Ruminal NDF Research Articles

Ruminal passage rate and digestibility of fiber from dairy cows consuming diets containing alfalfa and orchardgrass hays with different concentrations of undegradable neutral detergent fiber (uNDF)

This study aimed to evaluate the effect of feeding diets with different fractions of undegraded NDF (uNDF) and potentially degradable (pdNDF) on ruminal NDF degradation and passage kinetics of lactating dairy cows. Six rumen-cannulated (533 ± 43 kg BW and 122 ± 15 DIM) and 6 non-cannulated (558 ± 62 kg BW and 126 ± 16 DIM) primiparous Holstein dairy cows were randomly assigned to 1 of 2 experimental diets in a crossover design with 2 28-d periods. The experimental diets were formulated to include either alfalfa hay (ALFA) or orchardgrass hay (ORCH) in addition to corn silage. Rations were formulated to contain 30% NDF (DM basis), where the concentrate, corn silage, and each of the hays provided one third of the dietary NDF. The marker dilution technique was used to measure the passage rate utilizing a pulse dose of marked corn silage fiber. On d 17 and 24 of each period, ruminal contents were evacuated to determine ruminal pool size. Following the return of the ruminal contents containing the pulse dose of marked corn silage to the rumen, ruminal grab samples were collected at 0, 3, 6, 9, 12, 24, 36, 48, 60, and 72 h. Samples from each time point were separated into solids and liquid, and the solids were analyzed for NDF, uNDF, and marker concentration. Alfalfa hay had a higher concentration of CP (16.4 vs. 10.7%) and a lower concentration of NDF (38.0 vs. 63.2) than orchardgrass hay. Alfalfa hay had a greater concentration of uNDF than orchardgrass hay (36.5 vs. 32.8% uNDF; NDF basis). Cows consuming the ALFA diet had similar milk yield (39.1 kg/d) and similar milk fat and protein concentrations (3.72% fat and 3.24% protein, respectively) than cows consuming the ORCH diet. Cows consuming the ALFA diet consumed more DM (26.7 vs. 24.6 kg/d) and uNDF (2.7 vs. 2.3 kg/d), than cows consuming the ORCH diet. Cows consuming the ALFA diet digested more NDF and pdNDF than cows consuming the ORCH diet (3.3 vs. 2.8 kg/d). Even though cows consuming the ALFA diet had a smaller pool size of NDF than cows consuming the ORCH diet (5.4 vs. 6.7 kg), the pool size of uNDF did not differ between groups (2.4 kg). Cows consuming the ALFA diet had a faster rate of passage of uNDF than cows consuming the ORCH diet (5.02 vs. 4.03%/h). This translated into a shorter mean retention time of uNDF for cows consuming the ALFA diet relative to cows consuming the ORCH diet (21.0 vs. 26.2 h). In conclusion, cows consuming diets containing alfalfa hay had a faster ruminal passage rate and a shorter mean retention time of uNDF than cows consuming diets containing orchardgrass hay, and this occurred despite the greater concentrations of dietary uNDF in the alfalfa-based diet. These findings suggest that the kinetics of ruminal digestion and passage influence NDF degradation in ways beyond uNDF concentration or forage quality.

Effects of bacterial direct-fed microbial mixtures offered to beef cattle consuming finishing diets on intake, nutrient digestibility, feeding behavior, and ruminal kinetics/fermentation profile.

Effects of bacterial direct-fed microbial (DFM) mixtures on intake, nutrient digestibility, feeding behavior, ruminal fermentation profile, and ruminal degradation kinetics of beef steers were evaluated. Crossbred Angus ruminally cannulated steers (n = 6; body weight [BW] = 520 ± 30kg) were used in a duplicated 3 × 3 Latin square design and offered a steam-flaked corn-based finisher diet to ad libitum intake for 3, 28-d periods. Treatments were 1) Control (no DFM, lactose carrier only); 2) Treat-A (Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus subtilis, and Bacillus licheniformis), at 1:1:1:3 ratio, respectively; totaling 6 × 109 CFU (50mg)/animal-daily minimum; and 3) Treat-B, the same DFM combination, but doses at 1:1:3:1 ratio. Bacterial counts were ~30% greater than the minimum expected. Data were analyzed using the GLIMMIX procedure of SAS with the model including the fixed effect of treatment and the random effects of square, period, and animal (square). For repeated measure variables, the fixed effects of treatment, time, and their interaction, and the random effects of square, period, animal (square), and animal (treatment) were used. Preplanned contrasts comparing Control × Treat-A or Treat-B were performed. Intake and major feeding behavior variables were not affected (P ≥ 0.17) by treatments. Steers offered Treat-A had an increased (P = 0.04) ADF digestibility compared with Control. Steers offered Treat-A experienced daily 300min less (P = 0.04) time under ruminal pH 5.6, a greater (P = 0.04) ruminal pH average and NH3-N concentration (P = 0.05) and tended (P = 0.06) to have a lower ruminal temperature compared to Control. Ruminal VFA was not affected (P ≥ 0.38) by treatments. Steers offered Treat-A increased (P = 0.02) and tended (P = 0.08) to increase the ruminal effective degradable NDF and ADF fractions of the diet-substrate, respectively. When the forage-substrate (low quality) was incubated, steers offered Treat-A tended (P = 0.09) to increase the effective degradable hemicellulose fraction compared to Control. In this experiment, the bacterial combinations did not affect intake and feeding behavior, while the combination with a greater proportion of B. licheniformis (Treat-A) elicited an improved core-fiber digestibility and a healthier ruminal pH pattern, in which the ruminal environment showed to be more prone to induce the effective degradability of fiber fractions, while also releasing more NH3-N.

