The objective of this study was to evaluate the effects of dietary starch level on performance, feed intake, nutrient digestability, nitrogen efficiency, feeding behavior and income over feed cost of Holstein dairy cow in early lactation. Nine multiparous early lactating Holstein cow with 65.6 ± 8.5 DIM, average milk yield of 55.6 ± 4.5, and the average body weight of 611.3 ± 43.3 kg (mean ± SD) were used in a 3 × 3 latin square design with 21 d periods. Each period consisted of 16 d of adaptation followed by 5 d of data collection. Different dietary starch were made by replacing corn grain by corn germ. Treatment diets were: control, alternative diet (replacing corn grain with corn germ completly), and balanced treatment, (replacing corn grain with corn germ and balanced).The control, alternate and balanced diets contained 30.2, 24.3 and 24.8 % starch (DM % basis), respectively. Control and balanced diets were isoenergetic (1.6 Mcal / kgDM). Decreased dietary starch by replacing corn grain with corn germ had no effect on the proportion of the particles retained on the two top sieves of the ( 19 mm and 8 mm), but proportion of the particles retained on the 1.18 mm sieve and pen were affected by treatments ( P 0.01), so peNDF 1.18 increased by replacing corn grain by corn germ ( P 0.01). Reducing dietary starch had a significant effect on milk yield, 3.5 % FCM, ECM, production of protein, and lactose. The highest milk yield observed in the alternative diet with 56.6 (kg / day) and the lowest in control with 53.7 (kg / day), while percentage of fat, protein, lactose and SNF were unaffected by treatments. Decreasing dietary starch, had no effect on dry matter intake ( P 0.1), and as a result, feed efficiency (MY / DMI, 3.5 % FCM / DMI) was unaffective too. Total-tract digestability of DM and OM had a tendency to redused by decreasing starch content of diets. Rumen pH unaffected by treatments while feces pH had a tendency to increase by reducing starch content of diets. Body weight unaffected by treatments,while body condition score and back fat thickness were affected by treatments ( P 0.05). Plasma BHBA, NEFA and glucose were not affected by treatments but plasma cholesterol increased with redusing dietary starch (p = 0.04). Price of diet with reduced starch content of diet decreased (rials / kgDM), so the highest income observed in alternative diet. The results suggest that reduced dietary starch from 30.2 % to 24.8% by replacing corn grain with corn germ, in high concentrate diets can successfully support performance of high producing Holstein cows in early-lactation Keywords : Corn germ, Diet starch, Dairy cow, Performance
