RATE AND EXTENT OF DIGESTION OF COTTON THREAD AND OF DRY MATTER AND CELL WALL CONSTITUENTS OF SOYBEAN STOVER, ALFALFA AND THEIR BLENDS AND RUMEN CHARACTERISTICS OF SHEEP FED THESE FORAGES

1983 ◽  
Vol 63 (2) ◽  
pp. 373-380 ◽  
Author(s):  
R. SOOFI ◽  
G. C. FAHEY Jr. ◽  
L. L. BERGER
Keyword(s):  
Cell Wall ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Neutral Detergent Fiber ◽  
Nitrogen Recycling ◽  
Fiber Digestion ◽  
Cotton Thread ◽  
Dry Matter Digestibility ◽  
Expected Values

The rate and extent of digestion of cell wall fractions of soybean stover (SBS), alfalfa (ALF) and mixtures of these forages and the interactions (associative effects) between their components were measured using dacron bags in situ in eight mature sheep. The rate and extent of digestion of cotton thread was also compared to that of cellulose in intact plant cell walls. The extent of dry matter digestibility (DMD) of SBS, 2 SBS:1 ALF, 1 SBS:2 ALF and ALF was 48.1, 56.5, 66.8 and 73.3%, respectively. Neutral detergent fiber (NDF), acid detergent fiber (ADF) and cellulose digestibilities for the 2 SBS:1 ALF blend were 4.2, 4.1 and 4.3 percentage units lower, respectively, than expected values. Observed digestibilities for various components of the 1 SBS:2 ALF blend were not statistically different from expected values. Cotton fiber digestion in the rumen of sheep fed all ALF diets neared completion in 48 h (94.3%) and this value was significantly higher than those for sheep fed SBS (65.0%), 2 SBS:1 ALF (77.0%), and 1 SBS:2 ALF (88.5%). Rumen pH values, after feeding, tended to decline fastest in sheep fed ALF. Nitrogen recycling into the rumen occurred on all diets but was greater as quality of forage decreased. Molar concentrations of volatile fatty acids (VFA) increased after feeding in all instances. Key words: Sheep, soybean stover, alfalfa, associative effects, in situ dacron bag, cellulose digestion

EFFECT OF STRUCTURAL AND CHEMICAL FACTORS OF FORAGES ON POTENTIALLY DIGESTIBLE FIBER, INTAKE, AND TRUE DIGESTIBILITY BY RUMINANTS

1988 ◽  
Vol 68 (3) ◽  
pp. 787-799 ◽  
Author(s):  
V. GIRARD ◽  
G. DUPUIS
Keyword(s):  
Cell Wall ◽  
Dry Matter ◽  
Plant Cell Wall ◽  
Neutral Detergent Fiber ◽  
Optimum Number ◽  
Apparent Digestibility ◽  
Cool Season ◽  
Dry Matter Digestibility ◽  
True Digestibility

In view of the large variation found in plant cell wall digestibilities with ruminants, an attempt was made to group 124 feeds into different lignification classes (clusters) on the basis of chemical characteristics. Each feed cluster was described using a structural coefficient [Formula: see text] that related the potentially digestible fiber (PDF, %) to the ratio between lignin and cell wall volume. The optimum number of clusters was determined iteratively by performing a regression of the apparent digestibility of dry matter at maintenance level (DDM1, %) against the PDF and cell soluble (SOL, %) contents of feeds. The [Formula: see text] coefficients varied from 0.05 (grains, N = 13) to 1.85 (corn silage, N = 3) and increased with the maturity of the grasses from 0.88 (legumes, vegetative cool season grasses, N = 26) to 1.33 (mature, cool season grasses, N = 19). Predicted PDF were closely correlated (r > 0.9, P < 0.01) to in vitro cell wall disappearances (IVCWD). Apparently digestible cell wall in four grasses and four legumes increased linearly with 96-h IVCWD and standard error (SE) was similar to the SE of predicted apparent digestible SOL from SOL concentrations. Assuming that similarity between SE could be also observed in larger samples, PDF and SOL were used in summative equations to predict apparent dry matter digestibility. DDM1 discounted for intake (DDM1 – 4, %) was regressed against SOL and PDF concentrations of 87 feeds:[Formula: see text]with ds and df, the true digestibilities of SOL and PDF. Estimates of ds and df were 0.98 and 0.95 for a zero-production (maintenance) level of intake, and 0.91 and 0.79 for an intake level four times maintenance. Since the true digestibility of the PDF component was only 4% – 13% lower than that of the cell soluble component, the concentration of PDF in cell wall was the major determinant in the variation in apparent digestibility of forages. Key words: lignin, neutral detergent fiber, true digestibility, cluster analysis, feeds

