Rumen Fermentation In Dairy Cows Research Articles

Effects of replacing alfalfa hay with Moringa oleifera leaves and peduncles on intake, digestibility, and rumen fermentation in dairy cows

To study the effects of replacing alfalfa hay with Moringa oleifera leaves and peduncles in diets on intake, digestibility, and rumen fermentation in dairy cows, eight multiparous Holsteins cows with similar DIM (day in milk, 93 ± 18 d) and body weights (624 ± 38 kg) were used in a crossover design with two dietary treatments. The treatment diets contained similar concentrate mixtures and corn silage but different proportions of M. oleifera leaves and peduncles. The treatments were a (1) control diet (0% M. oleifera feed) and (2) M. oleifera diet (10.85% M. oleifera feed). The M. oleifera feed used M. oleifera leaves and M. oleifera peduncles at a ratio of 3:2 and replaced portions of alfalfa hay. The experimental period was 18 d, with 15 d for treatment adaptation and 3 d for data collection. Compared with the control diet, the dry matter intake and apparent digestibility of dry matter, crude protein, acid detergent fiber and neutral detergent fiber in the M. oleifera diet were significantly increased. No difference was observed in ruminal pH; however, the ammonia-N concentrate was lower for the M. oleifera diet than the control diet. The concentrations of total ruminal volatile fatty acids, acetate, propionate, and butyrate were higher in cows fed the M. oleifera diet than in those fed the control diet. The results of ruminal microbes showed that those consuming the M. oleifera diet had greater relative expression level of Fibrobacter succinogenes, Butyrivibrio fibrisolvens, Ruminobacter amylophilus, Streptococcus bovis, Prevotella ruminicola which were observed for the control diet than the M. oleifera diet. These results show that the M. oleifera diet can improve intake and apparent digestibility of nutrients, and rumen fermentation in dairy cows.

Effect of urea- and molasses-treated sugarcane bagasse on nutrient composition and in vitro rumen fermentation in dairy cows

The effect of urea- and molasses-treated sugarcane bagasse was studied on the chemical composition, fermentation quality, in vitro gas production and digestibility in dairy cows. The experiment followed a completely randomized design in a 2 × 2 × 2 factorial arrangement of treatments with a control (sugarcane bagasse without any treatment). Factor A was before or after the sugarcane bagasse had been fermented with substrate at 21 d, factor B was the level of urea (0% or 5%), and factor C was the level of molasses (0% or 5%). The results showed that the crude protein content of the sugarcane bagasse increased (p < 0.05) following the urea and molasses treatment, whereas treatment with urea and molasses reduced (p < 0.05) the neutral detergent fiber content and the acid detergent fiber content of the sugarcane bagasse. Moreover, after fermentation, all treatments of the sugarcane bagasse had higher gas kinetics and gas production compared with before fermentation and the control; adding urea and molasses resulted in the highest (p < 0.05) gas production from the soluble fraction (a), from the insoluble fraction (b) and the highest gas potential extent (a+b) as well as cumulative gas production. In addition, in vitro dry matter and organic matter degradability increased (p < 0.05) with the urea and molasses treatments. In conclusion, utilization of 5% urea and 5% molasses as ingredients in sugarcane bagasse treatments would be effective in enhancing the nutritive value and in vitro rumen fermentation. Therefore, sugarcane bagasse treated with urea and molasses could be suitable for use as a roughage source for dairy cattle.

Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined With a Moderate Concentrate Feed Supply on Rumen Fermentation of Dairy Cows.

