Amylase-treated Neutral Detergent Fiber Research Articles

Fecal amylase-treated neutral detergent fiber and ash contents as independent variables can predict metabolizable energy and coefficient of energy digestibility of diets for growing pigs without dietary information

The objectives of the present study were to develop prediction equations for digestible energy (DE), metabolizable energy (ME), and coefficient of energy digestibility (ED) of swine diets using fecal nutrients as independent variables without dietary information and to validate the prediction equations. A total of 262 fecal samples obtained from growing pigs fed 27 diets in 4 experiments were used to develop prediction equations for DE, ME, and ED. These equations were validated using 95 fecal samples obtained from growing pigs fed 12 diets in an additional experiment. The diets were based mainly on corn, soybean meal, and other plant-originated feed ingredients. In the digestibility experiments, feces and urine were quantitatively collected using the marker-to-marker procedure. Diet and fecal samples were analyzed for dry matter (DM), crude protein, ash, and amylase-treated neutral detergent fiber (aNDF). The DE of the 27 diets ranged from 12,164 to 18,301 kJ/kg DM and ME of 24 diets ranged from 11,603 to 16,657 kJ/kg DM. Coefficients of ED for the 27 diets ranged from 0.667 to 0.919. Fecal ash was positively correlated with DE (r = 0.81; P < 0.001), ME (r = 0.66; P < 0.001), and coefficient of ED (r = 0.67; P < 0.001) whereas fecal aNDF was negatively correlated with DE (r = –0.66; P < 0.001), ME (r = –0.74; P < 0.001), and coefficient of ED (r = –0.67; P < 0.001). The prediction equations developed using fecal nutrients were: DE (kJ/kg DM) = 15,077 + (13.72 × ash) – (4.65 × aNDF) (R2 = 0.71; P < 0.001); ME (kJ/kg DM) = 17,067 + (6.54 × ash) – (7.56 × aNDF) (R2 = 0.63; P < 0.001); and coefficient of ED = 0.881 + (0.00037 × ash) – (0.00028 × aNDF) (R2 = 0.57; P < 0.001) where nutrients are expressed as g/kg DM. Based on the regression analysis for validation of the equations, the prediction equations for DE and coefficient of ED using only fecal aNDF did not have mean bias or linear bias. In conclusion, DE values, ME values, and coefficient of ED for swine diets are correlated with fecal ash and aNDF concentrations and the energy values can be predicted using fecal ash and aNDF concentrations without dietary information.

Parity and nutrient total-tract digestibility in dairy cows during transition period

Cows experience many physiological, nutritional and social changes during transition period. This study aims to evaluate the differences in nutrients total-tract digestibility (nTTD) between primiparous (PP) and multiparous (MP) cows through the transition period. From -23, -5, 0, 7, 14, and 30 days from calving a sample of feed and feces samples were collected from 25 Holstein cows (11 PP and 14 MP) as well as daily rumination time through accelerometers.The results show that average nTTD were different (p ≤ 0.02) for amylase-treated neutral detergent fiber organic matter (aNDFom) and potentially digestible neutral detergent fiber (pdNDF240; 52.5 vs. 54.0 and 78.8 vs. 81.3, respectively in PP vs. MP), while no differences were found regarding pdNDF24 and starch (88.5 vs. 88.6 and 95.1 vs. 96.1, respectively in PP vs. MP). Total-tract starch digestibility (TTstarchD) was different among timepoints (p < 0.01), going from an average of 91.40 up to 97.39% of starch, on times -23 and 14, respectively. Differences in total-tract digestibility of aNDFom among timepoints (p < 0.01) was expected because of differences in diet composition among lactating and non-lactating cows. No differences in daily rumination time (p = 0.92), TTstarchD and total-tract potentially digestible NDF digestibility at 24 h (TTpdNDF24D) were recorded. Our findings show that fiber digestibility during the transition period is higher in MP probably for a different ruminal retention time. These differences should be considered when formulating rations for groups with different parity number.

