16 research outputs found
Influence of Particle Size and Density on Particulate Passage Through Alimentary Tract of Holstein Heifers
Dietary Fiber and Fecal Characteristics in Rats: Effects of Level and Particle Size of Bran
Modelagem comparativa da cinética da fase sólida do capim-elefante picado, suplementado ou não com concentrados, e fornecido a vacas Holandês x Zebu em lactação Comparative modeling of chopped elephantgrass particulate kinectics in crossbred lactating cows receiving or not concentrate supplement
Foram comparadas as estimativas da cinética da fase sólida do capim-elefante (Pennisetum purpureum, Schum.) picado, mordentado com cromo (Cr), obtidas do ajuste de dois modelos não-lineares (bicompartimental tempo-independente e multicompartimental tempo-dependente) a resultados de excreção fecal de vacas Holandês x Zebu em lactação. Utilizaram-se dados de dois experimentos realizados em anos diferentes com capim-elefante cortado aos 60 e 45 dias, e suplementado, 3,3kg/vaca/dia, base matéria natural, ou não com concentrados. Foram utilizadas quatro e três vacas, respectivamente, no primeiro e no segundo ano de experimentação, havendo sempre duas fases de coleta de dados, necessárias para permitir que cada vaca pudesse ser avaliada em cada tratamento. As taxas de passagem ruminal estimadas variaram de 3,0 a 3,2%/h no modelo bicompartimental tempo-independente, e de 2,6 a 3,0%/h no modelo multicompartimental tempo-dependente, enquanto as respectivas taxas de passagem pós-ruminal variaram de 4,9 a 7,4%/h e de 7,4 a 10,9%/h. Os tempos médios de retenção do capim-elefante no trato gastrintestinal das vacas variaram de 66,0 a 76,2h no modelo bicompartimental tempo-independente, e de 48,1 a 57,8h no modelo multicompartimental tempo-dependente. O processo de dependência de tempo imposto pelo modelo multicompartimental permitiu melhor ajuste aos dados de excreção fecal do Cr, em relação ao modelo bicompartimental.<br>Particulate kinetics estimates of chopped elephantgrass (Pennisetum purpureum, Schum.) mordanted with Chromium (Cr) were obtained and compared by the adjustment of two nonlinear models - age-independent double-compartmental model and age-dependent multicompartmental model - to a Cr faecal excretion dates of lactating crossbred Holstein x Zebu cows. Results from two trials carried out in different years with elephantgrass cut at 60 and 45 days of growth and supplemented, 3,3 kg/cow/day, wet basis, or not with concentrates were used. Four cows in the first and three cows in the second year were used and in each year there were two phases of collection of data, necessary to allow that each cow could be evaluated in each treatment. The ruminal particulate passage rates of chopped elephantgrass ranged from 3.0 to 3.2%/h in age-independent double-compartmental model, and from 2.6 to 3.0%/h in age-dependent-multicompartmental model, while that the respective post-ruminal passage rates ranged from 4.9 to 7.4%/h and from 7.4 to 10.9%/h. The total mean retention time of the elephantgrass in the gastrointestinal tract ranged from 66.0 to 76.2 h in age-independent double-compartmental model, and from 48.1 to 57.8 h in age-dependent-multicompartmental model. The implicit assumption of age-dependence for the multicompartimental model allowed better fit to the data of faecal excretion Cr than that one of the double-compartmental model