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D K Combs - One of the best experts on this subject based on the ideXlab platform.

  • Modification of a rumen fluid priming technique for measuring in vitro Neutral Detergent Fiber digestibility.
    Journal of dairy science, 2009
    Co-Authors: J.p. Goeser, P C Hoffman, D K Combs
    Abstract:

    Recently, we developed an alternate method to measure in vitro Neutral Detergent Fiber (NDF) digestibility (ivNDFD) based on a primed rumen fluid inoculum. Pretreating rumen fluid inoculum with cellulose and holding the inoculum until it generated 0.3 mL of gas/mL of rumen fluid before inoculating forage samples improved ivNDFD assay repeatability but depressed ivNDFD means. Our objective in this study was to determine if pretreating rumen fluid with a mixture of carbohydrates and urea would affect the ivNDFD mean and variance. We also used the modified procedure as a reference assay to calibrate near-infrared reflectance spectroscopy (NIRS) to predict 24-, 30-, and 48-h ivNDFD. Two experiments were completed. In experiment A, 3 ivNDFD assays modified from the method of Goering and Van Soest were evaluated over 24, 28, 48, 54, and 72 h by using dried, ground alfalfa (1 mm) or wheat straw (0.5 g) sealed in Ankom F57 forage Fiber bags. Bags were placed individually in 125-mL Erlenmeyer flasks and incubated with Goering and Van Soest media and 10 mL of rumen fluid. Rumen fluid was collected before feeding from 2 cannulated cows fed a high-forage diet and was prepared in 1 of 3 ways: 1) pooled rumen fluid was strained and used immediately to inoculate flasks (modified Goering and Van Soest method); 2) strained, pooled fluid was combined with buffer, reducing solution, and 1.25 mg of primer/mL of rumen fluid and allowed to produce 0.12 mL of gas/mL of rumen fluid before sample inoculation [Combs-Goeser (CG) method]; or 3) the CG method was used without the primer mixture (unprimed method). The assay was repeated 5 times, with 5 time points (24, 28, 48, 54, and 72 h) and 2 subsamples per time point for each method. Neutral Detergent Fiber was analyzed using an Ankom(200) forage Fiber analyzer and ivNDFD was determined as follows: ivNDFD (% of NDF) = 100 x [(NDF(0h) - NDF(residue))/(NDF(0h))]. Results were analyzed using a mixed model procedure, and data were blocked by method to obtain repetition sums of squares, which were compared by an F-test to assess interassay error. Repetition sums of squares were reduced with the CG method compared with the Goering and Van Soest method (19 vs. 228), and mean ivNDFD estimates were similar at 28, 48, and 54 h. In experiment B, 24-, 30-, and 48-h ivNDFD data for 54 feeds were determined in triplicate using the CG method, and corresponding samples were then scanned with an NIRS instrument. Calibrations were computed using partial least squares regression techniques. The NIRS calibration equation R(2) values were 0.93, 0.93, and 0.89 for 24-, 30-, and 48-h ivNDFD. Results suggest that the modified ivNDFD method using rumen fluid primed with a mixture of carbohydrate and urea (CG method) reduced interassay error.

  • An alternative method to assess 24-h ruminal in vitro Neutral Detergent Fiber digestibility.
    Journal of dairy science, 2009
    Co-Authors: J.p. Goeser, D K Combs
    Abstract:

    Abstract Interassay error caused by the inconsistent nature of rumen fluid inoculum confounds comparisons of forage in vitro Neutral Detergent Fiber (NDF) digestibility (NDFD) analyzed in different repetitions or laboratories. Our objective was to determine if priming rumen fluid and allowing it to produce a standard amount of gas before inoculating samples improved assay repeatability. In 2 experiments, we compared interassay error of NDFD estimates between several in vitro assays. In both experiments, dried, ground (1mm) alfalfa samples (0.5g) sealed in bags were placed in 125-mL Erlenmeyer flasks and incubated with in vitro media and 10mL of rumen fluid. In experiment A, rumen fluid was collected from a cannulated cow fed a high forage diet and prepared one of 2 ways; rumen fluid was either used immediately after it was collected and strained through cheese cloth (GVA), or strained fluid was combined with buffer, reducing solution, and 12.5mg of cellulose/mL of rumen fluid and allowed to produce a consistent amount of gas before inoculation (RPA). The assay was repeated 5 times, with 13 samples per method. In experiment B, inoculum was prepared one of 3 ways; RPA, GVA except rumen fluid was collected and pooled from 2 cows (GVB), or RPA with fluid pooled from 2 cows. The in vitro assays were repeated 5 times with 8 samples per method. Neutral Detergent Fiber was analyzed using a forage Fiber analyzer and 24-h NDFD was determined as: NDFD (% of NDF)=100×[(NDF 0h −NDF residue )/(NDF 0h )]. Data for each experiment were analyzed using a mixed model procedure and repetition sum of squares for each technique was determined and compared with an F-test to assess technique interassay error. In both experiments, rumen fluid priming significantly reduced repetition sums of squares, 51.2 versus 503 and 23.3 versus 164, compared with the respective GVA or GVB. However, priming significantly decreased NDFD values, 22.5 versus 24.8 and 23.9 versus 26.6%, compared with GVA and GVB, respectively. Priming rumen fluid with cellulose improved in vitro NDFD assay precision, but depressed in vitro NDFD.

