The effects of dietary consumption of plants secondary compounds on small ruminants' products quality

Worldwide policies are encouraging the use of natural rangelands and low input feeding resources for livestock farming. Most of the low input feed contain secondary compounds (PSCs) - such as phenolic compounds (PhCs), saponins, and essential oils (EO) - which play a primary role on animal digestion and performances and also on product quality. Meat and milk fatty acid composition can be manipulated by dietary tannins as these PSCs modify ruminal biohydrogenation of dietary polyunsaturated fatty acids through changes in ruminal ecology. Dietary tannins improve products' flavour by reducing the ruminal biosynthesis of skatole and its accumulation in meat and milk. The addition of garlic or juniper EO in lamb diets reduces the off-flavours perception while thyme or rosemary EO lowered the rancid-odour perception of meat under display. It is proved that dietary PhCs ameliorate meat oxidative stability and prevent meat from discoloration thus extending product shelf life. The dose-response effect of these PSCs as well as their mechanisms of action are not fully unravelled. Nevertheless, the use of plants rich in secondary compounds or the supplementation of purified PSCs in small ruminants diet seem to be a promising strategy for improving products quality. (C) 2011 Elsevier B.V. All rights reserved.