Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
J Anim Sci. 2022 Sep 1;100(9). doi: 10.1093/jas/skac246.
Fifty-four Angus-cross steers (297 kg ± 12) were stratified by body weight (BW) to pens (six steers per pen) to determine the effects of supplemental Zn on posttransit growth performance and blood and muscle metabolites. Dietary treatments started 25 d before trucking: control (CON; analyzed 54 mg Zn/kg DM), industry (IND; CON + 70 mg supplemental Zn/kg DM), and supranutritional Zn (SUPZN; CON + 120 mg supplemental Zn/kg DM). Supplemental Zn was bis-glycinate bound Zn (Plexomin Zn; Phytobiotics North America, Cary, NC). On day 0, steers were loaded onto a commercial trailer and transported in 18 h (1,822 km). Individual BW was recorded on days -26, -25, -1, and 0 (pre-transit), 1 (posttransit), 6, 27, and 28. Blood was collected on days -1, 1, 6, and 27. Longissimus thoracis biopsies were collected on days -1, 1, and 28. Daily individual feed disappearance was recorded via GrowSafe bunks. Data were analyzed using Proc Mixed of SAS with fixed effect of diet and steer as the experimental unit (growth performance, blood: n = 18 steers per treatment; muscle: n = 12 steers per treatment). Individual initial BW was used as a covariate in BW analysis. Contrast statements to test linear, quadratic, and Zn effects were used to analyze performance and blood parameters. Repeated measures analysis was used for posttransit DMI recovery and weekly posttransit DMI and Zn intake with the repeated effect of time. MetaboAnalyst 5.0 was utilized for statistical analysis of day 1 (off truck) muscle metabolites. Plasma Zn linearly increased due to Zn on days 1, 6, and 27 (P = 0.01), and off-truck (day 1) serum lactate increased over day -1 by 20%, 0%, and 20% in CON, IND, and SUPZN, respectively (Quadratic: P = 0.01). Muscle lactate tended to increase posttransit in CON and IND (P ≤ 0.07) but not SUPZN. Muscle metabolites relating to amino acid and nitrogen metabolism were increased in all treatments posttransit (P ≤ 0.02), and alanine-glucose cycle metabolites tended to increase in CON and IND (P ≤ 0.07). Steers supplemented with Zn recovered pretransit DMI quicker than CON (by d 2: P = 0.01), while IND had greater overall posttransit DMI than CON with SUPZN intermediate (P = 0.04), and Zn-fed steers had greater ADG posttransit (P = 0.04). Zinc supplementation mitigated muscle or serum lactate increases due to transit and increased posttransit ADG.
54 头安格斯杂交公牛（297 公斤±12）按体重（BW）分层到围栏（每围栏 6 头公牛），以确定补充锌对转运后生长性能以及血液和肌肉代谢物的影响。日粮处理在运输前 25 天开始：对照组（CON；分析 54 毫克锌/公斤 DM）、工业组（IND；CON+70 毫克补充锌/公斤 DM）和超营养锌组（SUPZN；CON+120 毫克补充锌/公斤 DM）。补充锌为双甘氨酸结合锌（Plexomin Zn；Phytobiotics North America，Cary，NC）。在第 0 天，公牛被装载到商业拖车上，并在 18 小时内运输（1822 公里）。个体 BW 于-26、-25、-1 和 0 天（转运前）、1 天（转运后）、6 天、27 天和 28 天记录。于-1、1、6 和 27 天采集血液。于-1、1 和 28 天采集背最长肌活检。通过 GrowSafe 卧床每天记录个体的饲料消失量。数据使用 SAS 的 Proc Mixed 进行分析，固定效应为日粮和公牛作为实验单位（生长性能、血液：每个处理 18 头公牛；肌肉：每个处理 12 头公牛）。BW 分析中使用个体初始 BW 作为协变量。用于分析性能和血液参数的线性、二次和 Zn 效应的对比语句。转运后 DMI 恢复以及每周转运后 DMI 和 Zn 摄入量的重复测量分析使用时间的重复效应。使用 MetaboAnalyst 5.0 对第 1 天（下车）肌肉代谢物进行统计分析。由于第 1、6 和 27 天的 Zn，血浆 Zn 呈线性增加（P=0.01），并且在下车（第 1 天）时，血清乳酸在 CON、IND 和 SUPZN 中分别增加了 20%、0%和 20%（二次：P=0.01）。CON 和 IND 中的肌肉乳酸在转运后趋于增加（P≤0.07），但 SUPZN 中没有。所有处理组的肌肉氨基酸和氮代谢相关代谢物在转运后均增加（P≤0.02），并且 CON 和 IND 中的丙氨酸-葡萄糖循环代谢物趋于增加（P≤0.07）。与 CON 相比，补充 Zn 的公牛在转运后更快地恢复了预转运 DMI（第 2 天：P=0.01），而 IND 比 CON 具有更高的总体转运后 DMI，而 SUPZN 居中（P=0.04），并且 Zn 饲养的公牛在转运后具有更高的 ADG（P=0.04）。补充 Zn 缓解了由于转运引起的肌肉或血清乳酸增加，并增加了转运后的 ADG。
