The objective of this study was to compare hydroxy to sulfate sources of Cu and Zn, on growth and reproduction in Angus-based beef heifers. Over a 2 year period, 200 Angus-based, spring-born heifers were stratified by previous winter development treatment and BW to pens and fed either hydroxy (HD, Micronutrients, Indianapolis, IN) or sulfate (SULF; Phibro Animal Health, Teaneck, NJ) to provide 7.2 Mg Cu/kg and 12.3 mg Zn/kg of diet for 68 d Each year there were 4 pens per treatment. The ration consisted of 5.5 kg grass hay, 2.1 kg wet corn gluten feed, and 0.41 kg of a pelleted mineral supplement (DM basis). At the end of the feeding period heifers were synchronized, comingled, and artificially inseminated based on heat detection over a 3 day period. Following this period heifers were exposed to bulls for 60 days while grazing native range. The initial liver Cu and Zn did not differ (P ≥ 0.16) among sources. However, the SULF heifers (208 mg/kg) had greater (P < 0.01) liver Cu than HD heifers (121 mg/kg) at the end of the 68 d feeding period. While liver Zn did not differ among sources (P = 0.40) at the end of the feeding period. Despite differences in liver copper concentrations, gain during and after the mineral source treatment did not differ (P ≥ 0.49) between SULF and HD heifers. Furthermore, no differences (P ≥ 0.92) were observed for AI pregnancy or overall pregnancy. All heifers appeared to have adequate Cu and Zn status at the end of the mineral feeding period which coincided with the beginning of the breeding period; this may explain why trace mineral source had no effects on gains or reproduction.

这项研究的目的是比较羟基和硫酸根来源的铜和锌对安格斯牛小母牛生长和繁殖的影响。在2年的时间里，通过先前的冬季发育处理和BW将200个以安格斯为基础的春季出生的小母牛进行分层，并给围栏喂食，并喂食羟基（HD，微量营养素，印第安纳波利斯，印第安那州）或硫酸盐（SULF; 新泽西州蒂内克市的Phibro Animal Health，提供7.2 Mg铜/ kg和12.3 mg锌/ kg的饮食，持续68天，每年每种治疗使用4支钢笔。配给量为5.5千克草粉，2.1千克湿玉米面筋饲料和0.41千克颗粒状矿物质补充剂（以DM为基础）。在饲喂期结束时，根据三天内的热检测，将小母牛同步化，混合并人工授精。在此之后，小母牛在放牧本地牧场时暴露于公牛60天。初始肝Cu和Zn没有差异（P  ≥0.16）源中。然而，在68 d饲喂期结束时，SULF小母牛（208 mg / kg）比HD小母牛（121 mg / kg）具有更高的（P <0.01）肝脏铜。虽然肝锌在不同来源之间没有差异（P = 0.40）。尽管在和矿物源处理没有差异（后在肝脏中铜的浓度，增益差P  SULF和HD之间的小母牛≥0.49）。此外，没有差异（P  ，观察AI怀孕或整体妊娠≥0.92）。在饲喂期结束时（与繁殖期开始时一致），所有小母牛似乎都具有适当的铜和锌状态。这可以解释为什么微量矿物质源对增产无影响。