Simple SummaryIn temperate climate zones, cows are in spring traditionally transitioned from a silage and concentrate- ration to a pasture-based ration. This transition requires complex nutritional and metabolic adaptions for the cow, resulting in a lower feed intake with consequences on energy metabolism. Normally concentrate feed is supplied to support the cows after transition to pasture. Depending on weather influences and growing stage, grass contains high amounts of fast fermentable carbohydrates and low amounts of physical effective fiber. In a previous trial, pasture feeding combined with low amounts of concentrate supply did not prevent an energy shortage after transition to pasture but led to changes in ruminal fermentation patterns indicating a possible risk for rumen health. However, the impact of ration change has not been extensively researched so far when moderate concentrate feed was supplied moderately in order to prevent an energy deficiency. To investigate the influences different rumen variables were documented, using continuous pH measuring devices and weekly diurnal fermentation assessments in rumen fistulated animals. Influence on rumen epithelial morphology was measured by the collection of rumen papillae biopsies and subsequent surface area, as well as histopathological analyses. With the help of this data, a greater understanding of the adaption period of the animals during transition from confinement to pasture is made possible.In spring, transition from a total mixed ration (TMR) to pasture requires rumen adaptions for the cow. It had been shown that transition period does not necessarily mean an increased risk for subacute ruminal acidosis (SARA). After adaption to pasture, however, supplying low amounts of concentrate did indicate increased risk, but caused no adverse effects on rumen morphology and absorption capacity. The present study aimed to investigate the effect of transition, and how a supply of 4.5 kg dry matter concentrate·cow−1day−1 during fulltime grazing influenced different rumen parameters. During a 12-week trial eleven rumen-cannulated dairy cows were observed during transition from confinement to pasture (PG; n = 6) and compared to cows fed TMR indoors (CG; n = 5). The CG stayed on a TMR based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter basis), whereas the PG slowly switched to a pasture-based ration (week 0 and 1 = TMR, week 2 = TMR and 3 h pasture·day−1, week 3 and 4 = TMR and 12 h pasture·day−1, and week 5 to 11 = pasture combined with 4.5 kg DM concentratecow−1·day−1). Papillae surface area decreased during transition and increased again during fulltime grazing, while the fractional absorption rate of volatile fatty acids (VFA) was not influenced. This suggests only a limited effect of papillae surface area on VFA absorption rate. Feeding changes resulted in different fermentation profiles of VFA. Changing ratio of starch to sugar during transition to fulltime grazing plus concentrate supply did not lead to lower rumen pH. In conclusion, the concentrate supply combined with high fermentable grass during fulltime grazing increased papillae surface area but did not affect absorption rate or rumen pH, so that risk for SARA was not increased.

Effect of concentrate level on enteric methane emissions, production performance, and rumen fermentation of Jersey cows grazing kikuyu-dominant pasture during summer

The effect of concentrate feeding level on enteric CH4 emissions from cows grazing medium quality summer pasture is yet to be investigated. Sixty multiparous Jersey cows (9 rumen-cannulated) were used in a randomized complete block design study (with the cannulated cows in a 3 × 3 Latin square design) to investigate the effect of concentrate feeding level (0, 4, and 8 kg/cow per day; as-fed basis) on enteric CH4 emissions, production performance, and rumen fermentation of dairy cows grazing summer pasture (17 cows plus 3 cannulated cows per treatment). Enteric CH4 emissions were measured from 11 cows per treatment group during one 7-d measurement period using the sulfur hexafluoride tracer gas technique. Pasture dry matter intake (DMI) was determined parallel with the CH4 measurement period using TiO2 as an external marker, and milk yield, milk composition, cow condition, and pasture pre- and postgrazing measurements were also recorded. Daily total DMI (11.2 to 15.6 kg/cow), milk yield (9.1 to 18.2 kg/cow), energy-corrected milk (ECM; 11.2 to 21.6 kg/cow), and milk lactose content (44.1 to 46.7 g/kg) increased linearly, whereas pasture DMI (11.2 to 8.4 kg/cow) decreased linearly with increasing concentrate feeding level. Daily CH4 production (323 to 378 g/d) increased linearly due to the increase in total DMI, whereas CH4 yield (29.1 to 25.1 g/kg of DMI) and CH4 intensity (35.5 to 21.1 g/kg of milk yield; and 28.8 to 17.6 g/kg of ECM) decreased linearly with increasing concentrate feeding level. Diurnal ruminal pH (6.45 to 6.32) and in sacco DM and neutral detergent fiber disappearance decreased linearly. Acetic and propionic acid were unaffected by treatment, whereas butyric acid (5.21 to 6.14 mM) increased linearly and quadratically with increasing concentrate feeding level. It was concluded that a high concentrate feeding level not only increases animal efficiency but is moreover a viable CH4 mitigation option for dairy cows grazing kikuyu-dominant pasture in late summer when pasture is inherently fibrous.

