Indigestible Neutral Detergent Fiber Research Articles

Effects of ensiling time on corn silage neutral detergent fiber degradability and relationship between laboratory fiber analyses and in vivo digestibility

Accurate analysis of degradability of silage neutral detergent fiber (NDF) is important for diet formulation and to predict lactational performance of dairy cows. In this study, 5 corn silage hybrids ensiled for 0 (unfermented), 30, 60, 120, and 150 d were used to determine the effects of ensiling time on silage neutral detergent fiber degradability (NDFD) and to assess the relationships between near-infrared reflectance spectroscopy (NIR) NDF-related analyses and in situ NDFD variables. In addition, the relationships between dietary concentration of indigestible NDF, 288-h incubation (iNDF288), or undegraded NDF, 240-h incubation (uNDF240), and in vivo total-tract apparent organic matter and NDF digestibility were studied in total mixed ration samples from 16 experiments with lactating dairy cows. Ensiling time had no effect on silage NDF concentration; however, the ratio of acid detergent fiber ÷ NDF increased, and estimated hemicellulose concentration decreased quadratically with ensiling time. Also, concentration of NDF-bound protein decreased, and that of lignin increased linearly with ensiling time. These changes in silage fiber composition resulted in a linear decrease in in situ effective degradability of silage NDF with increasing ensiling time. The indigestible fraction of NDF and concentration of structural carbohydrates were not affected by ensiling time. Correlations of in situ NDFD variables with laboratory NIR NDFD analyses were weak to moderate. The relationship of corn silage uNDF240 with lignin concentration or 30-h NDFD (all NIR analyses) was remarkably good (R2 = 0.73 and 0.88, respectively). The relationship between in situ iNDF288 concentration (but not uNDF240) and in vivo total-tract apparent digestibility of dietary organic matter and NDF was good (R2 = 0.72 and 0.80, respectively). In conclusion, in situ degradability of silage NDF linearly decreased from 0 to 150 d ensiling time, primarily caused by a decrease in concentrations of hemicellulose and NDF-bound protein. In situ NDF degradability measurements and common laboratory NIR NDF-related analyses were generally poorly correlated. We found a good relationship between in vivo NDF digestibility and dietary concentration of iNDF288 determined in situ, but the relationship with uNDF240 was poor.

Feeding a diet with corn distillers grain with solubles to dairy cows alters manure characteristics and ammonia and hydrogen sulfide emissions from manure

The objective of the experiment was to examine effects of a diet containing a high concentration (28.8% dry matter basis) of corn distillers grain with solubles on manure characteristics and NH3 and H2S emissions from dairy cow manure. Eighteen cows were blocked by parity and days in milk, and cows in each block were assigned to the following treatments: the control diet (CON) or CON with distillers grains with solubles at 28.8% (dry matter basis) replacing mainly soybean meal (DG). The experiment was conducted for 11 wk, and feces and urine from individual cows were collected over 3 d in wk 11 (a total of 8 spot samples per cow). Fecal or urine samples were composited by cow, and the composite feces and urine were analyzed for indigestible neutral detergent fiber and creatinine concentration, respectively, for individual cows to estimate total fecal and urine outputs. Immediately before the manure incubation, composited feces and urine were sampled to determine manure characteristics. Manure was reconstituted according to daily fecal and urine excretion estimated for individual cows. Individual manures were incubated using a continuous air flux multichamber system over 10 d to measure NH3 and H2S emissions. All data from 18 manures were analyzed using the Mixed procedure of SAS (SAS Institute Inc., Cary, NC). The ratio of feces to urine and the contents of manure total and volatile solids were not different among treatments. Urine from DG had lower pH and DG manure had lower N content and greater S content compared with CON. During the 10-d incubation, NH3 emission was considerably less for DG versus CON. The emission of H2S over 10 d for DG was greater compared with that for CON. After the incubation, manure pH and N and S concentrations were greater for DG versus CON. In conclusion, manure from cows fed a high-DG diet decreased urinary N contribution to manure N and lowered urine pH, which were the factors that caused the decrease in NH3 emission from DG manure. However, the DG diet increased dietary S concentration and increased S excretion in urine and feces. This increased H2S emission from DG manure during the 10-d manure incubation.

What is the maximum nitrogen in marandu palisadegrass fertilization?

