Leaf Neutral Detergent Fiber Research Articles

Species dominance rather than complementarity drives community digestibility and litter decomposition in species‐rich Mediterranean rangelands

AbstractQuestionsManagement practices in permanent grasslands affect plant community structure and thus resources for both the herbivore and the decomposer subsystems. While their effects on digestibility or litter decomposition had been studied separately, few, if any, studies have tested the responses simultaneously and the underlying relationships with community functional structure. We tested whether the mass ratio hypothesis or the niche complementarity hypothesis held in scaling up from species to community level.LocationDry calcareous rangelands of southern France on a limestone plateau.MethodsWe measured digestibility and litter decomposability of 24 communities in three management regimes representing an intensification gradient corresponding to a combination of increased fertility and grazing. Key structural leaf traits (e.g. leaf dry‐matter content, LDMC) and chemical traits (e.g. leaf nitrogen content, LNC, and leaf neutral detergent fiber, LNDF) were measured as well as communities’ mean (i.e. community‐weighted mean, CWM) and variance (i.e. community‐weighted variance, CWV).ResultsDigestibility and litter decomposability were higher in intensively grazed and fertilized than in lightly grazed and abandoned communities. Increased nutrient availability combined with more intense grazing induced an increase in CWM LNC and a decrease in CWM LDMC and CWM LNDF. Communities in these regimes were less functionally diverse, with lower CWV LDMC and lower CWV LNDF.ConclusionsThe close relationship between digestibility and decomposability was maintained at the community level. Relationships between CWM, community digestibility and decomposability were more consistent across the management regimes than relationships with CWV, supporting the dominance rather than the complementarity hypothesis.

Stem and leaf forage nutritive value and morphology of reduced lignin alfalfa

AbstractReduced lignin alfalfa (Medicago sativa L.) has the potential to improve alfalfa forage quality, yet forage morphology, biomass allocation, and stem and leaf forage nutritive value remains undetermined. The objectives of this study were to characterize changes in morphological development and forage nutritive value within stem and leaf fractions for reduced lignin alfalfa. Reduced lignin (‘54HVX41’) and reference (‘DKA43‐22RR’) alfalfa cultivars were sampled weekly from the mid‐vegetative stage through full flower during the seeding (2015) and first production (2016) year at two locations in Minnesota. Samples were staged to determine maturity, divided into stem and leaf fractions, weighed, and analyzed for forage nutritive value. Alfalfa cultivars were similar in stem and leaf yield, leaf to stem ratio (L/S), stem crude protein (CP), stem neutral detergent fiber (NDF), leaf CP, leaf NDF, leaf acid detergent lignin (ADL), and leaf NDF digestibility (NDFD). On average, reduced lignin alfalfa showed a 14% decrease in stem ADL and a 12% increase in stem NDFD compared to reference alfalfa. For both cultivars, increases in forage maturity increased stem and leaf yields and decreased L/S. Forage maturity also affected stem and leaf forage nutritive values; as maturity increased, NDF and ADL increased while CP and NDFD decreased. These results indicate that changes in forage nutritive value for reduced lignin alfalfa are largely a result of changes in ADL and NDFD within the stem fraction, and confirm that alfalfa forage nutritive value is negatively affected by forage maturity, particularly within the stem portion of the plant.

Forage accumulation, tillering and bromatological characteristics of Brachiaria grass under nitrogen fertilization

The objective of this study was to evaluate the influence of different nitrogen doses on the forage accumulation, tillering and chemical characteristics of Braquiaria grass ( Urochloa decumbens (Stapf) Webster cv. Basilisk). A randomized block design with four replications was used, and each plot (50 m²) was an experi­mental unit. The treatments consisted of four doses of N (100, 200, 300 and 400 kg ha -1 year -1 of N) and the con­trol treatment. There was an increase in whole-plant crude protein (CP) and in leaf crude protein (LCP) and a decrease in whole-plant neutral detergent fiber (NDF) and leaf neutral detergent fiber (LNDF). Total dry matter accumulation (TDMA) and dry matter accumulation rate (DMAR) increased linearly in response to the N doses applied. Nitrogen fertilization promotes benefits such as increased biomass accumulation and improved forage chemical composition and tillering in Brachiaria grass.

Evaluación forrajera de leguminosas tropicales: Composición química, degradabilidad in vitro y selectividad ingestiva por bovinos y caprinos.