Effect of dietary nitrate on enteric methane emissions, production performance and rumen fermentation of dairy cows grazing kikuyu-dominant pasture during summer

Dietary nitrate supplementation is an effective methane (CH4) mitigation strategy in total mixed ration based diets fed to ruminants. To date, limited information is available on the effect of dietary nitrate on CH4 production from grazing dairy cows. Fifty-four multiparous Jersey cows were subjected to a randomised complete block design (blocked according to milk yield, days in milk and parity) to evaluate the effect of three dietary nitrate levels on enteric CH4 emissions and cow production performance. Additionally, six rumen-cannulated cows in a replicated 3 × 3 Latin square design were used in a rumen study. Dietary treatments consisted of concentrate fed at 5.4 kg of DM/cow per day containing one of three levels of dietary nitrate: 0 g (control), 11 g (low nitrate), and 23 g of nitrate/kg of dry matter (DM; high nitrate). Cows grazed late-summer pasture containing approximately 3 g of nitrate/kg of DM. Concentrates were formulated to be isonitrogenous, by substituting urea, and isoenergetic. Cows were gradually adapted to concentrates over a 3-wk period before the onset of a 57-d experimental period. Enteric CH4 emissions and total dry matter intake (DMI) from 11 cows per treatment were measured during one 6-d measurement period using the sulphur hexafluoride tracer gas technique. Individual pasture DMI was determined using TiO2 and indigestible neutral detergent fibre (NDF). Milk yield decreased by approximately 12% when feeding the high nitrate diet compared with the control and low nitrate diets. Although total DMI was unaffected by treatment, concentrate DMI decreased linearly (5.5–3.7 kg/d) while pasture DMI increased linearly (9.1–11.4 kg/d) with increasing dietary nitrate addition. Methane production (313–280 g/d), CH4 yield (21.8–18.7 g/kg of DMI) and CH4 energy per gross energy intake (6.9–5.9%) tended to decrease linearly with increasing dietary nitrate addition. Diurnal ruminal pH of the high nitrate group was greater, for selective periods after concentrate feeding, than the control and low nitrate groups. Spot sample ruminal pH (6.2–6.3) tended to increase while total volatile fatty acid (VFA) concentration (99.9–104 mM/L) increased quadratically with increasing dietary nitrate addition. Individual VFA concentrations were unaffected by treatment. Rate of NDF disappearance (2.4–2.8%/h) after 18 h of ruminal incubation tended to increase quadratically with increasing dietary nitrate addition. Dietary nitrate fed to grazing dairy cows tended to decrease CH4 emissions while improving the fibrolytic environment of the rumen. However, when feeding high levels of dietary nitrate a decrease in milk yield could be expected due to a decrease in concentrate DMI.

Effect of concentrate feeding level on methane emissions, production performance and rumen fermentation of Jersey cows grazing ryegrass pasture during spring