scholarly journals THE EFFECT OF CONCENTRATE ON THE DIGESTION OF BROMEGRASS CONSTITUENTS

1981 ◽  
Vol 61 (4) ◽  
pp. 935-944 ◽  
Author(s):  
K. K. FRANKLIN ◽  
J. E. WINCH ◽  
G. K. MACLEOD
Keyword(s):  
Fatty Acids ◽  
Cell Wall ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Latin Square ◽  
Neutral Detergent Fiber ◽  
Total Volatile ◽  
Acid Detergent Fiber ◽  
Concentrate Supplementation ◽  
Wall Components

A nylon bag technique was used to study the effect of concentrate feeding on the rate and extent of digestion of bromegrass constituents in eight fistulated sheep fed rations at or slightly above maintenance, at concentrate to bromegrass ratios of 3:97, 22:78, 44:56 and 66:34. The eight sheep were arranged in a double 4 × 4 latin square design with nylon bag incubation times of 3, 6, 12, 24 and 48 h. Rations containing 44 and 66% concentrate depressed rumen digestion of bromegrass dry matter at both 24- and 48-h incubation times. The extent of digestion depression varied among sheep and was related to the animal's ability to buffer increases in rumen acidity. Digestibilities of neutral detergent fiber, acid detergent fiber, cellulose and hemicellulose followed trends similar to that of dry matter. Rumen osmolality, total volatile fatty acids and ammonia levels appeared to have little relationship to bromegrass dry matter digestion. The apparent or total gut digestibility of cell wall components was not depressed. This suggested that additional digestion took place in the ileum, cecum and colon and that the proportion of concentrate supplementation may affect ruminal but not the total gut utilization of roughage at maintenance levels of intake.

scholarly journals Cell wall components and in vitro dry matter digestibility of ensiled pea: Oat mixtures

2020 ◽  
Vol 36 (4) ◽  
pp. 477-485
Author(s):  
Jordan Markovic ◽  
Snezana Andjelkovic ◽  
Vladimir Zornic ◽  
Ivica Kostic ◽  
Milomir Blagojevic ◽  
...  
Keyword(s):  
Cell Wall ◽  
Dry Matter ◽  
Neutral Detergent Fiber ◽  
Seeding Rate ◽  
Forage Crops ◽  
Dry Matter Digestibility ◽  
Forage Intake ◽  
Forage Utilization ◽  
Wall Components

Cell wall content generally is regarded as the most important factor affecting forage utilization because it comprises the major fraction of forage dry matter and is correlated with forage intake and digestibility. The experiment was carried out to evaluate the cell wall constituents of ensiled pea - oat mixtures sown at five different seeding rates. Three effects were studied: application of bacterial inoculant, seeding rate of pea and oat in the mixtures and stages of plant development. The NDF (Neutral Detergent Fiber), ADF (Acid Detergent Fiber), hemicellulose, lignin and DMD (Dry Matter Digestibility) were determined in silages. Pea and oat were grown in binary mixtures at the experimental field of the Institute for forage crops, Krusevac - Serbia, and were tested at five different mixture rates: pure pea and pure oat crop, 25% pea + 75% oat, 50% pea + 50% oat, 75% pea + 25% oat. Application of bacterial inoculant affected lower content of NDF and hemicellulose (P< 0.05). Content of cell wall constituents decreased with increasing pea content in the mixtures, but DMD increased. On the other hand, content of cell wall constituents increased with plant growth and development, but DMD decreased.