AbstractThe absence of nutrient replacement, especially nitrogen (N), is one of the main causes of grazing system underutilization and tropical climate pasture degradation. Therefore, N is a very important nutrient in the pasture maintenance; however, it is necessary to know the maximum limit to be used of this nutrient, since fertilization increases production cost. Thus, the objective of this study was to identify the N dose that provides the highest production of marandu palisadegrass (Brachiaria brizantha cv. Marandu), and the fertilization effect on pasture degradation process and forage nutritive value. Treatments consisted in the application of : 0 (control), 25, 50, 75 and 100 kg N ha−1 cycle−1 of regrowth. The evaluations were carried out during the summers (November to April) of 2015/2016 and 2016/2017. The highest dry matter yield (DMY) and forage accumulation rate (FAR) occurred between doses of 50 and 75 kg ha−1 cycle−1, with no change in productive potential at higher doses. The reduction in mineral content and the increase in crude protein (CP) are the main changes in the nutritional value of marandu palisadegrass, with no pronounced effect on in vitro dry matter digestibility (IVDMD), indigestible neutral detergent fiber (iNDF) and potentially digestible dry matter proportions of CP in the cell wall (CPCW) and in cellular content (CPCC).The productive effect of nitrogen fertilization under marandu palisadegrass is the increase in DMY and FAR. Thus, the use of nitrogen fertilizers in pasture systems with marandu palisadegrass has a greater impact on the area gain than the individual gain, assuming these systems, the use of nitrogen doses of 50 to 75 kg ha−1 cycle−1.

Supplementation strategies affect the feed intake and performance of grazing replacement heifers.

The literature lacks studies investigating the performance of supplemented replacement heifers grazing on intensively managed warm-season pasture. Our objective was to evaluate the effects of supplement composition (energetic or protein) on the performance, muscle development, thermogenisis, nutrient intake, and digestibility of replacement Holstein heifers grazing Mombaça grass. Eighteen Holstein heifers with an average age and initial body weight (BW) of 12.57 ± 2.54 mo and 218.76 ±47.6 kg, respectively, were submitted to a randomized block design, with six replicates on a rotational grazing system of Panicum maximum cv. Mombaça pasture. Treatments were: control (CON; mineral salt ad libitum); energy supplement (ENE; corn meal as supplement, 8% CP and 3.78 Mcal/kg DE); and protein supplement (PRO; corn and soybean meal, 25% CP and 3.66 Mcal/kg DE). Supplements were individually fed at 0.5% BW. The experiment lasted 120 days, subdivided into three periods. Titanium dioxide and indigestible neutral detergent fiber (iNDF) were used to estimate the intakes and digestibility of the nutrients. BW, wither height, thoracic circumference, body length, and ultrasound of ribeye fat thickness measurements were taken once per period. Body condition score (BCS) was assessed twice during the experiment. The MIXED procedure of SAS, including period as a repeated measure, was used and significance was declared at P ≤ 0.05. Dry matter intake (DMI), CP intake (CPI) and DE intake were greater in heifers fed PRO compared to CON and ENE. Heifers supplemented with ENE had the lowest DMI. Treatment affected pasture intake/BW; it was similar between PRO and CON heifers, and lower for the ENE treatment. A treatment × period interaction was observed for NDF intake (%BW), in which heifers fed PRO and CON had the greatest NDF intake and ENE had the lowest. The digestibility of DM was the greatest in PRO-supplemented heifers and the lowest in CON heifers. Heifers fed ENE had decreased CP digestibility compared to PRO and CON heifers. Average daily gain (ADG) and thoracic circumference gain were greatest in the PRO treatment. BCS was greater in PRO compared to CON and ENE heifers. Supplementing Holstein heifers at 0.5% BW using PRO supplementation resulted in better animal performance, primarily greater ADG, than feeding ENE or not supplementing (CON). In conclusion, our results indicate that dairy heifers should be fed a protein supplement when grazing intensively managed Mombaça grass pasture.

Use of indigestible markers to estimate the apparent dry matter digestibility of diets containing a cocoa by-product

Fecal production and apparent dry matter digestibility (ADMD) were evaluated using external markers (chromium oxide; titanium dioxide; isolated, purified, and enriched lignin (LIPE®); and isolated, purified, and enriched lignin nanoparticles (NANOLIPE®) and internal markers (indigestible DM (IDM), indigestible neutral detergent fiber (INDF), and indigestible acid detergent fiber (IADF) in diets based on Tifton 85 bermuda grass (Cynodon sp.) hay containing different concentrations of a cocoa by-product. Sixteen crossbred (Holstein × Zebu) dairy heifers with a mean live weight of 363.00 ± 27.70 kg were evaluated and distributed in a completely randomized block design with a split-plot arrangement. The plots corresponded to the diets, which differed in the substitution of bermuda grass hay with different concentrations (0, 8, 16, and 24% of DM) of the cocoa by-product, whereas the splitplots represented the indigestible markers. Chromic oxide, LIPE®, NANOLIPE®, and INDF accurately estimated ADMD and fecal production whereas titanium dioxide, IDM, and IADF did not accurately estimate these parameters.

