Effect of corn hybrid and chop length of whole-plant corn silage on digestion and intake by dairy cows

The objectives of this experiment were to study the effects of corn hybrid and chop length of whole-plant corn silage (WPCS) on intake, and to quantify ruminal digestive processes that could help to identify factors limiting dry matter intake (DMI). Eight lactating cows and 4 dry cows fitted with a ruminal cannula were randomly assigned to 4 treatments in a 4 x 4 Latin square design with replications for lactating cows and without for ruminally cannulated cows. Treatments were fed in a total mixed ration (TMR) containing 75% WPCS and 25% concentrate. The 4 WPCS differed in the characteristics of 2 conventional hybrids, less degradable vs. more degradable in the rumen and in the chop length, fine vs. coarse. The DMI was measured for all cows, and digestion measurements and chewing activities were recorded with the cannulated cows. With lactating cows, DMI and milk yield varied with corn hybrids but not with chop length. The less degradable hybrid in the rumen was the less ingested. Dry matter intake of dry ears followed the same trend, but the differences between hybrids were lower than that observed with the lactating cows and not significant. Dry matter digestibility in the total tract and rumen fill were not different between hybrids. Ruminal mean retention time was greater for the least degradable hybrid. The rumen fill capacity could explain intake differences between hybrids. Ingestive mastication strongly reduced particle size, and the efficiency of particle size reduction was more important with the coarsely chopped WPCS than the finely chopped ones. The small differences in particle size of material entering the rumen after mastication of WPCS during eating might explain the lack of response for decreasing chop length. Because the rumen fill decreased with the decrease in chop length, rumen fill could not be the only factor responsible for DMI control of WPCS.     

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.     

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.     

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.     

Influence of corn variety and cutting height on nutritive value of silage fed to lactating dairy cows

Two corn varieties predicted to differ in digestibility were harvested at 2 cutting heights (10.2 or 30.5 cm) to determine effects on the nutrient content of the resulting silage, nutrient intake, nutrient digestibility, and production of lactating cows fed such corn silage originally harvested at two-thirds milk line. Acid detergent fiber (ADF) concentration was higher and in vitro true dry matter (DM) digestibility (IVTDMD) was lower for the variety predicted to have average digestibility. An interaction was observed between variety and cutting height because of decreased ADF and increased IVTDMD for the average digestibility variety cut at 30.5 vs. 10.2 cm; no differences were observed for the higher digestibility variety at each cutting height. When silages were fed to 32 Holstein cows in a 5-wk randomized design trial, DM intake, milk yield, and milk composition were similar. There was an interaction between variety and cutting height for DM intake and total tract apparent digestibility of DM, crude protein, and neutral detergent fiber because of lower intake and digestibility for the diets containing either the high cut, average quality variety or low cut, higher quality variety. These results suggest that increasing the cutting height to 30.5 cm does not improve silage quality or improve milk yield of cows. Although the 2 varieties selected for this trial were predicted to differ in digestibility, these differences were not great enough to influence milk yield or composition of lactating cows.     

Effect of length of cut and kernel processing on use of corn silage by lactating dairy cows

Forty Holstein cows were used in an 8-wk randomized block design trial to determine the effects of theoretical length of cut (TLC) and kernel processing (KP) of whole plant corn silage on nutrient intake and digestibility, milk yield, and milk composition. Corn was harvested at three-quarters milk line stage of maturity at TLC of 1.90 or 2.54 cm. At each TLC, corn was KP at either 2 or 8 mm roll clearance. The control was harvested at 1.90 cm without KP. Corn silage provided 38% of the dietary dry matter (DM) in the experimental diets. Intake of DM and nutrients was similar among treatments. Apparent digestibility of DM and acid detergent fiber (ADF) increased with increasing TLC. Fiber digestibility was improved by KP compared with unprocessed corn silage. Starch digestibility was greater for corn silage KP at 2 vs. 8 mm. Apparent digestibility of DM, crude protein, and ADF was lowest for the diet containing silage harvested at 2.54 cm TLC and KP at 8 mm, resulting in an interaction of TLC and KP. No differences were observed in DM intake (DMI) among treatments. An interaction of TLC and KP was observed, however, for yield of milk protein and energy-corrected milk (ECM) and efficiency of converting DMI to ECM because of lower yield for diets containing silage harvested at 2.54 cm TLC and KP at 8 mm. Results of this trial indicate that as TLC increases, aggressive KP is necessary to maintain nutrient digestibility and performance of lactating dairy cows.     