153 Phenotypic Selection of Efficient Beef Cows and Differences in Digestive Physiology

Abstract This study evaluated beef cows identified as having high or low efficiency when managed in extensive systems and whether they differ in terms of digestive physiology. Nine high (HE) and low efficiency (LE) cows were selected from a group of 86 Angus cows using 2 years of selection data. Yearly ranks were assessed based on three weighted criteria: cow rump fat at calving; calving interval; and calf weaning weight. The 18 cows were then ruminally cannulated and used to evaluate their response to high (HQ; 41.0±0.78% NDF), medium-high (MHQ; 56.9±1.17% NDF), moderate (MQ; 62.5±3.40% NDF), and low-quality forage (LQ; 64.3±1.40% NDF) diets using four consecutive 26-d periods where diet quality progressively decreased by period for all cows. There was no phenotype′diet interactions. Start and end BW were 48 and 45 kg less (P< 0.01) and rump fat was thicker for HE than LE cows (P=0.02). Although total DMI did not differ (13.0 kg/d; P=0.93), DMI (%BW) was greater for HE (2.12%) than LE (1.97%, P< 0.01). Ruminal pH, short-chain fatty acid concentration, and the molar proportion of acetate, butyrate, and propionate did not differ. Ruminal digesta weight was 4 kg greater (P=0.04) and the pool sizes of DM (P=0.01), NDF (P=0.03) and undigested NDF (P< 0.01) were greater for LE than HE. Ruminal NDF passage rate was greater for HE than LE cows (3.11 vs. 2.89%/h, P=0.05), but there were no differences for the rate of NDF digestion. Ruminal contraction amplitude (P=0.01) and peak area (P< 0.01) were higher for LE than HE cows. Apparent total tract nutrient digestibility did not differ (P≥0.23). Cows identified as being efficient under an extensive management system have greater DMI as a proportion of BW, less ruminal digesta weight, and greater NDF passage rate but did not differ for total tract digestibility.

Improvement of Ruminal Neutral Detergent Fiber Degradability by Obtaining and Using Exogenous Fibrolytic Enzymes from White-Rot Fungi.

Simple SummaryNeutral detergent fiber (NDF) quantifies the primary cell wall contents in ruminant feedstuff, and its degradability is related to intake and the quality of milk and meat production in ruminants. Overall, cellulases and xylanases, considered as endogenous fibrolytic enzymes (EFEs), can be obtained from white-rot fungi and utilized to increase ruminal NDF degradability. Although EFE can improve the NDF degradability and, therefore, animal productivity, results can be inconsistent. However, considering the ratio of cellulases to xylanases during the effect of EFEs on animal productive behavior has allowed us to find consistent correlations among previously published studies. The culture media where EFEs are obtained, in addition to the biotechnical tools—such as enzymatic activity analysis, metagenomics, metatranscriptomics, and enzyme immobilization—allow researchers to obtain or design products specific to ruminant feed applications.The present review examines the factors and variables that should be considered to obtain, design, and evaluate EFEs that might enhance ruminal NDF degradability. Different combinations of words were introduced in Google Scholar, then scientific articles were examined and included if the reported factors and variables addressed the objective of this review. One-hundred-and-sixteen articles were included. The fungal strains and culture media used to grow white-rot fungi induced the production of specific isoforms of cellulases and xylanases; therefore, EFE products for ruminant feed applications should be obtained in cultures that include the high-fibrous forages used in the diets of those animals. Additionally, the temperature, pH, osmolarity conditions, and EFE synergisms and interactions with ruminal microbiota and endogenous fibrolytic enzymes should be considered. More consistent results have been observed in studies that correlate the cellulase-to-xylanase ratio with ruminant productive behavior. EFE protection (immobilization) allows researchers to obtain enzymatic products that may act under ruminal pH and temperature conditions. It is possible to generate multi-enzyme cocktails that act at different times, re-associate enzymes, and simulate natural protective structures such as cellulosomes. Some EFEs could consistently improve ruminal NDF degradability if we consider fungal cultures and ruminal environmental conditions variables, and include biotechnological tools that might be useful to design novel enzymatic products.

Effects of mixing Stylosanthes conserved as hay or silage with corn silage in diets for feedlot beef cattle

The objective of this study was to evaluate the total and partial digestibility, ruminal pH and ammonia nitrogen (NH3-N) concentration, nitrogen balance (Experiment 1) and performance (Experiment 2) of beef cattle fed diets containing corn silage (CS) and Stylosanthes (silage or hay) as forage source. Treatments were: 1) CS; 2) Stylosanthes silage (StS); 3) Stylosanthes hay (StH); 4) CS + StS (StS-mixed diet); and 5) CS + StH (StH-mixed diet). Experimental diets (125 g CP/kg DM) consisted of 50% forage and 50% concentrate (DM basis). Five cannulated bulls (251 ± 42.6 kg of body weight) were distributed to a 5 × 5 Latin square (Experiment 1). The trial lasted 80 d. The experiment 2 was performed with 40 bulls (360 ± 2.7 kg of body weight) in a completely randomized design and eight replicates during a 99-days period. In experiment 1, CS diet showed greater (P ≤ 0.02) total digestibility of DM, OM, CP and NDF than other diets. Mixed diets had greater (P = 0.02) total NDF digestibility compared to StS and StH. Corn silage showed greater total digestibility of DM, OM, NDF and CP (P ≤ 0.03) compared to mixed diets. Ruminal NDF digestibility was greater (P = 0.03) for CS than other diets. Ruminal pH was greater (P < 0.01) for StS and StH compared to mixed diets. There was a treatment × hour interaction (P = 0.02) for ruminal NH3-N. In the experiment 2, animals fed CS presented lower (P ≤ 0.03) intake of DM, OM, EE, NDF, iNDF, but greater (P ≤ 0.01) intake of TDN, DOM and NFC than animals fed other diets. The intake of all nutrients, except for NDFi, was greater for mixed diets than StS and StH (P < 0.01). Mixed diets showed greater (P < 0.01) intake of most nutrients compared to CS diet, except for the intake of TDN and DOM, which were similar (P > 0.60). Corn silage showed greater (P < 0.01) digestibility of all nutrients than other diets. Stylosanthes silage and StH had greater (P ≤ 0.03) digestibility of DM, CP and NFC than mixed diets. Average daily gain (ADG) and carcass average daily gain (CADG) were greater (P ≤ 0.03) for CS diet than others, but mixed diets were similar (P ≥ 0.67) to CS. Mixed diets had greater (P < 0.01) ADG and CADG than StS and StH, while StS showed greater (P = 0.05) ADG compared to StH. Carcass yield was greater (P = 0.02) for StH compared to StS. Diets containing 50% CS and 50% StS or StH are alternatives to CS in ration of finishing beef cattle.

