Effects of high fat rapeseed press cake on growth, carcass, meat quality and body fat composition of leaner and fatter pig crossbreeds

A 3 X 2 factorial experiment with a total of 60 male castrated pigs, live-weight range 24 to 104 kg, was carried out to test three dietary levels of high fat rapeseed press cake in two crossbreeds differing in carcass lean. The six groups with 10 pigs each representing either crossbreeds of Landrace (LR) X (LR X Large White (LW)) (groups 1, 3 and 5) or Pietrain (Pi) X (LR X LW) (groups 2, 4 and 6) were each offered, ad libitum, diets without rapeseed press cake (groups 1 and 2), or with rapeseed press cake: 75 g/kg diet (groups 3 and 4) or 150 g/kg diet (groups 5 and 6). The press cake produced in a small oil press contained 341 g crude protein per kg dry matter (DM), 181 g ether extract per kg DM and 23.3 mmol glucosinolates per kg DM. Rapeseed press cake, particularly at 150 g (3.2 mmol glucosinolates) per kg diet, lowered food intake and weight gain, though only significantly in the Pi-sired hybrids. There were no effects of the diets on leanness, whereas the 550 g/kg of carcass lean of Pi-sired pigs was significantly higher than the 510 g/kg of LR-sired hybrids. Meat of the Pi-sired crossbreeds showed a lower pH (tendency), higher conductivity, lower impedance and higher drip loss. At 150 g/kg diet rapeseed press cake LR-sired crossbreeds showed the darkest meat and the Pi X LR, LW hybrids the lowest sensory evaluation score. In LR-sired hybrids the rapeseed press cake diets increased the backfat polyunsaturated fatty acids (PUFA) to a lower degree (1.3% per 10 g rape oil increase in 1 kg diet) than in Pi-sired hybrids (2.6% per 10 g rapeseed increase in 1 kg diet). Using simple correlation coefficients, the sensory evaluation results were negatively correlated with carcass lean and tended to be so with meat fat PUFA content. Pigs should receive less than 2 mmol glucosinolates per kg diet corresponding to 50 to 100 g double zero rapeseed products per kg diet. Rape oil should be recommended according to the animals lean and fat status, respectively. Fatter pigs may receive a maximum of 40 g, leaner pigs a maximum of 20 g rape oil per kg diet.