Department of Animal Sciences, University of Florida, Gainesville 32611.
Department of Animal Sciences, Federal University of Mato Grosso, Cuiaba, MT, 78060-900, Brazil.
J Dairy Sci. 2020 Aug;103(8):7068-7080. doi: 10.3168/jds.2019-17913. Epub 2020 Jun 3.
Undesirable interactions between trace mineral elements and ruminal contents may occur during digestion when mineral salts are supplemented. Antimicrobial effects of copper sulfate (CuSO) may affect ruminal digestibility of nutrients when fed as a source of copper (Cu), while sodium selenite (NaSeO) may be reduced in the rumen to less available forms of selenium (Se). Our objective was to evaluate if protection of CuSO and NaSeO by lipid-microencapsulation would induce changes on ruminal microbial fermentation. We used 8 fermentors in a dual-flow continuous-culture system in a 4 × 4 duplicated Latin square with a 2 × 2 factorial arrangement of treatments. Factors were CuSO protection (unprotected and protected by lipid-microencapsulation) and NaSeO protection (unprotected and protected by lipid-microencapsulation). Treatments consisted of supplementation with 15 mg/kg of Cu and 0.3 mg/kg of Se from either unprotected or protected (lipid-microencapsulated) sources, as follows: (1) Control (unprotected CuSO + unprotected NaSeO); (2) Cu-P (protected CuSO + unprotected NaSeO); (3) Se-P (unprotected CuSO + protected NaSeO); (4) (Cu+Se)-P (protected CuSO + protected NaSeO). All diets had the same nutrient composition and fermentors were fed 106 g of dry matter/d. Each experimental period was 10 d (7 d of adaptation and 3 d for sample collections). Daily pooled samples of effluents were analyzed for pH, NH-N, nutrient digestibility, and flows (g/d) of total N, NH-N, nonammonia N (NAN), bacterial N, dietary N, and bacterial efficiency. Kinetics of volatile fatty acids was analyzed in samples collected daily at 0, 1, 2, 4, 6, and 8 h after feeding. Main effects of Cu protection, Se protection, and their interaction were tested for all response variables. Kinetics data were analyzed as repeated measures. Protection of Cu decreased acetate molar proportion, increased butyrate proportion, and tended to decrease acetate:propionate ratio in samples of kinetics, but did not modify nutrient digestibility. Protection of Se tended to decrease NH-N concentration, NH-N flow, and CP digestibility; and to increase flows of nonammonia N and dietary N. Our results indicate that protection of CuSO may increase butyrate concentration at expenses of acetate, while protection of NaSeO tended to reduce ruminal degradation of N. Further research is needed to determine the effects of lipid-microencapsulation on intestinal absorption, tissue distribution of Cu and Se, and animal performance.
在补充矿物质盐时，消化过程中痕量矿物质元素和瘤胃内容物之间可能发生不良相互作用。硫酸铜（CuSO）的抗菌作用可能会影响作为铜（Cu）来源的养分在瘤胃中的消化率，而亚硒酸钠（NaSeO）在瘤胃中可能会还原为更不易用的硒（Se）形式。我们的目的是评估脂质微囊化对 CuSO 和 NaSeO 的保护是否会引起瘤胃微生物发酵的变化。我们使用 8 个发酵罐在双流动连续培养系统中进行，采用 4×4 重复拉丁方设计，处理因素为 CuSO 保护（未保护和脂质微囊化保护）和 NaSeO 保护（未保护和脂质微囊化保护）。处理包括补充 15 mg/kg 的 Cu 和 0.3 mg/kg 的 Se，来源为未保护或保护（脂质微囊化），如下所示：（1）对照（未保护的 CuSO+未保护的 NaSeO）；（2）Cu-P（保护的 CuSO+未保护的 NaSeO）；（3）Se-P（未保护的 CuSO+保护的 NaSeO）；（4）（Cu+Se）-P（保护的 CuSO+保护的 NaSeO）。所有日粮具有相同的营养成分，每个发酵罐每天喂 106 g 干物质。每个实验期为 10 天（7 天适应期和 3 天采样期）。每日混合的流出物样品用于分析 pH、NH-N、养分消化率以及总 N、NH-N、非氨氮（NAN）、细菌 N、日粮 N 和细菌效率的流量（g/d）。在喂食后 0、1、2、4、6 和 8 小时采集样本分析挥发性脂肪酸的动力学。主要影响 Cu 保护、Se 保护及其相互作用的所有反应变量均进行了测试。动力学数据作为重复测量进行分析。Cu 的保护降低了乙酸摩尔比例，增加了丁酸比例，并倾向于降低动力学样品中的乙酸：丙酸比，但不改变养分消化率。Se 的保护降低了 NH-N 浓度、NH-N 流量和 CP 消化率；并增加了非氨氮和日粮氮的流量。我们的结果表明，CuSO 的保护可能会增加丁酸的浓度，而以牺牲乙酸为代价，而 NaSeO 的保护则倾向于降低瘤胃中 N 的降解。需要进一步研究以确定脂质微囊化对铜和硒的肠道吸收、组织分布以及动物性能的影响。