  • Intake and milk production of cows fed diets that differed in dietary Neutral Detergent Fiber and Neutral Detergent Fiber digestibility
    Journal of Dairy Science, 2008
    Co-Authors: C. Kendall, Craig Leonardi, P C Hoffman, D K Combs
    Abstract:

    The objectives of this study were to determine how feeding diets that differed in dietary Neutral Detergent Fiber (NDF) concentration and in vitro NDF digestibility affects dry matter (DM) intake, ruminal fermentation, and milk production in early lactation dairy cows. Twelve rumen-cannulated, multiparous Holstein cows averaging 38 +/- 15 d (+/-standard deviation) in milk, and producing 40 +/- 9 kg of milk daily, were used in a replicated 4 x 4 Latin square design with 28-d periods. Treatment diets were arranged in a 2 x 2 factorial with 28 or 32% dietary NDF (DM basis) and 2 levels of straw NDF digestibility: 1) LD, untreated wheat straw (77% NDF, 41% NDF digestibility) or 2) HD, anhydrous NH(3)-treated wheat straw (76% NDF, 62% NDF digestibility). All 4 diets consisted of wheat straw, alfalfa silage, corn silage, and a concentrate mix of cracked corn grain, corn gluten meal, 48% soybean meal, and vitamins and minerals. Wheat straw comprised 8.5% DM of the 28% NDF diets and 16% DM of the 32% NDF diets. Cows fed 28% NDF and HD diets produced more milk, fat, and protein than those consuming 32% NDF or LD diets. Dry matter intake was greater for cows consuming 28% NDF diets, but intakes of DM and total NDF were not affected by in vitro NDF digestibility. Intake of digestible NDF was greater for cows consuming HD diets. Ruminal fermentation was not affected by feeding diets that differed in NDF digestibility. Ruminal NDF passage rate was slower for cows fed HD than LD. No interactions of dietary NDF concentration and in vitro NDF digestibility were observed for any parameter measured. Regardless of dietary NDF concentration, increased in vitro NDF digestibility improved intake and production in early lactation dairy cows.

Luiz Gustavo Nussio - One of the best experts on this subject based on the ideXlab platform.

  • exchanging physically effective Neutral Detergent Fiber does not affect chewing activity and performance of late lactation dairy cows fed corn and sugarcane silages
    Journal of Dairy Science, 2014
    Co-Authors: Sa A Neto, A W Ispo, Daniel Junges, A K Erch, Maity Zopollatto, J L P Daniel, Luiz Gustavo Nussio
    Abstract:

    Abstract The objective of this study was to determine whether replacing the physically effective Neutral Detergent Fiber (peNDF) of corn silage with sugarcane silage peNDF would affect performance in dairy cows. Twenty-four late-lactation Holstein cows were assigned to eight 3×3 Latin squares with 21-d periods. The dietary treatments were (1) 25% peNDF of corn silage, (2) 25% peNDF of sugarcane silage, and (3) 12.5% peNDF of corn silage + 12.5% peNDF of sugarcane silage. The physical effectiveness factors (pef) were assumed to be 1 for corn silage and 1.2 for sugarcane silage, as measured previously by bioassay. Thus, peNDF was calculated as Neutral Detergent Fiber (NDF) × pef. The concentrate ingredients were finely ground corn, soybean meal, pelleted citrus pulp, and mineral-vitamin premix. Dry matter intake (22.5±0.63kg/d), 3.5% fat-corrected milk yield (28.8±1.13kg/d), milk composition (fat, protein, lactose, urea, casein, free fatty acids, and somatic cell count), and blood metabolites (glucose, insulin, and nonesterified fatty acids) were unaffected by the treatments. The time spent eating, ruminating, or chewing was also similar among the diets, as was particle-sorting behavior. By contrast, chewing per kilogram of forage NDF intake was higher for the sugarcane silage (137min/kg) than the corn silage diet (116min/kg), indicating the greater physical effectiveness of sugarcane Fiber. Based on chewing behavior (min/d), the estimated pef of sugarcane silage NDF were 1.28 in the corn silage plus sugarcane silage diet and 1.29 in the sugarcane silage diet. Formulating dairy rations of equal peNDF content allows similar performance if corn and sugarcane silages are exchanged.

