Department of Animal Sciences, University of Illinois, Urbana, IL.
Department of Animal Sciences, Iowa State University, Ames, IA.
J Anim Sci. 2018 Sep 7;96(9):3943-3954. doi: 10.1093/jas/sky253.
To determine the effects of repeated trace mineral injections on heifer development and reproductive performance, commercial Angus heifers (n = 290; 199 ± 34.3 kg; 221 ± 22 d of age) were utilized in a completely randomized design. Heifers were stratified by body weight (BW) and were administered an injectable trace mineral (MM; Multimin 90) or saline (CON) given subcutaneously, post-weaning at 221, 319, 401, and 521 ± 22 d of age. Throughout development, heifers grazed endophyte-infected fescue, red clover pastures and were supplemented with corn distillers grains (2.7 kg per heifer per day) and given access to free choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation and 4- to 7-wk intervals thereafter. Hair coat scores (HCS) and respiration rates (n = 30 heifers per treatment) were collected at 269, 310, and 361 ± 22 d of age. Blood and liver samples were collected at trial initiation and estrous synchronization from 30 heifers per treatment to determine trace mineral status. At 319, 372, and 421 ± 22 d of age, antral follicle count and ovarian size were determined via ultrasonography. Two blood samples from all heifers were collected 10 d apart, concurrent with ultrasound dates, for cyclicity determination. Estrous synchronization was initiated, and reproductive tract scores (RTS) were collected at 421 ± 22 d of age, and heifers were bred via artificial insemination (AI) at 430 ± 22 d of age. Heifer BW, BCS, and HCS did not differ (P ≥ 0.12) throughout development, except at 268 ± 22 d of age when BCS was greater (P = 0.03) for MM than CON heifers. Respiratory rates were greater (P = 0.05) for MM than CON heifers at 269 ± 22 d of age but did not differ (P ≥ 0.66) at 310 and 361 ± 22 d of age. Plasma Mn and Zn concentrations did not differ (P ≥ 0.54). However, MM heifers had greater (P ≤ 0.01) plasma and liver concentrations of Cu and Se compared to CON. Interestingly, MM decreased (P = 0.02) liver Zn concentrations compared to CON, and there was no difference (P = 0.60) in liver Mn. Antral follicle count and ovarian size did not differ (P ≥ 0.51) due to treatment. Throughout development, number of heifers cycling was lesser (P < 0.01) for MM than CON heifers. However, there was no difference (P ≥ 0.19) in RTS, AI pregnancy rates, or overall pregnancy rates. Supplementing an injectable trace mineral increased heifer Cu and Se status; however, no effect was noted on ovarian development or pregnancy rates.
为了确定重复注射痕量矿物质对小母牛发育和生殖性能的影响，利用了 290 头商业安格斯小母牛（199±34.3kg；221±22d 龄）进行完全随机设计。小母牛按体重（BW）分层，并在断奶后 221、319、401 和 521±22d 龄时皮下注射可注射痕量矿物质（MM；Multimin 90）或盐水（CON）。在整个发育过程中，小母牛放牧内生真菌感染的羊茅、红三叶草牧场，并补充玉米酒糟（每头小母牛每天 2.7kg），并允许自由选择无机矿物质。在试验开始时和此后每隔 4-7 周收集小母牛 BW 和体况评分（BCS）。在 269、310 和 361±22d 龄时收集毛被评分（HCS）和呼吸率（每个处理 30 头小母牛）。在试验开始时和从每个处理的 30 头小母牛中同步发情时收集血液和肝脏样本，以确定痕量矿物质状况。在 319、372 和 421±22d 龄时，通过超声检查确定窦卵泡计数和卵巢大小。所有小母牛的两份血液样本在相隔 10 天、与超声日期同时采集，用于确定周期性。在 421±22d 龄时开始同步发情，并采集生殖道评分（RTS），在 430±22d 龄时通过人工授精（AI）对小母牛进行配种。小母牛 BW、BCS 和 HCS 在整个发育过程中没有差异（P≥0.12），除了在 268±22d 龄时，MM 比 CON 小母牛的 BCS 更大（P=0.03）。在 269±22d 龄时，MM 小母牛的呼吸率高于 CON 小母牛（P=0.05），但在 310 和 361±22d 龄时没有差异（P≥0.66）。血浆 Mn 和 Zn 浓度没有差异（P≥0.54）。然而，与 CON 相比，MM 小母牛的血浆和肝脏中 Cu 和 Se 的浓度更高（P≤0.01）。有趣的是，与 CON 相比，MM 降低了（P=0.02）肝脏 Zn 浓度，而肝脏 Mn 没有差异（P=0.60）。由于处理，窦卵泡计数和卵巢大小没有差异（P≥0.51）。在整个发育过程中，MM 小母牛的发情小母牛数量少于 CON 小母牛（P<0.01）。然而，RTS、AI 妊娠率或总妊娠率没有差异（P≥0.19）。补充可注射痕量矿物质可提高小母牛 Cu 和 Se 水平；然而，对卵巢发育或妊娠率没有影响。
