The nutritive value for livestock of UK oilseed rape and rapeseed meal

Summary

A review was made of the literature to investigate the nutritive value of rapeseed products for livestock, with particular emphasis on rapeseed grown in the UK. There were insufficient data to concentrate solely on these varieties, and further research is needed to characterise modern varieties of UK-grown oilseed rape.

Feed intake and performance of livestock fed diets containing rapeseed meal are largely determined by the glucosinolate content of the feed, and modern varieties with low concentrations of glucosinolates are more readily acceptable than the older varieties were. Low glucosinolate rapeseed meal can be used as freely as soyabean meal in the diets of adult ruminant livestock. It can be included in the diets of broilers at rates of up to 200 g/kg, and in finishing pigs at rates of 150 g/kg. However, it is excluded from the diets of most laying hens because of the sinapine present in rapeseed meal that can cause a fishy taint in the eggs of brown-feathered birds. The sinapine content of rapeseed will need to be reduced considerably before producers would be able to include rapeseed products in the diets of their laying flocks.

Full fat rapeseed needs to be finely ground if it is to be utilised efficiently by pigs and poultry. It can be fed to dairy cows as a source of energy and protein, and to alter the fatty acid composition of milk to one that may confer health benefits to people who consume it. However, it is less palatable than rapeseed meal. Among low glucosinolate varieties of rapeseed, there is relatively little difference in the chemical composition between varieties, and little evidence that yellow-coated varieties are any more digestible than brown-coated varieties. However, differences in the amino acid composition of different varieties have not been investigated. There also appears to be little effect of processing on the nutritive value of rapeseed meal, but this has not yet been investigated in the UK.

Future research on rapeseed meal should investigate the effect of UK-grown variety on the amino acid composition and digestibility by different classes of livestock. The development of varieties with low concentrations of sinapine should be pursued, together with the development of effective treatments to reduce the sinapine content of the rapeseed meal. The potential for using rapeseed meal derived from industrial rapeseed (with a high concentration of erucic acid) should be investigated. Research should also address the possible negative effect that rapeseed has on the fertility of heifers, and technology transfer might demonstrate the safe use of relatively high concentrations of rapeseed products in the diets of different classes of farmed livestock.