This paper surveys the literature concerning biological properties of rapeseed glucosinolates, chiefly the goitrogenic activity of these compounds and their influence on the morphological and histological abnormalities of internal organs in animals. An attempt has been made to establish threshold glucosinolate levels in diet which trigger the onset or increase of internal organs impairment in animals depending on their species and breeding.

Weight maintenance was achieved by feeding either restricted amounts of a high-protein diet (HP) or ad libitum amounts of low-protein diet (LP) to 6 and 20 kp pigs for up to 42 days. In all cases, LP animals consumed approximately three times as much energy as the HP animals but in the 20-kp pigs, almost all (70%) of this excess was deposited in the carcass as fat. In 6-kg pigs fed the LP diet, changes in body energy content accounted for only a small fraction (27%) of the total energy intake; a large difference in energy expenditure was seen between these animals and the HP group, which was attributed to differences in dietary-induced thermogenesis. Six-kilogram LP pigs showed elevated plasma triiodothyronine levels and hepatic mitochondrial alpha-glycerophosphate dehydrogenase activity and an enhanced sensitivity to the in vitro lipolytic effects of norephinephrine (NE) on adipose tissue. These changes are similar to those observed in rats exhibiting dietary-induced thermogenesis and the relevance of these findings to the increased heat production of LP pigs is discussed.

SummaryThis paper has reviewed the current literature relating to the effects of glucosinolates on the palatability of rapeseed meal. The available evidence indicates that diet palatability can be adversely affected by rapeseed meal inclusion and that this response is related to glucosinolate level. However the response is variable and depends also on the species of animal, age and growth state. Younger animals, particularly chicks, piglets and calves appear to be more severely affected and exhibit reduced intake and hence depressed performance with diets containing high levels of glucosinolates from high glucosinolate rapeseed meal. Palatability is substantially improved by the use of low glucosinolate rapeseed meal (LG-RSM) containing 10-30 kg/g and very low glucosinolate rapeseed meal (VLG-RSM) containing 1 -5 pg/g glucosinolates. From the findings of this review, it can be concluded that LG-RSM and VLG-RSM can be included at levels up to 20% and 30% for calves and dairy cows respectively. Since piglets are particularly sensitive it is suggested that rapeseed is excluded from early starter diets but that low glucosinolate meals can be included at levels of 10% and 15% for grower and finisher pigs respectively. Growing poultry may be less sensitivc to palatability problems associated with rapeseed meal but the use of high levels is constrained due to the lower energy and higher fibre contents of RSM compared with soybean meal. ZusammenfassungRapssamenmehl-Glucosinolate und ihre antinutritiven Effekte. 2. Mitt. Aroma und Schmackhaftigkeit Es wird die gegenwartige Literatur uber den EinfluD von Glucosinolaten auf die Schmackhaftigkeit von Rapssamenmehl zusammengefaBt. Die verfugbaren Nachweise zeigen, dal3 die Schmackhaftigkeit einer Diat durch Rapssamenmehl-Zusatz nachteilig beeinfluBt werden kann und rnit dem Glucosinolatgehalt im Zusammenhang steht. Die Reaktion ist jedoch variabel und hangt auch von der Tierart, dem Alter und dem Wachstumszustand ab. Jungere Tiere, insbesondere Kuken, Ferkel und Kalber, werden offensichtlich starker betroffen; sie zeigen eine reduzierte Futteraufnahme und damit eine gestorte Entwicklung bei Diaten, die Rapssamenmehl rnit hohem Glucosinolatgehalt enthalten. Die Schmackhaftigkeit wird deutlich verbessert bei Verwendung von Rapssamenmehl mit niedrigem Glucosinolatgehalt (LG-RSM ; 10 -30 pg Glucosinolat/g) und solche rnit sehr niedrigem Glucosinolatgehalt (VLG-RSM; 1 -5 pg Glucosinolat/g). Aus den Ergcbnissen dieser ubersicht kann geschlossen werden, daD LG-RSM und VLG-RSM bis zu 20% bei KPlbern und bis zu 30% bei Miichkuhen im Futter enthalten sein konnen. Da Ferkel besonders empfindlich sind, wird vorgeschlagen, daD Rapssamenmehl bei Starterdiaten ausgeschlossen wird, dal3 aber LG-RSM bis zu 10% fur groDere und bis zu 15% fur erwachsene Schweine eingesetzt werden kann. Heranwachsendes Geflugel ist wahrschcinlich gegenu ber Geschmacksproblemen in Verbindung rnit Rapssamenmehl weniger empfindlich. Die Verwendung groI3erer Anteile ist aber begrenzt wegen des verringerten Energie-u...