USING A CELLULOLYTIC COMPLEX TO ESTIMATE IN VITRO DIGESTIBILITY OF BIRDSFOOT TREFOIL

1990 ◽  
Vol 70 (2) ◽  
pp. 487-493 ◽  
Author(s):  
D. K. DAVIS ◽  
R. L. McGRAW ◽  
D. A. SLEPER ◽  
P. R. BEUSELINCK
Keyword(s):  
Dry Matter ◽  
Lotus Corniculatus ◽  
Neutral Detergent Fiber ◽  
Birdsfoot Trefoil ◽  
In Vitro Digestibility ◽  
Detergent Solution ◽  
Two Stage ◽  
Fiber Digestion ◽  
Dry Matter Digestibility

Digesting forages with a prepared cellulase solution (PCS) has been shown to be a rapid method of obtaining dry matter digestibility (DMD) estimates in many species. This procedure has not been previously used to obtain DMD estimates of broadleaf birdsfoot trefoil (Lotus corniculatus L.). A broad based population consisting of 19 accessions, representing 11 countries of origin, three germplasm pools, and two domesticated cultivars of birdsfoot trefoil was evaluated. The PCS was produced from culturing Trichoderma reesei Simmons culture number QM9414. Fiber and PCS determinations were compared to an in vitro rumen fermentation (IVDMD) procedure. The fiber components measured were; neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose (HEMI). The PCS procedures involved digestion using a PCS without any pre- or post-treatment (CS), acid-pepsin digestion followed by a single-stage digestion in PCS (APCS), acid detergent solution (ADS) followed by a two-stage digestion in PCS (ADSCS), and neutral detergent solution (NDS) followed by a two-stage digestion in PCS (NDSCS). All of the fiber and PCS procedures were significantly (P ≤ 0.001) correlated with IVDMD except HEMI. The CS procedure underestimated IVDMD by 199 g kg−1; however, it had the best regression coefficient (b = 0.99), had the second best correlation coefficient (r = 0.86), and required less time than the other PCS procedures. The APCS procedure provided the best estimate of IVDMD. It overestimated the IVDMD mean of birdsfoot trefoil by only 30 g kg−1 and was the most accurate (residual standard deviation (RSD) = 22 g kg−1) approach. The CS procedure is recommended when a ranking of samples is desired and actual values of DMD are not of primary interest.Key words: Fiber digestion, germplasm, in vitro dry matter digestibility, Lotus corniculatus L., Trichodenna reesei Simmons

scholarly journals Application of Selected Inoculant Producing Antifungal and Fibrinolytic Substances on Rye Silage with Different Wilting Time

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 879
Author(s):  
Seong-Shin Lee ◽  
Jeong-Seok Choi ◽  
Dimas Hand Vidya Paradhipta ◽  
Young-Ho Joo ◽  
Hyuk-Jun Lee ◽  
...  
Keyword(s):  
Lactobacillus Plantarum ◽  
Dry Matter ◽  
Lactobacillus Brevis ◽  
Neutral Detergent Fiber ◽  
Dry Matter Digestibility ◽  
Fiber Digestibility ◽  
Aerobic Stability ◽  
Commercial Inoculant

This research was conducted to determine the effects of selected inoculant on the silage with different wilting times. The ryes were unwilted or wilted for 12 h. Each rye forage was ensiled for 100 d in quadruplicate with commercial inoculant (Lactobacillus plantarum sp.; LPT) or selected inoculant (Lactobacillus brevis 100D8 and Leuconostoc holzapfelii 5H4 at 1:1 ratio; MIX). In vitro dry matter digestibility and in vitro neutral detergent fiber digestibility were highest in the unwilted MIX silages (p < 0.05), and the concentration of ruminal acetate was increased in MIX silages (p < 0.001; 61.4% vs. 60.3%) by the increase of neutral detergent fiber digestibility. The concentration of ruminal ammonia-N was increased in wilted silages (p < 0.001; 34.8% vs. 21.1%). The yeast count was lower in the MIX silages than in the LPT silages (p < 0.05) due to a higher concentration of acetate in MIX silages (p < 0.05). Aerobic stability was highest in the wilted MIX silages (p < 0.05). In conclusion, the MIX inoculation increased aerobic stability and improved fiber digestibility. As a result of the wilting process, ammonia-N in silage decreased but ruminal ammonia-N increased. Notably, the wilted silage with applied mixed inoculant had the highest aerobic stability.

