DM Degradation Kinetics Research Articles

In situ rumen degradation of kernels from short-season corn silage hybrids as affected by processing.

The objective of this in situ study was to evaluate the rumen degradability of kernels from short-season corn hybrids grown for silage in Western Canada (Lacombe, AB) and determine whether decreasing kernel particle size would enhance ruminal degradability in a similar manner for all hybrids. The study was a completely randomized design with 3 beef cows (replicates) and a 6 (hybrid) × 3 (particle size) factorial arrangement of treatments. Kernels were processed to generate three different particle sizes: large (2.3 mm), medium (1.4 mm), and small (0.7 mm). Processed samples were incubated in the rumen for 0, 3, 6, 12, 24, and 48 h using the in situ method and degradation kinetics of DM and starch were determined. Effective rumen degradability (ED) was estimated using a passage rate of 0.04 (ED4), 0.06 (ED6), and 0.08/h (ED8). Hybrids exhibited a range in whole plant DM content (23.7 to 25.0%), starch content (15.9 to 28.1% DM), kernel hardness (21.9 to 34.4 s/20 g) and density (3.57 to 4.18 g/mL), and prolamin content (8.24 to 11.34 g/100 g starch). Differences in digestion kinetics among hybrids were generally more pronounced for starch than DM. The hybrids differed in starch degradability (P < 0.05), with earlier maturing hybrids having lower A fraction, lower k d, and lower ED, with hybrid effects on ED being accentuated with faster passage rate. Kernel DM content (r = -0.85, -0.87), hardness (r = -0.89, -0.86), and density (r = -0.84, -0.85) were negatively correlated with ED4 and ED8 of starch, respectively, due mainly to decreased k d of fraction B. Reducing the particle size of kernels increased ED of starch due to increased A fraction and k d of the B fraction. A tendency (P = 0.09) for hybrid × processing effects for ED6 and ED8 indicated that processing had greater effects on increasing ED of starch for earlier maturing hybrids. We conclude that short-season hybrids that mature early may have lower ED of DM and starch and would benefit from prolonged ensilage time. Kernel processing during silage making is recommended for short-season corn hybrids as a means of enhancing rumen availability of starch.

Yield survey and nutritional evaluation of garlic stalk for ruminant feed

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

608 Replacing corn grain by crude glycerol in diets of grazing dairy cows: Feed intake, pasture degradability, and milk production

Eighteen Holstein cows (6 ruminally cannulated) were used in the first 60 days of lactation to evaluate the effect of the replacement of corn grain (CG) by crude glycerol (CGly) on organic matter intake (OMI), pasture degradability and milk yield (MY). Cows were blocked [by parity (3.17±1.42), body condition score (3.0±0.3), expected caving date], and assigned randomly to two treatments (T). T1= partially mixed diet (PMR) containing sorghum silage (SS) plus concentrate (CG, wheat grain, soybean expeller, minerals and vitamins) and T2= PMR containing SS plus concentrate where CGly -76.5% glycerol, ALUR Uruguay- replacing the CG. Both groups received PMR in individual feeders and grazed during afternoon in a temperate pasture with herbage allowance-above the ground level- 60 kg DM.cow-1.day-1. Chemical composition of PMR (OM, CP, NDF, and EE in g/kgDM) respectively was for T1 [934, 117, 317, and 5] and [927, 106, 297 and 46] for T2. OMI and the ruminal degradation kinetics of DM of pasture were measured in situ in two periods. PMR intake (OMI-PMR) was measured individually as the difference between the amounts offered and refused. OMI-forage was determined with chromium oxide (Cr2O3) and indigestible acid detergent fiber as external and internal marker respectively. In situ data was fitted to nonlinear model D(t)=a+b(1-e-ct), where D= disappearance of DM , (a) soluble fraction, (b) degradable fraction, and (c) degradation rate. MY was Individual measured daily. Intake, degradability parameters, and MY were analyzed with a mixed model whit repeated measures. The model included fixed effects: T, period/week, interaction T*period and cow as a random effect. The statistical analyzes were performed with SAS (2010), data are expressed as lsmeans (s.e) and were considered to differ when P < 0.05. Treatment or interaction did not affect Total organic matter intake, OMI-PMR or OMI-f and was [23.6(1.4), 12.7(0.5) and 10.9 (1.0)] kgOM.d-1 for T1 and [20.8(1.3), 10.9(0.5) and 9.8 (0.9)] kg OM.d-1 for T2 respectively. The parameters “a”, “b” “c” of pasture were not affected by T, period or interactions and averaged 20(3.1) g/kgDM 602 (3.6) g/kgDM, 0.04(0.007) h-1. Milk yields was not affected by treatment (30.6(1.0) kg.día-1) or interaction T*week of lactation (WOL) but as expected it was affected for WOL. The absence of negative effects related to the use of CGly in substitution of CG in these conditions allows its use up to 10% DMI for dairy cows without altering the efficiency of the milk production process.

