Production and chemical composition of lactating dairy cows on pasture submitted to different feeding systems

SUMMARY This study aimed to evaluate the intake, digestibility coefficient of nutrients, production and chemical composition of lactating dairy cows on pasture submitted to different feeding systems: exclusive pasture (PE); pasture associated with sugarcane and urea 1% of the total natural matter (PCU); pasture associated with 4 kg day −1 concentrate supplement (PSC); pasture associated with sorghum silage and 2 kg day −1 concentrate supplement (PSC), and pasture associated with sorghum silage (PSS). The experimental design was a Latin square 5 × 5, consisting of five experimental periods, with fourteen days of adaptation and five days of collection. Consuming dry matter pasture, total dry matter, dry matter in relation to body weight, neutral detergent fiber and totals digestible nutrients, showed no effect (P> 0.10) depending on the feeding systems. It was observed effect systems (P <0.10) on the consumption of crude protein pasture associated with for the concentrated supplement was observed higher consumption 1.50 kg day−1, still, extract ethereal or associated to silage sorghum grass and concentrated supplement 0.19 kg day−1, non-fibrous carbohydrate for pasture associated with the concentrated supplement 2.18 kg dia−1, digestibility of ethereal extract for pasture associated with the concentrate supplement77.79 kg day−1, possibly due to nutritional variations of supplements. Therefore under the conditions of this research regarding the spring-summer period, it is recommended for Dutch-zebu crossbred cows with an average production of 15 kg milk day−1, the exclusive pasture system of Urocloa decumbens, since for the production and chemical composition of the milk Is more feasible.摘要 本研究旨在评估不同饲喂系统下牧场泌乳奶牛的采食量、养分消化率、生产性能及乳化学成分。试验设置的饲喂系统包括：纯放牧组（PE）、甘蔗+占总自然物质1%尿素联用放牧组（PCU）、每日补充4 kg浓缩饲料联用放牧组（PSC）、高粱青贮+每日补充2 kg浓缩饲料联用放牧组（PSC）、高粱青贮联用放牧组（PSS）。本试验采用5×5拉丁方设计，共设5个试验周期，其中适应期14天，数据收集期5天。放牧干物质采食量、总干物质采食量、单位体重干物质采食量、中性洗涤纤维（neutral detergent fiber）及总可消化养分（total digestible nutrients）均未受饲喂系统的显著影响（P>0.10）。饲喂系统对粗蛋白采食量存在显著影响（P<0.10）：添加浓缩饲料组的粗蛋白采食量更高，达1.50 kg·d⁻¹；高粱青贮与浓缩饲料联用时，乙醚浸出物（ethereal extract）采食量为0.19 kg·d⁻¹；添加浓缩饲料组的非纤维性碳水化合物采食量为2.18 kg·d⁻¹；该组的乙醚浸出物消化率为77.79 kg·d⁻¹，上述差异可能与补充饲料的营养组分变异有关。因此，在本研究的春夏季节条件下，针对日均产奶15 kg的荷兰牛-瘤牛（Dutch-zebu）杂交泌乳奶牛，推荐采用俯仰臂形草（Urochloa decumbens，原文笔误为Urocloa decumbens）纯放牧系统，该系统在产奶性能及乳化学成分方面更具可行性。