scholarly journals Evaluation of the Nutrient Composition, In Vitro Fermentation Characteristics, and In Situ Degradability of Amaranthus caudatus, Amaranthus cruentus, and Amaranthus hypochondriacus in Cattle

Animals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 18
Author(s):  
Kim Margarette C. Nogoy ◽  
Jia Yu ◽  
Young Gyu Song ◽  
Shida Li ◽  
Jong-Wook Chung ◽  
...  
Keyword(s):  
Crude Protein ◽  
Dry Matter ◽  
Gas Production ◽  
Nutrient Composition ◽  
Neutral Detergent Fiber ◽  
Amaranthus Cruentus ◽  
Amaranthus Caudatus ◽  
Amaranthus Hypochondriacus

The amaranth plants showed high potential feed value as forage for ruminants. An in-depth study of this plant, particularly in cattle, will help extend its utilization as an alternative protein and fiber feed source in cattle feeding. In this study, the nutrient compositions of three different species of amaranth, Amaranthus caudatus L., Amaranthus cruentus L., and Amaranthus hypochondriacus L.—two varieties for each species, A.ca 74, A.ca 91, A.cu 62, A.cu 66, A. hy 30, and A. hy 48—were evaluated. The in vitro technique was used to evaluate the fermentation characteristics such as total gas production, total volatile fatty acids (VFA) concentration, pH, and ammonia concentration of the rumen fluid. Moreover, the effective degradabilities of dry matter (EDDM) and crude protein (EDCP) of the amaranth forages were determined through in situ bag technique. The amaranth forages: A. caudatus, A. cruentus, and A. hypochondriacus showed better nutritive value than the locally produced forages in Chungcheong province of Korea. The CP of the amaranth ranged from 11.95% to 14.19%, and the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents ranged from 45.53% to 70.88% and 34.17% to 49.83%, respectively. Among the amaranth varieties, A. hypochondriacus 48 showed the most excellent ruminant feed nutrient quality (CP, 14.19%; NDF, 45.53%; and ADF, 34.17%). The effective degradabilities of dry matter (EDDM; 33–56%) and crude protein EDCP (27–59%) of the amaranth were lower compared to other studies, which could be due to the maturity stage at which the forages were harvested. Nonetheless, A. hypochondriacus 48 showed the highest EDDM (56.73%) and EDCP (59.09%). The different amaranth species did not differ greatly in terms of total VFA concentration or molar proportions, total gas production, or ammonia-N concentration. The high nutrient composition, and highly effective degradability of dry matter and crude protein, coupled with the favorable fermentation characteristics, suggest that the amaranth forages showed good to excellent feed quality for cattle.

Ruminal degradation characteristics of corn and corn–sunflower intercropped silages prepared at two stages of maturity

1992 ◽  
Vol 72 (4) ◽  
pp. 881-889 ◽  
Author(s):  
Z. Mir ◽  
P. S. Mir ◽  
S. Bittman ◽  
L. J. Fisher
Keyword(s):  
Dry Matter ◽  
Degradation Rate ◽  
Soluble Fraction ◽  
Corn Silage ◽  
Neutral Detergent Fiber ◽  
Acid Detergent Fiber ◽  
Ruminal Degradation ◽  
Whole Plants ◽  
Two Stages

