Rumen Neutral Detergent Fiber Research Articles

Effect of supplemental yeast culture and dietary starch content on rumen fermentation and digestion in dairy cows

The objectives of this experiment were to evaluate the effect of feeding a culture of Saccharomyces cerevisiae on rumen metabolism and digestibility when cows are fed diets varying in starch content. Four lactating Holstein cows were assigned to a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Treatments were low starch (LS; 23% of diet DM) and no yeast culture (YC; LS-control), LS and 15 g of YC/d (LS-YC), high starch (HS; 29% of diet DM) and no YC (HS-control), and HS and 15 g of YC/d (HS-YC). Periods lasted 28 d, with the last 9 d for data collection. Days 20 to 24 were used to determine production, nutrient flow, and digestibility. On d 25, 3 kg of corn grain DM was placed in the rumen 1 h before the morning feeding, and yields of milk and milk components were measured after the challenge. Blood was sampled -1, 3, 7, and 11 h relative to the morning feeding on d 24 and 25. Rumen pH was measured continuously on d 24 and 25. Rumen papillae were collected on d 24 and 28 to quantify mRNA expression of select genes. Supplementing YC increased yields of milk (26.3 vs. 29.6 kg/d), energy-corrected milk (ECM; 26.5 vs. 30.3 kg/d), fat (0.94 vs. 1.08 kg/d), true protein (0.84 vs. 0.96 kg/d), and ECM/dry matter intake (1.15 vs. 1.30) compared with the control but did not affect dry matter intake (22.6 vs. 22.9 kg/d). Cows fed HS had increased milk true protein percentage (3.18 vs. 3.31%) and yield (0.87 vs. 0.94 kg/d) compared with cows fed LS. Feeding HS-YC increased the proportion of dietary N incorporated into milk true protein from 24.9% in the other 3 treatments to 29.6%. Feeding HS increased the concentration of propionate (21.7 vs. 32.3 mM) and reduced that of NH3-N (8.3 vs. 6.7 mg/dL) in rumen fluid compared with the control, and combining HS with YC in HS-YC tended to increase microbial N synthesis compared with LS-YC (275 vs. 322 g/d). Supplementing YC to cows fed HS reduced plasma haptoglobin and rumen lactate concentrations, increased mean rumen pH, reduced the time with pH <6.0, and prevented the decrease in rumen neutral detergent fiber digestion caused by HS. Cows fed HS had less total-tract digestion of organic matter (73.9 vs. 72.4%) because of reduced acid detergent fiber (57.6 vs. 51.7%) and neutral detergent fiber (60.9 vs. 56.7%) digestibility. Production performance after the challenge was similar to that before the challenge, and YC improved yield of ECM. After the challenge, supplementing YC tended to reduce rumen lactate concentration compared with the control and reduced haptoglobin in cows fed HS. Feeding HS but not YC increased expression in rumen papillae of genes for receptors (FFAR2 and FFAR3) and transporter (SLC16A3) of short-chain fatty acids but did not affect genes involved in transport of Na+/H+ or water or in inflammatory response. Supplementing YC to dairy cows improved lactation performance in diets containing low or high starch, and mechanisms might be partially attributed to improvements in rumen pH, digestion of fiber, microbial N synthesis, and reduction in acute phase response.

The effects on digestibility and ruminal measures of chemically treated corn stover as a partial replacement for grain in dairy diets