Se realizaron tres ensayos para determinar sucesivamente la composición química, la degradabilidad in vitro y la selectividad ingestiva de las leguminosas tropicales (LT) Stylosanthes guianensis (Estilosantes; SG), Cajanus cajan (Gandul; CC) y Arachis glabrata (maní forrajero; AG). El análisis químico incluyó las fracciones: materia orgánica e inorgánica (MO, MI), proteína bruta (PB), fibra detergente neutro y ácido (FDN, FDA), hemicelulosa, celulosa, lignina y nitrógeno insoluble en detergente ácido (NIDA) en muestras de planta completa y de componentes botánicos (tallo y hoja) de cada LT. Se determinó la degradabilidad in vitro de materia seca aparente y verdadera (DIVMSA y DIVMSV) en muestras de cada forraje mediante incubación durante 48 h con inoculo ruminal bovino y caprino. En una prueba de cafetería durante un periodo de 1 h, se observó la selectividad ingestiva de las tres LT por bovinos y caprinos, expresada mediante una escala cualitativa: ninguna, baja, mediana o alta. Se utilizó un heno comercial de gramíneas (HG) como criterio comparativo. En composición química, AG presentó un menor (P < 0.05) contenido de MO y mayor de MI que CC, SG y HG (P < 0.05). En las tres LT, el contenido de PB fue mayor (P < 0.05) y el de FDN menor (P < 0.05) que en HG. Entre las LT, la concentración de PB fue mayor (P < 0.05) en AG que en SG o en CC, mientras el porcentaje de FDN fue similar entre especies. El contenido de FDA y celulosa fue menor (P < 0.05) en AG que en CC o en SG, pero el contenido de hemicelulosa fue mayor (P < 0.05). El contenido de lignina fue menor (P < 0.05) en HG que en las LT, mientras que CC presentó la mayor (P < 0.05) concentración de NIDA entre los forrajes evaluados. El contenido de PB en las hojas de las tres LT fue mayor de 20%. El contenido de FDN fue menor (P < 0.05) en hojas de CC que en AG y SG, pero la FDA fue de mayor concentración (P < 0.05) en SG que en AG y CC. Las hojas de AG tuvieron mayores valores (P < 0.05) de hemicelulosa que CC y SG pero menores (P < 0.05) de celulosa. El contenido de lignina fue similar (P = 0.05) en las hojas de las tres LT, mientras las hojas de CC presentaron un mayor (P < 0.05) contenido de NIDA. El contenido proteico fue menor (P < 0.05) en tallos de CC que en los de AG y SG. El contenido de FDN y sus fracciones (FDA, hemicelulosa y celulosa) fue menor (P < 0.05) en los tallos de AG que en los de SG y CC. Los tallos de CC y AG presentaron los mayores contenidos de lignina y NIDA, respectivamente. Al usar ambos tipos de inóculos la DIVMSA y DIVMSV fue, en orden descendente, mayor (P < 0.05) en AG que en SG, HG y CC. En el ensayo de cafetería, AG y HG presentaron una mayor selectividad ingestiva por bovinos y caprinos que SG y CC. Estos resultados demuestran que AG tiene un mayor potencial forrajero que SG y CC basado en su contenido de nutrientes, degradabilidad in vitro y selectividad ingestiva. Sin embargo, las tres especies de LT tienen cualidades que las hacen alternativas interesantes para utilizarse como parte integral en sistemas de alimentación de rumiantes en el trópico.

Harvesting Interval Changes Yield and Nutritive Value of Kenaf in a Dry Tropical Climate

Kenaf (Hibiscus cannabinus L.) could be a forage alternative to the cattle production in the dry tropics of Mexico. The objective of this study was to evaluate harvest intervals on yield and nutritive value of kenaf ‘Everglades 41’. Intervals evaluated were 20, 40, and 60 d, and a single harvest in October when growth ceased. Since rainfall varied between 1998 and 1999, there was a year effect (P < 0.05) for yield and plant height. Total dry matter (DM) was lowest from the 20‐d harvest interval and highest from the October‐only harvest (P < 0.05) both years. Multiple harvest treatments resulted in greater leaf:stem ratios. The October‐only harvest had the lowest (P < 0.05) crude protein (CP) with 189 g kg−1 and the multiple harvest ranged from 237 to 286 g kg−1. Leaf neutral detergent fiber (NDF) increased, as harvest interval increased, from 148 g kg−1 DM in the 20‐d treatment up to 175 g kg−1 DM in the October‐only treatment. Stems harvested in October‐only had the greatest NDF. The lowest acid detergent fiber (ADF) concentration (P < 0.05) resulted from regrowth of 20‐d harvests, with 131 g kg−1 DM. October plant density was 27% lower (P < 0.05) at the 20‐d harvest interval than in October‐only harvest. A harvest interval of at least 40 d is required for kenaf persistence and vigorous recovery.