The degradation characteristics of dry matter (DM), protein, neutral detergent fiber (NDF) and acid detergent fiber (ADF) of corn–sunflower intercrop silage (CSS) and monoculture corn silage (CS) prepared from whole plants, harvested at two stages of maturity, were compared using eight mature rumen-cannulated steers. The degradation characteristics were determined by incubating the silages in nylon bags for up to 72 h in the rumen of animals fed the respective silages. The degradation characteristics determined for the silages were the soluble fraction, the insoluble but degradable fractions, the rate of degradation of the degradable fractions of silage DM and protein, and the in situ disappearance of NDF and ADF after 0.5 and 72 h of incubation. The rate of particulate passage from the rumen was determined using chromium-mordanted NDF of the four silages. Values were used to estimate effectively degraded DM and protein. The rates of DM and protein degradation were highest for late-cut CSS (6.3 and 6.0% h−1, respectively) and the least for late-cut CS (2.5 and 0.8% h−1, respectively). Averaged across stages of maturity, more (P < 0.05) DM and protein were effectively degraded with CSS (57.4 and 70.1%, respectively) than with CS (48.8 and 48.7%). Degradation of NDF in early-cut CSS was lower (P < 0.05) than in CS after 72 h of incubation. ADF disappearance from all of the silages after 72 h of incubation was similar. Ruminal degradation of DM and protein in CSS was greater than in CS, which may affect efficiency of utilization of CSS. Key words: Degradation rate, effective degradability, corn silage, intercropped corn–sunflower, steers

scholarly journals Production and quality of Tifton 85 pastures overseeded with black oat: effects of irrigation and nitrogen fertilization

2018 ◽  
Vol 39 (5) ◽  
pp. 2071
Author(s):  
João De Assis Farias Filho ◽  
Fabiana Luiza Matielo de Paula ◽  
Adalberto Luiz de Paula ◽  
Wagner Paris ◽  
Fabrício Ghinzelli ◽  
...  
Keyword(s):  
Nitrogen Fertilization ◽  
Dry Matter ◽  
Irrigation System ◽  
Neutral Detergent Fiber ◽  
Lower Percentage ◽  
Forage Production ◽  
Dry Matter Digestibility ◽  
Randomized Design ◽  
Dead Material

The objective of this work was to evaluate the effects of irrigation and nitrogen fertilization on the bromatological quality, forage production, and botanical and structural composition of Tifton 85 (Cynodon sp.) pastures overseeded with black oat (Avena strigosa). Four treatments were evaluated in a 2 × 2 factorial scheme (irrigated and non-irrigated × fertilized and non-fertilized), with three replicates, in a completely randomized design. In irrigated paddocks, the irrigation system was activated when the soil matric potential reached a value equal to, or higher than, 10 kPa and 135 kg N ha-1 was applied to fertilized paddocks, divided into four applications. The forage mass pre- and post-grazing, total forage production, and the botanical, structural, and bromatological composition of the pastures were evaluated. No interaction was observed between the irrigation and nitrogen fertilization factors for any of the variables and no significant differences were observed in forage mass between pre- and post-grazing or in Tifton leaf and stem percentages. Nitrogen fertilization had a significant effect on forage production, which was 2626.41 kg dry matter (DM) ha-1 higher in fertilized pastures than in unfertilized pastures. In addition, fertilization resulted in a lower percentage of dead material (6.66%), higher percentage of oat leaves (30.84%), higher leaf:stem ratio (1:45), higher crude protein content (24.13%), lower levels of neutral detergent fiber (NDF) (64.57%) and acid detergent fiber (ADF) (32.86%), and higher in vitro dry matter digestibility (73.01%) than in unfertilized pastures. The use of irrigation did not influence total forage production, however, it resulted in pastures with lower NDF (65.97%) and ADF (33.54%), and higher in vitro dry matter digestibility (73.48%) than unirrigated pastures. Nitrogen fertilization produced improvements in pasture structure, associated with higher dry matter yield and bromatological quality, while irrigation only produced pastures with lower fiber content and greater digestibility.

scholarly journals Dietary rambutan peel powder as a rumen modifier in beef cattle