Effects of endosperm type and storage length of whole-plant corn silage on nitrogen fraction, fermentation products, zein profile, and starch digestibility

Zeins are commercially important proteins found in corn endosperms. The objective of this study was to evaluate the effect of altering zein levels in corn inbred lines carrying endosperm mutations with differential allelic dosage and analyze the effects on the composition, nutritive value, and starch digestibility of whole-plant corn silage (WPCS) at 5 storage lengths. Three inbred lines carrying 3 different endosperm modifiers (opaque-2 [o2], floury-2 [fl2], and soft endosperm-1 [h1]) were pollinated with 2 pollen sources to form pairs of near-isogenic lines with either 2 or 3 doses of the mutant allele for each endosperm modifier. The experiment was designed as a split-plot design with 3 replications. Pollinated genotype was the main plot factor, and storage length was the subplot-level factor. Agronomic precautions were taken to mimic hybrid WPCS to the extent possible. Samples were collected at approximately 30% dry matter (DM) using a forage harvester and ensiled in heat-sealed plastic bags for 0, 30, 60, 120, and 240 d. Thus, the experiment consisted of 30 treatments (6 genotypes × 5 storage lengths) and 90 ensiling units (3 replications per treatment). Measurements included nutrient analysis, including crude protein, soluble crude protein, amylase-treated neutral detergent fiber, acid detergent fiber, lignin, starch, fermentation end products, zein concentration, and in vitro starch digestibility (ivSD). The nutritional profile of the inbred-based silage samples was similar to hybrid values reported in literature. Significant differences were found in fresh (unfermented) sample kernels for endosperm vitreousness and zein profiles between and within isogenic pairs. The o2 homozygous (3 doses of mutant allele) had the highest reduction in vitreousness level (74.5 to 38%) and zein concentration (6.2 to 4.7% of DM) compared with the heterozygous counterpart (2 doses of mutant allele). All genotypes showed significant reduction of total zeins and α-zeins during progressive storage length. In vitro starch digestibility increased with storage length and had significant effects of genotype and storage length but not for genotype by storage length interaction, which suggests that the storage period did not attenuate the difference in ivSD between near-isogenic pairs caused by zeins in WPCS. Both total zeins and α-zeins showed a strong negative correlation with ivSD, which agrees with the general hypothesis that the degradation of zeins increases ruminal starch degradability. Homozygous o2 was the only mutant with significantly higher ivSD compared with the heterozygous version, which suggests that, if all other conditions remain constant in a WPCS systems, substantial reductions in endosperm α-zeins are required to significantly improve ivSD in the silo.

Reducing dietary sodium of dairy cows fed a low-roughages diet affect intake and feed efficiency, but not yield.

Wastewater from dairy farms has become a major environmental and economical concern. Sodium residue in treated and untreated wastewater from dairy farms used for irrigation can lead to soil and groundwater salinization, with the risk of soil degradation. We examined the effect of reducing sodium fed to mid to late lactating cows from 0.61% (high sodium [HS]) to 0.45% (low sodium [LS]) of dry matter on dry matter intake (DMI), milk and milk-component yields, eating behavior, apparent total track digestibility, feed efficiency, and sodium excretion into the environment. We randomly assigned 28 multiparous high-yielding ( > 35kg milk/d) cows to 1 of 2 treatment groups (LS or HS) in a crossover design, with 7d of adaptation and 28d of data collection. Reducing sodium in the diet reduced sodium intake from 171 to 123g/d while lowering sodium excreted in the manure by 22%. Energy corrected milk (ECM) yield (37.4kg/d) and sodium excretion in the milk (33.7g/d) were similar for both groups. The DMI of LS cows was lower than that of HS cows (27.3 vs. 28kg/d) and consequently, feed efficiency of the LS cows was higher (1.40 vs. 1.35 ECM/DMI). Eating rate, meal and visit frequency, and eating time were similar for both treatments; meal and visit duration were longer for the HS cows, and meal and visit sizes tended to be larger. Digestibility of DM and amylase-treated neutral detergent fiber remained similar. Based on the results of this study, and discussed considerations, we recommend lowering the dietary sodium content for mid to late lactating cows in commercial herds to 0.52% of DM, in order to reduce sodium excretion to the environment via urine.

