Cinética da degradação ruminal dos carboidratos de quatro gramíneas tropicais em diferentes idades de corte e doses de adubação nitrogenada: técnica de produção de gases

Abstract

RESUMO -Objetivou-se neste experimento avaliar a cinética de degradação ruminal dos capins setária (Setaria anceps Stapf), hemarthria (Hemarthria altissima [Poir] Stapf. & Hubbard), angola (Brachiaria purpurascens [Raddi] Henr.) e acroceres (Acroceras macrum Stapf.) adubados com 0, 100, 200, 300 ou 400 kg de N/ha e colhidos aos 28, 42, 56 ou 70 dias de idade. Os resultados foram avaliados por intermédio de análise de fatores. Após redução e avaliação da variação conjunta total das variáveis, optou-se pela adoção de três fatores, que englobaram 86,4% da variação total: o primeiro fator (Fator 1) associou-se ao volume de gás oriundo das frações de lenta e de rápida degradação e à taxa de degradação da fração rapidamente degradável (Vf 1, Vf 2 e k 2 ); o segundo fator (Fator 2) associou-se à taxa de degradação results were submitted to a factor analysis. After reduction and evaluation of the combined variation from the total variables, three factors comprising 86.44% of the total variation were considered, where the first factor (Factor 1) was strongly associated with the gas volume of substrates of slow and rapid digestion, as well as the fractional rate of substrate of rapid degradation (Vf 1 , Vf 2 and k 2 ). The second factor (Factor 2) was associated to the fractional degradation rate of the slow degradable substrate and lag phase (k 1 and L) and the third factor (Factor 3) was related to the in vitro dry matter digestibility (IVDMD). Cutting age had an effect on the grass kinetics, where the growth age resulted on reduced IVDMD.No significant responses of the supply of nitrogen fertilizer in relation to the parameters analyzed were found. Due to its high digestibility, the Limpo grass demonstrated to have an outstanding performance when compared to the other grasses.Key Words: California grass, degradation rate, gas production, Limpo grass, Nilo grass, Setaria grass IntroduçãoConsiderando que o valor nutritivo das plantas forrageiras pode ser influenciado por práticas de manejo, técnicas têm sido desenvolvidas para permitir que estas plantas expressem todo o seu potencial agronômico de produção e resultem em maior desempenho animal. Freqüên-cias de corte (ou pastejo) e níveis de adubação nitrogenada têm apresentado boas respostas, principalmente no valor nutritivo (Pinto et al., 1994

Nutritional divergence in genotypes of forage peanut

“…These high values for VF1 are due to the higher NFC content presented by these genotypes (Table 2), conferring greater availability of fermentable substrate and providing greater gas production for this fraction. Degradation rates for the rapidly degradable fraction (C1) were low, averaging 0.068/h, since reports of values from 0.1 to 0.2/h, are frequent (Cabral et al, 2003;Senger et al, 2007;Detmann et al, 2009). The highest gas productions from the fermentation of the slowly degradable fraction (VF2) were found for accessions 31828 and 31534.…”

In vitro rumen fermentation kinetics of diets containing oldman saltbush hay and forage cactus, using a cattle inoculum

“…According to Detman et al (2009), although the lag represented by the model of Schofield et al (1994) results from mixed origins (i.e., common to the two digestion compartments), the fibrous fraction can be directly associated with most of the lag-related events, thereby accounting for the greater lag observed with feeds containing higher proportions of lignin. The diet composed of 48.3% oldman saltbush hay exhibited a greater Lag period (3 hours and 41 minutes).…”

Productivity and nutritional quality of Flechinha grass ( Echinolaena inflexa ), native grass of Brazilian Cerrado

“…Both forages had higher TC and NFC contents during the rainy season. Tropical forages, during the dry season, have lower carbohydrate contents than those observed during the rainy season because those carbohydrates migrate to the basis of the stalk (DETMANN et al, 2009). E. inflexa had lower NFC contents than B. brizantha during both seasons.…”