Dietary supplementation has been well documented as an effective enteric methane (CH4) mitigation strategy. However, limited studies have demonstrated the effect of concentrate level on enteric CH4 emissions from grazing dairy cows, and to our knowledge none of these studies included a pasture-only diet or reported on rumen fermentation measures. Sixty multiparous (4.0 ± 1.51 SD) Jersey cows, of which six were rumen-cannulated, were used in a randomised complete block design, and the cannulated cows were used in a separate replicated 3 × 3 Latin square design, to investigate the effect of concentrate supplementation (0, 4, and 8 kg/cow per day; as fed) on enteric CH4 emissions, milk production, dry matter intake (DMI), and rumen fermentation of dairy cows grazing perennial ryegrass pasture during spring, following a 14-d adaptation period. The sulphur hexafluoride tracer gas technique was used to measure enteric CH4 emissions from 10 cows of each treatment group over a single 9-d measurement period. Parallel with the CH4 measurement period, pasture DMI was determined using TiO2 and indigestible neutral detergent fibre as external and internal markers, respectively, while milk yield, milk composition, cow condition, and pasture pre- and post-grazing measurements were also recorded. Total DMI (13.4 to 18.0 kg/d), milk yield (12.9 to 19.2 kg/d), energy corrected milk (14.6 to 20.7 kg/d), milk lactose content (46.2 to 48.1 g/kg) and gross energy intake (239 to 316 MJ/d) increased, while milk fat content (50.0 to 44.2 g/kg) decreased with increasing concentrate feeding level. Volatile fatty acid concentrations and ruminal pH were mostly unaffected by treatment, while dry matter disappearance decreased and NH3-N concentration increased with increasing concentrate feeding level. Methane production (258 to 302 g/d) and CH4 yield (20.6 to 16.9 g/kg of DMI) were similar for all cows, while pasture DMI (13.4 to 10.8 kg/d) and CH4 intensity (20.4 to 15.9 g of CH4/kg of milk yield) decreased linearly with increasing concentrate feeding level. Results indicate that concentrate supplementation on high quality pasture-only diets have the potential to effectively reduce CH4 emissions per unit of milk yield from grazing cows during spring.

Supplementing Rhodobacter sphaeroides in the diet of lactating Holstein cows may naturally produce coenzyme Q10-enriched milk.

ObjectiveTo examine the effects of Rhodobacter sphaeroides (R. sphaeroides) supplementation as a direct-fed microbial (DFM) on rumen fermentation in dairy cows and on coenzyme Q10 (CoQ10) transition into milk, an in vitro rumen simulation batch culture and an in vivo dairy cow experiment were conducted.MethodsThe characteristics of in vitro ruminal fermentation were investigated using rumen fluids from six cannulated Holstein dairy cows at 2 h post-afternoon feeding. A control treatment was included in the experiments based on a typified total mixed ration (TMR) for lactating dairy cows, which was identical to the one used in the in vivo study, plus R. sphaeroides at 0.1%, 0.3%, and 0.5% TMR dry matter. The in vivo study employed six ruminally cannulated lactating Holstein cows randomly allotted to either the control TMR (C-TMR) treatment or to a diet supplemented with a 0.5% R. sphaeroides culture (S-TMR, dry matter basis) ad libitum. The presence of R. sphaeroides was verified using denaturing gradient gel electrophoresis (DGGE) applied to the bacterial samples obtained from the in vivo study. The concentration of CoQ10 in milk and in the supernatant from the in vitro study was determined using high performance liquid chromatography.ResultsThe results of the in vitro batch culture and DGGE showed that the concentration of CoQ10 significantly increased after 2 h of R. sphaeroides supplementation above 0.1%. When supplemented to the diet of lactating cows at the level of 0.5%, R. sphaeroides did not present any adverse effect on dry matter intake and milk yield. However, the concentration of CoQ10 in milk dramatically increased, with treated cows producing 70.9% more CoQ10 than control cows.ConclusionThe CoQ10 concentration in milk increased via the use of a novel DFM, and R. sphaeroides might be used for producing value-added milk and dairy products in the future.

1641 Effects of Bacillus subitilis supplementation on milk production and rumen fermentation of dairy cows

1641 Effects of Bacillus subitilis supplementation on milk production and rumen fermentation of dairy cows

Effects of addition of Aspergillus oryzae culture and 2-hydroxyl-4-(methylthio) butanoic acid on milk performance and rumen fermentation of dairy cows.

To investigate effects of Aspergillus oryzae culture (AOC) and 2-hydroxy-4-(methylthio) butanoic acid (HMB) on milk performance and rumen fermentation of dairy cows. Sixty-four multiparous Chinese Holstein cows were randomly allocated into four experimental diets: (i) Control diet; (ii) AOC diet: 5 g AOC/day per head; (iii) HMB diet: 25 g HMB/day; and (iv) AH diet: 5 g AOC plus 25 g HMB/day. Added HMB tended to increase the yield of milk protein (P = 0.06) and 3.5% fat-corrected milk (P = 0.08) and milk fat content (P = 0.09). Milk fat yield (P = 0.03) and the contents of milk protein (P = 0.05) were increased by adding HMB. The cows fed on AOC diet had a tendency for higher body weight (BW) gain (P = 0.08). Addition of AOC, HMB and AH increased content of microbial protein (MCP) and total volatile fatty acids (VFA) (P < 0.01) in rumen fluid. Populations of rumen fungi, Fibrobacter succinogenes and Ruminococcus flavefaciens relative to total bacterial 16S rDNA (P ≤ 0.03) and activity of carboxymethylcellulase (CMCase) (P < 0.01) were increased with added AOC or HMB. It is inferred that added AOC or HMB can increase the contents of MCP and total VFA potentially by stimulating rumen microbe populations and CMCase activity.