Alkaline treatment of gramineous crop residues can convert an abundant, minimally utilized, poorly digestible straw into a moderately digestible feedstuff. Given the volatile nature of grain prices, substitution of treated stover for grain was investigated with dairy cows to provide insights on ruminal and digestibility effects of a feed option that makes use of alternative, available resources. The objective of this study was to evaluate changes in diet digestibility and ruminal effects when increasing levels of calcium oxide-treated corn stover (CaOSt) were substituted for corn grain in diets of lactating cows. Mature corn stover was treated with calcium oxide at a level of 50g∙kg−1 dry matter (DM), brought up to a moisture content of 50% following bale grinding, and stored anaerobically at ambient temperatures for greater than 60d before the feeding experiment. Eight ruminally cannulated Holstein cows averaging 686kg of body weight and 35kg of milk∙d−1 were enrolled in a replicated 4×4 Latin square, where CaOSt replaced corn grain on a DM basis in the ration at rates of 0, 40, 80, and 120g∙kg−1 DM. All reported significant responses were linear. The DM intake declined by approximately 1kg per 4% increase in CaOSt inclusion. With increasing replacement of corn grain, dietary neutral detergent fiber (NDF) concentration increased. However, rumen NDF turnover, NDF digestibility, NDF passage rate, and digestion rate of potentially digestible NDF were unaffected by increasing CaOSt inclusion. Total-tract organic matter digestibility declined by 5 percentage units over the range of treatments, approximately 1.5 units per 4-percentage-unit substitution of CaOSt for grain. With increasing CaOSt, the molar proportions of butyrate and valerate declined, whereas the lowest detected ruminal pH increased from 5.83 to 5.94. Milk, fat, and protein yields declined as CaOSt increased and DM intake declined with the result that net energy in milk declined by approximately 1 Mcal per 4% increase in CaOSt. Time spent ruminating (min∙kg−1 DM intake) increased with increasing CaOSt, though total minutes per day were unaffected. These insights on the effect of substitution of treated corn stover for corn grain may be used to predict the effect on nutrient supply to the cow over a range of substitution levels. The acceptability of the effect will depend on the economics of milk production and availabilities of feedstuffs.

Rumen function in vivo and in vitro in sheep fed Leucaena leucocephala.

The effect of Leucaena leucocephala inclusion in sheep diets upon rumen function was evaluated. Nine Pelibuey sheep, 32.6 ± 5.33kg live weight (LW), fitted with rumen cannula were used. A complete randomized block design was employed. Two experimental periods of 60days each, with 60-day intervals between them, were used. Experimental treatments were as follows (n = 6): T1 (control), 100% Pennisetum purpureum grass; T2, 20% L. leucocephala + 80% P. purpureum; T3, 40% L. leucocephala + 60% P. purpureum. In situ rumen neutral detergent fiber (aNDF) and crude protein (CP) degradation, dry matter intake (DMI), volatile fatty acids (VFA) production, estimated methane (CH4) yield, rumen pH, ammonia nitrogen (N-NH3), and protozoa counts were measured. The aNDF in situ rumen degradation of P. purpureum and leucaena was higher (P < 0.05) in T2 and T3. Leucaena CP degradation was higher in T2 and T3 but for P. purpureum it was only significantly higher in T3. Leucaena aNDF and CP degradation rate (c) was 50% higher (P < 0.05) in T2 and T3, but only higher in T3 for P. purpureum. Voluntary intake and rumen (N-NH3) was higher in T2 and T3 (P = 0.0001, P = 0.005, respectively). Molar VFA proportions were similar for all treatments (P > 0.05). Protozoa counts and in vitro gas production (48h) were lower in T2 and T3 (P < 0.05, P < 0.0001). Estimated methane yield (mol CH4/day) was higher in sheep fed leucaena (P < 0.0001). However, CH4 yield relative to animal performance (mol CH4/g LW gain) was lower in T2 and T3 (P < 0.0001). In summary, these results indicate that including L. leucocephala in sheep diets did not modify rumen fermentation pattern (same VFA ratios) nor reduce the amount of CH4 per unit of DMI (mol CH4/g DMI). However, leucaena inclusion does increase rumen N-NH3, aNDF and CP digestibility, and voluntary intake.

Studies on Brassica carinata Seed. 2. Carbohydrate Molecular Structure in Relation to Carbohydrate Chemical Profile, Energy Values, and Biodegradation Characteristics

