Sixty-seven pregnant Angus cows and their subsequent calves were used in a randomized design to evaluate the effect of inorganic Se injection from 80 d of gestation until weaning on cow reproductive parameters, BW and BCS evolution, milk yield and quality, calf growth and calf hematology parameters. The treatments were as follows: 1) Se+: cows were administered Se as sodium selenite at doses of 0.05 mg/Kg of BW at 80, 140, 200, 260 d of gestation and 30, 90, 150 and 240 d of lactation. Calves from Se + cows were Se as sodium selenite subcutaneously injected with a dose of 0.05 mg/Kg of BW at 70, 104, 144 d of age; 2) Control: cows and calves were administered sterile NaCl solution (9 g/l) at the same volume and intervals as Se + treatment. At the start of the experiment, forage Se concentration was 58.6 ppb ± 7.6 ppb, and cow whole blood Se concentration was similar (P > 0.10) between treatments (Se+, 29.3 ± 0.3 ppb; Control, 28.1 ± 0.5 ppb). After Se injection, cow whole blood Se concentration was increased (P < 0.01) in Se + cows in relation to control cows until the end of the experiment. Calf whole blood Se concentration was increased (P < 0.01) at birth and 30 d of age in calves from Se + cows compared to calves from Control cows. However, calf whole blood Se concentration was not different (P > 0.10) between treatments at d 70 after birth. After the first Se injection (70 d of age), calf whole blood Se concentration was increased (P < 0.01) at 104 and 144 d of age in calves from Se + cows compared to calves from Control cows. Cow BW and BCS did not differ (P > 0.10) between treatments throughout the experiment. Ovarian follicle diameter measured by ultrasound 47 d postpartum was greater (P = 0.03) in Se + cows compared to Control cows. Pregnancy rate to fixed time artificial insemination (FTAI), overall pregnancy rate (P > 0.10) and pregnancy loss (P = 0.19) did not differ between groups. Selenium injection did not affect (P > 0.10) milk yield and composition. Calf morphometric parameters, BW at birth and growth rate during lactation were not affected (P > 0.10) by treatments. No significant effect (P > 0.10) was observed between treatments on hematological results of blood samples from calves at weaning. Results of this study shown that inorganic Se injection was an efficient tool to improve Se-status in cow-calf operation under extensive management. Selenium injection increased follicle diameter in postpartum beef cow, however, did not affect the rest of the variables studied.

将67只怀孕的安格斯牛及其后的犊牛用于随机设计，以评估从妊娠80天至断奶前无机硒注射对母牛的生殖参数，体重和BCS演变，产奶量和品质，犊牛生长和犊牛的影响。血液学参数。处理方法如下：1）Se +：以硒的亚硒酸钠形式在母牛的妊娠80、140、200、260 d和泌乳30、90、150和240 d时以0.05 mg / Kg BW的剂量给母牛喂硒。在70、104、144 d年龄分别以0.05 mg / Kg BW皮下注射硒化亚硒酸钠作为Se +母牛的犊牛；2）控制：以与Se +处理相同的体积和间隔，向母牛和犊牛施用无菌NaCl溶液（9 g / l）。在实验开始时，饲草中硒浓度为58.6 ppb±7.6 ppb，两次 处理之间奶牛全血硒浓度相似（P > 0.10）（硒+为29.3±0.3 ppb；对照为28.1±0.5 ppb）。注射 硒后，相对于对照牛，直到实验结束，硒+牛的全血硒浓度均升高（P <0.01）。 与对照组相比，Se +母牛的犊牛在出生时和30 d龄时，其全血硒浓度增加（P <0.01）。但是，小牛全血硒浓度没有差异（P 出生后第70天治疗之间的间隔> 0.10）。在第一次硒注射后（70 d龄）， 与对照组相比，Se +母牛的犊牛在104和144 d时犊牛全血硒浓度增加（P <0.01）。 在整个实验过程中，奶牛的体重和BCS之间没有差异（P > 0.10）。 与对照组相比，Se +母牛在产后47 d超声测得的卵巢卵泡直径更大（P = 0.03）。两组的固定时间人工授精（FTAI）妊娠率，总妊娠率（P  > 0.10）和流产（P  = 0.19）没有差异。硒注射没有影响（P > 0.10）的牛奶产量和成分。小腿形态参数，出生时体重和泌乳期生长率均不受 治疗影响（P > 0.10）。 在两次断奶之间，对犊牛血液样本的血液学结果未见明显影响（P > 0.10）。这项研究的结果表明，在广泛管理下，无机硒注射是改善牛犊操作中硒状态的有效工具。硒注射增加了产后肉牛的卵泡直径，但是并未影响其余的研究变量。