Effect of increased concentrate allotment before evening grazing on herbage intake, nitrogen utilization and rumen fermentation in dairy cows grazed on perennial ryegrass pasture.

Two experiments were conducted to elucidate the effect of increased concentrate allotment before evening grazing on herbage intake, nitrogen utilization and rumen fermentation in dairy cows. In experiment 1, nine lactating cows were grazed in the morning and evening sessions (2.5 h each). The cows were allocated to treatments of three concentrate allotment levels before the evening grazing session by altering proportions to daily total offered; 25%, 50% and 75%. Daily herbage dry matter intake quadratically decreased with increasing the concentrate allotment levels (P < 0.05). Nitrogen utilization was similar among treatments. To investigate diurnal changes in rumen fermentation, a second experiment was conducted where six ruminally cannulated non-lactating dairy cows grazed in the morning and evening sessions (3 h each) were subjected to the same treatments as experiment 1. Total volatile fatty acid concentration in the rumen linearly increased with increasing the concentrate allotment levels throughout the pre-evening grazing session to the post-morning grazing session (P < 0.01). The results indicate that dairy cows reduce daily herbage intake but do not alter nitrogen utilization with increasing concentrate allotment before evening grazing. © 2016 Japanese Society of Animal Science.

Effect of water-soluble carbohydrate content in orchardgrass pasture on grazing time and rumen fermentation in dairy cows.

Two experiments were conducted to clarify the effect of water-soluble carbohydrate (WSC) content in orchardgrass pasture on the diurnal distribution of grazing time. Six ruminally cannulated, non-lactating dairy cows were grazed on either of two pastures with different orchardgrass cultivars containing low WSC (LWSC; cultivar: 'Hokkai 28') or high WSC (HWSC; cultivar: 'Harunemidori'). The cows were grazed in morning and evening sessions in experiment 1, whereas the cows were grazed throughout the day in experiment 2. In experiment 1, grazing time of the cows on HWSC was longer than that of the cows on LWSC (P < 0.01). This difference was larger in the morning session than in the evening session (pasture × grazing session: P < 0.05). Effects on herbage intake were similar to those on grazing time. In experiment 2, daily total grazing time was longer for the cows on HWSC than for those on LWSC (P < 0.05). The cows on HWSC spent a longer time grazing than those on LWSC in the morning between 03.00 and 09.00 hours (P < 0.01). The results indicated that prolonged grazing time in the period between dawn and early morning could increase daily herbage intake in cows grazed on pastures of orchardgrass cultivars with high-WSC content.

Enteric methane production, digestibility and rumen fermentation in dairy cows fed different forages with and without rapeseed fat supplementation

The purpose of this experiment was to study the effect of forage species (grass or maize) and the maturity stage of grass on enteric methane (CH4) production, nutrient digestibility and rumen fermentation, and to study possible interactions with cracked rapeseed as fat source. Six lactating, ruminal, duodenal and ileal cannulated Holstein dairy cows (206 days in milk, milk yield 25.1kg) were submitted to an incomplete Latin square design (6×4) with six diets and four periods. Two grass silages (early first cut, 361g aNDFom/kg DM and late first cut, 515g aNDFom/kg DM) and one maize silage were supplemented with either low fat concentrate or high fat concentrate. The dietary fat concentration in the high fat diets was approximately 60g/kg DM. Diurnal samples of duodenal and ileal digesta and feces were compiled. The CH4 production was measured for four days in open-circuit respiration chambers. Additional fat reduced the gross energy (GE) lost as CH4 from 6.3 to 5.8% of GE intake, independent of forage species and quality. Energy loss as CH4 constituted 6.1, 6.7 and 5.4% of GE intake for early grass silage, late grass silage and maize silage, respectively. However, there was no difference between early grass silage and maize silage when CH4 production was related to kg organic matter (OM) digested. Fat supplementation did not affect OM or aNDFom digestibility. Maize silage had a higher ruminal OM digestibility, but lower ruminal aNDFom digestibility than grass silage. Early cut grass silage had a higher total tract OM and aNDFom digestibility than late cut grass silage. The present study demonstrates that choice of forage species and harvest time affects CH4 emission from dairy cows, while the CH4 reducing ability of fat does not interact with forage characteristics.

