Chemical composition of selected forages and spices and the effect of these spices on in vitro rumen degradability of some forages

Abstract

Spices can be used as novel supplements to enhance the utilization of low quality forages (LQF) and reduce nutrient wastage by ruminant animals. However, it is essential to characterize these spices alongside LQF before testing their potential use as supplements in ruminant diets. This study characterized four spices (cinnamon, cumin, clove and turmeric) alongside three forages (rice straw, wheat straw and hay) for their chemical components before evaluating their effect at four different doses (0, 10, 30 and 90 mg/g forage DM) on the in vitro rumen degradability of dry matter (DM) (IVD) and organic matter (OM) (IVOMD) of these forages at various incubation times. It appeared that some spices could provide complementary nutrients which could improve the utilization of LQF where hay had better chemical composition than the other two forages. Cumin contained more crude protein (CP), ether extract and mineral contents whereas turmeric contained more soluble sugars than the other spices. Cinnamon was least acceptable as a ruminant supplement due to its higher condensed tannin and saponin and lower CP and mineral contents. The IVD and IVOMD were highest for hay and lowest for wheat straw with all spices at all incubation times (p<0.001). Due to relatively better nutrient profiles, cumin and turmeric had greater effect on IVD and IVOMD of the forages. In contrast, cinnamon had negative effects on IVD and IVOMD. IVD and IVOMD were greater at 10 mg/g than at other levels of most spices suggesting that using certain amounts of spices can increase forage degradability. However, the choice of a spice will depend upon the forage type being offered to ruminants. Further studies will examine the effect of these spices on fermentation profile, methane production and nitrogenous loss by ruminants.