Problems which limit the use of rapeseed meal as a protein source in poultry diets

Abstract

The occurrence of a 'fishy' or 'crabby' taint in eggs and liver damage culminating in massive haemorrhage has greatly restricted the commercial utilisation of rapeseed meal as a relatively cheap protein supplement for laying hens in the UK. Recent work on these problems is reviewed. It has elucidated the cause of the taint and identified the rapeseed constituents that are involved. A genetic defect impedes the synthesis of trimethylamine oxidase in susceptible hens and goitrin and tannins inhibit the enzyme. This biochemical lesion severely impairs the metabolism of trimethylamine which is released from sinapine and other dietary sources of choline by enteric bacteria. Consequently, excessive amounts pass into the yolk and produce the taint. Liver haemorrhage is associated with hepatocyte degeneration, abnormalities in the biliary system and the leakage of cellular enzymes into the plasma. The toxic substance(s) responsible has (have) not yet been identified.

Glucosinolates and Glucosinolate Derivatives: Implications for Protection Against Chemical Carcinogenesis

“…The gross toxic effects can be described as reduced feed intake, growth depression, enlargement of target organs (liver, kidneys, thyroid gland) and reproductive disorders such as embryo mortality in mammals and decreased egg production in birds. The intensity of these effects varies with the animal species and, of course, the amount of GSL in their food (Bourdon et al 1981 ;Butler et al 1982;Bell, 1984;Etienne & Dourmad, 1987). In humans, reduced iodine uptake by the thyroid gland was reported after daily ingestion of 500 g cabbage for 2 weeks (Langer et al 1971) or after a single meal of 300 to 500 g swede or turnip (Greer & Astwood, 1948).…”

A method for the decrease of phenolic content in commercial canola meal using an enzyme preparation secreted by the white-rot fungusTrametes versicolor

“…The level of phenolics in CM is 10 to 30 times higher than in soybeans (Dabrowski and Sosulski, 1984;Kozlowska et al, 1990;Zadernowski and Kozlowska, 1983). Although not directly harmful to humans, phenolics are believed to be responsible for changes in the internal organs of livestock and poultry when the meals are included as part of their diet (Butler et al, 1982). The bitter flavor and dark color of the meal and the CM protein concentrates are also related to their presence (Butler et al, 1982;Clandidin, 1961;Goh et al, 1979).…”

“…Although not directly harmful to humans, phenolics are believed to be responsible for changes in the internal organs of livestock and poultry when the meals are included as part of their diet (Butler et al, 1982). The bitter flavor and dark color of the meal and the CM protein concentrates are also related to their presence (Butler et al, 1982;Clandidin, 1961;Goh et al, 1979). Phenolic compounds occur in CM as flavonoids (tannins), lignin, and phenolic acids, and/or their derivatives (Bibi et al, 1991;Kozlowska et al, 1990).…”

Glucosinolates and Sinapine in Camelina Meal

“…However, sinapine has several undesirable properties as a constituent in animal feeds. It is a bitter substance that, if present in the diet of certain brown egg-laying hens at levels exceeding 1 g kg -1 , leads to a fishy odour or taste in the eggs [12]. Especially for the presence of GSLs, the European Food Safety Authority recommends limiting the total GSL content to 1 -1.5 mmol kg −1 of feed for monogastric animals [11], while the US Food and Drug Administration approved inclusion in up to 10% of the weight of the total ration in the diets of beef cattle and poultry [13].…”