Short Communication: Effects of planting density on nutritive value, dry matter yield, and predicted milk yield of dairy cows from 2 brown midrib forage sorghum hybrids

ABSTRACT Objective Our objective was to evaluate the effects of 5 planting densities (148,000, 198,000, 247,000, 297,000, and 346,000 seeds/ha) on the nutritive value, DM yield, and predicted milk yield from 2 brachytic dwarf (shortening of plants by reducing length between internodes) brown midrib-6 forage sorghum hybrids (Advanta Seeds, AF7401; Advanta Seeds, ADV F7232; Irving, TX). Materials and Methods Replicated plots were planted and harvested on the same day. At harvest, weights of whole-plant sorghum forage were obtained to calculate DM yields. A commercial laboratory (Dairyland Laboratories Inc., Arcadia, WI) analyzed nutrients and predicted ruminal NDF digestibility at 30 h using near-infrared spectroscopy. Estimated milk yield per unit of forage and per hectare were calculated using Milk2006. Summative equations were used to predict TDN and NEl. Data were analyzed as a randomized complete block design with a 5 (planting density) × 2 (hybrid) factorial arrangement of treatments. Results and Discussion Differences were detected between hybrids for DM, starch and NDF concentrations, NDF digestibility at 30 h, DM yield (Mg/ha), kilograms of predicted milk per megagram of DM, and kilograms of predicted milk per hectare, highlighting the importance of hybrid selection. Because of increased tillering at lower planting densities, reductions in NDF concentration and uNDF240om were observed as well as a lack of effects on DM yield and predicted milk yields, emphasizing the tolerance of brachytic dwarf brown midrib-6 forage sorghum to decreases in planting density. Implications and Applications Because of greater DM yield and predicted milk yield, Advanta Seeds ADV F7232 outperformed Advanta Seeds AF7401. Furthermore, increasing planting density above 247,000 seeds∙ha−1 may not be feasible during a summer planting in Florida as biomass yield was not increased. Due to tillering, increasing planting density above 247,000 seeds∙ha−1 may be unnecessary and production costs may be reduced with the use of these reduced densities when similar hybrids are planted during the summer in the southeastern United States and grown under irrigation.

Enteric methane emission and digestion in dairy cows fed wheat or molasses

The aim of this experiment was to measure enteric methane (CH4) emission and its relation with rumen digestion in dairy cows fed diets rich in 1 of the 2 carbohydrate sources, starch or sugar. The rations were based on late first-cut grass-clover silage supplemented with wheat (Wh), NaOH-treated wheat (Wh+NaOH), sugar beet molasses (Mo), or sugar beet molasses with addition of sodium bicarbonate (Mo+Bic). Wheat and molasses made up 35% of dry matter in the 2 diets with molasses and wheat, respectively. Four cows fitted with ruminal, duodenal, and ileal canulae were used in a 4 × 4 Latin square design. Nutrient digestibility was measured using chromium oxide and titanium oxide as flow markers, and emissions of CH4 and hydrogen were measured via open-circuit indirect calorimetry on 4 consecutive days. Data were analyzed using PROC MIXED of SAS (version 9.4; SAS Institute Inc., Cary, NC) with treatment and period as fixed effects and cow as random effect. Furthermore, orthogonal contrasts were calculated. The cows produced 32.5, 33.6, 36.2, and 35.1 L of CH4/kg of dry matter intake (DMI) on diets Wh, Wh+NaOH, Mo, and Mo+Bic, respectively. The emission of CH4 per day, per kilogram of DMI, and per kilogram of energy-corrected milk as well as daily hydrogen emission were higher on the Mo diet compared with the Wh diet. With the present inclusion of wheat and molasses in the diet, no effects of NaOH treatment of wheat or of sodium bicarbonate supplementation to the Mo diet could be demonstrated on CH4 emission expressed per kilogram of DMI or per kilogram of energy-corrected milk. The duodenal flow of starch was higher when wheat was treated with NaOH. Under the conditions in the present experiment, ruminal NDF digestibility was not affected by carbohydrate source, NaOH treatment of wheat, or bicarbonate supplementation. Total volatile fatty acid concentration in the rumen and the proportions of acetate and propionate were not affected by carbohydrate source, NaOH treatment of wheat, or bicarbonate supplementation. Likewise, we could not show any influence of diet on microbial protein synthesis or efficiency of microbial protein synthesis expressed as grams of microbial protein synthesis per kilogram of true rumen-digested organic matter. We concluded that CH4 emission was increased when wheat was replaced by molasses, whereas no effect of manipulating rumen fermentation by NaOH treatment of wheat or addition of bicarbonate to molasses could be found with a level of approximately 25% of dry matter from starch and sugar, respectively.