The effect of body condition score at calving and supplementation with Saccharomyces cerevisiae on milk production, metabolic status, and rumen fermentation of dairy cows in early lactation

The objective of this study was to examine the effects of live yeast (LY) supplementation and body condition score (BCS, 1–5 scale) at calving on milk production, metabolic status, and rumen physiology of postpartum (PP) dairy cows. Forty Holstein-Friesian dairy cows were randomly allocated to a 2 × 2 factorial design and blocked by yield, parity, BCS, and predicted calving date. Treatments were body condition at calving (low for BCS ≤3.5 or high for BCS ≥3.75; n=20) and supplementation with LY (2.5 and 10g of LY/d per cow for pre- and postcalving, respectively; control, no LY supplementation; n=20). The supplement contained 109 cfu of Saccharomyces cerevisiae/g (Yea-Sacc1026 TS, Alltech Inc., Nashville, TN). Daily milk yield, dry matter intake, milk composition, BCS, body weight, and backfat thickness were recorded. Blood samples were harvested for metabolite analysis on d 1, 5, 15, 25, and 35 PP. Liver samples were harvested by biopsy for triacylglycerol (TAG) and glycogen analysis on d 7 precalving, and on d 7 and 21 PP. Rumen fluid was sampled by rumenocentesis for all cows on d 7 and 21 PP. Supplementation with LY had no effect on milk yield, dry matter intake, rumen fluid pH, or blood metabolites concentration of dairy cows with high or low BCS at calving. Feeding LY increased rumen acetate proportion and protozoal population, tended to increase liver glycogen, and decreased rumen ammonia nitrogen during early lactation. Over-conditioned cows at calving had greater body reserve mobilization and milk production and lower feed intake, whereas cows with a moderate BCS at calving had greater feed intake, lower concentrations of nonesterified fatty acids and β-hydroxybutyrate, lower liver TAG and TAG:glycogen ratio, and faster recovery from body condition loss. Additionally, the data suggest that concentrations of liver enzymes in blood might be used as an indicator for liver TAG:glycogen ratio. Results indicate that in the case of this experiment, where the control treatment was associated with an acceptable rumen pH, feeding yeast did not significantly improve indicators of energy status in dairy cows.

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: 6mm, or longer: 19mm) 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 10.9mm and from 13.4 to 10.4mm, 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.

Effects of Chop Length of Alfalfa and Corn Silage on Milk Production and Rumen Fermentation of Dairy Cows

Effects of chop length (shorter=10mm or longer=19mm) of alfalfa silage and corn silage were determined in 16 midlactation Holstein cows using a 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 total mixed ration containing (dry matter basis) 44.0% barley grain-based energy supplement, 12.6% protein supplement, and 21.7% longer chop or shorter chop alfalfa silage and 21.7% longer chop or shorter chop corn silage. Reducing the chop length of alfalfa silage and corn silage reduced the average geometric particle length from 14.4 to 11.0mm and from 14.2 to 10.4mm, respectively. Reducing the chop length of both silages reduced the proportion of the diets retained by the 8-and 19-mm screen of the Penn State Particle Separator from 55.0 to 46.0% of dry matter. Reducing the alfalfa chop length increased total rumen volatile fatty acids at 4 to 5h after feeding but did not affect rumen pH at 4 to 5h after feeding, feed intake, and milk production. Reducing the corn silage chop length increased dry matter intake from 22.3 to 23.2kg/d, increased rumen pH at 4 to 5h after feeding from 6.12 to 6.20, but did not alter rumen volatile fatty acids at 4 to 5h after feeding or milk production. Daily milk yield, milk fat percentage, and milk protein percentage averaged 38.2kg/d, 2.62%, and 3.29%, respectively, across all diets. The low milk fat percentages suggest that all diets induced subacute ruminal acidosis (SARA), whereas the rumen pH did not indicate SARA. This discrepancy could be due to a difference in the time of rumen pH measurement and the time of the lowest rumen pH. Hence, the pH data need to be interpreted with caution. Diets could have induced SARA, because for all experimental diets the content of forage neutral detergent fiber was lower than recommended for barley grain-based diets.