Technical note: A special apparatus for facilitating the in situ nylon bag measurement of the ruminal degradation of feedstuffs in cattle.

A new apparatus, named Bang-Bang (BB), which can facilitate the in situ nylon bag measurement of ruminal degradation in beef cattle, is described. The BB is an apparatus specially designed as a replacement of the traditional steel chain or flexible plastic tubes for binding the bags used in the in situ nylon bag (ISNB) method. The BB apparatus consists of cylindrical pedestals, sealing clips, nylon string, and nylon bags. A series of in situ rumen incubations using 3 ruminally cannulated beef steers were conducted to compare the BB with the ISNB method by measuring rumen DM degradation kinetics of 12 different feedstuffs commonly offered to beef cattle in China. Greater ( < 0.01) DM disappearance and less ( < 0.01) relative SD (%) were observed with the BB than with the ISNB method. In addition, effective degradability of DM was highly correlated between the 2 methods (ISNB = (1.01 ± 0.04 × BB) - 4.03 ± 2.12; = 0.99, < 0.001, = 12). These results indicate that the BB apparatus can be effectively used to determine the rumen degradation properties of feedstuffs with advantages over the traditional ISNB technique.

&lt;b&gt; &lt;i&gt;In situ&lt;/i&gt; degradability of dry matter and fibrous fraction of sorghum silage

This study aimed to evaluate in situ degradability and degradation kinetics of DM, NDF and ADF of silage, with or without tannin in the grains. Two isogenic lines of grain sorghum (CMS-XS 114 with tannin and CMS-XS 165 without tannin) and two sorghum hybrids (BR-700 dual purpose with tannin and BR-601 forage without tannin) were ensiled; dried and ground silage samples were placed in nylon bags and introduced through the fistulas. After incubation for 6, 12, 24, 48, 72 and 96 hours, bags were taken for subsequent analysis of fibrous fractions. The experimental design was completely randomized with 4 replicates and 4 treatments and means compared by Tukey’s test at 5% probability. As for the DM degradation rate, silage of CMSXS165without tannin was superior. Silages of genotypes BR700 and CMSXS 114 with tannin showed the highest values of indigestible ADF (59.54 and 43.09%). Regarding the NDF, the potential degradation of silage of CMSXS165 line without tannin was superior. Tannin can reduce ruminal degradability of the dry matter and fibrous fractions.

Effects of volume weight, processing method and processing index of barley grain on in situ digestibility of dry matter and starch in beef heifers

The objectives of this study were to evaluate the effects of volume weight (VW; g/L), processing method (PM; control vs. precision processing [PP]), and processing index (PI; VW after rolling/VW before rolling) of barley grain on in situ ruminal kinetics and in vitro intestinal digestion. The study was designed as a 2×2×2 factorial arrangement of treatments: VW (low vs. high), PM (control vs. PP) and PI (0.75 vs. 0.85). Ten barley samples, 5 low (580g/L) and 5 high (680g/L) VW, were either dry-rolled with a single roller setting (control) or screened into two fractions of small or large kernels using a 4-mm sieve, and then dry-rolled (i.e., PP). Each sample was dry-rolled moderately or coarsely with PI of 0.75 or 0.85. Three beef heifers (650±25.5kg body weight) fitted with rumen cannulas and fed a diet consisting of 700g/kg barley silage and 300g/kg concentrate mix (dry matter [DM] basis) were used for the in situ study. In situ degradation kinetics of DM and starch were estimated after 0, 3, 6, 12, 24 and 48h of ruminal incubation. Data from DM and starch degradation at different times of incubation were fitted to a model y=a+b(1−e−c(t−L)). in vitro intestinal disappearances of DM and starch of ruminal residue after 12h of incubation were determined using a modified three-step procedure. Interactions between VW and PM on effective degradability (ED; P<0.01) and between PM and PI on the degradation kinetics (P<0.05) were observed. The VW of barley grain did not affect the degradation kinetics of DM and starch whereas ED of DM was greater (P<0.01) in high versus low VW in the control samples. For in situ DM disappearance, a (P<0.01) and b (P<0.07) fractions were lower, but c and ED were higher (P<0.01) in PP versus control samples. Increased processing of barley consistently resulted in greater (P<0.01) values of degradation kinetics and ED compared with less processed barley. Intestinal DM disappearance of rumen residues was affected by all three factors (VW, PM and PI). Regression results showed that the rate of DM disappearance was correlated to the particle size distribution and the fine particles were the primary predictor. The results demonstrated that the PP approach and manipulating PI are effective ways to optimize rumen digestion of barley grain. This suggests that a concise and reliable method to predict rumen digestion of barley may be developed based on measuring the fines content of processed barley.