Alfalfa leaves as a protein source: Replacement value of alfalfa leaves for soybean-meal protein in forage-based diets fed to mature ewes

Four ruminally and duodenally cannulated mature ewes (BW65.8 4.6kg) were used in a 4x4 Latin square designed experiment to investigate the replacement value of alfalfa leaves (AL) for soybean meal (SBM) protein. Ewes received basal diets consisting of bromegrass hay, cracked corn, and one of four protein supplements. Diets were formulated to be isonitrogenous by replacing SBM with AL on a nitrogenous basis. Supplement treatments were 100% SBM; 33.3% AL and 66.7% AL and 33.3% SBM and 100% AL. Experimental periods were 14 days with 10 days of diet adaptation followed by 4 days of ruminal, duodenal, and fecal sample collection. Replacing SBM with AL decreased intake of OM and NDF (quadratic; P&lt;.02). Intake of N increased as AL replaced SBM, which resulted in a cubic effect (P=.06). Organic matter flow and tru ruminal OM digestibility were not affected (P.18) by replacement of SBM with AL. Lower and total tract OM digestibility increased from the 33.3% AL to the 66.7% AL diet and decreased from the 66.7&amp; AL to the 100% AL dietary treatment resulting in cubic effects (P=.01 and .03, respectively). Nitrogen flow and true ruminal N digestibility were not influenced (P.18) by supplemental protein treatment. Greater lower tract N digestibility for 33 and 67% AL resulted in a quadratic effect (P=.05, whereas total tract N digestibility was not affected (p.13) by replacing SBM with AL. No treatment differences (P.20) were detected for NDF flow or ruminal NDF digestibility. Digestibility of NDF entering the small intestine tended to respond quadratically (P=.09) with a tendency for a cubic effect (P=.08) for tor total tract NDF digestibility as a result of greater digestibility of 66.7% ALdiet. Ruminal pH increased quadratically (P=.0004), while ruminal NH3, N tended to decrease linearly (p=.10) as AL replaced SBM. Ruminal particulate and fluid passage rates were not influenced (P .21) by replacing SBM with AL. Total VFA concentrations within the rumen decreased in a quadratic (P=.05) fashion. Acetate:propionate ratio responded quadratically (P=.0001) due to higher acetate:propionate ratios for diets containing a combination of supplementary protein. Alfalfa leaves can replace soybean meal as a protein supplement; however, greater nutritional value was apparent when the two protein sources constituted the supplement.

Botanical Composition and In Situ Dry Matter Degradability of Legume- Grass Mixture Pasture Fertilized with Different Amounts of Nitrogen

This study was conducted to determine the effects of different nitrogen (N) fertilizer levels on botanical composition, dry matter (DM) yield, chemical composition, in situ ruminal DM and NDF degradability and net energy lactation (NEL) of a native legume-grass mixture pasture. Field and degradability trials were arranged in a Complete Randomized Block Design with three replicates. Pasture was fertilized at six levels of N fertilizer (ammonium nitrate, N0, N50, N100, N150, N200 and N250 kg/ha). Three rumen cannulated Holstein Friesian heifers (3-4 year old) were used. Feed samples were incubated for 0, 8, 12, 24, 36, 48, 72 and 96 h. Application of nitrogen fertilizer results indicated that nitrogen fertilizer decreased the legumes ratio (LR) of pasture, approximately 22.4%, Although N fertilizer increased the grass ratio (GR) of pasture approximately 55.8%. Dry matter (DM), Net energy lactation (NEL, Mcal/kg) and ash contents of pasture were increased by increasing N fertilizer level. However, when N fertilizer level increased acid detergent fiber (ADF) concentration of pasture decreased. Application of the different rate of nitrogen fertilizer had no effect on in situ rumen degradability of DM and NDF of pasture. It was also found that there was the significant positive relationship between effective NDF degradability at 48 h. rumen incubation period and different level of N fertilizer. In addition, it was determined that there was a linear and quadratic positive relationship between DM yield and different nitrogen doses. In conclusion, different rates of nitrogen application changed botanical composition, decreased ADF content and increased NEL and effective rumen degradability of neutral detergent fiber (EDNDF 48 h.) of pasture.

Yield survey and nutritional evaluation of garlic stalk for ruminant feed

BackgroundVery limited information exists on the ruminal degradation kinetics of nutrients in garlic stalk. The present study aimed to survey the annual yield of garlic stalk in Korea and determine its feed-nutritive value for ruminants.MethodsIn Experiment 1, garlic stalk was incubated in situ in the rumen of two Hanwoo steers (360 ± 15 kg body weight) and removed after 12, 24, or 48 h to determine the ruminal degradation kinetics of DM and NDF. Rice straw was also included for comparison. In Experiment 2, In Experiment 2, six male Corriedale sheep were randomized to two dietary treatments to determine the apparent digestibility of nutrients in garlic stalk. Diets included a control ration without garlic stalk (60% concentrate mix +40% ryegrass) or a treatment ration (70% control diet +30% garlic stalk).ResultsThe Korean national yield of garlic stalk (sun-dried basis) in 2016 was estimated to be 31,910 tons, with the southern coastal regions producing the highest quantity. Compared with rice straw, garlic stalk had lower NDF, higher ADF, and greater effective degradabilities of DM and NDF, resulting in a greater TDN value (56.3%), which was higher than that obtained for rice straw (43.7%).ConclusionThese results provide basic information on the ruminal DM and NDF degradation kinetics of garlic stalk, which would be helpful for the efficient utilization of this by-product in ruminant diets.