2020 ◽  
Vol 33 (5) ◽  
pp. 763-769
Author(s):  
Thiwakorn Ampapon ◽  
Metha Wanapat
Keyword(s):  
Beef Cattle ◽  
Dry Matter ◽  
Volatile Fatty Acids ◽  
Latin Square ◽  
Neutral Detergent Fiber ◽  
Napier Grass ◽  
Feed Consumption ◽  
Ruminal Fermentation ◽  
Fruit Peel ◽  
Negative Effect

Objective: The experiment was conducted to study the effect of rambutan (Nephelium lappaceum) fruit peel powder (RP) on feed consumption, digestibility of nutrients, ruminal fermentation dynamics and microbial population in Thai breed cattle.Methods: Four, 2-year old (250±15 kg) beef bull crossbreds (75% Brahman×25% local breed) were allotted to experimental treatments using a 4×4 Latin square design. Four dietary supplementation treatments were imposed; non-supplementation (control, T1); supplementation of RP fed at 2% of dry matter intake (DMI) (low, T2); supplementation of RP fed at 4% of DMI (medium, T3) and supplementation of RP fed at 6% of DMI (high, T4). All cattle were given a concentrate supplement at 1% of body weight while Napier grass was provided as a free choice.Results: The findings revealed that RP supplementation did not negatively affect (p>0.05) DMI of Napier grass, while RP intake and total DMI were the greatest in the RP supplementation at 4% and 6% DMI. Nevertheless, the nutrients (dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber) digestibilities were not changed in the RP supplementation groups. Rumen fermentation parameters especially those of total volatile fatty acids, acetate and butyrate were not significantly changed. However, the propionate concentration was remarkably increased (p<0.05) in the RP supplementation. Notably, the ratio of acetate to propionate, the number of protozoa, as well as the methane estimation were significantly reduced in the RP supplemented groups (4% and 6% of DMI), while the counts of bacteria was not altered.Conclusion: Supplementation of RP (4% of DMI) improved rumen propionate production, reduced protozoal population and methane estimation (p<0.05) without a negative effect on feed consumption and nutrients total tract digestibilities in beef cattle. Using dietary rambutan fruit peel powder has potential promise as a rumen regulator.

scholarly journals Degradación microbiana in situ de tejidos foliares de gramíneas y leguminosas y su relación con indicadores de calidad nutricional

2005 ◽  
Vol 6 (1) ◽  
pp. 100
Author(s):  
Diego Chamorro ◽  
Juan Evangelista Carulla ◽  
Pablo Cuesta
Keyword(s):  
Nutritional Quality ◽  
Dry Matter ◽  
Neutral Detergent Fiber ◽  
Dry Matter Degradation ◽  
Leaf Tissues ◽  
Dry Seasons ◽  
Stylosanthes Scabra ◽  
Negative Relationships

