Nutritive value and anatomical characterization from Pennisetum purpureum genotypes

Abstract

The research submitted samples from stems and leaf blades from tree genotypes of Pennisetum purpureum called 93-32-02, 92-70-02, and 91-06-02 (EMBRAPA - Dairy cattle) and elephant grass cv. Napier (reference cultivar) to the chemical, anatomical evaluations, and in vitro dry matter digestibility (IVDMD) measurement. The anatomical characteristics of the stems and leaf blades, the chemical composition, and the IVDMD of these genotypes at 70 days of re-growth were correlated. Concerning IVDMD, the data highlighted differences, and the cultivar Napier presented the smallest value. Digital images obtained by light microscopy from cross-section reveal that all the stem and leaf blade have similar structural organization. Quantitative differences were verified mainly in the stem. The leaves displayed differences only in the mesophyll thickness. The genotypes showed higher potential in the rainy season since they had the largest IVDMD when compared to the cultivar Napier.

Effects of leaf and stem maturation on nutritional value in Megathyrsus maximus

“…The internal organization and proportion of the system tissues and cell types may influence the intake and the proportion of polysaccharides suitable for microbial attack within the rumen. Lista et al 6 and Batistoti et al 13 described similar associations. It is noteworthy that lignin delays the hydrolysis of epidermal cells and sclerenchyma and also prevents the digestion of vascular tissues.…”

“…However, DMD correlates negatively with NDF, ADF, vascular tissue, and sclerenchyma, as is mentioned in several reports of C4 species. [6][7][8] Brito et al 51 evaluated the anatomy of leaves at different insertion levels in plants of Brachiaria brizantha and Brachiaria humidicola at 70 days growth and found a larger area of lignified tissues related to lower digestibility. Moreover, Batistoti et al 13 showed that a high proportion of fiber was negatively correlated with dry matter digestibility.…”

“…Anatomically, grass leaf blades are characterized by vascular tissue (composed of xylem and phloem cells), ground or support tissue, which is often divided into sclerenchyma and parenchyma, and assimilatory tissue, represented by mesophyll cells. 6,7 Quantitative plant anatomy has become a significant tool for the evaluation of forage quality, used in many studies as a complement to evaluate the digestibility of leaf blades tissues. The digestion potential of forage tissues decreases in the following order in the ruminant: parenchyma > phloem > epidermis > bundle sheath > xylem and sclerenchyma.…”

“…Identifying the tropical grass varieties with the highest nutritional value is important for the purposes of plant breeding. 6,8 Several studies in forage grasses have shown that their anatomical characteristics and nutritional composition are associated with their nutritional quality, 6,9 as well as influencing digestibility. 10,11 Numerous authors have mentioned the complexity of digestibility studies, which involve factors such as genotype, plant age, positions of the shoots, types of tissues involved and climatic variables.…”

“…Forage quality is generally measured by its nutritional value, which is highly associated with leaf blade anatomy, chemical composition, the digestibility of its constituents, and its voluntary consumption by the animals. Anatomically, grass leaf blades are characterized by vascular tissue (composed of xylem and phloem cells), ground or support tissue, which is often divided into sclerenchyma and parenchyma, and assimilatory tissue, represented by mesophyll cells 6,7 …”