Effects of Different Levels of Effective Fiber in Close-up Cows Diets on Intake and Chewing Activity and Subsequent Lactation Performance in Holstein Dairy Cows

The 18 multiparous close-up Holstein dairy cows averaging BW 791.1 (SD = 44.72) in 23 day (SD = 6) before expected calving date were assigned in a completely randomized design (n = 6) to study the effects of different levels of effective fiber on chewing activity, intake and nutrients digestibility in close-up and performance in the subsequent lactation. The effective fiber was considered as high 30.40, moderate 27.38 and low 24.61% for treatments H, M and L, respectively. All the cows were fed the same diet after parturition until 20 days in milk. Total chewing activity negatively affected by decreasing the effective fiber content in the diet. Total rumination time was 473, 443 and 408 min day(-1) for treatments H, M and L, respectively (p<0.03). Pre-calving DMI was 12.07, 14.29 and 12.89 kg day(-1), (p<0.0007) and post-calving DMI was 17.41, 19.03 and 18.72 for treatments H, M and L, respectively (p<0.0001). Milk yield (p<0.09) and milk protein yield (p<0.07) were tended to rise with decreasing the effective fiber but there was no effect on milk fat yield among treatments. The results showed that decreasing the effective fiber in close-up diets increased DMI in both pre and post calving. It was concluded that although the strategy of decreasing effective fiber content of the close-up diets increases DMI and improved energy balance in dairy cows, the severe decrease of effective fiber in close-up diets could negatively affect rumination time that possibly could have negative effects on cow health.