583 Effects of lipid intake and degree of saturation on nutrient digestion and nitrogen balance in steers consuming corn-based diets

Increases in dietary lipid can augment energy density; however, lipids can mitigate ruminal fermentation of feed. We evaluated effects of amount and source of dietary lipid on nutrient digestibility, ruminal fermentation, and N balance in cattle consuming corn-based diets. Five steers (BW = 392 ± 15 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 × 5 Latin square with 12-d periods. Diets contained no added fat, or 4 or 8% added lipid from either a predominantly saturated (i.e., tallow) or predominantly unsaturated (i.e., linseed oil) source. Unsaturated fat decreased (P= 0.01) DMI compared to saturated fat and increasing amount of lipid supplementation tended (Linear= 0.14) to decrease DMI. Neither added amounts or source of lipid affected (P≥ 0.33) ruminal NDF digestion. However, increased diet lipid decreased ruminal DM digestibility (Linear= 0.04) and tended (Linear= 0.15) to decrease ruminal starch digestibility. Apparent (Linear= 0.03) and truly (Linear= 0.05) fermented OM in the rumen decreased in response to increased dietary lipid. Ruminal pH (P≥ 0.50), ammonia (P≥ 0.18) and total organic acid content (P≥ 0.31) were not affected by diet lipid. Additionally, amount and source of lipid had no effect on ruminal acetate (P≥ 0.21) or propionate (P≥ 0.21) concentrations; however, lipid amount tended (Linear= 0.07) to decrease acetate:propionate. Similarly, total tract digestion of DM (Linear<0.01), OM (Linear<0.01), and NDF (Linear= 0.02) were decreased by added dietary lipid. Greater lipid intake also tended (P= 0.12) to decrease total tract starch digestion. Unsaturated lipid tended (P= 0.06) to decrease total tract NDF digestibility, but saturated lipid tended to decrease total tract DM (P =0.12) and OM (P= 0.10) digestion. Microbial N flow to the duodenum was not affected (P≥ 0.18) by lipid, but microbial efficiency tended (Linear= 0.06) to increase with increased lipid intake. Fecal N excretion was decreased (P<0.01) by unsaturated lipid. Nitrogen balance (P≥ 0.28) and N efficiency (P≥ 0.58) were not affected by lipid source or amount.

Effects of intravenous lipopolysaccharide administration on feed intake, ruminal forage degradability, and liquid parameters and physiological responses in beef cattle.

This experiment compared DMI, ruminal forage degradability, and liquid parameters as well as physiological responses in beef cattle receiving a lipopolysaccharide (LPS) challenge or not. Eight ruminally cannulated Angus × Hereford steers (485 ± 16 kg BW) were housed in individual pens on d -7, ranked by BW, and allocated to 1 of 2 treatments administered on d 0: 1) an intravenous (i.v.) bolus dose (0.5 μg/kg of BW, diluted in 5 mL of 0.9% sterile saline) of bacterial LPS ( 0111:B4) or 2) a 5-mL i.v. injection of 0.9% sterile saline (CON). Steers had free-choice access to mixed alfalfa-grass hay, water, and a commercial vitamin + mineral mix during the experiment (d -7 to 6). Hay DMI was evaluated daily from d -5 to 6. Immediately prior to treatment administration (h 0), polyester bags containing 4 g of ground dietary hay (DM basis) were immersed into the rumen of each steer and incubated for 0, 4, 8, 12, 24, 36, and 48 h for DM and NDF degradability evaluation. Steers were also intraruminally pulse-dosed with 5 g of Co-EDTA immediately prior to treatment administration, and rumen fluid samples were collected at 0, 2, 4, 6, 8, 12, 16, and 24 h for ruminal liquid volume and dilution rate calculations. Blood was collected every 2 h from -2 to 8 h, every 4 h from 8 to 16 h, every 12 h from 24 to 72 h, and every 24 h from 96 to 144 h relative to treatment administration. Values obtained before treatment administration were used as a covariate within each respective analysis. Steers receiving LPS had less ( ≤ 0.03) DMI on d 0 and 1 compared with CON steers. Steers receiving LPS had reduced ( ≤ 0.05) rumen liquid volume and dilution rate as well as ruminal disappearance rate and effective degradability of DM and NDF compared with CON steers. Steers receiving LPS had greater ( ≤ 0.05) plasma tumor necrosis factor α at 2 h, greater plasma haptoglobin from 24 to 72 h, greater plasma cortisol from 12 to 16 h, greater serum NEFA from 6 to 48 h, greater plasma insulin and glucose at 2 h, reduced plasma glucose from 4 to 12 h, greater plasma cholecystokinin at 16 h, and greater plasma leptin concentrations at 8, 12, 16, 36, 48, and 60 h after treatment administration compared with CON steers. Hence, LPS administration transiently reduced DMI in steers via physiological reactions that modulate gastrointestinal motility and satiety centers in the central nervous system, in addition to potential host-microbiome endocrine interactions that impaired ruminal hay DM and NDF degradability.

Effects of intravenous lipopolysaccharide administration on feed intake, ruminal forage degradability, and liquid parameters and physiological responses in beef cattle

This experiment compared DMI, ruminal forage degradability, and liquid parameters as well as physiological responses in beef cattle receiving a lipopolysaccharide (LPS) challenge or not. Eight ruminally cannulated Angus × Hereford steers (485 ± 16 kg BW) were housed in individual pens on d −7, ranked by BW, and allocated to 1 of 2 treatments administered on d 0: 1) an intravenous (i.v.) bolus dose (0.5 μg/kg of BW, diluted in 5 mL of 0.9% sterile saline) of bacterial LPS (Escherichia coli 0111:B4) or 2) a 5-mL i.v. injection of 0.9% sterile saline (CON). Steers had free-choice access to mixed alfalfa–grass hay, water, and a commercial vitamin + mineral mix during the experiment (d −7 to 6). Hay DMI was evaluated daily from d −5 to 6. Immediately prior to treatment administration (h 0), polyester bags containing 4 g of ground dietary hay (DM basis) were immersed into the rumen of each steer and incubated for 0, 4, 8, 12, 24, 36, and 48 h for DM and NDF degradability evaluation. Steers were also intraruminally pulse-dosed with 5 g of Co-EDTA immediately prior to treatment administration, and rumen fluid samples were collected at 0, 2, 4, 6, 8, 12, 16, and 24 h for ruminal liquid volume and dilution rate calculations. Blood was collected every 2 h from −2 to 8 h, every 4 h from 8 to 16 h, every 12 h from 24 to 72 h, and every 24 h from 96 to 144 h relative to treatment administration. Values obtained before treatment administration were used as a covariate within each respective analysis. Steers receiving LPS had less (P ≤ 0.03) DMI on d 0 and 1 compared with CON steers. Steers receiving LPS had reduced (P ≤ 0.05) rumen liquid volume and dilution rate as well as ruminal disappearance rate and effective degradability of DM and NDF compared with CON steers. Steers receiving LPS had greater (P ≤ 0.05) plasma tumor necrosis factor α at 2 h, greater plasma haptoglobin from 24 to 72 h, greater plasma cortisol from 12 to 16 h, greater serum NEFA from 6 to 48 h, greater plasma insulin and glucose at 2 h, reduced plasma glucose from 4 to 12 h, greater plasma cholecystokinin at 16 h, and greater plasma leptin concentrations at 8, 12, 16, 36, 48, and 60 h after treatment administration compared with CON steers. Hence, LPS administration transiently reduced DMI in steers via physiological reactions that modulate gastrointestinal motility and satiety centers in the central nervous system, in addition to potential host–microbiome endocrine interactions that impaired ruminal hay DM and NDF degradability.

