Amostras de quatro variedades de capim Elefante (Pennisetum purpureum Schum.), Cameron, Taiwan A-148, Vruckwona e Taiwan A-241, obtidas aos 37, 67 e 97 dias de crescimento vegetativo, foram analisadas quanto aos teores de matéria seca, componentes da parede celular e digestibilidade da matéria seca. Não houve diferenças entre as variedades estudadas nos teores de matéria seca, fibra em detergente neutro, fibra em detergente ácido, celulose e lignina. A variedade Taiwan A-148 apresentou teor menor de hemicelulose e sílica. Com o desenvolvimento vegetativo, aumentaram os teores de matéria seca (9,7 a 20,3%), celulose (33,4 a 40,6%) e lignina (4,8 a 7,3%) entre 37 e 97 dias, sendo o aumento da celulose e da lignina maior entre 37 e 67 dias; a matéria seca aumentou mais entre 67 e 97 dias. Não houve variação no teor de hemicelulose (23,2%) no período considerado. O teor de sílica diminuiu de 1,74 a 1,56% entre 37 e 67 dias, não tendo variado entre 67 e 97 dias. A digestibilidade da matéria seca foi reduzida de 78,1 a 50,5% nas amostras colhidas aos 37 e 97 dias, sendo a diminuição maior entre 37 e 67 dias (78,1 a 60,5%). Houve correlação negativa significativa entre os resultados do efeito da maturidade sobre a digestibilidade da matéria seca e as demais variáveis estudadas. Qualquer das variedades consideradas neste trabalho pode ser utilizada indiferentemente aos fins a que se destina, sob o ponto de vista dos parâmetros estudados.

Samples of four varieties - Cameron, Taiwan A-148, Vruckwona, and Taiwan A-241, of Elephant grass (Pennisetum purpureum Schum.) were collected from experimental plots after 37, 67 and 97 days’ growth and used for determinations of dry matter, main cell wall constituents, and digestibility of the former. There were no significant varietal differences for the parameters studied: dry matter content, neutral detergent fiber, acid detergent fiber, cellulose, and lignin. One exception was Taiwan A-148 that showed slightly lower contents of hemicellulose and silicon compounds than the other three varieties. Comparison of the samples for the three growing periods indicated that there was an increase in the percentage of dry matter (9.7% to 20.3%), cellulose (33.3% to 40.6%), and lignin (4.8% to 7.3%) between 37 and 97 days. Increase in cellulose and lignin was greater between 37 and 67 days; that of dry matter, between 67 and 97 days. There was no significant change in the percentage of hemicellulose during the period concerned (average 23.2%). The average percentage of silicon compounds in the dry matter was 1.74% in the 37-day samples, fell to 1.56% in the samples collected after 67 days’ growth, and remained at this level in the samples collected after 97 days. Digestibility of the dry matter as determined in vivo (nylon bag technique) was reduced from 78.1% to 50.5% between 37 and 97 days. The reduction was greater between 37 and 67 days (78.1% to 60.5%). There was a significant negative correlation between increase in age of the plants and digestibility. This fact is attributed to the added effects of a gradual thickening of the cell walls and consequent relative decrease in the easily digested cell contents, and of the increase in lignin that accompanied aging. In relation to the characteristics studied, the four varieties of Elephant grass that were compared did not differ significantly and can be recommended indifferently.