effect of prepartum dietary carbohydrate source on feed intake, energy balance, rumen fermentation, and milk yield and components of holstein cows

sixty eight holstein cows, 38 primiparous and 30 multiparous ones, were employed in a randomized complete block design, blocked to evaluate the effects of 2 diets in various ruminal fermentable carbohydrate sources (ground corn vs rolled wheat) on rumen fermentation and performance during preparturient period. primiparous and multiparous cows were blocked by parity. the cows were fed diets as total mixed ration with similar energy and crude protein content including 1) 18.57% gc; 2) 18.57% rw from -23.1 ± 9 d relative to expected calving until calving. followeing calving, all the animals received the same lactation diet for 28 days. the results revealed that, dry matter intake, energy intake, energy balance, and body condition score did not differ between multiparous cows fed either the ground corn or rolled wheat diet at preparturient period. dry matter intake, energy intake, and energy balance were lower for primiparous cows fed the rolled wheat diet at prepartum period (p