The thiocyanate ion (SCN⁻) content of eggs from hens (Gallus domesticus) fed on a diet containing rapeseed meal

Abstract

The antimicrobial effect of the lactoperoxidase-thiocyanate-hydrogen peroxide system has been recognised in milk and other biological fluids. In this study the main object was to determine whether the inclusion of 10% rapeseed meal (RSM) in layers' diet could enhance the levels of the thiocyanate ion (SCN-) in eggs to a level required by the LP system to promote bactericidal activity in egg products. Twelve 'Abor Acre' pullets were divided into two lots, separately housed and maintained under similar conditions. One lot was fed on a basal diet and the other on an experimental diet containing 10% RSM. Both diets were of known composition, isoenergetic and isonitrogenous. Throughout the feeding trials (15 weeks) a record was kept of egg productivity, individual egg weight and layers weight. Subsequently, the weekly lots of eggs were analysed for thiocyanate ions (SCN-) by gas chromatography. The colour of each yolk was measured using the 'Roche Colour Fan' and organoleptic assessments were made for the detection of trimethylamine taint since the feeding of RSM has been reported to influence these factors. No significant difference was recorded in the average weight of eggs obtained from both groups. However, egg production was 15 % higher with RSM fed hens which lost a little weight. No taint was detected in either set of eggs and no significant variation in yolk colour was noted. After 4 weeks the levels of SCN-reached 1.6 mg kg-l in the experimental eggs and then remained almost constant. The control set had an average of 0.5 mg kg-1 SCN-. Hence an enhancement of the SCN-levels can be achieved in shell eggs by incorporating 10% RSM in the layers' diet. This enhancement is of the order claimed necessary for the operation of this system.

The Deposition and Elimination of Glucosinolate Metabolites Derived from Rapeseed Meal in Eggs of Laying Hens

“…The limit of determination is 1.0 mg/kg in the present study, thus the difference of analysis method might cause the different results. The SCN – content of eggs did not increase progressively and remained almost constant after a 4-week administration of RSM, which was in line with Shuaib et al, who reported that the levels of SCN – reached 1.6 mg/kg in the experimental eggs and then remained almost constant after 4 weeks of administration of 10% RSM diet . Moreover, Mabon et al showed that the SCN – concentration in the plasma increased during the first 3 weeks and then stayed relatively constant until the end of the experiment…”

“…The SCN − content of eggs did not increase progressively and remained almost constant after a 4-week administration of RSM, which was in line with Shuaib et al, who reported that the levels of SCN − reached 1.6 mg/kg in the experimental eggs and then remained almost constant after 4 weeks of administration of 10% RSM diet. 33 Moreover, Mabon et al showed that the SCN − concentration in the plasma increased during the first 3 weeks and then stayed relatively constant until the end of the experiment. 32 Although 5-VOT appeared in FDA Poisonous Plant Database, 5 there was no limit of 5-VOT in food.…”

“…The SCN – could not be detected in eggs of hens fed with control diet during the accumulation phase. However, Shuaib et al showed that the control group had an average of 0.5 mg/kg SCN – detected by gas chromatography. The limit of determination is 1.0 mg/kg in the present study, thus the difference of analysis method might cause the different results.…”