Determination of digestible energy, metabolisable energy and oil digestibility of triple-low rapeseed products for growing and finishing pigs

Abstract

The use of full-fat rapeseed in non-ruminant animal feeding has for long been limited by the presence of anti-nutritive components. However, triple-low varieties have a considerable potential as a source of both protein and dietary energy in diets, although there is the need for precise information on the relative nutritive value of full-fat rapeseed and the resulting extracted oils and meals before they may be effectively and economically incorporated into animal diets.The rapeseed products evaluated comprised ground full-fat rapeseed (FFRS) extracted rapeseed meal (RSM) and rapeseed oil (RSO) all from a triple-low variety, Brassica campestris SVO 333, obtained from Dalgety-Panmure Co. Angus, U.K. The RSO, RSO plus RSM (ORSM) and FFRS were included to give levels of added oil of 40, 80 and 120 g/kg at the expense of the energy-yielding ingredients of the basal diet (Table 1). The RSM was incorporated into the basal at the same rates as in ORSM. All experimental diets were fed to 13 Landrace x (Landrace x Large White) gilts of 46kg average initial live weight in a metabolism trial conducted over four successive time periods. A ten-day acclimatisation in holding pens preceded a 5-day total collection of faeces (using indigo carmine as marker) and urine (facilitated by indwelling bladder catheter) in metabolism crates. The rapeseed products, diets, oven-dried faeces and freeze-dried urine were analysed for gross energy (GE) and (except urine) for oil content. Apparent digestible energy (DE) of test materials were derived by regression analysis. DE of oil was also derived indirectly as a product of oil digestibility and oil GE.