Isolation and identification of cellulolytic bacteria from gastrointestinal tract of Arabian horse and investigation of their effect on the nutritional value of wheat straw.

This study was conducted to isolate and identify the cellulolytic bacteria from gastrointestinal tract of Arabian horse and investigate their effect on the nutritional value of wheat straw (WS). Fresh faeces were collected from four Arabian horses. The cellulose-hydrolytic bacteria were isolated by using a medium amended with carboxymethyl cellulose (CMC). The activity of CMC was determined by measuring the release of reducing sugars from CMC. Among the isolates, four isolates (L11, L12, L2 and Z2) showed maximum hydrolysis capacity. 16S rRNA sequence analysis showed that these isolates possessed 99, 99, 99 and 98% similarity with Paenibacillus polymyxa, Paenibacillus polymyxa, Enterobacter cloacae and Escherichia coli respectively. Wheat straw was incubated with the isolated bacteria in liquid medium. Disappeared dry matter (DM) and crude protein (CP), neutral detergent fibre (NDF), indigestible NDF (iNDF) and acid detergent fibre (ADF) contents of WS were affected by microbial treatments (P<0·05). The highest disappearance of DM and CP contents and the lowest NDF, iNDF and ADF contents of WS were observed by treating with P. polymyxa L11. The values of NDF, iNDF and ADF were the highest and CP was the lowest in control. Gas production parameters and digestibility of processed samples were determined. Bacterial treatments enhanced (P<0·05) DM, OM, CP, NDF and ADF digestibility of WS. The highest and lowest (P<0·05) DM, OM, CP, NDF and ADF digestibilities were observed for WS treated with isolates L12 and control respectively. Potential of gas production (b), truly degraded organic matter (TDOM) and microbial biomass of bacteria treatments were significantly higher (P<0·05) compared to control. Generally, the results of this study showed that the isolated bacteria from horse faeces are capable of changing the chemical composition, increasing digestibility as well as enhancing nutrition value of WS. Wheat straw is a major agro-residue fed to ruminants. However, high fibre contents reduce digestibility and limit animal productivity. It seems that enhancement of ruminal degradation of these by-products is necessary. The results of this study revealed that cellulolytic bacteria isolated from gastrointestinal tract of horse can be used for biological treatment of WS.

Variation in rate of phenological development and morphology between red clover varieties: Implications for clover proportion and feed quality in mixed swards

AbstractRed clover (Trifolium pratense) grown in mixtures with grasses often constitutes a lower proportion of total yield in spring than in summer growth. A more even red clover proportion between the harvests would benefit forage quality and management at feeding. We investigated whether inclusion of early versus late‐maturing red clover varieties could reduce this disproportionality. In a two‐year field trial harvested three times per season, each of six red clover varieties was grown in two grass mixtures. Rate of phenological development did not differ during spring growth, but did so in regrowth after first and second cuts. Here, the earliest varieties constituted the highest proportion. At all harvests, the early varieties had lower crude protein concentrations and a higher content of neutral detergent fibre (NDF) and indigestible NDF than the late varieties. Clover proportion was higher in swards with a mixture of timothy and meadow fescue than in swards with perennial ryegrass during the first year and lower in the second year. It is concluded that developmental rate should be explored further as a key character for red clover competiveness in spring growth of rapidly elongating grasses.

Genetic parameters for cow-specific digestibility predicted by near infrared reflectance spectroscopy

Digestibility traits included in this study were dry matter digestibility (DMD, g/kg), which was calculated based on the indigestible neutral detergent fibre (iNDF, g/kg of dry matter) content in faeces (iNDFf) and in diet (iNDFd), and iNDFf predicted directly from faecal samples by near infrared reflectance spectroscopy (NIRS). The data set was collected at three research herds in Finland and one in Norway including in total 931 records from 328 lactating Nordic Red Cattle and Holstein cows. Observations were associated with different accuracy, due to the differences in sampling protocols used for collecting faecal samples. Heritability estimates varied between different sampling protocols and ranged from 0.14 ± 0.06 to 0.51 ± 0.24 for DMD and from 0.13 ± 0.05 to 0.48 ± 0.18 for iNDFf. Estimated genetic standard deviations were 10.5 g/kg and 6.2 g/kg dry matter for DMD and iNDFf, respectively. Results of our study indicated that recording only the iNDF content in the faeces is sufficient to determine genetic variation in cows’ ability to digest feed. The coefficient of genetic variation for DMD was rather small (1.7%), but could be utilized if it is supported by a positive analysis of benefits over costs.

