The effect of starch sources with different degradability rates on milk production and composition in lactating cows

The purpose of this study was to investigate the effect of starch sources with different degradability rates on chewing activities, milk production and composition of lactating dairy cows. Twelve lactating Holstein cows were used in a 4 x 4 Latin square design and fed with diets containing different rates of corn and wheat. The diets were: 1) 26.20% corn based diet (CBD), 2) 16.10% corn and 7.09% wheat based diet (CWBD), 3) 16.51% wheat and 7.26% corn based diet (WCBD), or 4) 25.88% wheat based diet (WBD). The eating, ruminating and total chewing time were not affected by the treatments and time spent total chewing time ranged from 761 to 801 min/d. Cows fed with CBD higher milk production, fat, protein and lactose yield than did cows fed with WCBD and WBD (P