Estimativa da ingestão voluntária a partir das características de degradação do capim-coastcross (Cynodon dactylon L. Pers.), sob pastejo, por vacas em lactação
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Data
2001-07-01
Autores
Berchielli, Telma Teresinha [UNESP]
Soares, João Paulo Guimarães [UNESP]
Aroeira, Luiz Januário Magalhães
Furlan, Cláudia Lopes [UNESP]
Salman, Ana Karina Dias [UNESP]
Silveira, Roselene Nunes da [UNESP]
Malheiros, Euclides Braga [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Zootecnia
Resumo
O consumo de matéria seca (CMS) do capim-coastcross, sob pastejo, de vacas lactantes mestiças (HPB x Gir) e Gir, foi calculado a partir da relação entre a digestibilidade in vitro da MS (DIVMS) da forragem (extrusa colhida com animais esôfago- fistulados) e a produção fecal obtida com auxílio do cromo mordante por meio de um modelo não-linear. A pastagem foi manejada com uma taxa de lotação de 1,6 e 3,2 animais/ha, respectivamente para as épocas seca e chuvosa do ano, num sistema de pastejo rotativo com três dias de ocupação e 27 dias de descanso. Quatro diferentes equações baseadas em variáveis de degradação ruminal foram utilizadas para predizer o consumo de MS: CMS = -1,19 + 0,035 (a+ b) + 28,5c (1), CMS = -0,822 + 0,0748 (a+ b) + 40,7c (2), CMS = -8,286 + 0,266a + 0,102b +17,696c (3) e CMS = [%FDN na MS]* [consumo de FDN ] / [(1-a-b)/K P +b/(c+ k p)]/24] (4). Os dados observados utilizando as equações 1 e 2 (12,2 e 12,7 kg/vaca/dia respectivamente) foram similares entre si e superiores aos resultados obtidos na equação 4 (7,8 kg/vaca/dia). Já o resultado obtido pela equação 3 (5,5 kg/vaca/dia) foi menor do que aqueles determinados pelas outras equações, subestimando o CMS calculado a partir do cromo mordante (6,3 kg/vaca/dia). A predição do consumo de forrageiras tropicais sob pastejo, utilizando equações baseadas nas variáveis de degradação, constitui um importante potencial para estas avaliações. Entretanto, mais estudos devem ser realizados antes de se usarem estas equações na prática.
Dry matter intake (DMI) of coastcross bermudagrass grazing by crossbred Holstein-Zebu and Zebu lactating cows was calculated using in vitro dry matter digestibility from extrusa (four esophageal fistulated cows) and fecal output estimate with mordent chromium by the non linear model. Pasture was managed in a rotational system with three days of occupation and 27 days of resting period, adopting a stocking rate of 1.6 and 3.2 cows/ha respectively during the dry and rainy season. Four different equations based on ruminal degradation were used to predict dry matter intake: DMI = -1.19 + 0.035 (a+ b) + 28.5c (1), DMI = -0.822 + 0.0748 (a+ b) + 40.7c (2), DMI = -8.286 + 0.266a + 0.102b +17.696c (3) and DMI = [%FDN na MS]* [FDN intake] / [(1-a-b)/K P +b/(c+ k p)]/24] (4). The coast-cross DMI predicted by the equations were different from results obtained with the model (6.3 kg of dry matter/cow/day). The data achieved using the equations 1 and 2 (12.2 and 12.7 kg/cow/day respectively) were similar and superior from results obtained by equation 4 (7.8 kg/cow/day). Those values overestimated the results obtained using mordent chromium. The data obtained by equation 3 (5.5 kg/cow/day) was lower than those determined by equations and underestimated the DMI calculated with external marker. The prediction of dry matter intake from cows grazing tropical forages using equations based in ruminal degradation parameters constitutes an important potential for those evaluations, but it should be still studied before being employed in practice.
Dry matter intake (DMI) of coastcross bermudagrass grazing by crossbred Holstein-Zebu and Zebu lactating cows was calculated using in vitro dry matter digestibility from extrusa (four esophageal fistulated cows) and fecal output estimate with mordent chromium by the non linear model. Pasture was managed in a rotational system with three days of occupation and 27 days of resting period, adopting a stocking rate of 1.6 and 3.2 cows/ha respectively during the dry and rainy season. Four different equations based on ruminal degradation were used to predict dry matter intake: DMI = -1.19 + 0.035 (a+ b) + 28.5c (1), DMI = -0.822 + 0.0748 (a+ b) + 40.7c (2), DMI = -8.286 + 0.266a + 0.102b +17.696c (3) and DMI = [%FDN na MS]* [FDN intake] / [(1-a-b)/K P +b/(c+ k p)]/24] (4). The coast-cross DMI predicted by the equations were different from results obtained with the model (6.3 kg of dry matter/cow/day). The data achieved using the equations 1 and 2 (12.2 and 12.7 kg/cow/day respectively) were similar and superior from results obtained by equation 4 (7.8 kg/cow/day). Those values overestimated the results obtained using mordent chromium. The data obtained by equation 3 (5.5 kg/cow/day) was lower than those determined by equations and underestimated the DMI calculated with external marker. The prediction of dry matter intake from cows grazing tropical forages using equations based in ruminal degradation parameters constitutes an important potential for those evaluations, but it should be still studied before being employed in practice.
Descrição
Palavras-chave
cromo mordente, degradabilidade, estimativa de consumo, equações de predição, forrageiras tropicais, Degradability, Intake, mordanted chromium, prediction equations, Tropical forages
Como citar
Revista Brasileira de Zootecnia. Sociedade Brasileira de Zootecnia, v. 30, n. 4, p. 1332-1339, 2001.