Effects of small-scale silo types and additives on silage fermentation and bacterial community of high moisture alfalfa on the Qinghai-Tibetan Plateau

Alfalfa is cultivated throughout the world, but its preservation remains challenging to small farms in cold climates. This study aimed to investigate the effects of small-scale silo types and additives on the silage quality of high moisture alfalfa on the Qinghai-Tibetan Plateau. Alfalfa with moisture of about 80% was ensiled in small farm bucket silos (FBS) or wrapped bale silos (WBS) at ambient temperature (5–15 °C) for 180 days. At ensiling, forage was treated without any additive (CK) or with a chemical additive (SB; a mixture of sodium benzoate, potassium sorbate, and sodium nitrite) or a lactic acid bacteria (LAB) inoculant (PBB; a mixture of Lactiplantibacillus plantarum, Bifidobacterium brevis and Pediococcus pentosaceus). Among the CK silages, higher (P < 0.05) acetic acid levels, bacterial diversity indices and relative abundance of L. plantarum were found in WBS vs FBS. Overall, silage treated with SB had the highest crude protein (CP) content, the lowest amylase-treated neutral detergent fiber (aNDF) and acid detergent fiber (ADF) contents and dry matter (DM) loss. Compared with CK, treatments with SB and PBB increased (P < 0.05) lactic acid content and decreased (P < 0.05) final pH value and butyric acid content of silage. In addition, treatment with PBB reduced (P < 0.05) the relative abundance of Lactilactobacillus sakei and increased (P < 0.05) the similarity of silage samples from different silos. There was negligible difference in fermentation quality of silage occurred between the types of silos. However, small WBS tended to increase the relative abundance of L. plantarum for more desirable silage fermentation. Application of additives at ensiling enhanced the preservation of silage nutrients with low DM loss. Based on the above results, small WBS were recommended for producing high-quality alfalfa silage on the Qinghai-Tibetan Plateau.

Near infrared spectroscopy calibration strategies to predict multiple nutritional parameters of pasture species from different functional groups

Near infrared reflectance (NIR) spectroscopy has been used by the agricultural industry as a rapid and inexpensive technique to quantify nutritional chemistry in plants. The aim of this study was to evaluate the performance of NIR calibrations in predicting the nutritional composition of ten pasture species that underpin livestock industries in many countries. The species comprised a range of functional diversity (C3 legumes; C3/C4 grasses; annuals/perennials) and origins (tropical/temperate; introduced/native) that grew under varied environmental conditions (control and experimentally induced warming and drought) over a period of more than two years ( n = 2622). A maximal calibration set including 391 samples was used to develop and evaluate calibrations for all ten pasture species (global calibrations), as well as for subsets comprised of the plant functional groups. This study found that the global calibrations were appropriate to predict the six key nutritional quality parameters for the studied pasture species, with the highest estimation quality found for ash (ASH), crude protein (CP), amylase-treated neutral detergent fibre (aNDF) and acid detergent fibre (ADF), and the lowest for ether extract (EE) and acid detergent lignin (ADL) parameters. The plant functional group calibrations for C3 grasses performed better than the global calibrations for ASH, CP, ADF and EE parameters, whereas for C3 legumes and C4 grasses the functional group calibrations performed less well than the global calibrations for all nutritional parameters of these groups. Additionally, the calibrations were able to capture the range of variation in forage nutritional quality caused by future climate scenarios of warming and severe drought.

Pilot Study on Predictive Traits of Fresh Maize Hybrids for Estimating Milk and Biogas Production

Farmers need information on which maize hybrid is best and under what conditions. They demand that this information be clear, simple and easily understood. This study aims to estimate the potential for milk production (MPP) and the biochemical methane potential (BMP) production from fresh maize hybrids. Using these indicators from fresh maize, information on the differences between hybrids can be effectively obtained, albeit with some of the shortcomings of this proposed method. Samples of fresh maize plants (n = 384) from four hybrids were evaluated at two locations over four consecutive years (from 2018 to 2021). The dry matter content, averaged across all hybrids, all years and both locations, was 371 ± 42.3 g.kg−1. The colder and wetter the year, the significantly higher the starch content, lower the amylase-treated neutral detergent fibre content (aNDF) and lower the crude protein (CP), which was reflected in lower BMP. Weather did not significantly affect the net energy of lactation (NEL) or MPP values. The location significantly affected all monitored indicators, except BMP. The earlier the hybrid was at harvest time, the lower the NEL and MPP but the higher BMP contents were. This study is preliminary and must be repeated with more hybrids and under more different conditions.