The effects of feeding α-amylase-enhanced corn silage with different dietary starch concentrations to lactating dairy cows on milk production,nutrient digestibility,and blood metabolites

Corn silage is one of the most common ingredients fed to dairy cattle. Advancement of corn silage genetics has improved nutrient digestibility and dairy cow lactation performance in the past. A corn silage hybrid with enhanced endogenous α-amylase activity (Enogen, Syngenta Seeds LLC) may improve milk production efficiency and nutrient digestibility when fed to lactating dairy cows. Furthermore, evaluating how Enogen silage interacts with different dietary starch content is important because the ruminal environment is influenced by the amount of rumen fermentable organic matter consumed. To evaluate the effects of Enogen corn silage and dietary starch content, we conducted an 8-wk randomized complete block experiment (2-wk covariate period, 6-wk experimental period) with a 2 × 2 factorial treatment arrangement using 44 cows (n = 11/treatment; 28 multiparous, 16 primiparous; 151 ± 42 d in milk; 668 ± 63.6 kg of body weight). Treatment factors were Enogen corn silage (ENO) or control (CON) corn silage included at 40% of diet dry matter and 25% (LO) or 30% (HI) dietary starch. Corn silage used in CON treatment was a similar hybrid as in ENO but without enhanced α-amylase activity. The experimental period began 41 d after silage harvest. Feed intake and milk yield data were collected daily, plasma metabolites and fecal pH were measured weekly, and digestibility was measured during the first and final weeks of the experimental period. Data were analyzed using a linear mixed model approach with repeated measures for all variables except for body condition score change and body weight change. Corn silage, starch, week, and their interactions were included as fixed effects; baseline covariates and their interactions with corn silage and starch were also tested. Block and cow served as the random effects. Plasma glucose, insulin, haptoglobin, and serum amyloid A concentrations were unaffected by treatment. Fecal pH was greater for cows fed ENO versus CON. Dry matter, crude protein, neutral detergent fiber, and starch digestibility were all greater for ENO than CON during wk 1, but differences were less by wk 6. The HI treatments depressed neutral detergent fiber digestibility compared with LO. Dry matter intake (DMI) was not affected by corn silage but was affected by the interaction of starch and week; in wk 1, DMI was similar but by wk 6, cows fed HI had 1.8 ± 0.93 kg/d less DMI than LO cows. Milk, energy-corrected milk, and milk protein yields were 1.7 ± 0.94 kg/d, 1.3 ± 0.70 kg/d, and 65 ± 27 g/d greater for HI than LO, respectively. In conclusion, ENO increased digestibility but it did not affect milk yield, component yields, or DMI. Increasing dietary starch content improved milk production and feed efficiency without affecting markers of inflammation or metabolism.     

Varying dietary fiber for lactating cows fed corn and barley silages

Seventy-five lactating cows were in three experiments to determine the effect of dietary fiber content on ration intake, milk and milk fat production, ration digestibility, nitrogen utilization, and ruminal volatile fatty acids. With corn or barley silage as the source of forage, four treatment groups consumed rations averaging 11.8, 14.5, 17.5, and 20.6% crude fiber and 14.3, 17.5, 20.0, and 23.9% acid detergent fiber dry basis. Fiber intake was controlled by the amount and fiber content of concentrate offered or by silages with different grain content. With corn silage, dry matter intake was not altered by dietary fiber, but dry matter intake was lower when additional fiber was fed with barlev silage. Linear regressions best described effects of dietary fiber on milk production and milk fat content. Milk production declined .39 and .36 kg and milk fat test increased .072 and .067% for each percentage increase in crude and acid detergent fiber. Ration digestibility, determined by lignin ratio, was less for barley silage than corn silage. Narrowing acetate: propionate ratios were evident when dietary fiber was lowered. From these experiments with silage based rations, either crude or acid-detergent fiber content of forage adequately describes feeds to serve as a basis for practically balancing rations for lactating cows.     