Ruminal fatty acid outflow in dry cows fed different sources of linoleic acid: reticulum and omasum as alternative sampling sites to abomasum

ABSTRACTThis study was designed to determine the rumen outflow of fatty acids (FA) and biohydrogenation (BH) extent using alternative sampling sites (reticulum and omasum) to abomasum in dry cows fed different sources of FA. Four Holstein non-pregnant dry cows (≥3 parturitions, and 712 ± 125 kg BW), cannulated in the rumen and abomasum, were randomly assigned to a 4 × 4 Latin square design experiment, containing the following treatments: 1) control (CON); 2) soya bean oil (SO), dietary inclusion at 30 g/kg; 3) whole raw soya beans (WS), dietary inclusion at 160 g/kg; and 4) calcium salts of FA (CSFA), dietary inclusion at 32 g/kg. Rumen outflow of nutrients was estimated using the three markers reconstitution system (cobalt-EDTA, ytterbium chloride, and indigestible neutral detergent fibre [NDF]). Diets with FA sources decreased feed intake and increased FA intake. No differences in nutrient intake and digestibility were detected among cows fed diets supplemented with different FA sources. Diets with FA sources reduced the rumen outflow of DM and NDF, hence decreasing their passage rates. In addition, SO diet reduced the ruminal outflow of DM and NDF in comparison with WS and CSFA. Omasal sampling yielded the highest values of rumen outflow of NDF and potentially degradable NDF (pdNDF), whereas the reticular and abomasal samplings yielded intermediate and least values, respectively. The interaction effect between diet and sampling site was observed for rumen outflow of majority FA (except for C16:0, C18:0, and C18:2 trans-10, cis-12) and BH extension of C18:1 cis, C18:2, and C18:3. Calculations derived from abomasal sampling revealed that WS and CSFA diets had lower BH extent of C18:1 cis and C18:2 in comparison with SO, whereas cows fed CSFA had greater BH extent of C18:3 and lower BH extent of C18:1 cis compared to those fed WS. However, the latter results were not similar when calculations were performed based on the reticular and omasal samplings. Thus, there is evidence that neither reticular nor omasal samplings are suitable for estimating rumen outflow of FA in dry cows. In addition, WS and CSFA diets can increase the abomasal flow of polyunsaturated FA in dry cows.

Tracing back sheep diet composition feeding grass-legume mixtures using fecal δ13C

Stable isotopes can be an important research tool to track C and N in grazing experiments. This study tested different proportions of C4 grass and legume and the correlation between dietary δ13C with fecal δ13C. Forty lambs, male, with average body weight of 20.4 kg, were randomized in a complete block design and fed Tifton-85 (Cynodon spp.) and Alfalfa (Medicago sativa) hays, at different levels of substitution composing five treatments: 1) 100% Tifton-85 hay; 2) 75% Tifton-85 + 25% alfalfa hay; 3) 50% Tifton-85 + 50% alfalfa hay; 4) 75% alfalfa + 25% Tifton-85 hay; 5) 100% alfalfa hay. The trial lasted 27 days, consisting of 22 days for adaptation and 5 days for collection of orts, feed, and feces. Fecal samples were collected directly from the rectum, to avoid contamination. All samples were collected during the 5-d sampling period, being composited at the end. Feed and fecal samples were dried for 72 h in an oven (55ºC) and ground in a Willey mill to pass a 2-mm sieve, incubated for 288 h in situ to obtain the indigestibility. All collected samples were subjected to indigestible neutral detergent fiber (iNDF) and carbon stable isotope analysis. Dietary isotopic composition (δ13C) in the iNDF residue processing was −14.98, −18.22, −23.85, −25.99, and −30.64‰ for treatments 1–5, respectively. The δ13C of dietary samples iNDF treated was −17.41, −20.27, −26.06, −27.83, and −31.67‰, respectively for diets 1–5. Fecal δ13C for non-treated samples was −16.23, −20.79, −25.10, -28.8, and −32.31‰, and for iNDF-treated sample −16.65, −21.52, −26.25, 29.20, and −32.06‰, respectively, for diets 1–5. Fecal samples were more depleted than diet samples, and the iNDF changed the fecal δ13C. The models used to back calculate the diets predicted well the diets by fecal δ13C, and the best models had R2 of 0.98 using non-treated samples, with similar results found when using iNDF-treated samples (R2 = 0.97). There is a 13C discrimination between dietary and fecal samples, however, the proportion of C3 and C4 species in the diet can be accurately predicted based on fecal samples using δ13C. The use of iNDF treated samples did not improve the models, as well as the addition of digestibility and indigestibility in the models.