Fresh cassava root replacing cassava chip could enhance milk production of lactating dairy cows fed diets based on high sulfur-containing pellet

The experiment objective was to assess the shifting effect from cassava chip (CC) to fresh cassava root (FC) affected feed utilization, rumen metabolism, cyanide-using bacteria, and milk quality in lactating Thai Friesian dairy cows fed diets based on high sulfur-containing pellet (PS). Four lactating Thai Friesian dairy cows of 481.5 ± 31.3 kg BW (about 4 years old were allocated with four treatments in a 4 × 4 Latin square design. The four treatments were: replacement FC for CC at 0%, 60%, 80%, and 100% dry matter (DM), respectively. Feed intakes for four diets in terms of total dry matter intake (kg/day and % BW) was linearly correlated with levels of replacement of FC (p < 0.01). Digestibilities of crude protein (CP), DM, organic matter (OM), amylase-treated neutral detergent fiber (aNDF), and acid detergent fiber (ADF) did not change with increasing levels of FC in the diet (p > 0.05). Moreover, the total bacterial counts and cyanide population utilizing bacteria cubically increased with an increase of FC replacement (p < 0.01). The effect of CC substitution with FC in the PS diet was cubically increased on blood thiocyanate concentrations (p < 0.01). In addition, the propionate (C3) concentration at 0 and 4 h post-feeding changed significantly among treatments (p < 0.01), which were linearly improved with an increasing dose of replacement FC and were highest when FC was replaced at 100%. The yield of 3.5% fat-corrected milk was high in the treatment with the replacement of FC as compared to the control (p < 0.01). The yield of fat and milk fat percentages was high (p < 0.01) in the group with the replacement of FC as compared to feed with no diet replaced. The milk thiocyanate concentration was cubically enhanced when levels of FC replacement increased (p < 0.01) and was the highest when FC was replaced at 100%. As the amount of FC replacement was raised, the somatic cell count in the milk decreased linearly (p < 0.01). In conclusion, the replacement of FC at 100% in PS could enhance the feed intake, microbial populations, total volatile fatty acid (VFA), C3 concentration, milk yield, and milk quality.

Technical note: Effects of filter bags on neutral detergent fiber recovery and fiber digestion in vitro

Filter bags facilitate the measurement of amylase-treated neutral detergent fiber (aNDF) and in vitro (IV) undigested aNDF (uNDF) by eliminating the transfer of residues from beakers into filtration crucibles. The objectives of this study were to (1) determine effects of filter bags on recovery of aNDF and (2) evaluate effects of filter bags on IV uNDF. For study 1, 6 samples each of grass hay (GR), alfalfa (AL), and corn silage (CS) were selected. Large standard deviations (SD) of ash-free aNDF (aNDFom) for samples in each forage type indicated compositional diversity (15.1, 7.45, and 12.9% of DM for GR, AL, and CS, respectively), and starch SD for CS was 16.4% of DM. Samples were weighed into Berzelius beakers or filter bags [25-µm pores (F57) or 6-µm pores (F58); Ankom Technology, Macedon, NY] for measurement of aNDF and aNDFom. All samples were extracted with neutral detergent, thermostable α-amylase, and sodium sulfite, and then soaked in boiling water and then acetone. Residues from beakers were filtered through a sea sand-covered GF/D filter (Whatman, Marlborough, MA) in Gooch crucibles (CR). Filter bags were extracted in a pressurized chamber at 100°C. The aNDF values did not differ between F57 and CR, but F58 was greater than CR for CS and AL. For GR, F58 was greater than CR for aNDFom. For study 2, diverse samples with large SD of aNDFom (20.7, 7.45, and 12.9% of DM for GR, AL, and CS, respectively) were weighed as loose powder into medium bottles (LS) or F57 bags, which were weighted to prevent floating. Blended ruminal fluid from 3 steers fed a 30% aNDFom diet was used as inoculum. Three samples of 1 forage type were randomly assigned to 1 of 6 IV runs using both treatments (LS and F57), and 3 bottles of each sample-treatment combination were removed after 12 h and 2 were removed after 120 h to measure uNDF. For LS, residues were extracted as in study 1 for CR. For F57, bags were rinsed in cold water and extracted as described in study 1. After 12 h, uNDF of F57 was greater than LS in CS, AL, and overall types. Ash-free uNDF (uNDFom) after 12 h of F57 was greater than LS in CS and overall types. After 120 h, F57 was greater than LS for uNDF of CS, but no differences were detected for uNDFom. The SD of uNDFom, but not uNDF, was higher after 12 and 120 h for F57 compared with LS. From 6 to 96 h, overall gas production of F57 was less than LS, and F57 was less than LS for CS from 3 to 96 h. Overall, LS gave greater maximum and faster rates of gas production than F57, as did AL and CS, but lag did not vary. Results indicate that filter bags affected aNDF and aNDFom measurement and inhibited fermentation for some materials.