Effects of grain or hay supplementation on the chewing behaviour and stability of rumen fermentation of dairy cows grazing perennial ryegrass-based pasture in spring

Cows grazing highly digestible pasture in early spring can have very low rumen fluid pH that can negatively impact on the efficiency of microbial digestion. In this experiment, cows in early lactation grazed perennial ryegrass (Lolium perenne L.)-based pasture alone at low or high allowances, or at a low allowance supplemented with either a cereal grain pellet, a chopped hay cube or a cube containing cereal grain and chopped hay to determine the effects of the addition of neutral detergent fibre as hay on chewing behaviour and stability of rumen fermentation. The hypotheses tested were that: (i) supplementing high digestibility ryegrass pasture with pelleted cereal grain would increase the proportion of the day that the pH of rumen fluid was below 6.0 and would decrease the rate of degradation of neutral detergent fibre in pasture and hay; and (ii) the inclusion of chopped hay with the cereal grain supplement in cubes would reduce the proportion of the day that the rumen fluid pH was below 6.0 and restore the rate of degradation of neutral detergent fibre in pasture and hay to that in unsupplemented cows. Rumen fluid pH was highest (P&lt;0.05) in cows fed a chopped hay cube and lowest (P&lt;0.05) in cows fed a cube containing cereal grain and chopped hay, with no significant (P&gt;0.05) difference between those fed pasture only or cereal grain pellets. The introduction of grain, with or without hay, did not substantially alter the pattern or magnitude of changes in rumen fluid pH, but did reduce (P&lt;0.05) the rate of degradation of neutral detergent fibre in pasture (5.3 v. 7.6%/h) and hay (2.7 v. 5.0%/h) in the rumen. Rumen degradation rates of pasture dry matter and neutral detergent fibre were not improved by adding chopped hay. Total volatile fatty acid concentrations in rumen fluid were highest (P&lt;0.05) on the high pasture allowance treatment and lowest (P&lt;0.05) on the low pasture allowance and the chopped hay cube treatments. Supplementation with grain reduced (P&lt;0.05) the proportion of acetate and increased (P&lt;0.05) the proportion of propionate in total volatile fatty acids. There were no significant (P&gt;0.05) effects of dietary treatment on time spent grazing or on rate of biting while grazing. Cows in treatments receiving grain supplements (532 min) and those in the high pasture allowance treatment (566 min) spent more (P&lt;0.05) time ruminating than those in the low pasture allowance (415 min) and chopped hay cube (465 min) treatments. The relative contributions of low pH and of starch to the reduction in rates of dry matter and neutral detergent fibre degradation in the rumen cannot be determined from this experiment, however, it is likely that both factors contribute to a relative increase in the metabolic activity of non-cellulolytic microorganisms.