Nutritive value and in situ digestibility of pearl millet hay as affected by moisture concentration and bale sampling depth

Seven hectares (ha) of pearl millet [Pennisetum glaucum (L.) R. Br.] were divided into 3 blocks with 3 whole plots each to evaluate the effects of moisture (165, 187, and 274 g/kg of DM) and sampling depth (0.2, 0.4, and 0.6 m) in round bales on chemical composition and in situ disappearance. Plots were assigned randomly to moisture treatments. Round bales (n = 3 per plot; 1.2 × 1.5 m, 568 kg) were obtained and sampled at 3 different depths within each bale (n = 81) before and after 71 d of storage. Duplicate in situ bags (10 × 20 cm) were incubated in 6 ruminally cannulated cows (BW = 585 ± 37.8 kg) up to 120 h. Residual DM for each sampling time was fit to a nonlinear model using PROC NLIN of SAS to determine DM degradation kinetics. Data were analyzed as a split-plot design using Proc Mixed procedures of SAS and tested for moisture, depth, and their interactions. Bale temperature and concentrations of ADL were greater (P 0.10) any of the digestion variables, but the water-soluble fraction, potentially degradable fraction, and effective ruminal disappearance as well as concentrations of OM, NDF, and acid-detergent insoluble nitrogen were affected (P < 0.05) by the moisture × sampling depth interaction. Therefore, a greater range in sampling depth should be used to accurately assess heat damage in large round bales.

Degradation Characteristics of Legume Straw Based Complete Rations in the Rumen Using Nylon Bag Technique

A study was conducted to determine the chemical composition and nutrient degradability of legume straw based complete rations using nylon bag technique in buffalo bulls. Two iso-nitrogenous complete rations were prepared by incorporating two legume straws viz. red gram (T1) and black gram (T2) and concentrate mixture in 60: 40 proportion. The experiment was conducted using two rumen fistulated buffalo bulls, fed a basal diet comprising of 5 kg para grass, 4 kg paddy straw and 1.5 kg concentrate mixture. Feed samples were incubated in the ventral sac of rumen for 3, 6, 12, 24, 36, 48 and 72hr. In sacco degradation kinetics revealed that rapidly soluble fraction (a), slowly degradable fraction (b), potential degradation (a+b) and effective degradability of DM, NDF and ADF were significantly (P<0.01) higher in T2 compared to T1. Degradation kinetics of CP revealed that rate constant (c) was higher (P<0.05) in T1 while potential degradation (a+b) was higher (P<0.05) in T2 compared to other ration. Hence it can be concluded that black gram straw based complete ration have an advantage over red gram straw based complete ration due its higher degradation kinetics of DM, NDF and ADF in the rumen.

Ruminal and intestinal amino acid digestion of distiller's grain vary with grain source and milling process