Effect of kernel processing and particle size of whole-plant corn silage with vitreous endosperm on dairy cow performance

Kernel processing and theoretical length of cut (TLOC) of whole-plant corn silage (WPCS) can affect feed intake, digestibility, and performance of dairy cows. The objective of this study was to evaluate for lactating dairy cows the effects of kernel processing and TLOC of WPCS with vitreous endosperm. The treatments were a pull-type forage harvester without kernel processor set for a 6-mm TLOC (PT6) and a self-propelled forage harvester with kernel processor set for a 6-mm TLOC (SP6), 12-mm TLOC (SP12), and 18-mm TLOC (SP18). Processing scores of the WPCS were 32.1% (PT6), 53.9% (SP6), 49.0% (SP12), and 40.1% (SP18). Twenty-four Holstein cows (139 ± 63 d in milk) were blocked and assigned to six 4 × 4 Latin squares with 24-d periods (18 d of adaptation). Diets were formulated to contain 48.5% WPCS, 15.5% citrus pulp, 15.0% dry ground corn, 9.5% soybean meal, 6.8% low rumen degradability soybean meal, 1.8% calcium soap of palm fatty acids (FA), 1.7% mineral and vitamin mix, and 1% urea (dry matter basis). Nutrient composition of the diets (% of dry matter) was 16.5% crude protein, 28.9% neutral detergent fiber, and 25.4% starch. Three orthogonal contrasts were used to compare treatments: effect of kernel processing (PT6 vs. SP6) and effect of TLOC (particle size; SP6 vs. SP12 and SP12 vs. SP18). Cows fed SP6 produced 1.2 kg/d greater milk yield with no changes in dry matter intake, resulting in greater feed efficiency compared with PT6. Cows fed SP6 also produced more milk protein (+36 g/d), lactose (+61 g/d), and total solids (+94 g/d) than cows fed PT6. The mechanism for increased yield of milk and milk components involved greater kernel fragmentation, starch digestibility, and glucose availability for lactose synthesis by the mammary gland. However, cows fed SP6 had lower chewing time and tended to have greater levels of serum amyloid A compared with PT6. Milk yield was similar for SP6 and SP12, but SP12 cows tended to have less serum amyloid A with greater chewing time. Cows fed SP18 had lower total-tract starch digestibility and tended to have lower plasma glucose and produce less milk compared with cows fed SP12. Compared with PT6, feeding SP6 raised linear odd-chain FA concentration in milk. Similarly, a reduction of these same FA occurred for SP12 compared with SP6. Cows fed SP6 had greater proportion of milk C14:1 and C16:1 compared with PT6 and SP12. Lesser trans C18:1 followed by greater C18:0 concentrations were observed for SP12 and PT6 compared with SP6, which is an indication of more complete biohydrogenation in the rumen. Under the conditions of this study, the use of a self-propelled forage harvester with kernel processing set for a 12-mm TLOC is recommended for WPCS from hybrids with vitreous endosperm.     

Silage review: Recent advances and future technologies for whole-plant and fractionated corn silage harvesting

Over the last 25 years, whole-plant corn silage has become an important and popular feedstuff for dairy production. Copious research has been dedicated to the development and evaluation of alternatives to enhance the nutritive value of whole-plant corn silage. These efforts have been aimed at manipulating the physical and chemical characteristics of whole-plant corn silage in an effort to maximize dairy profitability. Results from this review indicate that optimization of harvest maturity, kernel processing, theoretical length of cut, and cutting height improve or maintain the nutritive value and milk production of lactating dairy cows. Technological advancements have been developed and made available to dairy producers and corn growers desiring to enhance fiber and starch digestibility of whole-plant corn silage. Future research should be directed toward further assessment of new processors available in the market and the development of assessment methods for optimization of crop processor settings, harvest efficiency, and nutritional modeling.     

Corn silage hybrid effects on intake, digestion, and milk production by dairy cows