Effect of Additives on In Vitro Intestinal Utilizable Crude Protein in Dairy Cows and Mobile Bag Nutrient Digestibility of Corn, Alfalfa and Whole Barley Silages

An experiment was conducted to investigate the effect of additives on intestinal utilizable crude protein in dairy cows, and ruminal and post-ruminal nutrients disappearance of corn, alfalfa, and whole barley silages using in situ mobile bag technique. Alfalfa, whole crop corn and barley were harvested and chopped, and then treated with commercial biological and chemical additives; urea at 0.0, 10.8 and 21.6 g/kg DM in corn (CS0.0, CSU10.8 and CSU21.6, respectively) and whole barley (BS0.0, BSU10.8 and BSU21.6, respectively); Biomin® inoculant at 0.0, 800 and 9600 cfu/kg in corn (CS0.0, CSB800 and CSB9600, respectively) and at 0.0 and 800 cfu/kg in whole barley (BS0.0 and BSB800); formic acid at 0.0, 4 and 4.4 ml/kg in alfalfa (AS0.0, ASF4 and ASF4.4, respectively) and at 0.0 and 4 ml/kg (BS0.0 and BSF4) in whole barley. Urea caused the enhancement of in vitro intestinal utilizable crude protein (uCP) and its effectiveness (EuCP). in vitro intestinal utilizable crude protein was not affected by formic acid in whole barley silage, although treated alfalfa silages had higher uCP than AS0.0. Ruminal CP disappearance was higher for urea-treated corn and whole barley silages at both levels, although formic acid and Biomin® did not change it. Ruminal NDF disappearance was greater for urea-treated corn silages and BSU21.6 than CS0.0 and BS0.0. Post-ruminal disappearance of protein increased significantly in AS4.4 and reduced in urea-treated corn and whole barley silages (P<0.05). Utilizable CP at 8 h was higher for dry hays in comparison with those of silages in both alfalfa and whole barley (P<0.05). Results of the present study showed that, for the first time, silages treated with urea and formic acid had higher in vitro utilizable crude protein in dairy cow intestine compared with the untreated silages.

Effect of maturity at harvest for whole-crop barley and oat on dry matter intake, sorting, and digestibility when fed to beef cattle.

The objectives were to evaluate the effect of harvest maturity of whole-crop oat (Study 1) and whole-crop barley (Study 2) on forage intake and sorting, ruminal fermentation, ruminal digestibility, and total tract digestibility when fed to beef heifers. In Study 1, 3 ruminally cannulated heifers (417 ± 5 kg) were used in a 3 × 3 Latin square design with 24-d periods. Whole-crop oat forage harvested at the late milk (LMILK), hard dough (HD), or ripe (RP) stages was fed for ad libitum intake and heifers were supplemented (1% of BW) with alfalfa pellets, barley grain, canola meal, and a mineral and vitamin pellet. Maturity at harvest for whole-crop oat did not affect ( ≥ 0.058) forage intake, DE intake, amount of forage refused, ruminal short-chain fatty acid concentration, or digestibility of DM, OM, NDF, and ADF. Ruminal starch digestibility decreased ( < 0.001) from 92.6% at the LMILK stage to 90.0% at the RP stage, with total tract starch digestibility decreasing ( = 0.043) from 95.8% at the LMILK stage to 94.8% at the RP stage. Ruminal CP digestibility was reduced at the HD stage compared with the LMILK and RP stages ( < 0.001). Mean ruminal pH was greatest for the LMILK stage (6.36; = 0.003) compared with the HD and RP stages (6.30 and 6.28, respectively). In Study 2, 6 ruminally cannulated heifers (273 ± 16 kg) were used in a replicated 3 × 3 Latin square design with 24-d periods. Dietary treatments included ad libitum access to whole-crop barley harvested at the LMILK, HD, or RP stage and a constant rate (0.8% BW) of supplement containing alfalfa pellets, barley grain, canola meal, and a mineral and vitamin pellet. Dry matter intake, ruminal content mass, and feeding behavior were not affected by harvest maturity ( ≥ 0.16). There was a decrease in total tract digestibility of DM, OM, and NDF observed at the HD stage compared with the LMILK and RP stages ( ≤ 0.004). Ruminal NDF digestibility decreased from 69.7% at the LMILK stage to 54.4% at the HD stage and 54.9% at the RP stage ( = 0.001), whereas ruminal ADF digestibility decreased from 70.0% at the LMILK stage to 44.4% at the HD stage and 42.5% at the RP stage ( = 0.002). Minimum and mean ruminal pH were least for the LMILK stage, intermediate at the RP stage, and greatest at the HD stage ( = 0.016 and = 0.031, respectively). These data suggest that despite reductions in ruminal digestibility of NDF and ADF with advancing maturity, harvesting whole-crop oat and barley forage at the HD and RP stages of maturity did not negatively affect DMI, fermentation characteristics, or DE relative to whole-crop cereal forage harvested at the LMILK stage.