Evaluation of Brassica carinata meal on ruminant metabolism and apparent total tract digestibility of nutrients in beef steers1,2.

Brassica carinata is a new oilseed crop with the potential of producing high-quality jet biofuel. A high-protein meal (~40% crude protein) is obtained as a byproduct of hexane-solvent oil extraction; however, limited research is available on the use of this meal as a protein supplement for beef cattle. A duplicated 4 × 4 Latin square design was used to determine the effects of supplementation with B. carinata meal on ruminal fermentation, digestibility, and blood metabolites in beef cattle consuming bahiagrass hay (Paspalum notatum Flüggé), compared with frequently used protein supplements. Eight Angus crossbred steers (473 ± 119 kg initial BW) were randomly allocated to 8 pens, over 4 periods of 28-d each. Within period, steers were assigned to 1 of 4 treatments: 1) 1.62 kg/d cottonseed meal (CSM); 2) 2.15 kg/d dry distillers grains plus solubles (DDGS); 3) 1.39 kg/d B. carinata meal pellets (BCM); or 4) 1.17 kg/d soybean meal (SBM), supplemented daily, on an isonitrogenous basis. Steers had ad libitum access to bahiagrass hay and water. Intake was measured using the GrowSafe system. Following a 14-d adaptation, feed and fecal samples were collected to determine apparent total tract nutrient digestibility using indigestible NDF as an internal marker. Blood and ruminal fluid samples were collected before providing the protein supplements and then every 3 h, during a 24-h period, to analyze urea nitrogen (PUN) and glucose in plasma, as well as ruminal pH, ammonia nitrogen (NH3-N), and VFA concentrations. Data were analyzed using PROC MIXED of SAS with repeated measures. Model included the fixed effects of treatment, time, treatment × time, square, and period, and the random effects of steer(square) and steer(treatment). No effect of treatment (P > 0.05) was observed for pH, NH3-N, or glucose concentration. An effect of treatment (P < 0.01) was observed for PUN, with steers receiving SBM having greater concentrations. A treatment × time interaction was observed (P < 0.05) for total VFA concentration, acetate to propionate ratio, and molar proportions of acetate, propionate, butyrate, and valerate. Steers consuming SBM had greater molar proportions of branched-chain VFA (P < 0.01) compared with CSM and DDGS. There was no effect of treatment (P > 0.05) on intake or apparent total tract digestibility of nutrients. Brassica carinata performed similarly to commonly used protein supplements indicating its viability as a protein supplement for beef cattle.

Internal markers for predicting dry matter intake and digestibility in Santa Inês ewes on a pasture

AbstractAssessing feed intake is a valuable tool for herd management decisions. The use of markers is one of the most widely used techniques for estimating dry matter intake (DMI) in ruminants. Thus, internal markers (IM) were evaluated to predict DMI and digestibility (DMD) in ewes supplemented on a pasture during pre‐ (75, 105 and 135 days of gestation) and postpartum periods (30 and 60 days of lactation). The animals were kept on a pasture, and they were put into individual stalls to receive their supplementation. Twelve ewes were distributed in a completely randomized design: (a) Two supplementation levels (SL; 5 and 15 g/kg body weight, BW) and three IM (indigestible neutral detergent fiber, iNDF; indigestible acid detergent fiber, iADF; and rumen‐undegradable dry matter; RUDM) were used and analyzed as mixed models. (b) The DMI and DMD, which were estimated by the best marker, were analyzed as repeated measures using the mixed procedure in SAS. Fecal output was estimated using an external marker (LIPE®; isolated, purified and enriched lignin). The DMI and DMD estimated by RUDM were greater and better than iADF and iNDF, which were similar. The effects of SL and physiological stages for DMI and DMD were evaluated by the values obtained from RUDM. As expected, regardless of the physiological stage, DMI and DMD were greater in the animals that received 15 g/kg BW. Considering the physiological stage, the animals fed 15 g/kg BW had greater DMI and DMD at 75 days of gestation and 30 days of lactation and the least DMI was observed at 135 days of gestation and 60 days of lactation. In conclusion, RUDM provides the best estimates for DMI and DMD, which were greater in animals receiving 15 g/kg BW of concentrate at the beginning of gestation and lactation.

