The Study the Effects of Different Levels of Physical Effective Neutral Detergent 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 kg in 23 d before expected calving date were assigned in a completely randomized design (n = 6) to study the effects of different levels of effective neutral detergent fiber (peNDF) on feed intake and nutrients digestibility in close-up and performance in the subsequent lactation. The effective neutral detergent fiber was considered as high 30. 40 (H)، moderate 27. 38 (M) and low 24. 61% (L). These changes were induced by alfalfa، corn silage and barely grain alterations in diets. All the cows were fed the same diet after parturition. Total rumination time was 473، 443 and 408 min/d for treatments H، M and L، respectively (P < 0. 03). Pre-calving DMI was 12. 07، 14. 29 and 12. 89 kg/d، (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 peNDF. Total chewing activity negatively affected by decreasing the peNDF content in the diet. The results of the present study indicated that decreasing the peNDF in close-up diets have potential to increased DMI in both pre and post calving. We conclude that although the strategy of decreasing peNDF content of the close-up diets increases DMI and had potential to improve energy balance in dairy cows; the severe decrease of peNDF in close-up diets could negatively affect rumination time that possibly could have negative effects on cow health.