Ruminal biohydrogenation of fatty acids, protein degradability, and dry matter digestibility of flaxseed treated with different sugar and heat combinations

Abstract

Two experiments were conducted to study the effects of processing techniques on in vitro ruminal undegradable protein (RUP), in vitro ruminal biohydrogenation of fatty acids, and in vitro dry matter digestibility (IVDMD) of rolled flaxseed. In the first experiment, the influence of micronization treatment (130°C for 4 h, 140°C for 2 h, 150°C for 1 h, and 160°C for 0.5 h) was examined. The IVDMD significantly decreased when heating at 150°C for 1 h and 160°C for 0.5 h. Degradation rate of crude protein (CP) decreased and RUP concentration increased in parallel with heating temperature. Micronization had little effect on biohydrogenation of fatty acids. In the second experiment, the influence of sugar addition [none, soaked in a high fructose corn syrup (HFCS) or a lignosulfonate solution] before heating, either in an autoclave or a forced-air oven, at two temperatures (100 or 120°C), and two temperature holding times (30 and 60 min) was examined. Increased temperature and heating time decreased degradation rate of CP and increased the RUP fraction of flaxseeds. There was a decre ase in IVDMD with increased temperature when fructose was added. Moist heating is a better option than dry heating, but it has little advantage over not heating to prevent ruminal biohydrogenation of polyunsaturated fatty acids of flaxseeds. Key words: Biohydrogenation, degradability, in vitro, micronization, lignosulfonate