103 Post-ruminally delivered urea improves fiber utilization in ruminants.

Ruminants are able to transform non-protein nitrogen (NPN) into animal protein, but efficiency may depend on the site of delivery in the gastrointestinal tract. We hypothesized that post-ruminal NPN supply can be utilized in the rumen, via urea recycling. Four rumen fistulated Holstein heifers (561 ± 42Kg BW) were used in a Latin square design with ruminal and abomasal infusions. Treatments consisted of ammonium hydroxide solution constantly infused into the rumen (AR), or the abomasum (AA), urea solution constantly infused into the abomasum (UA) or urea supplied into the rumen as daily pulse dose (UR). Experimental periods consisted of 12 d for treatment administration and sampling followed by 2 d rest. Treatments were isonitrogenous (59 g N/d) and all heifers were fed hay (6% CP, 70% NDF) ad libitum with 1kg of compound feed (21.7% CP) supplied in the morning through rumen cannula. Indigestible NDF (iNDF) was used as faecal marker. Ruminal pH was analysed to fit a logistic model resulting in two parameters: slope corresponding to the range of cumulative pH and inflection point corresponding to the statistical median. Dry matter intake was highest (P=0.03) for heifers receiving UR or UA while AR led to lowest intake. Higher NDF digestibility was observed with UA compared to UR (P=0.05). The pH inflection point was higher (P=0.05) with AR compared to UR, AA, and UA. The pH range with UR was wider (lower slope; P=0.04), due to the rise in pH following urea infusion, in which ammonia concentration reached 63 mg/dL 3 hours after UR supply, while concentrations for AR, AA and UA were held constant (18.5 ± 3.1, 4.4 ± 0.8, 4.6 ± 1.0 mg/dL, respectively). Our study indicates that urea delivered post-ruminally improves fiber digestibility and rumen stability and offers a unique approach towards improving N utilization and efficiency in ruminant production systems.

Cutting ages of elephant grass for chopped hay production1

ABSTRACT With the advancement of the cutting age, there is an increase in the forage yield of elephant grass (Pennisetum purpureum), but there is also a reduction of the protein levels and digestibility of this forage. This study aimed to identify the ideal cutting age of elephant grass forage (BRS Canará cultivar) to chopped hay production. The experimental design was a randomized block, with five treatments (42, 60, 76, 91 and 105 days of growing) and four replicates. Forage agronomical, morphological and chemical characteristics were evaluated. A linear positive effect of the cutting age was observed on plant height, senescent material and yield of the chopped hay. The leaf percentage and leaf:stem ratio were reduced by the advance in the cutting age. There was also a linear positive effect of the cutting ages on indigestible neutral detergent fiber, neutral detergent fiber corrected for ash and protein and neutral detergent insoluble protein, with increases of 17.13 %, 16.63 % and 20.66 %, respectively. The contents of ashes, crude protein, total digestible nutrients and net lactation energy were reduced with the advance in the forage age. From 76 days, the ashes contents reached values below 9.29 % and the crude protein below 7.16 %. In the same cutting age, the chopped hay yield was 12.91 t ha-1. To improve the hay quality and production, the BRS Canará cultivar must be harvest between 60 and 76 days, when the plants are with 1.20-1.50 m of height, leaf:stem ratio of 0.55-0.44, crude protein of 8.29-7.16 % and indigestible neutral detergent fiber of 26.21-29.06 %.

Development of an in vitro method to determine rumen undigested aNDFom for use in feed evaluation

A portion of the forage cell wall, defined as neutral detergent fiber (NDF), is indigestible to anaerobic microbial digestion in ruminants. This fraction has been characterized by surface area relationships between acid detergent lignin, but recently, data have been published describing the dynamic nature of this relationship. In situ approaches have been described to estimate indigestible NDF, recovering the undigested NDF after long-term fermentations (uNDF). To be applicable to nutritionists and diet formulation, determining uNDF needs to be conducted in a commercial laboratory similar to other routine analyses of forage chemistry. A series of studies were conducted to evaluate an in vitro approach, to describe uNDF, which is repeatable and adaptable for routine feed evaluation. One hundred and two forages of several species were analyzed for NDF, acid detergent lignin, and uNDF. The uNDF was estimated by several approaches involving long-term fermentations and filtration steps to evaluate the length of time necessary to exhaust the digestible NDF and a filtration method necessary to maintain sample integrity by ensuring low sample loss and uniform recovery with residues from long-term in vitro fermentation. To determine uNDF, in vitro fermentations were conducted on 0.50 or 0.75 g of dry matter samples, in triplicate, at multiple time points up to 504 h and initially used Gooch crucibles with Celite (Thermo Fisher Scientific, Waltham, MA) as a filtering aid. The final method utilized a 1.5-µm pore size glass microfiber filter, which allowed for increased repeatability and improved sample recovery (lowest standard deviation). In this study, in vitro fermentations of 240 h were adequate to characterize and identify uNDF, which was repeatable among conventional forages provided the samples, after NDF analyses, were filtered through the same glass fiber filter. This approach could be adapted by commercial laboratories and would provide opportunities to develop near-infrared reflectance spectroscopy equations and calibrations.