Three corn hybrids harvested as whole-plant silage were evaluated in three separate feeding trials with lactating dairy cows. In trial 1, 24 multiparous Holstein cows were used in a replicated 4 x 4 Latin square with 28-d periods. Treatments were conventional (Pioneer 3563) and leafy (Mycogen TMF 106) corn silage hybrids, each planted at low (59,000 plants/ha) and high (79,000 plants/ha) plant populations. There were no milk production differences between treatments. Total-tract digestibility of dietary starch was higher for leafy compared with conventional corn hybrids. In trial 2, 26 multiparous Holstein cows were assigned randomly to diets containing either conventional (48% forage diet) or brown-midrib (60% forage diet) corn silage in a crossover design with 8-wk periods. Milk yield was lower, but milk fat percentage and yield were higher, for the high-forage diet containing brown-midrib corn silage. In trial 3, 24 multiparous Holstein cows were used in a replicated 4 x 4 Latin square with 28-d periods. Treatments were corn silage at two concentrations of neutral detergent fiber (Garst 8751, 39.2% NDF; Cargill 3677, 32.8% NDF) each fed in normal- (53% of dry matter) and high- (61 to 67% of dry matter) forage diets. Milk production was not different between corn hybrids. Increased concentrate supplementation increased DMI and milk production. There were minimal benefits to the feeding of leafy or low-fiber corn silage hybrids. Feeding brown-midrib corn silage in a high-forage diet increased milk fat percentage and yield compared with conventional corn silage fed in a normal-forage diet.     

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.     

Productivity of lactating dairy cows fed diets with teff hay as the sole forage

Groundwater depletion is one of the most pressing issues facing the dairy industry in arid regions. One strategy to improve the industry's drought resilience involves feeding drought-tolerant forage crops in place of traditional forage crops such as alfalfa and corn silage. The objective of this study was to assess the productivity of lactating dairy cows fed diets with teff hay (Eragrostis tef) as the sole forage. Teff is a warm-season annual grass native to Ethiopia that is well adapted to drought conditions. Nine multiparous Holstein cows (185 ± 31 d in milk; mean ± standard deviation) were randomly assigned to 1 of 3 diets in a 3 × 3 Latin square design with 18-d periods (14 d acclimation and 4 d sampling). Diets were either control, where dietary forage consisted of a combination of corn silage, alfalfa hay, and native grass hay, or 1 of 2 teff diets (teff-A and teff-B), where teff hay [13.97 ± 0.32% crude protein, dry matter (DM) basis] was the sole forage. All 3 diets were formulated for similar DM, crude protein, and nonfiber carbohydrate concentrations. Control and teff-A were matched for concentrations of neutral detergent fiber (NDF) from forage (18.2 ± 0.15% of DM), and teff-B included slightly less, providing 16.6% NDF from forage. Dry matter intake, milk and component production, body weight, body condition score, as well as DM and NDF digestibility were monitored and assessed using mixed model analysis, with significance declared at P < 0.05. Treatment had no effect on dry matter intake (28.1 ± 0.75 kg/d). Similarly, treatment had no effect on milk production (40.7 ± 1.8 kg/d). Concentrations of milk fat (3.90 ± 0.16%) and lactose (4.68 ± 0.07%) were also unaffected by treatment. Teff-A and teff-B increased milk protein concentration compared with the control (3.07 vs. 3.16 ± 0.09%). Treatment had no effect on energy-corrected milk yield (43.4 ± 1.3 kg/d), body weight, or body condition score change. Additionally, treatment had no effect on total-tract DM or NDF digestibility. Results from this study indicate that teff hay has potential to replace alfalfa and corn silage in the diets of lactating dairy cattle without loss of productivity.     

Effect of feeding macerated alfalfa silage on nutrient digestibility and milk yield in lactating dairy cows

Five feeding studies were conducted with 141 lactating Holstein cows comparing macerated and control alfalfa silage harvested at two cuttings in each of 2 yr. Overall, silage made from macerated alfalfa contained more ash (suggesting improved soil contamination); greater fiber and lower nonprotein nitrogen (NPN) content suggested greater fermentation in the silo. In a digestion study, two diets were fed containing [dry matter (DM) basis] 72% of either control or macerated second-cutting alfalfa. Apparent digestibility of neutral detergent fiber and acid detergent fiber (ADF) was increased by maceration, and similar changes in digestibility were observed with Yb or indigestible ADF as marker; indigestible ADF was used as a marker in later studies. Lactation trials were conducted with first- and second-cutting alfalfa from each year. In each study, diets were formulated from alfalfa silage plus concentrate based on processed high moisture ear corn; mean compositions were (DM basis): negative control (61% control alfalfa silage), macerated (61% macerated alfalfa silage), and positive control (50% control alfalfa silage). All diets contained 2% crude protein from either roasted soybeans or low-solubles fish meal; soybean meal was added to make the positive control isonitrogenous (but not equal in ruminal undergraded protein). Milk yield was greater on macerated than negative control in two of four trials but not different in the other two trials. Yields of milk and milk components were not different between macerated and positive control in one of four trials. Versus the negative control, milk fat synthesis was depressed on macerated alfalfa in one trial. Overall performance on macerated versus negative control indicated greater apparent digestibility of organic matter (OM), greater yield of milk, protein, and solids not fat, but lower milk fat content. Yields of milk and milk components were greater overall on positive control versus macerated. Estimation of net energy for lactation (NEL) from maintenance, milk yield, and body weight gain indicated that control and macerated alfalfa silage contained, respectively, 1.36 and 1.42 Mcal of NEL of OM, an increase of about 5% due to maceration of alfalfa in these trials.     

