Souza Marjorrie A, Detmann Edenio, Paulino Mário F, Sampaio Cláudia B, Lazzarini Isis, Valadares Filho Sebastião C
Departamento de Zootecnia, Universidade Federal de Viçosa, Viçosa, Minas Gerais, 36571-000, Brazil.
Trop Anim Health Prod. 2010 Aug;42(6):1299-310. doi: 10.1007/s11250-010-9566-6. Epub 2010 Apr 13.
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 x 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 x 4 Latin square design in a 2 x 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%.
本研究旨在评估在以低质量热带牧草为食的牛中，添加含氮化合物和/或淀粉对中性洗涤纤维（NDF）摄入量、消化率及瘤胃动力学的影响。选用了4头体重为231.9±15.5千克且装有瘤胃瘘管的杂交小母牛（荷斯坦×瘤牛）。给动物投喂的牧草为低质量信号草（俯仰臂形草）干草，以干物质（DM）计，平均粗蛋白（CP）水平为51.6克/千克。评估了四种处理方式：对照组，不添加任何物质；添加含氮化合物（粗饲料的CP提高至100克/千克，以DM计）；以200克/千克DM的粗饲料比例添加淀粉；以及如上述那样同时添加含氮化合物和淀粉。尿素、硫酸铵和白蛋白的混合物按4.5:0.5:1.0的比例用作含氮化合物来源。实验按照4×4拉丁方设计以2×2析因排列进行。添加含氮化合物对DM和NDF摄入量有积极影响（P<0.01）。相比之下，添加淀粉会降低牧草摄入量（P<0.10）。添加氮提高了DM和NDF的消化率系数（P<0.05）。同时添加氮和淀粉提高了瘤胃中含氮化合物的微生物同化作用（P<0.05）。我们观察到，添加氮使NDF的估计加权降解率提高了14.8%，而添加淀粉使该率降低了32.5%。