Effects of two equine digestive aid supplements on hindgut health.

Gastrointestinal disease is the number one killer of horses. Little is known about the maintenance of microbes in the equine hindgut and how to distinguish a healthy gut in a live horse. Utilization of internal and external digestibility markers and starch fermentation has been extensively studied in ruminants and is the basis for research conducted on horses. The aims of this study were to investigate the effects of two equine feed digestive aid supplements on hindgut health (HGH) as reflected in fecal pH and digestibility and to compare and validate DM digestibility measurements through the use of internal and external markers such as chromium oxide (CR), lignin (Lig), indigestible ADF (iADF), indigestible NDF (iNDF), and indigestible lignin (iLig). Nine mature Quarter horses (six geldings, three mares) were used in a crossover design, three feeding periods of 17 d (51 d total), using three treatments: control, no feed additive (CON), Smartpak (SP; Plymouth, MA), or Platinum Performance (PP; Buellton, CA). Both SP and PP contained a strain of Lactobacillus, whereas SP further supplied mannanoligosaccharides (MOS) and fructooligosaccharides (FOS) and PP supplied Saccharomyces boulardii. Within the 17-d period, horses were offered orchard grass hay and sweet cob grain and the assigned treatment daily and four CR cookies to deliver 8 g/d of CR for the last 7 d of each period. Total feces were collected from 15 to 17 d. Feed and fecal samples were dried, ground, and sent to ANALAB (Fulton, IL) for nutrient analysis. Duplicate samples of feed and feces were placed in ruminally cannulated cows for in situ determination of iADF, iNDF, and iLig to estimate digestibility. Estimated CR fecal output, CR DMI, and DM digestibilities were evaluated using the root mean square prediction error percentage of the observed mean (RMSPE), concordance correlation coefficient (CCC), and Nash–Sutcliffe efficiency methods. Marker predictive ability tests showed iADF to have the least amount of bias with the smallest RMSPE (4%), largest CCC (0.43), and the largest amount of random bias (error of dispersion = 0.45). Supplementation of PP decreased CR DM digestibility (P < 0.02). Smartpak increased fecal pH (P < 0.09), but PP had no effect on fecal pH. Therefore, SP had a beneficial effect on HGH that is believed to be due to MOS and FOS.

Prediction of indigestible NDF in South African and Australian forages from cell wall characteristics

A portion of the forage cell wall is unavailable to microbial digestion in ruminants and in previous work this fraction was characterized by the relationship between lignin (sa) and neutral detergent fiber (NDF) as 2.4 × lignin and termed the indigestible NDF (iNDF). Further, this relationship was considered to be a static relationship between lignin (sa) and NDF with no genetic variation or observed effects of growing conditions on the plant. The objectives of this work were to further characterize the relationship between lignin and iNDF and to evaluate the concept of a fixed value, assuming that the relationship is more dynamic and dependent on agronomic and environmental factors. A further objective was to predict iNDF from cell wall composition. More than two hundred samples of several forage species from Australia and South Africa were analyzed for NDF, acid detergent fiber, lignin and iNDF. Forages were classified according to origins, type and species. The ratios of iNDF to ADL ranged between 1.6 and 8.0, demonstrating the dynamic nature of the relationship. Further, an attempt to predict iNDF based on the relationship between ADL/NDF and the ratio was made and the equations provided R2 values between 0.82 and 0.95, indicating that a prediction is possible, especially when considering one species at a time and more information within forage group and single forages on agronomic and environmental conditions would explain the extra variation. A single value of the ratio iNDF to ADL does not allow proper estimation of the size of the potentially digestible NDF and its rate of digestion, but species-specific equations can be developed and be effective in predicting iNDF. Long-term fermentations should however be preferred to correctly quantify these values and, if not available, data should allow for specific equations or near infrared spectroscopy calibration equations.

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.

