The concentration of Co in the herbage of a large proportion of grassland farms in Ireland is lower than that required by sheep. The effects of supplementing ewes with Co, and method of supplementation, on ewe and offspring performance, were evaluated over 2 years. The ewes (359 in year 1, 241 in year 2), representing 3 genotypes, were allocated to one of 3 treatments. The treatments were: Control - no supplementation; Drench – Co supplementation via oral drench (31.5 mg Co as CoSO₄•7H₂O) administered every 14 days; Bolus – Co supplementation via rumen bolus (effective life of ∼6 months) that only contained Co as CoSO₄•7H₂O with an expected Co release rate of 0.6 mg/day in year 1 and 1 mg/day in year 2. Drench treatment was administered from 7 weeks pre joining, until 6 weeks prior to expected lambing date (early – to mid - March). One bolus was administered to ewes on the bolus treatment at the start of the study (day 0) each year. The ewes were managed as one flock in a rotational-grazing system until housing in early December each year; they were shorn at housing and offered grass silage ad libitum plus a concentrate supplement during late pregnancy. Ewes and lambs were put to pasture within 3 days of lambing. Supplementation with Co, via drench or bolus, increased the concentration of Co (P < 0.001) and vitamin B₁₂ in ewe plasma at ∼day 50 and ∼day 100 of pregnancy and these effects were generally greater for Drench than Bolus treatments. Supplementary Co had no effect (P > 0.05) on ewe BW or body condition score at joining (day 49), mid-pregnancy, lambing, 5 weeks post lambing or weaning. Likewise, supplementation had no effect (P > 0.05) on litter size, lamb mortality or number of lambs reared per ewe joined, or on lamb BW at birth or weaning. The only significant animal-performance difference detected between the Bolus and Drench treatments concerned the incidence of lambs classified as ‘born dead or died within 24 h of birth’ (3.1% for Drench, 6.5% for Bolus; P < 0.05). It is concluded that, whilst supplementing ewes (high proportion whom (30 to 60%) had marginal plasma B₁₂ status) with Co from 7 weeks pre-joining until late pregnancy increased plasma Co and vitamin B₁₂ concentrations and reduced the proportion classified as having marginal or low Co status. There was no effect on ewe or progeny performance.

爱尔兰大部分草原农场的牧草中 Co 的浓度低于绵羊所需的浓度。对母羊补充 Co 和补充方法对母羊和后代性能的影响进行了 2 年的评估。代表 3 种基因型的母羊（第 1 年 359 头，第 2 年 241 头）被分配到 3 个处理中的一个。处理是：对照-不补充；灌水 –每 14 天通过口服灌水补充钴（31.5 毫克 Co，作为 CoSO ₄ •7H ₂ O）；丸剂 – 通过瘤胃丸剂补充 Co（有效寿命约为 6 个月），仅含有 Co 作为 CoSO ₄ •7H ₂O 的预期 Co 释放率在第 1 年为 0.6 毫克/天，在第 2 年为 1 毫克/天。从加入前 7 周到预期产羔日期前 6 周（3 月初至中旬）进行淋水处理. 每年在研究开始时（第 0 天）对母羊进行一次推注。母羊在轮牧系统中作为一个羊群管理，直到每年 12 月初入舍；他们在住房时被剪毛，并在怀孕后期随意提供青贮饲料和浓缩补充剂。母羊和羔羊在产羔后 3 天内放牧。通过灌药或丸剂补充 Co，增加了 Co (P < 0.001) 和维生素 B ₁₂的浓度在妊娠 50 天和 100 天的母羊血浆中，这些影响通常比大丸剂治疗更大。在加入（第 49 天）、怀孕中期、产羔、产羔后 5 周或断奶时，补充 Co 对母羊的体重或身体状况评分没有影响（P > 0.05）。同样，补充对产仔数、羔羊死亡率或每头母羊饲养的羔羊数量或出生或断奶时的羔羊体重没有影响（P > 0.05）。在 Bolus 和 Drench 处理之间检测到的唯一显着动物性能差异涉及归类为“出生死亡或出生后 24 小时内死亡”的羔羊的发生率（Drench 为 3.1%，Bolus 为 6.5%；P < 0.05）。得出的结论是，在补充母羊（高比例（30% 至 60%）的血浆 B ₁₂状态）与 Co 从加入前 7 周到妊娠晚期增加了血浆 Co 和维生素 B ₁₂浓度，并降低了被归类为边缘或低 Co 状态的比例。对母羊或后代的性能没有影响。