Prediction of the nutritional value of grass species in the semiarid region by repeatability analysis

Abstract

-The objective of this work was to estimate the repeatability (r) and the number of samples required to measure the nutritional value of four warm-season forage grasses growing in a semiarid region. The grasses evaluated were Urochloa mosambicensis, Cenchrus ciliaris, Digitaria pentzii, and Megathyrsus maximus. Evaluations occurred under two forage management conditions: stockpiling and grazing. Hand-plucked forage samples were analyzed for dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, and in vitro DM digestibility (IVDMD). Four methods were used to estimate r and the number of samples required: analysis of variance, method of principal components based on the covariance (PCCOV) and the correlation (PCCOR) matrices, and structural analysis (EVCOR). Species were compared by the probability of the difference using the t-test. The method PCCOV presents the highest coefficient of repeatability and, therefore, a lower number of samples required. Lignin is the trait that have the highest number of samples required. In terms of qualitative traits, D. pentzii and M. maximus show the best forage qualities among the species evaluated.Index terms: chemical composition, IVDMD, sampling, warm-season grasses. Predição do valor nutricional de gramíneas na região semiárida por meio da análise de repetibilidadeResumo -O objetivo deste trabalho foi estimar a repetibilidade (r) e o número de amostragens necessárias para mensurar o valor nutricional de quatro gramíneas forrageiras tropicais numa região semiárida. As gramíneas avaliadas foram Urochloa mosambicensis, Cenchrus ciliares, Digitaria pentzii e Megathyrsus maximus. As avaliações ocorreram sob duas condições de manejo da forragem: diferimento e pastejo. Amostras de forragem coletadas por pastejo simulado foram analisadas para matéria seca (MS), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), lignina e digestibilidade in vitro da MS (DIVMS). Para a análise de r e número de amostragens necessárias, utilizaram-se quatro métodos: análise de variância, componentes principais da matriz de covariância (CPCOV) e de correlação (CPCOR), e análise estrutural (AECOR). As espécies foram comparadas pela probabilidade da diferença, tendo-se utilizado o teste t. Para o método CPCOV, observa-se maior coeficiente de r, portanto, menor número de amostragens necessárias. A lignina é a característica que apresenta o maior número de amostragens necessárias. Em termos qualitativos, D. pentzii e M. maximus mostram melhores características entre as espécies forrageiras avaliadas.Termos para indexação: composição química, DIVMS, amostragem, gramíneas tropicais.

WITHDRAWN: Classification of Megathyrsus maximus Accessions Grown in The Colombian Dry Tropical Forest by Nutritional Assessment during contrasting seasons

“…Several factors such as management, regrowth age, fertilization, cut height, phenological aspects, growth under shade and seasons might have a signi cant effect in the nutritional value of forages (Van Soest, 1982Velásquez et al, 2010, Santiago-Hernández et al, 2016, Silva et al, 2017, Coêlho et al, 2018, Vasconcelos et al, 2019, Schnellmann et al, 2020and Tesk et al, 2020 which affects digestibility in animals (Valente et al, 2010). Variability in structural carbohydrates (NDF, ADF) composition of the M. maximus collection may be in uenced by characteristics related to accession own physiological and metabolic aspects as the conversion e ciency of nitrogen and the rate of owering (Costa et al, 2017) which might generate a wide range of available accessions and could be used in plant breeding programs (Deo et al, 2020) to generate or select materials with the best IVDMD (Barahona & Sánchez-Pinzón, 2005) Protein content reduction during low precipitation periods might be caused by the lack of production of new leaves and tillers during dry season.…”

“…This classi cation shows there are accessions that respond to face prolonged tropical dry periods and possibly promote a resilient quality. In addition, M. maximus show better performance than other forage species used for grazing under semiarid or dry tropical conditions (Coêlho et al, 2018) and the diversity of nutritional composition related to genetic aspects shows the species M maximus as promising for breeding programs.…”

Ranking Species for Veld Restoration in Semi-Arid Regions Using Agronomic, Morphological and Chemical Parameters of Selected Grass Species at Different Developmental Stages under Controlled Environment

“…Based on observation the low NDF content (493.82 g/kg DM) of D. glomerata may have been a result of its thin stems and the high number of leaves. Coêlho et al [70] also indicated that the stem diameter (thin) and the number of leaves (high number) can influence the low content of NDF.…”

Caracterización del pasto mombaza como materia prima para producir bioetanol

“…Los resultados obtenidos son similares a los obtenidos por Wongwatanapaiboon et al (2012), quienes reportaron 4.4% en pasto pangola (Digitaria decumbens), 5.6% en atratum (Paspalum atratum) y 4% en pasto guineo (Megathyrsus maximus). Coêlho et al (2018) reportaron 1, 1.3 y 1.9% en Megathyrsus maximus, Digitaria pentzii y Urochloa mosambicensis, respectivamente. Por otro lado, en maderas coníferas y latifoliadas la concentración de LDA es mayor que en pastos o herbáceas.…”