Two trials were carried out to study the effects of copper sulphate (CuSO₄) on detoxifying glucosinolates (GLS) in rapeseed cake (RSC) and compare the effects of feeding CuSO₄-treated and untreated RSC on nutrient digestion and nitrogen (N) metabolism in steers. In Trial 1, different concentrations of CuSO₄ solution (1.6 vs. 3.2 g CuSO₄·5H₂O L⁻¹), soaking temperatures (25 vs. 60°C) and drying methods (air drying at 60°C vs. freeze drying) were allocated in a 2 × 2 × 2 factorial arrangement in vitro. In Trial 2, six steers and dietary inclusions of untreated RSC (control), CuSO₄-treated RSC and CuSO₄-added RSC were assigned in a replicated 3 × 3 Latin square design. CuSO₄ treatment in vitro decreased the contents of GLS and thiocyanate (TC) in RSC (p < 0.001). The total amount of GLS and TC decreased by 62.7–68.5% for all treatments. The animal trial showed that CuSO₄-treated RSC inclusion decreased ruminal concentration of valerate (p < 0.01), whereas it did not affect ruminal pH, ammonia N and total volatile fatty acids. Compared with the control, feeding CuSO₄-treated or CuSO₄-added RSC had no effect on plasma concentrations of triiodothyronine and thyroxine, N excretion and N retention. CuSO₄-treated RSC tended to increase neutral detergent fibre digestibility (p = 0.072) and urinary excretion of urea (p = 0.056). Urinary excretion of purine derivatives (p = 0.076) and rumen microbial N supply (p = 0.084) tended to decrease when feeding CuSO₄-treated RSC versus control. TC was found to be the only metabolite of GLS in rumen fluid, plasma and urine. It was feasible to detoxify GLS in RSC using low CuSO₄ at room temperature. However, feeding CuSO₄-treated or CuSO₄-added RSC had minor effects on rumen fermentation, nutrient digestion and N metabolism in steers. CuSO₄ treatment on RSC for feeding steers seems to be unnecessary.

中文翻译：

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饲喂硫酸铜处理和未经处理的高硫代硫代葡萄糖苷菜籽饼对肉牛瘤胃发酵、养分消化和氮代谢的影响比较

进行了两项试验，研究硫酸铜 (CuSO ₄ ) 对菜籽饼 (RSC) 中硫代葡萄糖苷 (GLS) 的解毒作用，并比较了饲喂 CuSO ₄处理和未处理的 RSC 对养分消化和氮 (N) 代谢的影响在引导。在试验1中，不同浓度的CuSO ₄溶液（1.6 vs. 3.2 g CuSO ₄ ·5H ₂ O L ^-1）、浸泡温度（25 vs. 60°C）和干燥方法（60°C风干vs.冷冻干燥） ) 在体外以 2 × 2 × 2 因子排列进行分配。在试验 2 中，六头阉牛和未经处理的 RSC（对照）、CuSO ₄处理的RSC 和 CuSO _{4的日粮夹杂物}-添加的 RSC 以重复的 3 × 3 拉丁方设计分配。体外CuSO _{4处理降低了RSC中GLS和硫氰酸盐(TC)的含量(} p  < 0.001)。所有处理的 GLS 和 TC 总量下降了 62.7-68.5%。动物试验表明，CuSO ₄处理的 RSC 包合物降低了瘤胃的戊酸浓度（p  < 0.01），而它不影响瘤胃的 pH 值、氨氮和总挥发性脂肪酸。与对照组相比，饲喂经CuSO ₄处理或添加CuSO ₄的RSC对三碘甲状腺原氨酸和甲状腺素的血浆浓度、N排泄和N保留没有影响。硫酸铜₄经处理的 RSC 倾向于增加中性洗涤纤维的消化率 ( p  = 0.072) 和尿素的尿排泄 ( p  = 0.056)。_{与对照相比，饲喂经 CuSO 4}处理的 RSC时，嘌呤衍生物 ( p  = 0.076) 和瘤胃微生物 N 供应 ( p = 0.084)的尿排泄量 趋于减少。TC被发现是瘤胃液、血浆和尿液中唯一的GLS代谢物。在室温下使用低 CuSO _{4对 RSC 中的 GLS 进行解毒是可行的。}然而，饲喂经CuSO ₄处理或添加CuSO ₄的RSC对肉牛的瘤胃发酵、养分消化和氮代谢影响较小。硫酸铜₄似乎没有必要对 RSC 进行饲喂公牛的治疗。