The objectives of this study were to investigate (1) the carbohydrate chemical profile, (2) the energy values, (3) the rumen neutral detergent fiber (NDF) degradation kinetics, (4) the carbohydrate-related functional group structural features using a Fourier transform infrared (FTIR) spectroscopic technique with attenuated total reflectance (ATR), and (5) the correlations between carbohydrate intrinsic structural features and nutritional profiles in three strains of Brassica carinata in yellow and brown seed coats, with comparison to canola seed as a reference. The results showed that yellow B. carinata strains 111000EM and AAC A100 were lower for contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and carbohydrate (CHO) and higher for contents of total digestible nutrients (TDN), energy values, and effective degradable NDF (EDNDF) than brown-seeded 110915EM. In comparison, brown canola seed (Brassica napus L.) had more fiber content and less EDNDF. Also, carinata strains showed significantly different IR intensities in structural carbohydrate (SCHO), cellulosic compounds (CELC), and total CHO profiles. These structural variations might be one of the possible reasons for various fiber profile and biodegradation characteristics for ruminants in oilseeds. However, multivariate analyses within carbohydrate regions indicated there were still some structural relationships among the four oilseed samples. Moreover, the correlation study showed that the changes of CELC and CHO peak intensities were highly related with some changes in CHO chemical profile, energy values, and in situ NDF degradation kinetics in B. carinata and canola seeds. Further study with a large sample size is still necessary to figure out whether CHO molecular spectral information could be used to predict nutrient values and biological behavior in oilseeds.

Parameterization of ruminal fibre degradation in low-quality tropical forage using Michaelis–Menten kinetics

This work aimed to parameterize the ruminal degradation of neutral detergent fibre (NDF) from low-quality tropical forage using Michaelis–Menten kinetics. The intake, rumen outflow ( L), fractional degradation rate (kd), discrete lag (LAG) and effective degradability (ED) of NDF, and the microbial flow of nitrogenous compounds into the small intestine (Nmic) were assessed in two 5 × 5 Latin square experiments by using five Holstein × Zebu heifers cannulated in the rumen. The experiments were carried out sequentially and the treatments were formed by increasing the level of supplementation with nitrogenous compounds. A low-quality signal grass ( Brachiaria decumbens) hay was used as roughage. The nitrogen supplement was a mixture of urea, ammonium sulfate and albumin, at the ratios of 4.5:0.5:1.0, respectively. The crude protein contents in the diets ranged from 51.9 to 136.3 g/kg of dry matter. The rumen ammonia nitrogen (RAN) concentration was used as an independent variable. The NDF intake, L and Nmic showed a quadratic pattern ( P < 0.05) as a function of RAN concentration, and the critical points (maximum responses) were observed with 15.17, 16.28, and 14.52 mg of RAN/dL of rumen fluid, respectively. On the other hand, ED and LAG presented a linear-response-plateau ( P < 0.05) according to the RAN concentration, with break points close to 8 mg/dL for ED (maximum estimate) and LAG (minimum estimate). The RAN concentrations to optimize NDF degradation and intake were defined as 8 and 15 mg/dL, respectively. This difference between estimates appears to be due to a better adequacy of the metabolizable protein:metabolizable energy ratio in the animal metabolism, which increases the animal intake even after the rumen NDF degradation has been optimized. This observation was supported by Nmic pattern. An adapted Michaelis–Menten model was applied to the data, where RAN was the independent variable and kd the dependent variable. The relationship between these variables was found to be significant by using the Hanes–Woolf plot ( P < 0.01). Based on this model, the rate of NDF degradation as a function of RAN concentration indicates that fibre degradation in the rumen could be considered a second order process. In this context, the RAN concentration of 8 mg/dL was assumed as the limit where zero order (below limit) and first order (above limit) reactions become predominant for NDF degradation in the rumen.

Cell wall digestion and passage kinetics estimated by marker and in situ methods or by rumen evacuations in cattle fed hay 2 or 18 times daily