Leaf and stem nutritive value of timothy cultivars of different maturity at an irrigated site in southwestern Saskatchewan

Leaf and stem structural components contribute to variation in nutritive value among timothy (Phleum pratense L.) cultivars. Modelling timothy growth and nutritive value requires a better understanding of this variation. A trial of 11 timothy cultivars was conducted on irrigation at Swift Current, Saskatchewan from 1995 to 1997. Leaf:stem ratio, forage yield, days to maturity, N, P, acid detergent fiber (ADF) and neutral detergent fiber (NDF) concentrations, N/P ratio and P uptake of leaf and stem components were determined for spring growth forage. Two N fertilizer rates (100 and 150 kg N ha-1) did not consistently affect leaf and stem nutritive value. Cultivars differed in maturity, stem P, stem N, stem NDF, leaf NDF and leaf ADF in all 3 yr. Days to maturity was correlated to stem P concentration (r = 0.59, P < 0.05, to 0.77, P < 0.01) and leaf ADF concentration (r = 0.59, P < 0.05, to 0.82, P < 0.01) in all 3 yr but not to stem NDF concentration. Days to maturity was correlated to stem N concentration and leaf NDF concentration in 1995 and 1997 but not in 1996. However, days to maturity did not explain the observed variation among cultivars for stem NDF concentration and several other variables. While maturity differences among timothy cultivars must be taken into account when selecting for improved nutritive value or modelling growth and quality, additional variation for these traits was evident. Key words: Forage quality, Phleum pratense L., maturity, forage yield

Trends in Forage Yield and Nutritive Value of Hay‐Type Sorghum spp.

Sudangrass [Sorghum bicolor (L.) Moench], other Sorghum spp., and sorghum–sudangrass hybrids are used extensively for hay on U.S. cropland because of their production potential. Performance evaluations have emphasized yield and other agronomic characteristics but seldom emphasized forage quality. Available hay‐type sorghum cultivars released over a period of four decades were grown in five trials over a 21‐yr period to evaluate trends in forage yield and nutritive value. First‐cut (boot stage to head emergence) forage was harvested for yield and subsampled for one or more quality components. The first trial in 1977 tested forage crude protein (CP), and subsequent trials included more quality traits. In 1993 and 1998, the traits measured included leaf/stem ratio and leaf and stem concentrations of CP, neutral‐detergent fiber (NDF), and acid‐detergent fiber (ADF). Pearson correlation coefficients by year and correlations pooled across trials by two methods indicated similar relationships between forage characteristics and year of cultivar release. Year of release was positively associated with forage yield in two of the five trials and for the pooled correlations. Forage CP and CP of leaf and stem fractions were negatively correlated with year of cultivar release for the pooled trials and in most individual trials. Leaf NDF and ADF were positively correlated with year of cultivar release in the pooled trials. Yield gains of about 0.5% per year were found, but concomitant relative reductions of 0.1% or more per year in forage CP and leaf NDF run counter to the perceived need for improved hay quality. These findings emphasize the need to locate and incorporate cost‐effective sources of germplasm to enhance nutritive value of forage in hay‐type Sorghum spp.

Leaf Nutritive Value Related to Tiller Development in Warm-Season Grasses

Assessing nutritive value of key grass species in relation to plant development is essential for producers to efficiently manage livestock enterprises. Changes in nutritive value for tiller populations of 2 common Nebraska Sandhills grasses, prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.] and sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern], in response to morphological development was evaluated at the Gudmundsen Sandhills Laboratory (GSL) during the 1990 and 1991 growing seasons. Morphological development was determined on a 40 to 60-tiller sample from each block (12 blocks in 1990 and 8 blocks in 1991) at ten-day intervals using a comprehensive staging system. In vitro dry matter digestibility (IVDMD), crude protein (CP), neutral detergent fiber (NDF) and lignin were determined for leaves and correlated with the morphological index (Mean Stage by Count), growing degree days and day of the year. Leaf NDF values of both species remained constant while leaf IVDMD declined throughout the summer indicating that decline in leaf IVDMD was caused by declining cell wall digestibility. Leaf IVDMD was influenced more by tissue aging than advancing morphological stage. Leaf CP was significantly different between years but not between species indicating leaf CP was largely influenced by environmental factors. In both species and for both years, leaf CP initially declined rapidly to low levels and then stabilized during the vegetative phase. Nutritive value of a single vegetative morphological stage over the growing season was similar to the leaf tissue of the tiller populations. Management decisions by producers depend on accurate assessment of changes in nutritive value during the growing season in tiller populations of these 2 important grasses.

KUDZU IN THE SOUTH: AN OLD ALTERNATIVE CROP

Kudzu (Pueraria lobata) has become a pervasive weed in the southeast US. It has been receiving much attention recently and a study was initiated to evaluate the plant as an alternative food and feed source. Kudzu vines were sectioned into; 0-25, 25-50, 50-75 and 75-100 cm and analysed for acid detergent fiber (ADF), neutral detergent fiber (NDF), ash and crude protein content. Leaf ash content of kudzu increased while stem ash content decreased as the vine was sampled from the growing tip. Stem NDF increased from 44.4% at the 0-25 cm section to 57.83% at the 75-100 cm section of the vine, while leaf NDF declined from 52.23 to 39.01% for the same sections. The trend was reversed for ADF in the kudzu leaf and stem. Crude protein content of kudzu ranged from 18.45% at the 0-25 cm section for leaves to 7.42% for stem sections at 75-100 cm. The high crude protein content of kudzu as well as its abundance in the Southeast makes it a good feed source and a potential food source. However, further studies are needed to determine the vitamin content and digestion coefficient to ascertain its suitability as a food and feed source.