On the basis of literature data biological properties of rapeseed glucosinolates, and especially their influence on the growth and weight of animals were characterized. The aim was to determine a limiting value of these compounds in diets for particular animal species and age groups at which no limitation of growth or development was observed.

Although there is no clear evidence to fully describe the mechanism involved in glucosinolate-related effects on animal reproduction, lowered fertility in animals fed diets with rapeseed meal (RSM) inclusion is related to glucosinolate content in the diet. Negative effects can result both from multidirectional action of glucosinolates, malnutrition of mother due to the thyroid dysfunction, transfer of goitrogenic compounds to foetus and reduced transfer of nutritive compounds (e.g. iodine) through the placenta. The degree of reproduction impairment depends both on glucosinolate content and on the type of animal. Pregnant female rats are sensitive to the presence of glucosinolates, and the first symptoms of fertility impairment and lowering of offspring survival rate may occur at low glucosinolate levels, e.g. with diets containing low glucosinolate rapeseed meal (LG-RSM). In the case of swine, the limiting value above which sows fertility may be impaired is 4 mumol of total glucosinolates per g diet and 8 mmol of daily intake of these compounds. Opinions on the permitted RSM inclusion in diet for hens are very divergent. Some authors recommend limiting of the RSM inclusion to 10%, while others did not find any lowering of egg production in hens fed with two- or three-fold greater RSM inclusion rates. Most long-term experiments with heifers, cows and ewes indicate that ruminants tolerate the level of glucosinolate in LG-RSM although feeding this fodder as the only high-protein concentrate component may lead to impaired fertility.

This review, which will be presented in seven parts is concerned with the use of rapeseed meal as an animal feeding stuff. The presence of glucosinolates in the meal limits its use due to a number of antinutritional and physiological effects. Whilst not in itself exhaustive, this review updates earlier reviews by reference to recent papers on the above topics. In this first paper the history of the crop and the current production situation are presented and the nature of glucosinolates and methods for their analysis are reviewed in order to facilitate a better appreciation of the problems referred in later sections.

From the present review it is clear that glucosinolates and their breakdown products may pass in small amounts into such products as meat, milk or eggs without noticeable deterioration in their taste. When applying low glucosinolate rapeseed meal (LG-RSM) as the sole high protein component of concentrate mixture for cows, the level of rapeseed glucosinolates breakdown products should not exceed 0.1 mumol/l oxazolidinethione, 10 mumol/l unsaturated nitriles and 100 mumol/l thiocyanate. At these levels no evidence has been found to indicate the negative influence of glucosinolates breakdown products on the sensory properties of milk or threat for consumers. No published information appears to be available suggesting that glucosinolates have any deleterious effect on the carcass flavour in cattle. Even at a 20% inclusion of LG-RSM in diets no impairment on visual scores or sensory evaluation was found in pig's or broiler's carcass. Glucosinolated, chiefly progoitrin, which depress trimethylamine oxidation thus clearly affect the taint in eggs. In birds with genetically conditioned susceptibility (brown layers) fishy taint can be observed even at 0.3 microM progoitrin, i.e. approximately 0.5 microM total glucosinolates in 1 g diet. Assuming a threefold higher threshold for white layers (1 microM progoitrin in 1 g diet) fishy taint can be expected at a 10% LG-RSM level in diet, and only very low glucosinolate rapeseed meals can be fed to layers without the risk of fishy taint in eggs.

This paper surveys the effect of some technological processes based on modified traditional way of obtaining oil from rapeseeds and employing polar solvents and enzymes on the content of glucosinolates and nutritional quality of the end products. Special emphasis has been put on the technologies introduced after 1980 tested mostly on a pilot scale.