Protein value and degradation characteristics of pulp fibre fractions from screw pressed grass, clover, and lucerne

Biorefinery of grassland plants may enable the production of feed for both ruminants and monogastrics at the same time. The pulp fibre fraction from twin-screw processed white clover, red clover, lucerne, and perennial ryegrass, is a major side-stream commonly considered of low value. However, it maintains a crude protein (CP) fraction of which a high proportion is expected to be fibre-associated. The pulp is expected to be suitable as forage for ruminants but knowledge of the feed value is limited.The objectives of this study were to assess the protein degradation in the rumen and the protein value of pulp compared to the original plant material, and to study the protein distribution among fibre fractions in order to evaluate the pulp as a source of forage for dairy cows.The ash concentration in the pulp was 51.1–72.3 g/kg DM compared to 86.3–104 g/kg DM in the original plant, while the in vitro digestible organic matter (DOM) in dry matter (DM) did not decrease significantly in pulp (532–689 g/kg DM) compared to plant (564–694 g/kg DM). Neutral detergent fibre (aNDF) concentration was higher in pulp (529–694 g/kg DM) than in original plant (342–503 g/kg DM), while the CP concentration of the aNDF from pulp (77.8–186 g/kg aNDF) did not differ from the concentration found in the plant aNDF (74.7–137 g/kg aNDF). Furthermore, the total amino acid (AA) concentration increased in pulp (825 g/kg CP) compared to original plant (768 g/kg CP), and the individual concentration of all essential AA in DM increased.The in situ rumen degradation of CP showed that the potentially degradable fraction was not different between plant (889–953 g/kg) and pulp (817–939 g/kg), although the fractional rate of degradation was lower in the pulp (0.093–0.109 h−1) than in the plant (0.113–0.192 h−1). Thus effective degradability (ED) of CP was lower in pulp (579–647 g/kg) than in plant (657–786 g/kg) increasing rumen escape protein (REP). The intestinal digestibility of REP was similar, thus a higher proportion of the pulp CP (225–256 g/kg) was digested in the intestine compared to plant CP (125–190 g/kg). The indigestible neutral detergent fibre (INDF) proportion of aNDF was not different between plant (88.1–422 g/kg aNDF) and pulp (85.3–460 g/kg aNDF).This study demonstrated that pulp from twin-screw pressing of white clover, red clover, lucerne, and perennial ryegrass has a protein concentration and value for ruminants, which is similar to the original plant material.

Technical note: A comparison of alkali treatment methods to improve neutral detergent fiber digestibility of corn stover

The objective of this study was to compare neutral detergent fiber (NDF) digestibility of corn stover that had been treated by 2 alkali treatment methods. Two experiments were conducted to test a sodium hydroxide (NaOH) treatment method that uses an ethanol/water co-solvent (NaOH/ethanol-H2O, United States Patent No. 20140220228) and a calcium hydroxide (CaOH) treatment method, which uses water as a solvent (CaOH/H2O). An in situ trial was conducted to compare NDF digestion kinetics between NaOH/ethanol-H2O-treated stover, CaOH/H2O-treated stover, untreated corn stover, and soy hulls. The digestion rate of potentially digestible NDF (kd) of NaOH/ethanol-H2O-treated corn stover (5.36%/h) was higher than CaOH/H2O-treated stover (2.27%/h), or untreated corn stover (1.76%/h) and similar to the kd of soy hulls (4.93%/h). The indigestible NDF (iNDF) fraction of untreated corn stover (35.1% of NDF) was reduced by CaOH/H2O treatment (27.3% of NDF) and by NaOH/ethanol-H2O treatment (2.8% of NDF). The iNDF fraction in soy hulls (3.6% of NDF) was similar to iNDF of NaOH/ethanol-H2O-treated stover. An in vivo digestibility trial was also conducted to compare fiber digestibility of diets supplemented with untreated corn stover, NaOH/ethanol-H2O-treated corn stover, or soy hulls. Total-tract apparent dry matter (DM) and NDF digestibility were measured with 8 lactating Holstein cows in a replicated 4 × 4 Latin square with four 21-d periods. Apparent DM digestibility (DMD) was improved when supplemental soy hulls were added to the base diet (60.0% DMD) compared with the base diet with no supplemental fiber (57.7% DMD). Apparent DM digestibility was reduced when diets were supplemented with untreated stover (52.4%). Dry matter digestibility of NaOH/ethanol-H2O-treated stover was similar (54.8% DMD) to all other treatments. Digestibility of NDF was lowest when cows were fed the diet with supplemented untreated stover (35.5% of NDF), and improved when soy hulls (40.6% of NDF) or NaOH/ethanol-H2O-treated stover (43.8% of NDF) were added to the diets. The NaOH/ethanol-H2O treatment process improves the DM and NDF digestibility of corn stover to values similar to those of soy hulls.