Department of Animal Science, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil.
Department of Animal Science, College of Agricultural Sciences, Colorado State University, Fort Collins 80523.
J Dairy Sci. 2019 Apr;102(4):2973-2984. doi: 10.3168/jds.2018-15166. Epub 2019 Feb 7.
International committees that have published nutrient requirements for dairy cattle have used data from mineral studies conducted in the 1920s to 1970s, and no study has reported data from animals less than 100 kg; therefore, there is a need to update mineral requirements for preweaned dairy calves. Thus, a meta-analysis was performed to estimate the mineral requirements of Ca, P, K, Mg, and Na for Holstein and Holstein × Gyr crossbred preweaned dairy calves using data from 5 studies developed at the Universidade Federal de Viçosa (Viçosa, MG, Brazil). A total of 210 calves were separated into 2 breeds: purebred Holstein calves (animals with a Holstein pedigree higher than 87.5%) and Holstein × Gyr crossbred calves (animals with a Holstein pedigree lower than 87.5%). The comparative slaughter technique was used to estimate animal body composition and empty body weight (EBW). Mineral requirements for maintenance were estimated by the regression between retained mineral and mineral intake, whereas mineral requirements for gain were obtained from the first derivative of the mineral content in the animal's body. In addition, breed effect was tested on the intercept and slope of the models. The effect of breed was not observed for all analyzed variables. Thus, net requirements for maintenance were 12.73, 11.81, 20.28, 3.50, and 6.37 mg/kg of EBW per day for Ca, P, K, Mg, and Na, respectively. Retention coefficients were 73.18, 65.20, 13.16, 29.55, and 24.28% for Ca, P, K, Mg, and Na, respectively. The following equations were determined to estimate net requirements for gain (NRG, g/d): NRG for Ca = 14.402 × EBW × empty body gain (EBG); NRG for P = 5.849 × EBW × EBG; NRG for K = 1.140 × EBW × EBG; NRG for Mg = 0.603 × EBW × EBG; and NRG for Na = 1.508 × EBW × EBG. Due to the high variation between the data found in this study and in the available literature, we suggest that further studies should be conducted to evaluate the estimates of this study.
国际奶牛营养委员会使用了 20 世纪 20 年代至 70 年代进行的矿物质研究数据来制定奶牛的营养需求，但没有研究报告过体重低于 100 公斤的动物的数据；因此，有必要更新奶牛小牛的矿物质需求。因此，进行了一项荟萃分析，以使用来自巴西维索萨联邦大学（米纳斯吉拉斯州维索萨）的 5 项研究的数据来估计荷斯坦和荷斯坦×吉尔杂交小牛的钙、磷、钾、镁和钠的矿物质需求。共有 210 头小牛分为 2 个品种：纯种荷斯坦小牛（具有高于 87.5%的荷斯坦血统的动物）和荷斯坦×吉尔杂交小牛（具有低于 87.5%的荷斯坦血统的动物）。使用比较屠宰技术估计动物体成分和空腹体重（EBW）。通过保留矿物质与矿物质摄入之间的回归来估计维持所需的矿物质，而通过动物体内矿物质含量的一阶导数获得生长所需的矿物质。此外，还对模型的截距和斜率进行了品种效应检验。所有分析变量均未观察到品种效应。因此，维持的净需求量分别为钙、磷、钾、镁和钠每日 12.73、11.81、20.28、3.50 和 6.37 毫克/公斤 EBW。保留系数分别为钙、磷、钾、镁和钠的 73.18、65.20、13.16、29.55 和 24.28%。确定以下方程来估计净生长需求（NRG，g/d）：NRG 为钙= 14.402×EBW×空腹体增重（EBG）；NRG 为磷= 5.849×EBW×EBG；NRG 为钾= 1.140×EBW×EBG；NRG 为镁= 0.603×EBW×EBG；NRG 为钠= 1.508×EBW×EBG。由于本研究中的数据与现有文献中的数据之间存在较大差异，因此我们建议应进一步开展研究来评估本研究的估计值。