A low-fiber diet requires a longer adaptation period before collecting feces of pigs compared with a high-fiber diet in digestibility experiments using the inert marker method

The objective was to determine a minimum adaptation period in total tract digestibility experiments using the inert marker method for pigs fed a low- or high-fiber diet. Eight barrows with an initial body weight of 81.5 kg (standard deviation = 5.1) were assigned to 2 dietary treatments in a crossover design. A low-fiber diet was formulated based on ground corn, cornstarch, and soybean meal to contain 50 g/kg amylase-treated neutral detergent fiber. A high-fiber diet was prepared based on ground corn, corn distillers dried grains with solubles, and corn cobs to contain 296 g/kg amylase-treated neutral detergent fiber. In both diets, chromic oxide was included at 5 g/kg as an indigestible inert marker. Daily feed allowance was approximately 2.4% of initial body weight. Equal meals were provided at 0800 and 1700 h. After feeding diets without supplemental chromium (Cr) for 4 days, experimental diets with supplemental Cr were provided to pigs for 8 days. Total fecal collection was conducted during the 8 days with 24-h intervals. Daily Cr concentrations in feces increased linearly and quadratically (P < 0.001) in both low- and high-fiber diet groups as the collection days passed. The break point for fecal Cr concentration in the low-fiber diet group and high-fiber diet group was day 5.46 (SE = 0.145, P < 0.001) and day 3.49 (SE = 0.098, P < 0.001), respectively, based on a one-slope broken-line analysis. Coefficient of apparent total tract digestibility values of energy and nutrients (dry matter, organic matter, and crude protein) on day 3 and day 4 were lower (P < 0.001) than those on day 6–8 in the low-fiber diet. In pigs fed the high-fiber diet, the coefficient of apparent total tract digestibility of energy and nutrients on day 3 was lower (P < 0.001) than those on day 4–8. In conclusion, the minimum adaption period to achieve a constant inert marker concentration in feces is longer in a low-fiber diet compared with a high-fiber diet. We suggest an adaptation period of at least 6 days before grab sampling of feces when dietary fiber concentration is low.

Effect of experimental design on responses to 2 concentrations of metabolizable protein in multiparous dairy cows

The objective of this research was to characterize the implications of changing between diets formulated to be adequate (ADMP) or low (LOMP) in metabolizable protein in a Latin square (LSq) design or of feeding the same diets continuously in a randomized complete block experimental design (RCBD). Fifty-four multiparous early-lactation cows (initial average ± SD; parity 2.8 ± 0.9, 85.8 ± 31 d in milk, 715 ± 63 kg of body weight, 29.1 ± 2.7 kg of dry matter intake/d, and 57.7 ± 5.7 kg of milk yield/d) were blocked by parity and days in milk and were then randomly assigned to experimental design, with 16 cows assigned to LSq and 38 cows assigned to RCBD. Cows within blocks in LSq were randomly assigned to sequence in a 4-sequence, 4-period, 2-treatment LSq balanced for the effects of previous treatment carryover. Cows within blocks in RCBD were randomly assigned to dietary treatment, which was fed over the same four 28-d periods as the cows in LSq. Treatment diets were formulated to be similar in composition with the exception of exchanging an equal quantity of expeller soybean meal from ADMP (16.5% crude protein; 28.4% ash-free, amylase-treated neutral detergent fiber organic matter) for soybean hulls in LOMP (14.6% crude protein; 31.1% ash-free, amylase-treated neutral detergent fiber organic matter). Cows were individually fed treatment diets in a tiestall barn once daily for ad libitum consumption, milked 3 times daily, and administered recombinant bovine somatotropin every 14 d. Milk yield and feed offered and refused were measured daily; BW was recorded on 2 consecutive days each week; milk composition was measured at 6 consecutive milkings each week; and spot samples of feces, urine, and blood were collected during the last week of each period and a covariate period. Experimental designs were analyzed separately using results from wk 4 of each period with mixed effects modeling. Dry matter intake and milk fat yield were not affected by diet in either design, whereas milk and protein yields were greater for cows fed ADMP in both designs. Milk fat and protein percentage responses and milk energy output inferences were different between designs. Milk fat yield and percentage responses were affected by previous treatment carryover in LSq. Metabolic and digestibility inferences were very similar between designs. Under the conditions of this experiment, inferences on N metabolism and the majority of production measurements were not affected by experimental design, with the principal exceptions of milk fat and protein percentage and milk energy output.