<p>Para cuantificar la degradación <em>in situ </em>de tejidos vegetales y su relación con la composición química de especies forrajeras se seleccionaron láminas foliares de las gramíneas <em>Bouteloua repens </em>y <em>Bothriochloa pertusa </em>y foliolos de las leguminosas <em>Stylosanthes scabra</em>, <em>Desmodium barbatum </em>y <em>Tephrosia cinerea</em>. En el rumen se incuba­ron muestras de 10 mm de largo durante 0, 12, 24, 48 y 72 horas; para la lectura del área residual se digitalizaron ocho tejidos. A las 24 y 48 h de incubación <em>B. pertusa </em>presentó relaciones positivas entre la degradación de la epidermis adaxial (EA) y la FDN (R2= 90,2), entre el mesófilo y la DIVMS (R2=80,1), y entre los tejidos len­tamente degradables (TLD) y la FDA (R2= 83,9); y relaciones negativas entre EA y DIVMS (R2= –73,1), los TLD con la DEF (R2= –74,3), la EA con la PC (R2= –87,6), y el esclerenquima con la DIVMS y la PC (R2= –84,3 y R2= –90,8). Después de 72 horas de incubación las mayores áreas residuales en gramíneas fueron la estructura kranz entre 34,2% y 36,5%, el mesófilo entre 20,9% y 21,4%, el xilema de 11,5% a 17,1% y la EA entre 11,8% y 13,9%; no obstante el esclerénquima se relacionó estrechamente con indicadores de calidad nutricional. Las gramíneas obtuvieron mayores porcen­tajes de tejidos no degradables que las leguminosas; por lo tanto, la DIVMS y la DEF fueron menores. Entre las leguminosas, <em>S. scabra</em>, presentó la mayor digestibilidad de los tejidos rápidamente degradables, tanto en sequía como en lluvia; en la época seca se incrementó en 134,6% la degradación de estos tejidos. Adicionalmente, en esta especie el área residual de los taninos no presentó relación directa con la degra­dación del mesófilo. En leguminosas la tasa y extensión de la degradación de las epidermis se incrementaron marcadamente a mayor tiempo de incubación, presen­tándose diferencias entre especies, situación que no exhibieron las gramíneas. En <em>D. barbatum </em>la degradación de la EA se asoció con la DIVMS y la DEF, explicando en 77,4% y 72,95% estos porcentajes; de igual manera se reportaron relaciones negati­vas entre la degradabilidad de la epidermis y los porcentajes de FDN, FDA, lignina y taninos (R2= –0,76; R2= –0,79; R2= –0,53 y R2= –0,76, respectivamente).</p><p> </p><p><strong>Microbial <em>in situ </em>degradation of grasses and legumes leaf tissues and its realtionship with nutritional quality and precipitation</strong></p><p>A study was conducted to measure the <em>in situ </em>de- gradation of plant tissues and its relationship with forage chemical composition in leaves of the grasses <em>Bouteloua repens </em>and <em>Bothriochloa pertusa </em>and of the legumes <em>Stylosanthes scabra</em>, <em>Desmodium barbatum </em>and <em>Tephrosia cinerea</em>. Forage samples of 10 mm in length were incubated in the rumen for 0, 12, 24, 48 and 72 h and tissue residual area was determined by reading the residual area in eight digitalized leaf samples per forage. In <em>B. pertusa</em>, after 24 and 48 h of incubation there were positive relations between the degradation of adaxial epidermis (AE) and the neutral detergent fiber (NDF, R2 = 90.2), between mesophyll and in vitro dry matter degradability (IVDMD, R2 = 80,1), and between slowly degradable tissues (SDT) and the acid detergent fiber (ADF, R2 = 83.9); and negative relationships between AE and IVDMD (R2 = -73,1), between SDT and effective dry matter degradation (EDMD, R2 = -74,3), between AE and crude protein (CP, R2 = -87,6), and between sclerenchyma and IVDMD with CP (R2 = -84,3 and R2 = -90,8, respectively). After 72 h of incubation, the greater residual areas in grasses were the Kranz structure (34.2% to 36.5%), mesophyll (20.9% to 21.4%), xylem (11.5% to 17.1%) and AE (11.8% to 13.9%). The area of sclerenchyma was related close­ly to indicators of nutritional quality. Overall, the grasses had greater content of non-degradable tis­sues than the legumes; therefore, their IVDMD and EDMD were lower. Among the legumes, <em>S. scabra </em>showed the greater digestibility of rapidly degrada­ble tissues, both during the rainy and dry seasons. At the dry season, the degradation of these tissues increased by 134.6%. Additionally, in this legume, the content of tannins did not have a direct relation­ship with the degradation of mesophyll. The rate and extension of the degradation of epidermis in legumes, were noticeably increased with increasing length of incubation, existing differences between species, a situation which was not observed in the grasses. In <em>D. barbatum</em>, the degradation of the AE was positively associated with both the IVDMD and EDMD (R2 = 77,4% and 72,95%, respectively). On the other hand, the degradability of epidermis and the percentage of NDF had negative relations with ADF, lignin and tannins (R2 = -0,76; R2 = -0,79; R2 = -0,53 and R2 = -0,76, respectively).</p>

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