Comparison between the effects of feeding copper sulphate‐treated and untreated rapeseed cake containing high glucosinolates on rumen fermentation, nutrient digestion and nitrogen metabolism in steers

Abstract

Two trials were carried out to study the effects of copper sulphate (CuSO 4 ) on detoxifying glucosinolates (GLS) in rapeseed cake (RSC) and compare the effects of feeding CuSO 4 -treated and untreated RSC on nutrient digestion and nitrogen (N) metabolism in steers. In Trial 1, different concentrations of CuSO 4 solution (1.6 vs. g CuSO 4 •5H2 O 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), CuSO 4 -