This study was conducted to determine the effects of timing rumen evacuations on kinetic parameter estimates of wall digestion and passage. Another objective was to estimate the rate constants of rumen neutral detergent fibre (NDF) kinetics in cattle fed grass hay using rumen evacuations, and to compare the results to those obtained by conventional methods ( in situ incubation, marker kinetics). Four young cattle were used in a switch-back design and fed a grass hay diet either twice daily at 7.00 and 19.00 h or 18 times per day starting at 7.00 h. Rumen evacuations were made just before morning feeding (7.00 h) and 11.00 and 15.00 h. The ingested feed, rumen and duodenal digesta and faeces were divided into five particle size fractions by wet sieving. Particulate matter retained on the sieves were analysed for NDF which was further subdivided into digestible (DNDF) and indigestible NDF (INDF) by 12-day in situ incubation. The rate constants were derived from average rumen pool sizes by pooling the particle fractions into large, medium and small particles (three-pool) or into large and small particles (two-pool). Feeding frequency had no effect on ruminal or total digestibility, average rumen pool size or kinetic parameters. The results showed that kinetic parameters, estimated from a single evacuation, can be severely biased due to under- or overestimation of rumen pool size. The rate of particle breakdown based on rumen INDF kinetics was slower than the passage rate of small particles (0.033 h −1 versus 0.047 h −1). Digestion rate of medium particles was faster than that of large or small particles. The passage rate of both DNDF and INDF increased with decreasing particle size and it was slower for DNDF than for INDF irrespective of particle size indicating selective retention. Digestion rate of DNDF estimated by the in situ incubation was lower than that derived from rumen evacuation. Model calculations suggested that the values based on the in situ incubations were underestimated. Ytterbium labelled hay underestimated the residence time in ruminal compartments compared with INDF estimated by rumen evacuation technique (42.5 h versus 49.8 h). However, the passage rates of small particles estimated from the marker kinetics were similar to those derived from rumen evacuation.

Use of animal and dietary information to predict rumen turnover

A database was developed from 16 scientific publications to explore mechanisms controlling rumen turnover. The database included 70 treatment means (43 cattle and 27 sheep) from experiments in which rumen contents were measured by complete manual evacuation or by slaughter. Rumen turnover was estimated as the ratio between rumen contents (kg of DM) and feed intake (kg of DM/h). Predictors were intake, body weight (BW), metabolic BW (BW 0.75), and the dietary components crude protein (CP), neutral detergent fiber (NDF), neutral detergent solubles (NDS), acid detergent lignin and ash. The best linear models obtained to predict rumen turnover ( T) for NDF, NDS, dry matter (DM) and acid detergent lignin (LIGN), respectively, were: T NDF =23.84−10.26 ln( D- NDFI); r 2:0.28,P<0.001 T NDS =17.08−13.39 ln( D- NDSI); r 2:0.76,P<0.001 T DM =20.16−10.14 ln( D- NDSI); r 2:0.65,P<0.001 T LIGN =37.69−30.77 ln( D- NDFI); r 2:0.70,P<0.001 These curvilinear relationships were likely due, at least for NDF and lignin, to the increase in rumen NDF content (% of BW) that occurred when intake of dietary, or forage, NDF (% of BW) increased. In the database, turnover of NDF and NDS showed additive behavior. No differences were found between cattle and sheep in rumen NDF, NDS and DM turnovers. When fed at the same level of intake of forage NDF (% of BW), sheep had significantly lower rumen NDF contents (% of BW) than cattle. The rumen evacuation technique is a valuable tool to explore interspecies relationships. The use of this large dataset derived from the scientific literature improved the understanding of the relationships existing among feed intake, body size and the components of rumen turnover, and allowed their quantification.

Effect of Casein Infusion in the Rumen, Duodenum or Both Sites on Factors Affecting Forage Intake and Performance of Dairy Cows Fed Red Clover-Grass Silage

Four lactating dairy cows were used in a balanced 4 × 4 Latin square design to examine the effects of casein infusion in the rumen, duodenum, or both on the intake of red clover-grass silage, chewing behavior, diet digestion, microbial protein synthesis, rumen fermentation, digestion, and passage kinetics, milk production, and milk composition. Duodenal infusion increased eating time, silage intake, rumen neutral detergent fiber pool, yields of milk, protein, and lactose, and concentration of milk protein, and tended to decrease that of milk fat. Ruminal infusion tended to decrease eating time, and increased significantly microbial protein synthesis, rumen ammonia-N concentration, molar proportions of isovalerate and valerate, digestion rate of digestible neutral detergent fiber, passage rate of indigestible neutral detergent fiber, and milk urea content, and decreased rumen neutral detergent fiber pool. Silage intake, and yields of milk, protein, and lactose were highest when casein was simultaneously infused in both sites.