Effects of cutting height and maturity on the nutritive value of corn silage for lactating cows

We studied the effect of increasing the cutting height of whole-plant corn at the time of harvest from 12.7 (NC) to 45.7 (HC) cm on yield and nutritive value of silage for dairy cows. Three leafy corn silage hybrids were harvested at NC and HC at about 34% dry matter (E) and 41% DM (L) and ensiled in laboratory silos. Increasing the height of cutting lowered yields of harvested DM/ha. In addition, the concentrations of DM and starch were higher but the concentrations of lactic acid, crude protein, neutral detergent fiber (NDF), and acid detergent fiber were lower in HC than in NC. The concentration of acid detergent lignin was also lower in HC, but only in corn harvested at E. In vitro digestion (30 h) of NDF was greater in HC (50.7%) than NC (48.3%). Calculated yield of milk per tonne of forage DM was greater for HC than for NC at E but not at L. In a lactation experiment, increasing the height of cutting of another leafy corn silage hybrid, TMF29400, in general also resulted in similar changes in nutrient composition as just described. When fed to lactating dairy cows, HC corn silage resulted in tendencies for greater NDF digestion in the total tract, higher milk production and improved feed efficiency, but there were no differences in 3.5% fat corrected milk between treatments. Results of this study suggest that increasing the cutting height of whole plant corn at harvest can improve the nutritive value of corn silage for lactating dairy cows.     

Short communication: Purple corn (Zea mays L.) stover silage with abundant anthocyanins transferring anthocyanin composition to the milk and increasing antioxidant status of lactating dairy goats

The present study used 16 multiparous lactating Saanen dairy goats (body weight, 41.80 ± 2.92 kg; mean ± standard deviation) with healthy and symmetrical udders. Goats were divided into 2 blocks of 8 goats based on milk yield averaged from 75 d in milk in a randomized completed block design. The 2 study groups were the control (CSSS), in which goats were fed sticky corn stover silage, and the treatment (TPSS), in which goats were fed anthocyanin-rich purple corn (Zea mays L.) stover silage (PSS). The results indicated that the TPSS group led to an elevation in the content of milk lactose relative to the CSSS. The inclusion of anthocyanin-rich PSS had no effect on the level of 5 particular anthocyanins [i.e., cyanidin-3-glucoside, delphinidin, cyanidin, pelargonidin (Pel), as well as total anthocyanins in milk]. The pelargonidin-3-glucoside and malvidin were unable to be detected in both groups. However, the TPSS resulted in higher levels of peonidin (Peo) and malvidin-3-O-glucoside (M3G) compared with the control. Moreover, goats receiving TPSS exhibited a higher level of superoxide dismutase (SOD) in plasma and milk relative to the CSSS. Interestingly, some positive correlations were detected between the certain milk components [i.e., fat and total solids as well as fat and solids-not-fat (SNF); protein and SNF; and total solids and SNF]. In addition, the positive correlations were observed between individual anthocyanins (cyanidin-3-glucoside, delphinidin, Peo, M3G, cyanidin, and Pel) and total anthocyanins. Specifically, stronger positive correlations were noted between several antioxidant enzymes and anthocyanin composition in milk (total antioxidant capacity and Pel; SOD and Peo as well as SOD and M3G). Taken together, PSS with abundant anthocyanins can transfer anthocyanins to the milk and enhance the amount of antioxidants in lactating dairy goats.     

