de Paula Matheus Felipe Freitas Viana, Marques Rodrigo S, Pires Alexandre Vaz, Soares Letícia Carolina Bortolanza, Limede Arnaldo Cintra, Ferreira Evandro Maia, Polizel Daniel Montanher
Department of Nutrition and Animal Production, FMVZ, University of São Paulo, Pirassununga, SP, 13635-000, Brazil.
School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Transl Anim Sci. 2024 Jul 16;8:txae107. doi: 10.1093/tas/txae107. eCollection 2024.
The study aimed to evaluate the effects of forage quality and narasin inclusion on intake, digestibility, and ruminal fermentation of Nellore steers. Twenty-eight rumen-cannulated Nellore steers (initial body weight [] = 350 ± 32.4 kg) were allocated to individual pens in a randomized complete block design, with 7 blocks, defined according to the fasting BW at the beginning of the experiment. The steers were randomly assigned within blocks to 1 of 4 experimental diets in 2 × 2 factorial arrangements, being the first-factor forage quality ( = 81 g of CP/kg of dry matter [], and = 153 g of CP/kg of DM), and the second factor was the inclusion ( = diet plus 13 mg/kg of DM of narasin) or not () of narasin (Zimprova; Elanco Animal Health, São Paulo, Brazil). The experiment consisted of a 28-d period with 22 d for adaptation and the last 6 d for data collection. No haylage quality × narasin interaction (≥ 0.68) was observed on DM and nutrient intake. Haylage quality affected ( ≤ 0.01) DM intake, with greater values observed for steers fed HIGH compared with MEDIUM haylage. There was an increase ( < 0.001) in OM, NDF, hemicellulose, and CP intake for steers consuming HIGH vs. MEDIUM haylage. Including N13 did not affect ( > 0.39) DM and nutrient intake of steers. No haylage quality × narasin interactions were detected (0.60) for total tract nutrient digestibility. However, steers fed with HIGH haylage showed an increase ( > 0.001) in DM and digestibility of all nutrients compared with MEDIUM. Steers fed a MEDIUM haylage had a greater ( < 0.01) proportion of acetate compared with steers fed HIGH during all evaluated hours. Steers fed HIGH haylage had a greater ( < 0.01) proportion of propionate at 0 h compared with steers consuming MEDIUM, whereas at 12 h, steers consuming MEDIUM hay had a greater ( < 0.01) proportion of propionate vs. HIGH haylage. A haylage quality × narasin and haylage quality × time of collection interactions were detected ( ≤ 0.03) for rumen ammonia concentration, which was reduced ( < 0.03) in N13 vs. N0 steers consuming HIGH haylage. Collectively, high-quality haylage allows increased consumption and digestibility, with more energy-efficient ruminal fermentation. In addition, narasin might be an important nutritional tool in forage-based diets to enhance the ruminal fermentation parameters of Nellore steers.
本研究旨在评估饲草质量和添加那拉菌素对内洛尔阉牛采食量、消化率及瘤胃发酵的影响。28头安装了瘤胃瘘管的内洛尔阉牛（初始体重[] = 350 ± 32.4千克）按照随机完全区组设计被分配到各个栏舍，共7个区组，根据实验开始时的空腹体重来定义。阉牛在各区组内被随机分配到4种实验日粮中的1种，采用2×2析因设计，第一个因素是饲草质量（= 每千克干物质中含81克粗蛋白[]，= 每千克干物质中含153克粗蛋白），第二个因素是那拉菌素（Zimprova；巴西圣保罗伊兰科动物保健公司）的添加与否（= 日粮中添加13毫克/千克干物质的那拉菌素）。实验为期28天，其中22天用于适应期，最后6天用于数据收集。在干物质和养分采食量方面，未观察到青贮料质量×那拉菌素的交互作用（≥ 0.68）。青贮料质量影响（≤ 0.01）干物质采食量，与采食中等质量青贮料的阉牛相比，采食高质量青贮料的阉牛干物质采食量更高。与采食中等质量青贮料的阉牛相比，采食高质量青贮料的阉牛的有机物、中性洗涤纤维、半纤维素和粗蛋白采食量有所增加（< 0.001）。添加N13对阉牛的干物质和养分采食量没有影响（> 0.39）。在全消化道养分消化率方面，未检测到青贮料质量×那拉菌素的交互作用（0.60）。然而，与采食中等质量青贮料的阉牛相比，采食高质量青贮料的阉牛的干物质和所有养分的消化率有所提高（> 0.001）。在所有评估时间内，采食中等质量青贮料的阉牛的乙酸比例高于采食高质量青贮料的阉牛（< 0.01）。与采食中等质量青贮料的阉牛相比，采食高质量青贮料的阉牛在0小时时丙酸比例更高（< 0.01），而在12小时时，采食中等质量青贮料的阉牛的丙酸比例高于采食高质量青贮料的阉牛（< 0.01）。在瘤胃氨浓度方面，检测到青贮料质量×那拉菌素和青贮料质量×采集时间的交互作用（≤ 0.03），采食高质量青贮料的N13阉牛与N0阉牛相比，瘤胃氨浓度降低（< 0.03）。总体而言，高质量青贮料可提高采食量和消化率，并使瘤胃发酵更具能量效率。此外，那拉菌素可能是基于饲草日粮中的一种重要营养工具，可改善内洛尔阉牛的瘤胃发酵参数。