Nitrogen and fiber concentration in rumen contents and feces contents of Mongolian gazelles

Fecal indicators of nutritional status of wild ungulates were less constrained than that of blood, rumen contents, or urine analyses. Thus, we compared the nitrogen and fiber concentrations of feces with those of the rumen contents of Mongolian gazelles (Procapra guttrurosa) in Hulunbeier Grassland. Rumen contents and fecal nutritional concentrations varied in different seasons. Dietary nitrogen concentrations only increased linearly with increase nitrogen concentration in fecal in winter. There was a positive correlation between rumen NDF (neutral detergent fiber) and fecal NDF concentrations. But the regression coefficient was small (r=0.3917). There was a significant regression equation between rumen contents ADF (acid detergent fiber) and fecal ADF concentrations, as well as ADL (acid detergent lignin) concentrations. Nitrogen concentration was found to be negatively correlated with NDF, ADF, and ADL concentrations both in rumen and in fecal compositions. Our data suggest that fecal nitrogen, ADF, ADL concentrations may assess winter dietary qualities that are in protein, crude fiber and lignin concentrations for Mongolian gazelles.

Influence of degradability of supplemental protein and time post-partum in early lactation dairy cows. 2. Kinetics of rumen ingesta turnover and whole tract digestibility

Eight lactating dairy cows with rumen cannulae were fed either high or low concentrate totally mixed diets in two blocks of four cows. The forage source was a low quality (9.1% crude protein, 61% neutral detergent (ND) fibre) whole crop oat silage. Degradability of supplemental protein was varied within each block by substituting corn gluten meal, a slowly fermented protein, for canola meal, a rapidly fermented protein. Measurements were made in early lactation (weeks 4 to 13 inclusive) to determine effects of diet concentrate level, degradability of supplemental protein, and time opost-partum on whole tract digestibility, rumen organic matter (OM) and nitrogen (N) pool sizes, and rates of rumen ND fiber passage. Whole tract digestibility of dry matter (DM) and OM was higher for cows fed high concentrate diets, reflecting the higher dietary inclusion of starch, Rumen ND fibre and bacterial OM pool sizes did not differ between dietary concentrate levels. Total non-ammonia N (NAN) pool was higher for cows fed high concentrate diets and this was primarily non-bacterial N, as bacterial N as a proportion of total rumen NAN was higher for cows fed low concentrate diets. Rumen OM and NAN pool sizes were little influenced by dietary protein degradability or time post-partum, although pool sizes of most components tended to increase as time post-partum increased. Rate of rumen ND fibre digestion was lower for low concentrate fed cows. Rate of rumen passage of ND fibre and liquids decreased with increasing time post-partum for low concentrate fed cows.

Influence of declining level of feed intake and varying the proportion of starch in the concentrate on rumen ingesta quantity, composition and kinetics of ingesta turnover in dairy cows

Five dairy cows fitted with large-diameter rumen cannulae were fed diets of two-thirds pelleted concentrate that contained 5 proportions of starch (8, 14, 20, 26 or 32%). Measurements were made over one complete lactation to determine the effects of intake level and proportion of starch in the concentrate on rumen content of soluble and dry matter (DM) components as well as the kinetics of rumen neutral detergent (ND) fibre digestion and passage. Intake declined from 19.44 to 4.86 kg organic matter (OM) per day at equal intervals. Rumen content of total ingesta, non-DM ingesta and all measured components of DM ingesta declined ( P <0.05) as level of intake declined, although the form of the reductions differed. Rumen pool sizes of ammonia and all volatile fatty acids (VFA's) either did ( P <0.05), or tended to ( P <0.10), decline as level of intake declined. Rumen passage rate of ND fibre declined linearly ( P <0.05), but tended ( P <0.10) to decline at an increasing rate as level of intake declined. Rumen rate of ND fibre digestion increased linearly ( P <0.05), but tended ( P <0.10) to increase at a decreasing rate as intake level declined. Rate of digestion of ND fibre in the rumen was closely related to rumen pH and rumen bacterial OM (RBOM) as a proportion of rumen ND fibre (RNDF); rate of digestion of ND fibre increasing as pH and RBOM/RNDF increased.