Inclusion of wheat and triticale silage in the diet of lactating dairy cows

The objective of this experiment was to partially replace corn silage with 2 alternative forages, wheat (Triticum aestivum) or triticale (X Triticosecale) silages at 10% of the diet dry matter (DM), and investigate the effects on dairy cow productivity, nutrient utilization, enteric CH₄ emissions, and farm income over feed costs. Wheat and triticale were planted in the fall as cover crops and harvested in the spring at the boot stage. Neutral- and acid-detergent fiber and lignin concentrations were higher in the wheat and triticale silages compared with corn silage. The forages had similar ruminal in situ effective degradability of DM. Both alternative forages had 1% starch or less compared with the approximately 35% starch in corn 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, wheat or triticale silages were included at 10% of dietary DM, replacing corn silage. Dry matter intake was not affected by diet, but both wheat and triticale silage decreased yield of milk (41.4 and 41.2 vs. 42.7 ± 5.18 kg/d) and milk components, compared with corn silage. Milk fat from cows fed the alternative forage diets contained higher concentrations of 4:0, 6:0, and 18:0 and tended to have lower concentrations of total trans fatty acids. Apparent total-tract digestibility of DM and organic matter was decreased in the wheat silage diet, and digestibility of neutral-and acid-detergent fiber was increased in the triticale silage diet. The wheat and triticale silage diets resulted in higher excretion of urinary urea, higher milk urea N, and lower milk N efficiency compared with the corn silage diet. Enteric CH₄ emission per kilogram of energy-corrected milk was highest in the triticale silage diet, whereas CO₂ emission was decreased by both wheat and triticale silage. This study showed that, at milk production of around 42 kg/d, wheat silage and triticale silage can partially replace corn silage DM and not affect DM intake, but milk yield may decrease slightly. For dairy farms in need of more forage, triticale or wheat double cropped with corn silage may be an appropriate cropping strategy.     

Effects of the dose and viability of Saccharomyces cerevisiae. 2. Ruminal fermentation,performance of lactating dairy cows,and correlations between ruminal bacteria abundance and performance measures

This study examined effects of the dose and viability of supplemented Saccharomyces cerevisiae yeast strain YE1496 on ruminal fermentation and performance of lactating dairy cows. A second objective was to examine correlations between ruminal bacteria abundance and performance measures. Four ruminally cannulated lactating cows (284 ± 18 days in milk) were assigned randomly to 1 of 4 treatment sequences in a 4 × 4 Latin square experimental design using four 21-d experimental periods. Cows were fed a nonacidotic total mixed ration comprising 22.5% starch (minimum ruminal pH >5.8), 41.7% corn silage, 7.60% wet brewers grain, and 50.7% concentrate on a dry matter (DM) basis. The diet was supplemented with no yeast (control), a low (5.7 × 10⁷ cfu/d; LLY) or high (6.0 × 10⁸ cfu/d; HLY) dose of live yeast, or a high dose of killed yeast (6.0 × 10⁸ cfu/d; killed by heating at 80°C for 1.5 h; HDY). Milk production and composition were measured twice daily from d 11 to 21 of each period, and rumen fluid samples were collected on d 21. In vivo digestibility was measured using chromic oxide as a marker. Pearson correlation analysis was used to assess whether animal performance parameters were correlated with relative abundance (RA) of ruminal bacteria. Supplemental LLY increased yields (kg/d) of milk (29.6 vs. 31.7) and milk protein (0.95 vs. 1.03), tended to increase milk fat yield (1.10 vs. 1.17) and ruminal acetate:propionate ratio (1.92 vs. 2.21), and increased in vivo apparent digestibility (%) of DM (64.5 vs. 69.1), neutral detergent fiber (NDF; 45.0 vs. 54.5), and ADF (53.1 vs. 60.9) compared with the control. Feeding HLY had no effects on milk yield compared with the control (30.0 vs. 29.6 kg/d). Feeding HDY tended to increase in vivo digestibility (%) of NDF (45.0 vs. 50.7), ADF (53.1 vs. 57.7), and the ruminal concentration of lactate (0.78 vs. 2.82 mM) but did not affect milk yield compared with the control. Dry matter and NDF digestibility correlated negatively with RA of unclassified Lachnospiraceae in both solid (r = ?0.50 and ?0.52, respectively) and liquid (r = ?0.56 and ?0.57, respectively) fractions, whereas milk yield correlated positively with RA of Lachnospiraceae [Ruminococcus] (an incompletely classified genus; r = 0.43) in the solid ruminal fraction. Supplemental LLY, HLY, or HDY increased or tended to increase DM, NDF, and ADF digestibility, but only LLY increased yields of milk, milk fat, and milk protein.     

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.