A study was conducted to evaluate the in situ ruminal degradability of crude protein (CP), amino acid (AA) profiles of ruminal undegradable protein (RUP), and in vitro intestinal digestibility of AA for dried distillers grains with solubles (DDGS) as affected by grain source (corn vs. wheat) and milling process (conventional vs. fractional). The feeds tested included wheat, wheat DDGS (WDDGS), corn, corn DDGS (CDDGS) and corn fractional DDGS (FDDGS). The feeds were evaluated in three ruminally cannulated beef heifers fed a diet containing 600g/kg barley silage and 400g/kg barley-based concentrate (dry matter [DM] basis). Polyester bags containing 5g of ground feed (2-mm) were incubated in the rumen of each heifer for 0, 2, 4, 6, 12, 16, 24, and 48h. Ruminal microbes were labeled using 15N to correct the bacterial contamination. The model y=a+b(1−e−c(t−lag)) was fitted to determine degradation kinetics of DM and protein. Effective degradability (ED) was determined as: a+[bc/(c+k)], where k was assumed to be 0.06/h. In vitro intestinal digestibility of the RUP and AA were determined on the residue after 16h of ruminal incubation using a modified 3-step method. The CP, neutral detergent fiber, acid detergent fiber, ether extract, and mineral contents of DDGS varied (P<0.01) with grain and milling process. Amino acid profiles of DDGS were different (P<0.05) from those of the original grain. Ruminal degradation of CP was lower (P<0.01) in DDGS than in the original grain, and lower (P<0.01) in FDDGS than in CDDGS, with no difference between WDDGS and CDDGS. However, ruminal degradation of essential AA (EAA) was higher (P<0.05) for WDDGS than for CDDGS, and it was lowest (P<0.01) for FDDGS. The AA profiles of RUP were different (P<0.05) between DDGS and the original grain as well as between DDGS types. Intestinal digestibility widely varied among individual AA and among feeds. The intestinal digestibility of total AA and EAA was not different between WDDGS and CDDGS, but it was lower (P<0.05) for FDDGS than for CDDGS. Estimated intestinal absorbable total AA and EAA were highest (P<0.05) for FDDGS, intermediate (P<0.05) for CDDGS, and lowest (P<0.05) for WDDGS. The results suggest that the AA availability of DDGS varies with the grain source used to produce ethanol and with the milling process prior to ethanol fermentation. Although FDDGS is a good RUP source, its CP digestibility coefficient in the total digestive tract of cattle is lower (P<0.05) than that of WDDGS and CDDGS.

Effect of herbage depletion on short-term foraging dynamics and diet quality of steers grazing wheat pastures1

Two complementary experiments were completed to assess short-term foraging dynamics, diet quality, and ruminal degradation kinetics of herbage consumed by steers with 3 levels of herbage depletion. Experiment 1 was a behavioral study in which 2 ruminally cannulated steers were allocated to grazing scenarios simulating 3 levels of herbage depletion. These treatments included an ungrazed sward (control), as well as medium and high levels of herbage depletion. Grazing scenarios were sampled for sward surface height and amount of green leaf and stem before being grazed. Foraging dynamics were determined through measurements of bite rate, bite depth, eating step rate, eating distance, potential area consumed while grazing, and bites and intake per eating step. Also, quality of potential herbage consumed was estimated from hand-plucked herbage. In Exp. 2, ruminal degradation kinetics of DM for samples of herbage consumed (masticate) by steers during Exp. 1 were assessed in situ using 5 ruminally cannulated steers. The immediately soluble, degraded, and undegraded DM fractions were determined. The DM disappearance rate and lag times were determined from a nonlinear regression model, and the effective degradability of DM was calculated. Herbage depletion resulted in increased eating steps/minute, as well as the potential area harvested while grazing (P < 0.05) and reduced herbage intake/eating step (P < 0.05). Neither the herbage potentially consumed nor the ruminal degradation kinetics was affected by extent of depletion (P > 0.05). Under these experimental conditions, steers adapted their foraging dynamic and were able to sustain diet quality in the short term. These results imply that behavioral adaptations would make diet quality less sensitive to certain levels of herbage depletion.

Cinética ruminal da degradação de nutrientes da silagem de milho em ambiente ruminal inoculado com diferentes aditivos

Objetivou-se avaliar a cinética ruminal da degradação de MS, PB e FDN da silagem de milho em ambiente ruminal inoculado com diferentes aditivos. Utilizou-se um delineamento em quadrado latino 4 x 4, com quatro bovinos holandeses e quatro períodos de incubação, em ambiente ruminal adaptado ou não com diferentes aditivos alimentares. Foram testados os seguintes tratamentos: SCL - silagem de milho em ambiente ruminal sem inoculação de aditivo; SBL - silagem de milho em ambiente ruminal inoculado com 5 g de produto comercial contendo bactérias ruminais e intestinais liofilizadas (Ruminobacter amylophilum: 3,0 x 10(11) ufc/kg; Fibrobacter succinogenes: 3,0 x 10(11) ufc/kg; Succinovibrio dextrinsolvens: 4,4 x 10(11) ufc/kg; Bacillus cereus: 3,5 x 10(11) ufc/kg; Lactobacillus acidophilus: 3,5 x 10(11) ufc/kg e Streptococcus faecium: 3,5 x 10(11) ufc/kg); SEC - silagem de milho em ambiente ruminal inoculado com 15 g de produto comercial contendo enzimas celulolíticas (xilanase 10%); e SMS - silagem de milho em ambiente ruminal inoculado com 3 g de produto comercial contendo monensina sódica. Os tratamentos SBL e SEC não afetaram a fração potencialmente degradável (b) dos nutrientes avaliados da silagem de milho. A monensina sódica reduziu a fração (b) da MS (51,01%) e a degradabilidade potencial da silagem de milho (72,33%). Entre os aditivos estudados, a monensina sódica proporcionou a maior fração não-degradável da FDN (45,57%), reduzindo o desaparecimento desta fração a partir de 48 horas de incubação intra-ruminal. Os diferentes aditivos, nas concentrações estudadas, não proporcionaram melhora na degradabilidade efetiva da MS, PB e FDN da silagem de milho.

