Effect of total intact glucosinolate intake from rapeseed meals with or without thioglucosidase (EC 3.2.3.1) or copper additions to the diet on the concentrations of 1-cyano-2-hydroxy-3-butene in the ileal digesta and faeces of growing pigs

Studies were made in pigs with cannulae sited near the terminal ileum of concentrations of the nitrile 1-cyano-2-hydroxy-3-butene (CHB) in ileal digesta and faeces consequent from varying daily total intact glucosinolate intakes induced by including in the diet rapeseed meals (200 g kg−1) of different total intact glucosinolate concentrations but of similar individual glucosinolate proportions with progoitrin predominating; a soyabean (SBM) based diet was used as the control. Ileal concentrations were determined from daily intakes (mmol × 103) of 3.5, 23.7 and 53.8, the latter with or without the addition of 200 mg kg−1 copper (Cu) to the diet. Ileal and faecal concentrations were determined, with or without the addition of thioglucosidase (Thio) (EC 3.2.3.1) to the diet, from a daily intake of 46.6 × 103 mmol. No CHB was found either in ileal digesta from the SBM based diet or in faeces from this or from the rapeseed meal based diets. CHB was found in highly variable concentrations between individual animals in ileal digesta when daily total glucosinolate intake was 23.7 × 103 mmol or above with peak concentrations recorded at between 2.5 and 5.5 h after feeding. Within this 3 h period Thio and Cu additions gave inconsistent and very small effects. Whilst these experiments provide evidence of the production of CHB in the foregut of the pig, the significance of this finding relative to either deleterious effects in the animal and/or the production and absorption of CHB in other parts of the gut is not clear and awaits elucidation from further work.