Variation for in vivo digestibility in two maize hybrid silages

The experiment was aimed at confirming that silages made of two very similar hybrids could have different in vivo digestibility, primarily amylase-treated neutral detergent fibre digestibility (aNDFD), which could strongly influence the result of the calculation of energy value of fodder. Both the stay-green whole-plant types were grown at the same locality during two years and harvested at the same days at two-thirds milk line maturity. In the two subsequent years, silages without preservatives were made of both hybrids tested. All silages were fermented for 90 days. The in vivo digestibility of silages was measured in digestion trials with six sheep. All silages had good fermentation quality, and no differences in that regard were found between hybrids or years (P &amp;gt; 0.05). Hybrid had stronger effect than year on all indicators of chemical composition and digestibility of nutrients other than dry matter (DM). Hybrid significantly affected all indicators measuring chemical composition and digestibility of nutrients other than DM (P = 0.18). The aNDFD was closely correlated with all other measures of nutrients digestibility (P &amp;lt; 0.01). The results confirm the importance of breeding hybrids and analyzing silages for aNDFD.

Effects of whey, molasses and exogenous enzymes on the ensiling characteristics, nutrient composition and aerobic stability of maize cobs

The study was conducted to assess the effects of whey, molasses and exogenous enzymes on fermentation, aerobic stability and nutrient composition of ensiled maize cobs. Five treatments were ensiled in 1.5 L anaerobic glass jars over 32 days, namely i) control (maize cobs without additives (CON); ii) maize cobs with sugarcane molasses only (MOL); iii) MOL and whey (MOW); iv) MOW and exogenous enzyme at 0.5 g/kg maize cob mixture (ENZ1) and v) MOW and exogenous enzyme at 1 g/kg maize cob mixture (ENZ2). There was a day effect on gross energy (GE) for CON, MOL, ENZ1 and ENZ2 and none for MOW. There was a day effect in ADF for MOL, ENZ1 and ENZ2 and none for CON and MOW. There was lower dry matter (DM) on day 32 compared with day 0 for all treatments. There were treatment effects for GE, crude protein (CP), ash, ether extract, amylase-treated neutral detergent fibre and acid detergent fibre (ADF). On day 32, the neutral detergent fibre (NDF) and ADF concentrations in CON were higher than in MOL, MOW and ENZ2. At day 32, CON silage pH (4.2) was lower than the pH values of ENZ1 (4.5) and ENZ2 (4.6) silages. Acetic acid levels were higher in ENZ1 than ENZ2 silages. Ammonia nitrogen (NH3-N) levels averaged 25 ± 6.6 g NH3-N/kg total nitrogen, which is indicative of satisfactory ensiling. The MOL, ENZ1 and ENZ2 silages produced more carbon dioxide than CON and MOW silages. The addition of molasses and whey did not improve the nutritive quality of the maize cobs after ensiling. Ensiling maize cobs with molasses, whey and exogenous enzymes resulted in lower DM and fibre levels in the maize cobs, which could enhance intake and digestibility of nutrients when offered to pigs as a component of a balanced diet. Further investigations using higher concentrations of whey and molasses are warranted to improve the energy and protein composition of the maize cobs.

Short communication: The effect of an exogenous enzyme with amylolytic activity on gas production and in vitro rumen starch degradability of small and large particles of corn or barley meals