Effect of including high-lipid by-product pellets in substitution for barley grain and canola meal in finishing diets for beef cattle on ruminal fermentation and nutrient digestibility.

The objective was to determine the effect of replacing barley grain and canola meal with high-lipid by-product pellets (HLBP; 14.6% CP, 29.8% NDF, 9.0% fat, and 5.52 MJ NE/kg in DM) on DMI, ruminal fermentation, nutrient flow at the omasal canal, and nutrient digestibility. Four ruminally cannulated and ovariectomized Hereford × Gelbvieh heifers (initial BW of 631.9 ± 23.3 kg; mean ± SD) were used in a 4 × 4 Latin square design. Periods consisted of 28 d, including 10 d for diet transition, 11 d for dietary adaptation, and 7 d for measurements. Heifers were fed a typical finishing diet consisting of 89% of concentrate (barley grain and canola meal; CONT), 6% of barley silage, and 5% of mineral and vitamin supplement (on DM basis). Dietary treatments consisted of a CONT or diets where 30% (HLBP30), 60% (HLBP60), and 90% (HLBP90) of the barley grain and canola meal were replaced with HLBP. Dry matter intake was not affected by treatment ( > 0.10). Total short-chain fatty acid concentration and molar proportions of acetate, propionate, and butyrate ( > 0.10) among treatments and ruminal ammonia did not differ ( > 0.10) among treatments, and ruminal ammonia increased ( = 0.03) linearly with increasing HLBP inclusion rate in the diet. Mean and maximum pH increased, whereas the duration and area that pH was below 5.8, 5.5, and 5.2, thresholds used for mild, severe, and acute ruminal acidosis, respectively, decreased linearly ( ≤ 0.05) with increasing rates of inclusion of HLBP. Organic matter flow at the omasal canal increased linearly ( = 0.03) with increasing HLBP inclusion rate in the diet. However, OM digestibility coefficients and apparent ruminal NDF and ADF digestibility yielded negative values for some animals, especially those fed HLBP90, indicating that ruminal digestibility was underestimated. Total tract OM digestibility decreased linearly ( < 0.01) with increasing inclusion rates of HLBP. This study showed that HLBP inclusion in substitution for barley grain and canola meal linearly decreases the severity of ruminal acidosis in cattle fed a typical grain-based finishing diet. However, total tract nutrient digestibility was negatively affected.

Impact of ferulic acid esterase producing lactobacilli and fibrolytic enzymes on conservation characteristics, aerobic stability and fiber degradability of barley silage

The objective of this study was to determine the effects of applying ferulic acid esterase (FAE) producing inoculants or non-FAE inoculants in combination with exogenous fibrolytic enzymes (EFE) at ensiling on silage characteristics and nutritive value of whole barley crop (Hordeum vulgare). Barley (330 g DM/kg fresh crop) was harvested at early-dough, chopped and allocated to one of the following four treatments: untreated (Control), FAE producing Lactobacillus buchneri mixture inoculants (T1), none-FAE L. buchneri mixture inoculants (T2), and T2 plus EFE (T3). Inoculants were applied at 1 × 108 colony forming units/gram forage (cfu/g) and EFE at 424 U (xylanase) and 180 U (endoglucanase)/kg fresh weight. Forage was packed into 12 laboratory silos per treatment and ensiled for 7, 28 and 90 d. Subsamples at 90 d were used for in vitro, in situ and aerobic stability studies. After 90 d of ensiling, all inoculated silages had less (P < 0.001) water soluble carbohydrate, and greater (P < 0.001) DM loss as compared to the Control. For T1 and T2, aNDF was greater (P = 0.003) than Control and T3 silage. From d 0 to d 7 of ensiling, 16S rRNA copy numbers of L. buchneri in Control increased from 6.5 to 8.0 log10 copies/g, thereafter remaining stable, whereas it increased from 7.0 to 10.0 log10 copies/g in all inoculated silages, reaching ∼10.5 log10 copies/g after 28 d of ensiling. At this time, inoculated silages also had a higher (P < 0.001) pH, produced more acetic acid and ethanol, but less (P = 0.01) lactic acid than Control. After 21-d aerobic exposure, all inoculated silages remained stable, but Control silage deteriorated as indicated by a reduction (P < 0.001) in lactic acid and an increase (P < 0.001) in pH, and numbers of yeast. The T3 silage had less (P < 0.001) total gas production than other silages in in vitro ruminal fermentation. Compared to Control, the soluble fraction (a) of DM was less (P < 0.001) in T1 and T2, whereas it was greater (P < 0.001) in T3 silage. In situ NDF digestibility of T1 silage was greater (P < 0.01) than that of Control and T3 silage at 24 and 72 h of incubation. Inoculation of whole crop barley silage with inoculants containing FAE or non-FAE producing L. buchneri improved ruminal NDF digestibility, but a combination of EFE with a none-FAE L. buchneri reduced NDF degradability.

Using a fibrolytic enzyme in barley-based diets containing wheat dried distillers grains with solubles: ruminal fermentation, digestibility, and growth performance of feedlot steers.