Effects of wilted grass silages varying in fermentation quality on rumen fermentation of dairy cows

Effects of wilted grass silages varying in fermentation quality on rumen fermentation of dairy cows

Effect of silage type and supplementation with sucrose or lactic acid on rumen fermentation in dairy cows

Recent studies have shown increased silage intake and improved milk fat concentration in dairy cows offered restricted compared to extensively fermented silages (Chamberlain et al., 1990; Mayne 1992). Changes in milk composition may be related to increased intake per se and/or alterations in rumen fermentation parameters. A study was therefore undertaken to examine the effects of silage fermentation type, dry matter intake and the addition of water soluble carbohydrate (WSC) or lactic acid on rumen fermentation parameters in dairy cows.Two direct cut grass silages were prepared using either an inoculant (Ecosyl, 3 1/t, ICI. pic) or Maxgrass (BP Chemicals, 6 1/t). Five silage only treatments were offered to four ruminally fistulated dairy cows in a five period, partially balanced, changeover design experiment. Each period was of 4 weeks duration. Treatment 1: Inoculant treated silage (I), 2: Maxgrass silage (M), 3: Maxgrass ad-libitum (MAL), 4: Inoculant + sucrose (500 g/day) (IS), 5: Maxgrass + lactic acid (200 ml/day) (ML).

The effect of daily administration of recombinantly‐derived somatotropic hormone on feed intake, digestibility, milk composition and rumen fermentation in dairy cows1

ZusammenfassungDer Effekt täglicher Injektionen von rekombinantem bovinem Wachstumshormon auf Futteraufnahme, Verdaulichkeit, Milchzusammensetzung und Verdauungsablauf im Pansen von MilchkühenDer Effekt von rekombinantem bovinem Wachstumshormon (rbSTH) auf Futteraufnahme, Verdaulichkeit, Milchzusammensetzung und den Verdauungsablauf wurde an vier Milchkühen mit Pansenfisteln untersucht. Der Versuch umfaßte sieben Perioden von je 21 Tagen. Die Messungen wurden zwischen dem 15. und 21. Tag durchgeführt. In zwei Perioden (42 Tagen) wurde den Tieren täglich rbSTH injiziert. Der Einfluß von rbSTH wurde für jede Kuh und Periode als Differenz zwischen den festgestellten Werten und Kontrollwerten ermittelt. Diese errechneten sich aus Meßperioden vor und nach der Behandlung mit rbSTH. In der ersten Periode der rbSTH‐Applikation war die festgestellte Futteraufnahme niedriger als die geschätzten Kontrollwerte und die Verdaulichkeit der organischen Substanz und der Zellwände reduziert. Der Anteil von langkettigen Fettsäuren (C16:0 bis C20:4) im Milchfett war negativ korreliert mit der Netto‐Energiebilanz (r = ‐0,69). Die Mittelwerte von flüchtigen Fettsäuren und Ammoniak waren in der ersten rbSTH‐Periode leicht reduziert. In dieser Periode waren der Gehalt an Organischer Substanz und Zellwandbestandteilen im Pansen reduziert. Die Applikation von rbSTH erhöhte die berechnete Resorption von flüchtigen Fettsäuren.

Influence of declining level of feed intake and varying the proportion of starch in the concentrate on rumen fermentation in dairy cows

Five dairy cows fitted with large rumen cannulae were fed diets of 2 3 pelleted concentrate containing five graded levels of starch between 8 and 32%. Intake declined at five equal intervals from 19.4 kg organic matter per day in early lactation to 4.9 kg in the dry period before parturition. Measurements were made on average values and range during the day for pH and concentrations of ammonia (NH 3), D,L-lactic acid (HL), total volatile fatty acids (t-VFA), acetic acid (HAc), propionic acid (HP), butyric acid (HB), and the minor VFAs valeric (HV), caproic (HC), isobutyric (IHB), 2-methylbutyric (2MHB) and 3-methylbutyric (3MHB). Decreased level of intake significantly ( P<0.05) increased average pH (from 6.0 at the highest to 6.6 at the lowest level of intake) and decreased average concentrations of HL and of t-VFA (from 131 to 93 mmol L −1). Of the minor VFAs only HV and HC significantly decreased. Range during the day was decreased for pH (from 1.07 to 0.5) and for the concentrations of NH 3, HL, t-VFA (from 61 to 35 mmol L −1), HV and HC. Decreasing the level of starch significantly ( P<0.05) decreased concentrations of HP, HV, IHB, and 3MHB. Range during the day was decreased for pH and HB and increased for the concentrations of 2MHB and 3MHB. It is concluded that changes in level of feed intake are quantitatively more important in rumen fermentation than increasing levels of starch in the concentrate.