Effects of calendar date and summer management on the in situ dry matter and fiber degradation of stockpiled forage from bermudagrass pastures.

Limited information is available that describes the disappearance kinetics of bermudagrass (Cynodon dactylon L. Pers.) during fall and early winter. Five ruminally cannulated, crossbred steers (387 +/- 18.3 kg) were used to determine the effects of calendar date and previous summer management on the in situ degradation kinetics of DM and NDF for forage clipped from stockpiled 'Greenfield' bermudagrass pastures. Forage was stockpiled at two sites following summer hay or pasture management, and samples were taken outside (GRAZED) and under caged exclosures (UNGRAZED) at 4-wk intervals beginning October 17, 1997, and ending January 9, 1998. No effort was made to remove or avoid contaminate species. Concentrations of NDF increased (P < 0.001) to a maximum for UNGRAZED forages at the hay site between October 17 and December 12, but sampling date had no effect (P = 0.627) on concentrations of NDF at the pasture site. Concentrations of ADF and lignin increased (P < or = 0.023) during at least one sampling interval in UNGRAZED forages at both sites. At the hay site, degradation rates of DM decreased (P < 0.001) by 0.013/h for UNGRAZED forage between October 17 and January 9, whereas the effective ruminal degradability of DM decreased (P < 0.001) by 33.5% during the same time period. Fractional degradation rates of NDF for UNGRAZED forages at the hay site decreased (P < 0.001) by 0.014/h between October 17 and November 14 but did not change (P > or = 0.077) throughout the remainder of the study. The effective ruminal degradability of NDF decreased (P < 0.001) by 33.8% between the first and last sampling date. At the pasture site, sampling date did not affect (P = 0.458) rates of DM degradation, but the effective degradability of DM for UNGRAZED forages decreased (P = 0.001) by 19.0% from October 17 to December 12. Rates of NDF degradation for UNGRAZED forages did not differ (P > or = 0.113) on the first three sampling dates, but the rate on January 9 was slower than that observed on October 17 (P = 0.025) and November 14 (P = 0.044). The effective degradability of NDF decreased (P < 0.001) by 19.2% between October 17 and December 12. These data indicate that stockpiled bermudagrass should be used during a limited window during the late fall; after this time, the nutritive value becomes very poor.

Effect of Maturity on Degradation Kinetics of Sod-Seeded Cereal Grain Forage Grown in Northern Arkansas

Wheat (Triticum aestivum L.), oat (Avena sativa L.), and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested at 3-wk intervals throughout March, April, May, and early June. Plant growth stage was documented for each forage on each harvest date, and harvested forages were evaluated for forage quality characteristics. Degradation kinetics of DM and NDF for these forages were evaluated by the in situ method. Fractional degradation rates for DM and NDF in all three species were relatively rapid for vegetative forage (≥0.086h –1) but declined rapidly by the heading stage of development and stabilized thereafter. Forage quality declined and forages were more resistant to ruminal degradation as plants entered the reproductive stages of growth. Based on these findings, growth stage is an effective predictor of most characteristics of in situ DM and NDF disappearance. The relationships between these degradation parameters and growth stage were typically explained with quadratic or cubic models. Clearly, forage quality characteristics of overseeded rye deteriorated more rapidly with phenological development and growth stage than quality characteristics of overseeded wheat and oat grown in the same environment. For rye, this problem is further complicated by its accelerated phenological development. These factors combine to permit a very narrow harvest window in early spring, relative to the other cereal grains evaluated. Acceptable forage quality may persist for an extended period in wheat and oat; this suggests that producers wishing to utilize these forages may lengthen the harvest window by planting more than one species, either as a mixture or preferably in independent stands.