Intake, digestibility and rumen dynamics of neutral detergent fibre in cattle fed low-quality tropical forage and supplemented with nitrogen and/or starch

• Autor(a) principal: Souza, Marjorrie A.
• Data de Publicação: 2010
• Outros Autores: Detmann, Edenio, Paulino, Mário F., Sampaio, Cláudia B., Lazzarini, Ísis, Valadares Filho, Sebastião C.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://dx.doi.org/10.1007/s11250-010-9566-6; http://www.locus.ufv.br/handle/123456789/19782
• topic: Non-fibrous carbohydrates; Rumen degradation; Rumen fill; Signal grass; Supplementation; Urea

The objective of this work was to evaluate the effects of nitrogenous compounds and/or starch supplementation on the intake, digestibility and rumen dynamics of neutral detergent fibre (NDF) in cattle fed low-quality tropical forage. Four crossbred heifers (Holstein × Zebu) with a body weight 231.9 ± 15.5 kg and fitted with ruminal cannulae were used. The forage fed to the animals consisted of low-quality signal grass (Brachiaria decumbens Stapf.) hay, with an average crude protein (CP) level of 51.6 g/kg, on a dry matter (DM) basis. Four treatments were evaluated: control, without supplementation; supplementation with nitrogenous compounds (CP of the roughage was raised to 100 g/kg), on a DM basis; supplementation with starch at a ratio of 200 g/kg DM of roughage; and supplementation with nitrogenous compounds and starch as described above. A mixture of urea, ammonium sulphate and albumin was used as a source of nitrogenous compounds at a ratio of 4.5:0.5:1.0. The experiment was carried out according to a 4 × 4 Latin square design in a 2 × 2 factorial arrangement. There was a positive effect of the nitrogenous compound supplementation on the DM and NDF intake (P < 0.01). In contrast, starch supplementation decreased forage intake (P < 0.10). Nitrogen supplementation increased the digestibility coefficient of DM and NDF (P < 0.05). Supplementation with nitrogen and starch together increased the microbial assimilation of nitrogenous compounds in the rumen (P < 0.05). We observed that nitrogen supplementation increased the estimated weighted degradation rate of NDF by 14.8%, whilst starch supplementation decreased this rate by 32.5%.