Elisa Manzocchi, Pierre Nozière, Solveig Mendowski, Yves Farizon, Francis Enjalbert, Cécile Martin, Anne Ferlay
The objective was to evaluate the effects of extrusion with or without reducing sugars before extrusion of white lupines on the ruminal biohydrogenation (RBH) of dietary polyunsaturated fatty acids (PUFA), their transfer rates into milk and the milk fatty acid (FA) profile in dairy cows. Sixteen multiparous Holstein cows were assigned to 2 separate replicated 4 × 4 Latin-square design experiments (8 cows in each experiment). Diets contained 20% (DM basis) raw or extruded whole white lupines (Lupinus albus) processed at 115°C, 135°C, or 150°C, without (experiment 1, Exp.1) or with (experiment 2, Exp.2) the addition of reducing sugars. All diets had a forage:concentrate ratio of 69:31 and were isoenergetic, isonitrogenous and iso-starch. In Exp.1, 3 rumen-cannulated cows were included to assess RBH by analyzing ruminal FA profiles 5 h and 17 h post-feeding. Ruminal CH4 production was measured with an automated head-chamber (AHC) system (excluding rumen-cannulated cows, n = 4 in Exp.1, and n = 8 in Exp.2). Extrusion increased the proportion of trans monounsaturated FA (MUFA) and CLA in milk fat, with the greatest effects observed at 150°C, irrespective of sugar addition. Milk from cows fed lupines extruded at 150°C contained higher proportions of n-3 and n-6 PUFA, compared with all other dietary treatments. The RBH of trans-11 C18:1 and cis-9,trans-11 C18:2 was also higher with lupines extruded at 150°C than with raw lupines. Extrusion and temperature of extrusion did not affect CH4 production (g CH4/d). However, CH4 intensity (g CH4/kg ECM) was reduced by 11% on average with lupines extruded at 150°C without addition of reducing sugars compared with raw lupines and lupines extruded at 115°C and 135°C. In conclusion, extrusion of lupines, particularly at 150°C, altered RBH, and increased the proportions of trans MUFA and PUFA in milk fat, but did not reduce CH4 production in dairy cows.