The objective of this study was to evaluate the effect of exogenous amylase supplementation on gas production and on in vitro rumen starch degradability (IVSD) of different sized particles of corn and barley meals (Cm and Bm, respectively). An aqueous liquid amylase formulation from Bacillus licheniformis was tested at 3 enzyme doses (EnzD; 0, 300 and 1,500 kilo novo units/kg of dry matter) on small (<750 µm) and large (≥750 µm) particle size (PS) of Cm and Bm. Data were analyzed according to a randomized complete block design with a factorial arrangement of treatments; the main tested effects were PS, EnzD, and their interaction. Fermentation run entered in the model as random effect. The mixed rumen fluid was collected from 2 rumen-fistulated Holstein dry dairy cows fed at maintenance (forage:concentrate ratio of 80:20; 12% crude protein; 55% amylase-treated neutral detergent fiber). Small particles of both Cm and Bm had a greater rate of fermentation and shorter lag time than large particles. The rate of starch degradation was greater for small than for large particles of Bm, being 0.187 and 0.125 1/h, respectively. Conversely, the rate of starch degradation of Cm averaged 0.063 1/h and was similar among treatments. Enzyme supplementation tended to reduce lag time and to increase rate of fermentation for both PS of Cm and Bm, with a more pronounced effect for small PS. A limited EnzD effect was measured for IVSD data and rate of starch degradation; PS influenced fermentation parameters and the magnitude of starch degradation more than EnzD. Supplementation with exogenous amylase influenced the rumen fermentation pattern of small and large PS of Cm and Bm, even if the effect of the enzyme supplementation differed according to the PS of cereal meals.

Variability in feed and total mixed ration neutral detergent fiber and crude protein analyses among commercial laboratories

The objective of this study was to assess the variability in amylase-treated neutral detergent fiber (aNDF) and crude protein (CP) analyses of feed and total mixed ration (TMR) samples among feed analysis laboratories. Two TMR were prepared that varied in the dry matter proportion of forage and concentrates: 45% forage (LF-TMR) versus 60% forage (HF-TMR). Replicated TMR and individual feed samples were dried, ground through a 4-mm screen, and sent to 10 commercial and 4 research or development laboratories for aNDF and CP analyses. Laboratories were asked to complete a detailed questionnaire regarding the aNDF procedure used. Variability in aNDF and CP analyses was assessed using univariate statistics and mixed modeling procedures. Significant variability in the aNDF analysis of individual feeds was found among the participating laboratories. The variability was particularly large for low-aNDF feeds such as distillers and barley grains. The variability among laboratories in the aNDF analysis of low-fiber TMR was greater than of high-fiber TMR, with the most likely reason being their greater proportions of grains and protein concentrates and the effect of variation in the aNDF protocols, particularly α-amylase use, on the analysis of these types of feeds. Variability due to the technique used for aNDF analysis was not statistically significant when outlier labs using the filter bag technique were removed; however, laboratories using the filter bag technique tended to produce more variable results than did laboratories using variation of the crucible technique (SE=2.542 vs. 0.930, respectively). Calculated aNDF values for TMR, based on proportions and aNDF analysis of individual feeds, were slightly greater than analyzed aNDF values for TMR. Results from this ringtest emphasize the need for feed analysis laboratories to follow the official aNDF method exactly. Variation within and among laboratories can be reduced by replicating analysis and including reference materials in each analytical run. Results of CP analysis were more consistent among laboratories, and variability in CP analysis of individual feeds or TMR was marginally acceptable.

Effects of isovalerate on ruminal fermentation, urinary excretion of purine derivatives and digestibility in steers

The objective of this study was to evaluate the effects of isovalerate supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers were used in a replicated 4 · 4 Latin square experiment. The treatments were: control (without isovalerate), low isovalerate (LIV), medium isovalerate (MIV) and high isovalerate (HIV) dosage of isovalerate at 100, 200 and 300 mg isovalerate per kg dry matter (DM) intake respectively. Diets consisted of corn stover and concentrate (60/40, DM basis). Dry matter intake was approximately 9 kg per day that was 90% of ad libitum intake including 5.4 kg corn stover and 3.6 kg concentrate. Ruminal pH (6.72–6.54) was linearly (p < 0.03) reduced, whereas total volatile fatty acid concentration (64.6–74.7 mmol/l) was linearly (p < 0.01) and quadratically (p < 0.01) increased with increasing isovalerate supplementation. Ratio of acetate to propionate increased linearly (p < 0.01) from 2.78 to 3.39 as isovalerate supplementation increased because of the increase in acetate production and decrease in propionate production. In situ ruminal degradation of amylase-treated neutral detergent fibre (aNDF) of corn stover was improved, but crude protein (CP) degradability of soybean meal decreased with increasing isovalerate supplementation. Urinary excretion of purine derivatives was quadratically (p < 0.01) changed by altering isovalerate supplementation (50.5, 54.3, 58.9 and 55.2 mmol/day for control, LIV, MIV and HIV, respectively). Similarly, digestibilities of organic matter, aNDF and CP in the total tract were linearly and quadratically increased with increasing isovalerate supplementation. The results of this study indicate that supplementation of diet with isovalerate improved ruminal fermentation and feed digestion in beef cattle. It was suggested that the isovalerate stimulated the digestive microorganisms or enzymes in a dose-dependent manner.

