Effect of extrusion-cooking temperature on the nutritive value of lupin seeds in fattening lambs

Twelve Polish-Merino lambs, divided into two groups of 6, were fattened fro m 18 to 39 kg body weight on diets containing 14% crude protein and 11% cru de fibre in dry matter; 25% of crude protein was From untreated lupin seeds or a mixture of lupin extruded at 160 degreesC with barley(l:l). Daily bod y weight gains of lambs fed extruded lupin seeds were higher (P <0.5) than those of lambs fed the untreated lupine-barley mixture (234 vs 186 g). Feed efficiency was 5.0 kg dry matter and 729 g crude protein in lambs fed the untreated lupine-barley mixture and 4.2 kg dry matter and 597 g crude prote in in animals receiving the extruded mixture. Effective protein degradability of untreated lupin was 0.85, untreated barl ey 0.75 or untreated lupin-barley mixture 0.80, whereas that of extruded at 130, 140, 150 or 160 degreesC lupin-barley mixtures gradually decreased fr om 0.70 to 0.67. The respective effective protein degradability values for barley extruded at 135 or 155 degreesC were 0.72 and 0.60. The coefficient of intestinal protein digestion of untreated lupine was 0.59, of barley, 0. 83, and of the lupin-barley mixture, 0.71, whereas for extruded lupin-barle y mixtures, it only slightly increased with temperature from 0.92 to 0.94, while for extruded barley from 0.91 to 0.92. Substitution of unprocessed lupin seeds with extruded seeds decreased prote in degradation in the rumen, increased protein intestinal digestibility and effectiveness of fattening lambs. Increasing the extrusion temperature to over 130 degreesC did not significantly improve degradability in the rumen or intestinal digestibility of protein.