Rumen degradation characteristics of different neutral detergent fiber/starch ratio diets in dairy cattle

This experiment was conducted to evaluate the rumen degradation characteristics of four different neutral detergent fiber/starch ratio diets. Silage maize, oat grass and corn grain were used to adjust the NDF/Starch ratio. Four total mixed rations were fed with different NDF/Starch in ratios of 0.86(Ⅰ),1.13(Ⅱ),1.56(Ⅲ) and 2.38(Ⅳ), respectively. Three healthy Holstein cows in midlactation (600±21 kg body weight) with permanent ruminal cannulas were selected as experimental animals, and the rumen degradation rates of dry matter (DM),organic matter (OM),crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of four rations were measured using nylon bag method. The culture time of rations in the rumen was 2, 4, 8, 16, 24, 36, 48 and 72 h, respectively. The results showed that differences were found in common nutritional components, and rumen effective degradability of DM, OM, CP, NDF and ADF among four different neutral detergent fiber/starch ratio diets. Ranking of the rumen effective degradability of DM, OM, CP, NDF and ADF among four diets from high to low was group Ⅰ>Ⅱ>Ⅲ>Ⅳ, Ⅰ>Ⅱ>Ⅲ>Ⅳ, Ⅱ>Ⅰ>Ⅳ>Ⅲ, Ⅰ>Ⅱ>Ⅳ>Ⅲ, Ⅰ>Ⅳ>Ⅲ>Ⅱ, respectively. In conclusion, in order to provide a basic parameters and theoretical foundation in formulating rations of dairy cows and use feed resources more effectively, ruminal degradation characteristics of rations are dissimilar, dietary ratio of NDF/Starch between 0.86 and 1.13, have the higher nutritive value among the four types of testing rations.