The objective of this study was to determine the effects of feeding starter diets containing either chopped wheat straw (WS), chopped alfalfa hay (ALF) or their mixture (WA), and forage free starter diet (CO) on feed and water intakes, growth rate, blood metabolites, feeding behavior, ruminal pH, and structural body characteristics of Holstein calves. Sixty newborn Holstein calves (30 males and 30 females) were blocked based on sex and randomly assigned to one of four dietary treatments. The treatments included feeding dry starter diets with 1) no forage (CO), 2) chopped wheat straw (WS), 3) chopped alfalfa hay (ALF), or 4) a 50:50 mixture of wheat straw and alfalfa hay (WA). The dietary inclusion rate of forage was 5% from d 3 to 21 and 10% from d 22 until weaning and 2 weeks post-weaning. The starter diets were offered as totally mixed rations. Feed intake of individual calves was measured daily and body weight (BW) was monitored biweekly. Jugular blood samples were taken to measure serum metabolites on d 21 and 63. The calves in the WS group had greater (P<0.05) starter DM (1327 vs. 902 (g/d]), and neutral detergent fiber (NDF) (233 vs. 98 (g/d]) intakes than calves in the CO group. Calves fed forage had greater acid-detergent fiber (ADF) intake than calves fed CO diet (P<0.01). The total starter intake preweaning (100 vs. 76 and 73 (kg]) and dry matter intake (DMI) post-weaning (63 vs. 43 and 42 (kg]) were greater (P<0.05) for WS compared with ALF and CO calves, respectively. The average daily gain (average daily gain (ADG), 727 vs. 633 (g/d]) and average BW (65 vs. 60 (kg]) tended to be greater for WS relative to others (P<0.10). The average final body weight (BW) (97.7 vs. 85.3 (kg]) and total post-weaning weight gain (13.4 vs. 9.5 (kg]) were greater in WS compared with ALF (P<0.05), but was similar among WS, CO and WA groups. Ruminal pH tended to be greater (P=0.09) for WS (6.28) and WA (6.36) than for CO (5.61) and ALF (5.88). There was a tendency to decrease in non-nutritive oral behaviors for WS (21 min/d) compared with CO (59 (min/d]). Overall, find-ings suggest that forage in calf starter diets (mashed) could improve DMI and growth, with chopped WS being more effective than ALF under the conditions of this study. To imply, the indigestible and physically effective fiber of WS was able to stabilize rumen conditions and successfully stimulate greater starter in-take. پرونده مقاله