This study evaluated the effects of different sources (sulfate vs. hydroxychloride) of Cu, Mn, and Zn during feed restriction and high-starch diet on heifer growth performance. On day 0, Nelore heifers (n = 40) were stratified by body weight (BW = 238 ± 38 kg) and age (21 ± 1 mo), and individually allocated into 1 of 40 drylot pens. The study was divided into periods of pen acclimation (day 0 to 27), nutrient surplus (day 28 to 55), nutrient restriction (day 56 to 83), and step-up adaptation to a high-starch diet (day 84 to 112). Heifers had free choice access to Tifton hay (Cynodon sp.) and salt from day 0 to 27. On day 28, 20 heifers/treatment were randomly assigned to receive free choice access to Tifton hay and protein supplementation at 0.10% of BW (dry matter, DM) added with sulfate (SUL) or hydroxychloride (HYD) sources of Cu, Mn, and Zn from day 28 to 112. From day 56 to 83, heifers were offered 50% of the average hay DM intake obtained from day 50 to 55. From day 84 to 112, each respective protein supplement was mixed with a starch-based total mixed ration (TMR) and concentrate DM amount was gradually increased every 7 days (starting with 35% concentrate and 65% hay on day 84 and ending with 80% concentrate and 20% hay from day 106 to 112). Effects of treatment × day and treatment were not detected (P ≥ 0.37) for heifer BW, fecal pH, average daily gain (ADG), and DM intake, except for ADG from day 28 to 56, which was less (P = 0.05) for SUL vs. HYD heifers. Effects of treatment × day were detected (P = 0.02) for plasma concentrations of insulin-like growth factor 1 (IGF-1) and haptoglobin. Plasma concentrations of IGF-1 were greater (P ≤ 0.05) for HYD vs. SUL heifers on days 56, 70, 77, 84, and 91. Plasma concentration of haptoglobin was greater (P = 0.05) for SUL vs. HYD heifers on day 63. Effects of treatment × day of the study and treatment were not detected (P ≥ 0.35) for plasma concentrations of cortisol, ß-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA). Thus, Nelore heifers offered hydroxychloride sources of Cu, Mn, and Zn exhibited greater plasma concentrations of IGF-1 and a temporary increase in ADG during nutrient surplus compared to those receiving sulfate sources. While hydroxychloride supplementation reduced the acute phase response early in nutrient restriction, it did not improve growth and plasma concentrations of haptoglobin, cortisol, NEFA and BHBA during nutrient restriction and adaptation to a high-starch diet.

中文翻译：

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在饲料限制和适应高淀粉饮食期间，用微量矿物质的羟氯来源代替硫酸盐调节了肉牛的生长性能和炎症和能量代谢的血浆指标


本研究评估了在限制采食和高淀粉饮食期间 Cu、Mn 和 Zn 的不同来源（硫酸盐与羟氯）对小母牛生长性能的影响。在第 0 天，按体重 （BW = 238 ± 38 kg） 和年龄 （21 ± 1 个月） 对 Nelore 小母牛 （n = 40） 进行分层，并分别分配到 40 个干地围栏中的 1 个。该研究分为猪栏适应期（第 0 至 27 天）、营养过剩期（第 28 至 55 天）、营养限制期（第 56 至 83 天）和对高淀粉饮食的逐步适应期（第 84 至 112 天）。小母牛从第 0 天到第 27 天可以自由选择使用 Tifton 干草 （Cynodon sp.） 和盐。第 28 天，将 20 头小母牛/处理随机分配，从第 28 天到第 112 天，自由选择使用蒂夫顿干草和补充 0.10% 的 BW（干物质，DM）并添加硫酸盐 （SUL） 或羟氯离子 （HYD） 来源的铜、锰和锌。从第 56 天到第 83 天，为小母牛提供从第 50 天到第 55 天获得的平均干草干草干物质摄入量的 50%。从第 84 天到第 112 天，将每种蛋白质补充剂与基于淀粉的总混合日粮 （TMR） 混合，精料 DM 量每 7 天逐渐增加（从第 84 天从 35% 浓缩物和 65% 干草开始，到第 106 天到第 112 天从 80% 浓缩物和 20% 干草结束）。未检测到处理×和治疗对小母牛体重、粪便 pH 值、平均日增重 （ADG） 和 DM 摄入量的影响 （P ≥ 0.37），但第 28 天至第 56 天的 ADG 除外，SUL 与 HYD 小母牛的 ADG 较低 （P = 0.05）。检测治疗× 天对胰岛素样生长因子 1 （IGF-1） 和结合珠蛋白浓度的影响 （P = 0.02）。HYD 与 SUL 小母牛在第 56 天、第 70 天、第 77 天、第 84 天和第 91 天的血浆 IGF-1 浓度更高 （P ≤ 0.05）。血浆结合珠蛋白浓度较高 （P = 0.05） 第 63 天的 SUL 与 HYD 小母牛。未检测到研究×天治疗和治疗对皮质醇、β-羟基丁酸酯 （BHBA） 和非酯化脂肪酸 （NEFA） 血浆浓度的影响 （P ≥ 0.35）。因此，与接受硫酸盐来源的小母牛相比，提供 Cu、Mn 和 Zn 的羟氯来源的 Nelore 小母牛表现出更高的 IGF-1 血浆浓度和营养过剩期间 ADG 的暂时增加。虽然补充羟氯物降低了营养限制早期的急性期反应，但在营养限制和适应高淀粉饮食期间，它并没有改善结合珠蛋白、皮质醇、NEFA 和 BHBA 的生长和血浆浓度。