J.p. Goeser - One of the best experts on this subject based on the ideXlab platform.

  • An alternative method to assess 24-h ruminal in vitro Neutral Detergent Fiber digestibility.
    Journal of dairy science, 2009
    Co-Authors: J.p. Goeser, D K Combs
    Abstract:

    Abstract Interassay error caused by the inconsistent nature of rumen fluid inoculum confounds comparisons of forage in vitro Neutral Detergent Fiber (NDF) digestibility (NDFD) analyzed in different repetitions or laboratories. Our objective was to determine if priming rumen fluid and allowing it to produce a standard amount of gas before inoculating samples improved assay repeatability. In 2 experiments, we compared interassay error of NDFD estimates between several in vitro assays. In both experiments, dried, ground (1mm) alfalfa samples (0.5g) sealed in bags were placed in 125-mL Erlenmeyer flasks and incubated with in vitro media and 10mL of rumen fluid. In experiment A, rumen fluid was collected from a cannulated cow fed a high forage diet and prepared one of 2 ways; rumen fluid was either used immediately after it was collected and strained through cheese cloth (GVA), or strained fluid was combined with buffer, reducing solution, and 12.5mg of cellulose/mL of rumen fluid and allowed to produce a consistent amount of gas before inoculation (RPA). The assay was repeated 5 times, with 13 samples per method. In experiment B, inoculum was prepared one of 3 ways; RPA, GVA except rumen fluid was collected and pooled from 2 cows (GVB), or RPA with fluid pooled from 2 cows. The in vitro assays were repeated 5 times with 8 samples per method. Neutral Detergent Fiber was analyzed using a forage Fiber analyzer and 24-h NDFD was determined as: NDFD (% of NDF)=100×[(NDF 0h −NDF residue )/(NDF 0h )]. Data for each experiment were analyzed using a mixed model procedure and repetition sum of squares for each technique was determined and compared with an F-test to assess technique interassay error. In both experiments, rumen fluid priming significantly reduced repetition sums of squares, 51.2 versus 503 and 23.3 versus 164, compared with the respective GVA or GVB. However, priming significantly decreased NDFD values, 22.5 versus 24.8 and 23.9 versus 26.6%, compared with GVA and GVB, respectively. Priming rumen fluid with cellulose improved in vitro NDFD assay precision, but depressed in vitro NDFD.

  • Modification of a rumen fluid priming technique for measuring in vitro Neutral Detergent Fiber digestibility.
    Journal of dairy science, 2009
    Co-Authors: J.p. Goeser, P C Hoffman, D K Combs
    Abstract:

    Recently, we developed an alternate method to measure in vitro Neutral Detergent Fiber (NDF) digestibility (ivNDFD) based on a primed rumen fluid inoculum. Pretreating rumen fluid inoculum with cellulose and holding the inoculum until it generated 0.3 mL of gas/mL of rumen fluid before inoculating forage samples improved ivNDFD assay repeatability but depressed ivNDFD means. Our objective in this study was to determine if pretreating rumen fluid with a mixture of carbohydrates and urea would affect the ivNDFD mean and variance. We also used the modified procedure as a reference assay to calibrate near-infrared reflectance spectroscopy (NIRS) to predict 24-, 30-, and 48-h ivNDFD. Two experiments were completed. In experiment A, 3 ivNDFD assays modified from the method of Goering and Van Soest were evaluated over 24, 28, 48, 54, and 72 h by using dried, ground alfalfa (1 mm) or wheat straw (0.5 g) sealed in Ankom F57 forage Fiber bags. Bags were placed individually in 125-mL Erlenmeyer flasks and incubated with Goering and Van Soest media and 10 mL of rumen fluid. Rumen fluid was collected before feeding from 2 cannulated cows fed a high-forage diet and was prepared in 1 of 3 ways: 1) pooled rumen fluid was strained and used immediately to inoculate flasks (modified Goering and Van Soest method); 2) strained, pooled fluid was combined with buffer, reducing solution, and 1.25 mg of primer/mL of rumen fluid and allowed to produce 0.12 mL of gas/mL of rumen fluid before sample inoculation [Combs-Goeser (CG) method]; or 3) the CG method was used without the primer mixture (unprimed method). The assay was repeated 5 times, with 5 time points (24, 28, 48, 54, and 72 h) and 2 subsamples per time point for each method. Neutral Detergent Fiber was analyzed using an Ankom(200) forage Fiber analyzer and ivNDFD was determined as follows: ivNDFD (% of NDF) = 100 x [(NDF(0h) - NDF(residue))/(NDF(0h))]. Results were analyzed using a mixed model procedure, and data were blocked by method to obtain repetition sums of squares, which were compared by an F-test to assess interassay error. Repetition sums of squares were reduced with the CG method compared with the Goering and Van Soest method (19 vs. 228), and mean ivNDFD estimates were similar at 28, 48, and 54 h. In experiment B, 24-, 30-, and 48-h ivNDFD data for 54 feeds were determined in triplicate using the CG method, and corresponding samples were then scanned with an NIRS instrument. Calibrations were computed using partial least squares regression techniques. The NIRS calibration equation R(2) values were 0.93, 0.93, and 0.89 for 24-, 30-, and 48-h ivNDFD. Results suggest that the modified ivNDFD method using rumen fluid primed with a mixture of carbohydrate and urea (CG method) reduced interassay error.

Ellen Salah - One of the best experts on this subject based on the ideXlab platform.

Andrea Formigoni - One of the best experts on this subject based on the ideXlab platform.

  • effect of undigested Neutral Detergent Fiber content of alfalfa hay on lactating dairy cows feeding behavior Fiber digestibility and lactation performance
    Journal of Dairy Science, 2017
    Co-Authors: Mattia Fustini, A Palmonari, Giorgia Canestrari, Elena Bonfante, L Mammi, Maria Teresa Pacchioli, G C J Sniffen, R J Grant, K W Cotanch, Andrea Formigoni
    Abstract:

    The objective of this study was to investigate the effects of 2 alfalfa hays differing in undigested Neutral Detergent Fiber content and digestibility used as the main forage source in diets fed to high producing cows for Parmigiano-Reggiano cheese production. Diets were designed to have 2 different amounts of undigestible NDF [high (Hu) and low (Lu)], as determined by 240-h in vitro analysis (uNDF240). Alfalfa hay in vitro digestibility [% of amylase- and sodium sulfite-treated NDF with ash correction (aNDFom)] at 24 and 240 h was 40.2 and 31.2% and 53.6 and 45.7% for low- (LD) and high-digestibility (HD) hays, respectively. The 4 experimental diets (Hu-HD, Lu-HD, Hu-LD, and Lu-LD) contained 46.8, 36.8, 38.8, and 30.1% of alfalfa hay, respectively, 8.6% wheat straw, and 35.3% corn (50% flake and 50% meal; DM basis). Soy hulls and soybean meal were used to replace hay to balance protein and energy among diets. Eight multiparous Holstein cows (average milk production = 46.0 ± 5.2 kg/d, 101 ± 38 d in milk, and 662 ± 42 kg of average body weight) were assigned to a 4 × 4 Latin square design, with 2 wk of adaptation and a 1-wk collection period. Dry matter and water intake, rumination time, ruminal pH, and milk production and composition were measured. Diets and feces were analyzed for NDF on an organic matter basis (aNDFom), acid Detergent Fiber, acid Detergent lignin, and uNDF240 to estimate total-tract Fiber digestibility. Dry matter intake and rumination times were higher in HD diets compared with LD diets, regardless of forage amount. Rumination time was constant per unit of dry matter intake but differed when expressed as a function of uNDF240, aNDFom, or physically effective NDF intake. No differences were found among treatments on average ruminal pH, but the amount of time with pH <5.8 was lower in Hu-HD diets. Milk production and components were not different among diets. Total-tract aNDFom and potentially digestible Neutral Detergent Fiber fraction digestibility was higher for the LD diets (88.3 versus 85.8% aNDFom in HD), for which lower feed intakes were also observed. The Hu-HD diet allowed greater dry matter intake, longer rumination time, and higher ruminal pH, suggesting that the limiting factor for dry matter intake is Neutral Detergent Fiber digestibility and its relative rumen retention time.