-producing dairy cows were fed corn silage- or sorghum silage-based diets. In addition, production performance can be sustained by feeding sorghum silage in replacement of corn silage.     

Effects of replacement of late-harvested grass silage and barley with early-harvested silage on milk production and methane emissions

This study evaluated the effects of gradual replacement of a mixture of late-cut grass silage (LS) and barley with early-cut grass silage (ES) on milk production, CH₄ emissions, and N utilization in Swedish Red cows. Two grass silages were prepared from the same primary growth of timothy grass sward but harvested 2 wk apart [11.0 and 9.7 MJ of metabolizable energy/kg of dry matter (DM)]. Four diets, fed as a total mixed ration, were formulated to meet the metabolizable energy and protein requirements of 35 kg of energy-corrected milk (ECM) by gradually replacing a mixture of LS and barley with ES (0, 33, 67, and 100% of the forage component of the diet), whereas the proportion of barley decreased from 47.2 to 26.6% of diet DM. Expeller canola meal was used as a protein supplement. Sixteen Swedish Red cows were used in 4 replicated 4 × 4 Latin squares. Cows were offered diets ad libitum and milked twice daily. Each period of 28 d comprised 14 d of diet adaptation followed by 14 d of data collection. Intake and milk yield were recorded daily, and milk samples were collected on d 19 to 21 and d 26 to 28 of each period. Diet digestibility was determined by grab sampling using indigestible neutral detergent fiber as an internal marker. Gas emissions were measured using the GreenFeed system (C-Lock Inc., Rapid City, SD). Dry matter intake (DMI) linearly decreased from 22.6 to 19.3 kg/d as the proportion of ES increased in the diet. The ECM yield did not differ among treatments, but milk protein yield decreased with increasing proportion of ES in the diet. Because of reduced DMI with increasing ES, feed efficiency (ECM/DMI) improved with an increased proportion of ES in the diet. Nitrogen efficiency (milk N/N intake) did not change despite a linear increase in milk urea N concentration from 9.7 (LS alone) to 11.9 mg/dL (ES alone) with graded replacement of LS and barley by ES in the diet. Lower DMI responses in ES diets were partly compensated for by increased organic matter digestibility (656 g/kg of DM for LS alone; 715 g/kg of DM for ES alone) related to improved forage digestibility at early harvesting. Total CH₄ emissions and CH₄ intensity (CH₄/ECM) were not influenced by diet, but CH₄ yield (CH₄/DMI) increased linearly from 19.5 to 23.0 g/kg of DMI with greater inclusion of ES in the diet. In conclusion, replacing LS and barley with ES improved the conversion of feed to milk without increasing CH₄ emissions or compromising N efficiency.     

Effects of tallow in diets based on corn silage or alfalfa silage on digestion and nutrient use by lactating dairy cows

Six multiparous Holstein cows (average 31 days in milk; 36.3 kg/d of milk) fitted with ruminal cannulas were used in a 6 x 6 Latin square with 21-d periods to investigate the effects of diets that varied in forage source and amount of supplemental tallow. Isonitrogenous diets in a 2 x 3 factorial arrangement were based on either high corn silage (40:10 corn silage to alfalfa silage, % of dry matter) or high alfalfa silage (10:40 corn silage to alfalfa silage, % of dry matter) and contained 0, 2, or 4% tallow. Intakes of dry matter and total fatty acids were lower when cows were fed the high corn silage diet. Tallow supplementation linearly decreased dry matter intake. Milk yield was unaffected by diet; yields of milk fat and 3.5% fat-corrected milk were higher for the high alfalfa silage diet but were unaffected by tallow. Milk fat percentage was higher for the high alfalfa silage and tended to decrease when tallow was added to the high corn silage diet. Contents of trans-C18:1 isomers in milk fat were increased by high corn silage and tallow, and tended to be increased more when tallow was fed in the high corn silage diet. Ruminal pH and acetate:propionate were lower when high corn silage was fed. Ruminal acetate:propionate decreased linearly as tallow increased; the molar proportion of acetate was decreased more when tallow was added to the high corn silage diet. Ruminal liquid dilution rates were higher for the alfalfa silage diet; ruminal volume and solid passage rates were similar among diets. Total tract apparent digestibilities of dry matter, organic matter, crude protein, starch, energy, and total fatty acids were unaffected by diet. Digestibilities of neutral detergent fiber, acid detergent fiber, hemicellulose, and cellulose were lower when high corn silage was fed. The high alfalfa silage diet increased intakes of metabolizable energy and N, and increased milk energy and productive N. Tallow decreased the amount of N absorbed but had few other effects on utilization of energy or N. Tallow linearly increased concentrations of nonesterified fatty acids and cholesterol in plasma; cholesterol was increased by high alfalfa silage. Overall, forage source had more pronounced effects on production and metabolism than did tallow supplementation. Few interactions between forage source and tallow supplementation were detected except that ruminal fermentation and milk fat content were affected more negatively when tallow was fed in the high corn silage diet.