Two experiments were conducted to evaluate the effects of adding an exogenous fibrolytic enzyme (FE) on ruminal pH and fermentation, digestibility, and growth performance of feedlot beef cattle fed a finishing diet containing wheat dried distillers grains with solubles (DDGS). In Exp. 1, 4 ruminally cannulated Angus heifers (average BW of 807 ± 93.9 kg) were used in a replicated 4 × 4 Latin square design. Treatments were 1) control (CON; 10% barley silage and 90% barley grain-based concentrate), 2) CON diet substituting 30% wheat DDGS for barley grain (WDG), 3) WDG diet supplemented with low FE (WDGL), and 4) WDG diet supplemented with high FE (WDGH). Heifers fed WDG had less (P = 0.01) total tract DM digestibility than heifers fed CON. Increasing FE linearly (P < 0.05) increased starch digestibility without affecting digestibility of other nutrients. Addition of FE also reduced (P = 0.03) ruminal ammonia-N (NH3-N) concentration but did not affect VFA concentration. Moreover, application of FE to wheat DDGS linearly increased in situ ruminal DM (P < 0.01) and NDF (P = 0.02) disappearance after 48 h of incubation. In Exp. 2, 160 yearling steers (initial BW = 495 ± 37.9 kg) were fed the same diets as in Exp. 1. No differences in DMI, final BW, ADG, dietary NEg, or carcass characteristics were observed among diets. However, the steers fed WDG had less (P < 0.05) G:F and greater number of (P < 0.01) abscessed livers than steers fed CON. Increasing FE application in wheat DDGS diets did not affect DMI, final BW, or ADG but tended (P < 0.09) to linearly improve feed efficiency and decreased (P = 0.03) the incidence of abscessed livers. These results demonstrated adverse effects of including wheat DDGS in finishing diets on feed digestion, feed efficiency, and animal health. Application of FE in wheat DDGS-based diets potentially improved starch digestion, protein metabolism in the rumen, feed efficiency, and animal health.

Digesta sampling sites and marker methods for estimation of ruminal outflow in bulls fed different proportions of corn silage or sugarcane.

The objective of this experiment was to assess ruminal outflow and apparent total-tract digestibility using digesta samples from 3 sites (reticulum, omasum, and abomasum) and 3 marker methods (single marker: indigestible NDF [iNDF; sample without separation]; double marker: iNDF + Co-EDTA [filtered sample]; and triple marker: iNDF + ytterbium [Yb] acetate + Co-EDTA [filtered and centrifuged]) in bulls fed corn silage and sugarcane-based diets. Eight crossbred (Holstein × Zebu) bulls (353 ± 37 kg of BW; 24 ± 1 mo of age) with ruminal and abomasal cannulas were randomly distributed into two 4 × 4 Latin squares that were balanced for residual effects. The following experimental diets were used: 1) 60% corn silage + 40% concentrate, 2) 40% corn silage + 60% concentrate, 3) 60% fresh sugarcane + 40% concentrate, and 4) 40% fresh sugarcane + 60% concentrate. Reticular, omasal, and abomasal digesta samples were collected at 9-h intervals over 3 d. At the end of the experiment, a composite sample was prepared for each bull, and these samples were subsequently assigned to the 3 marker methods. The concentrations of CP, NDF, and iNDF of reticular digesta differed (P < 0.01) from those of the omasum and abomasum. Use of omasal and abomasal samples led to similar estimates of ruminal outflow and ruminal digestibility for DM (P = 0.65), OM (P = 0.68), CP (P = 0.85), and NDF (P = 0.57). In contrast, the ruminal outflow of digesta based on reticular sampling appeared to be underestimated. We recommend sampling from the omasum because sampling from this region is less invasive than sampling from the abomasum. Although we did not observe differences in ruminal NDF digestibility among the different marker methods, we did observe that ruminal digestibility of CP was greater for the single marker method than for the double and triple marker methods; we therefore recommend the use of the double or triple marker method.

Comparative digestibility by cattle versus sheep: Effect of forage quality1,2

The objective was to determine the effect of forage quality on apparent total tract digestibility and ruminal fermentation in cattle versus sheep. Five yearling English crossbred (Hereford × Angus) steers (440.4 ± 35.6 kg of initial BW) and 5 yearling whiteface (Rambouillet × Columbia × Debouillet) wethers (44.4 ± 4.6 kg of initial BW), each fitted with a ruminal cannula, were randomly assigned to 1 of 3 forage sources within ruminant specie, and the study was conducted over 3 periods. For forage source, both animal and period served as the blocking factor with all forage sources represented once within each animal and all forage sources represented at least once within each period. The treatment structure was arranged in a 2 × 3 factorial with ruminant species (2) and forage source (3) as the factors. Forage sources were 1) alfalfa hay (Medicago sativa; 17.5% CP and 34.1% NDF, DM basis), 2) warm-season grass hay mix (Bothriochloa ischaemum and Cynodon dactylon; 7.3% CP and 74.7% NDF, DM basis), and 3) lovegrass hay (Eragrostis curvula; 2.5% CP and 81.9% NDF, DM basis). As a percent of BW, steers and wethers consumed similar (P ≤ 0.06) amounts of forage, and intake was more influenced by forage quality (P < 0.001) than ruminant species (P = 0.35). When expressed per unit of metabolic BW, cattle consumed more (P < 0.001) DM, NDF, and N than sheep. Apparent total tract digestibility was similar among steers and wethers when alfalfa or grass hay was fed, but decreased to a greater extent in wethers when low-quality lovegrass hay was fed (ruminant species × diet interaction, P ≤ 0.01). Rate (%/h) of ruminal NDF disappearance was greater (P = 0.02) for alfalfa and grass hay than lovegrass, but was not influenced (P = 0.12) by ruminant species. In addition, ruminal DM fill was influenced more (P < 0.01) by forage than by ruminant species (P = 0.07). Steers and wethers had greater (P < 0.01) DM fill from grass hay and lovegrass hay than alfalfa before and 5 h after feeding. Ruminal VFA were generally not influenced (P ≥ 0.06) by ruminant specie. Results suggest that apparent total tract digestibilities are more similar among ruminant species when moderate- to high-quality forages are evaluated. However, sheep are not an adequate model for cattle when low-quality forages are compared because cattle digest low-quality forages to a greater extent than sheep. Expressing digestibility as digestible intake per unit of BW allows for a wider range of forage qualities to be compared when substituting sheep for cattle.