Measuring detergent fibre and insoluble protein in corn silage using crucibles or filter bags

Different methods exist for the determination of fibre concentration in feeds. To determine, whether fibre recovery and the contamination of fibre by nitrogenous compounds are altered, we measured fibre concentrations in a diverse set of corn silages using three method modifications and two extraction/filtration systems. Thirty-three corn silages, obtained from a commercial feed analysis laboratory, were dried (55°C for 24 h) and ground to pass through a 1-mm screen of a cutter mill before analysis. All samples were extracted in neutral detergent with the inclusion of sodium sulphite (neutral detergent fibre or NDF), α-amylase (neutral detergent residue or NDR) or both (amylase-treated neutral detergent fibre or aNDF), and using either Gooch crucible (CRUC) or filter bag (FBAG) systems. The aNDF method obtained the lowest and similar average fibre concentrations for both CRUC and FBAG (433 and 433 g/kg, respectively). Fibre concentration of NDR was greater (456 and 449 g/kg for CRUC and FBAG, respectively) than aNDF. Fibre concentration was greater for NDF (473 g/kg) than for NDR and aNDF (449 and 433 g/kg, respectively) when using FBAG. Poor extraction occurred for FBAG when α-amylase was not used. For CRUC, NDF and NDR concentrations were similar (456 g/kg), although filtration of fibre residue after extraction without α-amylase was difficult. Neutral detergent insoluble crude protein (ICP) was similar for NDF and aNDF, and slightly greater FBAG than for CRUC systems (8.4 and 9.6 g/kg, respectively). With both FBAG and CRUC, ICP was greater for NDR determined without sulphite (12.5 and 14.2 g/kg, respectively) than for aNDF (8.6 and 9.7 g/kg, respectively). The lower fibre concentration for aNDF method was attributed to less starch contamination when compared to NDF and to less protein contamination and possibly to extraction of phenolic compounds when compared to NDR. Concentration of acid detergent fibre (ADF) was greater for CRUC than for FBAG, although this difference was minimal (266 and 261 g/kg, respectively). Acid detergent ICP was similar for CRUC and FBAG systems and averaged 4 g/kg. We observed that amylase and sulphite affect the measurement of NDF concentration in corn silage. It is crucial that authors and laboratories accurately describe how they measure NDF and clearly indicate by acronym the method they used. Although the extraction/filtration system did not affect the determination of NDR and aNDF, the FBAG system generated higher NDF concentrations for corn silage when amylase is not used.

Effects of Sodium Sulfite on Recovery and Composition of Detergent Fiber and Lignin

Use of sodium sulfite to reduce nitrogenous contamination in fiber analysis was evaluated. The effects of sodium sulfite on analytical accuracy and precision were examined for amylase-treated neutral detergent fiber (aNDF), sequentially determined acid detergent fiber (sADF), and acid detergent lignin (sADL) in animal feeds. In one experiment, 0.5 g sodium sulfite was added per sample during neutral detergent (ND) extraction. The treatment consistently reduced aNDF, sADF, and sADL values of 180 alfalfa samples and improved precision (decreased within-sample variance of replicated analyses). The greatest effect was on precision of sADL analysis, with within-sample variance reduced by more than 50%. In a second experiment, 24 animal feeds were analyzed for a aNDF, sADF, and sADL with and without addition of 0.5 g sodium sulfite per sample during ND extraction. Nitrogen contents of the recovered fiber fractions were determined. Sodium sulfite reduced fiber and lignin values and decreased nitrogen concentration in residues. Within-sample variance was lower in all analyses. In a third experiment, 23 animal feeds were analyzed for aNDF with sodium sulfite at 0, 0.25, 0.5, and 1.0 g per sample. Average aNDF of feeds was reduced by each additional increment of sodium sulfite; however, 1.0 g sodium sulfite resulted in only a slight reduction in aNDF compared with 0.5 g. Therefore, 0.5 g sodium sulfite per sample should be added to samples prior to aNDF analysis.